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Sample records for double electron capture

  1. Double electron capture searches in 74Se

    NASA Astrophysics Data System (ADS)

    Lehnert, B.; Wester, T.; Degering, D.; Sommer, D.; Wagner, L.; Zuber, K.

    2016-08-01

    A search for various double electron capture modes of 74Se has been performed using an ultralow background Ge-detector in the Felsenkeller laboratory, Germany. Especially for the potentially resonant transition into the 1204.2 keV excited state of 74Ge a lower half-life limit of 0.70× {10}19 yr (90% credibility) has been obtained. Serious concerns are raised about the validity of obtained 74Se limits in some recent publications.

  2. Search for neutrinoless double-electron capture of 156Dy

    NASA Astrophysics Data System (ADS)

    Finch, S. W.; Tornow, W.

    2015-12-01

    Background: Multiple large collaborations are currently searching for neutrinoless double-β decay, with the ultimate goal of differentiating the Majorana-Dirac nature of the neutrino. Purpose: Investigate the feasibility of resonant neutrinoless double-electron capture, an experimental alternative to neutrinoless double-β decay. Method: Two clover germanium detectors were operated underground in coincidence to search for the de-excitation γ rays of 156Gd following the neutrinoless double-electron capture of 156Dy. 231.95 d of data were collected at the Kimballton underground research facility with a 231.57 mg enriched 156Dy sample. Results: No counts were seen above background and half-life limits are set at O (1016-1018) yr for the various decay modes of 156Dy. Conclusion: Low background spectra were efficiently collected in the search for neutrinoless double-electron capture of 156Dy, although the low natural abundance and associated lack of large quantities of enriched samples hinders the experimental reach.

  3. Multiple-resonance phenomenon in neutrinoless double-electron capture

    SciTech Connect

    Eliseev, S.; Goncharov, M.; Blaum, K.; Block, M.; Herfurth, F.; Minaya Ramirez, E.; Droese, C.; Schweikhard, L.; Novikov, Yu. N.; Shabaev, V. M.; Tupitsyn, I. I.; Zubova, N. A.; Zuber, K.

    2011-07-15

    A superposition of multiple resonance states in neutrinoless double-electron capture in {sup 156}Dy has been discovered. Penning-trap mass spectrometry has been used for atomic-mass-difference measurements and careful calculations of electron wave functions and double-hole binding energies have been performed to determine the resonance-enhancement factors. Transitions to four nuclear excited states in the daughter nuclide {sup 156}Gd have been identified as resonantly enhanced, including one with a full resonant enhancement, within the uncertainty of 100 eV. This phenomenon is unique in that it can be used to probe the mechanisms of neutrinoless processes.

  4. Search for double electron capture of 106Cd

    NASA Astrophysics Data System (ADS)

    Rukhadze, N. I.; Beneš, P.; Briançon, Ch.; Brudanin, V. B.; Čermák, P.; Danevich, F. A.; Egorov, V. G.; Gusev, K. N.; Klimenko, A. A.; Kovalenko, V. E.; Kovalik, A.; Salamatin, A. V.; Štekl, I.; Timkin, V. V.; Tretyak, V. I.; Vylov, Ts.

    2006-12-01

    A search for double electron capture of 106Cd was performed at the Modane Underground Laboratory (4800 m w.e.) using a low-background and high-sensitivity multidetector spectrometer TGV-2 (Telescope Germanium Vertical). New limits on β +/EC, EC/EC decays of 106Cd were obtained from preliminary calculations of experimental data accumulated for 4800 h of measurement of 10 g of 106Cd with enrichment of 75%. They are > 6.2 × 1019 yr for transitions to the ground 0+ state of 106Pd. All limits are given at 90% C.L.

  5. Use of silicon pixel detectors in double electron capture experiments

    NASA Astrophysics Data System (ADS)

    Cermak, P.; Stekl, I.; Shitov, Yu A.; Mamedov, F.; Rukhadze, E. N.; Jose, J. M.; Cermak, J.; Rukhadze, N. I.; Brudanin, V. B.; Loaiza, P.

    2011-01-01

    A novel experimental approach to search for double electron capture (EC/EC) is discussed in this article. R&D for a new generation EC/EC spectrometer based on silicon pixel detectors (SPDs) has been conducted since 2009 for an upgrade of the TGV experiment. SPDs built on Timepix technology with a spectroscopic readout from each individual pixel are an effective tool to detect the 2νEC/EC signature of the two low energy X-rays hitting two separate pixels. The ability of SPDs to indentify α/β/γ particles and localize them precisely leads to effective background discrimination and thus considerable improvement of the signal-to-background ratio (S/B). A multi-SPD system, called a Silicon Pixel Telescope (SPT), is planned based on the experimental approach of the TGV calorimeter which measures thin foils of enriched EC/EC-isotope sandwiched between HPGe detectors working in coincidence mode. The sources of SPD internal background have been identified by measuring SPD radiopurity with a low-background HPGe detector as well as by long-term SPD background runs in the Modane underground laboratory (LSM, France), and results of these studies are presented.

  6. Double resonant enhancement in the neutrinoless double-electron capture of 190Pt

    NASA Astrophysics Data System (ADS)

    Eibach, M.; Bollen, G.; Gulyuz, K.; Izzo, C.; Redshaw, M.; Ringle, R.; Sandler, R.; Valverde, A. A.

    2016-07-01

    Background: The observation of neutrinoless double-β transitions would indicate physics beyond the standard model as the lepton number conservation is violated. For a complete degeneracy in the energy of the initial and final states, the neutrinoless double-electron capture is resonantly enhanced. This shortens the half-life to similar orders of magnitude as the neutrinoless double-β decay and expands the set of nuclei for the search of neutrinoless double-β transitions as the observation of either process would be equally likely. Purpose: To clearly identify transitions that are resonantly enhanced, among other parameters the total energy of the decay, Qɛ ɛ, needs to be measured very precisely. Of the 12 initially identified candidates, the last remaining decay without a precise Qɛ ɛ was 190Pt(0 ν ɛ ɛ )190Os . Method: The Qɛ ɛ value was determined with the Penning trap mass spectrometer LEBIT by measuring the ratio of the cyclotron frequencies of +190Pt and +190Os in a 9.4-T superconducting magnet. Result: The Qɛ ɛ value was determined to be 1401.57(47) keV with an uncertainty reduction of an order of magnitude compared to its previously known value. The absolute value is shifted by 17.17(623) keV relative to the previously accepted one. Furthermore, the mass value of 190Pt was found to be shifted by more than three standard deviations. In addition we improved the mass values for Os,190186 and 194Pt. Conclusion: Transitions to the two nuclear excited states of 190Os with 1326.9(5) and 1387.00(2) keV energy were identified to be resonantly enhanced within a 1 σ uncertainty. The significantly reduced uncertainty of Qɛ ɛ confirmed the potential for a resonantly enhanced transition.

  7. Radiative double electron capture (RDEC) by bare fluorine ions on a nitrogen target

    NASA Astrophysics Data System (ADS)

    Kumara, Nuwan; La Mantia, David; Kayani, Asghar; Simon, Anna; Tanis, John

    2016-05-01

    Unlike radiative electron capture (REC), in which a single photon is emitted due to capture of a single electron from the target to the projectile, radiative double electron capture (RDEC) involves two electrons accompanied by the emission of a single photon. Hence, RDEC can be considered as the inverse of double photoionization and used to study the role of electron correlation in causing the process. We report recent results obtained for 40 MeV F9+ ions incident on a nitrogen target, in which counts were observed in the calculated RDEC region (2.8-4.4 keV) for the system. Based on these observations an approximate value for the total RDEC cross section was estimated. Compared with the data obtained for 38 MeV O8+ ions incident on a carbon foil target, the present value is considerably smaller than the value found for carbon, but in better agreement with recent theory. Supported in part by NSF.

  8. Experiment TGV II: results on double electron capture in 106Cd

    NASA Astrophysics Data System (ADS)

    Cermak, P.; Benes, P.; Briançon, C.; Brudanin, V. B.; Egorov, V. G.; Gusev, K. N.; Klimenko, A. A.; Kovalenko, V. E.; Kovalik, A.; Rukhadze, N. I.; Salamatin, A. V.; Simkovic, F.; Stekl, I.; Timkin, V. V.; Vylov, T.

    2008-06-01

    The TGV II (Telescope Germanium Vertical) facility is a low background spectrometer operated in Modane Underground Laboratory. It aims at the study of double electron capture of 106Cd. The spectrometer is composed of 32 HPGe planar detectors interleaved with thin-foil samples made of 106Cd enriched to 75%. In 2006, the main run of phase I (1 year duration) was terminated yielding a new limit on half-life for two-neutrino double electron capture in 106Cd as 2.0x1020y. The new limit is significantly higher (by almost three orders of magnitude) than those already published.

  9. Influence of electron correlations on double-capture process in proton-helium collisions

    NASA Astrophysics Data System (ADS)

    Hoda, Ghavaminia; Ebrahim, Ghanbari-Adivi

    2015-07-01

    The first-order correct-boundary Coulomb-Born distorted-wave approximation is used to study the double-electron capture by protons from the ground-state helium atoms at intermediate and high impact energies. The differential double capture cross sections are obtained as a function of the projectile scattering angle and the total cross sections as a function of the impact energy. In the considered range of impact energy, our calculation shows that although the results are not so sensitive to the static inter-electronic correlations in the initial channel, the strong final-state correlations have a large effect on the magnitudes of the double capture cross sections. The calculated differential and integral cross sections are compared with their available experimental values. The comparison shows a good agreement between the present calculations and the measurements. The comparison of the integral cross sections shows that the present approach is compatible with other theories.

  10. Probing the nuclides {sup 102}Pd, {sup 106}Cd, and {sup 144}Sm for resonant neutrinoless double-electron capture

    SciTech Connect

    Goncharov, M.; Blaum, K.; Eliseev, S.; Block, M.; Herfurth, F.; Minaya Ramirez, E.; Droese, C.; Schweikhard, L.; Novikov, Yu. N.; Zuber, K.

    2011-08-15

    The Q values for double-electron capture in {sup 102}Pd, {sup 106}Cd, and {sup 144}Sm have been measured by Penning-trap mass spectrometry. The results exclude at present all three nuclides from the list of suitable candidates for a search for resonant neutrinoless double-electron capture.

  11. Radiative double electron capture in collisions of fully-stripped fluorine ions with thin carbon foils

    NASA Astrophysics Data System (ADS)

    Elkafrawy, Tamer Mohammad Samy

    Radiative double electron capture (RDEC) is a one-step process in ion-atom collisions occurring when two target electrons are captured to a bound state of the projectile simultaneously with the emission of a single photon. The emitted photon has approximately double the energy of the photon emitted due to radiative electron capture (REC), which occurs when a target electron is captured to a projectile bound state with simultaneous emission of a photon. REC and RDEC can be treated as time-reversed photoionization (PI) and double photoionization (DPI), respectively, if loosely-bound target electrons are captured. This concept can be formulated with the principle of detailed balance, in which the processes of our interest can be described in terms of their time-reversed ones. Fully-stripped ions were used as projectiles in the performed RDEC experiments, providing a recipient system free of electron-related Coulomb fields. This allows the target electrons to be transferred without interaction with any of the projectile electrons, enabling accurate investigation of the electron-electron interaction in the vicinity of electromagnetic field. In this dissertation, RDEC was investigated during the collision of fully-stripped fluorine ions with a thin carbon foil and the results are compared with the recent experimental and theoretical studies. In the current work, x rays associated with projectile charge-changing by single and double electron capture and no charge change by F9+ ions were observed and compared with recent work for O8+ ions and with theory. Both the F 9+ and O8+ ions had energies in the ˜MeV/u range. REC, in turn, was investigated as a means to compare with the theoretical predictions of the RDEC/REC cross section ratio. The most significant background processes including various mechanisms of x-ray emission that may interfere with the energy region of interest are addressed in detail. This enables isolation of the contributions of REC and RDEC from the

  12. A search for the radiative neutrinoless double-electron capture of 58Ni

    NASA Astrophysics Data System (ADS)

    Lehnert, B.; Degering, D.; Frotscher, A.; Michel, T.; Zuber, K.

    2016-06-01

    A search for the radiative neutrinoless double-electron capture with single γ-ray emission has been performed in 58Ni. Gamma radiation from a 7286 {{g}} nickel sample in natural isotope composition was measured for 58.3 {{d}} with an ultra-low background HPGe detector in the Felsenkeller underground laboratory in Dresden, Germany. A new lower half-life limit of 2.1× {10}21 yr (90% CL) was obtained for this decay mode. This half-life limit is two orders of magnitude higher than the existing limit for 58Ni and among the best half-life limits for neutrinoless double-electron capture decays.

  13. Search for double electron capture on 124Xe with the XMASS-I detector

    NASA Astrophysics Data System (ADS)

    Hiraide, Katsuki; XMASS Collaboration

    2016-05-01

    The XMASS project is a multi-purpose experiment using highly-purified liquid xenon scintillator located underground at the Kamioka Observatory in Japan. A search for two-neutrino double electron capture on 124Xe is performed using 165.9 days of data collected with the XMASS-I detector. No significant excess above background was observed and we set a lower limit on the half-life as 4.7 × 1021 years at 90% confidence level.

  14. Electron-correlation driven capture and release in double quantum dots.

    PubMed

    Pont, Federico M; Bande, Annika; Cederbaum, Lorenz S

    2016-02-24

    We recently predicted that the interatomic Coulombic electron capture (ICEC) process, a long-range electron correlation driven capture process, is achievable in gated double quantum dots (DQDs). In ICEC an incoming electron is captured by one quantum dot (QD) and the excess energy is used to remove an electron from the neighboring QD. In this work we present systematic full three-dimensional electron dynamics calculations in quasi-one dimensional model potentials that allow for a detailed understanding of the connection between the DQD geometry and the reaction probability for the ICEC process. We derive an effective one-dimensional approach and show that its results compare very well with those obtained using the full three-dimensional calculations. This approach substantially reduces the computation times. The investigation of the electronic structure for various DQD geometries for which the ICEC process can take place clarify the origin of its remarkably high probability in the presence of two-electron resonances. PMID:26809134

  15. Evidence of Double-Electron Capture by Highly-ionized Atoms Isolated at Very Low Energy

    NASA Astrophysics Data System (ADS)

    Fogwell Hoogerheide, Shannon; Sahiner, Arda; Tan, Joseph N.

    2015-05-01

    Electron capture processes are important in the study of comets, controlled fusion energy, anti-matter atoms, and proposed one-electron ions in Rydberg states. There are few studies for low energy. At NIST, highly-charged ions extracted from an electron-beam ion trap can be isolated with <10 eV energy using a recently developed compact Penning trap. By controlling the background gas pressure and composition, the charge exchange rates can be studied. Fully stripped neon ions are held in the trap for varying lengths of time and allowed to interact with different background gases at multiple pressures. The ions are then pulsed to a time-of-flight detector, to count the population of each charge state. Analysis yields information about the trap loss and single-electron capture rates. Moreover, evidence of double-electron capture is observed at low background gas pressures. Related work involves the resonant charge exchange of fully-stripped neon ions with laser-excited rubidium atoms to produce highly-excited one-electron ions, enabling a new measurement of the Rydberg constant. SFH funded by a National Research Council Research Associateship Award

  16. Double-Beta Decay of 96Zr and Double-Electron Capture of 156Dy to Excited Final States

    NASA Astrophysics Data System (ADS)

    Finch, Sean W.

    Two separate experimental searches for second-order weak nuclear decays to excited final states were conducted. Both experiments were carried out at the Kimballton Underground Research Facility to provide shielding from cosmic rays. The first search is for the two-neutrino double-beta decay of 96Zr to excited final states of the daughter nucleus, 96Mo. As a by product of this experiment, the beta decay of 96Zr was also investigated. Two coaxial high-purity germanium detectors were used in coincidence to detect gamma rays produced by the daughter nucleus as it de-excited to the ground state. After collecting 1.92 years of data with 17.91 g of enriched 96Zr, half-life limits at the level of 10 20 yr were produced. Measurements of this decay are important to test neutrinoless double-beta decay nuclear matrix element calculations, which are necessary to extract the neutrino mass from a measurement of the neutrinoless double-beta decay half-life. The second experiment is a search for the resonantly-enhanced neutrinoless double-electron capture decay of 156Dy to excited states in 156Gd. Double-electron capture is a possible experimental alternative to neutrinoless-double beta decay, which could distinguish the Dirac or Majorana nature of the neutrino. Two clover high-purity germanium detectors were used in coincidence to investigate the decay. A 213.5 mg enriched 156Dy sample was observed for 0.635 year, producing half-life limits of 10 17 yr. The limits produced by both of these experiments are currently the most stringent limits available for these decays.

  17. Double-electron capture by highly-ionized atoms isolated at very low energy

    NASA Astrophysics Data System (ADS)

    Fogwell Hoogerheide, Shannon; Dreiling, Joan M.; Sahiner, Arda; Tan, Joseph N.

    2016-05-01

    Charge exchange with background gases, also known as electron capture processes, is important in the study of comets, controlled fusion energy, anti-matter atoms, and proposed one-electron ions in Rydberg states. However, there are few experiments in the very low energy regime that could be useful for further theoretical development. At NIST, highly-charged ions extracted from an electron-beam ion trap can be isolated with energy < 10 eV in a compact Penning trap. By controlling the background gas pressure and composition, the charge exchange rates can be studied. Fully stripped neon or other ions are held in the trap for varying lengths of time and allowed to interact with different background gases at multiple pressures. The ions are then pulsed to a time-of-flight detector to count the population of each charge state. Analysis using a system of rate equations yields information about the ion cloud expansion and single-electron capture rates. A substantial amount of double-electron capture is also observed. We present the relative rates and discuss the error budget. SFH and JMD were funded by National Research Council Research Associateship Awards during some of this work.

  18. Studies of electron correlation effects in multicharged ion atom collisions involving double capture

    SciTech Connect

    Stolterfoht, N.; Sommer, K.; Griffin, D.C.; Havener, C.C.; Huq, M.S.; Phaneuf, R.A.; Swenson, J.K.; Meyer, F.W.

    1988-01-01

    We review measurements of L-Coster Kronig and Auger electron production in slow, multicharged collision systems to study electron correlation effects in the process of double electron capture. The n/sup /minus/3/ law was confirmed for the production of the Coster-Kronig configurations 1s/sup 2/2pn/ell/ (n greater than or equal to 6) in O/sup 6 +/ + He collisions. Enhancement of high angular momentum /ell/ in specific 1s/sup 2/2pn/ell/ configurations was observed by means of high-resolution measurements of the Coster-Kronig lines. The importance of electron correlation effects in couplings of potential energy curves leading to the 1s/sup 2/2pn/ell/ configurations is verified by means of Landau-Zener model calculations. 32 refs., 4 figs.

  19. Accurate Q-Value for the ^{74}Se Double Electron Capture Decay

    SciTech Connect

    Kolhinen, V. S.; Elomaa, V.-V.; Eronen, T.; Hakala, J.; Jokinen, A.; Kortelainen, M.; Suhonen, J.; Aysto, J.

    2010-01-01

    The Q value of the neutrinoless double electron capture (0{nu}ECEC) decay of ^{74}Se was measured by using the JYFLTRAP Penning trap. The determined value is 1209.169(49) keV, which practically excludes the possibility of a complete energy degeneracy with the second 2^{+} state (1204-205(7) keV) of ^{74}Ge in a resoant 0{nu}ECEC decay. We have also computed the associated nuclear matrix element by using a microscopic nuclear model with realistic two-nucleon interactions. The computed matrix element is found to be quite small. The failure of the resonant condition, combined with the small nuclear matrix element and needed p-wave capture, suppresses the decay rate strongly and thus excludes ^{74}Se as a possible candidate to search for resonant 0{nu}ECEC processes.

  20. Search for two-neutrino double electron capture on 124Xe with the XMASS-I detector

    NASA Astrophysics Data System (ADS)

    Abe, K.; Hiraide, K.; Ichimura, K.; Kishimoto, Y.; Kobayashi, K.; Kobayashi, M.; Moriyama, S.; Nakagawa, K.; Nakahata, M.; Norita, T.; Ogawa, H.; Sekiya, H.; Takachio, O.; Takeda, A.; Yamashita, M.; Yang, B. S.; Kim, N. Y.; Kim, Y. D.; Tasaka, S.; Liu, J.; Martens, K.; Suzuki, Y.; Fujita, R.; Hosokawa, K.; Miuchi, K.; Oka, N.; Onishi, Y.; Takeuchi, Y.; Kim, Y. H.; Lee, J. S.; Lee, K. B.; Lee, M. K.; Fukuda, Y.; Itow, Y.; Kegasa, R.; Kobayashi, K.; Masuda, K.; Takiya, H.; Uchida, H.; Nishijima, K.; Fujii, K.; Murayama, I.; Nakamura, S.

    2016-08-01

    Double electron capture is a rare nuclear decay process in which two orbital electrons are captured simultaneously in the same nucleus. Measurement of its two-neutrino mode would provide a new reference for the calculation of nuclear matrix elements whereas observation of its neutrinoless mode would demonstrate lepton number violation. A search for two-neutrino double electron capture on 124Xe is performed using 165.9 days of data collected with the XMASS-I liquid xenon detector. No significant excess above background was observed and we set a lower limit on the half-life as 4.7 ×1021 years at 90% confidence level. The obtained limit has ruled out parts of some theoretical expectations. We obtain a lower limit on the 126Xe two-neutrino double electron capture half-life of 4.3 ×1021 years at 90% confidence level as well.

  1. Q value and half-life of double-electron capture in 184Os

    NASA Astrophysics Data System (ADS)

    Smorra, C.; Rodríguez, T. R.; Beyer, T.; Blaum, K.; Block, M.; Düllmann, Ch. E.; Eberhardt, K.; Eibach, M.; Eliseev, S.; Langanke, K.; Martínez-Pinedo, G.; Nagy, Sz.; Nörtershäuser, W.; Renisch, D.; Shabaev, V. M.; Tupitsyn, I. I.; Zubova, N. A.

    2012-10-01

    184Os has been excluded as a promising candidate for the search of neutrinoless double-electron capture. High-precision mass measurements with the Penning-trap mass spectrometer TRIGA-TRAP result in a marginal resonant enhancement with Δ=-8.89(58) keV excess energy to the 1322.152(22) keV 0+ excited state in 184W. State-of-the-art energy density functional calculations are applied for the evaluation of the nuclear matrix elements to the excited states predicting a strong suppression due to the large deformation of mother and daughter states. The half-life of the transition exceeds T1/2(184Os)≥1.3×1029 yr for an effective neutrino mass of 1 eV.

  2. Examination of the possible enhancement of neutrinoless double-electron capture in 78Kr

    NASA Astrophysics Data System (ADS)

    Bustabad, S.; Bollen, G.; Brodeur, M.; Lincoln, D. L.; Novario, S. J.; Redshaw, M.; Ringle, R.; Schwarz, S.

    2013-09-01

    Penning-trap mass spectrometry was used at the Low-Energy Beam and Ion Trap (LEBIT) facility at the National Superconducting Cyclotron Laboratory (NSCL) to investigate 78Kr, a candidate for resonantly enhanced neutrinoless double-electron capture (0νECEC). The newly determined Q value of 2847.75 (27) keV is 1.4 keV greater than the value from the most recent atomic mass evaluation [Chin. Phys. C1674-113710.1088/1674-1137/36/12/003 36, 1603 (2012)], a change of two sigma, and the uncertainty has been reduced by a factor of three. The change in the Q value shifts allowed 0νECEC in 78Kr further from resonant enhancement. With the improved determination of the Q value, all known excited states can now be confidently excluded from possible 78Se candidates that could lead to resonantly enhanced 0νECEC.

  3. Double electron capture of 106Cd in the TGV-2 experiment

    NASA Astrophysics Data System (ADS)

    Rukhadze, N. I.; Briancon, Ch.; Brudanin, V. B.; Egorov, V. G.; Fajt, L.; Hodák, R.; Klimenko, A. A.; Kovalik, A.; Kouba, P.; Piquemal, F.; Rozov, S. V.; Rukhadze, E.; Rychnovský, F.; Salamatin, A. V.; Šimkovic, F.; Shitov, Yu. A.; Štekl, I.; Timkin, V. V.; Yakushev, E. A.

    2015-10-01

    A new experimental run of searching for EC/EC decay of 106Cd was performed at the Modane underground laboratory (4800 m w.e.) using the TGV-2 spectrometer and ˜23.2 g 106Cd with enrichment of 99.57%. The limit on 2νEC/EC decay of 106Cd - T1/2(2νEC/EC) > 3.1×1020 y, at 90% C.L was obtained from the preliminary calculation of experimental data accumulated for 7018 h of measurement. The limits on the resonance neutrino-less double electron capture decay of 106Cd were obtained from the measurement of ˜23.2 g of 106Cd with the low-background HPGe spectrometer OBELIX lasted 395 h - T1/2(KL, 2741 keV) > 0.9×1020 y and T1/2(KK, 2718 keV) > 1.4×1020 y at 90% C.L.

  4. New search for double electron capture in 106Cd decay with the TGV-2 spectrometer

    NASA Astrophysics Data System (ADS)

    Briançon, Ch.; Brudanin, V. B.; Egorov, V. G.; Jose, J. M.; Klimenko, A. A.; Kovalik, A.; Rosov, S. V.; Rukhadze, E. N.; Rukhadze, N. I.; Salamatin, A. V.; Timkin, V. V.; Fajt, L.; Hodak, R.; Šimkovic, F.; Shitov, Yu. A.; Špavorova, M.; Štekl, I.; Yakushev, E. A.

    2015-09-01

    A new experiment devoted to searches for double electron capture in 106Cd decay is being performed at the Modane underground laboratory (4800 mwe) with the 32-detector TGV-2 spectrometer. The limit T 1/2(2 νEC/EC) > 2.0×1020 yr at a 90%confidence level (C.L.) was obtained from a preliminary analysis of data obtained over 2250 h of measurements with about 23.2 g sample enriched in the isotope 106Cd to 99.57%. The limits T 1/2(KL, 2741 keV) > 0.9 × 1020 yr and T 1/2(KK, 2718 keV) ≫ 1.4 × 1020 yr at a 90% C.L. on the neutrinoless decay of 106Cd were obtained from measurements performed with the Obelix low-background spectrometer from high-purity germanium (HPGe spectrometer) for a sample of mass about 23.2 g enriched in the isotope 106Cd.

  5. Double electron capture of {sup 106}Cd in the TGV-2 experiment

    SciTech Connect

    Rukhadze, N. I.; Egorov, V. G.; Kovalik, A.; Rozov, S. V.; Salamatin, A. V.; Timkin, V. V.; Yakushev, E. A.; Briancon, Ch.; Brudanin, V. B.; Fajt, L.; Hodák, R.; Kouba, P.; Rukhadze, E.; Rychnovský, F.; Štekl, I.; Klimenko, A. A.; Piquemal, F.; Šimkovic, F.; Shitov, Yu. A.

    2015-10-28

    A new experimental run of searching for EC/EC decay of {sup 106}Cd was performed at the Modane underground laboratory (4800 m w.e.) using the TGV-2 spectrometer and ∼23.2 g {sup 106}Cd with enrichment of 99.57%. The limit on 2νEC/EC decay of {sup 106}Cd - T{sub 1/2}(2νEC/EC) > 3.1×10{sup 20} y, at 90% C.L was obtained from the preliminary calculation of experimental data accumulated for 7018 h of measurement. The limits on the resonance neutrino-less double electron capture decay of {sup 106}Cd were obtained from the measurement of ∼23.2 g of {sup 106}Cd with the low-background HPGe spectrometer OBELIX lasted 395 h - T{sub 1/2}(KL, 2741 keV) > 0.9×10{sup 20} y and T{sub 1/2}(KK, 2718 keV) > 1.4×10{sup 20} y at 90% C.L.

  6. New search for double electron capture in {sup 106}Cd decay with the TGV-2 spectrometer

    SciTech Connect

    Briançon, Ch.; Brudanin, V. B.; Egorov, V. G.; Jose, J. M.; Klimenko, A. A.; Kovalik, A.; Rosov, S. V.; Rukhadze, E. N.; Rukhadze, N. I. Salamatin, A. V.; Timkin, V. V.; Fajt, L.; Hodak, R.; Šimkovic, F.; Shitov, Yu. A.; Špavorova, M.; Štekl, I.; Yakushev, E. A.

    2015-09-15

    A new experiment devoted to searches for double electron capture in {sup 106}Cd decay is being performed at the Modane underground laboratory (4800 mwe) with the 32-detector TGV-2 spectrometer. The limit T{sub 1/2}(2νEC/EC) > 2.0×10{sup 20} yr at a 90%confidence level (C.L.) was obtained from a preliminary analysis of data obtained over 2250 h of measurements with about 23.2 g sample enriched in the isotope {sup 106}Cd to 99.57%. The limits T{sub 1/2}(KL, 2741 keV) > 0.9 × 10{sup 20} yr and T{sub 1/2}(KK, 2718 keV) ≫ 1.4 × 10{sup 20} yr at a 90% C.L. on the neutrinoless decay of {sup 106}Cd were obtained from measurements performed with the Obelix low-background spectrometer from high-purity germanium (HPGe spectrometer) for a sample of mass about 23.2 g enriched in the isotope {sup 106}Cd.

  7. Degeneracy at 1871 keV in {sup 112}Cd and implications for neutrinoless double electron capture

    SciTech Connect

    Green, K. L.; Garrett, P. E.; Demand, G. A.; Grinyer, G. F.; Leach, K. G.; Phillips, A. A.; Schumaker, M. A.; Svensson, C. E.; Wong, J.; Austin, R. A. E.; Colosimo, S.; Ball, G. C.; Bandyopadhyay, D. S.; Hackman, G.; Morton, A. C.; Pearson, C. J.; Cross, D.; Kulp, W. D.; Wood, J. L.; Yates, S. W.

    2009-09-15

    High-statistics {beta}-decay measurements of {sup 112}Ag and {sup 112}In were performed to study the structure of the {sup 112}Cd nucleus. The precise energies of the doublet of levels at 1871 keV, for which the 0{sup +} member has been suggested as a possible daughter state following neutrinoless double electron capture of {sup 112}Sn, were determined to be 1871.137(72) keV (0{sub 4}{sup +} level) and 1870.743(54) keV (4{sub 2}{sup +} level). The nature of the 0{sub 4}{sup +} level, required for the calculation of the nuclear matrix element that would be needed to extract a neutrino mass from neutrinoless double electron capture to this state, is suggested to be of intruder origin.

  8. Electron-capture branch of {sup 100}Tc and tests of nuclear wave functions for double-{beta} decays.

    SciTech Connect

    Sjue, S. K. L.; Melconian, D.; Garcia, A.; Ahmad, I.; Algora, A.; Aysto, J.; Elomaa, V.-V.; Eronen, T.; Hakala, J.; Hoedl, S.; Kankainen, A.; Kessler, T.; Moore, I. D.; Naabe, F.; Penttila, H.; Rahaman, S.; Saastamoinen, A.; Swanson, H. E.; Weber, C.; Triambak, S.; Deryckx, K.; Physics; Univ. of Washington; Texas A&M Univ.; Univ. of Valencia; Hungarian Academy of Sciences; Univ. of Jyvaskyla; Univ. of Michigan

    2008-12-30

    We present a measurement of the electron-capture branch of {sup 100}Tc. Our value, B(EC) = (2.6 {+-} 0.4) x 10{sup -5}, implies that the {sup 100}Mo neutrino absorption cross section to the ground state of {sup 100}Tc is roughly 50% larger than previously thought. Disagreement between the experimental value and QRPA calculations relevant to double-{beta} decay matrix elements persists. We find agreement with previous measurements of the 539.5- and 590.8-keV {gamma}-ray intensities.

  9. State-selective differential cross sections for double-electron capture in 0.25{endash}0.75-MeV He{sup 2+}-He collisions

    SciTech Connect

    Doerner, R.; Mergel, V.; Spielberger, L.; Jagutzki, O.; Schmidt-Boecking, H.; Ullrich, J.

    1998-01-01

    For 0.25{endash}0.75-MeV He{sup 2+} on He collisions we have measured total state selective double capture cross sections and cross sections differential in projectile scattering angle. For 0.25 MeV we present also state-selective scattering-angle-dependent double-capture cross sections. The projectile energy loss (the final electronic state) as well as the transverse momentum transfer (i.e., the projectile scattering angle) have been obtained by measuring the momentum vector of the recoil ion using cold target recoil ion momenum spectroscopy. The resonant transfer to the ground state is found to be by far the dominant double-capture channel. Capture to nonautoionizing excited states is smaller by about a factor of 7, and results in larger scattering angles than the ground-state double capture. {copyright} {ital 1998} {ital The American Physical Society}

  10. A search for double-electron capture of 74Se to excited levels using coincidence/anticoincidence gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Ješkovský, M.; Frekers, D.; Kováčik, A.; Povinec, P. P.; Puppe, P.; Staníček, J.; Sýkora, I.; Šimkovic, F.; Thies, J. H.

    2015-09-01

    Evaluation of single, coincidence and anticoincidence gamma-ray spectrometry methods has been carried out with the aim to search for double-electron capture of 74Se to excited states. This process is unique, because there is probability for transition to the 2+ excited state in 74Ge (1204 keV), and de-excitation through two gamma-quanta cascade with energies of 595.9 keV and 608.4 keV. Long-term measurements with an anticosmic shielded HPGe (high purity Ge) spectrometer and a coincidence HPGe-NaI(Tl) spectrometer did not show any evidence for the double-electron capture in 74Se. The best limit for the half-life of the double electron capture in 74Se (both for the neutrinoless and two neutrino processes) was estimated to be >1.5×1019 yr.

  11. Single- and double-electron-capture collision of C{sup q+} (q=3,4) with CO at keV energies

    SciTech Connect

    Gao Hui; Kwong, Victor H.S.

    2004-05-01

    Absolute total single- and double-electron-capture cross sections for C{sup q+} (q=3,4) with CO have been measured at {approx}0.5 keV/amu using a reflection-time-of-flight mass spectrometer with a laser ablation ion source. The single- and double-electron-capture cross sections for C{sup 3+} with CO at 423{+-}48 eV/amu are found to be (0.96{+-}0.12)x10{sup -15} cm{sup 2} and (0.99{+-}0.13)x10{sup -15} cm{sup 2}, respectively. The single- and double-electron-capture cross sections for C{sup 4+} with CO at 565{+-}65 eV/amu are measured to be (3.16{+-}0.42)x10{sup -15} cm{sup 2} and (1.05{+-}0.21)x10{sup -15} cm{sup 2}, respectively. This suggests that double capture should not be ignored in modeling the emission from cascading processes in comet atmosphere.

  12. Single and double electron capture from He by Ar{sup 16+} studied using cold-target recoil-ion momentum spectroscopy

    SciTech Connect

    Abdallah, M.A.; Wolff, W.; Wolf, H.E.; Kamber, E.Y.; Stoeckli, M.; Cocke, C.L.

    1998-10-01

    Single and double electron capture from He targets by Ar{sup 16+} ions have been studied at projectile velocities from 0.3 to 1.5 a.u. Cold-target recoil-ion momentum spectroscopy was used to record the energy gain and scattering angle simultaneously. For single capture, the reaction window is found to spread in width approximately as the square root of the projectile velocity and to shift slightly toward smaller energy-gain values as the velocity increases. The angular distributions center at the half Coulomb angle over most of the velocity range covered, but differ in shape from multichannel Landau-Zener model results. For double capture, transfer ionization dominates and feeds primarily n-symmetric states, where {ital n} is the principal quantum number. True double capture feeds mainly n-asymmetric states. The angular distributions for double capture lie outside the half Coulomb angle, indicating the importance of two-step processes in populating doubly excited states. {copyright} {ital 1998} {ital The American Physical Society}

  13. Atomic electron correlation in nuclear electron capture

    NASA Technical Reports Server (NTRS)

    Chen, M. H.; Crasemann, B.

    1978-01-01

    The effect of electron-electron Coulomb correlation on orbital electron capture by the nucleus was treated by the multiconfigurational Hartree-Fock approach. The theoretical Be-7 L/K capture ratio was found to be 0.086, and the Ar-37 M/L ratio, 0.102. Both ratios were smaller than the independent particle predictions. Measurements exist for the Ar M/L ratio, and agreement between theory and experiment was excellent.

  14. Material capture by double lunar gravity assist

    NASA Technical Reports Server (NTRS)

    Ross, D. J.

    1980-01-01

    The equations yielding the performance of a single lunar flyby in removing incoming hyperbolic excess velocity to capture payloads on interplanetary trajectories are briefly derived. The impossibility of using a single lunar flyby to capture a body entering the earth-moon system with a hyperbolic velocity in excess of about 1.9 km/s is discussed, and a method of using a double flyby of the moon to significantly improve this performance is developed. The equations for achieving a double lunar flyby are derived by solving the orbital equations and Lambert's problem both for the incoming trajectory in the plane of the moon's orbit and for arbitrary declination. For the in-plane case it is shown that the maximum removable hyperbolic excess velocity is 2.2687 km/s. For the inclined case, it is shown that the use of a double lunar flyby allows capture for declinations in excess of 54 degrees, and that for declinations less than 38 degrees the double lunar flyby offers better performance than the single lunar flyby.

  15. First results for the measurement of double-electron capture of 106Cd in the experiment TGV II

    NASA Astrophysics Data System (ADS)

    Štekl, I.; Čermák, P.; Beneš, P.; Brudanin, V. B.; Gusev, K. N.; Egorov, V. G.; Klimenko, A. A.; Kovalenko, V. E.; Kovalík, A.; Rukhadze, N. I.; Salamatin, A. V.; Timkin, V. V.; Vylov, Ts.; Briançon, Ch.; Šimkovic, F.

    2006-05-01

    Present status of the experiment TGV II which is devoted to the measurement of double-beta decay of 106Cd is given. The low background spectrometer TGV II is installed in the Modane Underground Laboratory and has been running from February 2005 with approx 10 grams of 106Cd enriched at 75%. After an analysis of 3736 hours of experimental data the new improved half-life limit for 2νEC/EC decay of 106Cd (0 g.s. + → 0 g.s. + ) is given as T 1 2/2ν > 4.8 × 1019 years (90% CL). The search for 2νEC/EC decay of 106Cd to the excited states of 106Pd allows to determine the limits of the half-lives T 1 2/2ν (0 g.s. + → 2 1 + ) > 3.9 × 1019 years (90% CL) and T 1 2/2ν (0 g.s. + → 0 1 + ) > 5.8 × 1019 years (90% CL).

  16. Orbital electron capture by the nucleus

    NASA Technical Reports Server (NTRS)

    Bambynek, W.; Behrens, H.; Chen, M. H.; Crasemann, B.; Fitzpatrick, M. L.; Ledingham, K. W. D.; Genz, H.; Mutterer, M.; Intemann, R. L.

    1976-01-01

    The theory of nuclear electron capture is reviewed in the light of current understanding of weak interactions. Experimental methods and results regarding capture probabilities, capture ratios, and EC/Beta(+) ratios are summarized. Radiative electron capture is discussed, including both theory and experiment. Atomic wave function overlap and electron exchange effects are covered, as are atomic transitions that accompany nuclear electron capture. Tables are provided to assist the reader in determining quantities of interest for specific cases.

  17. Differential double capture cross sections in p+He collisions

    SciTech Connect

    Schulz, M.; Brand, J. A.; Vajnai, T.

    2007-02-15

    We have measured differential double capture cross sections for 15 to 150 keV p+He collisions. We also analyzed differential double to single capture ratios, where we find pronounced peak structures. An explanation of these structures probably requires a quantum-mechanical description of elastic scattering between the projectile and the target nucleus. Strong final-state correlations have a large effect on the magnitude of the double capture cross sections.

  18. Isotope separation by photoselective dissociative electron capture

    DOEpatents

    Stevens, Charles G. [Pleasanton, CA

    1978-08-29

    A method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, .sup.235 UF.sub.6 is separated from a UF.sub.6 mixture by selective excitation followed by dissociative electron capture into .sup.235 UF.sub.5 - and F.

  19. Isotope separation by photoselective dissociative electron capture

    DOEpatents

    Stevens, C.G.

    1978-08-29

    Disclosed is a method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, [sup 235]UF[sub 6] is separated from a UF[sub 6] mixture by selective excitation followed by dissociative electron capture into [sup 235]UF[sub 5]- and F. 2 figs.

  20. Double coupled electron shuttle

    NASA Astrophysics Data System (ADS)

    Prada, M.; Platero, G.

    2012-10-01

    A nanoshuttle consisting of two movable islands connected in series and integrated between two contacts is studied. We evaluate the electron transport through the system in the presence of a source-drain voltage with and without an rf excitation. We evaluate the response of the system in terms of the net direct current enhanced by the mechanical motion of the oscillators. An introduction to the charge stability diagram is given in terms of electrochemical potentials and mechanical displacements. The low capacitance of the islands allows the observation of Coulomb blockade even at room temperature. Using radio frequency excitations, the nonlinear dynamics of the system is studied. The oscillators can be tuned to unstable regions where mechanically assisted transfer of electrons can further increase the amplitude of motion, resulting of a net energy being pumped into the system. The resulting amplified response can be exploited to design a mechanical motion detector of nanoscale objects.

  1. EVOLUTION OF PROGENITORS FOR ELECTRON CAPTURE SUPERNOVAE

    SciTech Connect

    Takahashi, Koh; Umeda, Hideyuki; Yoshida, Takashi E-mail: umeda@astron.s.u-tokyo.ac.jp

    2013-07-01

    We provide progenitor models for electron capture supernovae (ECSNe) with detailed evolutionary calculation. We include minor electron capture nuclei using a large nuclear reaction network with updated reaction rates. For electron capture, the Coulomb correction of rates is treated and the contribution from neutron-rich isotopes is taken into account in each nuclear statistical equilibrium (NSE) composition. We calculate the evolution of the most massive super asymptotic giant branch stars and show that these stars undergo off-center carbon burning and form ONe cores at the center. These cores become heavier up to the critical mass of 1.367 M{sub Sun} and keep contracting even after the initiation of O+Ne deflagration. Inclusion of minor electron capture nuclei causes convective URCA cooling during the contraction phase, but the effect on the progenitor evolution is small. On the other hand, electron capture by neutron-rich isotopes in the NSE region has a more significant effect. We discuss the uniqueness of the critical core mass for ECSNe and the effect of wind mass loss on the plausibility of our models for ECSN progenitors.

  2. Electron capture in carbon dwarf supernovae

    NASA Technical Reports Server (NTRS)

    Mazurek, T. J.; Truran, J. W.; Cameron, A. G. W.

    1974-01-01

    The rates of electron capture on heavier elements under the extreme conditions predicted for dwarf star supernovae have been computed, incorporating modifications that seem to be indicated by present experimental results. An estimate of the maximum possible value of such rates is also given. The distribution of nuclei in nuclear statistical equilibrium has been calculated for the range of expected supernovae conditions, including the effects of the temperature dependence of nuclear partition functions. These nuclide abundance distributions are then used to compute nuclear equilibrium thermodynamic properties. The effects of the electron capture on such equilibrium matter are discussed. In the context of the 'carbon detonation' supernova model, the dwarf central density required to ensure core collapse to a neutron star configuration is found to be slightly higher than that obtained by Bruenn (1972) with the electron capture rates of Hansen (1966).-

  3. Laser-induced electron capture mass spectrometry

    PubMed

    Wang; Giese

    2000-02-15

    Two techniques are reported for detection of electrophorederivatized compounds by laser-induced electron capture time-of-flight mass spectrometry (LI-EC-TOF-MS). In both cases, a nitrogen laser is used to induce the electron capture. The analyte is deposited in a matrix consisting of a compound with a low ionization potential such as benzo[ghi]perylene in the first technique, where the electron for electron capture apparently comes from this matrix. In the second technique, the analyte is deposited on a silver surface in the absence of matrix. It seems that "monoenergetic" ions instantly desorb from the target surface in the latter case, since the peak width in the continuous extraction mode essentially matches the pulse width of the laser (4 ns). Ten picomoles of 3-O-(pentafluorobenzyl)-alpha-estradiol were detected at a S/N > or = 50, where the spot size of the laser was approximately 0.25% of the sample spot. It is attractive that simple conditions can enable sensitive detection of electrophores on routine TOF-MS equipment. The technique can be anticipated to broaden the range of analytes in both polarity and size that can be detected by EC-MS relative to the range for GC/EC-MS. PMID:10701262

  4. Electron capture decay in Jovian planets

    NASA Astrophysics Data System (ADS)

    Zito, R. R.; Schiferl, D.

    1987-12-01

    Following the commonly acknowledged fact that the decay of K-40 substantially contributes to the heating of planetary interiors, an examination is made of the possibility that interior heat in the Jovian planets and stars, where interior pressures may exceed 45 Mbar, may be generated by the pressure-accelerated electron capture decay of a variety of isotopes. The isotopes considered encompass K-40, V-50, Te-123, La-138, Al-26, and Cl-36.

  5. Electron capture from solids by positrons

    SciTech Connect

    Howell, R.

    1987-08-01

    The capture of electrons in solids is modified from that in gasses by several factors. The most important is the collective interaction of the electrons which results in a density of electron states in the solid in wide bands. Also the high density of electrons in many solids gives a high frequency of interaction as compared to gasses, and quickly destroys any electron-positron states in the metal matrix. Consequently, most positrons implanted in a metal will rapidly thermalize, and unless they reach the surface will annihilate with an electron in an uncorrelated state. Positronium formation from positrons scattered at a metal surface is analogous to ion neutralization however, most of the positronium comes from positrons passing through the surface from the bulk. The dominant motivation for studying positronium formation has been the hope that the distribution of the electrons at the surface would be obtained through the annihilation properties of positrons trapped at the surface or through analysis of the energy and angular distributions of the positronium emitted into the vacuum. These distributions have been measured and are included in this paper. 17 refs.

  6. Electron capture and fragmentation in Ar11+ + CO collisions

    NASA Astrophysics Data System (ADS)

    Ben-Itzhak, I.; Wells, E.; Stöckli, M. P.; Tawara, H.; Carnes, K. D.

    1997-01-01

    Collisions between 32.2, 130.5 and 570.5 keV Ar11+ ions and CO molecules have been studied using the Macdonald Laboratory CRYEBIS. Coincidence time of flight was used to detect all recoil ions originating from each molecule and a position sensitive detector was used to determine final projectile charge states. Single-and double-electron capture cross-sections are much larger than those for ionization at these collision energies. The dominant recoil channel associated with the Ar10+ final charge state is the CO+ molecular ion. The main ion-pair channel is the C+ + O+ dissociation of CO2+ while the relative yields of higher charge states of the transient COq+ fall off rapidly. The dissociated ions corresponding to charge states up to CO4+ were detected in coincidence with Ar10+ (and Ar9+), indicating that multielectron capture followed by autoionization occurs.

  7. Electron capture on iron group nuclei

    SciTech Connect

    Dean, D.J.; Chatterjee, L.; Strayer, M.R.; Dean, D.J.; Chatterjee, L.; Langanke, K.; Chatterjee, L.; Radha, P.B.

    1998-07-01

    We present Gamow-Teller strength distributions from shell model Monte Carlo studies of fp-shell nuclei that may play an important role in the precollapse evolution of supernovas. We then use these strength distributions to calculate the electron-capture cross sections and rates in the zero-momentum transfer limit. We also discuss the thermal behavior of the cross sections. We find large differences in these cross sections and rates when compared to the naive single-particle estimates. These differences need to be taken into account for improved modeling of the early stages of type-II supernova evolution. thinsp {copyright} {ital 1998} {ital The American Physical Society}

  8. Electron capture dissociation mass spectrometry of metallo-supramolecular complexes.

    PubMed

    Kaczorowska, Malgorzata A; Hotze, Anna C G; Hannon, Michael J; Cooper, Helen J

    2010-02-01

    The electron capture dissociation (ECD) of metallo-supramolecular dinuclear triple-stranded helicate Fe(2)L(3)(4+) ions was determined by Fourier transform ion cyclotron resonance mass spectrometry. Initial electron capture by the di-iron(II) triple helicate ions produces dinuclear double-stranded complexes analogous to those seen in solution with the monocationic metal centers Cu(I) or Ag(I). The gas-phase fragmentation behavior [ECD, collision-induced dissociation (CID), and infrared multiphoton dissociation (IRMPD)] of the di-iron double-stranded complexes, (i.e., MS(3) of the ECD product) was compared with the ECD, CID, and IRMPD of the Cu(I) and Ag(I) complexes generated from solution. The results suggest that iron-bound dimers may be of the form Fe(I)(2)L(2)(2+) and that ECD by metallo-complexes allows access, in the gas phase, to oxidation states and coordination chemistry that cannot be accessed in solution. PMID:20004114

  9. Can electron capture tell us the mass of the neutrino?

    NASA Astrophysics Data System (ADS)

    Faessler, Amand; Šimkovic, F.

    2016-04-01

    The neutrino masses are one of the most important open problems in particle physics. Presently major efforts are underway to measure the electron antineutrino-mass by the triton beta decay [1] and the effective Majorana neutrino mass by the double beta decay [2]. The best way to determine the neutrino mass by electron capture was assumed to be in {}163{Ho}. The total decay energy of the excited daughter atom has for all excitations the same upper energy limit of the Q-value minus the mass of the electron neutrino. Recently Robertson [3] claimed, that the excitation of the two-hole states makes the determination of the neutrino mass by this method practically impossible. But Faessler and Simkovic [4] showed, that the influence of the two-hole states is less than 1% near the Q-value, the area relevant for the determination of the neutrino mass. Even weaker are the contributions of the three-hole states [5]. The upper end of the calorimetric deexcitation spectrum of Dy is dominated by the highest energy one-hole resonance. With a Lorentzian profile of this resonance one has to fit after including the experimental sensitivity four parameters: (1) the neutrino mass, (2) the Q-value, (3) the width of the resonance and (4) its strength. This contribution discusses the problems of the determination of the neutrino mass by electron capture in {}163{Ho}. The conclusion of this work is, that the determination of the electron neutrino mass by electron capture in {}163{Ho} is difficult, but (probably) not impossible.

  10. Electron temperature differences and double layers

    NASA Technical Reports Server (NTRS)

    Chan, C.; Hershkowitz, N.; Lonngren, K. E.

    1983-01-01

    Electron temperature differences across plasma double layers are studied experimentally. It is shown that the temperature differences across a double layer can be varied and are not a result of thermalization of the bump-on-tail distribution. The implications of these results for electron thermal energy transport in laser-pellet and tandem-mirror experiments are also discussed.

  11. Efficient uranium capture by polysulfide/layered double hydroxide composites.

    PubMed

    Ma, Shulan; Huang, Lu; Ma, Lijiao; Shim, Yurina; Islam, Saiful M; Wang, Pengli; Zhao, Li-Dong; Wang, Shichao; Sun, Genban; Yang, Xiaojing; Kanatzidis, Mercouri G

    2015-03-18

    There is a need to develop highly selective and efficient materials for capturing uranium (normally as UO2(2+)) from nuclear waste and from seawater. We demonstrate the promising adsorption performance of S(x)-LDH composites (LDH is Mg/Al layered double hydroxide, [S(x)](2-) is polysulfide with x = 2, 4) for uranyl ions from a variety of aqueous solutions including seawater. We report high removal capacities (q(m) = 330 mg/g), large K(d)(U) values (10(4)-10(6) mL/g at 1-300 ppm U concentration), and high % removals (>95% at 1-100 ppm, or ∼80% for ppb level seawater) for UO2(2+) species. The S(x)-LDHs are exceptionally efficient for selectively and rapidly capturing UO2(2+) both at high (ppm) and trace (ppb) quantities from the U-containing water including seawater. The maximum adsorption coeffcient value K(d)(U) of 3.4 × 10(6) mL/g (using a V/m ratio of 1000 mL/g) observed is among the highest reported for U adsorbents. In the presence of very high concentrations of competitive ions such as Ca(2+)/Na(+), S(x)-LDH exhibits superior selectivity for UO2(2+), over previously reported sorbents. Under low U concentrations, (S4)(2-) coordinates to UO2(2+) forming anionic complexes retaining in the LDH gallery. At high U concentrations, (S4)(2-) binds to UO2(2+) to generate neutral UO2S4 salts outside the gallery, with NO3(-) entering the interlayer to form NO3-LDH. In the presence of high Cl(-) concentration, Cl(-) preferentially replaces [S4](2-) and intercalates into LDH. Detailed comparison of U removal efficiency of S(x)-LDH with various known sorbents is reported. The excellent uranium adsorption ability along with the environmentally safe, low-cost constituents points to the high potential of S(x)-LDH materials for selective uranium capture. PMID:25714654

  12. Neutronic effects on tungsten-186 double neutron capture

    NASA Astrophysics Data System (ADS)

    Garland, Marc Alan

    Rhenium-188, a daughter product of tungsten-188, is an isotope of great interest in therapeutic nuclear medicine, being used in dozens of laboratory and clinical investigations worldwide. Applications include various cancer therapy strategies, treatment of rheumatoid arthritis, prevention of restenosis following coronary artery angioplasty, and palliation of bone pain associated with cancer metastases. With its half-life of 17 hours, 2.12 MeV (maximum) beta-particle emission, chemical similarity to technetium-99m (the most widely used diagnostic radioisotope), and its availability in a convenient tungsten-188/rhenium-188 generator system, rhenium-188 is a superb candidate for a broad range of applications. Production of 188W is typically via double neutron capture by 186W in a high flux nuclear reactor, predominantly the High Flux Isotope Reactor at the Oak Ridge National Laboratory in Tennessee. Experience at HFIR has shown that production yields (measured in Ci of 188W produced per g of 186W target) decrease considerably as target size increases. While the phenomenon of neutron resonance self-shielding would be expected to produce such an effect, temperature effects on neutron flux distribution and neutron capture rates may also be involved. Experimental investigations of these phenomena have not been previously performed. The work presented in this thesis evaluates the factors that contribute to the decrease in 188W yield from both theoretical and experimental standpoints. Neutron self-shielding and temperature effects were characterized to develop a strategy for target design that would optimize production yield, an important factor in minimizing health care costs. It was determined that decrease in yield due to neutron self-shielding can be attributed to depletion of epithermal neutrons at resonant energies, most significantly within the initial 0.4 mm depth of the target. The results from these studies further show that 188W yield in the interior of the

  13. Electron-impact double ionization of magnesium

    SciTech Connect

    Ford, M.J.; El-Marji, B.; Doering, J.P.; Moore, J.H.; Coplan, M.A.; Cooper, J.W.

    1998-01-01

    Electron-impact double-ionization cross sections differential in the angles of the two ejected electrons have been measured at impact energies of 422 and 1052 eV. The energies of the ejected electrons were fixed at 100 eV each. The cross sections are very different at the two incident energies. At 1052 eV the ejected electrons are preferentially found in the forward direction with respect to the incident beam. At 422 eV they are found in the forward and backward directions with approximately equal probability. The 422-eV cross sections are largest when the incident-electron and ejected-electron momentum vectors lie in a common plane. The observations are discussed in the context of several models for double ionization. {copyright} {ital 1998} {ital The American Physical Society}

  14. Electron capture processes in Li2+ + H collisions

    NASA Astrophysics Data System (ADS)

    Yan, Ling Ling; Liu, Ling; Wang, Jian Guo; Janev, Ratko K.; Buenker, Robert J.

    2015-01-01

    The electron capture processes in Li2 + + H collisions have been investigated by using the quantum-mechanical molecular-orbital close-coupling method and the two-center atomic-orbital close-coupling method in the energy ranges of 10-8-10 keV/u and 0.1-300 keV/u, respectively. The capture to singlet and triplet systems of states of Li+(1 s,n l 2S + 1L) is considered separately. Total, n,S-resolved and n,l,S-resolved electron capture cross sections are calculated and compared with the results of available experimental and theoretical studies. The present calculations show that the n = 2 shell of Li+ is the main capture channel for all energies considered in both the singlet and triplet case. While for collision energies E> 5 keV/u, the cross sections for capture to the n = 2 manifold are of the same order of magnitude for both the singlet and triplet states (with the 2 p capture cross section being dominant), for energies below ~5 keV/u the cross sections for capture to the n = 2 triplet manifold is significantly (more than three orders of magnitude at 0.1 keV/u) larger than that for capture to the n = 2 singlet manifold of states (with the 2 s capture cross section being dominant). The capture dynamics at low collision energies is discussed in considerable detail, revealing the important role of rotational couplings in population of l> 0 capture states. The elastic scattering processes have been studied as well in the energy range of 10-8-1 keV/u. The calculated elastic scattering cross section is much larger than the electron capture cross section in both the singlet and triplet case. However, as the collision energy increases, the difference between the elastic and electron capture cross sections decreases rapidly.

  15. Physics Reach of Electron-Capture Neutrino Beams

    NASA Astrophysics Data System (ADS)

    Bernabeu, J.; Burguet-Castell, J.; Espinoza, C.; Lindroos, M.

    2006-05-01

    To complete the picture of neutrino oscillations two fundamental parameters need to be measured, θ and δ. The next generation of long baseline neutrino oscillation experiments -superbeams, betabeams and neutrino factories- indeed take aim at measuring them. Here we explore the physics reach of a new candidate: an electron-capture beam. Emphasis is made on its feasibility thanks to the recent discovery of nuclei that decay fast through electron capture, and on the interplay with a betabeam (its closest relative).

  16. To what extent can highly charged ions keep captured electrons

    SciTech Connect

    Morgenstern, R. )

    1993-06-05

    In collisions between highly charged ions and atomic or molecular targets three phases can be distinguished: an initial capture into nonstationary states, a rearrangement of the captured electrons, and finally a decay by means of photon or electron emission. To understand the final result of such collisions one has to understand the processes in each phase. Several examples of recent investigations are discussed which shed light on the processes during these phases.

  17. Comparison of Electronic Data Capture (EDC) with the Standard Data Capture Method for Clinical Trial Data

    PubMed Central

    Walther, Brigitte; Hossin, Safayet; Townend, John; Abernethy, Neil; Parker, David; Jeffries, David

    2011-01-01

    Background Traditionally, clinical research studies rely on collecting data with case report forms, which are subsequently entered into a database to create electronic records. Although well established, this method is time-consuming and error-prone. This study compares four electronic data capture (EDC) methods with the conventional approach with respect to duration of data capture and accuracy. It was performed in a West African setting, where clinical trials involve data collection from urban, rural and often remote locations. Methodology/Principal Findings Three types of commonly available EDC tools were assessed in face-to-face interviews; netbook, PDA, and tablet PC. EDC performance during telephone interviews via mobile phone was evaluated as a fourth method. The Graeco Latin square study design allowed comparison of all four methods to standard paper-based recording followed by data double entry while controlling simultaneously for possible confounding factors such as interview order, interviewer and interviewee. Over a study period of three weeks the error rates decreased considerably for all EDC methods. In the last week of the study the data accuracy for the netbook (5.1%, CI95%: 3.5–7.2%) and the tablet PC (5.2%, CI95%: 3.7–7.4%) was not significantly different from the accuracy of the conventional paper-based method (3.6%, CI95%: 2.2–5.5%), but error rates for the PDA (7.9%, CI95%: 6.0–10.5%) and telephone (6.3%, CI95% 4.6–8.6%) remained significantly higher. While EDC-interviews take slightly longer, data become readily available after download, making EDC more time effective. Free text and date fields were associated with higher error rates than numerical, single select and skip fields. Conclusions EDC solutions have the potential to produce similar data accuracy compared to paper-based methods. Given the considerable reduction in the time from data collection to database lock, EDC holds the promise to reduce research-associated costs

  18. Electron capture from circular Rydberg atoms

    SciTech Connect

    Hansen, S.B.; Ehrenreich, T.; Horsdal-Pedersen, E. ); MacAdam, K.B. ); Dube, L.J. )

    1993-09-06

    Capture cross sections for circular Rydberg states have been measured as a function of the angle, [ital cphi], between ion velocity and angular momentum of the circular orbital. The system studied is 2.5 keV [sup 23]Na[sup +] on Li(1[ital s][sup 2],[ital nlm]) with [ital n]=25, [ital l]=[ital n][minus]1, and [ital m]=+[ital l], where [ital m] is defined relative to a weak, external magnetic field. A strong dependence on [ital cphi] is found. It is expected that studies such as the present will lead to an improved understanding of the three-body problem in the region of sufficiently large quantum numbers and impact velocities for classical physics to be accurate.

  19. Electron emission from single-electron capture with simultaneous single-ionization reactions in 30-keV/u He{sup 2+}-on-argon collisions

    SciTech Connect

    Ma, X.; Zhang, S. F.; Zhu, X. L.; Feng, W. T.; Li, B.; Liu, H. P.; Zhang, R. T.; Guo, D. L.; Yan, S. C.; Zhang, P. J.; Wang, Q.; Li, C. Y.; Wang, J. G.

    2011-05-15

    Electron emission from the single-electron capture with simultaneous single ionization in 30 keV/u He{sup 2+} on argon was investigated using a reaction microscope, providing the electron energy spectra and momentum distributions. Intensive peaks for electrons with near-zero kinetic energies have been observed. It is demonstrated that mechanisms contributing to the electron emission include direct transfer ionization (DTI), double-electron capture with autoionization (DECA), and single-electron capture with autoionization (SECA) of target. Comparison of resonance energies shows that Ar{sup +} ions in SECA decay mainly through the 3s3p{sup 5}3d states by emitting Auger electrons, and He** in DECA decay through the 2l2l' states. The dependence of electron emission on the transverse momentum exchange has been studied. In the transfer ionization channel studied here, the DTI process dominates the electron emission, and no saddle point electron mechanism has been found.

  20. Modelling low-energy electron-molecule capture processes.

    PubMed

    Dashevskaya, E I; Litvin, I; Nikitin, E E; Troe, J

    2008-03-01

    Cross sections and rate coefficients for capture of low-energy electrons with polar and polarizable target molecules are calculated in the framework of Fabrikant and Hotop's extended version of the Vogt-Wannier model and an extension of this approach is given in the present article. Analytical approximations are derived in order to facilitate the application to experiments. A comparison with a selection of experimental electron attachment rate coefficients provides insight into the competition between anion formation through electron capture and scattering processes which do not follow this pathway. PMID:18292861

  1. Single electron capture for K+-H2

    NASA Astrophysics Data System (ADS)

    Fuentes, B. E.; Alarcon, F. B.; Martinez, H.; Yousif, F. B.

    2013-04-01

    Absolute cross section of electron capture for the K+-H2 pair employing beam collision spectroscopy method for 0.4 to 4 keV energy were measured. Capture cross section increased with increase in energy. Present results below 2 keV overlap with previously measured data of other investigators and extend down in energy to 400 eV. Interpretation of the data (below 2 keV) was made on the frame work quasimolecular representation.

  2. Electron capture by finite-size polarizable molecules and clusters.

    PubMed

    Nikitin, E E; Troe, J

    2010-08-21

    The effects of finite molecular target size are investigated for partial-wave selected capture of electrons by isotropically polarizable molecules and clusters within a generalized Vogt-Wannier model. It is shown how expressions for partial-wave selected capture probabilities of zero-size targets from Dashevskaya et al. (Phys. Chem. Chem. Phys., 2009, 11, 9364) can be modified to account for finite target sizes of the molecules and clusters. The transition from quantum to classical, from single- to multiple- and all-wave, behaviour of capture probabilities, cross sections, and rate constants is illustrated. PMID:20532307

  3. Electron-capture delayed fission properties of 244Es

    SciTech Connect

    Shaughnessy, Dawn A.; Gregorich, Kenneth E.; Adams, Jeb L.; Lane, Michael R.; Laue, Carola A.; Lee, Diana M.; McGrath, Christopher A.; Ninov, Victor; Patin, Joshua B.; Strellis, Dan A.; Sylwester, Eric R.; Wilk, Philip A.; Hoffman, Darleane C.

    2001-03-16

    Electron-capture delayed fission was observed in {sup 244}Es produced via the {sup 237}Np({sup 12}C,5n){sup 244}Es reaction at 81 MeV (on target) with a production cross section of 0.31{+-}0.12 {micro}b. The mass-yield distribution of the fission fragments is highly asymmetric. The average preneutron-emission total kinetic energy of the fragments was measured to be 186{+-}19 MeV. Based on the ratio of the number of fission events to the measured number of {alpha} decays from the electron-capture daughter {sup 244}Cf (100% {alpha} branch), the probability of delayed fission was determined to be (1.2{+-}0.4) x 10{sup -4}. This value for the delayed fission probability fits the experimentally observed trend of increasing delayed fission probability with increasing Q value for electron-capture.

  4. Coronal Electron Confinement by Double Layers

    NASA Astrophysics Data System (ADS)

    Li, T. C.; Drake, J. F.; Swisdak, M.

    2013-12-01

    In observations of flare-heated electrons in the solar corona, a longstanding problem is the unexplained prolonged lifetime of the electrons compared to their transit time across the source. This suggests confinement. Recent particle-in-cell (PIC) simulations, which explored the transport of pre-accelerated hot electrons through ambient cold plasma, showed that the formation of a highly localized electrostatic potential drop, in the form of a double layer (DL), significantly inhibited the transport of hot electrons. The effectiveness of confinement by a DL is linked to the strength of the DL as defined by its potential drop. In this work, we investigate the scaling of the DL strength with the hot electron temperature by PIC simulations and find a linear scaling. We demonstrate that the strength is limited by the formation of parallel shocks. Based on this, we analytically determine the maximum DL strength, and also find a linear scaling with the hot electron temperature. The DL strength obtained from the analytic calculation is comparable to that from the simulations. At the maximum strength, the DL is capable of confining a significant fraction of hot electrons in the source.

  5. Theory of nuclear excitation by electron capture for heavy ions

    SciTech Connect

    Palffy, Adriana; Scheid, Werner; Harman, Zoltan

    2006-01-15

    We investigate the resonant process of nuclear excitation by electron capture (NEEC), in which a continuum electron is captured into a bound state of an ion with the simultaneous excitation of the nucleus. In order to derive the cross section a Feshbach projection operator formalism is introduced. Nuclear states and transitions are described by a nuclear collective model and making use of experimental data. Transition rates and total cross sections for NEEC followed by the radiative decay of the excited nucleus are calculated for various heavy-ion collision systems.

  6. Simple electron beam guiding system including automatic capture circuitry

    NASA Astrophysics Data System (ADS)

    Stein, W.; Schulenburg, M.; Freund, F.

    1980-08-01

    The spatial stability of the point of impact of an electron beam is a stringent requirement in some experiments such as soft x-ray spectroscopy using a focussing curved crystal spectrometer. The occasinally poor design of moderately priced electron guns, thermal instabilities, electromagnetic stray fields and so on, make spot stabilization an arduous task. The problem can be solved to some extent by a simple electron beam guiding system: a small fraction of the electron beam is captured by a metal wire mounted in the vicinity of the target. The beam position is fixed, if this fraction is controlled by a feedback loop via the deflection plates of the gun.

  7. Electron capture imaging of two-dimensional materials

    NASA Astrophysics Data System (ADS)

    Labaigt, G.; Dubois, A.; Hansen, J. P.

    2014-06-01

    We demonstrate that electron transfer induced by fast ion impact can be used as an imaging technique of two-dimensional materials. Applied to a keV proton beam passing through a graphene surface, it is shown that coherent single-electron capture gives a sub-ångström-scale spatial resolution image of the electronic structure of a single sheet. This imaging scheme is shown to be particularly effective, resolving missing atoms (vacancies) in the lattice, in a narrow projectile 5-10-keV energy region, where the capture probability exhibits a minimum at the center of the hexagonal cells. This geometry-dependent phenomenon is caused by the coupling dynamic between the initial state and a multi-electron entangled one-hole state and is therefore highly sample selective.

  8. Single and double capture in F9+ + Ar collisions: Comparison of total capture with capture occurring from the Ar K shell

    NASA Astrophysics Data System (ADS)

    La Mantia, David; Kumara, Nuwan; Kayani, Asghar; Simon, Anna; Tanis, John

    2016-05-01

    Total cross sections for single and double capture, as well as the corresponding cross sections for capture resulting in the emission of an Ar K x ray, were measured. This work was performed at Western Michigan University with the use of the tandem Van de Graaff accelerator. A 45 MeV beam of fully-stripped fluorine ions was collided with argon gas molecules in a differentially pumped cell. Surface barrier detectors were used to observe the charge changed projectiles and a Si(Li) x-ray detector, placed at 90o to the incident beam, were used to measure coincidences with Ar K x rays. The total capture cross sections are compared to previously measured cross sections in the existing literature. The coincidence cross sections, considerably smaller than the total cross sections, are found to be nearly equal for single and double capture in contrast to the total cross sections, which vary by about an order of magnitude. Possible reasons for this behavior are discussed. Supported in part by the NSF.

  9. Electron-capture supernovae exploding within their progenitor wind

    NASA Astrophysics Data System (ADS)

    Moriya, Takashi J.; Tominaga, Nozomu; Langer, Norbert; Nomoto, Ken'ichi; Blinnikov, Sergei I.; Sorokina, Elena I.

    2014-09-01

    The most massive stars on the asymptotic giant branch (AGB), or the so-called super-AGB stars, are thought to produce supernovae triggered by electron captures in their degenerate O+Ne+Mg cores. Super-AGB stars are expected to have slow winds with high mass-loss rates, so their circumstellar density is high. The explosions of super-AGB stars are therefore presumed to occur in this dense circumstellar environment. We provide the first synthetic light curves for such events by exploding realistic electron-capture supernova progenitors within their super-AGB winds. We find that the early light curve - that is, before the recombination wave reaches the bottom of the hydrogen-rich envelope of supernova ejecta (the plateau phase) - is not affected by the dense wind. However, after the luminosity drop following the plateau phase, the luminosity remains much higher when the super-AGB wind is taken into account. We compare our results to the historical light curve of SN 1054, the progenitor of the Crab Nebula, and show that the explosion of an electron-capture supernova within an ordinary super-AGB wind can explain the observed light curve features. We conclude that SN 1054 could have been a Type IIn supernova without any extra extreme mass loss, which was previously suggested to be necessary to account for its early high luminosity. We also show that our light curves match Type IIn supernovae with an early plateau phase or the so-called Type IIn-P supernovae, and suggest that they are electron-capture supernovae within super-AGB winds. Although some electron-capture supernovae can be bright in the optical spectral range due to the large progenitor radius, their X-ray luminosity from the interaction does not necessarily get as bright as other Type IIn supernovae whose optical luminosities are also powered by the interaction. Thus, we suggest that optically bright X-ray-faint Type IIn supernovae can emerge from electron-capture supernovae. Optically faint Type IIn supernovae

  10. Does Electron Capture Dissociation Cleave Protein Disulfide Bonds?

    PubMed Central

    Ganisl, Barbara; Breuker, Kathrin

    2012-01-01

    Peptide and protein characterization by mass spectrometry (MS) relies on their dissociation in the gas phase into specific fragments whose mass values can be aligned as ‘mass ladders’ to provide sequence information and to localize possible posttranslational modifications. The most common dissociation method involves slow heating of even-electron (M+n H)n+ ions from electrospray ionization by energetic collisions with inert gas, and cleavage of amide backbone bonds. More recently, dissociation methods based on electron capture or transfer were found to provide far more extensive sequence coverage through unselective cleavage of backbone N–Cα bonds. As another important feature of electron capture dissociation (ECD) and electron transfer dissociation (ETD), their unique unimolecular radical ion chemistry generally preserves labile posttranslational modifications such as glycosylation and phosphorylation. Moreover, it was postulated that disulfide bond cleavage is preferred over backbone cleavage, and that capture of a single electron can break both a backbone and a disulfide bond, or even two disulfide bonds between two peptide chains. However, the proposal of preferential disulfide bond cleavage in ECD or ETD has recently been debated. The experimental data presented here reveal that the mechanism of protein disulfide bond cleavage is much more intricate than previously anticipated. PMID:24363980

  11. Electron capture from Ni surface resulting from H+ ion impact

    NASA Astrophysics Data System (ADS)

    Suzuki, Reiko; Suzuki, Reiko; Sato, Hiroshi; Kimura, Mineo

    1998-10-01

    Electron capture from Cu and Co surfaces by H+ and He+ ion bombardment has been investigated theoretically by using the molecular representation. Since an experimental condition was that the incoming particle was introduced on the surface with a large angle, the binary collision would be satisfied. We have obtained electronic states of the colliding pair by the ALCHEMY, and the scattering dynamics was solved by using the semiclassical close coupling treatment. We have included trajectories of compete recoils of the projectile through the coupling of electronic and nuclear motions. The preliminary result obtained shed much light on the understanding of the experimental finding.

  12. Absolute cross sections for electron loss, electron capture, and multiple ionization in collisions of Li2+ with argon

    NASA Astrophysics Data System (ADS)

    Losqui, A. L. C.; Zappa, F.; Sigaud, G. M.; Wolff, W.; Sant'Anna, M. M.; Santos, A. C. F.; Luna, H.; Melo, W. S.

    2014-02-01

    Exclusive absolute cross sections for the electron loss and capture processes, accompanied by target multiple ionization and pure target multiple ionization, as well as total electron loss and capture cross sections, in collisions of Li2+ with Ar have been measured in the 0.5-3.5 MeV energy range. The experimental data of the total electron loss cross section are compared with theoretical results based on the plane-wave Born approximation and the free-collision model, and with the available experimental data. Some discrepancies are observed when comparing the experimental data with the theoretical models, which can be attributed to the competitive mechanisms that lead to electron loss. The dependences of the single-capture and transfer-ionization processes on the projectile charge state are similar to those observed for collisions between other low-charged light ions and noble-gas targets. The same behaviour is observed when one compares the present data for the single- and double-ionization cross sections with those for He2+ projectiles on Ar. These facts indicate that the dynamics of the collision does not seem to depend on the projectile species, so that few-electron projectiles may act as structureless point charges in the intermediate- to high-velocity regime.

  13. Dynamics of R.F. Captured Electron Cooled Proton Beams

    SciTech Connect

    Kells, W.; Mills, F.;

    1983-01-01

    In the course of electron cooling experiments at the Electron Cooling Ring (ECR) at Fermilab, several peculiar features of the longitudinal phase space of cold protons (200 MeV) captured in R.F. buckets were observed. Here we present the experimental facts, present a simple theory, and summarize computer simulation results which support the theory and facts. The experimental apparatus and measurement techniques have been described elsewhere. R.F. bunching was achieved with a single PPA, loaded cavity gap driven at harmonic number 6({approx} 7.56 MHz) of the revolution frequency. R.F. voltage could be developed across this gap sufficient to entirely capture even the uncooled circulating proton beam ({delta}p/p FWHM = 0.17%).

  14. Proton emission following multiple electron capture in slow N{sup 7+}+HCl collisions

    SciTech Connect

    Fremont, F.; Martina, D.; Kamalou, O.; Sobocinski, P.; Chesnel, J.-Y.; McNab, I.R.; Bennett, F.R.

    2005-04-01

    Collisions between 98-keV N{sup 7+} ions and a HCl target have been investigated experimentally. The kinetic-energy distribution of fragment H{sup +} ions originating from multiple electron capture was detected at angles in the range 20 deg. -160 deg. with respect to the incident beam direction. Proton energies as large as 100 eV were observed, and calculations made in the simple Coulomb explosion model suggest that up to seven target electrons may be involved during the collision. Using the Landau-Zener model, we show that the N{sup 7+} projectile mainly captures outer-shell electrons from HCl. From the experimental data we derived multiple-capture cross sections which we compared with results from a model calculation made using the classical over-barrier model and also with a semiempirical scaling law. For the specific case of double capture, several structures appeared, which were assigned using ab initio calculations to states of HCl{sup 2+}.

  15. Electron-capture delayed fission properties of {sup 242}Es

    SciTech Connect

    Shaughnessy, D. A.; Adams, J. L.

    2000-04-01

    Electron-capture delayed fission of {sup 242}Es produced via the {sup 233}U({sup 14}N,5n){sup 242}Es reaction at 87 MeV (on target) was observed to decay with a half-life of 11{+-}3 s, consistent with the reported {alpha}-decay half-life of {sup 242}Es of 16{sub -4}{sup +6} s. The mass-yield distribution of the fission fragments is highly asymmetric. The average pre-neutron emission total kinetic energy of the fragments was measured to be 183{+-}18 MeV. Based on the ratio of the measured number of fission events to the measured number of {alpha} decays from the electron-capture daughter {sup 242}Cf (100% {alpha} branch), the probability of delayed fission was determined to be 0.006{+-}0.002. This value for the delayed fission probability fits the experimental trend of increasing delayed fission probability with increasing Q value for electron capture. (c) 2000 The American Physical Society.

  16. Flexible CNT-array double helices Strain Sensor with high stretchability for Motion Capture.

    PubMed

    Li, Cheng; Cui, Ya-Long; Tian, Gui-Li; Shu, Yi; Wang, Xue-Feng; Tian, He; Yang, Yi; Wei, Fei; Ren, Tian-Ling

    2015-01-01

    Motion capture is attracting more and more attention due to its potential wide applications in various fields. However, traditional methods for motion capture still have weakness such as high cost and space consuming. Based on these considerations, a flexible, highly stretchable strain sensor with high gauge factor for motion capture is fabricated with carbon nanotube (CNT) array double helices as the main building block. Ascribed to the unique flexible double helical CNT-array matrix, the strain sensor is able to measure strain up to 410%, with low hysteresis. Moreover, a demonstration of using this strain sensor for capture hand motion and to control a mechanical hand in real time is also achieved. A model based on finite difference method is also made to help understand the mechanism of the strain sensors. Our work demonstrates that strain sensors can measure very large strain while maintaining high sensitivity, and the motion capture based on this strain sensor is expected to be less expensive, more convenient and accessible. PMID:26530904

  17. Flexible CNT-array double helices Strain Sensor with high stretchability for Motion Capture

    NASA Astrophysics Data System (ADS)

    Li, Cheng; Cui, Ya-Long; Tian, Gui-Li; Shu, Yi; Wang, Xue-Feng; Tian, He; Yang, Yi; Wei, Fei; Ren, Tian-Ling

    2015-11-01

    Motion capture is attracting more and more attention due to its potential wide applications in various fields. However, traditional methods for motion capture still have weakness such as high cost and space consuming. Based on these considerations, a flexible, highly stretchable strain sensor with high gauge factor for motion capture is fabricated with carbon nanotube (CNT) array double helices as the main building block. Ascribed to the unique flexible double helical CNT-array matrix, the strain sensor is able to measure strain up to 410%, with low hysteresis. Moreover, a demonstration of using this strain sensor for capture hand motion and to control a mechanical hand in real time is also achieved. A model based on finite difference method is also made to help understand the mechanism of the strain sensors. Our work demonstrates that strain sensors can measure very large strain while maintaining high sensitivity, and the motion capture based on this strain sensor is expected to be less expensive, more convenient and accessible.

  18. Flexible CNT-array double helices Strain Sensor with high stretchability for Motion Capture

    PubMed Central

    Li, Cheng; Cui, Ya-Long; Tian, Gui-Li; Shu, Yi; Wang, Xue-Feng; Tian, He; Yang, Yi; Wei, Fei; Ren, Tian-Ling

    2015-01-01

    Motion capture is attracting more and more attention due to its potential wide applications in various fields. However, traditional methods for motion capture still have weakness such as high cost and space consuming. Based on these considerations, a flexible, highly stretchable strain sensor with high gauge factor for motion capture is fabricated with carbon nanotube (CNT) array double helices as the main building block. Ascribed to the unique flexible double helical CNT-array matrix, the strain sensor is able to measure strain up to 410%, with low hysteresis. Moreover, a demonstration of using this strain sensor for capture hand motion and to control a mechanical hand in real time is also achieved. A model based on finite difference method is also made to help understand the mechanism of the strain sensors. Our work demonstrates that strain sensors can measure very large strain while maintaining high sensitivity, and the motion capture based on this strain sensor is expected to be less expensive, more convenient and accessible. PMID:26530904

  19. Scalable sensing electronics towards a motion capture suit

    NASA Astrophysics Data System (ADS)

    Xu, Daniel; Gisby, Todd A.; Xie, Shane; Anderson, Iain A.

    2013-04-01

    Being able to accurately record body motion allows complex movements to be characterised and studied. This is especially important in the film or sport coaching industry. Unfortunately, the human body has over 600 skeletal muscles, giving rise to multiple degrees of freedom. In order to accurately capture motion such as hand gestures, elbow or knee flexion and extension, vast numbers of sensors are required. Dielectric elastomer (DE) sensors are an emerging class of electroactive polymer (EAP) that is soft, lightweight and compliant. These characteristics are ideal for a motion capture suit. One challenge is to design sensing electronics that can simultaneously measure multiple sensors. This paper describes a scalable capacitive sensing device that can measure up to 8 different sensors with an update rate of 20Hz.

  20. Kinematic Isotope Effects in Low Energy Electron Capture

    SciTech Connect

    Stancil, P.C.; Zygelman, B.

    1995-08-21

    The replacement of hydrogen with its isotope deuterium, in collisions with multiply charged ions, is shown to lead to a suppression of total charge transfer cross sections at collision energies much higher than previously thought. We demonstrate, using a fully quantal calculation of electron capture in collisions of N{sup 4+}(2{ital s}) with H(1{ital s}) and D(1{ital s}), that this isotope effect is significant for capture into the N{sup 3+}(3{ital d}) states at collision energies approaching 10 eV/amu. Estimates of the magnitude of the effect, using the semiclassical Landau-Zener-Stueckelberg model, are made for several multiply charged systems.

  1. Electron Capture Dissociation of Trivalent Metal Ion-Peptide Complexes

    NASA Astrophysics Data System (ADS)

    Flick, Tawnya G.; Donald, William A.; Williams, Evan R.

    2013-02-01

    With electrospray ionization from aqueous solutions, trivalent metal ions readily adduct to small peptides resulting in formation of predominantly (peptide + MT - H)2+, where MT = La, Tm, Lu, Sm, Ho, Yb, Pm, Tb, or Eu, for peptides with molecular weights below ~1000 Da, and predominantly (peptide + MT)3+ for larger peptides. ECD of (peptide + MT - H)2+ results in extensive fragmentation from which nearly complete sequence information can be obtained, even for peptides for which only singly protonated ions are formed in the absence of the metal ions. ECD of these doubly charged complexes containing MT results in significantly higher electron capture efficiency and sequence coverage than peptide-divalent metal ion complexes that have the same net charge. Formation of salt-bridge structures in which the metal ion coordinates to a carboxylate group are favored even for (peptide + MT)3+. ECD of these latter complexes for large peptides results in electron capture by the protonation site located remotely from the metal ion and predominantly c/ z fragments for all metals, except Eu3+, which undergoes a one electron reduction and only loss of small neutral molecules and b/ y fragments are formed. These results indicate that solvation of the metal ion in these complexes is extensive, which results in the electrochemical properties of these metal ions being similar in both the peptide environment and in bulk water.

  2. Electron capture by bare ions on water molecules

    NASA Astrophysics Data System (ADS)

    Rivarola, Roberto; Montenegro, Pablo; Monti, Juan; Fojón, Omar

    2016-05-01

    Single electron capture from water molecules by impact of bare ions is theoretically investigated at intermediate and high collision energies. This reaction is of fundamental importance to determine the deposition of energy in biological matter irradiated with ion beams (hadrontherapy), dominating other ionizing processes of the target at low-intermediate impact velocities and giving principal contributions to the energetic region where electronic stopping power maximizes. The dynamics of the interaction between the aggregates is described within the one active-electron continuum distorted wave-eikonal initial state theory. The orbitals of the target in the ground state are represented using the approximate self-consistent complete neglect of differential orbitals (SC-CNDO) model. The contribution of different molecular orbitals on the partial cross sections to selected n-principal quantum number projectile states is discriminated as well as the collaboration of these n-states on total cross sections. The latter ones are dominated by capture to n=1 states at high enough energies decreasing their contribution as n increases.

  3. Electron capture acceleration channel in a slit laser beam

    SciTech Connect

    Wang, P. X.; Scheid, W.; Ho, Y. K.

    2007-03-12

    Using numerical simulations, the authors find that the electrons can be captured and accelerated to high energies (GeV) in a slit laser beam with an intensity of I{lambda}{sup 2}{approx}10{sup 20} W/cm{sup 2} {mu}m{sup 2}, where {lambda} is the laser wavelength in units of {mu}m. The range of the optimum incident energy is very wide, even up to GeV. These results are of interest for experiments because the relatively low intensity can be achieved with present chirped pulse amplification technique and a wide range of incident energies means that a multistage acceleration is possible.

  4. Isomer Triggering via Nuclear Excitation by Electron Capture

    SciTech Connect

    Palffy, Adriana; Evers, Joerg; Keitel, Christoph H.

    2007-10-26

    Triggering of long-lived nuclear isomeric states via coupling to the atomic shells in the process of nuclear excitation by electron capture (NEEC) is studied. NEEC occurring in highly charged ions can excite the isomeric state to a triggering level that subsequently decays to the ground state. We present total cross sections for NEEC isomer triggering considering experimentally confirmed low-lying triggering levels and reaction rates based on realistic experimental parameters in ion storage rings. A comparison with other isomer triggering mechanisms shows that, among these, NEEC is the most efficient.

  5. Decay curve study in a standard electron capture decay

    SciTech Connect

    Nishimura, D.; Fukuda, M.; Kisamori, K.; Kuwada, Y.; Makisaka, K.; Matsumiya, R.; Matsuta, K.; Mihara, M.; Takagi, A.; Yokoyama, R.; Izumikawa, T.; Ohtsubo, T.; Suzuki, T.; Yamaguchi, T.

    2010-05-12

    We have searched for a time-modulated decay in a standard electron capture experiment for {sup 140}Pr, in order to confirm a report from GSI, where an oscillatory decay has been observed for hydrogen-like {sup 140}Pr and {sup 142}Pm ions in the cooler storage ring. {sup 140}Pr has been produced with the {sup 140}Ce(p, n) reaction by a pulsed proton beam accelerated from the Van de Graaff accelerator at Osaka University. Resultant time dependence of the K{sub a}lpha and K{sub b}eta X-ray intensities from the daughter shows no oscillatory behavior.

  6. Electron capture induced dissociation of nucleotide anions in water nanodroplets.

    PubMed

    Liu, B; Haag, N; Johansson, H; Schmidt, H T; Cederquist, H; Brondsted Nielsen, S; Zettergren, H; Hvelplund, P; Manil, B; Huber, B A

    2008-02-21

    We have studied the outcome of collisions between the hydrated nucleotide anion adenosine 5'-monophosphate (AMP) and sodium. Electron capture leads to hydrogen loss as well as water evaporation regardless of the initial number m of water molecules attached to the parent ion (m< or =16). The yield of dianions with microsecond lifetimes increases strongly with m, which is explained from dielectric screening of the two charges by the water nanodroplet. For comparison, collision induced dissociation results in water losses with no or very little damage of the AMP molecule itself. PMID:18298174

  7. Cross sections of electron capture and electron capture ionization versus the impact parameter in collisions of a proton with multielectron atoms

    NASA Astrophysics Data System (ADS)

    Afrosimov, V. V.; Basalaev, A. A.; Ogurtsov, G. N.; Panov, M. N.

    2014-05-01

    The absolute differential cross sections of scattering of hydrogen atoms resulting from an electron capture and an electron capture ionization are measured for collisions of 4.5- and 11-keV protons with argon and xenon atoms. The range of scattering angles is 0°-2°. From the scattering differential cross section found experimentally, the probabilities of single-electron capture and electron capture ionization as a function of the impact parameter are calculated. The dependences of the incident particle scattering angle on the impact parameter (deviation function) for interactions with Ar and Xe atoms are calculated in terms of classical mechanics using the Moliére—Yukawa potential to describe the interaction of atomic particles. Analysis is given to the probabilities of electron capture and electron capture ionization versus the impact parameter and to the distribution of the electron density on different electron shells in a target atom versus a distance to the core. It is concluded that only electrons from the outer shell of the target atom are involved in the process of electron capture ionization. The cross section of electron capture ionization is calculated in the proton energy range 5-20 keV.

  8. Ionization of water by (20-150)-keV protons: Separation of direct-ionization and electron-capture processes

    SciTech Connect

    Gobet, F.; Eden, S.; Coupier, B.; Tabet, J.; Farizon, B.; Farizon, M.; Gaillard, M.J.; Carre, M.; Ouaskit, S.; Maerk, T. D.; Scheier, P.

    2004-12-01

    Mass analyzed product ions have been detected in coincidence with the projectile following the ionization of water by proton impact. Measurement of the projectile charge state postcollision enables the different ionization processes to be identified: direct ionization, single electron capture, and double electron capture. A complete set of partial and total absolute cross sections is reported for the direct ionization and electron capture processes initiated by proton collisions at 20-150 keV. The cross sections for the direct ionization of H{sub 2}O by proton impact are compared with previous electron impact results [Straub et al., J. Chem. Phys. 108, 109 (1998)].

  9. Sensitivity to electronics error in coupled double quantum dot qubits

    NASA Astrophysics Data System (ADS)

    Nielsen, Erik; Muller, Richard; Carroll, Malcolm

    2011-03-01

    Reducing the effects of electronics control error in double quantum dot (DQD) quantum bits (qubit) is a central challenge to the creation of a solid-state quantum computing architecture. We investigate a system of capacitively coupled DQDs which implement a variant of the controlled phase gate when using each DQD as a singlet-triplet qubit. We identify regimes in which the gate action is more robust to sources of noise such as error around the applied bias point due to electronics or charge noise. Energy spectra are found using a configuration interaction (CI) method that accurately captures the (2,0) configuration of the DQD system, which is important for operating in these potentially low-noise regimes. This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  10. Attosecond metrology: from electron capture to future signal processing

    NASA Astrophysics Data System (ADS)

    Krausz, Ferenc; Stockman, Mark I.

    2014-03-01

    The accurate measurement of time lies at the heart of experimental science, and is relevant to everyday life. Extending chronoscopy to ever shorter timescales has been the key to gaining real-time insights into microscopic phenomena, ranging from vital biological processes to the dynamics underlying high technologies. The generation of isolated attosecond pulses in 2001 allowed the fastest of all motions outside the nucleus -- electron dynamics in atomic systems -- to be captured. Attosecond metrology has provided access to several hitherto immeasurably fast electron phenomena in atoms, molecules and solids. The fundamental importance of electron processes for the physical and life sciences, technology and medicine has rendered the young field of attosecond science one of the most dynamically expanding research fields of the new millennium. Here, we review the basic concepts underlying attosecond measurement and control techniques. Among their many potential applications, we focus on the exploration of the fundamental speed limit of electronic signal processing. This endeavour relies on ultimate-speed electron metrology, as provided by attosecond technology.

  11. Neutrino beams from electron capture at high gamma

    NASA Astrophysics Data System (ADS)

    Rolinec, Mark; Sato, Joe

    2007-08-01

    We investigate the potential of a flavor pure high gamma electron capture electron neutrino beam directed towards a large Water Cherenkov detector with 500 kt fiducial mass. The energy of the neutrinos is reconstructed by the position measurement within the detector and superb energy resolution capabilities could be achieved. We estimate the requirements for such a scenario to be competitive to a neutrino/anti-neutrino running at a neutrino factory with less accurate energy resolution. Although the requirements turn out to be extreme, in principle such a scenario could achieve as good abilities to resolve correlations and degeneracies in the search for sin2 2θ13 and δCP as a standard neutrino factory experiment.

  12. Single electron capture in fast ion-atom collisions

    NASA Astrophysics Data System (ADS)

    Milojević, Nenad

    2014-12-01

    Single-electron capture cross sections in collisions between fast bare projectiles and heliumlike atomic systems are investigated by means of the four-body boundary-corrected first Born (CB1-4B) approximation. The prior and post transition amplitudes for single charge exchange encompassing symmetric and asymmetric collisions are derived in terms of twodimensional real integrals in the case of the prior form and five-dimensional quadratures for the post form. The dielectronic interaction V12 = 1/r12 = 1/|r1 - r2| explicitly appears in the complete perturbation potential Vf of the post transition probability amplitude T+if. An illustrative computation is performed involving state-selective and total single capture cross sections for the p - He (prior and post form) and He2+, Li3+Be4+B5+C6+ - He (prior form) collisions at intermediate and high impact energies. We have also studied differential cross sections in prior and post form for single electron transfer from helium by protons. The role of dynamic correlations is examined as a function of increased projectile energy. Detailed comparisons with the measurements are carried out and the obtained theoretical cross sections are in reasonable agreement with the available experimental data.

  13. Electron-capture delayed fission in {sup 246}Es

    SciTech Connect

    Shaughnessy, D.A.; Gregorich, K.E.; Hendricks, M.B.; Lane, M.R.

    1997-12-31

    We have extended our systematic study of electron-capture delayed fission (ECDF) in neutron-deficient isotopes to {sup 246}Es. The {sup 246}Es was produced at the 88 Inch Cyclotron at Lawrence Berkeley National Laboratory via the {sup 249}Cf(p,xn){sup 250-x}Es reaction with 37 MeV protons. There were 19 {sup 249}Cf targets used simultaneously in our light ion multiple (LIM) target system. Alpha particles and fission fragments were detected in our rotating wheel system. In some experiments, TTA extractions were performed to remove interfering activities. The chemically separated samples were positioned between a solid-state particle detector and two x-rays detectors. This configuration enabled us to look for fissions in coincidence with K x-rays following electron-capture. Our measured production cross section of 13 {+-} 5 {mu}b for {sup 246}Es was much lower than the cross section predicted by a neutron evaporation code. The probability of delayed fission was determined from the number of x-ray/fission coincidences measured.

  14. Coherent pump pulses in Double Electron Electron Resonance spectroscopy.

    PubMed

    Tait, Claudia E; Stoll, Stefan

    2016-07-21

    The recent introduction of shaped pulses to Double Electron Electron Resonance (DEER) spectroscopy has led to significant enhancements in sensitivity through increased excitation bandwidths and improved control over spin dynamics. The application of DEER has so far relied on the presence of an incoherent pump channel to average out most undesired coherent effects of the pump pulse(s) on the observer spins. However, in fully coherent EPR spectrometers that are increasingly used to generate shaped pulses, the presence of coherent pump pulses means that these effects need to be explicitly considered. In this paper, we examine the effects of coherent rectangular and sech/tanh pump pulses in DEER experiments with up to three pump pulses. We show that, even in the absence of significant overlap of the observer and pump pulse excitation bandwidths, coherence transfer pathways involving both types of pulses generate spin echoes of considerable intensity. These echoes introduce artefacts, which, if not identified and removed, can easily lead to misinterpretation. We demonstrate that the observed echoes can be quantitatively modelled using a simple spin quantum dynamics approach that includes instrumental transfer functions. Based on an analysis of the echo crossing artefacts, we propose efficient phase cycling schemes for their suppression. This enables the use of advanced DEER experiments, characterized by high sensitivity and increased accuracy for long-distance measurements, on novel fully coherent EPR spectrometers. PMID:27339858

  15. Electronic and Magnetic Properties of Double Perovskites and Oxide Interfaces

    NASA Astrophysics Data System (ADS)

    Erten, Onur

    Transition metal oxides exhibit a wide range of fascinating phenomena ranging from high Tc superconductivity to colossal magnetoresistance. In this thesis, we examine the novel electronic and magnetic properties of double perovskites and oxide interfaces. First we focus on Sr2FeMoO6 which has a half-metallic ground state and a ferrimagnetic Tc=420 K, well above the room temperature. There are very few half-metals in nature and along with its high Tc, Sr2FeMoO6 has enormous potential in spintronics applications. We develop a minimal model that couples the conduction electrons on Mo (4d1) to the core spins of Fe (3d5). Delocalization of conduction electrons and maximizing the kinetic energy drives the long-range magnetic order. "Integrating out" the conduction electrons, we derive a new effective Hamiltonian, H eff, only for the localized spins. Heff is unique to double perovskites, and with its peculiar double square root form, it is different from standard Heisenberg or Anderson-Hasegawa Hamiltonians. Using Heff, we perform the first 3D, finite temperature calculations of double perovskites, going well beyond previous mean field or small cluster calculations. Next we consider Sr2CrOsO6 which has the highest Tc among all perovskites with a net moment. Its insulating behavior is puzzling given that Cr and Os are in the 3d3 and 5d3 configurations, half filled in t2g orbitals. The net moment at low temperature is M(0)=0.75 muB and non-monotonic magnetization as a function of temperature are quite unusual. To address these questions, we organize the problem through the hierarchy of its energy scales. To deal with the highest energy scale, the charge sector, we develop a multi-band Hubbard model that has different on-site Coulomb correlations on the Cr and Os sites. We solve this model using slave-rotor mean field theory which captures the essentials of the metal-Mott insulator transition and goes well beyond Hartree-Fock. We find a new criterion for the Mott transition

  16. Atomic electron excitation probabilities during orbital electron capture by the nucleus

    NASA Technical Reports Server (NTRS)

    Crasemann, B.; Chen, M. H.; Briand, J. P.; Chevallier, P.; Chetioui, A.; Tavernier, M.

    1979-01-01

    Approximate probabilities of electron excitation (shakeup/shakeoff) from various atomic states during nuclear ns electron capture have been calculated in the sudden approximation, using Hartree-Fock wave functions. Total excitation probabilities are much lower than during inner-shell ionization by photons or electrons, and ns states are more likely to be excited than np states. This latter result is borne out by K-alpha X-ray satellite spectra.

  17. Single-electron capture from hydrogenlike atomic systems

    NASA Astrophysics Data System (ADS)

    Samanta, R.; Jana, S.; Mandal, C. R.; Purkait, M.

    2012-03-01

    The total cross sections for single-charge transfer in H + H, He+ + H, He+ + He+, and Li2+ + H collisions have been calculated in the framework of four-body (4B) formalism of boundary corrected continuum intermediate state (BCCIS) approximation in the energy range 20-5000 keV/amu. The dynamic electron correlation is explicitly taken into account through the complete perturbation potentials. In the initial channel, the passive electron plays the role of screening of the projectile ion. However, continuum states of the target ion and the electron in the field of the residual projectile ion are included. In all cases, total single-electron capture cross sections have been calculated by summing over all contributions up to n = 2 shells and subshells, respectively, except the H-H collision. The present computed results, both in prior and post forms of BCCIS-4B method for symmetric and asymmetric cases have been compared with the available theoretical and experimental results. We found that our computed results, particularly in the prior form, are in better agreement with the experimental observations in comparison to other theoretical findings. Post-prior discrepancy has been found to be within 20% above 70 keV/amu for all interactions.

  18. Capturing Polyradical Protein Cations after an Electron Capture Event: Evidence for their Stable Distonic Structures in the Gas Phase

    NASA Astrophysics Data System (ADS)

    Baba, Takashi; Campbell, J. Larry

    2015-08-01

    We report on the formation and "capture" of polyradical protein cations after an electron capture event. Performed in a unique electron-capture dissociation (ECD) instrument, these experiments can generate reduced forms of multiply protonated proteins by sequential charge reduction using electrons with ~1 eV. The true structures of these possible polyradicals is considered: Do the introduced unpaired electrons recombine quickly to form a new two-electron bond, or do these unpaired electrons exist as radical sites with appropriate chemical reactivity? Using an established chemical probe—radical quenching with molecular oxygen—we demonstrate that these charge-reduced protein cations are indeed polyradicals that form adducts with up to three molecules of oxygen (i.e., tri-radical protein cations) that are stable for at least 100 ms.

  19. Detection of DNA double-strand breaks in boron neutron capture reaction.

    PubMed

    Okamoto, Emiko; Yamamoto, Tetsuya; Nakai, Kei; Fumiyo Yoshida; Matsumura, Akira

    2015-12-01

    We evaluated DNA double-strand breaks (DSBs) induced by boron neutron capture reaction (BNCR) using plasmid DNA, boron solution, and gel electrophoresis. The amount of the linear form of DNA produced by DSBs increased with the neutron-beam irradiation dose. The amount of the open-circular form of DNA produced by single-strand breaks (SSBs) increased with the neutron-beam irradiation dose and the (10)B concentration. The model facilitated quantification of BNCR-induced DSBs and SSBs, irrespective of the DNA repair mechanism. PMID:26302660

  20. Mutual neutralization in H+ - H- collisions by electron capture

    NASA Astrophysics Data System (ADS)

    Mančev, Ivan; Milojević, Nenad; Belkić, Dževad

    2013-07-01

    State-selective and total cross-sections for single-electron capture from H- by H+ covering the incident energy range from 10 to 3000 keV are computed by means of the four-body boundary corrected first Born (CB1-4B) approximation. A crucial connection between the Coulomb-distorted asymptotic state in the entrance channel and the pertinent perturbation, which causes the transition in the H+ - H- collisions, is consistently used in our computations of the “prior” version of cross-sections. The obtained results from the CB1-4B method clearly outperform the earlier findings by the close-coupling methods for the same problem. Comparisons with the available measurements are carried out and excellent agreement with the CB1 method is recorded down to impact energies as low as 10 keV.

  1. Picturing electron capture to the continuum in the transfer ionization of intermediate-energy He2+ collisions with argon

    NASA Astrophysics Data System (ADS)

    Zhang, R. T.; Ma, X.; Zhang, S. F.; Zhu, X. L.; Akula, Susmitha; Madison, D. H.; Li, B.; Qian, D. B.; Feng, W. T.; Guo, D. L.; Liu, H. P.; Yan, S. C.; Zhang, P. J.; Xu, S.; Chen, X. M.

    2013-01-01

    Electron emission occurring in transfer ionization for He2+ collisions with argon has been investigated using cold target recoil ion momentum spectroscopy. The double differential cross sections for electron capture to the continuum of the projectile (cusp-shaped electrons) are presented for collision energies from 17.5 to 75 keV/u. For an energy of 30 keV/u, we find a maximum in the experimental ratio of the cusp-shaped electron yield to the total electron yield. This result is explained in terms of the velocity matching between the projectile ion and the electron initially bound to the target. One of the important issues for double electron transitions is the role of electron-electron correlation. If this correlation is weak, then the transfer-ionization process can be viewed as two separate sequential processes. If this correlation is strong, then the transfer-ionization process would happen simultaneously and not sequentially. Our experimental and theoretical results indicate that correlation is weak and that the first step is target ionization followed by charge capture.

  2. Quantum electron-acoustic double layers in a magnetoplasma

    SciTech Connect

    Misra, A. P.; Samanta, S.

    2008-12-15

    Using a quantum magnetohydrodynamic (QMHD) model, the existence of small but finite amplitude quantum electron-acoustic double layers (QEADLs) is reported in a magnetized collisionless dense quantum plasma whose constituents are two distinct groups of cold and hot electrons, and the stationary ions forming only the neutralizing background. It is shown that the existence of steady state solutions of these double layers obtained from an extended Korteweg-de Vries (KdV) equation depends parametrically on the ratio of the cold to hot electron unperturbed number density ({delta}), the quantum diffraction parameter (H), the obliqueness parameter (l{sub z}), and the external magnetic field via the normalized electron-cyclotron frequency ({omega}). It is found that the system supports both compressive and rarefactive double layers depending on the parameters {delta} and l{sub z}. The effects of all these parameters on the profiles of the double layers are also examined numerically.

  3. Analysis of electron capture process in charge pumping sequence using time domain measurements

    SciTech Connect

    Hori, Masahiro Watanabe, Tokinobu; Ono, Yukinori; Tsuchiya, Toshiaki

    2014-12-29

    A method for analyzing the electron capture process in the charge pumping (CP) sequence is proposed and demonstrated. The method monitors the electron current in the CP sequence in time domain. This time-domain measurements enable us to directly access the process of the electron capture to the interface defects, which are obscured in the conventional CP method. Using the time-domain measurements, the rise time dependence of the capture process is systematically investigated. We formulate the capture process based on the rate equation and derive an analytic form of the current due to the electron capture to the defects. Based on the formula, the experimental data are analyzed and the capture cross section is obtained. In addition, the time-domain data unveil that the electron capture process completes before the electron channel opens, or below the threshold voltage in a low frequency range of the pulse.

  4. Theory and application of dissociative electron capture in molecular identification.

    PubMed

    Havey, Crystal D; Eberhart, Mark; Jones, Travis; Voorhees, Kent J; Laramée, James A; Cody, Robert B; Clougherty, Dennis P

    2006-04-01

    The coupling of an electron monochromator (EM) to a mass spectrometer (MS) has created a new analytical technique, EM-MS, for the investigation of electrophilic compounds. This method provides a powerful tool for molecular identification of compounds contained in complex matrices, such as environmental samples. In particular, EM-MS has been applied to the detection of nitrated aromatic compounds, many of which are potent mutagens and/or carcinogens and are considered environmental hazards. EM-MS expands the application and selectivity of traditional MS through the inclusion of a new dimension in the space of molecular characteristics-the electron resonance energy spectrum. EM-MS also enhances detection sensitivity as well because the entire electron flux of the proper energy can be delivered into the negative ion resonance that is analytically most useful to solving the problem at hand. However, before this tool can realize its full potential, it will be necessary to create a library of resonance energy scans from standards of the molecules for which EM-MS offers a practical means of detection. Unfortunately, the number of such standards is very large and not all of the compounds are commercially available, making this library difficult to construct. Here, an approach supplementing direct measurement with chemical inference and quantum scattering theory is presented to demonstrate the feasibility of directly calculating resonance energy spectra. This approach makes use of the symmetry of the transition-matrix element of the captured electron to discriminate between the spectra of isomers. As a way of validating this approach, the resonance values for 25 nitrated aromatic compounds were measured along with their relative abundance. Subsequently, the spectra for the isomers of nitrotoluene were shown to be consistent with the symmetry-based model. The initial success of this treatment suggests that it might be possible to predict negative ion resonances and thus

  5. Capturing reflected cladding modes from a fiber Bragg grating with a double-clad fiber coupler.

    PubMed

    Baiad, Mohamad Diaa; Gagné, Mathieu; Lemire-Renaud, Simon; De Montigny, Etienne; Madore, Wendy-Julie; Godbout, Nicolas; Boudoux, Caroline; Kashyap, Raman

    2013-03-25

    We present a novel measurement scheme using a double-clad fiber coupler (DCFC) and a fiber Bragg grating (FBG) to resolve cladding modes. Direct measurement of the optical spectra and power in the cladding modes is obtained through the use of a specially designed DCFC spliced to a highly reflective FBG written into slightly etched standard photosensitive single mode fiber to match the inner cladding diameter of the DCFC. The DCFC is made by tapering and fusing two double-clad fibers (DCF) together. The device is capable of capturing backward propagating low and high order cladding modes simply and efficiently. Also, we demonstrate the capability of such a device to measure the surrounding refractive index (SRI) with an extremely high sensitivity of 69.769 ± 0.035 μW/RIU and a resolution of 1.433 × 10(-5) ± 8 × 10(-9) RIU between 1.37 and 1.45 RIU. The device provides a large SRI operating range from 1.30 to 1.45 RIU with sufficient discrimination for all individual captured cladding modes. The proposed scheme can be adapted to many different types of bend, temperature, refractive index and other evanescent wave based sensors. PMID:23546069

  6. Two-dimensional Electronic Double-Quantum Coherence Spectroscopy

    PubMed Central

    Kim, Jeongho; Mukamel, Shaul

    2009-01-01

    CONSPECTUS The theory of electronic structure of many-electron systems like molecules is extraordinarily complicated. A lot can be learned by considering how electron density is distributed, on average, in the average field of the other electrons in the system. That is, mean field theory. However, to describe quantitatively chemical bonds, reactions, and spectroscopy requires consideration of the way that electrons avoid each other by the way they move; this is called electron correlation (or in physics, the many-body problem for fermions). While great progress has been made in theory, there is a need for incisive experimental tests that can be undertaken for large molecular systems in the condensed phase. Here we report a two-dimensional (2D) optical coherent spectroscopy that correlates the double excited electronic states to constituent single excited states. The technique, termed two-dimensional double-coherence spectroscopy (2D-DQCS), makes use of multiple, time-ordered ultrashort coherent optical pulses to create double- and single-quantum coherences over time intervals between the pulses. The resulting two-dimensional electronic spectrum maps the energy correlation between the first excited state and two-photon allowed double-quantum states. The principle of the experiment is that when the energy of the double-quantum state, viewed in simple models as a double HOMO to LUMO excitation, equals twice that of a single excitation, then no signal is radiated. However, electron-electron interactions—a combination of exchange interactions and electron correlation—in real systems generates a signal that reveals precisely how the energy of the double-quantum resonance differs from twice the single-quantum resonance. The energy shift measured in this experiment reveals how the second excitation is perturbed by both the presence of the first excitation and the way that the other electrons in the system have responded to the presence of that first excitation. We

  7. ELECTRON-CAPTURE SUPERNOVAE AS ORIGIN OF {sup 48}Ca

    SciTech Connect

    Wanajo, Shinya; Janka, Hans-Thomas; Mueller, Bernhard

    2013-04-20

    We report that electron-capture supernovae (ECSNe), arising from collapsing oxygen-neon-magnesium cores, are a possible source of {sup 48}Ca, whose origin has remained a longstanding puzzle. Our two-dimensional, self-consistent explosion model of an ECSN predicts ejection of neutron-rich matter with electron fractions Y{sub e} Almost-Equal-To 0.40-0.42 and relatively low entropies, s Almost-Equal-To 13-15 k{sub B} per nucleon (k{sub B} is the Boltzmann constant). Post-processing nucleosynthesis calculations result in appreciable production of {sup 48}Ca in such neutron-rich and low-entropy matter during the quasi-nuclear equilibrium and subsequent freezeout phases. The amount of ejected {sup 48}Ca can account for that in the solar inventory when we consider possible uncertainties in the entropies. ECSNe could thus be a site of {sup 48}Ca production in addition to a hypothetical, rare class of high-density Type Ia supernovae.

  8. Nonergodicity in Electron Capture Dissociation Investigated Using Hydrated Ion Nanocalorimetry

    PubMed Central

    Leib, Ryan D.; Donald, William A.; Bush, Matthew F.; O’Brien, Jeremy T.; Williams, Evan R.

    2007-01-01

    Hydrated divalent magnesium and calcium clusters are used as nanocalorimeters to measure the internal energy deposited into size-selected clusters upon capture of a thermally generated electron. The infrared radiation emitted from the cell and vacuum chamber surfaces as well as from the heated cathode results in some activation of these clusters, but this activation is minimal. No measurable excitation due to inelastic collisions occurs with the low-energy electrons used under these conditions. Two different dissociation pathways are observed for the divalent clusters that capture an electron: loss of water molecules (pathway I) and loss of a H atom and water molecules (pathway II). For Ca(H2O)n2+, pathway I occurs exclusively for n ≥ 30 whereas pathway II occurs exclusively for n ≤ 22 with a sharp transition in the branching ratio for these two processes that occurs for n ≈ 24. The number of water molecules lost by both pathways increases with increasing cluster size reaching a broad maximum between n = 23 and 32, and then decreases for larger clusters. From the number of water molecules that are lost from the reduced cluster, the average and maximum possible internal energy is determined to be ~4.4 and 5.2 eV, respectively, for Ca(H2O)302+. This value is approximately the same as the calculated ionization energies of M(H2O)n+, M = Mg and Ca, for large n indicating that the vast majority of the recombination energy is partitioned into internal modes of the ion and that the dissociation of these ions is statistical. For smaller clusters, estimates of the dissociation energies for the loss of H and of water molecules are obtained from theory. For Mg(H2O)n2+, n = 4 – 6, the average internal energy deposition is estimated to be 4.2 – 4.6 eV. The maximum possible energy deposited into the n = 5 cluster is < 7.1 eV, which is significantly less than the calculated recombination energy for this cluster. There does not appear to be a significant trend in the

  9. Double-neutron capture reaction and natural abundance of 183W, 195Pt and 199Hg isotopes

    NASA Astrophysics Data System (ADS)

    Karamian, S. A.; Aksenov, N. V.; Bozhikov, G. A.

    2016-06-01

    There are much data on neutron cross sections over the chart of nuclides for stable isotopes and not as much for the radioactive ones. Double neutron capture experiments could be fruitful to provide more data. Time-integrated mean flux of slow neutrons reaches the value of 2.3-1012 n/cm2 s at the irradiation port near the active zone of the IBR-2 pulsed reactor of JINR. This is enough to detect the double neutron capture products by the activation method. A high capture cross section is obtained in the present experiment for intermediate radioactive 182Ta and 194Ir target nuclides. Together with the known data for 198Au, these values may prove an essential role of double neutron capture process for nucleosynthesis of 183W, 195Pt and 199Hg isotopes at stellar conditions.

  10. Electron correlations in single-electron capture from helium by fast protons and α particles

    NASA Astrophysics Data System (ADS)

    Mančev, Ivan; Milojević, Nenad

    2010-02-01

    Single-electron capture from heliumlike atomic systems by bare projectiles is investigated by means of the four-body boundary-corrected first Born approximation (CB1-4B). The effect of the dynamic electron correlation is explicitly taken into account through the complete perturbation potential. The quantum-mechanical post and prior transition amplitudes for single charge exchange encompassing symmetric and/or asymmetric collisions are derived in terms of two-dimensional real integrals in the case of the prior form and five-dimensional quadratures for the post form. An illustrative computation is performed for single-electron capture from helium by protons and α particles at intermediate and high impact energies. The role of dynamic correlations is examined as a function of increased projectile energy. The validity and utility of the proposed CB1-4B method is critically assessed in comparison with the existing experimental data for total cross sections, and excellent agreement is obtained.

  11. Electron correlations in single-electron capture from helium by fast protons and {alpha} particles

    SciTech Connect

    Mancev, Ivan; Milojevic, Nenad

    2010-02-15

    Single-electron capture from heliumlike atomic systems by bare projectiles is investigated by means of the four-body boundary-corrected first Born approximation (CB1-4B). The effect of the dynamic electron correlation is explicitly taken into account through the complete perturbation potential. The quantum-mechanical post and prior transition amplitudes for single charge exchange encompassing symmetric and/or asymmetric collisions are derived in terms of two-dimensional real integrals in the case of the prior form and five-dimensional quadratures for the post form. An illustrative computation is performed for single-electron capture from helium by protons and {alpha} particles at intermediate and high impact energies. The role of dynamic correlations is examined as a function of increased projectile energy. The validity and utility of the proposed CB1-4B method is critically assessed in comparison with the existing experimental data for total cross sections, and excellent agreement is obtained.

  12. Capturing relic neutrinos with {beta}- and double {beta}-decaying nuclei

    SciTech Connect

    Hodak, Rastislav; Kovalenko, Sergey; Simkovic, Fedor

    2009-11-09

    Neutrinos are probably one of the most important structural constituents of the Universe. The Big Bang Theory predicts that the significant component of them is formed by the cosmic neutrino background, an analogues of the big bang relic photons comprising the cosmic microwave background radiation, which has been measured with amazing accuracy. Properties of the relic neutrino background are closely related to the ones of the cosmic microwave radiation. Relic neutrinos pervade space, but their temperature is extremely small, being of the order of 0.1 meV. Although belonging to the most abundant particles of the Universe, the relic neutrinos evade direct detection so far. This is because the low-energy neutrinos interact only very weakly with matter. In this contribution, we explore the feasibility to detect the cosmic neutrino background by means of {beta}-decaying ({sup 3}H and {sup 187}Re) and double beta decaying ({sup 100}Mo) nuclei. In addition, we address the question whether double relic neutrino capture on nuclei can be an obstacle for observation of neutrinoless double {beta}-decay.

  13. Spin-resolved state-selective electron capture in C5+-H collisions

    NASA Astrophysics Data System (ADS)

    Liu, C. H.; Wang, J. G.; Janev, R. K.

    2016-09-01

    The electron capture processes in the C5+(1s)+H(1s) collision system are investigated by the quantum-mechanical molecular orbital close-coupling (QMOCC) method in the energy range of 10‑5–10 keV u‑1. Accurate molecular structure calculations are performed by the ab initio multireference single- and double-excitation configuration interaction method. The electron translational effects are included in the calculations. The total and spin-resolved state-selective cross sections are presented and compared with the available experimental and theoretical data. The present results have a good agreement with the experimental measurements. Our calculations show that the electron translation factors play a very important role for energies above 0.1 keV u‑1 leading to significant differences between the present and the previous QMOOC cross section results of Nolte et al 2012 (J. Phys. B: At. Mol. Opt. Phys. 45 245202). The effects of the core electron also cannot be ignored below 2 keV u‑1. Model potential calculations, in which the core electron is treated as frozen, cannot give accurate spin-resolved cross sections.

  14. Double relativistic electron-accelerating mirror

    SciTech Connect

    Andreev, Aleksandr A; Platonov, Konstantin Yu

    2013-05-31

    A numerical simulation of the interaction of a laser pulse with ultrathin targets has revealed a possibility of generating thin dense relativistic electron layers. The maximum kinetic energy of the electron mirror can be gained using an optimal combination of the target thickness and the laser pulse intensity and duration. It is proposed to use an additional (second) laser target, located at an optimal distance from the first target to cut off the laser pulse from the electron layer when the latter gains a maximum kinetic energy. This relativistic electron mirror can be used for efficient generation of 'hard' coherent radiation via counter reflection of an additional (probe) laser pulse from the mirror. (interaction of laser radiation with matter. laser plasma)

  15. Low-Energy Electron Capture in Collisions of C3+ with He

    SciTech Connect

    Wu, Y.; Qi, Y. Y.; Yan, J.; Wang, J. G.; Li, Y.; Buenker, R. J.; Kato, D.; Krstic, Predrag S

    2009-01-01

    Charge transfer processes due to collisions of ground-state C{sup 3+}(1s{sup 2}2s {sup 2}S) ions with He atoms are studied using the quantum-mechanical molecular-orbital close-coupling method for energies in the range 10{sup -4}-2 x 10{sup 3} eV/u. The ab initio adiabatic potentials and radial couplings utilized in the calculations are obtained from the multireference single- and double-excitation configuration interaction approach. Total and state-selective single-electron capture cross sections and rate coefficients are calculated and compared with the available experimental and theoretical data. A good agreement is found between the measured cross sections and the present calculations. However, the previous calculations of total rate coefficients using the Landau-Zener model are one to two orders of magnitude smaller than the present results.

  16. Nucleosynthesis in Electron Capture Supernovae of Asymptotic Giant Branch Stars

    NASA Astrophysics Data System (ADS)

    Wanajo, S.; Nomoto, K.; Janka, H.-T.; Kitaura, F. S.; Müller, B.

    2009-04-01

    We examine nucleosynthesis in the electron capture supernovae of progenitor asymptotic giant branch stars with an O-Ne-Mg core (with the initial stellar mass of 8.8 M sun). Thermodynamic trajectories for the first 810 ms after core bounce are taken from a recent state-of-the-art hydrodynamic simulation. The presented nucleosynthesis results are characterized by a number of distinct features that are not shared with those of other supernovae from the collapse of stars with iron core (with initial stellar masses of more than 10 M sun). First is the small amount of 56Ni (0.002-0.004 M sun) in the ejecta, which can be an explanation for the observed properties of faint supernovae such as SNe 2008S and 1997D. In addition, the large Ni/Fe ratio is in reasonable agreement with the spectroscopic result of the Crab nebula (the relic of SN 1054). Second is the large production of 64Zn, 70Ge, light p-nuclei (74Se, 78Kr, 84Sr, and 92Mo), and in particular, 90Zr, which originates from the low Ye (0.46-0.49, the number of electrons per nucleon) ejecta. We find, however, that only a 1%-2% increase of the minimum Ye moderates the overproduction of 90Zr. In contrast, the production of 64Zn is fairly robust against a small variation of Ye . This provides the upper limit of the occurrence of this type of events to be about 30% of all core-collapse supernovae.

  17. ELECTRON-CAPTURE SUPERNOVAE AS SOURCES OF {sup 60}Fe

    SciTech Connect

    Wanajo, Shinya; Janka, Hans-Thomas; Mueller, Bernhard

    2013-09-01

    We investigate the nucleosynthesis of the radionuclide {sup 60}Fe in electron-capture supernovae (ECSNe). The nucleosynthetic results are based on a self-consistent, two-dimensional simulation of an ECSN as well as models in which the densities are systematically increased by some factors (low-entropy models). {sup 60}Fe is found to be appreciably made in neutron-rich ejecta during the nuclear quasi-equilibrium phase with greater amounts being produced in the lower-entropy models. Our results, combining them with the yields of core-collapse supernovae in the literature, suggest that ECSNe account for at least 4%-30% of live {sup 60}Fe in the Milky Way. ECSNe co-produce neutron-rich isotopes, {sup 48}Ca, {sup 50}Ti, {sup 54}Cr, some light trans-iron elements, and possibly weak r-process elements including some radionuclides such as {sup 93}Zr, {sup 99}Tc, and {sup 107}Pd, whose association with {sup 60}Fe might have been imprinted in primitive meteorites or in the deep ocean crust on the Earth.

  18. Electron-capture Supernovae as Sources of 60Fe

    NASA Astrophysics Data System (ADS)

    Wanajo, Shinya; Janka, Hans-Thomas; Müller, Bernhard

    2013-09-01

    We investigate the nucleosynthesis of the radionuclide 60Fe in electron-capture supernovae (ECSNe). The nucleosynthetic results are based on a self-consistent, two-dimensional simulation of an ECSN as well as models in which the densities are systematically increased by some factors (low-entropy models). 60Fe is found to be appreciably made in neutron-rich ejecta during the nuclear quasi-equilibrium phase with greater amounts being produced in the lower-entropy models. Our results, combining them with the yields of core-collapse supernovae in the literature, suggest that ECSNe account for at least 4%-30% of live 60Fe in the Milky Way. ECSNe co-produce neutron-rich isotopes, 48Ca, 50Ti, 54Cr, some light trans-iron elements, and possibly weak r-process elements including some radionuclides such as 93Zr, 99Tc, and 107Pd, whose association with 60Fe might have been imprinted in primitive meteorites or in the deep ocean crust on the Earth.

  19. A new analytical formula for neutron capture gamma dose calculations in double-bend mazes in radiation therapy

    PubMed Central

    Ghiasi, Hosein; Mesbahi, Asghar

    2012-01-01

    Background Photoneutrons are produced in radiation therapy with high energy photons. Also, capture gamma rays are the byproduct of neutrons interactions with wall material of radiotherapy rooms. Aim In the current study an analytical formula was proposed for capture gamma dose calculations in double bend mazes in radiation therapy rooms. Materials and methods A total of 40 different layouts with double-bend mazes and a 18 MeV photon beam of Varian 2100 Clinac were simulated using MCNPX Monte Carlo (MC) code. Neutron capture gamma ray dose equivalent was calculated by the MC method along the maze and at the maze entrance door of all the simulated rooms. Then, all MC resulted data were fitted to an empirical formula for capture gamma dose calculations. Wu–McGinley analytical formula for capture gamma dose equivalent at the maze entrance door in single-bend mazes was also used for comparison purposes. Results For capture gamma dose equivalents at the maze entrance door, the difference of 2–11% was seen between MC and the derived equation, while the difference of 36–87% was found between MC and the Wu–McGinley methods. Conclusion Our results showed that the derived formula results were consistent with the MC results for all of 40 different geometries. However, as a new formula, further evaluations are required to validate its use in practical situations. Finally, its application is recommend for capture gamma dose calculations in double-bend mazes to improve shielding calculations. PMID:24377027

  20. 77 FR 11588 - Certain Electronic Devices for Capturing and Transmitting Images, and Components Thereof

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-27

    ... COMMISSION Certain Electronic Devices for Capturing and Transmitting Images, and Components Thereof AGENCY: U... capturing and transmitting images and components thereof by reason of infringement of certain claims of U.S... capturing and transmitting images and components thereof by reason of infringement of one or more of...

  1. Muon capture on light isotopes measured with the Double Chooz detector

    NASA Astrophysics Data System (ADS)

    Abe, Y.; Abrahão, T.; Almazan, H.; Alt, C.; Appel, S.; Barriere, J. C.; Baussan, E.; Bekman, I.; Bergevin, M.; Bezerra, T. J. C.; Bezrukov, L.; Blucher, E.; Brugière, T.; Buck, C.; Busenitz, J.; Cabrera, A.; Camilleri, L.; Carr, R.; Cerrada, M.; Chauveau, E.; Chimenti, P.; Collin, A. P.; Conover, E.; Conrad, J. M.; Crespo-Anadón, J. I.; Crum, K.; Cucoanes, A. S.; Damon, E.; Dawson, J. V.; de Kerret, H.; Dhooghe, J.; Dietrich, D.; Djurcic, Z.; dos Anjos, J. C.; Dracos, M.; Etenko, A.; Fallot, M.; Felde, J.; Fernandes, S. M.; Fischer, V.; Franco, D.; Franke, M.; Furuta, H.; Gil-Botella, I.; Giot, L.; Göger-Neff, M.; Gomez, H.; Gonzalez, L. F. G.; Goodenough, L.; Goodman, M. C.; Haag, N.; Hara, T.; Haser, J.; Hellwig, D.; Hofmann, M.; Horton-Smith, G. A.; Hourlier, A.; Ishitsuka, M.; Jochum, J.; Jollet, C.; Kaether, F.; Kalousis, L. N.; Kamyshkov, Y.; Kaneda, M.; Kaplan, D. M.; Kawasaki, T.; Kemp, E.; Kryn, D.; Kuze, M.; Lachenmaier, T.; Lane, C. E.; Lasserre, T.; Letourneau, A.; Lhuillier, D.; Lima, H. P.; Lindner, M.; López-Castaño, J. M.; LoSecco, J. M.; Lubsandorzhiev, B.; Lucht, S.; Maeda, J.; Mariani, C.; Maricic, J.; Martino, J.; Matsubara, T.; Mention, G.; Meregaglia, A.; Miletic, T.; Milincic, R.; Minotti, A.; Nagasaka, Y.; Navas-Nicolás, D.; Novella, P.; Oberauer, L.; Obolensky, M.; Onillon, A.; Osborn, A.; Palomares, C.; Pepe, I. M.; Perasso, S.; Porta, A.; Pronost, G.; Reichenbacher, J.; Reinhold, B.; Röhling, M.; Roncin, R.; Rybolt, B.; Sakamoto, Y.; Santorelli, R.; Schilithz, A. C.; Schönert, S.; Schoppmann, S.; Shaevitz, M. H.; Sharankova, R.; Shrestha, D.; Sibille, V.; Sinev, V.; Skorokhvatov, M.; Smith, E.; Soiron, M.; Spitz, J.; Stahl, A.; Stancu, I.; Stokes, L. F. F.; Strait, M.; Suekane, F.; Sukhotin, S.; Sumiyoshi, T.; Sun, Y.; Svoboda, R.; Terao, K.; Tonazzo, A.; Trinh Thi, H. H.; Valdiviesso, G.; Vassilopoulos, N.; Veyssiere, C.; Vivier, M.; von Feilitzsch, F.; Wagner, S.; Walsh, N.; Watanabe, H.; Wiebusch, C.; Wurm, M.; Yang, G.; Yermia, F.; Zimmer, V.; Double Chooz Collaboration

    2016-05-01

    Using the Double Chooz detector, designed to measure the neutrino mixing angle θ13, the products of μ- capture on 12C,13C,14N, and 16O have been measured. Over a period of 489.5 days, 2.3 ×106 stopping cosmic μ- have been collected, of which 1.8 ×105 captured on carbon, nitrogen, or oxygen nuclei in the inner detector scintillator or acrylic vessels. The resulting isotopes were tagged using prompt neutron emission (when applicable), the subsequent β decays, and, in some cases, β -delayed neutrons. The most precise measurement of the rate of 12C(μ-,ν ) 12B to date is reported: 6 .57-0.21+0.11×103s-1 , or (17 .35-0.59+0.35)% of nuclear captures. By tagging excited states emitting γ s , the ground state transition rate to 12B has been determined to be 5 .68-0.23+0.14 ×103s-1 . The heretofore unobserved reactions 12C(μ-,ν α ) 8Li,13C(μ-,ν n α ) 8Li , and 13C(μ-,ν n ) 12B are measured. Further, a population of β n decays following stopping muons is identified with 5.5 σ significance. Statistics limit our ability to identify these decays definitively. Assuming negligible production of 8He, the reaction 13C(μ-,ν α ) 9Li is found to be present at the 2.7 σ level. Limits are set on a variety of other processes.

  2. High-resolution error detection in the capture process of a single-electron pump

    NASA Astrophysics Data System (ADS)

    Giblin, S. P.; See, P.; Petrie, A.; Janssen, T. J. B. M.; Farrer, I.; Griffiths, J. P.; Jones, G. A. C.; Ritchie, D. A.; Kataoka, M.

    2016-01-01

    The dynamic capture of electrons in a semiconductor quantum dot (QD) by raising a potential barrier is a crucial stage in metrological quantized charge pumping. In this work, we use a quantum point contact (QPC) charge sensor to study errors in the electron capture process of a QD formed in a GaAs heterostructure. Using a two-step measurement protocol to compensate for 1/f noise in the QPC current, and repeating the protocol more than 106 times, we are able to resolve errors with probabilities of order 10 - 6 . For the studied sample, one-electron capture is affected by errors in ˜ 30 out of every million cycles, while two-electron capture was performed more than 106 times with only one error. For errors in one-electron capture, we detect both failure to capture an electron and capture of two electrons. Electron counting measurements are a valuable tool for investigating non-equilibrium charge capture dynamics, and necessary for validating the metrological accuracy of semiconductor electron pumps.

  3. Quantifying Data Quality for Clinical Trials Using Electronic Data Capture

    PubMed Central

    Nahm, Meredith L.; Pieper, Carl F.; Cunningham, Maureen M.

    2008-01-01

    Background Historically, only partial assessments of data quality have been performed in clinical trials, for which the most common method of measuring database error rates has been to compare the case report form (CRF) to database entries and count discrepancies. Importantly, errors arising from medical record abstraction and transcription are rarely evaluated as part of such quality assessments. Electronic Data Capture (EDC) technology has had a further impact, as paper CRFs typically leveraged for quality measurement are not used in EDC processes. Methods and Principal Findings The National Institute on Drug Abuse Treatment Clinical Trials Network has developed, implemented, and evaluated methodology for holistically assessing data quality on EDC trials. We characterize the average source-to-database error rate (14.3 errors per 10,000 fields) for the first year of use of the new evaluation method. This error rate was significantly lower than the average of published error rates for source-to-database audits, and was similar to CRF-to-database error rates reported in the published literature. We attribute this largely to an absence of medical record abstraction on the trials we examined, and to an outpatient setting characterized by less acute patient conditions. Conclusions Historically, medical record abstraction is the most significant source of error by an order of magnitude, and should be measured and managed during the course of clinical trials. Source-to-database error rates are highly dependent on the amount of structured data collection in the clinical setting and on the complexity of the medical record, dependencies that should be considered when developing data quality benchmarks. PMID:18725958

  4. COMPARATIVE ANALYSIS OF DIOXINS AND FURANS BY HIGH RESOLUTION AND ELECTRON CAPTURE MASS SPECTROMETRY

    EPA Science Inventory

    Known mixtures and unknown atmospheric sample extracts containing polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/P) were analyzed by both electron impact, high resolution, mass spectrometry (HRMS) and by electron capture, negative ion, low resolution ma...

  5. Coincidence measurements of electron capture and loss in ion-atom collisions

    SciTech Connect

    DuBois, R.D.

    1990-09-01

    Collisions between fast, fully stripped projectiles and atomic targets predominantly result in target electrons being ejected to the continuum. For fast partially stripped projectiles which bring weakly bound electrons into the collision, projectile ionization can also contribute to the observed electron spectra. At lower impact velocities, electron capture by the projectile ion becomes important and higher order processes, often referred to as transfer ionization, can be a significant source of free electrons. In recent years, coincidence techniques have been used to evaluate the relative importance of electron capture and loss in free electron production, to separate the capture and loss contributions from those resulting from target ionization alone, and to provide more detailed information about electron capture and loss mechanisms than is available from total cross section measurements. A brief survey of these experiments will be presented. 23 refs., 9 figs.

  6. MAGNETIC FIELD-DECAY-INDUCED ELECTRON CAPTURES: A STRONG HEAT SOURCE IN MAGNETAR CRUSTS

    SciTech Connect

    Cooper, Randall L.; Kaplan, David L. E-mail: dkaplan@kitp.ucsb.edu

    2010-01-10

    We propose a new heating mechanism in magnetar crusts. Magnetars' crustal magnetic fields are much stronger than their surface fields; therefore, magnetic pressure partially supports the crust against gravity. The crust loses magnetic pressure support as the field decays and must compensate by increasing the electron degeneracy pressure; the accompanying increase in the electron Fermi energy induces nonequilibrium, exothermic electron captures. The total heat released via field-decay electron captures is comparable to the total magnetic energy in the crust. Thus, field-decay electron captures are an important, if not the primary, mechanism powering magnetars' soft X-ray emission.

  7. SUPPRESSION OF ENERGETIC ELECTRON TRANSPORT IN FLARES BY DOUBLE LAYERS

    SciTech Connect

    Li, T. C.; Drake, J. F.; Swisdak, M.

    2012-09-20

    During flares and coronal mass ejections, energetic electrons from coronal sources typically have very long lifetimes compared to the transit times across the systems, suggesting confinement in the source region. Particle-in-cell simulations are carried out to explore the mechanisms of energetic electron transport from the corona to the chromosphere and possible confinement. We set up an initial system of pre-accelerated hot electrons in contact with ambient cold electrons along the local magnetic field and let it evolve over time. Suppression of transport by a nonlinear, highly localized electrostatic electric field (in the form of a double layer) is observed after a short phase of free-streaming by hot electrons. The double layer (DL) emerges at the contact of the two electron populations. It is driven by an ion-electron streaming instability due to the drift of the back-streaming return current electrons interacting with the ions. The DL grows over time and supports a significant drop in temperature and hence reduces heat flux between the two regions that is sustained for the duration of the simulation. This study shows that transport suppression begins when the energetic electrons start to propagate away from a coronal acceleration site. It also implies confinement of energetic electrons with kinetic energies less than the electrostatic energy of the DL for the DL lifetime, which is much longer than the electron transit time through the source region.

  8. Ionization and electron-capture cross sections for single- and multiple-electron removal from H2O by Li3 + impact

    NASA Astrophysics Data System (ADS)

    Luna, H.; Wolff, W.; Montenegro, E. C.; Tavares, André C.; Lüdde, H. J.; Schenk, G.; Horbatsch, M.; Kirchner, T.

    2016-05-01

    In this work, we report experimental and theoretical ionization and electron-capture cross sections for single-, double- and triple-electron removal from H2O by Li3 + impact at energies ranging from 0.75 to 5.8 MeV. The experiment was carried out by selecting both the final charge state of the projectile and the ejected fragments in coincidence to obtain cross sections associated with ionization and electron-capture channels. The ionic fragments and the emitted electrons produced under single-collision conditions were collected by a time-of-flight spectrometer with single-hit (e.g., OH++H0 ) and double-hit events (e.g., OH++H+ ) properly discriminated. For the one- and two-electron removal cases, the calculations based on the basis generator method for orbital propagation agree well with the experiment for most of the collision channels studied. Auger-electron emission after vacancy production in the inner 2 a1 orbital of H2O is shown to have a substantial effect on the final charge-state distributions over the entire impact-energy interval.

  9. A New Mass Criterium for Electron Capture Supernovae

    NASA Astrophysics Data System (ADS)

    Poelarends, Arend

    2016-06-01

    Electron capture supernovae (ECSN) are thought to populate the mass range between massive white dwarf progenitors and core collapse supernovae. It is generally believed that the initial stellar mass range for ECSN from single stars is about 0.5-1.0 M⊙ wide and centered around a value of 8.5 or 9 M⊙, depending on the specifics of the physics of convection and mass loss one applies. Since mass loss in a binary system is able to delay or cancel the second dredge-up, it is also believed that the initial mass range for ECSN in binary systems is wider than in single stars, but an initial mass range has not been defined yet.The last phase of stars in this particular mass range, however, is challenging to compute, either due to recurring Helium shell flashes, or due to convectively bound flames in the degenerate interior of the star. It would be helpful, nevertheless, to know before we enter these computationally intensive phases whether a star will explode as an ECSN or not. The mass of the helium core after helium core burning is one such criterium (Nomoto, 1984), which predicts that ECSN will occur if the helium core mass is between 2.0 M⊙ and 2.5 M⊙. However, since helium cores can be subject to erosion due to mass loss — even during helium core burning, this criterium will not yield accurate predictions for stars in binary systems.We present a dense grid of stellar evolution models that allow us to put constraints on the final fate of their cores, based on a combination of Carbon/Oxygen core mass, the mass of the surrounding Helium layer and C/O abundance. We find that CO cores with masses between 1.365 and 1.420 M⊙ at the end of Carbon burning will result in ECSN, with some minor adjustments of these ranges due to the mass of the Helium layer and the C/O ratio. While detailed models of stars within the ECSN mass range remain necessary to understand the details of pre-ECSN evolution, our research refines the Helium core criterion and provides a useful way

  10. Double-walled carbon nanocones: stability and electronic structure

    NASA Astrophysics Data System (ADS)

    Brito, Elias; Freitas, Aliliane; Silva, Thiago; Guerra, Thiago; Azevedo, Sergio

    2015-06-01

    We have applied first-principles calculations, based on the density functional theory, to investigate the stability and electronic properties of double-walled carbon nanocones, 60°60°, 120°120° and 60°120° with different rotation angles between the walls. We have shown that the most favorable double-walled nanocone studied here is that of angles of 60°60°, with rotation angle of 36° and distance between apexes of 4.22 Å. We have found that, the interaction between the walls of rotated double-walled nanocones introduce geometric distortion in gap states, such as in Fermi level. These results should have consequences on the field emission properties of double-walled carbon nanocones. Additionally, we also investigated the spin polarization of such structures, and we have found unpaired electrons, which induces a total spin from 1 and 1/2 for 60°60° and 60°120° double cones, respectively.

  11. Absolute differential cross sections for electron capture and loss by kilo-electron-volt hydrogen atoms

    NASA Technical Reports Server (NTRS)

    Smith, G. J.; Johnson, L. K.; Gao, R. S.; Smith, K. A.; Stebbings, R. F.

    1991-01-01

    This paper reports measurements of absolute differential cross sections for electron capture and loss for fast hydrogen atoms incident on H2, N2, O2, Ar, and He. Cross sections have been determined in the 2.0- to 5.0-keV energy range over the laboratory angular range 0.02-2 deg, with an angular, resolution of 0.02 deg. The high angular resolution allows observation of the structure at small angles in some of the cross sections. Comparison of the present results with those of other authors generally shows very good agreement.

  12. Thermodynamic analysis of the double Brayton cycle with the use of oxy combustion and capture of CO2

    NASA Astrophysics Data System (ADS)

    Ziółkowski, Paweł; Zakrzewski, Witold; Kaczmarczyk, Oktawia; Badur, Janusz

    2013-06-01

    In this paper, thermodynamic analysis of a proposed innovative double Brayton cycle with the use of oxy combustion and capture of CO2, is presented. For that purpose, the computation flow mechanics (CFM) approach has been developed. The double Brayton cycle (DBC) consists of primary Brayton and secondary inverse Brayton cycle. Inversion means that the role of the compressor and the gas turbine is changed and firstly we have expansion before compression. Additionally, the workingfluid in the DBC with the use of oxy combustion and CO2 capture contains a great amount of H2O and CO2, and the condensation process of steam (H2O) overlaps in negative pressure conditions. The analysis has been done for variants values of the compression ratio, which determines the lowest pressure in the double Brayton cycle.

  13. Towards a fast calculator for the radiation characteristics of radiative recombination and radiative electron capture

    NASA Astrophysics Data System (ADS)

    Weber, G.; Ding, H.; Herdrich, M. O.; Surzhykov, A.

    2015-04-01

    The radiative capture of free electrons (radiative recombination) and bound electrons (radiative electron capture) are among the most important charge changing processes for fast, highly-charged ions. While total cross sections can be obtained by an approximate formula with reasonable accuracy, the estimation of angular distributions and polarization properties of the emitted radiation requires a fully relativistic treatment that is numerical expensive. Therefore we recently started the development of a fast calculator for these radiation characteristics. The program is based on a grid of rigorously calculated data points for free- electron capture into bare ions, between which interpolation is performed to obtain radiation characteristics for specific collision systems. Also capture into few-electron systems is taken into account in an approximate way. We present first results from this development.

  14. Conformation dependent electronic transport in a DNA double-helix

    SciTech Connect

    Kundu, Sourav Karmakar, S. N.

    2015-10-15

    We present a tight-binding study of conformation dependent electronic transport properties of DNA double-helix including its helical symmetry. We have studied the changes in the localization properties of DNA as we alter the number of stacked bases within every pitch of the double-helix keeping fixed the total number of nitrogen bases within the DNA molecule. We take three DNA sequences, two of them are periodic and one is random and observe that in all the cases localization length increases as we increase the radius of DNA double-helix i.e., number of nucleobases within a pitch. We have also investigated the effect of backbone energetic on the I-V response of the system and found that in presence of helical symmetry, depending on the interplay of conformal variation and disorder, DNA can be found in either metallic, semiconducting and insulating phases, as observed experimentally.

  15. A Benign, Low Z Electron Capture Agent for Negative Ion TPCs

    NASA Technical Reports Server (NTRS)

    Martoff, C. J.; Dion, M. P.; Hosack, M.; Barton, D.; Black, J. K.

    2008-01-01

    We have identified nitromethane (CH3NO2) as an effective electron capture agent for negative ion TPCs (NITPCs). We present drift velocity and longitudinal diffusion measurements for negative ion gas mixtures using nitromethane as the capture agent. Not only is nitromethane substantially more benign than the only other identified capture agent, CS2, but its low atomic number will enable the use of the NITPC as a photoelectric X-ray polarimeter in the 1-10 keV band.

  16. Effects of hot electron inertia on electron-acoustic solitons and double layers

    SciTech Connect

    Verheest, Frank; Hellberg, Manfred A.

    2015-07-15

    The propagation of arbitrary amplitude electron-acoustic solitons and double layers is investigated in a plasma containing cold positive ions, cool adiabatic and hot isothermal electrons, with the retention of full inertial effects for all species. For analytical tractability, the resulting Sagdeev pseudopotential is expressed in terms of the hot electron density, rather than the electrostatic potential. The existence domains for Mach numbers and hot electron densities clearly show that both rarefactive and compressive solitons can exist. Soliton limitations come from the cool electron sonic point, followed by the hot electron sonic point, until a range of rarefactive double layers occurs. Increasing the relative cool electron density further yields a switch to compressive double layers, which ends when the model assumptions break down. These qualitative results are but little influenced by variations in compositional parameters. A comparison with a Boltzmann distribution for the hot electrons shows that only the cool electron sonic point limit remains, giving higher maximum Mach numbers but similar densities, and a restricted range in relative hot electron density before the model assumptions are exceeded. The Boltzmann distribution can reproduce neither the double layer solutions nor the switch in rarefactive/compressive character or negative/positive polarity.

  17. GEANT4 simulations for in trap decay spectroscopy for electron capture branching ratio measurements using the TITAN facility

    NASA Astrophysics Data System (ADS)

    Seeraji, Shakil; Andreoiu, C.; Jang, F.; Ma, T.; Chaudhuri, A.; Grossheim, A.; Kwiatkowski, A. A.; Schultz, B. E.; Mane, E.; Gwinner, G.; Dilling, J.; Lennarz, A.; Frekers, D.; Chowdhury, U.; Simon, V. V.; Brunner, T.; Delheij, P.; Simon, M. C.

    2012-10-01

    The TITAN-EC project has developed a unique technique to measure electron capture branching ratios (ECBRs) of short lived intermediate nuclide involved in double beta decay. The ECBR information is important for determination of nuclear matrix elements of double-β decay for both double beta decay (2νββ) and neutrino-less double beta decay (0νββ) processes. An important feature of this technique is the use of open access penning trap. Radioactive ions are stored in the trap and their decays are observed. Electrons produced from β decay are guided out of the trap by the Penning trap's strong magnetic field and the x-ray from EC are detected by seven Si(Li) detectors placed radially around trap using thin Be windows. This set-up provides a lower background for the x-ray detection compared to earlier ECBC measurements where the beam is implanted in mylar tape. Detailed GEANT4 simulations have been performed to characterize the efficiency of the detectors and understand their response. In addition the impact of different sizes and shapes of the ion cloud inside the trap has also been investigated to optimize the experimental set-up.

  18. 77 FR 4059 - Certain Electronic Devices for Capturing and Transmitting Images, and Components Thereof; Receipt...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-26

    ... COMMISSION Certain Electronic Devices for Capturing and Transmitting Images, and Components Thereof; Receipt... Images, and Components Thereof, DN 2869; the Commission is soliciting comments on any public interest... for capturing and transmitting images, and components thereof. The complaint names Apple Inc....

  19. Double deflection system for an electron beam device

    DOEpatents

    Parker, Norman W.; Golladay, Steven D.; Crewe, Albert V.

    1978-01-01

    A double deflection scanning system for electron beam instruments is provided embodying a means of correcting isotropic coma, and anisotropic coma aberrations induced by the magnetic lens of such an instrument. The scanning system deflects the beam prior to entry into the magnetic lens from the normal on-axis intersection of the beam with the lens according to predetermined formulas and thereby reduces the aberrations.

  20. Solving the Neutrino Mass Mystery using Double Beta Decay. An Examination of the Feasibility of Xennoon Purification and Ion Capture and Release using an Electrostatic Probe

    SciTech Connect

    Outschoorn, Verena M

    2003-09-05

    Double beta decay has long been recognized as a useful avenue for the study of electron neutrinos, especially the neutrino mass and its fundamental nature (Majorana or Dirac). Recent neutrino oscillation experiments have provided compelling evidence that the neutrino has mass. The detection of the neutrinoless mode of double beta decay would finally set a lower limit on the mass of the electron neutrino, as well as prove that the neutrino is a Majorana particle (with opposite spin, it is its own anti-particle). The Enriched Xenon Observatory (EXO) project attempts to detect neutrinoless double beta decay using {sup 136}Xe that decays by this process to {sup 136}Ba{sup 2} + e{sup -} + e{sup -}. Perhaps one of the most significant characteristics of this project is the reduction of the background through the identification of the Barium ions for each individual event using laser fluorescence techniques. This project also proposes to collect scintillation light in addition to the ionization electrons in order to further improve energy resolution. Current work at SLAC includes the development of a purification system for xenon, as well as tests for the capture and release of single ions using an electrostatic probe.

  1. Observation of Energy-Dependent Electron-Capture Decay in Secondary Galactic Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Niebur, S. M.; Binns, W. R.; Hink, P. L.; Israel, M. H.; Klarmann, J.; Lijowski, M.; Christian, E. R.; von Rosenvinge, T. T.; Cummings, A. C.; George, J. S.; Leske, R. A.; Mewaldt, R. A.; Stone, E. C.; Wiedenbeck, M. E.; Yanasak, N. E.

    2000-04-01

    Secondary galactic cosmic rays are produced at cosmic ray energies by fragmentation of primary cosmic rays during propagation through the interstellar medium; these nuclei carry a signature of the energy at which they were produced. Although electron-capture decay is inhibited at most of the energies typical of cosmic rays, decay is possible at the lower energies for isotopes such as 51Cr and 49V. We have analyzed Titanium, Vanadium, and Chromium isotopic data from the Cosmic Ray Isotope Spectrometer on ACE and found evidence of electron-capture decay at lower energies. We will present a comparison of secondary electron-capture decay isotope abundances and abundances of their decay products with results from improved propagation models in order to discuss the amount of electron-capture decay and subsequent acceleration that may have occurred during propagation.

  2. Electron transfer and capture dynamics in ZnSe quantum wells grown on GaAs

    SciTech Connect

    Dongol, A.; Wagner, H. P.

    2013-12-04

    We investigate the transfer and capture dynamics of electrons in phase coherent photorefractive ZnSe quantum wells grown on GaAs using degenerate three-beam four-wave-mixing. The measurements reveal electron capture times by the quantum well in the order of several tens of picoseconds and a transit time of approximately 5 picoseconds from the GaAs substrate through the ZnMgSe barrier.

  3. Quantum electron-acoustic double layers in two electron species quantum plasma

    SciTech Connect

    Sah, Om Prakash

    2009-01-15

    The existence and the characteristic properties of electron-acoustic double layers are investigated in three component unmagnetized dense quantum plasmas consisting of stationary background ions and two electron populations: one 'cold' and the other 'hot'. Using the one-dimensional quantum hydrodynamic model and the reductive perturbation technique, a generalized form of nonlinear quantum Korteweg-de Vries equation governing the dynamics of weak electron acoustic double layers is derived. A stationary solution of this equation is obtained to discuss the existence criteria of different types of double layers and their characteristic properties. It is shown that two types of compressive double layers: one in the lower {delta}-parameter region and the other at the higher {delta}-parameter region, along with rarefactive double layers in the intermediate region, may exist, where {delta}=n{sub ec0}/n{sub eh0} is the ratio of unperturbed cold to hot electron densities. The width, the amplitude, and the velocity of these double layers are significantly affected by the {delta}-parameter. The relevance of the present investigation is also discussed.

  4. Evaluation of Data Entry Errors and Data Changes to an Electronic Data Capture Clinical Trial Database.

    PubMed

    Mitchel, Jules T; Kim, Yong Joong; Choi, Joonhyuk; Park, Glen; Cappi, Silvana; Horn, David; Kist, Morgan; D Agostino, Ralph B

    2011-07-01

    Monitoring of clinical trials includes several disciplines, stakeholders, and skill sets. The aim of the present study was to identify database changes and data entry errors to an electronic data capture (EDC) clinical trial database, and to access the impact of the changes. To accomblish the aim, Target e*CRF was used as the EDC tool for a multinational, dose-finding, multicenter, double-blind, randomized, parallel, placebo-controlled trial to investigate efficacy and safety of a new treatment in men with lower urinary tract symptoms associated with benign prostatic hyperplasia. The main errors observed were simple transcription errors from the paper source documents to the EDC database. This observation was to be expected, since every transaction has an inherant error rate. What and how to monitor must be assessed within the risk-based monitoring section of the comprehensive data monitoring plan. With the advent of direct data entry, and the elimination of the requirement to transcribe from a paper source record to an EDC system, error rates should go down dramatically. In addition, protocol violations and data outside the normal range can be identified at the time of data entry and not days, weeks, and months after the fact. PMID:24058221

  5. The calorimetric spectrum of the electron-capture decay of 163Ho. The spectral endpoint region

    NASA Astrophysics Data System (ADS)

    De Rújula, A.; Lusignoli, M.

    2016-05-01

    The electron-neutrino mass (or masses and mixing angles) may be directly measurable in weak electron-capture decays. The favoured experimental technique is "calorimetric". The optimal nuclide is 163Ho, and several experiments (ECHo, HOLMES and NuMECS) are currently studying its decay. The most relevant range of the calorimetric-energy spectrum extends for the last few hundred eV below its endpoint. It has not yet been well measured. We explore the theory, mainly in the cited range, of electron capture in 163Ho decay. A so far neglected process turns out to be most relevant: electron-capture accompanied by the shake-off of a second electron. Our two main conclusions are very encouraging: the counting rate close to the endpoint may be more than an order of magnitude larger than previously expected; the "pile-up" problem may be significantly reduced.

  6. Single electron tunneling in double and triple quantum wells

    NASA Astrophysics Data System (ADS)

    Filikhin, I.; Karoui, A.; Vlahovic, B.

    2016-03-01

    Electron localization and tunneling in laterally distributed double quantum well (DQW) and triple quantum well (TQW) are studied. Triangular configuration for the TQWs as well as various quantum well (QW) shapes and asymmetry are considered. The effect of adding a third well to a DQW is investigated as a weakly coupled system. InAs/GaAs DQWs and TQWs were modeled using single subband effective mass approach with effective potential simulating the strain effect. Electron localization dynamics in DQW and TQW over the whole spectrum is studied by varying the inter-dot distances. The electron tunneling appeared highly sensitive to small violations of the DQW mirror symmetry. We show that the presence of a third dot increases the tunneling in the DQW. The dependence of the tunneling in quantum dot (QD) arrays on inter-dot distances is also discussed.

  7. Ultra-fast electron capture by electrosterically-stabilized gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Ghandi, Khashayar; Findlater, Alexander D.; Mahimwalla, Zahid; MacNeil, Connor S.; Awoonor-Williams, Ernest; Zahariev, Federico; Gordon, Mark S.

    2015-07-01

    Ultra-fast pre-solvated electron capture has been observed for aqueous solutions of room-temperature ionic liquid (RTIL) surface-stabilized gold nanoparticles (AuNPs; ~9 nm). The extraordinarily large inverse temperature dependent rate constants (ke ~ 5 × 1014 M-1 s-1) measured for the capture of electrons in solution suggest electron capture by the AuNP surface that is on the timescale of, and therefore in competition with, electron solvation and electron-cation recombination reactions. The observed electron transfer rates challenge the conventional notion that radiation induced biological damage would be enhanced in the presence of AuNPs. On the contrary, AuNPs stabilized by non-covalently bonded ligands demonstrate the potential to quench radiation-induced electrons, indicating potential applications in fields ranging from radiation therapy to heterogeneous catalysis.Ultra-fast pre-solvated electron capture has been observed for aqueous solutions of room-temperature ionic liquid (RTIL) surface-stabilized gold nanoparticles (AuNPs; ~9 nm). The extraordinarily large inverse temperature dependent rate constants (ke ~ 5 × 1014 M-1 s-1) measured for the capture of electrons in solution suggest electron capture by the AuNP surface that is on the timescale of, and therefore in competition with, electron solvation and electron-cation recombination reactions. The observed electron transfer rates challenge the conventional notion that radiation induced biological damage would be enhanced in the presence of AuNPs. On the contrary, AuNPs stabilized by non-covalently bonded ligands demonstrate the potential to quench radiation-induced electrons, indicating potential applications in fields ranging from radiation therapy to heterogeneous catalysis. Electronic supplementary information (ESI) available: Calculations and procedure for the synthesis and determination of the gold nanoparticle concentration, μSR sample preparation, determination of rate constants for electron

  8. A low energy ion source for electron capture spectroscopy

    SciTech Connect

    Tusche, C.; Kirschner, J.

    2014-06-15

    We report on the design of an ion source for the production of single and double charged Helium ions with kinetic energies in the range from 300 eV down to 5 eV. The construction is based on a commercial sputter ion gun equipped with a Wien-filter for mass/charge separation. Retardation of the ions from the ionizer potential (2 keV) takes place completely within the lens system of the sputter gun, without modification of original parts. For 15 eV He{sup +} ions, the design allows for beam currents up to 30 nA, limited by the space charge repulsion in the beam. For He{sup 2+} operation, we obtain a beam current of 320 pA at 30 eV, and 46 pA at 5 eV beam energy, respectively. In addition, operating parameters can be optimized for a significant contribution of metastable He*{sup +} (2s) ions.

  9. On the cascade capture of electrons at donors in GaAs quantum wells

    SciTech Connect

    Aleshkin, V. Ya.

    2015-09-15

    The impact parameter for the cascade capture of electrons at a charged donor in a GaAs quantum well is calculated. A simple approximate analytical expression for the impact parameter is suggested. The temperature dependence of the impact parameter for the case of electron scattering by the piezoelectric potential of acoustic phonons is determined.

  10. Laser-Phase Dependence for Electron Capture in Laser-Assisted Proton -- Hydrogen Collisions

    NASA Astrophysics Data System (ADS)

    Niederhausen, Thomas; Thumm, Uwe

    2006-05-01

    We calculate electron capture probabilities for ion--atom collisions in a strong laser field (5x10^13 W/cm^2) by numerically solving the 3-dimensional time--dependent Schr"odinger equation. For circularly polarized laser fields and an impact energy of 1.2 keV, we find a substantial modification of the electronic dynamics in the p--H collision system as compared to field-free collisions. In particular, we observe a strong dependence on the laser phase and the impact parameter for electron capture, which can be explained using semi-classical arguments.

  11. Electron capture in collisions of Al2+ ions with He atoms at intermediate energies

    NASA Astrophysics Data System (ADS)

    Watanabe, A.; Sato, H.; Gu, J. P.; Hirsch, G.; Buenker, R. J.; Kimura, M.

    2001-09-01

    Electron capture resulting from collisions of Al2+ ions with He atoms from 0.15 to 1000 keV/u is investigated using a molecular-orbital representation within a semiclassical frame. Molecular electronic states and corresponding couplings are determined by the ALCHEMY program. Sixteen molecular states all connecting to single-electron-capture processes are included, and hence radial and rotational couplings among these channels are fully considered. The trajectory effect arising from the straight-line, Coulomb, and ground-state potential trajectories for electron-capture and excitation processes is carefully assessed. The electron-capture cross section by ground-state Al2+(2S) ions slowly increases before it reaches a maximum of 1.3×10-16 cm2 at 100 keV/u. Those for metastable Al2+(2P) ions sharply increase with increasing energy, and reach a peak at 1 keV/u with a value of 1.5×10-16 cm2. The earlier experimental data are found to be larger by an order of magnitude although their energy dependence is in good accord with the present result. Excitation cross sections for both the ground and metastable states are found to be much larger by a factor of 2-3 than corresponding capture cross sections above 1 keV/u although they become comparable below this energy.

  12. Development of Holmium-163 Electron-Capture Spectroscopy with Transition-Edge Sensors

    NASA Astrophysics Data System (ADS)

    Croce, M. P.; Rabin, M. W.; Mocko, V.; Kunde, G. J.; Birnbaum, E. R.; Bond, E. M.; Engle, J. W.; Hoover, A. S.; Nortier, F. M.; Pollington, A. D.; Taylor, W. A.; Weisse-Bernstein, N. R.; Wolfsberg, L. E.; Hays-Wehle, J. P.; Schmidt, D. R.; Swetz, D. S.; Ullom, J. N.; Barnhart, T. E.; Nickles, R. J.

    2016-08-01

    Calorimetric decay energy spectroscopy of electron-capture-decaying isotopes is a promising method to achieve the sensitivity required for electron neutrino mass measurement. The very low total nuclear decay energy (Q_EC < 3 keV) and short half-life (4570 years) of ^{163}Ho make it attractive for high-precision electron-capture spectroscopy (ECS) near the kinematic endpoint, where the neutrino momentum goes to zero. In the ECS approach, an electron-capture-decaying isotope is embedded inside a microcalorimeter designed to capture and measure the energy of all the decay radiation except that of the escaping neutrino. We have developed a complete process for proton irradiation-based isotope production, isolation, and purification of ^{163}Ho. We have developed transition-edge sensors for this measurement and methods for incorporating ^{163}Ho into high-resolution microcalorimeters, and have measured the electron-capture spectrum of ^{163}Ho. We present our work in these areas and discuss the measured spectrum and its comparison to current theory.

  13. Development of Holmium-163 Electron-Capture Spectroscopy with Transition-Edge Sensors

    NASA Astrophysics Data System (ADS)

    Croce, M. P.; Rabin, M. W.; Mocko, V.; Kunde, G. J.; Birnbaum, E. R.; Bond, E. M.; Engle, J. W.; Hoover, A. S.; Nortier, F. M.; Pollington, A. D.; Taylor, W. A.; Weisse-Bernstein, N. R.; Wolfsberg, L. E.; Hays-Wehle, J. P.; Schmidt, D. R.; Swetz, D. S.; Ullom, J. N.; Barnhart, T. E.; Nickles, R. J.

    2016-01-01

    Calorimetric decay energy spectroscopy of electron-capture-decaying isotopes is a promising method to achieve the sensitivity required for electron neutrino mass measurement. The very low total nuclear decay energy (Q_EC < 3 keV) and short half-life (4570 years) of ^{163} Ho make it attractive for high-precision electron-capture spectroscopy (ECS) near the kinematic endpoint, where the neutrino momentum goes to zero. In the ECS approach, an electron-capture-decaying isotope is embedded inside a microcalorimeter designed to capture and measure the energy of all the decay radiation except that of the escaping neutrino. We have developed a complete process for proton irradiation-based isotope production, isolation, and purification of ^{163} Ho. We have developed transition-edge sensors for this measurement and methods for incorporating ^{163} Ho into high-resolution microcalorimeters, and have measured the electron-capture spectrum of ^{163} Ho. We present our work in these areas and discuss the measured spectrum and its comparison to current theory.

  14. Electron capture of dopants in two-photonic ionization in a poly(methyl methacrylate) solid

    SciTech Connect

    Tsuchida, Akira; Sakai, Wataru; Nakano, Mitsuru; Yamamoto, Masahide

    1992-10-29

    Behavior of the electron produced by two-photonic excitation of an aromatic donor in a poly(methyl methacrylate) solid was studied by the addition of the electron scavengers to the system. According to the Perrin type analysis for the two-photonically ejected electron, the capture radii (R{sub c}) of the scavengers examined were estimated to be from 8 to 40 {Angstrom}. For the two-photonically ejected electrons, R{sub c} is a capture radius for thermalized electrons. In this case the parent electron donor is not necessarily within this radius. On the other hand, for the fluorescence quenching, the distance between the donor and acceptor is within the static quenching radius (R{sub q}) of the donor. 13 refs., 4 figs., 2 tabs.

  15. Radiative Electron Capture in the First-Forbidden Unique Decay of 81Kr

    SciTech Connect

    Mianowski, S.; Werner-Malento, E.; Korgul, A.; Pomorski, M.; Pachucki, K.; Pfutzner, M.; Szweryn, B.; Zylicz, J.; Hornshoj, P.; Nilsson, T.; Rykaczewski, Krzysztof Piotr

    2010-01-01

    The photon spectrum accompanying the orbital K-electron capture in the first-forbidden unique decay of 81Kr was measured.The total radiation intensity for photon energies larger than 50 keVwas found to be 1.42(22) 10 4 per K capture. Both the shape of the spectrum and its intensity relative to the ordinary, nonradiative capture rate are compared to theoretical predictions. The best agreement is found for the recently developed model that employs the length gauge for the electromagnetic field.

  16. Level-resolved quantum statistical theory of electron capture into many-electron compound resonances in highly charged ions

    NASA Astrophysics Data System (ADS)

    Berengut, J. C.; Harabati, C.; Dzuba, V. A.; Flambaum, V. V.; Gribakin, G. F.

    2015-12-01

    The strong mixing of many-electron basis states in excited atoms and ions with open f shells results in very large numbers of complex, chaotic eigenstates that cannot be computed to any degree of accuracy. Describing the processes which involve such states requires the use of a statistical theory. Electron capture into these "compound resonances" leads to electron-ion recombination rates that are orders of magnitude greater than those of direct, radiative recombination and cannot be described by standard theories of dielectronic recombination. Previous statistical theories considered this as a two-electron capture process which populates a pair of single-particle orbitals, followed by "spreading" of the two-electron states into chaotically mixed eigenstates. This method is similar to a configuration-average approach because it neglects potentially important effects of spectator electrons and conservation of total angular momentum. In this work we develop a statistical theory which considers electron capture into "doorway" states with definite angular momentum obtained by the configuration interaction method. We apply this approach to electron recombination with W20 +, considering 2 ×106 doorway states. Despite strong effects from the spectator electrons, we find that the results of the earlier theories largely hold. Finally, we extract the fluorescence yield (the probability of photoemission and hence recombination) by comparison with experiment.

  17. Shigella flexneri Spa15 Crystal Structure Verified in Solution by Double Electron Electron Resonance

    PubMed Central

    Lillington, James E.D.; Lovett, Janet E.; Johnson, Steven; Roversi, Pietro; Timmel, Christiane R.; Lea, Susan M.

    2011-01-01

    Shigella flexneri Spa15 is a chaperone of the type 3 secretion system, which binds a number of effectors to ensure their stabilization prior to secretion. One of these effectors is IpgB1, a mimic of the human Ras-like Rho guanosine triphosphatase RhoG. In this study, Spa15 alone and in complex with IpgB1 has been studied by double electron electron resonance, an experiment that gives distance information showing the spacial separation of attached spin labels. This distance is explained by determining the crystal structure of the spin-labeled Spa15 where labels are seen to be buried in hydrophobic pockets. The double electron electron resonance experiment on the Spa15 complex with IpgB1 shows that IpgB1 does not bind Spa15 in the same way as is seen in the homologous Salmonella sp. chaperone:effector complex InvB:SipA. PMID:21075116

  18. Evaluation and optimization of electron capture dissociation efficiency in fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    McFarland, Melinda A; Chalmers, Michael J; Quinn, John P; Hendrickson, Christopher L; Marshall, Alan G

    2005-07-01

    Electron capture dissociation (ECD) efficiency has typically been lower than for other dissociation techniques. Here we characterize experimental factors that limit ECD and seek to improve its efficiency. Efficiency of precursor to product ion conversion was measured for a range of peptide (approximately 15% efficiency) and protein (approximately 33% efficiency) ions of differing sizes and charge states. Conversion of precursor ions to products depends on electron irradiation period and maximizes at approximately 5-30 ms. The optimal irradiation period scales inversely with charge state. We demonstrate that reflection of electrons through the ICR cell is more efficient and robust than a single pass, because electrons can cool to the optimal energy for capture, which allows for a wide range of initial electron energy. Further, efficient ECD with reflected electrons requires only a short (approximately 500 micros) irradiation period followed by an appropriate delay for cooling and interaction. Reflection of the electron beam results in electrons trapped in or near the ICR cell and thus requires a brief (approximately 50 micros) purge for successful mass spectral acquisition. Further electron irradiation of refractory precursor ions did not result in further dissociation. Possibly the ion cloud and electron beam are misaligned radially, or the electron beam diameter may be smaller than that of the ion cloud such that remaining precursor ions do not overlap with the electron beam. Several ion manipulation techniques and use of a large, movable dispenser cathode reduce the possibility that misalignment of the ion and electron beams limits ECD efficiency. PMID:15914017

  19. Winter and summer home ranges and core use areas of double-crested cormorants captured near aquaculture facilities in the southeastern United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Migration patterns of Double-crested Cormorants (Phalacrocorax auritus) wintering in the southeastern United States are poorly understood. Movement data was analyzed from 28 cormorants captured in Alabama, Arkansas, Louisiana, and Mississippi and equipped with satellite transmitters. Four (3 immatur...

  20. Thermally activated electron capture by mobile protons in SiO{sub 2} thin films

    SciTech Connect

    Vanheusden, K.; Karna, S.P.; Pugh, R.D.; Warren, W.L.; Fleetwood, D.M.; Devine, R.A.

    1998-01-01

    The annihilation of mobile protons in thin SiO{sub 2} films by capture of ultraviolet-excited electrons has been analyzed for temperatures between 77 and 500 K. We observe a strong increase in proton annihilation with increasing temperature, and derive an activation energy for electron capture of about 0.2 eV. Based on quantum chemical [(OH){sub 3}Si]{sub 2}{endash}O{endash}H{sup +} cluster calculations, we suggest photoexcitation of electrons from excited vibrational states of the ground electronic (valence band) state to a nearby excited electronic (SiO{sub 2} gap) state. It is argued that the latter excitation can result in H{sup 0} formation at elevated temperatures. {copyright} {ital 1998 American Institute of Physics.}

  1. Note: Consecutive capture of images of ions and electrons using high-voltage vacuum relay

    NASA Astrophysics Data System (ADS)

    Yamada, S.; Himura, H.

    2016-03-01

    For the first time, images of both ions and electrons appearing on a fluorescent screen attached to a micro-channel plate (MCP) [S. Nakata et al., "Applicability of micro-channel plate followed by phosphor screen to charged particles," Rev. Sci. Instrum. (submitted)] were captured in one attempt. The profile of electrostatic potential applied externally to the MCP with the fluorescent screen was quickly changed using a high-voltage vacuum relay. This method allows consecutive images of ions and electrons to be successfully captured.

  2. Measurement of θ 13 in Double Chooz using neutron captures on hydrogen with novel background rejection techniques

    NASA Astrophysics Data System (ADS)

    Abe, Y.; Appel, S.; Abrahão, T.; Almazan, H.; Alt, C.; dos Anjos, J. C.; Barriere, J. C.; Baussan, E.; Bekman, I.; Bergevin, M.; Bezerra, T. J. C.; Bezrukov, L.; Blucher, E.; Brugière, T.; Buck, C.; Busenitz, J.; Cabrera, A.; Camilleri, L.; Carr, R.; Cerrada, M.; Chauveau, E.; Chimenti, P.; Collin, A. P.; Conrad, J. M.; Crespo-Anadón, J. I.; Crum, K.; Cucoanes, A. S.; Damon, E.; Dawson, J. V.; Dhooghe, J.; Dietrich, D.; Djurcic, Z.; Dracos, M.; Etenko, A.; Fallot, M.; von Feilitzsch, F.; Felde, J.; Fernandes, S. M.; Fischer, V.; Franco, D.; Franke, M.; Furuta, H.; Gil-Botella, I.; Giot, L.; Göger-Neff, M.; Gomez, H.; Gonzalez, L. F. G.; Goodenough, L.; Goodman, M. C.; Haag, N.; Hara, T.; Haser, J.; Hellwig, D.; Hofmann, M.; Horton-Smith, G. A.; Hourlier, A.; Ishitsuka, M.; Jochum, J.; Jollet, C.; Kaether, F.; Kalousis, L. N.; Kamyshkov, Y.; Kaneda, M.; Kaplan, D. M.; Kawasaki, T.; Kemp, E.; de Kerret, H.; Kryn, D.; Kuze, M.; Lachenmaier, T.; Lane, C. E.; Lasserre, T.; Letourneau, A.; Lhuillier, D.; Lima, H. P.; Lindner, M.; López-Castaño, J. M.; LoSecco, J. M.; Lubsandorzhiev, B.; Lucht, S.; Maeda, J.; Mariani, C.; Maricic, J.; Martino, J.; Matsubara, T.; Mention, G.; Meregaglia, A.; Miletic, T.; Milincic, R.; Minotti, A.; Nagasaka, Y.; Navas-Nicolás, D.; Novella, P.; Oberauer, L.; Obolensky, M.; Onillon, A.; Osborn, A.; Palomares, C.; Pepe, I. M.; Perasso, S.; Porta, A.; Pronost, G.; Reichenbacher, J.; Reinhold, B.; Röhling, M.; Roncin, R.; Rybolt, B.; Sakamoto, Y.; Santorelli, R.; Schilithz, A. C.; Schönert, S.; Schoppmann, S.; Shaevitz, M. H.; Sharankova, R.; Shrestha, D.; Sibille, V.; Sinev, V.; Skorokhvatov, M.; Smith, E.; Soiron, M.; Spitz, J.; Stahl, A.; Stancu, I.; Stokes, L. F. F.; Strait, M.; Suekane, F.; Sukhotin, S.; Sumiyoshi, T.; Sun, Y.; Svoboda, R.; Terao, K.; Tonazzo, A.; Thi, H. H. Trinh; Valdiviesso, G.; Vassilopoulos, N.; Veyssiere, C.; Vivier, M.; Wagner, S.; Walsh, N.; Watanabe, H.; Wiebusch, C.; Wurm, M.; Yang, G.; Yermia, F.; Zimmer, V.

    2016-01-01

    The Double Chooz collaboration presents a measurement of the neutrino mixing angle θ 13 using reactor overline{νe} observed via the inverse beta decay reaction in which the neutron is captured on hydrogen. This measurement is based on 462.72 live days data, approximately twice as much data as in the previous such analysis, collected with a detector positioned at an average distance of 1050 m from two reactor cores. Several novel techniques have been developed to achieve significant reductions of the backgrounds and systematic uncertainties. Accidental coincidences, the dominant background in this analysis, are suppressed by more than an order of magnitude with respect to our previous publication by a multi-variate analysis. These improvements demonstrate the capability of precise measurement of reactor overline{νe} without gadolinium loading. Spectral distortions from the overline{νe} reactor flux predictions previously reported with the neutron capture on gadolinium events are confirmed in the independent data sample presented here. A value of sin2 2 θ 13 = 0.095 - 0.039 + 0.038 (stat+syst) is obtained from a fit to the observed event rate as a function of the reactor power, a method insensitive to the energy spectrum shape. A simultaneous fit of the hydrogen capture events and of the gadolinium capture events yields a measurement of sin2 2 θ 13 = 0 .088 ± 0 .033(stat+syst). [Figure not available: see fulltext.

  3. Electron exchange and polarization effects on electron captures and neutron emissions by nuclei in white dwarfs and neutron stars

    NASA Astrophysics Data System (ADS)

    Chamel, N.; Fantina, A. F.

    2016-03-01

    In dense stellar environments, nuclei may become unstable against electron captures and/or neutron emissions. These processes are of particular importance for determining the internal constitution of white-dwarf cores and neutron-star crusts. In this paper, the role of electron exchange and polarization effects is studied. In particular, the instability condition for the onset of electron captures and neutron emissions is extended so as to account for electron exchange and polarization. Moreover, general analytical expressions for the corresponding density and pressure are derived. The corrections to the electron-capture threshold in white-dwarf cores are found to be very small. Likewise, the neutron-drip density and pressure in the crusts of accreting and nonaccreting neutron stars are only slightly shifted. Depending on the nuclear mass model employed, electron polarization may change the composition of the crust of nonaccreting neutron stars. On the other hand, the current uncertainties in the masses of neutron-rich Kr and Sr isotopes are found to be more important than electron exchange and polarization effects.

  4. 2013 R&D 100 Award: Movie-mode electron microscope captures nanoscale

    ScienceCinema

    Lagrange, Thomas; Reed, Bryan

    2014-07-21

    A new instrument developed by LLNL scientists and engineers, the Movie Mode Dynamic Transmission Electron Microscope (MM-DTEM), captures billionth-of-a-meter-scale images with frame rates more than 100,000 times faster than those of conventional techniques. The work was done in collaboration with a Pleasanton-based company, Integrated Dynamic Electron Solutions (IDES) Inc. Using this revolutionary imaging technique, a range of fundamental and technologically important material and biological processes can be captured in action, in complete billionth-of-a-meter detail, for the first time. The primary application of MM-DTEM is the direct observation of fast processes, including microstructural changes, phase transformations and chemical reactions, that shape real-world performance of nanostructured materials and potentially biological entities. The instrument could prove especially valuable in the direct observation of macromolecular interactions, such as protein-protein binding and host-pathogen interactions. While an earlier version of the technology, Single Shot-DTEM, could capture a single snapshot of a rapid process, MM-DTEM captures a multiframe movie that reveals complex sequences of events in detail. It is the only existing technology that can capture multiple electron microscopy images in the span of a single microsecond.

  5. 2013 R&D 100 Award: Movie-mode electron microscope captures nanoscale

    SciTech Connect

    Lagrange, Thomas; Reed, Bryan

    2014-04-03

    A new instrument developed by LLNL scientists and engineers, the Movie Mode Dynamic Transmission Electron Microscope (MM-DTEM), captures billionth-of-a-meter-scale images with frame rates more than 100,000 times faster than those of conventional techniques. The work was done in collaboration with a Pleasanton-based company, Integrated Dynamic Electron Solutions (IDES) Inc. Using this revolutionary imaging technique, a range of fundamental and technologically important material and biological processes can be captured in action, in complete billionth-of-a-meter detail, for the first time. The primary application of MM-DTEM is the direct observation of fast processes, including microstructural changes, phase transformations and chemical reactions, that shape real-world performance of nanostructured materials and potentially biological entities. The instrument could prove especially valuable in the direct observation of macromolecular interactions, such as protein-protein binding and host-pathogen interactions. While an earlier version of the technology, Single Shot-DTEM, could capture a single snapshot of a rapid process, MM-DTEM captures a multiframe movie that reveals complex sequences of events in detail. It is the only existing technology that can capture multiple electron microscopy images in the span of a single microsecond.

  6. Reversible Ionic Liquids as Double-Action Solvents for Efficient CO2 Capture

    SciTech Connect

    Eckert, Charles; Liotta, Charles

    2011-09-30

    We have developed a novel class of CO{sub 2} capture solvents, Reversible Ionic Liquids (RevILs), that offer high absorption capacity through two modes of capture: chemical reaction (chemisorption) and physical solubility (physisorption). These solvents are silicon containing alkaline compounds such as silylamines that form a liquid salt (ionic liquid) upon reaction with CO{sub 2}. Subsequently, modest elevations in temperature reverse the reaction and yield pure CO{sub 2} for sequestration. By incorporating Si in the molecules we have reduced the viscosity, thereby improving the mass transfer rates of CO{sub 2} absorption/desorption and decreasing the processing costs for pumping the solvent. In this project, we have made systematic changes to the structure of these compounds to improve several physical and thermodynamic properties important for CO{sub 2} capture. Through these structure-property paradigms, we have obtained a RevIL which requires only a third of the energy required by conventional aqueous MEA process for 90% CO{sub 2} capture.

  7. Reversible Ionic Liquids as Double-Action Solvents for Efficient CO{sub 2} Capture

    SciTech Connect

    Charles Eckert; Charles Liotta

    2011-09-30

    We have developed a novel class of CO{sub 2} capture solvents, Reversible Ionic Liquids (RevILs), that offer high absorption capacity through two modes of capture: chemical reaction (chemisorption) and physical solubility (physisorption). These solvents are silicon containing alkaline compounds such as silylamines that form a liquid salt (ionic liquid) upon reaction with CO{sub 2}. Subsequently, modest elevations in temperature reverse the reaction and yield pure CO{sub 2} for sequestration. By incorporating Si in the molecules we have reduced the viscosity, thereby improving the mass transfer rates of CO{sub 2} absorption/desorption and decreasing the processing costs for pumping the solvent. In this project, we have made systematic changes to the structure of these compounds to improve several physical and thermodynamic properties important for CO{sub 2} capture. Through these structure-property paradigms, we have obtained a RevIL which requires only a third of the energy required by conventional aqueous MEA process for 90% CO{sub 2} capture.

  8. Angular distribution of characteristic photons after radiative electron capture at strong central fields

    SciTech Connect

    Drukarev, E. G.; Ma, X.; Mikhailov, A. I.; Mikhailov, I. A.; Mokler, P. H.

    2006-08-15

    We investigate the difference in the angular distribution of Ly-{alpha}{sub 1} and K{alpha}{sub 1} photons from hydrogenlike and heliumlike ions of uranium after radiative electron capture to the L shell. The strong anisotropy in the former case is changed to a very small one in the latter case. Our calculations support the observation. The effect takes place even in the limiting case of noninteracting electrons, being caused by the Pauli principle.

  9. 78 FR 16531 - Certain Electronic Devices for Capturing and Transmitting Images, and Components Thereof...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-15

    ... Eastman Kodak Company of Rochester, New York. 77 FR 11588-89 (Feb. 27, 2012). The complaint alleges a... COMMISSION Certain Electronic Devices for Capturing and Transmitting Images, and Components Thereof... images, and components thereof. The complaint further alleges that an industry in the United...

  10. The determination of cyclohexylamine in aqueous solutions of sodium cyclamate by electron-capture gas chromatography.

    NASA Technical Reports Server (NTRS)

    Solomon, M. D.; Pereira, W. E.; Duffield, A. M.

    1971-01-01

    A sensitive primary amine assay, capable of detecting 10 to the minus 11th g and utilizing the determination of the amine N-2,4-dinitrophenyl derivative by electron-capture gas chromatography is described. The method is exemplified by the determination of cyclohexylamine in sodium cyclamate.

  11. DETERMINATION OF ACRYLAMIDE IN RAT SERUM AND SCIATIC NERVE BY GAS CHROMATOGRAPHY-ELECTRON-CAPTURE DETECTION

    EPA Science Inventory

    A modified method for the derivatization and analysis of acrylamide as 2-bromopropenamide by gas chromatography/electron capture detection was validated in serum and sciatic nerve from rats. he method was accurate and precise over the concentration range of 2240 to 74700 ppm (w/v...

  12. Visualization of Distance Distribution from Pulsed Double Electron-Electron Resonance Data

    SciTech Connect

    Bowman, Michael K.; Maryasov, Alexander G.; Kim, Nak-Kyoon; DeRose, Victoria J.

    2004-01-01

    Double electron-electron resonance (DEER), also known as pulsed electron-electron double resonance (PELDOR), is a time-domain electron paramagnetic resonance method that can measure the weak dipole-dipole interactions between unpaired electrons. DEER has been applied to discrete pairs of free radicals in biological macromolecules and to clusters containing small numbers of free radicals in polymers and irradiated materials. The goal of such work is to determine the distance or distribution of distances between radicals, which is an underdetermined problem. That is, the spectrum of dipolar interactions can be readily calculated for any distribution of free radicals, but there are many, quite different distributions of radicals that could produce the same experimental dipolar spectrum. This paper describes two methods that are useful for approximating the distance distributions for the large subset of cases in which the mutual orientations of the free radicals are uncorrelated and the width of the distribution is more than a few percent of its mean. The first method relies on a coordinate transformation and is parameter free, while the second is based on iterative least-squares with Tikhonov regularization. Both methods are useful in DEER studies of spin labeled biomolecules containing more than two labels.

  13. A mobile and asynchronous electronic data capture system for epidemiologic studies.

    PubMed

    Meyer, Jens; Fredrich, Daniel; Piegsa, Jens; Habes, Mohamad; van den Berg, Neeltje; Hoffmann, Wolfgang

    2013-06-01

    A Central Data Management (CDM) system based on electronic data capture (EDC) software and study specific databases is an essential component for assessment and management of large data volumes in epidemiologic studies. Conventional CDM systems using web applications for data capture depend on permanent access to a network. However, in many study settings permanent network access cannot be guaranteed, e.g. when participants/patients are visited in their homes. In such cases a different concept for data capture is needed. The utilized EDC software must be able to ensure data capture as stand-alone instance and to synchronize captured data with the server at a later point in time. This article describes the design of the mobile information capture (MInCa) system an EDC software meeting these requirements. In particular, we focus on client and server design, data synchronization, and data privacy as well as data security measures. The MInCa software has already proven its efficiency in epidemiologic studies revealing strengths and weaknesses concerning both concept and practical application which will be addressed in this article. PMID:23195493

  14. Determination of electrostatic potentials at biological interfaces using electron-electron double resonance.

    PubMed Central

    Shin, Y K; Hubbell, W L

    1992-01-01

    A new general method for the determination of electrostatic potentials at biological surfaces is presented. The approach is based on measurement of the collision frequency of a charged nitroxide in solution with a nitroxide fixed to the surface at the point of interest. The collision frequency is determined with 14N:15N double label electron-electron double resonance (ELDOR). As a test, the method is shown to give values for phospholipid bilayer surface potentials consistent with the Gouy-Chapman theory, a simple model shown by many independent tests to accurately describe charged, planar surfaces. In addition, the method is applied to determine the electrostatic potential near the surface of DNA. The results indicate that the potential is significantly smaller than that predicted from Poisson-Boltzmann analysis, but is in qualitative agreement with that predicted by Manning's theory of counter ion condensation. The method is readily extended to measurement of surface potentials of proteins. PMID:1319760

  15. Electron transport in coupled double quantum wells and wires

    SciTech Connect

    Harff, N.E.; Simmons, J.A.; Lyo, S.K.

    1997-04-01

    Due to inter-quantum well tunneling, coupled double quantum wells (DQWs) contain an extra degree of electronic freedom in the growth direction, giving rise to new transport phenomena not found in single electron layers. This report describes work done on coupled DQWs subject to inplane magnetic fields B{sub {parallel}}, and is based on the lead author`s doctoral thesis, successfully defended at Oregon State University on March 4, 1997. First, the conductance of closely coupled DQWs in B{sub {parallel}} is studied. B{sub {parallel}}-induced distortions in the dispersion, the density of states, and the Fermi surface are described both theoretically and experimentally, with particular attention paid to the dispersion anticrossing and resulting partial energy gap. Measurements of giant distortions in the effective mass are found to agree with theoretical calculations. Second, the Landau level spectra of coupled DQWs in tilted magnetic fields is studied. The magnetoresistance oscillations show complex beating as Landau levels from the two Fermi surface components cross the Fermi level. A third set of oscillations resulting from magnetic breakdown is observed. A semiclassical calculation of the Landau level spectra is then performed, and shown to agree exceptionally well with the data. Finally, quantum wires and quantum point contacts formed in DQW structures are investigated. Anticrossings of the one-dimensional DQW dispersion curves are predicted to have interesting transport effects in these devices. Difficulties in sample fabrication have to date prevented experimental verification. However, recently developed techniques to overcome these difficulties are described.

  16. The Role of Electron Captures in Chandrasekhar-Mass Models for Type Ia Supernovae

    SciTech Connect

    Brachwitz, Franziska; Dean, David J.; Hix, W. Raphael; Iwamoto, Koichi; Langanke, Karlheinz; Martinez-Pinedo, Gabriel; Nomoto, Ken'ichi; Strayer, Michael R.; Thielemann, Friedrich-K.; Umeda, Hideyuki

    2000-06-20

    The Chandrasekhar-mass model for Type Ia supernovae (SNe Ia) has received increasing support from recent comparisons of observations with light-curve predictions and modeling of synthetic spectra. It explains SN Ia events via thermonuclear explosions of accreting white dwarfs in binary stellar systems, being caused by central carbon ignition when the white dwarf approaches the Chandrasekhar mass. As the electron gas in white dwarfs is degenerate, characterized by high Fermi energies for the high-density regions in the center, electron capture on intermediate-mass and Fe group nuclei plays an important role in explosive burning. Electron capture affects the central electron fraction Y{sub e}, which determines the composition of the ejecta from such explosions. Up to the present, astrophysical tabulations based on shell model matrix elements were available only for light nuclei in the sd-shell. Recently, new shell model Monte Carlo and large-scale shell model diagonalization calculations have also been performed for pf-shell nuclei. These lead in general to a reduction of electron capture rates in comparison with previous, more phenomenological, approaches. Making use of these new shell model-based rates, we present the first results for the composition of Fe group nuclei produced in the central regions of SNe Ia and possible changes in the constraints on model parameters like ignition densities {rho}ign and burning front speeds v{sub def}. (c) 2000 The American Astronomical Society.

  17. Electron cyclotron maser emission from double footpoints in solar flares

    NASA Astrophysics Data System (ADS)

    Conway, A. J.; Willes, A. J.

    2000-03-01

    It is now known from Yohkoh Hard X-ray Telescope observations that double (or even multiple) hard X-ray sources in flares are a common occurrence. These sources, which are positioned at the feet of coronal soft X-ray loops, are synchronised to within 0.1s and have similar spectra, strongly suggesting that they are produced by a single population of electrons accelerated/injected at some point in the loop. As this electron population is reflected from the converging footpoint magnetic fields, it develops a loss cone and an electron-cyclotron maser instability may ensue. The frequency and intensity of such emission depends on the relative strengths and orientations of the footpoint magnetic fields. In this paper, we investigate the case of an almost symmetric loop to assess whether observable maser emission from both footpoints can result. In particular, we relate this theory to existing observations of solar microwave spike bursts which have two distinct frequency bands that are of non-integer ratio and comparable intensities. We conclude that differing footpoint magnetic field inclinations cannot explain the observations (specifically the comparable intensities), but that it is possible for slightly differing footpoint magnetic field strengths to explain the observations. The pros and cons of this `geometric' model are then compared with a previous model of these events, which explained them in terms of the growth and then coalescence of Bernstein waves. We conclude that both interpretations seem plausible given current observations, but present a list of observable features that might be used discriminate between them in flare observations of the next solar maximum.

  18. Calculations on Electron Capture in Low Energy Ion-Molecule Collisions

    SciTech Connect

    Stancil, P.C.; Zygelman, B.; Kirby, K.

    1997-12-31

    Recent progress on the application of a quantal, molecular-orbital, close-coupling approach to the calculation of electron capture in collisions of multiply charged ions with molecules is discussed. Preliminary results for single electron capture by N{sup 2+} with H{sub 2} are presented. Electron capture by multiply charged ions colliding with H{sub 2} is an important process in laboratory and astrophysical plasmas. It provides a recombination mechanism for multiply charged ions in x-ray ionized astronomical environments which may have sparse electron and atomic hydrogen abundances. In the divertor region of a tokamak fusion device, charge exchange of impurity ions with H{sub 2} plays a role in the ionization balance and the production of radiative energy loss leading to cooling, X-ray and ultraviolet auroral emission from Jupiter is believed to be due to charge exchange of O and S ions with H{sub 2} in the Jovian atmosphere. Solar wind ions interacting with cometary molecules may have produced the x-rays observed from Comet Hyakutake. In order to model and understand the behavior of these environments, it is necessary to obtain total, electronic state-selective (ESS), and vibrational (or rotational) state-selective (VSS) capture cross sections for collision energies as low as 10 meV/amu to as high as 100 keV/amu in some instances. Fortunately, charge transfer with molecular targets has received considerable experimental attention. Numerous measurements have been made with flow tubes, ion traps, and ion beams. Flow tube and ion trap studies generally provide information on rate coefficients for temperatures between 800 K and 20,000 K. In this article, we report on the progress of our group in implementing a quantum-mechanical Molecular Orbital Close Coupling (MOCC) approach to the study of electron capture by multiply charged ions in collisions with molecules. We illustrate this with a preliminary investigation of Single Electron Capture (SEC) by N{sup 2+} with H

  19. Pair production and electron capture in relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Lee, R. J.; Mullan, J. V.; McCann, J. F.; Crothers, D. S.

    2001-06-01

    Results are presented for simulations of electron-positron pair production in relativistic heavy-ion collisions leading to electron capture and positron ejection. We apply a two-center relativistic continuum distorted-wave model to represent the electron or positron dynamics during the collision process. The results are compared with experimental cross-section data for La57+ and Au79+ impact on gold, silver, and copper targets. The theory is in good agreement with experiment for La57+ impact, verifying the result that the process increases in importance with both collision energy and target atomic number, and improves upon previous simulations of this process.

  20. How getting noticed helps getting on: successful attention capture doubles children's cooperative play

    PubMed Central

    Yuill, Nicola; Hinske, Steve; Williams, Sophie E.; Leith, Georgia

    2014-01-01

    Cooperative social interaction is a complex skill that involves maintaining shared attention and continually negotiating a common frame of reference. Privileged in human evolution, cooperation provides support for the development of social-cognitive skills. We hypothesize that providing audio support for capturing playmates' attention will increase cooperative play in groups of young children. Attention capture was manipulated via an audio-augmented toy to boost children's attention bids. Study 1 (48 6- to 11-year-olds) showed that the augmented toy yielded significantly more cooperative play in triads compared to the same toy without augmentation. In Study 2 (33 7- to 9-year-olds) the augmented toy supported greater success of attention bids, which were associated with longer cooperative play, associated in turn with better group narratives. The results show how cooperation requires moment-by-moment coordination of attention and how we can manipulate environments to reveal and support mechanisms of social interaction. Our findings have implications for understanding the role of joint attention in the development of cooperative action and shared understanding. PMID:24904453

  1. How getting noticed helps getting on: successful attention capture doubles children's cooperative play.

    PubMed

    Yuill, Nicola; Hinske, Steve; Williams, Sophie E; Leith, Georgia

    2014-01-01

    Cooperative social interaction is a complex skill that involves maintaining shared attention and continually negotiating a common frame of reference. Privileged in human evolution, cooperation provides support for the development of social-cognitive skills. We hypothesize that providing audio support for capturing playmates' attention will increase cooperative play in groups of young children. Attention capture was manipulated via an audio-augmented toy to boost children's attention bids. Study 1 (48 6- to 11-year-olds) showed that the augmented toy yielded significantly more cooperative play in triads compared to the same toy without augmentation. In Study 2 (33 7- to 9-year-olds) the augmented toy supported greater success of attention bids, which were associated with longer cooperative play, associated in turn with better group narratives. The results show how cooperation requires moment-by-moment coordination of attention and how we can manipulate environments to reveal and support mechanisms of social interaction. Our findings have implications for understanding the role of joint attention in the development of cooperative action and shared understanding. PMID:24904453

  2. 75 FR 8115 - In the Matter of Certain Electronic Devices Having Image Capture or Display Functionality and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-23

    .... 5,995,767, 5,774,131, and 6,281,895. 74 FR 14157 (2009). The complainant named Eastman Kodak Company... COMMISSION In the Matter of Certain Electronic Devices Having Image Capture or Display Functionality and... sale within the United States after importation of certain electronic devices having image capture...

  3. An electronic documentation system increases diagnostic code capture for very low birth weight infants.

    PubMed Central

    Porcelli, P. J.

    2001-01-01

    INTRODUCTION: Information describing medical interventions and patient outcome of very low birth weight (VLBW; BW <1500 grams) infants who receive neonatal intensive care is necessary to evaluate the quality of health care. We developed an electronic patient documentation system (EDS) called PCode to identify and select patient diagnostic (DX) codes and compared EDS to the previous paper-based documentation system (PDS). Our hypothesis was that EDS would capture more patient diagnostic codes than PDS. METHODS: PDS was originally developed as a two page 'code sheet' which listed all 275 neonatal diagnoses/management options and corresponding 3-4 character diagnostic (DX) codes, organized by organ system. PDS code sheets were manually completed by one of three trained 'coders' for every neonatal patient. EDS was developed as a Java application with the 'coder' selecting DX codes from drop lists also categorized by organ system. The study intervention was patient code selection using either the PDS or the EDS system. Both systems produced a paper DX code summary. PDS data capture occurred from 11/1997-3/1999 followed by EDS data capture until 8/2000. The primary outcome variable was DX codes captured per patient. Data were analyzed using independent t-test and linear regression. RESULTS: The number of diagnoses increased with decreasing birth weight. After linear regression was applied to control for birth weight, the number of DX codes was 31% greater in the EDS group, 7.2 +/- 2.9 DX codes/patient, p=0.008. There was a trend towards fewer erroneous DX codes in the EDS group. The most common DX codes were hyaline membrane disease, sepsis evaluation and hyperbilirubinemia, as expected for this patient population. CONCLUSIONS: EDS captured more VLBW infant DX codes compared to PDS. These results support the transition toward electronic data documentation for the neonatal clinical environment. Electronically linking PCode to the patient database has been initiated and

  4. Energy distribution of elastically scattered electrons from double layer samples

    NASA Astrophysics Data System (ADS)

    Tőkési, K.; Varga, D.

    2016-02-01

    We present a theoretical description of the spectra of electrons elastically scattered from thin double layered Au-C samples. The analysis is based on the Monte Carlo simulation of the recoil and Doppler effects in reflection and transmission geometries of the scattering at a fixed angle of 44.3 ° and a primary energy of 40 keV. The relativistic correction is taken into account. Besides the experimentally measurable energy distributions the simulations give many partial distributions separately, depending on the number of elastic scatterings (single, and multiple scatterings of different types). Furthermore, we present detailed analytical calculations for the main parameters of the single scattering, taking into account both the ideal scattering geometry, i.e. infinitesimally small angular range, and the effect of the real, finite angular range used in the measurements. We show our results for intensity ratios, peak shifts and broadenings for four cases of measurement geometries and layer thicknesses. While in the peak intensity ratios of gold and carbon for transmission geometries were found to be in good agreement with the results of the single scattering model, especially large deviations were obtained in reflection geometries. The separation of the peaks, depending on the geometry and the thickness, generally smaller, and the peak width generally larger than it can be expected from the nominal values of the primary energy, scattering angle, and mean kinetic energy of the atoms. We also show that the peaks are asymmetric even for the case of the single scattering due to the finite solid angle. Finally, we present a qualitative comparison with the experimental data. We find our resulting energy distribution of elastically scattered electrons to be in good agreement with recent measurements.

  5. Rapid purification of double-stranded DNA by triple-helix-mediated affinity capture

    SciTech Connect

    Ji, H.; Smith, L.M. )

    1993-05-15

    A simple and rapid method for the preparation of highly pure plasmid DNA has been developed. The DNA is directly captured from bacterial cell lysates by formation of a triple-helical structure between the plasmid dsDNA and a 20-base biotinylated oligonucleotide attached to streptavidin-coated magnetic beads and then eluted from the beads in pH 9 buffer solution. No phenol extraction, ethanol precipitation, RNase digestion, or CsCl gradient centrifugation is required. A general purpose cloning vector, pHJ19, was constructed for this application from pUC19 DNA by insertion of a 40-base sequence suitable for triple-helix formation. The approach was also found suitable for the purification of [lambda] bacteriophage DNA. 32 refs., 6 figs., 1 tab.

  6. Multi-electron coincidence spectroscopy: double photoionization from molecular inner-shell orbitals

    NASA Astrophysics Data System (ADS)

    Hikosaka, Y.; Lablanquie, P.; Penent, F.; Nakano, M.; Ito, K.

    2014-04-01

    We have studied double photoionization from molecular inner-shell orbitals and investigated the properties of the resultant double core-hole states in molecules, by multi-electron coincidence spectroscopy with a magnetic bottle electron spectrometer. A brief summary of our previous studies is presented.

  7. Stellar electron-capture rates calculated with the finite-temperature relativistic random-phase approximation

    SciTech Connect

    Niu, Y. F.; Paar, N.; Vretenar, D.; Meng, J.

    2011-04-15

    We introduce a self-consistent microscopic theoretical framework for modeling the process of electron capture on nuclei in stellar environment, based on relativistic energy density functionals. The finite-temperature relativistic mean-field model is used to calculate the single-nucleon basis and the occupation factors in a target nucleus, and J{sup {pi}}=0{sup {+-}}, 1{sup {+-}}, and 2{sup {+-}} charge-exchange transitions are described by the self-consistent finite-temperature relativistic random-phase approximation. Cross sections and rates are calculated for electron capture on {sup 54,56}Fe and {sup 76,78}Ge in stellar environment, and results compared with predictions of similar and complementary model calculations.

  8. Electron Capture Processes Following Collisions of He^2+ Ions with Molecular Targets

    NASA Astrophysics Data System (ADS)

    Abu-Haija, O.

    2005-05-01

    Energy-gain spectra, absolute state-selective and total cross sections have been measured for single-electron capture processes in collisions of He^2+ ions with O2, H2O, CO2, N2, and NH3 at impact energies between 100 eV and 1600 eV and scattering angles between 0^o and 6^o using the translational energy-gain spectroscopy (TES) technique. As apparent from the translational energy-gain measurements, single-electron capture (SEC) from O2 and H2O proceeds by both dissociative and non-dissociative channels, whereas for N2 and CO2 only dissociative SEC has been observed. However, for NH3 the non-dissociative SEC channel is found to be predominantly populated. Total cross sections have also been compared with available measurements and theoretical calculations based on Landua-Zener model and Demkov model.

  9. Deep defects and their electron-capture cross sections in polymorphous silicon-germanium thin films

    SciTech Connect

    Meaudre, M.; Gueunier-Farret, M.E.; Meaudre, R.; Kleider, J.P.; Vignoli, S.; Canut, B.

    2005-08-01

    Hydrogenated silicon-germanium alloys (SiGe:H) are deposited by plasma-enhanced chemical vapor deposition in a plasma regime close to that of the formation of powder. It is thus possible to obtain nanostructured materials that we call polymorphous materials, pm-Si{sub 1-x}Ge{sub x}:H. Studies of space-charge-limited currents and space-charge relaxation allow to get information on midgap states originating from Ge. It is observed that the electron-capture cross section of states at the Fermi level increases linearly with their concentration. This is supported by modulated photocurrent experiments. Finally, it is shown that the variations of both the Ge dangling bond concentration and their electron-capture cross section with Ge content account for the photoresponse in these materials.

  10. Electron capture in 163Ho, overlap plus exchange corrections and neutrino mass

    NASA Astrophysics Data System (ADS)

    Faessler, Amand; Gastaldo, Loredana; Šimkovic, F.

    2015-01-01

    Holmium 163 offers perhaps the best chance to determine the neutrino mass by electron capture (EC). This contribution treats the EC in 163Holmium completely relativistic for the overlap and exchange corrections and the description of the bolometer spectrum. The theoretical expressions are derived consistently in second quantization with the help of Wick's theorem assuming single Slater determinants for the initial Ho and the final Dy atoms with holes in the final n{{s}1/2} and n{{p}1/2} states. One needs no hand waving arguments to derive the exchange terms. It seems, that for the first time the multiplicity of electrons in the orbital overlaps are included in the numerical treatment. Electron capture {{e}-}+p\\to n+{{ν }e} is proportional to the probability to find the captured electron in the parent atom at the nucleus. Non-relativistically this is only possible for n{{s}1/2} electron states. Relativistically also {{p}1/2} electrons have a probability due to the lower part of the relativistic electron spinor, which does not disappear at the origin. Moreover relativistic effects increase by contraction the electron probability at the nucleus. Capture from other states are suppressed. However they can be allowed with smaller intensity due to finite nuclear size. These probabilities are at least three orders smaller than the EC from 3{{s}1/2} and 3{{p}1/2} states. The purpose of this work is to give a consistent relativistic formulation and treatment of the overlap and exchange corrections for EC in 67163Ho to excited atomic states in 66163Dy and to show the influence of the different configurations in the final Dy states. The overlap and exchange corrections are essential for the calorimetric spectrum of the de-excitation of the hole states in dysprosium. The slope of the upper end of the spectrum, which contains the information on the electron neutrino mass, is different. In addition the effect of the finite energy resolution on the spectrum and on the

  11. Dynamical resonant electron capture in atom surface collisions: H- formation in H-Al(111) collisions

    NASA Astrophysics Data System (ADS)

    Borisov, A. G.; Teillet-Billy, D.; Gauyacq, J. P.

    1992-05-01

    The formation of H- ion by grazing-angle collisions of hydrogen on an Al(111) surface is investigated with the newly developed coupled angular mode method. The capture process involves a dynamical resonant process induced by the collision velocity. All the resonance properties of the H- level in front of an Al(111) surface are determined: position, width, and angular distribution of ejected electrons. The results are shown to account for the recent observations on H- formation by Wyputta, Zimny, and Winter.

  12. β+ Gamow-Teller transition strengths from 46Ti and stellar electron-capture rates.

    PubMed

    Noji, S; Zegers, R G T; Austin, Sam M; Baugher, T; Bazin, D; Brown, B A; Campbell, C M; Cole, A L; Doster, H J; Gade, A; Guess, C J; Gupta, S; Hitt, G W; Langer, C; Lipschutz, S; Lunderberg, E; Meharchand, R; Meisel, Z; Perdikakis, G; Pereira, J; Recchia, F; Schatz, H; Scott, M; Stroberg, S R; Sullivan, C; Valdez, L; Walz, C; Weisshaar, D; Williams, S J; Wimmer, K

    2014-06-27

    The Gamow-Teller strength in the β(+) direction to (46)Sc was extracted via the (46)Ti(t,(3)He + γ) reaction at 115  MeV/u. The γ-ray coincidences served to precisely measure the very weak Gamow-Teller transition to a final state at 991 keV. Although this transition is weak, it is crucial for accurately estimating electron-capture rates in astrophysical scenarios with relatively low stellar densities and temperatures, such as presupernova stellar evolution. Shell-model calculations with different effective interactions in the pf shell-model space do not reproduce the experimental Gamow-Teller strengths, which is likely due to sd-shell admixtures. Calculations in the quasiparticle random phase approximation that are often used in astrophysical simulations also fail to reproduce the experimental Gamow-Teller strength distribution, leading to strongly overestimated electron-capture rates. Because reliable theoretical predictions of Gamow-Teller strengths are important for providing astrophysical electron-capture reaction rates for a broad set of nuclei in the lower pf shell, we conclude that further theoretical improvements are required to match astrophysical needs. PMID:25014806

  13. Dynamics of Soft Nanomaterials Captured by Transmission Electron Microscopy in Liquid Water

    PubMed Central

    Proetto, Maria T.; Rush, Anthony M.; Chien, Miao-Ping; Baeza, Patricia Abellan; Patterson, Joseph P.; Thompson, Matthew P.; Olson, Norman H.; Moore, Curtis E.; Rheingold, Arnold L.; Andolina, Christopher; Millstone, Jill; Howell, Stephen B.; Browning, Nigel D.; Evans, James E.; Gianneschi, Nathan C.

    2014-01-01

    In this paper we present in situ transmission electron microscopy (TEM) of synthetic polymeric nanoparticles with emphasis on capturing motion in a solvated, aqueous state. The nanoparticles studied were obtained from the direct polymerization of a Pt(II)-containing monomer. The resulting structures provided sufficient contrast for facile imaging in situ. We contend that this technique will quickly become essential in the characterization of analogous systems, especially where dynamics are of interest in the solvated state. We describe the preparation of the synthetic micellar nanoparticles together with their characterization and motion in liquid water with comparison to conventional electron microscopy analyses. PMID:24422495

  14. Introducing electron capture into the unitary-convolution-approximation energy-loss theory at low velocities

    SciTech Connect

    Schiwietz, G.; Grande, P. L.

    2011-11-15

    Recent developments in the theoretical treatment of electronic energy losses of bare and screened ions in gases are presented. Specifically, the unitary-convolution-approximation (UCA) stopping-power model has proven its strengths for the determination of nonequilibrium effects for light as well as heavy projectiles at intermediate to high projectile velocities. The focus of this contribution will be on the UCA and its extension to specific projectile energies far below 100 keV/u, by considering electron-capture contributions at charge-equilibrium conditions.

  15. Low-energy measurements of electron capture by multicharged ions from excited hydrogen atoms

    SciTech Connect

    Havener, C.C. ); Haque, M.A. ); Smith, A.C.H. ); Urbain, X. ); Zeijlmans van Emmichoven, P.A. Joint Institute for Heavy Ion Research, Holifield Heavy Ion Research Facility, Oak Ridge, Tennessee 37831-6374 )

    1993-06-05

    For very low collision energies electron capture from excited hydrogen by multicharged ions is characterized by enormous cross sections, the predicted maximum being comparable to the geometric size of the Rydberg atom. The ion-atom merged-beams technique is being used to study these collisions for the variety of charge states and the wide range of energies (0.1 to 1000 eV/amu) accessible to the apparatus. A neutral D beam containing a Rydberg atom population proportional to 1/n[sup 3] is produced by collisional electron detachment of 8 keV D[sup [minus

  16. Low-energy measurements of electron capture by multicharged ions from excited hydrogen atoms

    SciTech Connect

    Havener, C.C. ); Haque, M.A. ); Smith, A.C.H. ); Urbain, X. ); Zeijlmans van Emmichoven, P.A. Joint Inst. for Heavy Ion Research, Oak Ridge, TN (United Sta

    1992-01-01

    For very low collision energies electron capture from excited hydrogen by multicharged ions is characterized by enormous cross sections, the predicted maximum being comparable to the geometric size of the Rydberg atom. The ion-atom merged-beams technique is being used to study these collisions for the variety of charge states and the wide range of energies (0.1 to 1000 eV/amu) accessible to the apparatus. A neutral D beam containing a Rydberg atom population proportional to 1/n[sup 3] is produced by collisional electron detachment of 8 key D[sup [minus

  17. First measurements of electron temperature in the D region with a symmetric double probe

    NASA Technical Reports Server (NTRS)

    Szuszczewicz, E. P.

    1973-01-01

    Measurement of the altitude profile of electron temperature in the ionospheric D region with the aid of a symmetric double probe flown on a Nike-Cajun payload launched on Oct. 13, 1971. The procedure for determining the electron temperature from the parameters of the double probe's current-voltage characteristic under conditions of nonnegligible ion-atom collision frequencies is described. It is shown that in its first lower ionospheric application the technique of the symmetric double probe has yielded the lowest values of electron temperature yet measured and has provided the very first direct measurement of electron temperature in the D region.

  18. Observations of a Newly "Captured" Magnetosheath Field Line: Evidence for "Double Reconnection"

    NASA Technical Reports Server (NTRS)

    Chandler, Michael O.; Avanov, Levon A.; Craven, Paul D.; Mozer, Forrest S.; Moore, Thomas E.

    2007-01-01

    We have begun an investigation of the nature of the low-latitude boundary layer in the mid-altitude cusp region using data from the Polar spacecraft. This region has been routinely sampled for about three months each year for the periods 1999-2001 and 2004-2006. The low-to-mid-energy ion instruments frequently observed dense, magnetosheath-like plasma deep (in terms of distance from the magnetopause and in invariant latitude) in the magnetosphere. One such case, taken during a period of northward interplanetary magnetic field (IMF), shows magnetosheath ions within the magnetosphere with velocity distributions resulting from two separate merging sites along the same field lines. Cold ionospheric ions were also observed counterstreaming along the field lines, evidence that these field lines were closed. These results are consistent with the hypothesis that double merging can produce closed field .lines populated by solar wind plasma. Through the use of individual cases such as this and statistical studies of a broader database we seek to understand the morphology of the LLBL as it projects from the sub-solar region into the cusp. We will present preliminary results of our ongoing study.

  19. Neutron capture cross-section studies of Tellurium isotopes for neutrinoless double beta decay applications

    NASA Astrophysics Data System (ADS)

    Bhike, Megha; Tornow, Werner

    2014-09-01

    The CUORE detector at Gran Sasso, aimed at searching for neutrinoless double-beta decay of 130Te, employs an array of TeO2 bolometer modules. To understand and identify the contribution of muon and (α,n) induced neutrons to the CUORE background, fast neutron cature cross-section data of the tellurium isotopes 126Te, 128Te and 130Te have been measured with the activation method at eight different energies in the neutron energy range 0.5-7.5 MeV. Plastic pill boxes of diameter 1.6 cm and width 1 cm containing Te were irradiated with mono-energetic neutrons produced via the 3H(p,n)3He and 2H(d,n)3He reactions. The cross-sections were determined relative to the 197Au(n, γ)198Au and 115In(n,n')115m In standard cross sections. The activities of the products were measured using 60% lead-shielded HPGe detectors at TUNL's low background counting facility. The present results are compared with the evaluated data from TENDL-2012, ENDF/B-VII.1, JEFF-3.2 and JENDL-4.0, as well as with literature data.

  20. Investigation of ion capture in an electron beam ion trap charge-breeder for rare isotopes

    NASA Astrophysics Data System (ADS)

    Kittimanapun, Kritsada

    Charge breeding of rare isotope ions has become an important ingredient for providing reaccelerated rare isotope beams for science. At the National Superconducting Cyclotron Laboratory (NSCL), a reaccelerator, ReA, has been built that employs an advanced Electron Beam Ion Trap (EBIT) as a charge breeder. ReA will provide rare-isotope beams with energies of a few hundred keV/u up to tens of MeV/u to enable the study of properties of rare isotopes via low energy Coulomb excitation and transfer reactions, and to investigate nuclear reactions important for nuclear astrophysics. ReA consists of an EBIT charge breeder, a charge-over-mass selector, a room temperature radio-frequency quadrupole accelerator, and a superconducting radio-frequency linear accelerator. The EBIT charge breeder features a high-current electron gun, a long trap structure, and a hybrid superconducting magnet to reach both high acceptance for injected low-charge ions as well as high-electron beam current densities for fast charge breeding. In this work, continuous ion injection and capture in the EBIT have been investigated with a dedicated Monte-Carlo simulation code and in experimental studies. The Monte-Carlo code NEBIT considers the electron-impact ionization cross sections, space charge due to the electron beam current, ion dynamics, electric field from electrodes, and magnetic field from the superconducting magnet. Experiments were performed to study the capture efficiency as a function of injected ion beam current, electron beam current, trap size, and trap potential depth. The charge state evolution of trapped ions was studied, providing information about the effective current density of the electron beam inside the EBIT. An attempt was made to measure the effective space-charge potential of the electron beam by studying the dynamics of a beam injected and reflected inside the trap.

  1. Electron-nuclear double resonance on copper (II) tetraimidazole

    NASA Astrophysics Data System (ADS)

    Van Camp, Harlan L.; Sands, Richard H.; Fee, James A.

    1981-09-01

    We have investigated the electron-nuclear double resonance (ENDOR) from frozen aqueous solutions of 65Cu++(imidazole)4, 65Cu++ (imidazole-15N)4, and 65Cu++(imidazole-Dn)4, where n = 1, 2, 3, and 4 for selectively deuterated imidazole. We have observed ENDOR associated with the imidazole protons and the two imidazole nitrogens. The selective deuteration has allowed us to attempt identification of the weakly coupled protons responsible for the ENDOR spectrum, and a comparison of the overall line shape of that spectrum taken at two extreme points of the EPR spectrum suggests that some of the imidazole planes are tilted with respect to the plane of the complex. The ENDOR arising from the nitrogen nearest the copper is primarily isotropic with A(g⊥) = 41.6±1.5 MHz and A(g∥) = 39.8±1.5 MHz. The resonance shows little structure and seems consistent with a picture that requires some inequivalence among the various imidazoles. The remote nitrogen ENDOR reveals both hyperfine and quadrupole effects with approximately isotropic A(14N) = 1.79 MHz, Qz'z'?0.360 MHz, and Qx'x'y'x'?0.349 MHz. These values are in agreement with the results of the nuclear modulation effect [J. Chem. Phys. 69, 4921 (1978)]. The values for the quadrupole constants are thought to be accurate within 10% and are the same as are found in free imidazole. It is also demonstrated that, in this instance, ENDOR and the nuclear modulation effect are complementary in that they have each provided different parts of the same hyperfine spectrum.

  2. Identification and measurement of chlorinated organic pesticides in water by electron-capture gas chromatography

    USGS Publications Warehouse

    Lamar, William L.; Goerlitz, Donald F.; Law, LeRoy M.

    1965-01-01

    Pesticides, in minute quantities, may affect the regimen of streams, and because they may concentrate in sediments, aquatic organisms, and edible aquatic foods, their detection and their measurement in the parts-per-trillion range are considered essential. In 1964 the U.S. Geological Survey at Menlo Park, Calif., began research on methods for monitoring pesticides in water. Two systems were selected--electron-capture gas chromatography and microcoulometric-titration gas chromatography. Studies on these systems are now in progress. This report provides current information on the development and application of an electron-capture gas chromatographic procedure. This method is a convenient and extremely sensitive procedure for the detection and measurement of organic pesticides having high electron affinities, notably the chlorinated organic pesticides. The electron-affinity detector is extremely sensitive to these substances but it is not as sensitive to many other compounds. By this method, the chlorinated organic pesticide may be determined on a sample of convenient size in concentrations as low as the parts-per-trillion range. To insure greater accuracy in the identifications, the pesticides reported were separated and identified by their retention times on two different types of gas chromatographic columns.

  3. Electron Beam Analysis of Micrometeoroids Captured in Aerogel as Stardust Analogues

    NASA Technical Reports Server (NTRS)

    Graham, G. A.; Sheffield-Parker, J.; Bradley, P.; Kearsley, A. T.; Dai, Z. R.; Mayo, S. C.; Teslich, N.; Snead, C.; Westphal, A. J.; Ishii, H.

    2005-01-01

    In January 2004, NASA s Stardust spacecraft passed through the tail of Comet 81P/Wild-2. The on-board dust flux monitor instrument indicated that numerous micro- and nano-meter sized cometary dust particles were captured by the dedicated silica aerogel capture cell. The collected cometary particles will be returned to Earth in January 2006. Current Stardust analogues are: (i) Light-gas-gun accelerated individual mineral grains and carbonaceous meteoritic material in aerogels at the Stardust encounter velocity ca.approximately 6 kilometers per second. (ii) Aerogels exposed in low-Earth orbit (LEO) containing preserved cosmic dust grains. Studies of these impacts offer insight into the potential state of the captured cometary dust by Stardust and the suitability of various analytical techniques. A number of papers have discussed the application of sophisticated synchrotron analytical techniques to analyze Stardust particles. Yet much of the understanding gained on the composition and mineralogy of interplanetary dust particles (IDPs) has come from electron microscopy studies. Here we discuss the application of scanning electron microscopy (SEM) for Stardust during the preliminary phase of post-return investigations.

  4. N2O analysis in the atmosphere via electron capture-gas chromatography

    NASA Technical Reports Server (NTRS)

    Rasmussen, R. A.; Krasnec, J.; Pierotti, D.

    1976-01-01

    The potential of commercially available pulse-modulated electron capture detector (ECD)-equipped gas chromatographs for direct measurement of ambient levels of N2O is assessed. Since the sensitivity of ECD to N2O is directly proportional to the detector operating temperature and detector standing current, it is necessary to use a 'hot' ECD (250-350 C). The method is shown to be very precise with a standard error not exceeding 1% for automated analysis of ambient air samples. The technology is available to permit highly accurate routine direct analysis of N2O in the troposphere and stratosphere. Both captured air samples or direct real-time measurement from research vessels or airborne platforms are possible.

  5. High-energy two-electron capture with emission of a single photon

    SciTech Connect

    Drukarev, E. G.; Mikhailov, A. I.; Mikhailov, I. A.; Scheid, W.

    2007-12-15

    We investigate the two-electron capture with emission of a single photon to the ground state in the Coulomb field of a heavy nucleus in its collision with a light atom. Describing electron-electron interactions in the bound state perturbatively, we obtained an analytical formula for the high-energy limit of the cross section. In combination with previous results obtained in the same approach we calculated the cross section in a broad interval of energies of the collision. We show that the amplitude of the process at high energy depends on the behavior of the bound state wave function near the triple coalescence point. We analyze the properties of the approximate wave functions which are necessary for the description of the high-energy limit.

  6. Quantum fluctuations and coherence in high-precision single-electron capture.

    PubMed

    Kashcheyevs, Vyacheslavs; Timoshenko, Janis

    2012-11-21

    The phase of a single quantum state is undefined unless the history of its creation provides a reference point. Thus, quantum interference may seem hardly relevant for the design of deterministic single-electron sources which strive to isolate individual charge carriers quickly and completely. We provide a counterexample by analyzing the nonadiabatic separation of a localized quantum state from a Fermi sea due to a closing tunnel barrier. We identify the relevant energy scales and suggest ways to separate the contributions of quantum nonadiabatic excitation and back tunneling to the rare noncapture events. In the optimal regime of balanced decay and nonadiabaticity, our simple electron trap turns into a single-lead Landau-Zener back tunneling interferometer, revealing the dynamical phase accumulated between the particle capture and leakage. The predicted "quantum beats in back tunneling" may turn the error of a single-electron source into a valuable signal revealing essentially nonadiabatic energy scales of a dynamic quantum dot. PMID:23215606

  7. Fine-grid calculations for stellar electron and positron capture rates on Fe isotopes

    SciTech Connect

    Nabi, Jameel-Un; Tawfik, Abdel Nasser

    2013-03-15

    The acquisition of precise and reliable nuclear data is a prerequisite to success for stellar evolution and nucleosynthesis studies. Core-collapse simulators find it challenging to generate an explosion from the collapse of the core of massive stars. It is believed that a better understanding of the microphysics of core-collapse can lead to successful results. The weak interaction processes are able to trigger the collapse and control the lepton-to-baryon ratio (Y{sub e}) of the corematerial. It is suggested that the temporal variation of Y{sub e} within the core of a massive star has a pivotal role to play in the stellar evolution and a fine-tuning of this parameter at various stages of presupernova evolution is the key to generate an explosion. During the presupernova evolution of massive stars, isotopes of iron, mainly {sup 54-56}Fe, are considered to be key players in controlling Y{sub e} ratio via electron capture on these nuclides. Recently an improved microscopic calculation of weak-interaction-mediated rates for iron isotopes was introduced using the proton-neutron quasiparticle random-phase-approximation (pn-QRPA) theory. The pn-QRPA theory allows a microscopic state-by-state calculation of stellar capture rates which greatly increases the reliability of calculated rates. The results were suggestive of some fine-tuning of the Y{sub e} ratio during various phases of stellar evolution. Here we present for the first time the fine-grid calculation of the electron and positron capture rates on {sup 54-56}Fe. The sensitivity of the pn-QRPA calculated capture rates to the deformation parameter is also studied in this work. Core-collapse simulators may find this calculation suitable for interpolation purposes and for necessary incorporation in the stellar evolution codes.

  8. Electronic data capture and DICOM data management in multi-center clinical trials

    NASA Astrophysics Data System (ADS)

    Haak, Daniel; Page, Charles-E.; Deserno, Thomas M.

    2016-03-01

    Providing eligibility, efficacy and security evaluation by quantitative and qualitative disease findings, medical imaging has become increasingly important in clinical trials. Here, subject's data is today captured in electronic case reports forms (eCRFs), which are offered by electronic data capture (EDC) systems. However, integration of subject's medical image data into eCRFs is insufficiently supported. Neither integration of subject's digital imaging and communications in medicine (DICOM) data, nor communication with picture archiving and communication systems (PACS), is possible. This aggravates the workflow of the study personnel, in special regarding studies with distributed data capture in multiple sites. Hence, in this work, a system architecture is presented, which connects an EDC system, a PACS and a DICOM viewer via the web access to DICOM objects (WADO) protocol. The architecture is implemented using the open source tools OpenClinica, DCM4CHEE and Weasis. The eCRF forms the primary endpoint for the study personnel, where subject's image data is stored and retrieved. Background communication with the PACS is completely hidden for the users. Data privacy and consistency is ensured by automatic de-identification and re-labelling of DICOM data with context information (e.g. study and subject identifiers), respectively. The system is exemplarily demonstrated in a clinical trial, where computer tomography (CT) data is de-centrally captured from the subjects and centrally read by a chief radiologists to decide on inclusion of the subjects in the trial. Errors, latency and costs in the EDC workflow are reduced, while, a research database is implicitly built up in the background.

  9. Heterogeneous electron transfer at nanoscopic electrodes: importance of electronic structures and electric double layers.

    PubMed

    Chen, Shengli; Liu, Yuwen; Chen, Junxiang

    2014-08-01

    Heterogeneous electron-transfer (ET) processes at solid electrodes play key roles in molecular electronics and electrochemical energy conversion and sensing. Electrode nanosization and/or nanostructurization are among the major current strategies for performance promotion in these fields. Besides, nano-sized/structured electrodes offer great opportunities to characterize electrochemical structures and processes with high spatial and temporal resolution. This review presents recent insights into the nanoscopic size and structure effects of electrodes and electrode materials on heterogeneous ET kinetics, by emphasizing the importance of the electric double-layer (EDL) at the electrode/electrolyte interface and the electronic structure of electrode materials. It is shown, by general conceptual analysis and recent example demonstrations of representative electrode systems including electrodes of nanometer sizes and gaps and of nanomaterials such as sp(2) hybridized nanocarbons and semiconductor quantum dots, how the heterogeneous ET kinetics, the electronic structures of electrodes, the EDL structures at the electrode/electrolyte interface and the nanoscopic electrode sizes and structures may be related. PMID:24871071

  10. Electron capture into large-l Rydberg states of multiply charged ions escaping from solid surfaces

    NASA Astrophysics Data System (ADS)

    Nedeljković, N.; Nedeljković, Lj.; Mirković, M.

    2003-07-01

    We have investigated the electron capture into large-l Rydberg states of multiply charged ionic projectiles (e.g., the core charges Z=6, 7, and 8) escaping solid surfaces with intermediate velocities (v≈1 a.u.) in the normal emergence geometry. A model of the nonresonant electron capture from the solid conduction band into the moving large angular-momentum Rydberg states of the ions is developed through a generalization of our results obtained previously for the low-l cases (l=0, 1, and 2). The model is based on the two-wave-function dynamics of the Demkov-Ostrovskii type. The electron exchange process is described by a mixed flux through a moving plane (“Firsov plane”), placed between the solid surface and the ionic projectile. Due to low eccentricities of the large-l Rydberg systems, the mixed flux must be evaluated through the whole Firsov plane. It is for this purpose that a suitable asymptotic method is developed. For intermediate ionic velocities and for all relevant values of the principal quantum number n≈Z, the population probability Pnl is obtained as a nonlinear l distribution. The theoretical predictions concerning the ions S VI, Cl VII, and Ar VIII are compared with the available results of the beam-foil experiments.

  11. Capturing SCL and HR changes to win and loss events during gambling on electronic machines.

    PubMed

    Wilkes, Benjamin L; Gonsalvez, Craig J; Blaszczynski, Alex

    2010-12-01

    The role of physiological arousal is central to theories about the onset and maintenance of gambling behaviours including problem gambling. The range of possibilities suggested include tonic underarousal and phasic abnormalities such as hypersensitivity to reward and/or reduced sensitivity to negative consequences associated with losses. Among the various types of gambling, electronic gambling machines (EGMs) are associated with the large majority of gambling related problems. The demonstration that physiological changes associated with rapidly occurring win and loss events during electronic gambling can be reliably captured is fundamental to further progress in the psychophysiology of gambling. The current study monitored electrodermal and cardiac activities of twenty-four healthy participants to event outcomes (losses, fake wins, small wins and big wins) during a task on a real EGM. The results demonstrated that it is possible to reliably capture the profile of physiological changes as they occurred in real time to the many different win and loss events during electronic gambling. Relative to baseline levels, win events produced significant increases in skin conductance levels, (but not in HR) whereas loss events produced no significant changes. The study has important applications for further experimental and clinical research. PMID:20801172

  12. The gas-liquid chromatograph and the electron capture detection in equine drug testing.

    PubMed Central

    Blake, J. W.; Tobin, T.

    1976-01-01

    Three gas-liquid chromatographic (G.L.C.) procedures discussed have been designed around the four "esses" of detection tests--speed, sensitivity, simplicity, and specificity. These techniques are admirably applicable to the very low plasma drug levels encountered in blood testing under pre-race conditions. The methods are equally applicable to post-race testing procedures, where both blood and urine samples are tested. Drugs can only rarely be detected by the electron capture detector (E.C.D.) without a prior derivatization step, which conveys to the drug(s) high electron affinity. Because of broad applicability, two derivatizing agents, heptafluorobutyric (HFBA) and pentafluorpropionic (PFPA) anhydrides are employed. The three techniques, allowing broad coverage of various drug classes are: 1) direct derivatization of drugs to form strongly electron capturing amides and esters. 2) reductive fragmentation of drugs with lithium aluminum hydride to form alcohols, with conversion to ester derivatives. 3) oxidative fragmentation of drugs with potassium dichromate to form derivatizable groups, followed by direct derivatization. PMID:1000157

  13. Advantages of external accumulation for electron capture dissociation in Fourier transform mass spectrometry.

    PubMed

    Haselmann, K F; Budnik, B A; Olsen, J V; Nielsen, M L; Reis, C A; Clausen, H; Johnsen, A H; Zubarev, R A

    2001-07-01

    A combination of external accumulation (XA) with electron capture dissociation (ECD) improves the electron capture efficiency, shortens the analysis time, and allows for rapid integration of multiple scans in Fourier transform mass spectrometry. This improves the signal-to-noise ratio and increases the number of detected products, including structurally important MS3 fragments. With XA-ECD, the range of the labile species amenable to ECD is significantly extended. Examples include the first-time determination of the positions of six GalNAc groups in a 60-residue peptide, five sialic acid and six O-linked GalNAc groups in a 25-residue peptide, and the sulfate group position in a 11-residue peptide. Even weakly bound supramolecular aggregates, including nonspecific peptide complexes, can be analyzed with XA-ECD. Preliminary results are reported on high-rate XA-ECD that uses an indirectly heated dispenser cathode as an electron source. This shortens the irradiation time to > or = 1 ms and increases the acquisition rate to 3 scans/s, an improvement by a factor of 10-100. PMID:11467546

  14. The Sensitivity of Core-collapse Supernovae to Nuclear Electron Capture

    NASA Astrophysics Data System (ADS)

    Sullivan, Chris; O'Connor, Evan; Zegers, Remco G. T.; Grubb, Thomas; Austin, Sam M.

    2016-01-01

    A weak-rate library aimed at investigating the sensitivity of astrophysical environments to variations of electron-capture rates on medium-heavy nuclei has been developed. With this library, the sensitivity of the core-collapse and early post-bounce phases of core-collapse supernovae to nuclear electron capture is examined. The rates are adjusted by factors consistent with uncertainties indicated by comparing theoretical rates to those deduced from charge-exchange and β-decay measurements. To ensure a model-independent assessment, sensitivity studies across a comprehensive set of progenitors and equations of state are performed. We find a +16/-4% range in the mass of the inner core at shock formation and a ±20% range of peak {ν }e luminosity during the deleptonization burst. These ranges are five times as large as those seen from a separate progenitor study, where we evaluate the sensitivity of these parameters to 32 presupernova models. Additionally, the simulations are found to be more sensitive to a reduction in electron-capture rates than an enhancement, and specifically to the reduction in rates for neutron-rich nuclei near the N = 50 closed neutron shell. As measurements for medium-heavy (A> 65) and neutron-rich nuclei are sparse, and because accurate theoretical models that account for nuclear structure considerations of individual nuclei are not readily available, rates for these nuclei may be overestimated. If more accurate estimates confirm this, results from this study indicate that significant changes to the core-collapse trajectory are expected. For this reason, experimental and theoretical efforts should focus on this region of the nuclear chart.

  15. Electron Capture by a Hydrated Gaseous Peptide: Effects of Water on Fragmentation and Molecular Survival

    PubMed Central

    Prell, James S.; O'Brien, Jeremy T.; Holm, Anne I. S.; Leib, Ryan D.; Donald, William A.; Williams, Evan R.

    2008-01-01

    The effects of water on electron capture dissociation products, molecular survival, and recombination energy are investigated for diprotonated Lys-Tyr-Lys solvated by between zero and 25 water molecules. For peptide ions with between 12 and 25 water molecules attached, electron capture results in a narrow distribution of product ions corresponding to primarily the loss of 10-12 water molecules from the reduced precursor. From these data, the recombination energy (RE) is determined to be equal to the energy that is lost by evaporating on average 10.7 water molecules, or 4.3 eV. Because water stabilizes ions, this value is a lower limit to the RE of the unsolvated ion, but it indicates that the majority of the available RE is deposited into internal modes of the peptide ion. Plotting the fragment ion abundances for ions formed from precursors with fewer than 11 water molecules as a function of hydration extent results in an energy resolved breakdown curve from which the appearance energies of the b2+, y2+, z2+•, c2+, and (KYK + H)+ fragment ions formed from this peptide ion can be obtained; these values are 78, 88, 42, 11, and 9 kcal/mol, respectively. The propensity for H atom loss and ammonia loss from the precursor changes dramatically with the extent of hydration, and this change in reactivity can be directly attributed to a “caging” effect by the water molecules. These are the first experimental measurements of the RE and appearance energies of fragment ions due to electron capture dissociation of a multiply charged peptide. This novel ion nanocalorimetry technique can be applied more generally to other exothermic reactions that are not readily accessible to investigation by more conventional thermochemical methods. PMID:18761457

  16. Single electron capture measurements in collisions of K+ on N2

    NASA Astrophysics Data System (ADS)

    Alarcón, F. B.; Fuentes, B. E.; Martínez, H.; Yousif, F. B.

    2014-08-01

    Absolute total charge transfer cross sections have been measured for K+-N2 collisions, at impact energies between 1.0 and 3.5 keV. The charge transfer cross sections show a monotonic increasing behaviour as a function of the incident energy. Agreement with other groups is observed as the present measurements extend to lower energies. A semi-empirical calculation shows a similar behaviour to the present data with respect to the electron capture cross sections as a function of energy.

  17. Determination of fluoxetine and norfluoxetine in plasma by gas chromatography with electron-capture detection

    SciTech Connect

    Nash, J.F.; Bopp, R.J.; Carmichael, R.H.; Farid, K.Z.; Lemberger, L.

    1982-10-01

    This gas-chromatographic method for assay of fluoxetine and norfluoxetine in human plasma involves extraction of the drugs and use of a /sup 63/Ni electron-capture detector. The linear range of detection is 25 to 800 micrograms/L for each drug. Overall precision (CV) in the concentration range of 10 to 100 micrograms/L for both drugs was approximately 10%. Accuracy (relative error) in the same concentration range was approximately +10%. None of the commonly prescribed antidepressants or tranquilizers that we tested interfere with the assay.

  18. Neutrino signal of electron-capture supernovae from core collapse to cooling.

    PubMed

    Hüdepohl, L; Müller, B; Janka, H-T; Marek, A; Raffelt, G G

    2010-06-25

    An 8.8M{⊙} electron-capture supernova was simulated in spherical symmetry consistently from collapse through explosion to essentially complete deleptonization of the forming neutron star. The evolution time (∼9  s) is short because high-density effects suppress our neutrino opacities. After a short phase of accretion-enhanced luminosities (∼200  ms), luminosity equipartition among all species becomes almost perfect and the spectra of ν{e} and ν{μ,τ} very similar, ruling out the neutrino-driven wind as r-process site. We also discuss consequences for neutrino flavor oscillations. PMID:20867357

  19. Total single electron capture cross sections for collisions of multicharged ions with He atoms

    NASA Astrophysics Data System (ADS)

    Rahmanian, M.; Shojaei, F.; Fathi, R.

    2016-09-01

    The three-body boundary corrected Born distorted wave method is utilized to compute the total cross sections for single electron capture in the collisions of the fast ions ({{{H}}}1+, He{}2+, Li{}3+, {{{B}}}5+ and {{{C}}}6+) with helium targets in their ground states. Both post and prior forms of the transition amplitude are obtained in terms of two-dimensional integrals and the total cross sections are computed via three-dimensional numerical integrations. The present results show reasonable agreement with the measurements and three- and four-body theoretical computations, especially at higher incident energies.

  20. Neutrino Signal of Electron-Capture Supernovae from Core Collapse to Cooling

    SciTech Connect

    Huedepohl, L.; Mueller, B.; Janka, H.-T.; Marek, A.; Raffelt, G. G.

    2010-06-25

    An 8.8M{sub {center_dot}}electron-capture supernova was simulated in spherical symmetry consistently from collapse through explosion to essentially complete deleptonization of the forming neutron star. The evolution time ({approx}9 s) is short because high-density effects suppress our neutrino opacities. After a short phase of accretion-enhanced luminosities ({approx}200 ms), luminosity equipartition among all species becomes almost perfect and the spectra of {nu}{sub e} and {nu}{sub {mu},{tau}}very similar, ruling out the neutrino-driven wind as r-process site. We also discuss consequences for neutrino flavor oscillations.

  1. Site determination of radioactive atoms from the interference effect of electron-capture x rays

    SciTech Connect

    Sasaki, Y.C.; Suzuki, Y.; Tomioka, Y.; Ishibashi, T. ); Satoh, I.; Hirokawa, K. )

    1994-12-01

    We observed the interference effect of electron-capture x rays emitted by nuclear transformations in radioactive atoms. The interference fringes are generated between the direct monochromatic emissions from the radioactive atoms and the emissions totally reflected by the substrate surface. The site of a radioactive atom can be determined by analyzing the measured interference fringes because the period of these fringes depends on the position of the radioactive atoms relative to the substrate surface. A monolayer of [sup 51]Cr above a Pt substrate was used as a model sample.

  2. A Partnership Approach for Electronic Data Capture in Small-Scale Clinical Trials

    PubMed Central

    Franklin, Joshua D.; Guidry, Alicia; Brinkley, James F.

    2011-01-01

    Amid researchers’ growing need for study data management, the CTSA-funded Institute for Translational Health Sciences developed an approach to combine technical and scientific resources with small-scale clinical trials researchers in order to make Electronic Data Capture more efficient. In a 2-year qualitative evaluation we found that the importance of ease of use and training materials outweighed number of features and functionality. EDC systems we evaluated were Catalyst Web Tools, OpenClinica and REDCap. We also found that two other systems, Caisis and LabKey, did not meet the specific user needs of the study group. PMID:21651992

  3. Relativistic effects on giant resonances in electron-impact double ionization

    SciTech Connect

    Pindzola, M.S.

    1987-06-01

    The electron-impact double-ionization cross section for Fr/sup +/ is calculated in the distorted-wave Born approximation. A giant resonance in the 5d subshell ionization-autoionization contribution to the cross section is found to be quite sensitive to changes in the double-well potential caused by relativistic effects on bound-state wave functions.

  4. Measurement of the beta+ and orbital electron-capture decay rates in fully ionized, hydrogenlike, and heliumlike 140Pr ions.

    PubMed

    Litvinov, Yu A; Bosch, F; Geissel, H; Kurcewicz, J; Patyk, Z; Winckler, N; Batist, L; Beckert, K; Boutin, D; Brandau, C; Chen, L; Dimopoulou, C; Fabian, B; Faestermann, T; Fragner, A; Grigorenko, L; Haettner, E; Hess, S; Kienle, P; Knöbel, R; Kozhuharov, C; Litvinov, S A; Maier, L; Mazzocco, M; Montes, F; Münzenberg, G; Musumarra, A; Nociforo, C; Nolden, F; Pfützner, M; Plass, W R; Prochazka, A; Reda, R; Reuschl, R; Scheidenberger, C; Steck, M; Stöhlker, T; Torilov, S; Trassinelli, M; Sun, B; Weick, H; Winkler, M

    2007-12-31

    We report on the first measurement of the beta+ and orbital electron-capture decay rates of 140Pr nuclei with the simplest electron configurations: bare nuclei, hydrogenlike, and heliumlike ions. The measured electron-capture decay constant of hydrogenlike 140Pr58+ ions is about 50% larger than that of heliumlike 140Pr57+ ions. Moreover, 140Pr ions with one bound electron decay faster than neutral 140Pr0+ atoms with 59 electrons. To explain this peculiar observation one has to take into account the conservation of the total angular momentum, since only particular spin orientations of the nucleus and of the captured electron can contribute to the allowed decay. PMID:18233571

  5. Spin-Selective Transport of Electrons in DNA Double Helix

    NASA Astrophysics Data System (ADS)

    Guo, Ai-Min; Sun, Qing-feng

    2012-05-01

    The experiment that the high spin selectivity and the length-dependent spin polarization are observed in double-stranded DNA [Science 331, 894 (2011)SCIEAS0036-807510.1126/science.1199339], is elucidated by considering the combination of the spin-orbit coupling, the environment-induced dephasing, and the helical symmetry. We show that the spin polarization in double-stranded DNA is significant even in the case of weak spin-orbit coupling, while no spin polarization appears in single-stranded DNA. Furthermore, the underlying physical mechanism and the parameter dependence of the spin polarization are studied.

  6. Determination of nitrogen spin concentration in diamond using double electron-electron resonance

    NASA Astrophysics Data System (ADS)

    Stepanov, Viktor; Takahashi, Susumu

    2016-07-01

    Diamond has been extensively investigated recently due to a wide range of potential applications of nitrogen-vacancy (NV) defect centers existing in a diamond lattice. The applications include magnetometry and quantum information technologies, and long decoherence time (T2) of NV centers is critical for those applications. Although it has been known that T2 highly depends on the concentration of paramagnetic impurities in diamond, precise measurement of the impurity concentration remains challenging. In the present work we show a method to determine a wide range of the nitrogen concentration (n ) in diamond using a wide-band high-frequency electron spin resonance and double electron-electron resonance spectrometer. Moreover, we investigate T2 of the nitrogen impurities and show the relationship between T2 and n . The method developed here is applicable for various spin systems in solid and implementable in nanoscale magnetic resonance spectroscopy with NV centers to characterize the concentration of the paramagnetic spins within a microscopic volume.

  7. Wannier threshold theory for the description of the two-electron cusp in the ion-induced double ionization of atoms

    NASA Astrophysics Data System (ADS)

    Barrachina, R. O.; Gulyás, L.; Sarkadi, L.

    2016-02-01

    The double electron capture into the continuum states of the projectile (double ECC) is investigated theoretically in collisions of 100 keV He2+ ions with He atoms. The process is described within the framework of the impact parameter and frozen-correlation approximations where the single-electron events are treated by the continuum distorted wave method. On the other hand, the Wannier theory is employed for describing the angular correlation between both ejected electrons. This treatment substantially improved the agreement between the theory and experiment as compared to the previous version of the theory (Gulyás et al., 2010) in which the correlation between the ejected electrons was taken into account by the Coulomb density of states approximation.

  8. Differentiation of Norvaline and Valine in Peptides by Hot Electron Capture Dissociation.

    PubMed

    Yu, Xiang; Zhong, Wendy

    2016-06-01

    During the production of recombinant proteins, misincorporation of Nva (norvaline) is common and causes heterogeneity or even toxicity. To characterize Nva and differentiate it from Val (Valine), a systematic study was conducted using hot electron capture dissociation (HECD) and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. The thorough investigation of the fragmentation behaviors of a set of model peptides led us to reveal the characteristic/diagnostic fragment ions, w ions, which can be used to differentiate Val and Nva. However, when both Nva and Val were present in one peptide, the observation of interfering ions may mislead the interpretation. Interestingly, HECD also produced v ions, which have the same nominal mass as the M+1 isotope of the w ion and can only be determined by MS with ultrahigh mass resolution and high mass accuracy. The energy-dependent study of the v ion provided an unambiguous identification of Nva and Val since the v ion was generated only when Val was present, not Nva within the electron energy range we studied. In addition, an electron energy-dependent curve provided an overall picture on how w ions and v ions, as well as interfering ions, behaved as the electron energy increased from 1.5 to 14 eV. The results suggest that careful selection of electron energy during a HECD experiment is crucial for the unambiguous differentiation of Val and Nva. PMID:27153319

  9. Capturing structured, pulmonary disease-specific data elements in electronic health records.

    PubMed

    Gabriel, Peter E; Gronkiewicz, Cynthia; Diamond, Edward J; French, Kim D; Christodouleas, John

    2015-04-01

    Electronic health records (EHRs) have the potential to improve health-care quality by allowing providers to make better decisions at the point of care based on electronically aggregated data and by facilitating clinical research. These goals are easier to achieve when key, disease-specific clinical information is documented as structured data elements (SDEs) that computers can understand and process, rather than as free-text/natural-language narrative. This article reviews the benefits of capturing disease-specific SDEs. It highlights several design and implementation considerations, including the impact on efficiency and expressivity of clinical documentation and the importance of adhering to data standards when available. Pulmonary disease-specific examples of collection instruments are provided from two commonly used commercial EHRs. Future developments that can leverage SDEs to improve clinical quality and research are discussed. PMID:25846531

  10. Mechanism of 'GSI oscillations' in electron capture by highly charged hydrogen-like atomic ions

    SciTech Connect

    Krainov, V. P.

    2012-07-15

    We suggest a qualitative explanation of oscillations in electron capture decays of hydrogen-like {sup 140}Pr and {sup 142}Pm ions observed recently in an ion experimental storage ring (ESR) of Gesellschaft fuer Schwerionenforschung (GSI) mbH, Darmstadt, Germany. This explanation is based on the electron multiphoton Rabi oscillations between two Zeeman states of the hyperfine ground level with the total angular momentum F = 1/2. The Zeeman splitting is produced by a constant magnetic field in the ESR. Transitions between these states are produced by the second, sufficiently strong alternating magnetic field that approximates realistic fields in the GSI ESR. The Zeeman splitting amounts to only about 10{sup -5} eV. This allows explaining the observed quantum beats with the period 7 s.

  11. Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector

    PubMed Central

    Field, Christopher R.; Lubrano, Adam; Woytowitz, Morgan; Giordano, Braden C.; Rose-Pehrsson, Susan L.

    2014-01-01

    The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples. PMID:25145416

  12. Spin-resolved electron capture cross sections for C5+-H collisions

    NASA Astrophysics Data System (ADS)

    Li, X. Y.; Liu, L.; Wang, J. G.; Janev, R. K.

    2015-10-01

    The charge transfer process in C5+-H collisions has been theoretically studied using the two-center atomic orbital close-coupling method in the energy interval from 0.1 to 300 keV u-1. The interaction of active electron with the projectile ion is represented by model potentials different for the singlet and triplet systems of C4+(1snl) states. The results of the present calculations are compared with other theoretical results and experimental measurements and good agreement is obtained for the total spin-averaged cross sections in the overlapping energy range. For the spin-resolved cross sections, we found that the present total and n-shell electron capture cross sections are also in good agreement with the results of other theoretical studies in the overlapping energy range for both the singlet and triplet cases. Good overall agreement has been obtained with the results of other authors for the nl-state-selective cross sections, except for the capture to 3p and 4p singlet states at the low collision energies.

  13. Interstellar propagation and electron capture processes of galactic cosmic ray heavy ions in space

    NASA Technical Reports Server (NTRS)

    Miltra, B.; Biswas, S.; Goswami, J. N.

    1995-01-01

    The new information on galactic cosmic rays (GCR) derived from the Spacelab-3 cosmic ray experiment 'Anuradha' shows that at 25-125 MeV/N GCR sub-iron and iron (Z = 21-28) particles consists of a mixture of partially ionized and fully ionized ions. Computation of electron capture and loss cross sections in hydrogen in 1-50 MeV/N energy range are made for Fe, Cr, Ti and Ni. From these it is concluded that: (1) these GCR particles must have captured orbital electrons at energies of about 1-5 MeV/N and (2) these particles are then reaccelerated to 300-500 MeV/N most probably in interstellar medium by collision with SNR shock fronts. Some reacceleration may take place also in heliospheric boundary region. It is suggested that these observations of partially ionized GCR ions of about 100 MeV/N in Spacelab-3 provide a direct evidence of reacceleration of GCR.

  14. Mechanistic Study on Electron Capture Dissociation of the Oligosaccharide-Mg2+ Complex

    NASA Astrophysics Data System (ADS)

    Huang, Yiqun; Pu, Yi; Yu, Xiang; Costello, Catherine E.; Lin, Cheng

    2014-08-01

    Electron capture dissociation (ECD) has shown great potential in structural characterization of glycans. However, our current understanding of the glycan ECD process is inadequate for accurate interpretation of the complex glycan ECD spectra. Here, we present the first comprehensive theoretical investigation on the ECD fragmentation behavior of metal-adducted glycans, using the cellobiose-Mg2+ complex as the model system. Molecular dynamics simulation was carried out to determine the typical glycan-Mg2+ binding patterns and the lowest-energy conformer identified was used as the initial geometry for density functional theory-based theoretical modeling. It was found that the electron is preferentially captured by Mg2+ and the resultant Mg+• can abstract a hydroxyl group from the glycan moiety to form a carbon radical. Subsequent radical migration and α-cleavage(s) result in the formation of a variety of product ions. The proposed hydroxyl abstraction mechanism correlates well with the major features in the ECD spectrum of the Mg2+-adducted cellohexaose. The mechanism presented here also predicts the presence of secondary, radical-induced fragmentation pathways. These secondary fragment ions could be misinterpreted, leading to erroneous structural determination. The present study highlights an urgent need for continuing investigation of the glycan ECD mechanism, which is imperative for successful development of bioinformatics tools that can take advantage of the rich structural information provided by ECD of metal-adducted glycans.

  15. Search for Oscillation of the Electron-Capture Decay Probability of Pm-142

    SciTech Connect

    Vetter, Paul A; Vetter, Paul; Clark, Roderick; Dvorak, Jan; Freedman, Stuart; Gregorich, Kenneth; Jeppesen, Henrik; Mittelberger, Daniel; Wiedeking, Mathis

    2008-07-03

    We have searched for time modulation of the electron capture decay probability of 142Pm in an attempt to confirm a recent claim from a group at the Gesellschaft fur Schwerionenforschung (GSI). We produced 142Pm via the 124Sn(23Na, 5n)142Pm reaction at the Berkeley 88-Inch Cyclotron with a bombardment time short compared to the reported modulation period. Isotope selection by the Berkeley Gas-filled Separator is followed by implantation and a long period of monitoring the 142Nd K alpha x-rays from the daughter. The decay time spectrum of the x-rays is well-described by a simple exponential and the measured half-life of 40.68(53) seconds is consistent with the accepted value. We observed no oscillatory modulation at the proposed frequency at a level 31 times smaller than that reported by Litvinov (Phys. Lett. B 664 (2008) 162). A literature search for previous experiments that might have been sensitive to the reported modulation uncovered another example in 142Eu electron-capture decay. A reanalysis of the published data shows no oscillatory behavior.

  16. Low-energy electron capture by Ne2+ ions from H(D)

    NASA Astrophysics Data System (ADS)

    Seredyuk, B.; Bruhns, H.; Savin, D. W.; Seely, D.; Aliabadi, H.; Galutschek, E.; Havener, C. C.

    2007-05-01

    Using the Oak Ridge National Laboratory (ORNL) ion-atom merged-beams apparatus, the absolute, total single-electron-capture cross section has been measured for collisions of Ne2+ with deuterium (D) at center-of-mass (c.m.) collision energies of 59-949eV/u . With the high-velocity ion beams now available at the ORNL Multicharged Ion Research Facility, we have extended our previous merged-beams measurement to lower c.m. collision energies. The data are compared to all four previously published measurements for Ne2++H(D) which differ considerably from one another at energies ≲600eV/u . We are unaware of any published theoretical cross-section data for Ne2++H(D) at the energies studied. Early quantal rate coefficient calculations for Ne2++H at eV/u energies suggest a cross section many orders of magnitude below previous measurements of the cross section at 40eV/u which is the lowest collision energy for which experimental results have been published. Here we compare our measurements to recent theoretical electron-capture results for He2++H . Both the experimental and theoretical results show a decreasing cross section with decreasing energy.

  17. Atmospheric measurements of carbonyl sulfide, dimethyl sulfide, and carbon disulfide using the electron capture sulfur detector

    NASA Technical Reports Server (NTRS)

    Johnson, James E.; Bates, Timothy S.

    1993-01-01

    Measurements of atmospheric dimethyl sulfide (DMS), carbonyl sulfide (COS), and carbon disulfide (CS2) were conducted over the Atlantic Ocean on board the NASA Electra aircraft during the Chemical Instrumentation Test and Evaluation (CITE 3) project using the electron capture sulfur detector (ECD-S). The system employed cryogenic preconcentration of air samples, gas chromatographic separation, catalytic fluorination, and electron capture detection. Samples collected for DMS analysis were scrubbed of oxidants with NaOH impregnated glass fiber filters to preconcentration. The detection limits (DL) of the system for COS, DMS, and CS2 were 5, 5, and 2 ppt, respectively. COS concentrations ranged from 404 to 603 ppt with a mean of 489 ppt for measurements over the North Atlantic Ocean (31 deg N to 41 deg N), and from 395 to 437 ppt with a mean of 419 ppt for measurements over the Tropical Atlantic Ocean (11 deg S to 2 deg N). DMS concentrations in the lower marine boundary layer, below 600-m altitude, ranged from below DL to 150 ppt from flights over the North Atlantic, and from 9 to 104 ppt over the Tropical Atlantic. CS2 concentrations ranged from below DL to 29 ppt over the North Atlantic. Almost all CS2 measurements over the Tropical Atlantic were below DL.

  18. Electron correlations in single-electron capture into any state of fast projectiles from heliumlike atomic systems

    NASA Astrophysics Data System (ADS)

    Mančev, Ivan; Milojević, Nenad; Belkić, Dževad

    2013-11-01

    State-selective and total single-electron capture cross sections in fast collisions of a bare projectile with a heliumlike target are examined in the four-body formalism. A special emphasis is given to a proper inclusion of dynamic electron-electron correlation effects. For this purpose, the post form of the four-body boundary-corrected first Born approximation (CB1-4B) is utilized. With regard to our related previous study, where the prior version has been considered, in the present work an extensive analytical study of the post-transition amplitude for electron capture into the arbitrary final states nflfmf of the projectile is carried out. The post-transition amplitude for single charge exchange encompassing symmetric and asymmetric collisions is derived in terms of five-dimensional integrals over real variables. The dielectronic interaction V12=1/r12≡1/|r⃗1-r⃗2| explicitly appears in the perturbation potential Vf of the post-transition probability amplitude Tif+, such that the CB1-4B method can provide information about the relative significance of the dynamic interelectron correlation in the collisions under study. An illustrative computation is performed involving state-selective and total single capture cross sections for the p-He collisions at intermediate and high impact energies. The so-called post-prior discrepancy, which plagues almost all the existing distorted wave approximations, is presently shown to be practically nonexistent in the CB1-4B method. The validity of our findings is critically assessed in comparisons with the available experimental data for both state-selective and total cross sections summed over all the discrete energy levels of the hydrogenlike atom formed with the projectile. Overall, excellent performance of the CB1-4B method is recorded, thus robustly establishing this formalism as the leading first-order description of high-energy single charge exchange, which is a collision of paramount theoretical and practical

  19. Acoustic double layer structures in dense magnetized electron-positron-ion plasmas

    SciTech Connect

    Akhtar, N.; Mahmood, S.

    2011-11-15

    The acoustic double layer structures are studied using quantum hydrodynamic model in dense magnetized electron-positron-ion plasmas. The extended Korteweg-de Vries is derived using reductive perturbation method. It is found that increase in the ion concentration in dense magnetized electron-positron plasmas increases the amplitude as well as the steepness of the double layer structure. However, increase in the magnetic field strength and decrease in the obliqueness of the nonlinear acoustic wave enhances only the steepness of the double layer structures. The numerical results have also been shown by using the data of the outer layer regions of white dwarfs given in the literature.

  20. State-resolved three-dimensional electron-momentum correlation in nonsequential double ionization of benzene

    NASA Astrophysics Data System (ADS)

    Winney, Alexander H.; Lin, Yun Fei; Lee, Suk Kyoung; Adhikari, Pradip; Li, Wen

    2016-03-01

    We report state-resolved electron-momentum correlation measurement of strong-field nonsequential double ionization in benzene. With a novel coincidence detection apparatus, highly efficient triple coincidence (electron-electron dication) and quadruple coincidence (electron-electron-cation-cation) are used to resolve the final ionic states and to characterize three-dimensional (3D) electron-momentum correlation. The primary states associated with dissociative and nondissociative dications are assigned. A 3D momentum anticorrelation is observed for the electrons in coincidence with dissociative benzene dication states whereas such a correlation is absent for nondissociative dication states.

  1. Electron dynamics of molecular double ionization by circularly polarized laser pulses

    SciTech Connect

    Tong, Aihong; Zhou, Yueming; Huang, Cheng; Lu, Peixiang

    2013-08-21

    Using the classical ensemble method, we have investigated double ionization (DI) of diatomic molecules driven by circularly polarized laser pulses with different internuclear distances (R). The results show that the DI mechanism changes from sequential double ionization (SDI) to nonsequential double ionization (NSDI) as the internuclear distance increases. In SDI range, the structure of the electron momentum distribution changes seriously as R increases, which indicates the sensitive dependence of the release times of the two electrons on R. For NSDI, because of the circular polarization, the ionization of the second electron is not through the well-known recollision process but through a process where the first electron ionizes over the inner potential barrier of the molecule, moves directly towards the other nucleus, and kicks out the second electron.

  2. Measuring the axial form factor of {sup 3}He using weak capture of polarized electrons

    SciTech Connect

    Dutta, D.

    2013-11-07

    A low energy, high intensity polarized electron beam could enable the extraction of the A=3 weak axial form factors F{sub A} using the reaction →e+{sup 3}He→{sup 3}H+ν. These form factors have never been measured before. We discuss the feasibility of such an experiment using a small toroidal magnet and a radial low energy recoil detector to tag the recoil tritons. A moderately high intensity polarized electron beam (>500 μA) with beam energies between 50 - 150 MeV is necessary for the cross section measurement and to provides a free clean measurement of the background. Moreover, in addition to the cross section, by measuring the electron spin and recoil triton correlation coefficient it may be possible to search for second class currents and to extract the ratio of the axial to the vector form factor of the nucleon. Such novel electron scattering based measurements would have a completely different set of systematic uncertainties compared to polarized neutron beta decay, neutrino scattering and muon capture experiments which are typically used to extract the weak form-factors.

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

    NASA Astrophysics Data System (ADS)

    Zhu, Lin

    1995-01-01

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

  4. CO₂ sorbents with scaffold-like Ca-Al layered double hydroxides as precursors for CO₂ capture at high temperatures.

    PubMed

    Chang, Po-Hsueh; Lee, Tai-Jung; Chang, Yen-Po; Chen, San-Yuan

    2013-06-01

    A highly stable high-temperature CO₂ sorbent consisting of scaffold-like Ca-rich oxides (Ca-Al-O) with rapid absorption kinetics and a high capacity is described. The Ca-rich oxides were prepared by annealing Ca-Al-NO₃ layered double hydroxide (LDH) precursors through a sol-gel process with Al(O(i)P)₃ and Ca(NO₃)₂ with Ca(2+)/Al(3+) ratios of 1:1, 2:1, 4:1, and 7:1. XRD indicated that only LDH powders were formed for Ca(2+)/Al(3+) ratios of 2:1. However, both LDH and Ca(OH)₂ phases were produced at higher ratios. Both TEM and SEM observations indicated that the Ca-Al-NO₃ LDHs displayed a scaffold-like porous structure morphology rather than platelet-like particles. Upon annealing at 600 °C, a highly stable porous network structure of the CaO-based Ca-Al-O mixed oxide (CAMO), composed of CaO and Ca₁₂Al₁₄O₃₃, was still present. The CAMO exhibited high specific surface areas (up to 191 m(2)g(-1)) and a pore size distribution of 3-6 nm, which allowed rapid diffusion of CO₂ into the interior of the material, inducing fast carbonation/calcination and enhancing the sintering-resistant nature over multiple carbonation/calcination cycles for CO₂ absorption at 700 °C. Thermogravimetric analysis results indicated that a CO₂ capture capacity of approximately 49 wt% could be obtained with rapid absorption from the porous 7:1 CAMO sorbents by carbonation at 700 °C for 5 min. Also, 94-98% of the initial CO₂ capture capability was retained after 50 cycles of multiple carbonation/calcination tests. Therefore, the CAMO framework is a good isolator for preventing the aggregation of CaO particles, and it is suitable for long-term cyclic operation in high-temperature environments. PMID:23650194

  5. Probing flexibility in porphyrin-based molecular wires using double electron electron resonance.

    PubMed

    Lovett, Janet E; Hoffmann, Markus; Cnossen, Arjen; Shutter, Alexander T J; Hogben, Hannah J; Warren, John E; Pascu, Sofia I; Kay, Christopher W M; Timmel, Christiane R; Anderson, Harry L

    2009-09-30

    A series of butadiyne-linked zinc porphyrin oligomers, with one, two, three, and four porphyrin units and lengths of up to 75 A, have been spin-labeled at both ends with stable nitroxide TEMPO radicals. The pulsed EPR technique of double electron electron resonance (DEER) was used to probe the distribution of intramolecular end-to-end distances, under a range of conditions. DEER measurements were carried out at 50 K in two types of dilute solution glasses: deutero-toluene (with 10% deutero-pyridine) and deutero-o-terphenyl (with 5% 4-benzyl pyridine). The complexes of the porphyrin oligomers with monodentate ligands (pyridine or 4-benzyl pyridine) principally adopt linear conformations. Nonlinear conformations are less populated in the lower glass-transition temperature solvent. When the oligomers bind star-shaped multidentate ligands, they are forced to bend into nonlinear geometries, and the experimental end-to-end distances for these complexes match those from molecular mechanics calculations. Our results show that porphyrin-based molecular wires are shape-persistent, and yet that their shapes can deformed by binding to multivalent ligands. Self-assembled ladder-shaped 2:2 complexes were also investigated to illustrate the scope of DEER measurements for providing structural information on synthetic noncovalent nanostructures. PMID:19736940

  6. Dynamic Phase Shifts in Nanoscale Distance Measurements by Double Electron Electron Resonance (DEER)†

    SciTech Connect

    Bowman, Michael K.; Maryasov, Alexander G.

    2007-04-01

    The off-resonant pump pulse used in double electron electron resonance (DEER) measurements produces dynamic phase shifts that are explained here by simple analytic and vector descriptions of the full range of signal behaviors observed during DEER measurements, including: large phase shifts in the signal; changes in the position and shape of the detected echo; and changes in the signal intensity. The dynamic phase shifts depend on the width, amplitude and offset frequency of the pump pulse. Isolated radicals as well as pairs or clusters of dipolar-coupled radicals have the same dynamic phase shift that is independent of pump pulse delay in a typical measurement. A method of calibrating both the pump pulse offset frequency and the pump pulse field strength is outlined. A vector model is presented that explains the dynamic phase shifts in terms of precessing magnetization that is either spin locked or precessing about the effective pump field during the pump pulse. Implications of the dynamic phase shifts are discussed as they relate to setting up, calibrating and interpreting the results of DEER measurements.

  7. Electron capture strength on odd- A nucleus 59Co in explosive astrophysical environment

    NASA Astrophysics Data System (ADS)

    Rahman, Muneeb-Ur; Nabi, Jameel-Un

    2014-05-01

    The Gamow-Teller (GT) transitions within massive stars play sumptuous role in the dynamics of core collapse supernovae. GT strength distributions and electron capture rates have been calculated for odd- A nucleus 59Co within the proton-neutron quasiparticles random phase approximation (pn-QRPA) formalism. The pn-QRPA results are compared with other model calculations and ( n, p) reaction experiment carried out at TRIUMF charge-exchange facility. The pn-QRPA calculated a total B( GT +) strength of 3.3 for 59Co to be compared with the shell model value of 2.5 and the 1.9±0.1 in the ( n, p) charge-exchange reaction. Aufderheide et al. (1993) extracted total strength equaling 2.4±0.3. The placement of GT centroid at 5.6 MeV by the pn-QRPA model is in reasonable agreement with the shell model centroid at 5.1 MeV whereas the measured GT centroid was placed at 4.4±0.3 MeV in the ( n, p) experiment. Fuller, Fowler and Newman (FFN) (1980, 1982a, 1982b), placed the GT centroid at too low excitation energy of 2.0 MeV in the daughter nucleus 59Fe, and this misplacement led to the enhancement of FFN rates. The suppressed pn-QRPA and shell model electron capture rates are in good agreement with each other. The rates are suggestive of higher value of Y e (electron-to-baryon ratio) and may contribute to a more massive homologously collapsing core resulting in a more energetic shock. It might be interesting for the simulators to check the effect of these suppressed rates on the fine-tuning of the time rate of Y e , the concomitant heavy element nucleosynthesis, and, on the energetics of the subsequent shock wave.

  8. Independent-electron analysis of the x-ray spectra from single-electron capture in Ne10 + collisions with He, Ne, and Ar atoms

    NASA Astrophysics Data System (ADS)

    Leung, Anthony C. K.; Kirchner, Tom

    2015-09-01

    We present a theoretical study on the x-ray spectra from single-electron capture in 4.54 keV/amu Ne10 +-He, -Ne, and -Ar collisions. Single-particle capture probabilities were calculated using the two-center basis generator method within the independent electron model. In this framework we investigated the effects of a time-dependent screening potential that models target response on capture cross sections and x-ray spectra. Excellent agreement is shown with the previously measured relative cross sections and x-ray spectra and calculations based on the classical trajectory Monte Carlo method using the no-response single-particle electron capture probabilities in a multinomial single-electron capture analysis. Our results demonstrate the importance of using this consistent statistical analysis of single-electron capture within the independent electron model; a requirement that a previous calculation for the same collision problem using the two-center atomic-orbital close-coupling method may not have considered.

  9. Suppression of ghost distances in multiple-spin double electron-electron resonance.

    PubMed

    von Hagens, Tona; Polyhach, Yevhen; Sajid, Muhammad; Godt, Adelheid; Jeschke, Gunnar

    2013-04-28

    Distance measurements by pulse electron paramagnetic resonance techniques are increasingly applied to multiple-spin systems. In the double electron-electron resonance experiment, more than two dipolar coupled spins manifest in an increased total modulation depth and in sum and difference dipolar frequency contributions that give rise to additional peaks appearing in the distance distribution, which do not correspond to the real interspin distances of the system and are hence referred to as ghost contributions. These ghost contributions may be so prominent that they might be mistaken for real distance peaks or that real distance peaks shift their position or disappear. We present a simple approximate procedure to suppress ghost distances to a great extent by manipulating the experimentally obtained form factor during data analysis by a simple power scaling with a scaling exponent ζ(N) = 1/(1-N), with N being the number of coupled spins in the system. This approach requires neither further experimental effort nor exact knowledge about labelling and inversion efficiency. This should enable routine application to biological systems. The approach is validated on simulated test cases for up to five spins and applied to synthetic model samples. The suppression of ghost distances with the presented approach works best for symmetric geometries and rigid molecules which, at the same time, are the cases where ghost contributions are most disturbing. The distance distributions obtained by power scaling are consistent with distributions that were obtained with previously obtained alternative approaches and agree, in some cases, strikingly well with the expectations for the true interspin distance distributions. PMID:23487036

  10. Searching for Experimental Verification of the Oscillation of Electron Capture Decay Probability

    NASA Astrophysics Data System (ADS)

    Vetter, Paul

    2009-05-01

    A group from Gesellschaft f"ur Schwerionenforschung (GSI) last year published an observation of time oscillations of the electron capture decay rate of stored hydrogen-like ions of ^142Pm and ^140Pr.(Phys. Lett. B 664, 162 (2008)). They proposed that the oscillating decay rate was caused by interference between momentum states of the ion caused by neutrino mass and flavor mixing. This hypothesis has been controversial, with several authors arguing either that neutrino mixing can or cannot be responsible. If neutrino mixing is responsible for the decay rate oscillations, then it should be possible to detect these oscillations in a simpler experiment without using stored hydrogenic ions, by observing an electron capture decay rate with an appropriate experiment time structure. If this were possible, it could revolutionize the study of neutrino mixing by allowing much simpler experiments to make precise measurements of mass differences and mixing angles. At LBNL, we performed an experiment to search for oscillations in electron capture rate using ^142Pm produced with a time short compared to the oscillation period, and counting ^142Nd Kα x-rays from the daughter. The decay time spectrum is well-described by a simple exponential, and we observed no statistically significant decay rate oscillations at a level much lower than proposed. A literature search for previous experiments that might have been sensitive to the reported modulation uncovered a candidate in ^142Eu. A reanalysis of that published data shows no decay rate oscillation. A recent experiment at Munich also did not observe decay rate oscillations in decays of ^180Re. Other potential explanations for the GSI decay oscillation data have been proposed, including quantum beats by nearly degenerate initial parent ion states and Thomas precession in the stored ions. I will discuss the status of experimental results, and possibilities for experimental confirmation of the various models. This work was supported by

  11. Charge-exchange reactions and electron-capture rates for presupernova stellar evolution

    NASA Astrophysics Data System (ADS)

    Zegers, Remco

    2015-04-01

    Weak reaction rates such as electron captures and beta decays play major roles in a variety of astrophysical phenomena, such as core-collapse and thermonuclear supernovae and accreting neutron stars. Consequently, the use of accurate weak reaction rates in astrophysical simulations to understand these phenomena is important. Unfortunately, the number of relevant nuclei is typically very large, and, except for a few special cases, it is impossible to rely on experimental results only: theoretical models must be used to estimate the weak reaction rates. These models can then be benchmarked and improved on the basis of a limited number of experimental data. The most important nuclear structure input that is required for calculating weak reaction rates are Gamow-Teller transition strengths. Although these can be extracted from beta and electron-capture decay data, the energy window accessible by such experiments is limited, if accessible at all. However, at the high temperatures and densities that occur in massive stars prior to the cataclysmic demise, transitions to final states at high excitation energies are important. In addition, to properly test theory, full Gamow-Teller transition strength distributions are very valuable. Fortunately, nature is kind: charge-exchange experiments at intermediate energies can provide the relevant strength distributions over a wide energy window and a variety of charge-exchange probes, such as (p,n), (n,p), (d,2 He) and (t,3 He) have been used to extract strengths of relevance for astrophysics (and for other purposes). This presentation will focus on efforts to validate electron capture rates calculated based on nuclear structure models for nuclei with masses ranging from A ~ 40-65, and on studies aimed at testing astrophysical sensitivities to uncertainties/deviations in the theoretical rates. These efforts include experiments with unstable isotopes, and special gamma-ray coincidence techniques to localize very weak, but

  12. Unipolar Complementary Circuits Using Double Electron Layer Tunneling Tansistors

    SciTech Connect

    Blount, M.A.; Hafich, M.J.; Moon, J.S.; Reno, J.L.; Simmons, J.A.

    1998-10-19

    We demonstrate unipolar complementary circuits consisting of a pair of resonant tunneling transistors based on the gate control of 2D-2D interlayer tunneling, where a single transistor - in addition to exhibiting a welldefined negative-differential-resistance can be operated with either positive or negative transconductance. Details of the device operation are analyzed in terms of the quantum capacitance effect and band-bending in a double quantum well structure, and show good agreement with experiment. Application of resonant tunneling complementary logic is discussed by demonstrating complementary static random access memory using two devices connected in series.

  13. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    PubMed Central

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; Li, F.; Pai, C.-H.; Wan, Y.; Wu, Y. P.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; Lu, W.

    2016-01-01

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method. PMID:27403561

  14. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    DOE PAGESBeta

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; Li, F.; Pai, C. -H.; Wan, Y.; Wu, Y. P.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; et al

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of themore » wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. As a result, the capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.« less

  15. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe.

    PubMed

    Zhang, C J; Hua, J F; Xu, X L; Li, F; Pai, C-H; Wan, Y; Wu, Y P; Gu, Y Q; Mori, W B; Joshi, C; Lu, W

    2016-01-01

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method. PMID:27403561

  16. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    NASA Astrophysics Data System (ADS)

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; Li, F.; Pai, C.-H.; Wan, Y.; Wu, Y. P.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; Lu, W.

    2016-07-01

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.

  17. Electron capture by Ne{sup 4+} ions from atomic hydrogen

    SciTech Connect

    Havener, C.C.; Rejoub, R.; Vane, C.R.; Krause, H.F.; Savin, D.W.; Schnell, M.; Wang, J.G.; Stancil, P.C.

    2005-03-01

    Using the Oak Ridge National Laboratory ion-atom merged-beams apparatus, the absolute total electron-capture cross section has been measured for collisions of Ne{sup 4+} with hydrogen and deuterium at relative energies in the center-of-mass frame between 0.10 and 1006 eV/u. Comparison with previous measurements shows large discrepancies between 80 and 600 eV/u. For energies below {approx}1 eV/u, a sharply increasing cross section is attributed to the ion-induced dipole attraction between the reactants. Multichannel Landau-Zener calculations are performed between 0.01 and 5000 eV/u and compare well to the measured total cross sections. Below {approx}5 eV/u, the present total cross section calculations show a significant target isotope effect. At 0.01 eV/u, the H:D total cross section ratio is predicted to be {approx}1.4 where capture is dominated by transitions into the Ne{sup 3+} (2s{sup 2}2p{sup 2}3d) configuration.

  18. Double electron ionization in Compton scattering of high energy photons by helium atoms

    SciTech Connect

    Amusia, M.Y.; Mikhailov, A.I.

    1995-08-01

    The cross section for double-electron ionization of two-electron atoms and ions in Compton scattering of high energy photons is calculated. It is demonstrated that its dependence on the incoming photon frequency is the same as that for single-electron ionization. The ratio of {open_quotes}double-to-single{close_quotes} ionization in Compton scattering was found to be energy independent and almost identical with the corresponding value for photoionization. For the He atom it is 1.68%. This surprising result deserves experimental verification.

  19. Large amplitude double layers in a positively charged dusty plasma with nonthermal electrons

    SciTech Connect

    Djebli, M.; Marif, H.

    2009-06-15

    A pseudopotential approach is used to investigate large amplitude dust-acoustic solitary structures for a plasma composed of positively charged dust, cold electrons, and nonthermal hot electrons. Numerical investigation for an adiabatic situation is conducted to examine the existence region of the wave. The negative potential of the double layers is found to be dependent on nonthermal parameters, Mach number, and electrons temperature. A range of the nonthermal parameters values exists for which two possible double layers for the same plasma mix at different Mach numbers and with significant different amplitudes. The present model is used to investigate localized structures in the lower-altitude Earth's ionosphere.

  20. Double electron excitation in He ions interacting with an aluminum surface

    NASA Astrophysics Data System (ADS)

    Riccardi, P.; Sindona, A.; Dukes, C. A.

    2016-04-01

    Observation of Auger electron emission from Al under the impact of He ions, at energies below the excitation threshold of Al-Al collisions, gives evidence for charge transfer in He-Al collisions. Excitation of 2 p -shell electrons in Al is produced by vacancy transfer, following double excitation of He by promotion of its 1 s level. Studies of ion scattering from surfaces currently neglect the double excitation of He. We discuss implications on the debate about electronic excitations and energy deposition, which is relevant to many fields, since helium ions are applied in the characterization and imaging of materials.

  1. Ultra-low Energy Calibration of LUX detector using 127Xe Electron Capture

    NASA Astrophysics Data System (ADS)

    Huang, Dongqing; Large Underground Xenon (LUX) Collaboration

    2015-04-01

    The LUX dark matter search experiment is a 350 kg two-phase liquid/gas xenon time projection chamber located at the 4850 ft level of the Sanford Underground Research Facility in Lead, SD. We present an absolute calibration of the liquid xenon electron recoil (ER) charge yield and fluctuations over an energy range 190 eVee to 33.2 keVee using low energy 127 Xe electron capture decay events from the LUX 85-day first WIMP search dataset. The sequence of gamma and X-ray cascade associated with 127 I produce clearly identified 2-vertex events in the LUX detector. We observe the K (33.2 keVee), L (5.2 keVee), M (1.1 keVee), and N (190 eVee) shell cascade events and verifiy the relative ratio of observed events for each shell. We extract both the mean and sigma of the charge signal yields (Qy) associated with the K, L, M, and N shell events. The N shell cascade analysis includes single extracted electron events, and represents the lowest energy ER in-situ measurements that have been explored in Xe.

  2. Fragmentation of peptide negative molecular ions induced by resonance electron capture

    PubMed Central

    Vasil’ev, Yury V.; Figard, Benjamin J.; Morré, Jeff; Deinzer, Max L.

    2009-01-01

    A simple robust method to study resonance gas-phase reactions between neutral peptides of low volatility and free electrons has been designed and implemented. Resonance electron capture (REC) experiments were performed by several neutral model peptides and two naturally occurring peptides. The assignment of negative ions (NIs) formed in these gas-phase reactions was based on high mass-resolving power experiments. From these accurate mass measurements, it was concluded that fragment NIs formed by low (1–2 eV) energy REC are of the same types as those observed in electron capture∕transfer dissociation, where the positive charge is a factor. The main feature resulting from these REC experiments by peptides is the occurrence of zn−1 ions, which are invariably of the highest abundances in the negative ion mass spectra of larger peptides. [M–H]− NIs presumably the carboxylate anion structure dominate the REC spectra of smaller peptides. There was no evidence for the occurrence of the complementary reaction, i.e., the formations of cn+1 ions. Instead, cn ions arose without hydrogen∕proton transfer albeit with lower abundances than that observed for zn−1 ions. Only the amide forms of small peptides showed more abundant ion peaks for the cn ions than for the zn−1 ions. The mechanisms for the N–Cα bond cleavage are discussed. PMID:19655877

  3. Rapid electron capture dissociation of mass-selectively accumulated oligodeoxynucleotide dications

    NASA Astrophysics Data System (ADS)

    Schultz, Kristin N.; Håkansson, Kristina

    2004-05-01

    We have performed extended characterization of the fragmentation patterns of oligodeoxynucleotide dications following electron capture dissociation (ECD) utilizing improved instrumentation. Our current results from a 9.4 T Fourier transform ion cyclotron resonance mass spectrometer equipped with mass-selective external ion accumulation and an indirectly heated dispenser cathode electron source demonstrate much richer fragmentation than from a previous 7 T instrument with a directly heated filament electron source. We propose the previous absence of backbone product ions from purine-containing oligonucleotides is a result of intramolecular hydrogen bonding, preventing product ions from separating. Similar behavior is observed at non-optimized ECD conditions with the current instrumentation. However, infrared laser heating of the resulting charge-reduced radical species results in extensive backbone fragmentation (different from infrared multiphoton dissociation) of the oligonucleotide dA6, demonstrating potential for ECD to characterize nucleic acid secondary structure. Under more optimized conditions, rich fragmentation, mostly in terms of w, (a/z-B), and (c/x-B) products, is observed for dA6, dC6, dG5, and d(GCATGC) following ECD only, allowing complete sequencing in several cases. The current ECD spectra contain some doubly charged products, indicating that populations of gas-phase oligodeoxynucleotide dications are zwitterionic.

  4. Observation of warm, higher energy electrons transiting a double layer in a helicon plasma

    SciTech Connect

    Sung, Yung-Ta Li, Yan; Scharer, John E.

    2015-03-15

    Measurements of an inductive RF helicon argon plasma double layer with two temperature electron distributions including a fast (>80 eV) tail are observed at 0.17 mTorr Ar pressure. The fast, untrapped electrons observed downstream of the double layer have a higher temperature (13 eV) than the trapped (T{sub e} = 4 eV) electrons. The reduction of plasma potential and density observed in the double layer region would require an upstream temperature ten times the measured 4 eV if occurring via Boltzmann ambipolar expansion. The experimental observation in Madison helicon experiment indicates that fast electrons with substantial density fractions can be created at low helicon operating pressures.

  5. Electron Capture Dissociation of Disulfide, Sulfur-Selenium, and Diselenide Bound Peptides

    NASA Astrophysics Data System (ADS)

    Li, Huilin; O'Connor, Peter B.

    2012-11-01

    To examine the electron capture dissociation (ECD) behavior of disulfide (S-S), sulfur-selenium (S-Se), and diselenide (Se-Se) bonds-containing peptides, a series of free cysteine (Cys) and selenocysteine (Sec) containing peptides were reacted to form interchain S-S, S-Se, and Se-Se bonds, and then studied using ECD with Fourier transform ion cyclotron mass spectrometry (FTICR MS). These results demonstrate that the radical has higher tendency to stay at selenium rather than sulfur after the cleavage of Se-S bonds by ECD. In addition, -SH (-33), -S (-32), and -S + H (-31) small neutral losses were all observed from the cleavage of C-S bonds of a disulfide bound peptide. Similar, but minor, fragments were also detected in S-Se bound peptides. In contrast, the cleavage of C-Se bonds of the Se-Se species mainly forms fragments with neutral loss of -Se + H (-78.90868), and the radical tends to stay on the selenium of its corresponding complementary pair. Although the electron affinities of S atom (2.07 eV) and Se atom (2.02 eV) are very close; they have very different reactivity towards electrons. The replacement of sulfur with selenium greatly increases the electron affinities of S-Se and Se-Se bonds comparing to S-S bonds (with an increase of electron affinity by about 0.20 eV by replacing a sulfur with a selenium) (Int J Quantum Chem 110:513-523, 2010), which in turn leads to different ECD fragmentation behavior and mechanisms. Our results are in good agreement with previously published ab initio calculations on Se-Se compounds by other groups.

  6. Two-dimensional quasi-double-layers in two-electron-temperature, current-free plasmas

    NASA Astrophysics Data System (ADS)

    Merino, Mario; Ahedo, Eduardo

    2013-02-01

    The expansion of a plasma with two disparate electron populations into vacuum and channeled by a divergent magnetic nozzle is analyzed with an axisymmetric model. The purpose is to study the formation and two-dimensional shape of a current-free double-layer in the case when the electric potential steepening can still be treated within the quasineutral approximation. The properties of this quasi-double-layer are investigated in terms of the relative fraction of the high-energy electron population, its radial distribution when injected into the nozzle, and the geometry and intensity of the applied magnetic field. The two-dimensional double layer presents a curved shape, which is dependent on the natural curvature of the equipotential lines in a magnetically expanded plasma and the particular radial distribution of high-energy electrons at injection. The double layer curvature increases the higher the nozzle divergence is, the lower the magnetic strength is, and the more peripherally hot electrons are injected. A central application of the study is the operation of a helicon plasma thruster in space. To this respect, it is shown that the curvature of the double layer does not increment the thrust, it does not modify appreciably the downstream divergence of the plasma beam, but it increases the magnetic-to-pressure thrust ratio. The present study does not attempt to cover current-free double layers involving plasmas with multiple populations of positive ions.

  7. Two-dimensional quasi-double-layers in two-electron-temperature, current-free plasmas

    SciTech Connect

    Merino, Mario; Ahedo, Eduardo

    2013-02-15

    The expansion of a plasma with two disparate electron populations into vacuum and channeled by a divergent magnetic nozzle is analyzed with an axisymmetric model. The purpose is to study the formation and two-dimensional shape of a current-free double-layer in the case when the electric potential steepening can still be treated within the quasineutral approximation. The properties of this quasi-double-layer are investigated in terms of the relative fraction of the high-energy electron population, its radial distribution when injected into the nozzle, and the geometry and intensity of the applied magnetic field. The two-dimensional double layer presents a curved shape, which is dependent on the natural curvature of the equipotential lines in a magnetically expanded plasma and the particular radial distribution of high-energy electrons at injection. The double layer curvature increases the higher the nozzle divergence is, the lower the magnetic strength is, and the more peripherally hot electrons are injected. A central application of the study is the operation of a helicon plasma thruster in space. To this respect, it is shown that the curvature of the double layer does not increment the thrust, it does not modify appreciably the downstream divergence of the plasma beam, but it increases the magnetic-to-pressure thrust ratio. The present study does not attempt to cover current-free double layers involving plasmas with multiple populations of positive ions.

  8. Recoil-ion momentum spectroscopy for He2+ + He electron capture reactions

    NASA Astrophysics Data System (ADS)

    Alessi, M.; Focke, P.; Otranto, S.

    2015-01-01

    Electron capture reactions for 3He2+ collisions on He at impact energies in the range 40 keV-300 keV have been studied using the Cold Target Recoil-Ion Momentum Spectroscopy setup which has recently became operational at the Centro Atomico Bariloche. State-selective charge exchange cross sections were obtained and in this work we present recoil-ion transverse momentum distributions. For targets with residual thermal motion, we show that the implementation of a back-projection algorithm based on the transverse momentum distribution component along a direction perpendicular to the jet direction provides results in agreement with those obtained by using previously cooled targets. Present results nicely fit the gaps in the datasets already published by other laboratories and are found to be in good agreement with classical trajectory Monte Carlo simulations.

  9. Electron capture by multicharged ions from hydrogen atoms at eV energies

    SciTech Connect

    Havener, C.C.; Nesnidal, M.P.; Porter, M.R.; Phaneuf, R.A.

    1990-01-01

    To quantitatively study electron capture during collisions of multiply charged ions with neutral atoms at near-thermal energies, keV-energy multicharged ion beams are merged with ground-state beams of H or D atoms of chosen velocity such that collisions in the relative energy range 1--1000 eV/amu result. Recent data for O{sup 3+}, O{sup 4+} + H(D) are presented and compared with theoretical predictions. Recently completed modifications to the apparatus are described that will provide a significant improvement in signal-to-background and angular collection. These improvements will allow measurements to be extended to lower energies, where effects due to the ion-induced dipole attraction may be evident.

  10. The Knowledge Program: an Innovative, Comprehensive Electronic Data Capture System and Warehouse

    PubMed Central

    Katzan, Irene; Speck, Micheal; Dopler, Chris; Urchek, John; Bielawski, Kay; Dunphy, Cheryl; Jehi, Lara; Bae, Charles; Parchman, Alandra

    2011-01-01

    Data contained in the electronic health record (EHR) present a tremendous opportunity to improve quality-of-care and enhance research capabilities. However, the EHR is not structured to provide data for such purposes: most clinical information is entered as free text and content varies substantially between providers. Discrete information on patients’ functional status is typically not collected. Data extraction tools are often unavailable. We have developed the Knowledge Program (KP), a comprehensive initiative to improve the collection of discrete clinical information into the EHR and the retrievability of data for use in research, quality, and patient care. A distinct feature of the KP is the systematic collection of patient-reported outcomes, which is captured discretely, allowing more refined analyses of care outcomes. The KP capitalizes on features of the Epic EHR and utilizes an external IT infrastructure distinct from Epic for enhanced functionality. Here, we describe the development and implementation of the KP. PMID:22195124

  11. Weak {gamma}-transition intensities in the electron capture decay of {sup 144}Pm

    SciTech Connect

    Robinson, S.J.; Altgilbers, A.S.; Hindi, M.M.; Norman, E.B.; Larimer, R.

    1996-09-01

    We have determined the absolute intensity of weak {gamma} transitions in the level scheme of {sup 144}Nd, observed following the electron capture decay of {sup 144}Pm. The absolute intensity of the 1397-keV {ital E}3 branch from the 2093-keV (5{sub 1}{sup {minus}}) level was determined to be (4.9 {plus_minus} 0.7) {times} 10{sup {minus}4}{percent}. This leads to a revised absolute transition rate of {ital B}({ital E}3;5{sub 1}{sup {minus}}{r_arrow}2{sup +}{sub 1})=26{sub {minus}12}{sup +15} Weisskopf units, which is still consistent with an interpretation of the 5{sub 1}{sup {minus}} level based on quadrupole-octupole coupling. {copyright} {ital 1996 The American Physical Society.}

  12. Large increase in the electron capture and excitation cross sections for Li+ colliding with atomic H under UV laser assistance

    NASA Astrophysics Data System (ADS)

    Domínguez-Gutiérrez, F. J.; Cabrera-Trujillo, R.

    2015-07-01

    Neutralization and ash products due to electron capture processes in plasmas reduce the efficiency of energy generation in fusion Tokamak reactors. Therefore, lithium ions have been used to improve the efficiency of energy generation where good control of the electron capture process is required. Here, we show that an intense (1.4× {{10}13} W cm-2), ultra-short (1 fs at full width half-maximum) Gaussian laser pulse in the UV region can enhance the electron capture process on L{{i}+}+H(1s) in the low collision keV energy region. We find a factor of 10 enhancement in electron capture cross-section at impact energies lower than 10 keV amu-1 for an 80 nm wavelength laser and a factor of 2 for the excitation process in the hydrogen atom as compared to the laser-free case. In contrast, for a 200 nm wavelength laser the increase of the electron capture cross-sections takes place around 1 keV amu-1 by a factor of 3 and no enhancement for the excitation process. Our results show that the UV assisted production of Li can be controlled, particularly for short UV wave-length for a specific collision energy range. We anticipate that our findings will facilitate UV laser control of the Li production in Tokamak reactors and encourage further experimental work in this system.

  13. Translational energy spectra for single-electron capture by O[sup 2+] in He, Ne, and Ar

    SciTech Connect

    Lee, A.R.; Wilkins, A.C.R.; Leather, C.; Brenton, A.G. Mass Spectrometry Research Unit, University College of Swansea, Singleton Park, Swansea SA2 8PP )

    1994-08-01

    High-resolution single-electron capture spectra have been obtained for O[sup 2+] ions colliding with He, Ne, and Ar at 4-keV energy. For the He and Ne targets the dominant capture channels involve transitions from the ground [sup 3][ital P] state of O[sup 2+] to the first and second excited states ([sup 2][ital D][sup [ital o

  14. Role of the bound-state wave function in capture-loss rates: Slow proton in an electron gas

    SciTech Connect

    Alducin, M.; Nagy, I.

    2003-07-01

    Capture and loss rates for protons moving in an electron gas are calculated using many-body perturbation theory. The role of the form of the bound-state wave function for weakly bound states around the proton is analyzed. We find significant differences (up to a factor of 2 higher) in the values of Auger capture and loss rates when using Hulthen-type instead of hydrogenic wave functions. Its relevance in stopping power is briefly discussed.

  15. Ab initio investigation of electron capture by Cl{sup 7+} ions from H

    SciTech Connect

    Zhao, L. B.; Stancil, P. C.; Watanabe, A.; Kimura, M.

    2007-08-15

    An investigation of charge transfer in collisions of ground-state Cl{sup 7+} with H has been conducted based on a fully quantum-mechanical molecular-orbital close-coupling (QMOCC) approach. The charge-transfer process Cl{sup 7+}({sup 1}S)+H{yields}Cl{sup 6+}(2p{sup 6}nl {sup 2}S,{sup 2}P{sup o},{sup 2}D,{sup 2}F{sup o},{sup 2}G)+H{sup +} with n=5 and 6 is taken into account for collision energies between 10{sup -4} eV/u and 1 keV/u. The relevant adiabatic potentials and nonadiabatic coupling matrix elements for the ClH{sup 7+} system are evaluated with the configuration-interaction method. The investigation shows that electron capture into the 5d, 5f, 5g, and 6p states dominates for collision energies less than {approx}1 eV/u, while above 100 eV/u the 5s, 5p, 5d, and 6p are the primary capture channels. Comparison with experimental data for collisions of Cl{sup 7+}({sup 1}S) with D reveals a discrepancy over the full range of measured energies (5-430 eV/u), while no significant isotope effect is found for QMOCC calculations with deuterium. Furthermore, comparison with a previous calculation of the one-electron N{sup 7+}+H system, as well as measurements of the multielectron Al{sup 7+}+H and Fe{sup 7+}+H systems, suggests that the electronic structure of the core has a non-negligible effect on the charge-transfer process. A one-electron model for relative l distributions is found to agree with the QMOCC results for n=5 between 100 and 1000 eV/u, but fails at lower collision energies. Finally, state-selective and total rate coefficients are given for temperatures between 10 and 200 000 K.

  16. THE n-DISTRIBUTION OF ELECTRONS AND DOUBLE LAYERS IN THE ELECTRON-BEAM-RETURN-CURRENT SYSTEM OF SOLAR FLARES

    SciTech Connect

    Karlicky, Marian

    2012-05-01

    We investigate processes in the electron-beam-return-current system in the impulsive phase of solar flares to answer a question about the formation of the n-electron distribution detected in this phase of solar flares. An evolution of the electron-beam-return-current system with an initial local density depression is studied using a three-dimensional electromagnetic particle-in-cell model. In the system the strong double layer is formed. Its electric field potential increases with the electron beam flux. In this electric field potential, the electrons of background plasma are strongly accelerated and propagate in the return-current direction. The high-energy part of their distribution at the high-potential side of the strong double layer resembles that of the n-distribution. Thus, the detection of the n-distributions, where a form of the high-energy part of the distribution is the most important, can indicate the presence of strong double layers in solar flares. The similarity between processes in solar flare loops and those in the downward current region of the terrestrial aurora, where the double layers were observed by FAST satellite, supports this idea.

  17. Analytical distance distributions in systems of spherical symmetry with applications to double electron-electron resonance

    NASA Astrophysics Data System (ADS)

    Kattnig, Daniel R.; Hinderberger, Dariush

    2013-05-01

    Based on a simple geometrical approach, we derive analytical expression of the probability density functions (pdfs) of distance of probe molecules distributed homogeneously in spherical aggregates with shell structure. These distance distributions can be utilized in the investigation of double electron-electron resonance (DEER) data of disordered nanometer-sized spin clusters. Structural insights and geometrical parameters of the aggregates can be extracted by modeling the DEER time traces based on the analytical pdfs. This approach is efficient and avoids difficulties of the model-free solution of the inverse problem that are related to multi-spin effects, limited excitation bandwidth, bias introduced by the regularization scheme, or ambiguity resulting from broad distance distributions. The derived pdfs can serve as building blocks, from which the distance distributions in arbitrary spherically symmetric objects can be assembled. The scenario of the pumped species being chemically distinct from the observed species is covered as well as that of a single type of probe molecules. We demonstrate the merits of analytical distance distributions by studying the distribution of three different spin probes in SDS micelles. By simultaneously analyzing DEER data corresponding to different spin probe concentrations, the distribution of the spin probes over the micelle can be determined. Employing Bayesian inference it is found that for all probes studied, a spherical shell model is most appropriate among the studied models and by orders of magnitude more likely than a homogeneous distribution in a ball. This statement also applies to probes that are deemed nonpolar. We envisage that the spin probe distributions in disordered soft and hard matter systems can now be quantified using DEER spectroscopy with greater precision and reduced ambiguity.

  18. Combining gas phase electron capture and IRMPD action spectroscopy to probe the electronic structure of a metastable reduced organometallic complex containing a non-innocent ligand.

    PubMed

    Katari, Madanakrishna; Payen de la Garanderie, Eleonore; Nicol, Edith; Steinmetz, Vincent; van der Rest, Guillaume; Carmichael, Duncan; Frison, Gilles

    2015-10-21

    Combining electron capture dissociation mass spectrometry and infrared multiple photon dissociation action spectroscopy allows the formation, selection and characterisation of reduced metal complexes containing non-innocent ligands. Zinc complexes containing diazafluorenone ligands have been studied and the localisation of the single electron on the metal atom in the mono-ligated complex has been demonstrated. PMID:26051020

  19. Integrating research data capture into the electronic health record workflow: real-world experience to advance innovation.

    PubMed

    Laird-Maddox, Marsha; Mitchell, Susan B; Hoffman, Mark

    2014-01-01

    As the adoption of electronic health records (EHRs) increases, more opportunities are available for leveraging the system and the data to facilitate research. Historically, for patients enrolled in clinical research trials or studies, data have been documented in the medical record, and then study-related data are manually reentered into an electronic case report form in a research system. By utilizing data collected in the EHR to prepopulate electronic case report forms, manual transcription is reduced, data quality is improved, and the workflow for capturing research data is streamlined. Past efforts to integrate EHRs and research systems for the purposes of data capture have demonstrated that interoperability is possible. This article highlights how Cerner Corporation and Florida Hospital collaborated to extend an existing standard to implement a workflow called Integrated Data Capture. PMID:25593571

  20. Integrating Research Data Capture into the Electronic Health Record Workflow: Real-World Experience to Advance Innovation

    PubMed Central

    Laird-Maddox, Marsha; Mitchell, Susan B.; Hoffman, Mark

    2014-01-01

    As the adoption of electronic health records (EHRs) increases, more opportunities are available for leveraging the system and the data to facilitate research. Historically, for patients enrolled in clinical research trials or studies, data have been documented in the medical record, and then study-related data are manually reentered into an electronic case report form in a research system. By utilizing data collected in the EHR to prepopulate electronic case report forms, manual transcription is reduced, data quality is improved, and the workflow for capturing research data is streamlined. Past efforts to integrate EHRs and research systems for the purposes of data capture have demonstrated that interoperability is possible. This article highlights how Cerner Corporation and Florida Hospital collaborated to extend an existing standard to implement a workflow called Integrated Data Capture. PMID:25593571

  1. An Assessment of Family History Information Captured in an Electronic Health Record

    PubMed Central

    Polubriaginof, Fernanda; Tatonetti, Nicholas P.; Vawdrey, David K.

    2015-01-01

    Family history is considered a core element of clinical care. In this study we assessed the quality of family history data captured in an established commercial electronic health record (EHR) at a large academic medical center. Because the EHR had no centralized location to store family history information, it was collected as part of clinical notes in structured or free-text format. We analyzed differences between 10,000 free-text and 9,121 structured family history observations. Each observation was classified according to disease presence/absence and family member affected (e.g., father, mother, etc.). The structured notes did not collect a complete family history as defined by standards endorsed by the U.S. Agency for Healthcare Research and Quality; the free-text notes contained more information than the structured notes, but still not enough to be considered “complete.” Several barriers remain for collecting complete, useful family history data in electronic health records. PMID:26958303

  2. Electron-capture Supernovae as The Origin of Elements Beyond Iron

    NASA Astrophysics Data System (ADS)

    Wanajo, Shinya; Janka, Hans-Thomas; Müller, Bernhard

    2011-01-01

    We examine electron-capture supernovae (ECSNe) as sources of elements heavier than iron in the solar system and in Galactic halo stars. Nucleosynthesis calculations are performed on the basis of thermodynamic histories of mass elements from a fully self-consistent, two-dimensional hydrodynamic explosion model of an ECSN. We find that neutron-rich convective lumps with an electron fraction down to Y e,min = 0.40, which are absent in the one-dimensional counterpart, allow for interesting production of elements between the iron group and N = 50 nuclei (from Zn to Zr, with little Ga) in nuclear (quasi-)equilibrium. Our models yield very good agreement with the Ge, Sr, Y, and Zr abundances of r-process-deficient Galactic halo stars and constrain the occurrence of ECSNe to ~4% of all stellar core-collapse events. If tiny amounts of additional material with slightly lower Y e,min down to ~0.30-0.35 were also ejected—which presently cannot be excluded because of the limitations of resolution and two dimensionality of the model—a weak r-process can yield elements beyond N = 50 up to Pd, Ag, and Cd as observed in the r-process-deficient stars.

  3. Electron capture by U(91+) and U(92+) and ionization of U(90+) and U(91+)

    NASA Technical Reports Server (NTRS)

    Gould, H.; Greiner, D.; Lindstrom, P.; Symons, T. J. M.; Crawford, H.

    1984-01-01

    U(92+)/U(91+) and U(91+)/U(90+) electron-capture and ionization cross sections and equilibrium charge-state distributions are measured experimentally in mylar, Cu and Ta of varying thickness. Relativistic U(68+) ions at 437 or 962 MeV/nucleon are produced by a heavy-ion linear accelerator and synchrotron in tandem and passed through the target material into a magnetic specrometer and position-sensitive proportional counter for evaluation of charge states. The results are presented graphically and discussed. At 962 MeV/nucleon, beams containing 85 percent bare U(92+) nuclei are obtained using 150-mg/sq cm Cu or 85-mg/sq cm Ta; at 437 MeV/nucleon, 50 percent bare U(92+) nuclei are obtained with 90-mg/sq cm Cu. The techniques decribed can be applied to produce beams of bare U nuclei for acceleration to ultrarelativistic speeds or beams of few-electron U for atomic-physics experiments on quantum electrodynamics.

  4. Electron-hole capture in polymer heterojunction light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Greenham, Neil

    2005-03-01

    Polymer light-emitting diodes based on blends of polyfluorene derivatives show very high efficiencies and low drive voltages. Electron-hole capture in these devices directly produces long-lived exciplex states where the electron and hole are predominantly localized on opposite sides of the heterojunction. The exciplex may then be thermally excited to form an intra-chain exciton, which can itself either emit, or be recycled to reform the exciplex. I will review the physics of exciplex formation and emission in these devices, and will show that exciplex formation rates are consistent with low free charge densities at the heterojunction. I will present evidence that the rate of charge transfer at polyfluorene heterojunctions can be modulated with an applied electric field, leading in some cases to an increase in photoluminescence efficiency with applied field. I will also present recent results showing enhanced triplet exciton formation after photoexcitation in polyfluorene blends, and will discuss the implications of the results for polymer light-emitting and photovoltaic devices.

  5. Two-band electron transport in a double quantum well

    NASA Astrophysics Data System (ADS)

    Fletcher, R.; Tsaousidou, M.; Smith, T.; Coleridge, P. T.; Wasilewski, Z. R.; Feng, Y.

    2005-04-01

    The carrier densities and mobilities have been measured for the first two populated subbands in a GaAs double quantum well (DQW) as a function of the top gate voltage Vg . The densities and quantum mobilities ( μiq , i=1,2 ) were obtained from the de Haas-Shubnikov oscillations. The transport mobilities (μit) were determined from the semiclassical low-field magnetoresistance with intersubband scattering taken into account. At 0.32K the experimental data on both μit and μiq , as a function of Vg , lie on two curves which cross at the resonance point as expected from theoretical considerations. At 1.09K and 4.2K the μit curves no longer cross at resonance, but show a gap. The reason for this is not known. The mobilities have been calculated in the low-temperature limit within the Boltzmann framework by assuming that they are limited by scattering due to ionized impurities located at the outside interfaces. The assumption of short-range scattering is justified by the relatively small value of the ratio μit/μiq that is measured in the present system. The theoretical values obtained for μit and μiq are in reasonable agreement with the experiment for all values of Vg examined. We have also calculated the resistivity and intersubband scattering rates of the DQW as a function of Vg and again find good agreement with measured values.

  6. Strong coupling theory for electron-mediated interactions in double-exchange models

    NASA Astrophysics Data System (ADS)

    Ishizuka, Hiroaki; Motome, Yukitoshi

    2015-07-01

    We present a theoretical framework for evaluating effective interactions between localized spins mediated by itinerant electrons in double-exchange models. Performing the expansion with respect to the spin-dependent part of the electron hopping terms, we show a systematic way of constructing the effective spin model in the large Hund's coupling limit. As a benchmark, we examine the accuracy of this method by comparing the results with the numerical solutions for the spin-ice type model on a pyrochlore lattice. We also discuss an extension of the method to the double-exchange models with Heisenberg and X Y localized spins.

  7. Ion-acoustic double-layers in a magnetized plasma with nonthermal electrons

    SciTech Connect

    Rios, L. A.; Galvão, R. M. O.

    2013-11-15

    In the present work we investigate the existence of obliquely propagating ion-acoustic double layers in magnetized two-electron plasmas. The fluid model is used to describe the ion dynamics, and the hot electron population is modeled via a κ distribution function, which has been proved to be appropriate for modeling non-Maxwellian plasmas. A quasineutral condition is assumed to investigate these nonlinear structures, which leads to the formation of double-layers propagating with slow ion-acoustic velocity. The problem is investigated numerically, and the influence of parameters such as nonthermality is discussed.

  8. The BOEING double subharmonic electron injector - performance measurements

    SciTech Connect

    Adamski, J.L.; Gallagher, W.J.; Kennedy, R.C.; Stoffstall, D.R.; Tyson, E.L.; Yeremian, A.D.

    1985-10-01

    A two stage subharmonic injector has been installed and tested on the Boeing S band linac. The injector is designed as a prototype front end for a high voltage linac for free electron laser research. This accelerator will require long macropulse trains of widely spaced high current micropulses. Single micropulse output beams of 1-2 nC, 10 ps width, 1% full width energy spread and normalized emittance of epsilon /SUB n/ = US el r/phi/ = 0.01 cm-rad have been measured. The data are in good agreement with model predictions.

  9. Boundary-corrected four-body continuum-intermediate-state method: Single-electron capture from heliumlike atomic systems by fast nuclei

    NASA Astrophysics Data System (ADS)

    Mančev, Ivan; Milojević, Nenad; Belkić, Dževad

    2015-06-01

    Single charge exchange in collisions between bare projectiles and heliumlike atomic systems at intermediate and high incident energies is examined by using the four-body formalism of the first- and second-order theories. The main purpose of the present study is to investigate the relative importance of the intermediate ionization continua of the captured electron compared to the usual direct path of the single electron transfer from a target to a projectile. In order to achieve this goal, comprehensive comparisons are made between the four-body boundary-corrected continuum-intermediate-states (BCIS-4B) method and the four-body boundary-corrected first Born (CB1-4B) method. The perturbation potential is the same in the CB1-4B and BCIS-4B methods. Both methods satisfy the correct boundary conditions in the entrance and exit channels. However, unlike the CB1-4B method, the second-order BCIS-4B method takes into account the electronic Coulomb continuum-intermediate states in either the entrance or the exit channel depending on whether the post or the prior version of the transition amplitude is used. Hence, by comparing the results from these two theories, the relative importance of the intermediate ionization electronic continua can be assessed within the four-body formalism of scattering theory. The BCIS-4B method predicts the usual second-order effect through double scattering of the captured electron on two nuclei as a quantum-mechanical counterpart of the Thomas classical two-step, billiard-type collision. The physical mechanism for this effect in the BCIS-4B method is also comprised of two steps such that ionization occurs first. This is followed by capture of the electron by the projectile with both processes taking place on the energy shell. Moreover, the role of the second, noncaptured electron in a heliumlike target is revisited. To this end, the BCIS-4B method describes the effect of capture of one electron by the interaction of the projectile nucleus with

  10. Determination of phenoxy acid herbicides in water by electron-capture and microcoulometric gas chromatography

    USGS Publications Warehouse

    Goerlitz, D.F.; Lamar, William L.

    1967-01-01

    A sensitive gas chromatographic method using microcoulometric titration and electron-capture detection for the analysis of 2,4-D, silvex, 2,4,5-T, and other phenoxy acid herbicides in water is described. The herbicides are extracted from unfiltered water samples (800-1,000 ml) by use of ethyl ether ; then the herbicides are concentrated and esterilied. To allow the analyst a choice, two esterilication procedures--using either boron trifluoride-methanol or diazomethane--are evaluated. Microcoulometric gas chromatography is specific for the detection of halogenated compounds such as the phenoxy acid herbicides whereas it does not respond to nonhalogenated components. Microcoulometric gas chromatography requires care and patience. It is not convenient for rapid screening of l-liter samples that contain less than 1 microgram of the herbicide. Although electroncapture gas chromatography is less selective and more critically affected by interfering substances, it is, nevertheless, convenient and more sensitive than microcoulometric gas chromatography. Two different liquid phases are used in the gas chromatographic columns--DC-200 silicone in one column and QF-1 silicone in the other. The performance of both columns is improved by the addition of Carbowax 20M. The Gas Chrom Q support is coated with the liquid phases by the 'frontal-analysis' technique. The practical lower limits for measurement of the phenoxy acid herbicides in water primarily depend upon the sample size, interferences present, anal instrumentation used. With l-liter samples of water, the practical lower limits of measurement are 10 ppt (parts per trillion) for 2,4-D and 2 ppt for silvex and 2,4,5-T when electron-capture detection is used, and approximately 20 ppt for each herbicide when analyzed by microcoulometric-titration gas chromatography. Recoveries of the herbicides immediately after addition to unfiltered water samples averaged 92 percent for 2,4-D, 90 percent for silvex, and 98 percent for 2

  11. Electrochemical Electron Transfer and Proton-Coupled Electron Transfer: Effects of Double Layer and Ionic Environment on Solvent Reorganization Energies.

    PubMed

    Ghosh, Soumya; Soudackov, Alexander V; Hammes-Schiffer, Sharon

    2016-06-14

    Electron transfer and proton coupled electron transfer (PCET) reactions at electrochemical interfaces play an essential role in a broad range of energy conversion processes. The reorganization energy, which is a measure of the free-energy change associated with solute and solvent rearrangements, is a key quantity for calculating rate constants for these reactions. We present a computational method for including the effects of the double layer and ionic environment of the diffuse layer in calculations of electrochemical solvent reorganization energies. This approach incorporates an accurate electronic charge distribution of the solute within a molecular-shaped cavity in conjunction with a dielectric continuum treatment of the solvent, ions, and electrode using the integral equations formalism polarizable continuum model. The molecule-solvent boundary is treated explicitly, but the effects of the electrode-double layer and double layer-diffuse layer boundaries, as well as the effects of the ionic strength of the solvent, are included through an external Green's function. The calculated total reorganization energies agree well with experimentally measured values for a series of electrochemical systems, and the effects of including both the double layer and ionic environment are found to be very small. This general approach was also extended to electrochemical PCET and produced total reorganization energies in close agreement with experimental values for two experimentally studied PCET systems. PMID:27111050

  12. Relativistic contributions to single and double core electron ionization energies of noble gases

    SciTech Connect

    Niskanen, J.; Norman, P.; Aksela, H.; Aagren, H.

    2011-08-07

    We have performed relativistic calculations of single and double core 1s hole states of the noble gas atoms in order to explore the relativistic corrections and their additivity to the ionization potentials. Our study unravels the interplay of progression of relaxation, dominating in the single and double ionization potentials of the light elements, versus relativistic one-electron effects and quantum electrodynamic effects, which dominate toward the heavy end. The degree of direct relative additivity of the relativistic corrections for the single electron ionization potentials to the double electron ionization potentials is found to gradually improve toward the heavy elements. The Dirac-Coulomb Hamiltonian is found to predict a scaling ratio of {approx}4 for the relaxation induced relativistic energies between double and single ionization. Z-scaling of the computed quantities were obtained by fitting to power law. The effects of nuclear size and form were also investigated and found to be small. The results indicate that accurate predictions of double core hole ionization potentials can now be made for elements across the full periodic table.

  13. Suppression of correlated electron escape in double ionization in strong laser fields

    NASA Astrophysics Data System (ADS)

    Eckhardt, Bruno; Prauzner-Bechcicki, Jakub S.; Sacha, Krzysztof; Zakrzewski, Jakub

    2008-01-01

    The effect of the Pauli exclusion principle on double ionization of He atoms by strong, linearly polarized laser pulses is analyzed. We show that correlated electron escape, with electron momenta symmetric with respect to the field polarization axis, is suppressed if atoms are initially prepared in the metastable state S3 . The effect is a consequence of selection rules for the transition to the appropriate outgoing two-electron states. We illustrate the suppression in numerical calculations of electron and ion momentum distributions within a reduced dimensionality model.

  14. Role of elastic projectile-electron scattering in double ionization of helium by fast proton impact

    NASA Astrophysics Data System (ADS)

    Schulz, M.; Ciappina, M. F.; Kirchner, T.; Fischer, D.; Moshammer, R.; Ullrich, J.

    2009-04-01

    We present a systematic study of atomic four-body fragmentation dynamics. To this end we have measured a variety of multiple differential double ionization cross sections for 6 MeV p+He collisions. The data are compared to a first-order calculation with correlated electrons and to a simulation representing a second-order process, with some experimental results seemingly in favor of the first, others in agreement with the second approach. This apparent conflict can be resolved by accounting for elastic scattering between the projectile and one electron already promoted to the continuum through electron-electron correlation in the first-order process.

  15. High-resolution study of electron capture by 72- and 52-MeV 3He projectiles from targets of high atomic number

    NASA Astrophysics Data System (ADS)

    Katayama, I.; Ikegami, H.; Ogawa, H.; Haruyama, Y.; Tozaki, M.; Aoki, A.; Fukuzawa, F.; Yoshida, K.; Sugai, I.

    1996-01-01

    An electron capture at the cyclotron energy has been explored by using a high-resolution magnetic spectrograph. The K-shell electron capture from heavy elements (V, Cr, Cu, Ge, Nb, Ag, and Sn) by 3He2+ projectiles at 52 and 72 MeV was measured. The dependence of the cross sections on the atomic number of the target obtained at these two energies are compared with current electron-capture theories.

  16. Shock waves and double layers in electron degenerate dense plasma with viscous ion fluids

    SciTech Connect

    Mamun, A. A.; Zobaer, M. S.

    2014-02-15

    The properties of ion-acoustic shock waves and double layers propagating in a viscous degenerate dense plasma (containing inertial viscous ion fluid, non-relativistic and ultra-relativistic degenerate electron fluid, and negatively charged stationary heavy element) is investigated. A new nonlinear equation (viz. Gardner equation with additional dissipative term) is derived by the reductive perturbation method. The properties of the ion-acoustic shock waves and double layers are examined by the analysis of the shock and double layer solutions of this new equation (we would like to call it “M-Z equation”). It is found that the properties of these shock and double layer structures obtained from this analysis are significantly different from those obtained from the analysis of standard Gardner or Burgers’ equation. The implications of our results to dense plasmas in astrophysical objects (e.g., non-rotating white dwarf stars) are briefly discussed.

  17. Shock waves and double layers in electron degenerate dense plasma with viscous ion fluids

    NASA Astrophysics Data System (ADS)

    Mamun, A. A.; Zobaer, M. S.

    2014-02-01

    The properties of ion-acoustic shock waves and double layers propagating in a viscous degenerate dense plasma (containing inertial viscous ion fluid, non-relativistic and ultra-relativistic degenerate electron fluid, and negatively charged stationary heavy element) is investigated. A new nonlinear equation (viz. Gardner equation with additional dissipative term) is derived by the reductive perturbation method. The properties of the ion-acoustic shock waves and double layers are examined by the analysis of the shock and double layer solutions of this new equation (we would like to call it "M-Z equation"). It is found that the properties of these shock and double layer structures obtained from this analysis are significantly different from those obtained from the analysis of standard Gardner or Burgers' equation. The implications of our results to dense plasmas in astrophysical objects (e.g., non-rotating white dwarf stars) are briefly discussed.

  18. Projectile energy and atomic number dependence of electron capture from pair production in relativistic heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Belkacem, A.; Gould, Harvey; Feinberg, B.; Bossingham, R.; Meyerhof, W. E.

    1994-10-01

    We report the first measurement of the energy dependence of electron capture from electron-positron pair production in relativistic heavy ion collisions. For a La57+ beam incident on Au, Ag, and Cu targets at energies of 0.405, 0.956, and 1.3 GeV/u we find that the cross sections for capture from pair production and the free pair production process increase with increasing collision energy at similar rates. Combining with uranium data reported previously gives a projectile atomic number dependence for 0.956 GeV/u ions on a Au target of Z6.54+/-0.65p for capture from pair production and Z1.53+/-0.80p for the free pair production process.

  19. Effect of collective response on electron capture and excitation in collisions of highly charged ions with fullerenes.

    PubMed

    Kadhane, U; Misra, D; Singh, Y P; Tribedi, Lokesh C

    2003-03-01

    Projectile deexcitation Lyman x-ray emission following electron capture and K excitation has been studied in collisions of bare and Li-like sulphur ions (of energy 110 MeV) with fullerenes (C(60)/C(70)) and different gaseous targets. The intensity ratios of different Lyman x-ray lines in collisions with fullerenes are found to be substantially lower than those for the gas targets, both for capture and excitation. This has been explained in terms of a model based on "solidlike" effect, namely, wakefield induced stark mixing of the excited states populated via electron capture or K excitation: a collective phenomenon of plasmon excitation in the fullerenes under the influence of heavy, highly charged ions. PMID:12689221

  20. Study of photon emission by electron capture during solar nuclei acceleration. 2: Delimitation of conditions for charge transfert establishment

    NASA Technical Reports Server (NTRS)

    Perez-Peraza, J.; Alvarez, M.; Gallegos, A.

    1985-01-01

    The conditions for establishment of charge transfer during acceleration of nuclei up to Fe, for typical conditions of solar flare regions T = 5 x 10 to the 3rd power to 2.5 x 10 to the 8th power degrees K were explored. Results show that such conditions are widely assorted, depending on the acceleration mechanism, the kind of projections and their velocity, the target elements, the source temperature and consequently on the degree of ionization of matter and the local charge state of the accelerated ions. Nevertheless, in spite of that assorted behavior, there are some general tendencies that can be summarized as follows. In atomic H electron capture is systematically established from thermal energies up to high energies, whatever the element and for both acceleration process. For a given element and fixed temperature (T), the probability and energy domain of electron capture and loss with Fermi are higher than with Betatron acceleration. For a given acceleration process the heavier the ion the higher the probability and the wider the energy range for electron capture and loss. For given acceleration mechanism and fixed element the importance and energy domain of capture and loss increase with T: for those reasons, the energy range of charge equilibrium (illustrated with solid lines on the next figs.) is wider with Fermi and increases with temperature and atomic number of projectiles. For the same reasons, electron loss is smaller while the lighter the element, the lower the temperature and the Betatron process, such that there are conditions for which electron loss is not allowed at low energies, but only electron capture is established.

  1. DICOM for Clinical Research: PACS-Integrated Electronic Data Capture in Multi-Center Trials.

    PubMed

    Haak, Daniel; Page, Charles-E; Reinartz, Sebastian; Krüger, Thilo; Deserno, Thomas M

    2015-10-01

    Providing surrogate endpoints in clinical trials, medical imaging has become increasingly important in human-centered research. Nowadays, electronic data capture systems (EDCS) are used but binary image data is integrated insufficiently. There exists no structured way, neither to manage digital imaging and communications in medicine (DICOM) data in EDCS nor to interconnect EDCS with picture archiving and communication systems (PACS). Manual detours in the trial workflow yield errors, delays, and costs. In this paper, requirements for a DICOM-based system interconnection of EDCS and research PACS are analysed. Several workflow architectures are compared. Optimized for multi-center trials, we propose an entirely web-based solution integrating EDCS, PACS, and DICOM viewer, which has been implemented using the open source projects OpenClinica, DCM4CHEE, and Weasis, respectively. The EDCS forms the primary access point. EDCS to PACS interchange is integrated seamlessly on the data and the context levels. DICOM data is viewed directly from the electronic case report form (eCRF), while PACS-based management is hidden from the user. Data privacy is ensured by automatic de-identification and re-labelling with study identifiers. Our concept is evaluated on a variety of 13 DICOM modalities and transfer syntaxes. We have implemented the system in an ongoing investigator-initiated trial (IIT), where five centers have recruited 24 patients so far, performing decentralized computed tomography (CT) screening. Using our system, the chief radiologist is reading DICOM data directly from the eCRF. Errors and workflow processing time are reduced. Furthermore, an imaging database is built that may support future research. PMID:26001521

  2. Kuang's Semi-Classical Formalism for Calculating Electron Capture Cross Sections and Sample Application for ENA Modeling

    NASA Technical Reports Server (NTRS)

    Barghouty, A. F.

    2013-01-01

    Accurate estimates of electron-capture cross sections at energies relevant to ENA modeling (approx. few MeV per nucleon) and for multi-electron ions must rely on detailed, but computationally expensive, quantummechanical description of the collision process. Kuang's semi-classical approach is an elegant and efficient way to arrive at these estimates. Motivated by ENA modeling efforts, we shall briefly present this approach along with sample applications and report on current progress.

  3. PROBING ELECTRON-CAPTURE SUPERNOVAE: X-RAY BINARIES IN STARBURSTS

    SciTech Connect

    Linden, T.; Sepinsky, J. F.; Kalogera, V.; Belczynski, K.

    2009-07-10

    We develop population models of high-mass X-ray binaries (HMXBs) formed after bursts of star formation and we investigate the effect of electron-capture supernovae (ECS) of massive ONeMg white dwarfs and the hypothesis that ECS events are associated with typically low supernova kicks imparted to the nascent neutron stars. We identify an interesting ECS bump in the time evolution of HMXB numbers; this bump is caused by significantly increased production of wind-fed HMXBs 20-60 Myr post-starburst. The amplitude and age extent of the ECS bump depend on the strength of ECS kicks and the mass range of ECS progenitors. We also find that ECS-HMXBs form through a specific evolutionary channel that is expected to lead to binaries with Be donors in wide orbits. These characteristics, along with their sensitivity to ECS properties, provide us with an intriguing opportunity to probe ECS physics and progenitors through studies of starbursts of different ages. Specifically, the case of the Small Magellanic Cloud, with a significant observed population of Be-HMXBs and starburst activity 30-60 Myr ago, arises as a promising laboratory for understanding the role of ECS in neutron star formation.

  4. Comparison of peptide mass mapping and electron capture dissociation as assays for histone posttranslational modifications

    NASA Astrophysics Data System (ADS)

    Zhang, Liwen; Freitas, Michael A.

    2004-05-01

    Posttranslational modifications of core histones play a critical role in the structure of chromatin and the regulation of gene activities. Improved techniques for determining these modification sites may lead to a better understanding of histone regulation at the molecular level. LC-MS peptide mass mapping was performed on pepsin, trypsin and Glu-C digests of bovine thymus H4 using a QqTOF instrument. The well established modification sites of H4 (acetylation of K8, 12, 16 and methylation of K20) were observed in addition to several recently discovered modifications including: methylation of K31, 44, 59 and acetylation of K20, 77, 79. For comparison, electron capture dissociation (ECD) was performed on intact H4 along with several peptides from enzymatic digestion. The results from the ECD experiments of histone H4 indicated the acetylation of K5, 12, 16, 31, 91 and the methylation of K20 and 59 in good agreement with the result from peptide mapping. The work is dedicated to Alan G. Marshall on his 60th birthday. His endeavors in the advancement of FT-ICR facilitated experiments reported herein.

  5. Neuroinformatics Software Applications Supporting Electronic Data Capture, Management, and Sharing for the Neuroimaging Community.

    PubMed

    Nichols, B Nolan; Pohl, Kilian M

    2015-09-01

    Accelerating insight into the relation between brain and behavior entails conducting small and large-scale research endeavors that lead to reproducible results. Consensus is emerging between funding agencies, publishers, and the research community that data sharing is a fundamental requirement to ensure all such endeavors foster data reuse and fuel reproducible discoveries. Funding agency and publisher mandates to share data are bolstered by a growing number of data sharing efforts that demonstrate how information technologies can enable meaningful data reuse. Neuroinformatics evaluates scientific needs and develops solutions to facilitate the use of data across the cognitive and neurosciences. For example, electronic data capture and management tools designed to facilitate human neurocognitive research can decrease the setup time of studies, improve quality control, and streamline the process of harmonizing, curating, and sharing data across data repositories. In this article we outline the advantages and disadvantages of adopting software applications that support these features by reviewing the tools available and then presenting two contrasting neuroimaging study scenarios in the context of conducting a cross-sectional and a multisite longitudinal study. PMID:26267019

  6. Strong neutrino cooling by cycles of electron capture and β- decay in neutron star crusts.

    PubMed

    Schatz, H; Gupta, S; Möller, P; Beard, M; Brown, E F; Deibel, A T; Gasques, L R; Hix, W R; Keek, L; Lau, R; Steiner, A W; Wiescher, M

    2014-01-01

    The temperature in the crust of an accreting neutron star, which comprises its outermost kilometre, is set by heating from nuclear reactions at large densities, neutrino cooling and heat transport from the interior. The heated crust has been thought to affect observable phenomena at shallower depths, such as thermonuclear bursts in the accreted envelope. Here we report that cycles of electron capture and its inverse, β(-) decay, involving neutron-rich nuclei at a typical depth of about 150 metres, cool the outer neutron star crust by emitting neutrinos while also thermally decoupling the surface layers from the deeper crust. This 'Urca' mechanism has been studied in the context of white dwarfs and type Ia supernovae, but hitherto was not considered in neutron stars, because previous models computed the crust reactions using a zero-temperature approximation and assumed that only a single nuclear species was present at any given depth. The thermal decoupling means that X-ray bursts and other surface phenomena are largely independent of the strength of deep crustal heating. The unexpectedly short recurrence times, of the order of years, observed for very energetic thermonuclear superbursts are therefore not an indicator of a hot crust, but may point instead to an unknown local heating mechanism near the neutron star surface. PMID:24291788

  7. Rapid determination of acrylamide contaminant in conventional fried foods by gas chromatography with electron capture detector.

    PubMed

    Zhang, Yu; Dong, Yi; Ren, Yiping; Zhang, Ying

    2006-05-26

    Gas chromatography coupled with electron capture detector (GC-ECD) was successfully developed and applied for the rapid determination of acrylamide in conventional fried foods, such as potato crisps, potato chips, and fried chicken wings. The method included defatting with n-hexane, extraction with aqueous solution of sodium chloride (NaCl), derivatization with potassium bromate (KBrO3) and potassium bromide (KBr), and liquid-liquid extraction with ethyl acetate. The final acrylamide extract was analyzed by GC-ECD for quantification and by GC-MS for confirmation. The chromatographic analysis was performed on the HP-INNOWax capillary column, and good retention and peak response of acrylamide were achieved under the optimal conditions (numbers of theoretical plates N = 83,815). The limit of detection (LOD) was estimated to be 0.1 microg kg(-1) on the basis of ECD technique. Recoveries of acrylamide from conventional samples spiked at levels of 150, 500 and 1000 microg kg(-1) (n = 4 for each level) ranged between 87 and 97% with relative standard deviations (RSD) of less than 4%. Furthermore, the GC-ECD method showed that no clean-up steps of acrylamide derivative would be performed prior to injection and was slightly more sensitive than the MS/MS-based methods. Validation and quantification results demonstrated that this method should be regarded as a new, low-cost, and robust alternative for conventional investigation of acrylamide. PMID:16580677

  8. Characterization of neurohistone variants and post-translational modifications by electron capture dissociation mass spectrometry

    NASA Astrophysics Data System (ADS)

    Garcia, Benjamin A.; Siuti, Nertila; Thomas, C. Eric; Mizzen, Craig A.; Kelleher, Neil L.

    2007-01-01

    Post-translational modifications (PTMs) of histones are intimately involved in chromatin structure and thus have roles in cellular processes through their impact on gene activation or repression. At the forefront in histone PTM analysis are mass spectrometry-based techniques, which have capabilities to produce improved views of processes affected by chromatin remodeling via histone modifications. In this report, we take the first mass spectrometric look at histone variant expression and post-translational modifications from histones isolated from rat brain tissue. Analyses of whole rat brain identified specific histone H2A and H2B gene family members and several H4 and H3 post-translational modification sites by electron capture dissociation (ECD) mass spectrometry. We subsequently compared these results to selected rat brain regions. Major differences in the expression profiles of H2A and H2B gene family members or in the post-translational modifications on histone H4 were not observed from the different brain regions using a Top Down approach. However, "Middle Down" mass spectrometry facilitating improved characterization of the histone H3 tail (1-50 residues), revealed an enrichment of trimethylation on Lys9 from cerebellum tissue compared to H3 extracted from whole brain, cerebral cortex or hypothalamus tissue. We forward this study in honor of Professor Donald F. Hunt, whose pioneering efforts in protein and PTM analyses have spawned new eras and numerous careers, many exemplified in this special issue.

  9. Electron capture dissociation mass spectrometric analysis of lysine-phosphorylated peptides

    PubMed Central

    Kowalewska, Karolina; Stefanowicz, Piotr; Ruman, Tomasz; Frączyk, Tomasz; Rode, Wojciech; Szewczuk, Zbigniew

    2010-01-01

    Phosphorylation of proteins is an essential signalling mechanism in eukaryotic and prokaryotic cells. Although N-phosphorylation of basic amino acid is known for its importance in biological systems, it is still poorly explored in terms of products and mechanisms. In the present study, two MS fragmentation methods, ECD (electron-capture dissociation) and CID (collision-induced dissociation), were tested as tools for analysis of N-phosphorylation of three model peptides, RKRSRAE, RKRARKE and PLSRTLSVAAKK. The peptides were phosphorylated by reaction with monopotassium phosphoramidate. The results were confirmed by 1H NMR and 31P NMR studies. The ECD method was found useful for the localization of phosphorylation sites in unstable lysine-phosphorylated peptides. Its main advantage is a significant reduction of the neutral losses related to the phosphoramidate moiety. Moreover, the results indicate that the ECD–MS may be useful for analysis of regioselectivity of the N-phosphorylation reaction. Stabilities of the obtained lysine-phosphorylated peptides under various conditions were also tested. PMID:20144148

  10. Study of photon emission by electron capture during solar nuclei acceleration. 3: Photon production evaluations

    NASA Technical Reports Server (NTRS)

    Gallegos, A.; Perez-Peraza, J.; Alvarez, M.

    1985-01-01

    Lower limits of photon fluxes were evaluated from electron capture during acceleration in solar flares, because the arbitrary q sub c asterisk assumed in this work evolves very slow with velocity, probably much more slowly than the physical actual situation: in fact, more emission is expected toward the IR region. Nevertheless the authors claim to show that the factibility of sounding acceleration processes, charge evolution processes and physical parameters of the source itself, by the observational analysis of this kind of emissions. For instance, it would be interesting to search observationally, for the predicted flux and energy drift of F sub e ions interacting with the atomic 0 and F sub e of the source matter, or, even more feasible for the X-ray lines at 4.2 keV and 2.624 + 0.003 KeV from Fe and S ions in ionized Fe at T = 10 to the 7th power K respectively, the 418 + or - 2 eV and 20 + or - 4 eV lines of Fe and S in ionized Fe at 5 x 10 to the 6th power K, which are predicted from Fermi acceleration.

  11. Strong neutrino cooling by cycles of electron capture and decay in neutron star crusts

    SciTech Connect

    Schatz, Hendrik; Gupta, Sanjib; Moeller, Peter; Beard, Mary; Brown, Edward; Deibel, A. T.; Gasques, Leandro; Hix, William Raphael; Keek, Laurens; Lau, Rita; Steiner, Andrew M; Wiescher, Michael

    2013-01-01

    The temperature in the crust of an accreting neutron star, which comprises its outermost kilometre, is set by heating from nuclear reactions at large densities, neutrino cooling and heat transport from the interior. The heated crust has been thought to affect observable phenomena at shallower depths, such as thermonuclear bursts in the accreted envelope. Here we report that cycles of electron capture and its inverse, decay, involving neutron-rich nuclei at a typical depth of about 150 metres, cool the outer neutron star crust by emitting neutrinos while also thermally decoupling the surface layers from the deeper crust. This Urca mechanism has been studied in the context of white dwarfs13 and type Ia supernovae, but hitherto was not considered in neutron stars, because previous models1, 2 computed the crust reactions using a zero-temperature approximation and assumed that only a single nuclear species was present at any given depth. The thermal decoupling means that X-ray bursts and other surface phenomena are largely independent of the strength of deep crustal heating. The unexpectedly short recurrence times, of the order of years, observed for very energetic thermonuclear superbursts are therefore not an indicator of a hot crust, but may point instead to an unknown local heating mechanism near the neutron star surface.

  12. Electron-capture delayed fission properties of neutron-deficient einsteinium nuclei

    SciTech Connect

    Shaughnessy, Dawn A.

    2000-01-05

    Electron-capture delayed fission (ECDF) properties of neutron-deficient einsteinium isotopes were investigated using a combination of chemical separations and on-line radiation detection methods. {sup 242}Es was produced via the {sup 233}U({sup 14}N,5n){sup 242}Es reaction at a beam energy of 87 MeV (on target) in the lab system, and was found to decay with a half-life of 11 {+-} 3 seconds. The ECDF of {sup 242}Es showed a highly asymmetric mass distribution with an average pre-neutron emission total kinetic energy (TKE) of 183 {+-} 18 MeV. The probability of delayed fission (P{sub DF}) was measured to be 0.006 {+-} 0.002. In conjunction with this experiment, the excitation functions of the {sup 233}U({sup 14}N,xn){sup 247{minus}x}Es and {sup 233}U({sup 15}N,xn){sup 248{minus}x}Es reactions were measured for {sup 243}Es, {sup 244}Es and {sup 245}Es at projectile energies between 80 MeV and 100 MeV.

  13. Determination of sulfur dioxide in wine using headspace gas chromatography and electron capture detection.

    PubMed

    Aberl, A; Coelhan, M

    2013-01-01

    Sulfites are routinely added as preservatives and antioxidants in wine production. By law, the total sulfur dioxide content in wine is restricted and therefore must be monitored. Currently, the method of choice for determining the total content of sulfur dioxide in wine is the optimised Monier-Williams method, which is time consuming and laborious. The headspace gas chromatographic method described in this study offers a fast and reliable alternative method for the detection and quantification of the sulfur dioxide content in wine. The analysis was performed using an automatic headspace injection sampler, coupled with a gas chromatograph and an electron capture detector. The method is based on the formation of gaseous sulfur dioxide subsequent to acidification and heating of the sample. In addition to free sulfur dioxide, reversibly bound sulfur dioxide in carbonyl compounds, such as acetaldehyde, was also measured with this method. A total of 20 wine samples produced using diverse grape varieties and vintages of varied provenance were analysed using the new method. For reference and comparison purposes, 10 of the results obtained by the proposed method were compared with those acquired by the optimised Monier-Williams method. Overall, the results from the headspace analysis showed good correlation (R = 0.9985) when compared with the conventional method. This new method requires minimal sample preparation and is simple to perform, and the analysis can also be completed within a short period of time. PMID:23176364

  14. Rapidly evolving faint transients from stripped-envelope electron-capture supernovae

    NASA Astrophysics Data System (ADS)

    Moriya, Takashi J.; Eldridge, J. J.

    2016-09-01

    We investigate the expected rates and bolometric light-curve properties of stripped-envelope electron-capture supernovae (ECSNe) using stellar models from the Binary Population and Spectral Synthesis code. We find that 0.8 per cent (Z = 0.020) and 1.2 per cent (Z = 0.004) of core-collapse supernovae are stripped-envelope ECSNe. Their typical ejecta masses are estimated to be about 0.3 M⊙(Z = 0.020) and 0.6 M⊙ (Z = 0.004). Assuming ECSN explosion properties from numerical explosion simulations, an explosion energy of 1.5 × 1050 erg and a 56Ni mass of 2.5 × 10-3 M⊙, we find that stripped-envelope ECSNe have a typical rise time of around 7 d (Z = 0.020) or 13 d (Z = 0.004) and peak luminosity of around 1041 ergs-1 (-13.8 mag, Z = 0.020) or 7 × 1040 erg s-1 (-13.4 mag, Z = 0.004). Their typical ejecta velocities are around 7000 km s-1 (Z = 0.020) or 5000 km s-1 (Z = 0.004). Thus, stripped-envelope ECSNe are observed as rapidly evolving faint transients with relatively small velocities. SN 2008ha-like supernovae, which are the faintest kind of SN 2002cx-like (also known as Type Iax) supernovae, may be related to stripped-envelope ECSNe.

  15. Trace analysis of sulfamethazine in animal feed, human urine, and wastewater by electron capture gas chromatography

    SciTech Connect

    Holder, C.L.; Thompson, H.C. Jr.; Bowman, M.C.

    1981-12-01

    Sulfamethazine, a widely used antibacterial drug additive in feeds for swine, chickens, and cattle, was scheduled for toxicological evaluation because of potential human health hazards associated with its residues in edible animal tissues. Analytical chemical procedures that would ensure proper concentration, homogeneity, and stability of the drug in dosed feed and its safe usage during the animal studies were prerequisites for such toxicological tests. Electron capture gas chromatographic (EC/GC) methods were therefore devised for the analysis of sulfamethazine residues in animal feed, human urine, and wastewater at levels as low as 100, 10, and 10 ppb, respectively. Sample extracts were cleaned up by using liquid/liquid partitioning, and the extracts were subjected to two derivatizations followed by cleanup on a silica gel column. The derivatizations of sulfamethazine consisted of methylation followed by trifluoroacetylation of the primary amine function. Ancillary data concerning stability of the compound in animal feed, water, and as a dry residue on glass, extraction efficiencies, partition values with various solvents, and the analysis of residues in feed by high pressure liquid chromatography (HPLC) at levels as low as 1.0 ppm are presented.

  16. Optimized Electron-spin-cavity coupling in a double quantum dot

    NASA Astrophysics Data System (ADS)

    Hu, Xuedong; Liu, Yu-Xi; Nori, Franco

    2011-03-01

    We search for the optimal regime to couple an electron spin in a semiconductor double quantum dot to a superconducting stripline resonator via the electrically driven spin resonance technique. In particular, we calculate the spin relaxation rate in the regime when spin-photon coupling is strong, so that we can identify system parameters that allow the electron spin to reach the strong coupling limit. We thank support by NSA/LPS through ARO.

  17. Two-electron time-delay interference in atomic double ionization by attosecond pulses

    SciTech Connect

    Rescigno, Thomas N

    2009-10-04

    A two-color two-photon atomic double ionization experiment using subfemtosecond UV pulses can be designed such that the sequential two-color process dominates and one electron is ejected by each pulse. Nonetheless, ab initio calculations show that, for sufficiently short pulses, a prominent interference pattern in the joint energy distribution of the sequentially ejected electrons can be observed that is due to their indistinguishability and the exchange symmetry of the wave function.

  18. Two-Electron Time-Delay Interference in Atomic Double Ionization by Attosecond Pulses

    SciTech Connect

    Palacios, A.; Rescigno, T. N.; McCurdy, C. W.

    2009-12-18

    A two-color two-photon atomic double ionization experiment using subfemtosecond uv pulses can be designed such that the sequential two-color process dominates and one electron is ejected by each pulse. Nonetheless, ab initio calculations show that, for sufficiently short pulses, a prominent interference pattern in the joint energy distribution of the sequentially ejected electrons can be observed that is due to their indistinguishability and the exchange symmetry of the wave function.

  19. Pulsed Electron Double Resonance in Structural Studies of Spin-Labeled Nucleic Acids

    PubMed Central

    Fedorova, O. S.; Tsvetkov, Yu. D.

    2013-01-01

    This review deals with the application of the pulsed electron double resonance (PELDOR) method to studies of spin-labeled DNA and RNA with complicated spatial structures, such as tetramers, aptamers, riboswitches, and three- and four-way junctions. The use of this method for studying DNA damage sites is also described. PMID:23556128

  20. A tetrastable naphthalenediimide: anion induced charge transfer, single and double electron transfer for combinational logic gates.

    PubMed

    Ajayakumar, M R; Hundal, Geeta; Mukhopadhyay, Pritam

    2013-09-11

    Herein we demonstrate the formation of the first tetrastable naphthalenediimide (NDI, 1a) molecule having multiple distinctly readable outputs. Differential response of 1a to fluoride anions induces intramolecular charge transfer (ICT), single/double electron transfer (SET/DET) leading to a set of combinational logic gates for the first time with a NDI moiety. PMID:23752683

  1. Spectroscopy of molecular states in a few-electron double quantum dot

    NASA Astrophysics Data System (ADS)

    Hüttel, A. K.; Ludwig, S.; Eberl, K.; Kotthaus, J. P.

    2006-12-01

    Semiconductor quantum dots, so-called artificial atoms, have attracted considerable interest as mesoscopic model systems and prospective building blocks of the “quantum computer”. Electrons are trapped locally in quantum dots, forming controllable and coherent mesoscopic atom- and moleculelike systems. Electrostatic definition of quantum dots by use of top gates on a GaAs/AlGaAs heterostructure allows wide variation of the potential in the underlying two-dimensional electron gas. By distorting the trapping potential of a single quantum dot, a strongly tunnel-coupled double quantum dot can be defined. Transport spectroscopy measurements on such a system charged with N=0,1,2,… electrons are presented. In particular, the tunnel splitting of the double well potential for up to one trapped electron is unambiguously identified. It becomes visible as a pronounced level anticrossing at finite source drain voltage. A magnetic field perpendicular to the two-dimensional electron gas also modulates the orbital excitation energies in each individual dot. By tuning the asymmetry of the double well potential at finite magnetic field the chemical potentials of an excited state of one of the quantum dots and the ground state of the other quantum dot can be aligned, resulting in a second level anticrossing with a larger tunnel splitting. In addition, data on the two-electron transport spectrum are presented.

  2. Double-probe potential measurements near the Spacelab 2 electron beam

    NASA Technical Reports Server (NTRS)

    Steinberg, J. T.; Gurnett, D. A.; Banks, P. M.; Raitt, W. J.

    1988-01-01

    As part of the Spacelab 2 mission the plasma diagnostics package (PDP) was released from the shuttle as a free-flying satellite. The PDP carried a quasi-static electric field instrument which made differential voltage measurements between two floating probes. At various times during the free flight, an electron beam was ejected from the shuttle. Large differential voltages between the double probes were recorded in association with the electron beam. However, analysis indicates that these large signals are probably not caused by ambient electric fields. Instead, they can be explained by considering three effects: shadowing of the probes from streaming electrons by the PDP chassis, crossing of the PDP wake by the probes, and spatial gradients in the fluxes of energetic electrons reaching the probes. Plasma measurements on the PDP show that energetic electrons exist in a region 20 m wide and up to at least 170 m downstream from the electron beam. At 80 or more meters downstream from the beam, the double probe measurements show that the energetic electron flux is opposite to the injection direction, as would be expected for a secondary returning electron beam produced by scattering of the primary electron beam.

  3. Measuring θ13 in the Double Chooz experiment

    NASA Astrophysics Data System (ADS)

    Crum, Keith

    2013-04-01

    Double Chooz measures θ13 by searching for the disappearance of reactor electron antineutrinos (νe) interacting via inverse beta decay (IBD) in a liquid scintillator-based detector. The signature of IBD is the coincidence of positron annihilation followed by the capture of a neutron. Although Double Chooz was primarily designed to detect νe by searching for neutron capture on gadolinium, we can also search for neutron capture on hydrogen. We developed separate analyses for neutron capture on hydrogen and gadolinium as the two elements have different capture energies, capture lifetimes, and spatial distributions within our detector.

  4. Single-electron capture by low-energy Ar{sup q+} ions from He and Ne

    SciTech Connect

    Akgungor, K.; Kamber, E.Y.; Ferguson, S.M.

    1996-05-01

    State selective differential and total cross sections for single-electron capture processes by low-energy Ar{sup q+} (q = 4 - 8) ions from He and Ne targets have been studied experimentally at impact energies between 30 and 100 qeV, and laboratory scattering angles between 0{degrees} and 5{degrees}, by means of translational energy-gain spectroscopy. The ions were produced in a recoil ion source, pumped by a fast beam from the WMU Van de Graaff accelerator. The dominant processes are found to be single-electron capture (SEC) into the excited states of the projectile products. In additional to SEC, transfer excitation processes are also observed. It is found that the population of the dominant reaction channels is consistent with the predictions of the classical over-barrier model. The multichannel Landau-Zener (MCLZ) model has been used to obtain cross sections for capture into individual states. The MCLZ calculations are shown to be in good agreement with the measured energy-gain spectra. Total cross sections for single-electron capture are compared to the single-crossing Landau-Zener model, classical over-barrier model and available measurements. The general features of the angular distributions are discussed in terms of a semiclassical curve-crossing model.

  5. Electron correlation in two-photon double ionization of helium from attosecond to FEL pulses

    SciTech Connect

    Collins, Lee

    2009-01-01

    We investigate the role of electron correlation in the two-photon double ionization of helium for ultrashort pulses in the extreme ultraviolet (XUV) regime with durations ranging from a hundred attoseconds to a few femtoseconds. We perform time-dependent ab initio calculations for pulses with mean frequencies in the so-called 'sequential' regime ({Dirac_h}{omega} > 54.4 eV). Electron correlation induced by the time correlation between emission events manifests itself in the angular distribution of the ejected electrons, which strongly depends on the energy sharing between them. We show that for ultrashort pulses two-photon double ionization probabilities scale non-uniformly with pulse duration depending on the energy sharing between the electrons. Most interestingly we find evidence for an interference between direct ('nonsequential') and indirect ('sequential') double photoionization with intermediate shake-up states, the strength of which is controlled by the pulse duration. This observation may provide a route towards measuring the pulse duration of x-ray free-electron laser (XFEL) pulses.

  6. Research Electronic Data Capture (REDCap) - A metadata-driven methodology and workflow process for providing translational research informatics support

    PubMed Central

    Harris, Paul A.; Taylor, Robert; Thielke, Robert; Payne, Jonathon; Gonzalez, Nathaniel; Conde, Jose G.

    2009-01-01

    REDCap is a novel workflow methodology and software solution designed for rapid development and deployment of electronic data capture tools to support clinical and translational research. We present: 1) a brief description of the REDCap metadata-driven software toolset; 2) detail concerning the capture and use of study-related metadata from scientific research teams; 3) measures of impact for REDCap; 4) details concerning a consortium network of domestic and international institutions collaborating on the project; and 5) strengths and limitations of the REDCap system. REDCap is currently supporting 286 translational research projects in a growing collaborative network including 27 active partner institutions. PMID:18929686

  7. In this medium close-up view, captured by an Electronic Still Camera (ESC), the Spartan 207

    NASA Technical Reports Server (NTRS)

    1996-01-01

    STS-77 ESC VIEW --- In this medium close-up view, captured by an Electronic Still Camera (ESC), the Spartan 207 free-flyer is held in the grasp of the Space Shuttle Endeavour's Remote Manipulator System (RMS) following its re-capture on May 21, 1996. The six-member crew has spent a portion of the early stages of the mission in various activities involving the Spartan 207 and the related Inflatable Antenna Experiment (IAE). The Spartan project is managed by NASA's Goddard Space Flight Center (GSFC) for NASA's Office of Space Science, Washington, D.C. GMT: 09:38:05.

  8. Few-electron physics in Double quantum dots in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    von Stecher, Javier; Wunsch, Bernhard; Lukin, Mikahil; Demler, Eugene; Rey, Ana Maria

    2010-03-01

    Recent experimental progress on few-electron quantum dots (also known as artificial atoms) has allowed the controllable manipulation of the spin degrees of freedom of the confined electrons. Such control is at the heart of semiconductor-based spintronics and quantum-information proposals. Double-well quantum dot in semiconducting carbon nanotubes exhibit rich physics due to the additional valley degree of freedom. Here, we study the few-electron spectrum of a carbon-nanotube double quantum dot with spin-orbit coupling. We find that Coulomb interactions can cause strong correlation effects which lead to different ground state transitions. In particular, we show that such strong correlations can produce the disappearance of the Pauli blockade in transport experiments and an interaction-induced ferromagnetic ground state.

  9. Tandem-structured, hot electron based photovoltaic cell with double Schottky barriers

    PubMed Central

    Lee, Young Keun; Lee, Hyosun; Park, Jeong Young

    2014-01-01

    We demonstrate a tandem-structured, hot electron based photovoltaic cell with double Schottky barriers. The tandem-structured, hot electron based photovoltaic cell is composed of two metal/semiconductor interfaces. Two types of tandem cells were fabricated using TiO2/Au/Si and TiO2/Au/TiO2, and photocurrent enhancement was detected. The double Schottky barriers lead to an additional pathway for harvesting hot electrons, which is enhanced through multiple reflections between the two barriers with different energy ranges. In addition, light absorption is improved by the band-to-band excitation of both semiconductors with different band gaps. Short-circuit current and energy conversion efficiency of the tandem-structured TiO2/Au/Si increased by 86% and 70%, respectively, compared with Au/Si metal/semiconductor nanodiodes, showing an overall solar energy conversion efficiency of 5.3%. PMID:24694838

  10. Inner-shell electron effects in strong-field double ionization of Xe

    NASA Astrophysics Data System (ADS)

    Yuan, Zongqiang; Ye, Difa; Liu, Jie; Fu, Libin

    2016-06-01

    We investigate theoretically the inner-shell electron effects in strong-field double ionization of Xe by a comparative study with two different three-dimensional semiclassical models, i.e., the widely used helium-like model and an improved Green-Sellin-Zachor (GSZ) model. The enhanced double-ionization signals through sequential ionization and recollision-induced excitation with subsequent field ionization are identified as two origins of the nonstructured pattern in the correlated electron momentum spectrum observed in a recent experiment [Phys. Rev. Lett. 113, 103001 (2014), 10.1103/PhysRevLett.113.103001]. The relationship between these enhancements and the inner-shell electrons is revealed by back analysis of the classical trajectories.

  11. Hedgehog excitations in double-exchange magnetism: Energetics and electronic structure

    NASA Astrophysics Data System (ADS)

    Pekker, David; Goldbart, Paul; Salamon, Myron; Abanov, Alexander

    2004-03-01

    Topological hedgehog excitations of the magnetic state are believed to play an important role in the three-dimensional ferromagnet-to-paramagnet phase transition. This is true not only in Heisenberg magnets but also in double-exchange magnets, for which the transition is accompanied by a metal-insulator transition. The energetics and electronic structure of hedgehog excitations in double-exchange systems are investigated using a model in which the electrons move through a lattice of classical spins, to which they are coupled via Hund's Rule interactions. The core energy of hedgehog excitations is determined, as is the extent to which charge is expelled from the hedgehog cores. In settings involving pairs of hedgehogs, the manner in which the electronic energetics determines the magnetic structure is explored variationally, especially in the region between the hedgehogs.

  12. Fast coherent manipulation of three-electron states in a double quantum dot

    NASA Astrophysics Data System (ADS)

    Shi, Zhan; Simmons, C. B.; Ward, Daniel R.; Prance, J. R.; Wu, Xian; Koh, Teck Seng; Gamble, John King; Savage, D. E.; Lagally, M. G.; Friesen, Mark; Coppersmith, S. N.; Eriksson, M. A.

    2014-01-01

    An important goal in the manipulation of quantum systems is the achievement of many coherent oscillations within the characteristic dephasing time T2*. Most manipulations of electron spins in quantum dots have focused on the construction and control of two-state quantum systems, or qubits, in which each quantum dot is occupied by a single electron. Here we perform quantum manipulations on a system with three electrons per double quantum dot. We demonstrate that tailored pulse sequences can be used to induce coherent rotations between three-electron quantum states. Certain pulse sequences yield coherent oscillations fast enough that more than 100 oscillations are visible within a T2* time. The minimum oscillation frequency we observe is faster than 5 GHz. The presence of the third electron enables very fast rotations to all possible states, in contrast to the case when only two electrons are used, in which some rotations are slow.

  13. Entropy, fidelity, and double orthogonality for resonance states in two-electron quantum dots

    SciTech Connect

    Pont, Federico M.; Osenda, Omar; Serra, Pablo; Toloza, Julio H.

    2010-04-15

    Resonance states of a two-electron quantum dots are studied using a variational expansion with both real basis-set functions and complex scaling methods. The two-electron entanglement (linear entropy) is calculated as a function of the electron repulsion at both sides of the critical value, where the ground (bound) state becomes a resonance (unbound) state. The linear entropy and fidelity and double orthogonality functions are compared as methods for the determination of the real part of the energy of a resonance. The complex linear entropy of a resonance state is introduced using complex scaling formalism.

  14. Probing Electron Correlation via Attosecond xuv Pulses in the Two-Photon Double Ionization of Helium

    SciTech Connect

    Feist, J.; Nagele, S.; Pazourek, R.; Persson, E.; Burgdoerfer, J.; Schneider, B. I.; Collins, L. A.

    2009-08-07

    Recent experimental developments of high-intensity, short-pulse extreme ultraviolet light sources are enhancing our ability to study electron-electron correlations. We perform time-dependent calculations to investigate the so-called 'sequential' regime ((Planck constant/2pi)omega>54.4 eV) in the two-photon double ionization of helium. We show that attosecond pulses allow us not only to probe but also to induce angular and energy correlations of the emitted electrons. The final momentum distribution reveals regions dominated by the Wannier ridge breakup scenario and by postcollision interaction.

  15. First operation of a dielectric-loaded double-stripline free-electron maser experiment

    SciTech Connect

    Einat, M.; Jerby, E.; Shahadi, A.

    1995-12-31

    A tabletop free-electron maser (FEM) experiment based on a dielectric-loaded double-stripline waveguide is presented. It employs a low-energy (8 keV, 0.5 A) electron beam and a folded-foil wiggler ({lambda}w = 2 cm). Metal striplines protects the dielectric slabs from the electron beam and support quasi-TEM modes in the waveguide. Radiation output is observed at f = 3.5 GHz, in agreement with the dielectric-loaded FEM tuning relation.

  16. Shifts in electron capture to the continuum at low collision energies: Enhanced role of target postcollision interactions

    SciTech Connect

    Shah, M. B.; McGrath, C.; Luna, H.; Crothers, D.S.F.; O'Rourke, S.F.C.; Gilbody, H.B.; Illescas, Clara; Riera, A.; Pons, B.

    2003-01-01

    Measurements of electron velocity distributions emitted at 0 deg. for collisions of 10- and 20-keV H{sup +} incident ions on H{sub 2} and He show that the electron capture to the continuum cusp formation, which is still possible at these low impact energies, is shifted to lower momenta than its standard position (centered on the projectile velocity), as recently predicted. Classical trajectory Monte Carlo calculations reproduce the observations remarkably well, and indicate that a long-range residual interaction of the electron with the target ion after ionization is responsible for the shifts, which is a general effect that is enhanced at low nuclear velocities.

  17. Atypical behavior in the electron capture induced dissociation of biologically relevant transition metal ion complexes of the peptide hormone oxytocin

    NASA Astrophysics Data System (ADS)

    Kleinnijenhuis, Anne J.; Mihalca, Romulus; Heeren, Ron M. A.; Heck, Albert J. R.

    2006-07-01

    Doubly protonated ions of the disulfide bond containing nonapeptide hormone oxytocin and oxytocin complexes with different transition metal ions, that have biological relevance under physiological conditions, were subjected to electron capture dissociation (ECD) to probe their structural features in the gas phase. Although, all the ECD spectra were strikingly different, typical ECD behavior was observed for complexes of the nonapeptide hormone oxytocin with Ni2+, Co2+ and Zn2+, i.e., abundant c/z' and a'/y backbone cleavages and ECD characteristic S-S and S-C bond cleavages were observed. We propose that, although in the oxytocin-transition metal ion complexes the metal ions serve as the main initial capture site, the captured electron is transferred to other sites in the complex to form a hydrogen radical, which drives the subsequent typical ECD fragmentations. The complex of oxytocin with Cu2+ displayed noticeably different ECD behavior. The fragment ions were similar to fragment ions typically observed with low-energy collision induced dissociation (CID). We propose that the electrons captured by the oxytocin-Cu2+ complex might be favorably involved in reducing the Cu2+ metal ion to Cu+. Subsequent energy redistribution would explain the observed low-energy CID-type fragmentations. Electron capture resulted also in quite different specific cleavage sites for the complexes of oxytocin with Ni2+, Co2+ and Zn2+. This is an indication for structural differences in these complexes possibly linked to their significantly different biological effects on oxytocin-receptor binding, and suggests that ECD may be used to study subtle structural differences in transition metal ion-peptide complexes.

  18. Determination of methyl bromide in foods by headspace capillary gas chromatography with electron capture detection.

    PubMed

    Page, B D; Avon, R J

    1989-01-01

    Methyl bromide (MB, bromomethane) is determined in a variety of foods by headspace capillary gas chromatography with electron capture detection. The comminuted food sample as an aqueous sodium sulfate slurry is equilibrated with stirring for 1 h at room temperature before a 1 mL headspace aliquot is removed and injected using a modified on-column syringe needle. Methyl bromide is cryogenically focussed at -60 degrees C and then eluted by temperature programming. The procedure requires blending of soft samples, e.g. raisins, prunes, or oranges, and ultrasonic homogenization of hard samples, e.g. wheat, cocoa beans, corn, or nuts, with portions of water and ice so the final temperature of the food-water slurry is less than 1 degree C. A 20 g aliquot (4 g food) is then added to a cold headspace vial containing 4 g sodium sulfate. Losses of MB during a 3.5 min ultrasonic homogenization of wheat were 11% at 0.95 ppb and 4.4% at 4.8 ppb. For flour, cocoa, and finely divided spices, which do not require blending, 4 g is added to the cold headspace vial containing 16 mL cold water and 4 g sodium sulfate. Studies show that comminution of wheat or peanuts must be carried out to release MB trapped within the food so the headspace equilibrium can be attained in 1 h as well as to obtain homogeneous samples and representative sampling. No interferences were noted with the above foods or with many grain-based baking mixes analyzed.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2808244

  19. Electron-capture supernovae of super-asymptotic giant branch stars and the Crab supernova 1054

    SciTech Connect

    Nomoto, Ken'ichi; Tominaga, Nozomu; Blinnikov, Sergei I.

    2014-05-02

    An electron-capture supernova (ECSN) is a core-collapse supernova explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass M{sub Ms} ∼ 7 - 9.5M{sub ⊙}. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curves of a core-collapse supernova. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 × 10{sup 50} erg and the small {sup 56}Ni mass of 2.5 × 10{sup −3} M{sub ⊙}, we perform a multigroup radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope mass and hydrogen abundance. We demonstrate that a shock breakout has peak luminosity of L ∼ 2 × 10{sup 44} erg s{sup −1} and can evaporate circumstellar dust up to R ∼ 10{sup 17} cm for a case of carbon dust, that plateau luminosity and plateau duration of ECSNe are L ∼ 10{sup 42} erg s{sup −1} and {sup t} ∼ 60 - 100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by ∼ 4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires a ECSN model with a significantly low explosion energy of E ∼ 10{sup 48} erg.

  20. Electron-capture supernovae of super-asymptotic giant branch stars and the Crab supernova 1054

    NASA Astrophysics Data System (ADS)

    Nomoto, Ken'ichi; Tominaga, Nozomu; Blinnikov, Sergei I.

    2014-05-01

    An electron-capture supernova (ECSN) is a core-collapse supernova explosion of a super-asymptotic giant branch (SAGB) star with a main-sequence mass MMs ˜ 7 - 9.5M⊙. The explosion takes place in accordance with core bounce and subsequent neutrino heating and is a unique example successfully produced by first-principle simulations. This allows us to derive a first self-consistent multicolor light curves of a core-collapse supernova. Adopting the explosion properties derived by the first-principle simulation, i.e., the low explosion energy of 1.5 × 1050 erg and the small 56Ni mass of 2.5 × 10-3 M⊙, we perform a multigroup radiation hydrodynamics calculation of ECSNe and present multicolor light curves of ECSNe of SAGB stars with various envelope mass and hydrogen abundance. We demonstrate that a shock breakout has peak luminosity of L ˜ 2 × 1044 erg s-1 and can evaporate circumstellar dust up to R ˜ 1017 cm for a case of carbon dust, that plateau luminosity and plateau duration of ECSNe are L ˜ 1042 erg s-1 and t ˜ 60 - 100 days, respectively, and that a plateau is followed by a tail with a luminosity drop by ˜ 4 mag. The ECSN shows a bright and short plateau that is as bright as typical Type II plateau supernovae, and a faint tail that might be influenced by spin-down luminosity of a newborn pulsar. Furthermore, the theoretical models are compared with ECSN candidates: SN 1054 and SN 2008S. We find that SN 1054 shares the characteristics of the ECSNe. For SN 2008S, we find that its faint plateau requires a ECSN model with a significantly low explosion energy of E ˜ 1048 erg.

  1. Development of an Electronic Research Permissions Management System to Enhance Informed Consents and Capture Research Authorizations Data

    PubMed Central

    Obeid, Jihad S.; Gerken, Katherine; Madathil, Kapil Chalil; Rugg, Daniel; Alstad, Colin E.; Fryar, Katrina; Alexander, Randall; Gramopadhye, Anand K.; Moskowitz, Jay; Sanderson, Iain C.

    Informed consents are a critical and essential component of the clinical research process. Currently, most consents and research privacy authorizations are being captured on paper. In this paper we describe a novel method of capturing this information electronically. The objective is to allow easier tracking of research participants’ intent for current and future research involvement, enhance consent comprehension and facilitate the research workflow. After multidisciplinary analysis in key hospital registration areas and research participant enrollment, an open source software product was designed to capture this data through a user-friendly touch screen interface. The data may then be fed into a clinical data warehouse for use in cohort discovery or consent tracking. Despite ethical, legal and informatics challenges in clinical and research environments, we propose that this technology opens new avenues for significantly enhancing the consent process and positively impacting recruitment. PMID:24303263

  2. Spin conservation in single-electron capture by N[sup 2+] in He, Ne, and Ar

    SciTech Connect

    Lee, A.R. ); Wilkins, A.C.R.; Enos, C.S.; Brenton, A.G. )

    1993-10-01

    High-resolution translational energy spectra (0.2 eV at full width at half maximum) have been obtained for single-electron capture by 4-keV N[sup 2+] ions in collision with He, Ne, and Ar. Seven capture channels have been unambiguously identified for each of the He and Ne spectra, many of which have not been previously reported. This allows clarification of earlier studies. Twelve reaction channels have been identified for capture by N[sup 2+] in Ar, three of which involve excitation of the target product Ar[sup +] ion. All the observed channels are spin conservative. Competing channels which violate spin conservation are seen to be rigorously suppressed.

  3. The Role of Superthermal Electrons in the Formation of Double Layers and their Application in Space Plasmas

    NASA Astrophysics Data System (ADS)

    Singh, N.

    2014-12-01

    It is now widely recognized that superthermal electrons commonly exist with the thermal population in most space plasmas. When plasmas consisting of such electron population expand, double layers (DLs) naturally forma due to charge separation; the more mobile superthermal electrons march ahead of the thermal population, leaving a positive charge behind and generating electric fields. Under certain conditions such fields evolve into thin double layers or shocks. The double layers accelerate ions. Such double-layer formation was first invoked to explain expansion of laser produced plasmas. Since then it has been studied in laboratory experiments, and applied to (i) polar wind acceleration,(ii) the existence of low-altitude double layers in the auroral acceleration, (iii) a possible mechanism for the origination of the solar wind, (iv) the helicon double layer thrusters, and (v) the deceleration of electrons after their acceleration in solar flare events. The role of superthermal-electron driven double layers, also known as the low-altitude auroral double layers in the upward current region, in the upward acceleration of ionospheric ions is well-known. In the auroral application the upward moving superthermal electrons consist of backscattered downgoing primary energetic electrons as well as the secondary electrons. Similarly we suggest that such double layers might play roles in the acceleration of ions in the solar wind across the coronal transition region, where the superthermal electrons are supplied by magnetic reconnection events. We will present a unified theoretical view of the superthermal electron-driven double layers and their applications. We will summarize theoretical, experimental, simulation and observational results highlighting the common threads running through the various existing studies.

  4. Modification of magicity toward the dripline and its impact on electron-capture rates for stellar core collapse

    NASA Astrophysics Data System (ADS)

    Raduta, Ad. R.; Gulminelli, F.; Oertel, M.

    2016-02-01

    The importance of microphysical inputs from laboratory nuclear experiments and theoretical nuclear structure calculations in the understanding of core-collapse dynamics and the subsequent supernova explosion is largely recognized in the recent literature. In this work, we analyze the impact of the masses of very neutron-rich nuclei on the matter composition during collapse and the corresponding electron-capture rate. To this end, we introduce an empirical modification of the popular Duflo-Zuker mass model to account for possible shell quenching far from stability. We study the effect of this quenching on the average electron-capture rate. We show that the pre-eminence of the closed shells with N =50 and N =82 in the collapse dynamics is considerably decreased if the shell gaps are reduced in the region of 78Ni and beyond. As a consequence, local modifications of the overall electron-capture rate of up to 30% can be expected, depending on the strength of magicity quenching. This finding has potentially important consequences on the entropy generation, the neutrino emissivity, and the mass of the core at bounce. Our work underlines the importance of new experimental measurements in this region of the nuclear chart, the most crucial information being the nuclear mass and the Gamow-Teller strength. Reliable microscopic calculations of the associated elementary rate, in a wide range of temperatures and electron densities, optimized on these new empirical information, will be additionally needed to get quantitative predictions of the collapse dynamics.

  5. Low frequency solitons and double layers in a magnetized plasma with two temperature electrons

    SciTech Connect

    Rufai, O. R.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

    2012-12-15

    Finite amplitude non-linear ion-acoustic solitary waves and double layers are studied in a magnetized plasma with cold ions fluid and two distinct groups of Boltzmann electrons, using the Sagdeev pseudo-potential technique. The conditions under which the solitary waves and double layers can exist are found both analytically and numerically. We have shown the existence of negative potential solitary waves and double layers for subsonic Mach numbers, whereas in the unmagnetized plasma they can only in the supersonic Mach number regime. For the plasma parameters in the auroral region, the electric field amplitude of the solitary structures comes out to be 49 mV/m which is in agreement of the Viking observations in this region.

  6. On the bonding nature of electron states for the Fe-Mo double perovskite

    SciTech Connect

    Carvajal, E.; Cruz-Irisson, M.; Oviedo-Roa, R.; Navarro, O.

    2014-05-15

    The electronic transport as well as the effect of an external magnetic field has been investigated on manganese-based materials, spinels and perovskites. Potential applications of double perovskites go from magnetic sensors to electrodes in solid-oxide fuel cells; besides the practical interests, it is known that small changes in composition modify radically the physical properties of double perovskites. We have studied the Sr{sub 2}FeMoO{sub 6} double perovskite compound (SFMO) using first-principles density functional theory. The calculations were done within the generalized gradient approximation (GGA) scheme with the Perdew-Burke-Ernzerhof (PBE) functional. We have made a detailed analysis of each electronic state and the charge density maps around the Fermi level. For the electronic properties of SFMO it was used a primitive cell, for which we found the characteristic half-metallic behavior density of states composed by e{sub g} and t{sub 2g} electrons from Fe and Mo atoms. Those peaks were tagged as bonding or antibonding around the Fermi level at both, valence and conduction bands.

  7. Comparative analysis of the effects of electron and hole capture on the power characteristics of a semiconductor quantum-well laser

    SciTech Connect

    Sokolova, Z. N. Pikhtin, N. A.; Tarasov, I. S.; Asryan, L. V.

    2015-11-15

    The operating characteristics of a semiconductor quantum-well laser calculated using three models are compared. These models are (i) a model not taking into account differences between the electron and hole parameters and using the electron parameters for both types of charge carriers; (ii) a model, which does not take into account differences between the electron and hole parameters and uses the hole parameters for both types of charge carriers; and (iii) a model taking into account the asymmetry between the electron and hole parameters. It is shown that, at the same velocity of electron and hole capture into an unoccupied quantum well, the laser characteristics, obtained using the three models, differ considerably. These differences are due to a difference between the filling of the electron and hole subbands in a quantum well. The electron subband is more occupied than the hole subband. As a result, at the same velocities of electron and hole capture into an empty quantum well, the effective electron-capture velocity is lower than the effective hole-capture velocity. Specifically, it is shown that for the laser structure studied the hole-capture velocity of 5 × 10{sup 5} cm/s into an empty quantum well and the corresponding electron-capture velocity of 3 × 10{sup 6} cm/s into an empty quantum well describe the rapid capture of these carriers, at which the light–current characteristic of the laser remains virtually linear up to high pump-current densities. However, an electron-capture velocity of 5 × 10{sup 5} cm/s and a corresponding hole-capture velocity of 8.4 × 10{sup 4} cm/s describe the slow capture of these carriers, causing significant sublinearity in the light–current characteristic.

  8. Ion acceleration enhanced by additional neutralizing electrons in a magnetically expanding double layer plasma

    SciTech Connect

    Takahashi, Kazunori; Fujiwara, Tamiya

    2010-10-15

    Electrons neutralizing an ion beam are additionally supplied to a magnetically expanding double layer (DL) plasma from the downstream side of the DL. The rf power and the argon gas pressure are maintained at 200 W and 55 mPa, respectively, and the source magnetic field is varied in the range of about 70-550 G. It is observed that the ion beam energy corresponding to the DL potential drop increases up to 30 eV with an increase in the magnetic field when supplying the additional electrons, while it saturates at 20 eV for the case of the absence of the additional electrons. The supplied electrons are believed to be an energy source for the DL such that increasing the magnetic field is able to increase the potential drop beyond the limit found in the absence of the supplied electrons.

  9. Efficiency enhancement of planar perovskite solar cells by adding zwitterion/LiF double interlayers for electron collection

    NASA Astrophysics Data System (ADS)

    Sun, Kuan; Chang, Jingjing; Isikgor, Furkan Halis; Li, Pengcheng; Ouyang, Jianyong

    2014-12-01

    Double interlayers consisting of a zwitterionic small molecule layer and a LiF layer were introduced between the electron transport layer and the cathode of perovskite solar cells. The double interlayers improve the photovoltaic efficiency to 13.2%, which is higher than that of control devices without the double interlayer (9.2%) or with LiF (11.0%) or rhodamine 101 zwitterion (12.1%) alone.Double interlayers consisting of a zwitterionic small molecule layer and a LiF layer were introduced between the electron transport layer and the cathode of perovskite solar cells. The double interlayers improve the photovoltaic efficiency to 13.2%, which is higher than that of control devices without the double interlayer (9.2%) or with LiF (11.0%) or rhodamine 101 zwitterion (12.1%) alone. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05975a

  10. Spin-orbit induced two-electron spin relaxation in double quantum dots

    NASA Astrophysics Data System (ADS)

    Borhani, Massoud; Hu, Xuedong

    2011-03-01

    We study the spin decay of two electrons confined in a double quantum dots via the spin-orbit interaction and acoustic phonons. We have obtained a generic form for the spin Hamiltonian for two electrons confined in (elliptic) harmonic potentials in doubles dots and in the presence of an arbitrary applied magnetic field. Our focus is on the interdot bias regime where singlet-triplet splitting is small, in contrast to the spin-blockade regime. Our results clarify the spin-orbit mediated two-spin relaxation in lateral/nanowire quantum dots, particularly when the confining potentials are different in each dot. We thank support by NSA/LPS thorugh ARO.

  11. Ionization of xenon by electrons: Partial cross sections for single, double, and triple ionization

    SciTech Connect

    Mathur, D.; Badrinathan, C.

    1987-02-01

    High-sensitivity measurements of relative partial cross sections for single, double, and triple ionization of Xe by electron impact have been carried out in the energy region from threshold to 100 eV using a crossed-beam apparatus incorporating a quadrupole mass spectrometer. The weighted sum of the relative partial cross sections at 50 eV are normalized to the total ionization cross section of Rapp and Englander-Golden to yield absolute cross-section functions. Shapes of the partial cross sections for single and double ionization are difficult to account for within a single-particle picture. Comparison of the Xe/sup +/ data with 4d partial photoionization cross-section measurements indicates the important role played by many-body effects in describing electron-impact ionization of high-Z atoms.

  12. Nonlinear ion-acoustic double-layers in electronegative plasmas with electrons featuring Tsallis distribution

    NASA Astrophysics Data System (ADS)

    Ghebache, Siham; Tribeche, Mouloud

    2016-04-01

    Weakly nonlinear ion-acoustic (IA) double-layers (DLs), which accompany electronegative plasmas composed of positive ions, negative ions, and nonextensive electrons are investigated. A generalized Korteweg-de Vries equation with a cubic nonlinearity is derived using a reductive perturbation method. Different types of electronegative plasmas inspired from the experimental studies of Ichiki et al. (2001) are discussed. It is shown that the IA wave phase velocity, in different mixtures of negative and positive ions, decreases as the nonextensive parameter q increases, before levelling-off at a constant value for larger q. Moreover, a relative increase of Q involves an enhancement of the IA phase velocity. Existence domains of either solitary waves or double-layers are then presented and their parametric dependence is determined. Owing to the electron nonextensivity, our present plasma model can admit compressive as well as rarefactive IA-DLs.

  13. Double ionization of single oriented water molecules by electron impact: Second-order Born description

    SciTech Connect

    Dal Cappello, C.; Champion, C.; Kada, I.; Mansouri, A.

    2011-06-15

    The double ionization of isolated water molecules fixed in space is investigated within a theoretical approach based on the second-order Born approximation. Electron angular distributions have been studied for specific kinematical conditions. The three usual mechanisms, the shake-off and the two two-step mechanisms, have been identified. A significant contribution of the two-step mechanism is clearly visible for some particular kinematics.

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

    NASA Astrophysics Data System (ADS)

    Jones, Matthew Philip

    2011-12-01

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

  15. On the role of electron energy distribution function in double frequency heating of electron cyclotron resonance ion source plasmas

    SciTech Connect

    Schachter, L. Dobrescu, S.; Stiebing, K. E.

    2014-02-15

    Double frequency heating (DFH) is a tool to improve the output of highly charged ions particularly from modern electron cyclotron resonance ion source installations with very high RF-frequencies. In order to gain information on the DFH-mechanism and on the role of the lower injected frequency we have carried out a series of dedicated experiments where we have put emphasis on the creation of a discrete resonance surface also for this lower frequency. Our well-established method of inserting an emissive MD (metal-dielectric) liner into the plasma chamber of the source is used in these experiments as a tool of investigation. In this way, the electron temperature and density for both ECR zones is increased in a controlled manner, allowing conclusions on the role of the change of the electron-energy-distribution function with and without DFH.

  16. Coupling capacitance between double quantum dots tunable by the number of electrons in Si quantum dots

    SciTech Connect

    Uchida, Takafumi Arita, Masashi; Takahashi, Yasuo; Fujiwara, Akira

    2015-02-28

    Tunability of capacitive coupling in the Si double-quantum-dot system is discussed by changing the number of electrons in quantum dots (QDs), in which the QDs are fabricated using pattern-dependent oxidation (PADOX) of a Si nanowire and multi-fine-gate structure. A single QD formed by PADOX is divided into multiple QDs by additional oxidation through the gap between the fine gates. When the number of electrons occupying the QDs is large, the coupling capacitance increases gradually and almost monotonically with the number of electrons. This phenomenon is attributed to the gradual growth in the effective QD size due to the increase in the number of electrons in the QDs. On the other hand, when the number of electrons changes in the few-electron regime, the coupling capacitance irregularly changes. This irregularity can be observed even up to 40 electrons. This behavior is attributable the rough structure of Si nano-dots made by PADOX. This roughness is thought to induce complicated change in the electron wave function when an electron is added to or subtracted from a QD.

  17. Nonlinear response of metal nanoparticles: Double plasmon excitation and electron transfer.

    PubMed

    Gao, Shiwu

    2015-06-21

    We investigate the dynamical response of a metal nanoparticle and the electron transfer to a molecule near its surface using time-dependent density functional theory. In addition to the linear response of the Mie resonance, double plasmon excitations and a low-frequency charge transfer band emerge and become prominent at high laser intensities. Both modes are nonlinear processes, which are derived from the re-excitation and decay of the primary plasmon mode, respectively. Our results shed light on the localised characters of the plasmon-molecule coupling and hot electron distributions. These findings have general implications to photoinduced phenomena in nanosystems. PMID:26093567

  18. Nonlinear response of metal nanoparticles: Double plasmon excitation and electron transfer

    NASA Astrophysics Data System (ADS)

    Gao, Shiwu

    2015-06-01

    We investigate the dynamical response of a metal nanoparticle and the electron transfer to a molecule near its surface using time-dependent density functional theory. In addition to the linear response of the Mie resonance, double plasmon excitations and a low-frequency charge transfer band emerge and become prominent at high laser intensities. Both modes are nonlinear processes, which are derived from the re-excitation and decay of the primary plasmon mode, respectively. Our results shed light on the localised characters of the plasmon-molecule coupling and hot electron distributions. These findings have general implications to photoinduced phenomena in nanosystems.

  19. Electrostatic solitary wave and double layer in a plasma with heavy ions and nonthermally distributed electrons

    SciTech Connect

    Choi, C.-R.; Min, K.-W.; Woo, M.-H.; Ryu, C.-M.

    2010-09-15

    The existence condition for bump and dip type, as well as double layer (DL), solutions of electrostatic solitary waves (ESWs) in a nonthermal electron plasma with heavy ions is investigated by a pseudopotential method. It is found that the nonthermality of electrons determines the existence of the DL solution and that the amplitude of ESWs is enhanced by the density of heavy ions. When the heavy ion density is beyond a certain critical value, ESWs and DLs cannot exist. It is also found that both the lower and upper critical Mach numbers are reduced by the presence of heavy ions.

  20. Effect of spin-flip scattering on the electron transport through double quantum dots

    NASA Astrophysics Data System (ADS)

    Yang, Fu-Bin; Huang, Rui; Cheng, Yan

    2015-05-01

    We systematically investigate the electron transport through double quantum dots (DQD) with particular emphasis on the spin-flip scattering of an electron in the DQD. By means of the slave-boson mean-field approximation, we calculate the linear conductance and the transmission in the Kondo regime at zero temperature. The obtained results show that both the linear conductance and transmission probability are quite sensitive to the spin-flip strength when the DQD structure is changed among the serial, parallel and T-shaped. It is suggested that such a theoretical model can be used to study the physical phenomenon related to the spin manipulation transport.

  1. Nonlinear response of metal nanoparticles: Double plasmon excitation and electron transfer

    SciTech Connect

    Gao, Shiwu

    2015-06-21

    We investigate the dynamical response of a metal nanoparticle and the electron transfer to a molecule near its surface using time-dependent density functional theory. In addition to the linear response of the Mie resonance, double plasmon excitations and a low-frequency charge transfer band emerge and become prominent at high laser intensities. Both modes are nonlinear processes, which are derived from the re-excitation and decay of the primary plasmon mode, respectively. Our results shed light on the localised characters of the plasmon-molecule coupling and hot electron distributions. These findings have general implications to photoinduced phenomena in nanosystems.

  2. Cross sections for electron capture and excitation in collisions of Liq+ (q=1, 2, 3) with atomic hydrogen

    NASA Astrophysics Data System (ADS)

    Liu, L.; Li, X. Y.; Wang, J. G.; Janev, R. K.

    2014-06-01

    The two-center atomic orbital close-coupling method is employed to study electron capture and excitation reactions in collisions of Liq+ (q = 1-3) ions with ground state atomic hydrogen in the ion energy range from 0.1 keV/u to 300 keV/u, where u is the atomic mass unit. The interaction of the active electron with the projectile ions (Li+, Li2+) is represented by a model potential. Total and state-selective cross sections for charge transfer and excitation processes are calculated and compared with data from other sources when available.

  3. Comparative analysis of dioxins and furans in ambient air by high-resolution and electron-capture mass spectrometry

    SciTech Connect

    Koester, C.J.; Harless, R.L.; Hites, R.A.

    1992-01-01

    Known mixtures and unknown atmospheric sample extracts containing polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) were analyzed by both electron impact, high resolution, mass spectrometry (HRMS) and by electron capture, negative ion, low resolution mass spectrometry (ECNI). PCDD/F concentrations measured by the two methods were comparable, typically agreeing with + or - 33%. The major difference between the two techniques is that HRMS easily detects 2,3,7,8- tetrachlorodibenzo-p-dioxin but ECNI does not. Results suggest that ECNI can be a sensitive low cost alternative to HRMS for the determination of PCDD/F concentrations.

  4. Shock waves and double layers in a quantum electron-positron-ion plasma

    NASA Astrophysics Data System (ADS)

    Dip, P. R.; Hossen, M. A.; Salahuddin, M.; Mamun, A. A.

    2016-02-01

    The ion-acoustic (IA) shock waves and double layers (DLs) in an unmagnetized, dissipative, quantum electron-positron-ion (EPI) plasma (composed of a viscous heavy ion fluid, Fermi electrons and positrons) have been theoretically investigated. The higher-order Burgers and Gardner equations are derived by employing the reductive perturbation method. The basic features of the IA shock waves and the DLs are identified by analyzing the solutions of both the higher-order Burgers and Gardner equations. The ratio of the Fermi temperature of the positron to that of the electron, the Fermi pressure of electrons and positrons, the viscous force, the plasma particle number densities, etc. are found to change remarkably the basic features (viz. amplitude, width, phase speed, etc.) of the IA waves. The results of our investigation may be helpful in understanding the nonlinear features of localized IA waves propagating in quantum EPI plasmas which are ubiquitous in astrophysical, as well as laboratory, environments.

  5. Double-sided electron-beam generator for KrF laser excitation

    SciTech Connect

    Schlitt, L.; Swingle, J.

    1980-05-01

    Several laser systems excited by electron beam have been identified as candidates for pump sources for laser fusion applications. The electron beam generators required must be compact, reliable and capable of synchronization with other system components. A KrF laser producing a minimum output of 25 J was needed for the RAPIER (Raman Amplifier Pumped by Intensified Excimer Radiation) system. A double-sided electron beam system was designed and constructed specifically for this purpose and has produced > 35 J of KrF output. Each of the two electron beam machines in the system operates with an rms jitter of 0.4 ns and together occupy approx. 3.5 m/sup 2/ of floor space. The successful operation of this laser has engendered requests for a description of the engineering details of this system. This document contains a brief description of the design issues and a full set of engineering drawings for this KrF laser amplifier.

  6. Detection of single electron spin resonance in a double quantum dota)

    NASA Astrophysics Data System (ADS)

    Koppens, F. H. L.; Buizert, C.; Vink, I. T.; Nowack, K. C.; Meunier, T.; Kouwenhoven, L. P.; Vandersypen, L. M. K.

    2007-04-01

    Spin-dependent transport measurements through a double quantum dot are a valuable tool for detecting both the coherent evolution of the spin state of a single electron, as well as the hybridization of two-electron spin states. In this article, we discuss a model that describes the transport cycle in this regime, including the effects of an oscillating magnetic field (causing electron spin resonance) and the effective nuclear fields on the spin states in the two dots. We numerically calculate the current flow due to the induced spin flips via electron spin resonance, and we study the detector efficiency for a range of parameters. The experimental data are compared with the model and we find a reasonable agreement.

  7. Complete voltage recovery in quantum dot solar cells due to suppression of electron capture

    NASA Astrophysics Data System (ADS)

    Varghese, A.; Yakimov, M.; Tokranov, V.; Mitin, V.; Sablon, K.; Sergeev, A.; Oktyabrsky, S.

    2016-03-01

    Extensive investigations in recent years have shown that addition of quantum dots (QDs) to a single-junction solar cell decreases the open circuit voltage, VOC, with respect to the reference cell without QDs. Despite numerous efforts, the complete voltage recovery in QD cells has been demonstrated only at low temperatures. To minimize the VOC reduction, we propose and investigate a new approach that combines nanoscale engineering of the band structure and the potential profile. Our studies of GaAs solar cells with various InAs QD media demonstrate that the main cause of the VOC reduction is the fast capture of photoelectrons from the GaAs conduction band (CB) to the localized states in QDs. As the photoelectron capture into QDs is mainly realized via the wetting layers (WLs), we substantially reduced the WLs using two monolayer AlAs capping of QDs. In the structures with reduced WLs, the direct CB-to-QD capture is further suppressed due to charging of QDs via doping of the interdot space. The QD devices with suppressed photoelectron capture show the same VOC as the GaAs reference cell together with some improvements in the short circuit current.

  8. Complete voltage recovery in quantum dot solar cells due to suppression of electron capture.

    PubMed

    Varghese, A; Yakimov, M; Tokranov, V; Mitin, V; Sablon, K; Sergeev, A; Oktyabrsky, S

    2016-04-01

    Extensive investigations in recent years have shown that addition of quantum dots (QDs) to a single-junction solar cell decreases the open circuit voltage, VOC, with respect to the reference cell without QDs. Despite numerous efforts, the complete voltage recovery in QD cells has been demonstrated only at low temperatures. To minimize the VOC reduction, we propose and investigate a new approach that combines nanoscale engineering of the band structure and the potential profile. Our studies of GaAs solar cells with various InAs QD media demonstrate that the main cause of the VOC reduction is the fast capture of photoelectrons from the GaAs conduction band (CB) to the localized states in QDs. As the photoelectron capture into QDs is mainly realized via the wetting layers (WLs), we substantially reduced the WLs using two monolayer AlAs capping of QDs. In the structures with reduced WLs, the direct CB-to-QD capture is further suppressed due to charging of QDs via doping of the interdot space. The QD devices with suppressed photoelectron capture show the same VOC as the GaAs reference cell together with some improvements in the short circuit current. PMID:26974517

  9. Singlet-triplet electron spin qubit in Si/SiGe double quantum dot

    NASA Astrophysics Data System (ADS)

    Wu, Xian

    In this thesis, we study the electronic properties of devices made from Si/SiGe heterostructures and demonstrate universal control of a two-electron spin qubit in a double quantum dot. First, we introduce the basic concepts of a quantum bit (qubit), which is the fundamental building block of a quantum computer. We choose to use electron spin states in a solid state device as the hardware for implementing a qubit. The solid state device is made in a Si/SiGe heterostructure, in which a two dimensional electron gas (2DEG) forms at the interface of a Si layer and a SiGe layer at cryogenic temperatures. Metal gates are patterned on top of the heterostrucutres to confine electrons in the two lateral directions. We characterize the material by fabricating Hall bars and performing magnetotransport measurements on those Hall bars to extract the carrier density and mobility of the 2DEG formed in each material. We study the surface effects of modulation doped heterostructures on the 2DEG formed underneath and demonstrate that the quality of the surface affects the property of the buried 2DEG in a Si/SiGe heterostructure. In a double quantum dot, the spin singlet state and the spin-zero triplet state of two electrons can be used as the qubit basis states. The energy difference between singlet and triplet states induces rotations about the Z axis in the Bloch sphere. The difference in magnetic field DeltaB between the two sides of the double dot, arising from the coupling to the nuclear spins in the host material, drives singlet-triplet state rotation about the X axis in the Blochsphere. X rotation is poor because this nuclear Delta B is unstable. We fabricate a Si/SiGe double quantum dot with an integrated micromagnet, which generates a larger and more stable Delta B to improve X rotation. Using this DeltaB, we demonstrate coherent rotation of the qubit's Bloch vector about two different axes of the Bloch sphere. The inhomogeneous spin coherence time T 2* is determined. We

  10. Ion Acoustic Solitons and Double Layers in the Solar Wind Having Kappa Distributed Electrons

    NASA Astrophysics Data System (ADS)

    Lakhina, G. S.; Singh, S. V.

    2015-12-01

    It is shown that two types of, slow and fast, ion-acoustic solitary waves can occur in a solar wind plasma consisting of fluid hot protons, hot alpha particles streaming with respect to protons, and suprathermal electrons having k- distribution. The fast ion-acoustic mode is similar to the ion-acoustic mode of proton-electron plasma, and can support only positive potential solitons. The slow ion-acoustic mode is a new mode that occurs due to the presence of alpha particles. This mode can support both positive and negative solitons and double layers. The slow ion-acoustic mode can exist even when the relative streaming, U0, between alphas and protons is zero, provided alpha temperature, Ti, is not exactly equal to 4 times the proton temperature, Tp. An increase of the k- index leads to an increase in the critical Mach number, maximum Mach number and the maximum amplitude of both slow and fast ion-acoustic solitons. The model can explain the amplitudes and widths, but not shapes, of the weak double layers (WDLs) observed in the solar wind at 1 AU by Wind spacecraft in terms of slow ion-acoustic double layers. It is proposed that both slow and fast ion-acoustic solitons may be responsible for the ion- acoustic like wave activity in the solar wind.

  11. Capturing enveloped viruses on affinity grids for downstream cryo-electron microscopy applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electron microscopy cryo-electron microscopy and cryo-electron tomography are essential techniques used for characterizing basic virus morphology and determining the three-dimensional structure of viruses. Enveloped viruses, which contain an outer lipoprotein coat, constitute the largest group of pa...

  12. Lateral diffusion of lipid probes in the surface membrane of human platelets. An electron-electron double resonance (ELDOR) study.

    PubMed Central

    Lai, C S; Wirt, M D; Yin, J J; Froncisz, W; Feix, J B; Kunicki, T J; Hyde, J S

    1986-01-01

    Electron-electron double resonance (ELDOR) techniques employing [14N], [15N] 16-Doxylstearate spin-label pairs have been used to measure the lateral diffusion constant, D, of lipids in the surface membrane of intact human blood platelets. For freshly prepared platelets, D is 1.0 X 10(-8) cm2/s at 37 degrees C and for platelets stored for 3 d at room temperature under accepted routine blood bank conditions, D is 2.6 X 10(-8) cm2/s at 37 degrees C. This is the first time that D in the surface membrane of platelets is reported. The marked increase in D for stored platelets may be attributed at least partly to loss of cholesterol during storage, suggesting a correlation between lipid lateral diffusion and cholesterol levels in cell membranes. PMID:3019445

  13. The feasibility of using 'bring your own device' (BYOD) technology for electronic data capture in multicentre medical audit and research.

    PubMed

    Faulds, M C; Bauchmuller, K; Miller, D; Rosser, J H; Shuker, K; Wrench, I; Wilson, P; Mills, G H

    2016-01-01

    Large-scale audit and research projects demand robust, efficient systems for accurate data collection, handling and analysis. We utilised a multiplatform 'bring your own device' (BYOD) electronic data collection app to capture observational audit data on theatre efficiency across seven hospital Trusts in South Yorkshire in June-August 2013. None of the participating hospitals had a dedicated information governance policy for bring your own device. Data were collected by 17 investigators for 392 individual theatre lists, capturing 14,148 individual data points, 12, 852 (91%) of which were transmitted to a central database on the day of collection without any loss of data. BYOD technology enabled accurate collection of a large volume of secure data across multiple NHS organisations over a short period of time. Bring your own device technology provides a method for collecting real-time audit, research and quality improvement data within healthcare systems without compromising patient data protection. PMID:26526934

  14. Electron capture in very low energy collisions of multicharged ions with H and D in merged beams

    SciTech Connect

    Havener, C.C.; Meyer, F.W.; Phaneuf, R.A.

    1991-01-01

    An ion-atom merged-beams technique is being used to measure total absolute electron-capture cross sections for multicharged ions in collisions with H (or D) in the energy range between 0.1 and 1000 eV/amu. Comparison between experiment and theory over such a large energy range constitutes a critical test for both experiment and theory. Total capture cross-section measurements for O{sup 3+} H(D) and O{sup 5+} + H(D) are presented and compared to state selective and differential cross section calculations. Landau-Zener calculations show that for O{sup 5+} the sharp increase in the measured cross section below 1 eV/amu is partly due to trajectory effects arising from the ion-induced dipole interaction between the reactants. 20 refs., 8 figs.

  15. Measurements of the electron-impact double-to-single ionization ratio using trapped lithium

    NASA Astrophysics Data System (ADS)

    Huang, M.-T.; Zhang, L.; Hasegawa, S.; Southworth, S. H.; Young, L.

    2002-07-01

    The Li2+ to Li+ production cross-section ratio of ground-state atomic Li by electron-impact ionization has been measured for electron energies ranging from 200 eV to 1500 eV. The measurements were done using a pulsed, ion imaging time-of-flight spectrometer with Li atoms confined in a magneto-optical trap. The ratios are more accurate than the single earlier result for the Li2+ to Li+ ratios, a composite of two absolute measurements, and are systematically lower. Both experiments show similar energy dependences that disagree with the trend predicted by a semiempirical formulation. These measurements provide a benchmark for theoretical studies of electron-impact double ionization.

  16. Role of nonthermal electrons on dust ion acoustic double layer with variable dust charge

    NASA Astrophysics Data System (ADS)

    Borah, Prathana; Gogoi, Deepshikha; Das, Nilakshi

    2016-01-01

    The presence of nonthermal electron may play an important role in the formation of nonlinear structures in plasma. On the other hand, fluctuation of dust charge is an important and unique feature of complex plasma and it gives rise to a dissipative effect in the system leading to the formation of nonlinear structures due to the balance between nonlinearity and dissipation. In this paper, the propagation of nonlinear dust ion acoustic (DIA) wave in unmagnetized collisionless dusty plasma consisting of ions, nonthermal electrons and dust grains with variable negative charge has been investigated using the Sagdeev potential method. The existence domain of rarefactive double layer (DL) in the DIA wave has been investigated for the range of plasma parameters. The real potential has been obtained by numerically solving the Poisson equation and dust charging equation. It is observed that the presence of nonthermal electrons strengthens the DIA DL.

  17. Non uniform shrinkages of double-walled carbon nanotube as induced by electron beam irradiation

    SciTech Connect

    Zhu, Xianfang Li, Lunxiong; Gong, Huimin; Yang, Lan; Sun, Chenghua

    2014-09-01

    Electron beam-induced nanoinstabilities of pristine double-walled carbon nanotubes (DWCNTs) of two different configurations, one fixed at both ends and another fixed at only one end, were in-situ investigated in transmission electron microscope at room temperature. It was observed that the DWCNT fixed at both ends shrank in its diameter uniformly. Meanwhile, the DWCNT fixed at only one end intriguingly shrank preferentially from its free cap end along its axial direction whereas its diameter shrinkage was offset. A mechanism of “diffusion” along with “evaporation” at room temperature which is driven by the nanocurvature of the DWCNTs, and the athermal activation induced by the electron beam was proposed to elucidate the observed phenomena. The effect of the interlayer interaction of the DWCNTs was also discussed.

  18. A double-layer based model of ion confinement in electron cyclotron resonance ion source

    SciTech Connect

    Mascali, D. Neri, L.; Celona, L.; Castro, G.; Gammino, S.; Ciavola, G.; Torrisi, G.; Università Mediterranea di Reggio Calabria, Dipartimento di Ingegneria dell’Informazione, delle Infrastrutture e dell’Energia Sostenibile, Via Graziella, I-89100 Reggio Calabria ; Sorbello, G.; Università degli Studi di Catania, Dipartimento di Ingegneria Elettrica Elettronica ed Informatica, Viale Andrea Doria 6, 95125 Catania

    2014-02-15

    The paper proposes a new model of ion confinement in ECRIS, which can be easily generalized to any magnetic configuration characterized by closed magnetic surfaces. Traditionally, ion confinement in B-min configurations is ascribed to a negative potential dip due to superhot electrons, adiabatically confined by the magneto-static field. However, kinetic simulations including RF heating affected by cavity modes structures indicate that high energy electrons populate just a thin slab overlapping the ECR layer, while their density drops down of more than one order of magnitude outside. Ions, instead, diffuse across the electron layer due to their high collisionality. This is the proper physical condition to establish a double-layer (DL) configuration which self-consistently originates a potential barrier; this “barrier” confines the ions inside the plasma core surrounded by the ECR surface. The paper will describe a simplified ion confinement model based on plasma density non-homogeneity and DL formation.

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

    PubMed

    Yavuz, Murat; Ozer, Zehra Nur; Ulu, Melike; Champion, Christophe; Dogan, Mevlut

    2016-04-28

    Experimental and theoretical double differential cross sections (DDCSs) for electron-induced ionization of methane (CH4) are here reported for primary energies ranging from 50 eV to 350 eV and ejection angles between 25° and 130°. Experimental DDCSs are compared with theoretical predictions performed within the first Born approximation Coulomb wave. In this model, the initial molecular state is described by using single center wave functions, the incident (scattered) electron being described by a plane wave, while a Coulomb wave function is used for modeling the secondary ejected electron. A fairly good agreement may be observed between theory and experiment with nevertheless an expected systematic overestimation of the theory at low-ejection energies (<50 eV). PMID:27131548

  20. Frequency-doubled Alexandrite laser for use in periodontology: a scanning electron microscopic investigation

    NASA Astrophysics Data System (ADS)

    Rechmann, Peter; Hennig, Thomas

    1996-12-01

    During prior studies it could be demonstrated that engaging a frequency double Alexandrite-laser allows a fast and strictly selective ablation of supra- and subgingival calculus. Furthermore, the removal of unstained microbial plaque was observed. First conclusions were drawn following light microscopic investigations on undecalcified sections of irradiated teeth. In the present study the cementum surface after irradiation with a frequency doubled Alexandrite-laser was observed by means of a scanning electron microscope. After irradiation sections of teeth were dried in alcohol and sputtered with gold. In comparison irradiated cementum surfaces of unerupted operatively removed wisdom teeth and tooth surfaces after the selective removal of calculus were investigated. A complete removal of calculus was observed as well as a remaining smooth surface of irradiated cementum.

  1. Single-polaron properties for double-well electron-phonon coupling

    NASA Astrophysics Data System (ADS)

    Adolphs, Clemens; Berciu, Mona

    2014-03-01

    We introduce a new model to describe electron-phonon coupling in systems such as one-dimensional intercalated chains or two-dimensional CuO2 planes, where symmetry dictates that the linear coupling term vanishes. We show that, under certain conditions, an additional charge carrier dynamically changes the local lattice potential from a harmonic well into a double well. We use the Momentum Average approximation to study the properties of this model in the single-polaron limit. A detailed analysis reveals that despite some qualitative similarities to the linear Holstein model, a renormalized Holstein model cannot account for all of the physics of the double-well model. We thank NSERC and QMI for financial support.

  2. Energy and angle differential cross sections for the electron-impact double ionization of helium

    SciTech Connect

    Colgan, James P; Pindzola, M S; Robicheaux, F

    2008-01-01

    Energy and angle differential cross sections for the electron-impact double ionization of helium are calculated using a non-perturbative time-dependent close-coupling method. Collision probabilities are found by projection of a time evolved nine dimensional coordinate space wave function onto fully antisymmetric products of spatial and spin functions representing three outgoing Coulomb waves. At an incident energy of 106 eV, we present double energy differential cross sections and pentuple energy and angle differential cross sections. The pentuple energy and angle differential cross sections are found to be in relative agreement with the shapes observed in recent (e,3e) reaction microscope experiments. Integration of the differential cross sections over all energies and angles yields a total ionization cross section that is also in reasonable agreement with absolute crossed-beams experiments.

  3. Concerted Electronic and Nuclear Fluxes During Coherent Tunnelling in Asymmetric Double-Well Potentials.

    PubMed

    Bredtmann, Timm; Manz, Jörn; Zhao, Jian-Ming

    2016-05-19

    The quantum theory of concerted electronic and nuclear fluxes (CENFs) during coherent periodic tunnelling from reactants (R) to products (P) and back to R in molecules with asymmetric double-well potentials is developed. The results are deduced from the solution of the time-dependent Schrödinger equation as a coherent superposition of two eigenstates; here, these are the two states of the lowest tunnelling doublet. This allows the periodic time evolutions of the resulting electronic and nuclear probability densities (EPDs and NPDs) as well as the CENFs to be expressed in terms of simple sinusodial functions. These analytical results reveal various phenomena during coherent tunnelling in asymmetric double-well potentials, e.g., all EPDs and NPDs as well as all CENFs are synchronous. Distortion of the symmetric reference to a system with an asymmetric double-well potential breaks the spatial symmetry of the EPDs and NPDs, but, surprisingly, the symmetry of the CENFs is conserved. Exemplary application to the Cope rearrangement of semibullvalene shows that tunnelling of the ideal symmetric system can be suppressed by asymmetries induced by rather small external electric fields. The amplitude for the half tunnelling, half nontunnelling border is as low as 0.218 × 10(-8) V/cm. At the same time, the delocalized eigenstates of the symmetric reference, which can be regarded as Schrödinger's cat-type states representing R and P with equal probabilities, get localized at one or the other minima of the asymmetric double-well potential, representing either R or P. PMID:26799383

  4. Double-electron excitation of H- by fast proton and antiproton impact

    NASA Astrophysics Data System (ADS)

    Hino, Ken-Ichi; Nagase, Mamoru; Okamoto, Hiroyuki; Morishita, Toru; Matsuzawa, Michio; Kimura, Mineo

    1994-05-01

    A theoretical investigation is carried out for double-electron excitation processes of H- induced by proton and antiproton impact at the enegy of 1.5 MeV. Excitation cross sections to the 2s2 1Se, 2s2p 1Po, and 2p2 1De states are calculated by using the plane-wave Born approximation, the distorted-wave Born approximation, and the close-coupling method. Wave functions of H- are generated employing the hyperspherical coordinate method. It is shown that the low-lying continuum 1skp 1Po is identified as an important intermediate state in the double-electron excitation process to the 2p2 1De state. We have also evaluated the ejected-electron spectra from the 2s2p 1Po shape-resonance state. It is found that its spectral shape is close to the observed line profile of the photodetachment of H- since the excitation mechanism to this state is mostly dominated by the optically allowed transition at the projectile energy concerned here.

  5. All-electron topological insulator in InAs double wells

    NASA Astrophysics Data System (ADS)

    Erlingsson, Sigurdur I.; Egues, J. Carlos

    2015-01-01

    We show that electrons in ordinary III-V semiconductor double wells with an in-plane modulating periodic potential and interwell spin-orbit interaction are tunable topological insulators (TIs). Here the essential TI ingredients, namely, band inversion and the opening of an overall bulk gap in the spectrum arise, respectively, from (i) the combined effect of the double-well even-odd state splitting ΔSAS together with the superlattice potential and (ii) the interband Rashba spin-orbit coupling η . We corroborate our exact diagonalization results with an analytical nearly-free-electron description that allows us to derive an effective Bernevig-Hughes-Zhang model. Interestingly, the gate-tunable mass gap M drives a topological phase transition featuring a discontinuous Chern number at ΔSAS˜5.4 meV . Finally, we explicitly verify the bulk-edge correspondence by considering a strip configuration and determining not only the bulk bands in the nontopological and topological phases but also the edge states and their Dirac-like spectrum in the topological phase. The edge electronic densities exhibit peculiar spatial oscillations as they decay away into the bulk. For concreteness, we present our results for InAs-based wells with realistic parameters.

  6. Towards double-functionalized small diamondoids: selective electronic band-gap tuning

    NASA Astrophysics Data System (ADS)

    Adhikari, Bibek; Fyta, Maria

    2015-01-01

    Diamondoids are nanoscale diamond-like cage structures with hydrogen terminations, which can occur in various sizes and with a diverse type of modifications. In this work, we focus on the structural alterations and the effect of doping and functionalization on the electronic properties of diamondoids, from the smallest adamantane to heptamantane. The results are based on quantum mechanical calculations. We perform a self-consistent study, starting with doping the smallest diamondoid, adamantane. Boron, nitrogen, silicon, oxygen, and phosphorus are chosen as dopants at sites which have been previously optimized and are also consistent with the literature. At a next step, an amine- and a thiol- group are separately used to functionalize the adamantane molecule. We mainly focus on a double functionalization of diamondoids up to heptamantane using both these atomic groups. The effect of isomeration in the case of tetramantane is also studied. We discuss the higher efficiency of a double-functionalization compared to doping or a single-functionalization of diamondoids in tuning the electronic properties, such as the electronic band-gap, of modified small diamondoids in view of their novel nanotechnological applications.

  7. On the generation of double layers from ion- and electron-acoustic instabilities

    NASA Astrophysics Data System (ADS)

    Fu, Xiangrong; Cowee, Misa M.; Gary, S. Peter; Winske, Dan

    2016-03-01

    A plasma double layer (DL) is a nonlinear electrostatic structure that carries a uni-polar electric field parallel to the background magnetic field due to local charge separation. Past studies showed that DLs observed in space plasmas are mostly associated with the ion acoustic instability. Recent Van Allen Probes observations of parallel electric field structures traveling much faster than the ion acoustic speed have motivated a computational study to test the hypothesis that a new type of DLs—electron acoustic DLs—generated from the electron acoustic instability are responsible for these electric fields. Nonlinear particle-in-cell simulations yield negative results, i.e., the hypothetical electron acoustic DLs cannot be formed in a way similar to ion acoustic DLs. Linear theory analysis and the simulations show that the frequencies of electron acoustic waves are too high for ions to respond and maintain charge separation required by DLs. However, our results do show that local density perturbations in a two-electron-component plasma can result in unipolar-like electric field structures that propagate at the electron thermal speed, suggesting another potential explanation for the observations.

  8. Hybrid orbital and numerical grid representation for electronic continuum processes: Double photoionization of atomic beryllium

    SciTech Connect

    Yip, F. L.; Rescigno, T. N.; McCurdy, C. W.

    2010-05-15

    A general approach for ab initio calculations of electronic continuum processes is described in which the many-electron wave function is expanded using a combination of orbitals at short range and the finite-element discrete-variable representation (FEM-DVR) at larger distances. The orbital portion of the basis allows efficient construction of many-electron configurations in which some of the electrons are bound, but because the orbitals are constructed from an underlying FEM-DVR grid, the calculation of two-electron integrals retains the efficiency of the primitive FEM-DVR approach. As an example, double photoionization of beryllium is treated in a calculation in which the 1s{sup 2} core is frozen. This approach extends the use of exterior complex scaling (ECS), successfully applied to helium and H{sub 2}, to calculations with two active electrons on more complicated targets. Integrated, energy-differential and triply-differential cross sections are exhibited, and the results agree well with other theoretical investigations.

  9. Hybrid Orbital and Numerical Grid Representationfor Electronic Continuum Processes: Double Photoionization of Atomic Beryllium

    SciTech Connect

    Yip, Frank L; McCurdy, C. William; Rescigno, Thomas N

    2010-04-19

    A general approach for ab initio calculations of electronic continuum processes is described in which the many-electron wave function is expanded using a combination of orbitals at short range and the finite-element discrete variable representation(FEM-DVR) at larger distances. The orbital portion of the basis allows the efficient construction of many-electron configurations in which some of the electrons are bound, but because the orbitals are constructed from an underlying FEM-DVR grid, the calculation of two-electron integrals retains the efficiency of the primitive FEM-DVR approach. As an example, double photoionization of beryllium is treated in a calculation in which the 1s{sup 2} core is frozen. This approach extends the use of exterior complex scaling (ECS) successfully applied to helium and H{sub 2} to calculations with two active electrons on more complicated targets. Integrated, energy-differential and triply-differential cross sections are exhibited, and the results agree well with other theoretical investigations.

  10. Preparatory studies for a high-precision Penning-trap measurement of the 163Ho electron capture Q-value

    NASA Astrophysics Data System (ADS)

    Schneider, F.; Beyer, T.; Blaum, K.; Block, M.; Chenmarev, S.; Dorrer, H.; Düllmann, Ch. E.; Eberhardt, K.; Eibach, M.; Eliseev, S.; Grund, J.; Köster, U.; Nagy, Sz.; Novikov, Yu. N.; Renisch, D.; Türler, A.; Wendt, K.

    2015-07-01

    The ECHo Collaboration (Electron Capture 163Ho aims to investigate the calorimetric spectrum following the electron capture decay of 163Ho to determine the mass of the electron neutrino. The size of the neutrino mass is reflected in the endpoint region of the spectrum, i.e., the last few eV below the transition energy. To check for systematic uncertainties, an independent determination of this transition energy, the Q-value, is mandatory. Using the TRIGA-TRAP setup, we demonstrate the feasibility of performing this measurement by Penning-trap mass spectrometry. With the currently available, purified 163Ho sample and an improved laser ablation mini-RFQ ion source, we were able to perform direct mass measurements of 163Ho and 163Dy with a sample size of less than 1017 atoms. The measurements were carried out by determining the ratio of the cyclotron frequencies of the two isotopes to those of carbon cluster ions using the time-of-flight ion cyclotron resonance method. The obtained mass excess values are ME(163Ho)= -66379.3(9) keV and ME(163Dy)= -66381.7(8) keV. In addition, the Q-value was measured for the first time by Penning-trap mass spectrometry to be Q = 2.5(7) keV.

  11. Boron Neutron Capture Therapty (BNCT) in an Oral Precancer Model: Therapeutic Benefits and Potential Toxicity of a Double Application of BNCT with a Six-Week Interval

    SciTech Connect

    Andrea Monti Hughes; Emiliano C.C. Pozzi; Elisa M. Heber; Silvia Thorp; Marcelo Miller; Maria E. Itoiz; Romina F. Aromando; Ana J. Molinari; Marcela A. Garabalino; David W. Nigg; Veronica A. Trivillin; Amanda E. Schwint

    2011-11-01

    Given the clinical relevance of locoregional recurrences in head and neck cancer, we developed a novel experimental model of premalignant tissue in the hamster cheek pouch for long-term studies and demonstrated the partial inhibitory effect of a single application of Boron Neutron Capture Therapy (BNCT) on tumor development from premalignant tissue. The aim of the present study was to evaluate the effect of a double application of BNCT with a 6 week interval in terms of inhibitory effect on tumor development, toxicity and DNA synthesis. We performed a double application, 6 weeks apart, of (1) BNCT mediated by boronophenylalanine (BPA-BNCT); (2) BNCT mediated by the combined application of decahydrodecaborate (GB-10) and BPA [(GB-10 + BPA)-BNCT] or (3) beam-only, at RA-3 nuclear reactor and followed the animals for 8 months. The control group was cancerized and sham-irradiated. BPA-BNCT, (GB- 10 + BPA)-BNCT and beam-only induced a reduction in tumor development from premalignant tissue that persisted until 8, 3, and 2 months respectively. An early maximum inhibition of 100% was observed for all 3 protocols. No normal tissue radiotoxicity was detected. Reversible mucositis was observed in premalignant tissue, peaking at 1 week and resolving by the third week after each irradiation. Mucositis after the second application was not exacerbated by the first application. DNA synthesis was significantly reduced in premalignant tissue 8 months post-BNCT. A double application of BPA-BNCT and (GB-10 + BPA)-BNCT, 6 weeks apart, could be used therapeutically at no additional cost in terms of radiotoxicity in normal and dose-limiting tissues.

  12. Probe of the electron correlation in sequential double ionization of helium by two-color attosecond pulses

    NASA Astrophysics Data System (ADS)

    Peng, Liang-You; Zhang, Zheng; Jiang, Wei-Chao; Zhang, Gong-Qiu; Gong, Qihuang

    2012-12-01

    We theoretically study the sequential double ionization of He by two-color attosecond pulses. We show that, for short time delays between the two pulses, the ionization spectra cannot be explained by an independent model based on the time-dependent perturbation theory. By varying the time delay, one can probe the role of the electron correlation played in the double ionization, which is mostly obvious by examining the differential double-ionization yield. In the present scheme, we also identify a kind of “catch-up” interaction between the two ionized electrons.

  13. Electron diffraction self-imaging of molecular fragmentation in two-step double ionization of water.

    PubMed

    Sann, H; Jahnke, T; Havermeier, T; Kreidi, K; Stuck, C; Meckel, M; Schöffler, M S; Neumann, N; Wallauer, R; Voss, S; Czasch, A; Jagutzki, O; Weber, Th; Schmidt-Böcking, H; Miyabe, S; Haxton, D J; Orel, A E; Rescigno, T N; Dörner, R

    2011-04-01

    We doubly ionize H(2)O by single photon absorption at 43 eV leading to H(+) + OH(+). A direct double ionization and a sequential process in which single ionization is followed by rapid dissociation into a proton and an autoionizing OH(*) are identified. The angular distribution of this delayed autoionization electron shows a preferred emission in the direction of the emitted proton. From this diffraction feature we obtain internuclear distances of 700 to 1100 a.u. at which the autoionization of the OH(*) occurs. The experimental findings are in line with calculations of the excited potential energy surfaces and their lifetimes. PMID:21517378

  14. Generation and Analysis of Subpicosecond Double Electron Bunch at the Brookhaven Accelerator Test Facility

    SciTech Connect

    Babzien, M.; Kusche, K.; Yakimenko, V.; Zhou, F.; Kimura, Wayne D.; Cline, D.B.; Ding, X.P.; /UCLA

    2011-08-09

    Two compressed electron beam bunches from a single 60-MeV bunch have been generated in a reproducible manner during compression in the magnetic chicane - 'dog leg' arrangement at ATF. Measurements indicate they have comparable bunch lengths ({approx}100-200 fs) and are separated in energy by {approx}1.8 MeV with the higher-energy bunch preceding the lower-energy bunch by 0.5-1 ps. Some simulation results for analyzing the double-bunch formation process are also presented.

  15. Optically Detected Electron-Nuclear Double Resonance of As-Antisite Defects in GaAs

    NASA Astrophysics Data System (ADS)

    Hofmann, D. M.; Meyer, B. K.; Lohse, F.; Spaeth, J.-M.

    1984-09-01

    This Letter reports on the first optically detected electron-nuclear double-resonance (ENDOR) measurements of a paramagnetic semiconductor defect in which ligand hyperfine interactions could be resolved. In semi-insulating GaAs: Cr the ENDOR lines of the first-shell 75As neighbors of the regular tetrahedral AsAs4-antisite defect could be detected and analyzed. The ENDOR investigation reveals that at least one other AsAs4-antisite complex contributes to the same ESR spectrum.

  16. Dispersive Readout of a Few-Electron Double Quantum Dot with Fast rf Gate Sensors

    NASA Astrophysics Data System (ADS)

    Colless, J. I.; Mahoney, A. C.; Hornibrook, J. M.; Doherty, A. C.; Lu, H.; Gossard, A. C.; Reilly, D. J.

    2013-01-01

    We report the dispersive charge-state readout of a double quantum dot in the few-electron regime using the in situ gate electrodes as sensitive detectors. We benchmark this gate sensing technique against the well established quantum point contact charge detector and find comparable performance with a bandwidth of ˜10MHz and an equivalent charge sensitivity of ˜6.3×10-3e/Hz. Dispersive gate sensing alleviates the burden of separate charge detectors for quantum dot systems and promises to enable readout of qubits in scaled-up arrays.

  17. Structural and electronic properties of boron-doped double-walled silicon carbide nanotubes

    NASA Astrophysics Data System (ADS)

    Behzad, Somayeh; Moradian, Rostam; Chegel, Raad

    2010-12-01

    The effects of boron doping on the structural and electronic properties of (6,0)@(14,0) double-walled silicon carbide nanotube (DWSiCNT) are investigated by using spin-polarized density functional theory. It is found that boron atom could be more easily doped in the inner tube. Our calculations indicate that a Si site is favorable for B under C-rich condition and a C site is favorable under Si-rich condition. Additionally, B-substitution at either single carbon or silicon atom site in DWSiCNT could induce spontaneous magnetization.

  18. Observation of double electron-positron pair production by {gamma} rays reexamined

    SciTech Connect

    Maidana, N. L.; Oliveira, J. R. B.; Rizzutto, M. A.; Added, N.; Vanin, V. R.; Brualla, L.; Fernandez-Varea, J. M.

    2009-04-15

    An experiment was conducted to observe triple- and quadruple-escape peaks, at a photon energy equal to 6.128 MeV, in the spectra recorded with a high-purity Ge detector working in coincidence with six bismuth germanate detectors. The peak intensities may be explained having recourse to only the bremsstrahlung cascade process of consecutive electron-positron pair creation; i.e., the contribution of simultaneous double pair formation (and other cascade effects) is much smaller. The experimental peak areas are in reasonably good agreement with those predicted by Monte Carlo simulations done with the general-purpose radiation-transport code PENELOPE.

  19. Detection of trace levels of triclopyr using capillary gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry.

    PubMed

    Begley, P; Foulger, B E

    1988-04-01

    Triclopyr, after esterification, is shown to be a suitable candidate for detection by gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry forming a characteristic carboxylate anion which offers a high detection sensitivity. A detection limit of 70 fg reaching the ionizer is indicated. Low backgrounds and an absence of chemical interferences are shown for vegetation extracts, using a simple method of extraction and derivatisation. A similar behaviour is demonstrated for 2,4-D and 2,4,5-T. PMID:3379116

  20. Small amplitude electron-acoustic double layers and solitons in fully relativistic plasmas of two-temperature electrons

    SciTech Connect

    Lee, Nam C.

    2009-04-15

    A Korteweg-de Vries (KdV) equation for fully relativistic one dimensional plasmas of arbitrarily large streaming speed and temperature is derived by using the reductive perturbation method. For plasmas with more than two species of particles, the coefficient representing quadratic nonlinearity in KdV can vanish at critical values of certain parameters. To describe the nonlinear evolution at this critical parameter, a modified KdV (mKdV) equation that contains a cubic nonlinear term is obtained. Furthermore, a mixed mKdV equation pertaining to parameters in the vicinity of the critical values is also derived, in which the quadratic and cubic nonlinearities are both present. As an illustration of the results, the mixed mKdV equation is applied to a plasma comprised of cold ions and electrons having cold (T=0) and finite temperature components. For warm temperature T<electron-acoustic nonlinear waves in the shape of double layer (kink) and solitary waves can exist, which have phase speed {radical}(3T/(4+{alpha})m{sub e}) in the rest frame of plasma, where {alpha} is the polytropic index of the equation of state of the warm electrons. The thickness of the transitional layer of the kink structure is of the order of Debye length {lambda}{sub D}. For extremely high temperature T>>m{sub e}c{sup 2}, it is also found that double layer and soliton-type solutions can exist with phase speed {radical}({alpha}-1)c, which is equal to the well known relativistic sound speed c/{radical}(3) for {alpha}=4/3. The thickness of the transition layer scales as {delta}{approx}T{sup -1/4}, which is different from the T<

  1. Ion acoustic solitary waves and double layers in a plasma with two temperature electrons featuring Tsallis distribution

    SciTech Connect

    Shalini, Saini, N. S.

    2014-10-15

    The propagation properties of large amplitude ion acoustic solitary waves (IASWs) are studied in a plasma containing cold fluid ions and multi-temperature electrons (cool and hot electrons) with nonextensive distribution. Employing Sagdeev pseudopotential method, an energy balance equation has been derived and from the expression for Sagdeev potential function, ion acoustic solitary waves and double layers are investigated numerically. The Mach number (lower and upper limits) for the existence of solitary structures is determined. Positive as well as negative polarity solitary structures are observed. Further, conditions for the existence of ion acoustic double layers (IADLs) are also determined numerically in the form of the critical values of q{sub c}, f and the Mach number (M). It is observed that the nonextensivity of electrons (via q{sub c,h}), concentration of electrons (via f) and temperature ratio of cold to hot electrons (via β) significantly influence the characteristics of ion acoustic solitary waves as well as double layers.

  2. Measurement of the {beta}{sup +} and Orbital Electron-Capture Decay Rates in Fully Ionized, Hydrogenlike, and Heliumlike {sup 140}Pr Ions

    SciTech Connect

    Litvinov, Yu. A.; Geissel, H.; Winckler, N.; Knoebel, R.; Litvinov, S. A.; Scheidenberger, C.; Bosch, F.; Beckert, K.; Brandau, C.; Dimopoulou, C.; Hess, S.; Kozhuharov, C.; Mazzocco, M.; Nociforo, C.; Nolden, F.; Prochazka, A.; Reuschl, R.; Steck, M.; Stoehlker, T.; Trassinelli, M.

    2007-12-31

    We report on the first measurement of the {beta}{sup +} and orbital electron-capture decay rates of {sup 140}Pr nuclei with the simplest electron configurations: bare nuclei, hydrogenlike, and heliumlike ions. The measured electron-capture decay constant of hydrogenlike {sup 140}Pr{sup 58+} ions is about 50% larger than that of heliumlike {sup 140}Pr{sup 57+} ions. Moreover, {sup 140}Pr ions with one bound electron decay faster than neutral {sup 140}Pr{sup 0+} atoms with 59 electrons. To explain this peculiar observation one has to take into account the conservation of the total angular momentum, since only particular spin orientations of the nucleus and of the captured electron can contribute to the allowed decay.

  3. Coloidal gold, ferritin and peroxidase as markers for electron microscopic double labeling lectin techniques.

    PubMed

    Roth, J; Binder, M

    1978-03-01

    Three markers, colloidal gold, ferritin and peroxidase, were checked for usefulness in double labeling of lectin-binding sites. The amount of various lectins for the stabilization of good sols of a different particle size was evaluated. Several lectin-gold complexes were prepared for electron microscopic labeling purposes, and the optimal amount of various lectins needed for stabilization of gold solutions of a different particle size was determined. The following combinations were investigated for their usefulness in labeling two different lectin-binding sites: lectin-gold and lectin-gold (different particle size), lectin-gold and lectin-ferritin, as well as lectin-ferritin and lectin-peroxidase. Of these combinations the latter did not give satisfactory results for double labeling. In all single and double labeling techniques with the above mentioned markers the quantitative evaluation of the number of lectin-binding sites is not feasible, but these techniques will be of considerable value for the investigation of the dynamics of different lectin-binding sites on the cell surface. PMID:632554

  4. Interface for electronic data capture systems for clinical trials by optimal utilization of available hospital resources.

    PubMed

    Kaushik, Sashank; Khan, Anzalee; Kaushik, Saurabh; Lindenmayer, Jean-Pierre

    2008-01-01

    We describe Clinical Trials System (CTS), an innovative EDC system utilizing data from existing hospital-based electronic databases that supports information gathering and storing for various clinical trials. The complexities of designing electronic clinical trials systems and their ideal features are outlined. CTS optimally utilizes existing electronic databases in a well-organized and easy-to-reference format. CTS is currently incorporated within a large psychiatric center, allowing easy sharing of information and data among multidisciplinary clinical and research teams. PMID:18999083

  5. Performance optimization of total momentum filtering double-resonance energy selective electron heat pump

    NASA Astrophysics Data System (ADS)

    Ding, Ze-Min; Chen, Lin-Gen; Ge, Yan-Lin; Sun, Feng-Rui

    2016-04-01

    A theoretical model for energy selective electron (ESE) heat pumps operating with two-dimensional electron reservoirs is established in this study. In this model, a double-resonance energy filter operating with a total momentum filtering mechanism is considered for the transmission of electrons. The optimal thermodynamic performance of the ESE heat pump devices is also investigated. Numerical calculations show that the heating load of the device with two resonances is larger, whereas the coefficient of performance (COP) is lower than the ESE heat pump when considering a single-resonance filter. The performance characteristics of the ESE heat pumps in the total momentum filtering condition are generally superior to those with a conventional filtering mechanism. In particular, the performance characteristics of the ESE heat pumps considering a conventional filtering mechanism are vastly different from those of a device with total momentum filtering, which is induced by extra electron momentum in addition to the horizontal direction. Parameters such as resonance width and energy spacing are found to be associated with the performance of the electron system.

  6. Evolution of electronic states in n-type copper oxide superconductor via electric double layer gating

    PubMed Central

    Jin, Kui; Hu, Wei; Zhu, Beiyi; Kim, Dohun; Yuan, Jie; Sun, Yujie; Xiang, Tao; Fuhrer, Michael S.; Takeuchi, Ichiro; Greene, Richard. L.

    2016-01-01

    The occurrence of electrons and holes in n-type copper oxides has been achieved by chemical doping, pressure, and/or deoxygenation. However, the observed electronic properties are blurred by the concomitant effects such as change of lattice structure, disorder, etc. Here, we report on successful tuning the electronic band structure of n-type Pr2−xCexCuO4 (x = 0.15) ultrathin films, via the electric double layer transistor technique. Abnormal transport properties, such as multiple sign reversals of Hall resistivity in normal and mixed states, have been revealed within an electrostatic field in range of −2 V to + 2 V, as well as varying the temperature and magnetic field. In the mixed state, the intrinsic anomalous Hall conductivity invokes the contribution of both electron and hole-bands as well as the energy dependent density of states near the Fermi level. The two-band model can also describe the normal state transport properties well, whereas the carrier concentrations of electrons and holes are always enhanced or depressed simultaneously in electric fields. This is in contrast to the scenario of Fermi surface reconstruction by antiferromagnetism, where an anti-correlation is commonly expected. PMID:27221198

  7. Evolution of electronic states in n-type copper oxide superconductor via electric double layer gating

    NASA Astrophysics Data System (ADS)

    Jin, Kui; Hu, Wei; Zhu, Beiyi; Kim, Dohun; Yuan, Jie; Sun, Yujie; Xiang, Tao; Fuhrer, Michael S.; Takeuchi, Ichiro; Greene, Richard. L.

    2016-05-01

    The occurrence of electrons and holes in n-type copper oxides has been achieved by chemical doping, pressure, and/or deoxygenation. However, the observed electronic properties are blurred by the concomitant effects such as change of lattice structure, disorder, etc. Here, we report on successful tuning the electronic band structure of n-type Pr2‑xCexCuO4 (x = 0.15) ultrathin films, via the electric double layer transistor technique. Abnormal transport properties, such as multiple sign reversals of Hall resistivity in normal and mixed states, have been revealed within an electrostatic field in range of ‑2 V to + 2 V, as well as varying the temperature and magnetic field. In the mixed state, the intrinsic anomalous Hall conductivity invokes the contribution of both electron and hole-bands as well as the energy dependent density of states near the Fermi level. The two-band model can also describe the normal state transport properties well, whereas the carrier concentrations of electrons and holes are always enhanced or depressed simultaneously in electric fields. This is in contrast to the scenario of Fermi surface reconstruction by antiferromagnetism, where an anti-correlation is commonly expected.

  8. Interaction-driven capacitance in graphene electron-hole double layer in strong magnetic fields

    NASA Astrophysics Data System (ADS)

    Roostaei, Bahman

    2015-12-01

    Fabrication of devices made by isolated graphene layers has opened up possibility of examining highly correlated states of electron systems in parts of their phase diagram that is impossible to access in their counterpart devices such as semiconductor heterostructures. An example of such states are graphene double monolayer electron-hole systems under strong magnetic fields where the separation between layers can be adjusted to be as small as one magnetic length with interlayer tunneling still suppressed. In those separations, it is known that correlations between electrons and holes are of crucial importance and must be included in determination of observable quantities. Here we report the results of our full numerical Hartree-Fock study of coherent and crystalline ground states of the interacting balanced electron-hole graphene systems in small and intermediate separations with each layer occupying up to four lowest lying Landau levels. We show that in the Hartree-Fock approximation the electrons and holes pair to form a homogeneous Bose-condensed (excitonic) state, while crystalline states of such exciton systems remain incoherent at intermediate layer separations. Our results of calculation of capacitance of such states as a function of interlayer separation and filling factor provides quantitative and qualitative signatures that can be examined in real experiments. We show that the capacitance of some crystallized states as well as uniform coherent states are significantly enhanced compared to geometrical values solely due to Coulomb interactions and quantum corrections.

  9. Evolution of electronic states in n-type copper oxide superconductor via electric double layer gating.

    PubMed

    Jin, Kui; Hu, Wei; Zhu, Beiyi; Kim, Dohun; Yuan, Jie; Sun, Yujie; Xiang, Tao; Fuhrer, Michael S; Takeuchi, Ichiro; Greene, Richard L

    2016-01-01

    The occurrence of electrons and holes in n-type copper oxides has been achieved by chemical doping, pressure, and/or deoxygenation. However, the observed electronic properties are blurred by the concomitant effects such as change of lattice structure, disorder, etc. Here, we report on successful tuning the electronic band structure of n-type Pr2-xCexCuO4 (x = 0.15) ultrathin films, via the electric double layer transistor technique. Abnormal transport properties, such as multiple sign reversals of Hall resistivity in normal and mixed states, have been revealed within an electrostatic field in range of -2 V to + 2 V, as well as varying the temperature and magnetic field. In the mixed state, the intrinsic anomalous Hall conductivity invokes the contribution of both electron and hole-bands as well as the energy dependent density of states near the Fermi level. The two-band model can also describe the normal state transport properties well, whereas the carrier concentrations of electrons and holes are always enhanced or depressed simultaneously in electric fields. This is in contrast to the scenario of Fermi surface reconstruction by antiferromagnetism, where an anti-correlation is commonly expected. PMID:27221198

  10. Fuzzy-logic-based approach to study the electrons mobility in nanoscale Double Gate MOSFETs

    NASA Astrophysics Data System (ADS)

    Bendib, T.; Djeffal, F.; Arar, D.; Dibi, Z.; Ferdi, A.

    2012-12-01

    The Double Gate silicon (DG) MOSFET with extremely short-channel length has the appropriate features to constitute the devices for nanoscale circuit design. To develop a physical model for extremely scaled DG MOSFETs, the electron mobility distribution throughout the channel must be accurately determined under the application of drain and gate voltages. However, the modeling of the transport behavior for the nanoscale structures requires the use of overkill methods and models in terms of complexity and computation time (self-consistent, quantum computations,..). Therefore, new methods and techniques are required to overcome these constraints. In this work, a new approach based on the fuzzy logic computation is proposed to model the electron mobility behavior for nanoscale DG MOSFETs. The proposed approach can be implemented into devices simulator to study the nanoscale CMOS-based circuits.

  11. Double-twist cylinders in liquid crystalline cholesteric blue phases observed by transmission electron microscopy.

    PubMed

    Tanaka, Shu; Yoshida, Hiroyuki; Kawata, Yuto; Kuwahara, Ryusuke; Nishi, Ryuji; Ozaki, Masanori

    2015-01-01

    Cholesteric blue phases are liquid crystalline phases in which the constituent rod-like molecules spontaneously form three-dimensional, helical structures. Despite theoretical predictions that they are composed of cylindrical substructures within which the liquid crystal molecules are doubly twisted, real space observation of the arrangement of such structures had not been performed. Through transmission electron microscopy of photopolymerized blue phases with controlled lattice plane orientations, we report real space observation and comparison of the lattice structures of blue phases I and II. The two systems show distinctly different contrasts, reflecting the theoretically predicted, body centred and simple cubic arrangement of the double-twist cylinders. Transmission electron microscopy also reveals different tendencies of the two blue phases to align on unidirectionally rubbed surfaces. We thus show that TEM observation of alignment-controlled, photopolymerized liquid crystals can be a powerful tool to investigate complex liquid crystalline order. PMID:26530779

  12. Hysteresis in the Quantum Hall Regimes in Electron Double-Quantum Structures

    NASA Astrophysics Data System (ADS)

    Pan, W.; Reno, J. L.; Simmons, J. A.

    We present in this paper the experimental results of transport hysteresis in an extremely imbalanced electron double-quantum-well (DQW) structure. The ratio of the top layer density (ntop) to bottom layer density (nbot) is continuously tuned by applying voltage to a front gate. Under a condition when the top layer is nearly depleted (ntop~3×1010 cm-2) while the bottom layer remains at nbot=1.9×1011 cm-2, the hysteresis is absent in the B sweeps as long as the total Landau level filling ν<1 and the 2D electron systems are in the fractional quantum Hall effect regime. Surprisingly, a large hysteresis is observed during the gate sweeps at the same values of B and ntop. We attribute this unexpected hysteresis to the formation of an insulating state, probably a weakly pinned Wigner solid state, in the top layer.

  13. Hysteresis in the Quantum Hall Regimes in Electron Double-Quantum Structures

    NASA Astrophysics Data System (ADS)

    Pan, W.; Reno, J. L.; Simmons, J. A.

    2005-04-01

    We present in this paper the experimental results of transport hysteresis in an extremely imbalanced electron double-quantum-well (DQW) structure. The ratio of the top layer density (ntop) to bottom layer density (nbot) is continuously tuned by applying voltage to a front gate. Under a condition when the top layer is nearly depleted (ntop ~ 3×1010 cm-2) while the bottom layer remains at nbot = 1.9 × 1011 cm-2, the hysteresis is absent in the B sweeps as long as the total Landau level filling ν < 1 and the 2D electron systems are in the fractional quantum Hall effect regime. Surprisingly, a large hysteresis is observed during the gate sweeps at the same values of B and ntop. We attribute this unexpected hysteresis to the formation of an insulating state, probably a weakly pinned Wigner solid state, in the top layer.

  14. Double-twist cylinders in liquid crystalline cholesteric blue phases observed by transmission electron microscopy

    PubMed Central

    Tanaka, Shu; Yoshida, Hiroyuki; Kawata, Yuto; Kuwahara, Ryusuke; Nishi, Ryuji; Ozaki, Masanori

    2015-01-01

    Cholesteric blue phases are liquid crystalline phases in which the constituent rod-like molecules spontaneously form three-dimensional, helical structures. Despite theoretical predictions that they are composed of cylindrical substructures within which the liquid crystal molecules are doubly twisted, real space observation of the arrangement of such structures had not been performed. Through transmission electron microscopy of photopolymerized blue phases with controlled lattice plane orientations, we report real space observation and comparison of the lattice structures of blue phases I and II. The two systems show distinctly different contrasts, reflecting the theoretically predicted, body centred and simple cubic arrangement of the double-twist cylinders. Transmission electron microscopy also reveals different tendencies of the two blue phases to align on unidirectionally rubbed surfaces. We thus show that TEM observation of alignment-controlled, photopolymerized liquid crystals can be a powerful tool to investigate complex liquid crystalline order. PMID:26530779

  15. Double-twist cylinders in liquid crystalline cholesteric blue phases observed by transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Tanaka, Shu; Yoshida, Hiroyuki; Kawata, Yuto; Kuwahara, Ryusuke; Nishi, Ryuji; Ozaki, Masanori

    2015-11-01

    Cholesteric blue phases are liquid crystalline phases in which the constituent rod-like molecules spontaneously form three-dimensional, helical structures. Despite theoretical predictions that they are composed of cylindrical substructures within which the liquid crystal molecules are doubly twisted, real space observation of the arrangement of such structures had not been performed. Through transmission electron microscopy of photopolymerized blue phases with controlled lattice plane orientations, we report real space observation and comparison of the lattice structures of blue phases I and II. The two systems show distinctly different contrasts, reflecting the theoretically predicted, body centred and simple cubic arrangement of the double-twist cylinders. Transmission electron microscopy also reveals different tendencies of the two blue phases to align on unidirectionally rubbed surfaces. We thus show that TEM observation of alignment-controlled, photopolymerized liquid crystals can be a powerful tool to investigate complex liquid crystalline order.

  16. Electromagnetic properties of a double-layer graphene system with electron-hole pairing

    NASA Astrophysics Data System (ADS)

    Germash, K. V.; Fil, D. V.

    2016-05-01

    We study electromagnetic properties of a double-layer graphene system in which electrons from one layer are coupled with holes from the other layer. The gauge invariant linear response functions are obtained. The frequency dependences of the transmission, reflection, and absorption coefficients are computed. We predict a peak in the reflection and absorption at the frequency equal to the gap in the quasiparticle spectrum. It is shown that the electron-hole pairing results in an essential modification of the spectrum of surface TM plasmons. We find that the optical TM mode splits into a low frequency undamped branch and a high frequency damped branch. At zero temperature the lower branch disappears. It is established that the pairing does not influence the acoustic TM mode. It is also shown that the pairing opens the frequency window in the subgap range for the surface TE wave.

  17. Using magnetic stripes to stabilize superfluidity in electron-hole double monolayer graphene

    NASA Astrophysics Data System (ADS)

    Dell'Anna, Luca; Perali, Andrea; Covaci, Lucian; Neilson, David

    2015-12-01

    Experiments have confirmed that double monolayer graphene does not generate finite-temperature electron-hole superfluidity, because of very strong screening of the pairing attraction. The linear dispersing energy bands in monolayer graphene block any attempt to reduce the strength of the screening. We propose a hybrid device with two sheets of monolayer graphene in a modulated periodic perpendicular magnetic field. The field preserves the isotropic Dirac cones of the original monolayers but reduces the slope of the cones, making the monolayer Fermi velocity vF smaller. We demonstrate that with current experimental techniques, the reduction in vF can weaken the screening sufficiently to allow electron-hole superfluidity at measurable temperatures.

  18. Ion-acoustic solitons, double layers and rogue waves in plasma having superthermal electrons

    NASA Astrophysics Data System (ADS)

    Singh Saini, Nareshpal

    2016-07-01

    Most of the space and astrophysical plasmas contain different type of charged particles with non-Maxwellian velocity distributions (e.g., nonthermal, superthermal, Tsallis ). These distributions are commonly found in the auroral region of the Earth's magnetosphere, planetary magnetosphere, solar and stellar coronas, solar wind, etc. The observations from various satellite missions have confirmed the presence of superthermal particles in space and astrophysical environments. Over the last many years, there have been a much interest in studying the different kind of properties of the electrostatic nonlinear excitations (solitons, double layers, rogue waves etc.) in a multi-component plasmas in the presence of superthermal particles. It has been analyzed that superthermal distributions are more appropriate than Maxwellian distribution for the modeling of space data. It is interesting to study the dynamics of various kinds of solitary waves, Double layers, Shocks etc. in varieties of plasma systems containing different kind of species obeying Lorentzian (kappa-type)/Tsallis distribution. In this talk, I have focused on the study of large amplitude IA solitary structures (bipolar solitary structures, double layers etc.), modulational instability and rogue waves in multicomponent plasmas. The Sagdeev potential method has been employed to setup an energy balance equation, from which we have studied the characteristics of large amplitude solitary waves under the influence of superthermality of charged particles and other plasma parameters. The critical Mach number has been determined, above which solitary structures are observed and its variation with superthermality of electrons and other parameters has also been discussed. Double layers have also been discussed. Multiple scale reductive perturbation method has been employed to derive NLS equation. From the different kind of solutions of this equation, amplitude modulation of envelope solitons and rogue waves have been

  19. Surface hopping with a manifold of electronic states. I. Incorporating surface-leaking to capture lifetimes

    SciTech Connect

    Ouyang, Wenjun; Dou, Wenjie; Subotnik, Joseph E.

    2015-02-28

    We investigate the incorporation of the surface-leaking (SL) algorithm into Tully’s fewest-switches surface hopping (FSSH) algorithm to simulate some electronic relaxation induced by an electronic bath in conjunction with some electronic transitions between discrete states. The resulting SL-FSSH algorithm is benchmarked against exact quantum scattering calculations for three one-dimensional model problems. The results show excellent agreement between SL-FSSH and exact quantum dynamics in the wide band limit, suggesting the potential for a SL-FSSH algorithm. Discrepancies and failures are investigated in detail to understand the factors that will limit the reliability of SL-FSSH, especially the wide band approximation. Considering the easiness of implementation and the low computational cost, we expect this method to be useful in studying processes involving both a continuum of electronic states (where electronic dynamics are probabilistic) and processes involving only a few electronic states (where non-adiabatic processes cannot ignore short-time coherence)

  20. Bond cleavage reactions in the tripeptide trialanine upon free electron capture

    NASA Astrophysics Data System (ADS)

    Puschnigg, Benjamin; Huber, Stefan E.; Scheier, Paul; Probst, Michael; Denifl, Stephan

    2014-05-01

    In the present study we performed dissociative electron attachment (DEA) measurements with the tripeptide trialanine, C9H17N3O4, utilizing a crossed electron-molecular beam experiment with high electron energy resolution (~100 meV). Anion efficiency yields as a function of the incident electron energy are obtained for the most abundant anions up to electron energies of ~4 eV. Quantum chemical calculations are performed to determine the thermochemical thresholds for the anions observed in the measurements. There is no evidence of a molecular anion with lifetime of mass spectrometric timescales. The dehydrogenated closed shell anion (M-H)- is one of the fragment anions observed for which the calculations show that H-loss is energetically possible from carboxyl, as well as amide groups. In contrast to the dipeptide dialanine and monomer alanine the cleavage of the N-Cα bond in the peptide chain is already possible by attachment of electrons at ~0 eV. Contribution to the Topical Issue "Nano-scale Insights into Ion-beam Cancer Therapy", edited by Andrey V. Solov'yov, Nigel Mason, Paulo Limão-Vieira and Malgorzata Smialek-Telega.

  1. Electron capture decay of 58-min U-229(92) and levels in Pa-229(91)

    SciTech Connect

    Ahmad, I.; Chasman, R. R.; Greene, J. P.; Kondev, F. G.; Zhu, S.

    2015-08-17

    Electron capture decay of U-229 is investigated by measuring the gamma-ray and conversion electron spectra of mass-separated and unseparated U-229 sources with high-resolution germanium and silicon detectors, respectively. Gamma-gamma coincidence measurements are also performed using germanium detectors. These studies provide level energies and level ordering in Pa-229. Single-particle assignments are given to these levels which are in agreement with the systematics in this region and also with theory. In a previous study, we report the observation of a 5/2(+/-) parity doublet in the Pa-229 ground state, which is a signature of octupole deformation. The present analysis of the data still shows a splitting of 60 +/- 50 eV, but with this large uncertainty the existence of the doublet is not certain.

  2. Phospholipid bilayer relaxation dynamics as revealed by the pulsed electron-electron double resonance of spin labels

    NASA Astrophysics Data System (ADS)

    Syryamina, V. N.; Dzuba, S. A.

    2012-10-01

    Electron paramagnetic resonance (EPR) spectroscopy in the form of pulsed electron-electron double resonance (ELDOR) was applied to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) phospholipid bilayers containing lipids that were spin-labeled at different carbon positions along the lipid acyl chain. Pulsed ELDOR detects motionally induced spin flips of nitrogen nuclei in the nitroxide spin labels, which manifests itself as magnetization transfer (MT) in the nitroxide EPR spectrum. The MT effect was observed over a wide temperature range (100-225 K) on a microsecond time scale. In line with a previous study on molecular glasses [N. P. Isaev and S. A. Dzuba, J. Chem. Phys. 135, 094508 (2011), 10.1063/1.3633241], the motions that induce MT effect were suggested to have the same nature as those in dielectric secondary (β) Johari-Goldstein fast relaxation. The results were compared with literature dielectric relaxation data for POPC bilayers, revealing some common features. Molecular motions resulting in MT are faster for deeper spin labels in the membrane interior. The addition of cholesterol to the bilayer suppresses the lipid motions near the steroid nucleus and accelerates the lipid motions beyond the steroid nucleus, in the bilayer interior. This finding was attributed to the lipid acyl chains being more ordered near the steroid nucleus and less ordered in the bilayer interior. The motions are absent in dry lipids, indicating that the motions are determined by intermolecular interactions in the bilayer.

  3. Measurement of electron capture from e+-e- pair production by 0.956 GeV/u U92+ on Au, Ag, Cu, and Mylar targets

    NASA Astrophysics Data System (ADS)

    Belkacem, A.; Gould, Harvey; Feinberg, B.; Bossingham, R.; Meyerhof, W. E.

    1993-12-01

    We describe the first experimental observation of electron capture from electron-positron pair production in relativistic heavy ion collisions. We have used a novel new spectrometer to make the measurement of the cross section for a 0.956 GeV/u U92+ beam produced at the BEVALAC facility at LBL on Au, Ag, Cu, and Mylar targets. We also measured the energy and angular distribution of the positrons for the Au target. The total cross section for a Au target is measured to be 2.19 (0.25) barns for capture from pair production and 3.30 (0.65) barns for pair production without capture.

  4. Current suppression in a double-island single-electron transistor for detection of degenerate charge configurations of a floating double-dot

    NASA Astrophysics Data System (ADS)

    Brenner, R.; Greentree, Andrew D.; Hamilton, A. R.

    2003-12-01

    We have investigated a double-island single-electron transistor (DISET) coupled to a floating metal double-dot (DD). Low-temperature transport measurements were used to map out the charge configurations of both the DISET and the DD. A suppression of the current through the DISET was observed whenever the charge configurations of the DISET and the DD were energetically codegenerate. This effect was used to distinguish between degenerate and nondegenerate charge configurations of the DD. We also show that this detection scheme reduces the susceptibility of the DISET to interference from random charge noise.

  5. Influence of electron capture after-effects on the stability of 111In( 111Cd)-complexes with organic ligands

    NASA Astrophysics Data System (ADS)

    Shpinkova, L. G.; Carbonari, A. W.; Nikitin, S. M.; Mestnik-Filho, J.

    2002-06-01

    The TDPAC technique was applied to verify a hypothesis about the influence of electron capture after-effects on the integrity of radiometal complexes with organic ligands in aqueous solutions. The neutral aqueous solutions of DTPA-complexes with two parent isotopes, 111In(EC) 111Cd and 111mCd, were used for direct comparison of dynamic interaction parameters. Data for the parent 111In-DTPA complexes revealed three fractions with essentially different relaxation constants, including an "unperturbed" fraction, which, according to the hypothesis, is due to small fragments of the initial complexes disintegrated as a result of Auger-process and the following Coulomb fragmentation. Only one fraction with a relaxation constant of 3(1)×10 6 s-1 was observed for the 111mCd-DTPA solution confirming the proposal about the influence of electron capture after-effects. Measurements with the frozen solutions allowed determining the electric field gradient (EFG) at Cd-sites in complexes with DTPA, V zz=6.7(2)×10 21 V/m2 with an asymmetry parameter η=0.75(5).

  6. Convolution/deconvolution of generalized Gaussian kernels with applications to proton/photon physics and electron capture of charged particles

    NASA Astrophysics Data System (ADS)

    Ulmer, W.

    2013-02-01

    Scatter processes of photons lead to blurring of images produced by CT (computed tomography) or CBCT (cone beam computed tomography). Multiple scatter is described by, at least, one Gaussian kernel. In various tasks, this approximation is crude; we need two/three Gaussian kernels to account for long-range tails (Landau tails), which appear in Molière scatter of protons, energy straggling and electron capture of charged particles passing through matter and Compton scatter. The ideal image (source function) is subjected to Gaussian convolution to yield a blurred image. The inverse problem is to obtain the source image from a detected image. Deconvolution methods of linear combinations of two/three Gaussian kernels with different parameters s0, s1, s2 can be derived via an inhomogeneous Fredholm integral equation of second kind (IFIE2) and Liouville - Neumann series (LNS) to provide the source function ρ. Scatter functions s0, s1, s2 are best determined by Monte-Carlo. An advantage of LNS is given, if the scatter functions s0, s1, s2 depend on coordinates. The convergence criterion can always be satisfied with regard to the above mentioned cases. A generalization is given by an analysis of the Dirac equation and Fermi-Dirac statistics leading to Landau tails applied to Bethe-Bloch equation (BBE) of charged particles and electron capture.

  7. Identification of Neisseria by electron capture gas-liquid chromatography of metabolites in a chemically defined growth medium.

    PubMed Central

    Morse, C D; Brooks, J B; Kellogg, D S

    1977-01-01

    A dual-purpose study was carried out in an attempt to develop a rapid, sensitive method to identify Neisseria species by gas chromatography and to learn more about the metabolism of these organisms. Sixty-nine isolates of Neisseria were grown in a chemically defined fluid medium; the spent medium was extracted sequentially at pH 2 with diethyl ether and at pH 10 with chloroform. The pH 10 extracts were derivatized with heptafluorobutyric anhydride and analyzed by electron capture gas-liquid chromatography. The resulting spent culture medium electron capture gas-liquid chromatography profiles showed several qualitative and significant quantitative differences among the Neisseria species potentially useful in separating and identifying these organisms. Putrescine and cadaverine which were present in the spent culture medium of some Neisseria, including N. gonorrhoeae, were tentatively identified. Substituting carbohydrates for the chemically defined medium containing glucose in the base medium produced altered profiles with increased quantitative and qualitative differences. PMID:21889

  8. Analysis of the substate distribution of H(n=3) atoms from electron capture by protons on Ar

    SciTech Connect

    Renwick, S.P.; Martell, E.C.; Weaver, W.D.; Risley, J.S.

    1993-05-01

    We present a measurement of diagonal and real off-diagonal germs of the density matrix describing H(n=3) atoms produced by electron capture of 20 - 100 keV protons colliding with Ar. These elements of the excited atoms` density matrix are used to determine important parameters of the collisionally-produced H atom, including the atom`s electric dipole moment and cross sections for electron capture to angular momentum substates of n=3. The matrix is determined by analysis of the polarization of Balmer-{alpha} light emitted by the radiative decay of the atoms in an external electric field. A new polarimeter, employing a photoelastic modulator, has allowed us to subtract undesired background from excited Ar atoms. The dipole moment and the probablity density of the excited H atoms produced from the Ar target show similar qualitative behavior to those from a He target at higher beam energies, while their behavior is markedly different below 35 keV. Data will be presented along with a comparison of the PEM to other polarimeters.

  9. On the Significance of the Contribution of Multiple-Electron Capture Processes to Cometary X-Ray Emission

    SciTech Connect

    Ali, R; Neill, P A; Beiersdorfer, P; Harris, C L; Rakovi?, M J; Wang, J G; Schultz, D R; Stancil, P C

    2005-05-12

    We report laboratory studies of the role played by multiple-electron capture (MEC) in solar wind induced cometary X-ray emission. Collisions of Ne{sup 10+} with He, Ne, Ar, CO, and CO{sub 2} have been investigated by means of the traditional singles X-ray spectroscopy in addition to the triple-coincidence measurements of X-rays, scattered projectile, and target recoil ions for the atomic targets. The coincidence measurements enable the reduction of the singles X-ray spectra into partial spectra originating in single-electron capture (SEC) and MEC collisions. The measurements provide unequivocal evidence for a significant role played by MEC, and strongly suggest that models based solely on SEC are bound to yield erroneous conclusions on the solar wind composition and velocities and on cometary atmospheres. The experimental relative importance of MEC collisions is compared with molecular classical-over-the-barrier model (MCBM), classical trajectory Monte Carlo (CTMC), and multi-channel Landau-Zener (MCLZ), calculations which can qualitatively reproduce the experimental trends.

  10. Channeling, volume reflection, and volume capture study of electrons in a bent silicon crystal

    NASA Astrophysics Data System (ADS)

    Wistisen, T. N.; Uggerhøj, U. I.; Wienands, U.; Markiewicz, T. W.; Noble, R. J.; Benson, B. C.; Smith, T.; Bagli, E.; Bandiera, L.; Germogli, G.; Guidi, V.; Mazzolari, A.; Holtzapple, R.; Tucker, S.

    2016-07-01

    We present the experimental data and analysis of experiments conducted at SLAC National Accelerator Laboratory investigating the processes of channeling, volume-reflection and volume-capture along the (111) plane in a strongly bent quasimosaic silicon crystal. These phenomena were investigated at 5 energies: 3.35, 4.2, 6.3, 10.5, and 14.0 GeV with a crystal with bending radius of 0.15 m, corresponding to curvatures of 0.053, 0.066, 0.099, 0.16, and 0.22 times the critical curvature, respectively. Based on the parameters of fitting functions we have extracted important parameters describing the channeling process such as the dechanneling length, the angle of volume reflection, the surface transmission, and the widths of the distribution of channeled particles parallel and orthogonal to the plane.

  11. Nonlinear propagation of small-amplitude modified electron acoustic solitary waves and double layer in semirelativistic plasmas

    SciTech Connect

    Sah, O.P.; Goswami, K.S. )

    1994-10-01

    Considering an unmagnetized plasma consisting of relativistic drifting electrons and nondrifting thermal ions and by using reductive perturbation method, a usual Korteweg--de Vries (KdV) equation and a generalized form of KdV equation are derived. It is found that while the former governs the dynamics of a small-amplitude rarefactive modified electron acoustic (MEA) soliton, the latter governs the dynamics of a weak compressive modified electron acoustic double layer. The influences of relativistic effect on the propagation of such a soliton and double layer are examined. The relevance of this investigation to space plasma is pointed out.

  12. Final report on LDRD Project: The double electron layer tunneling transistor (DELTT)

    SciTech Connect

    Simmons, J.A.; Moon, J.S.; Blount, M.A.

    1998-06-01

    This report describes the research accomplishments achieved under the LDRD Project ``Double Electron Layer Tunneling Transistor.`` The main goal of this project was to investigate whether the recently discovered phenomenon of 2D-2D tunneling in GaAs/AlGaAs double quantum wells (DQWs), investigated in a previous LDRD, could be harnessed and implemented as the operating principle for a new type of tunneling device the authors proposed, the double electron layer tunneling transistor (DELTT). In parallel with this main thrust of the project, they also continued a modest basic research effort on DQW physics issues, with significant theoretical support. The project was a considerable success, with the main goal of demonstrating a working prototype of the DELTT having been achieved. Additional DELTT advances included demonstrating good electrical characteristics at 77 K, demonstrating both NMOS and CMOS-like bi-stable memories at 77 K using the DELTT, demonstrating digital logic gates at 77 K, and demonstrating voltage-controlled oscillators at 77 K. In order to successfully fabricate the DELTT, the authors had to develop a novel flip-chip processing scheme, the epoxy-bond-and-stop-etch (EBASE) technique. This technique was latter improved so as to be amenable to electron-beam lithography, allowing the fabrication of DELTTs with sub-micron features, which are expected to be extremely high speed. In the basic physics area they also made several advances, including a measurement of the effective mass of electrons in the hour-glass orbit of a DQW subject to in-plane magnetic fields, and both measurements and theoretical calculations of the full Landau level spectra of DQWs in both perpendicular and in-plane magnetic fields. This last result included the unambiguous demonstration of magnetic breakdown of the Fermi surface. Finally, they also investigated the concept of a far-infrared photodetector based on photon assisted tunneling in a DQW. Absorption calculations showed a

  13. Dispersive measurement of electron spin states in Coulomb-confined silicon double quantum dots

    NASA Astrophysics Data System (ADS)

    House, Matthew; Kobayashi, Takashi; Weber, Bent; Hile, Sam; Rogge, Sven; Simmons, Michelle

    2015-03-01

    We use radio frequency reflectometry with a resonant circuit to investigate a double quantum dot device patterned by the placement of phosphorus donors in silicon with scanning tunnelling microscope lithography. The circuit responds to electron tunnelling to and from the quantum dots, the complex admittance of which provides information about the tunnel coupling between the dots and the leads. With four electrons on two dots, the Pauli Exclusion Principle makes tunnelling of one electron between the two dots spin dependent, which we exploit to measure the electronic spin state. We map the ground state transition between singlet and triplet states as a function of electric and magnetic fields, which shows that the exchange energy can be tuned over an order of magnitude (about 10 to 100 μeV) or more in this device. We apply high frequency pulses to induce an excited spin state and observe that the dispersive measurement can detect the excited spin state in addition to the ground state.

  14. Gate induced superconductivity in layered material based electronic double layer field effect transistors

    NASA Astrophysics Data System (ADS)

    Ye, J. T.; Inoue, S.; Kobayashi, K.; Kasahara, Y.; Yuan, H. T.; Shimotani, H.; Iwasa, Y.

    2010-12-01

    Applying the principle of field effect transistor to layered materials provides new opportunities to manipulate their electronic properties for interesting sciences and applications. Novel gate dielectrics like electronic double layer (EDL) formed by ionic liquids are demonstrated to achieve an electrostatic surface charge accumulation on the order of 1014 cm-2. To realize electric field-induced superconductivity, we chose a layered compound: ZrNCl, which is known to be superconducting by introducing electrons through intercalation of alkali metals into the van der Waals gaps. A ZrNCl-based EDL transistor was micro fabricated on a thin ZrNCl single crystal made by mechanical micro-cleavage. Accumulating charges using EDL gate dielectrics onto the channel surface of ZrNCl shows effective field effect modulation of its electronic properties. Sheet resistance of ZrNCl EDL transistor is reduced by applying a gate voltage from 0 to 4.5 V. Temperature dependence of sheet resistance showed clear evidence of metal-insulator transition upon gating, observed at a gate voltage higher than 3.5 V. Furthermore, gate-induced superconductivity took place after metal-insulator transition when the transistor is cooled down to about 15 K.

  15. Degradation of InGaAs/InP double heterojunction bipolar transistors under electron irradiation

    SciTech Connect

    Bandyopadhyay, A.; Subramanian, S.; Chandrasekhar, S.; Dentai, A.G.; Goodnick, S.M.

    1999-05-01

    The dc characteristics of InGaAs/InP double heterojunction bipolar transistors (DHBT`s) are studied under high-energy ({approximately}1 MeV) electron irradiation up to a fluence of 14.8 {times} 10{sup 15} electrons/cm{sup 2}. The devices show an increase in common-emitter current gain (h{sub fe}) at low levels of dose (<10{sup 15} electrons/cm{sup 2}) and a gradual decrease in h{sub fe} and an increase in output conductance for higher doses. The decrease in h{sub fe} is as much as {approximately}80% at low base currents ({approximately}10 {micro}A) after a cumulative dose of 14.8 {times} 10{sup 15} electrons/cm{sup 2}. The observed degradation effects in collector current-voltage (I-V) characteristics are studied quantitatively using a simple SPICE-like device model. The overall decrease in h{sub fe} is attributed to increased recombination in the emitter-base junction region caused by radiation-induced defects. The defects introduced in the collector-base junction region are believed to be responsible for the observed increase in the output conductance.

  16. The second Born approximation for the double ionization of N2 by electron impact

    NASA Astrophysics Data System (ADS)

    Lamy, P.; Dal Cappello, C.; Charpentier, I.; Ruiz-Lopez, M. F.; Hervieux, P. A.

    2016-07-01

    In their (e,3e) and (e,3-1e) experiments of the double ionization (DI) of the outermost orbital of N2, Li et al (2012 J. Phys. B: At. Mol. Opt. Phys. 45 135201) recently showed that the process is largely dominated by a two-step-2 mechanism, which is a double interaction of the incident electron with the target. From a theoretical point of view, this should entail the use of the second Born approximation. In the past, very few theoretical calculations had been carried out this way because it requires a difficult numerical triple integration. We propose here to take into account the second Born approximation for the DI of N2 by using the closure approximation. The initial state is described by a single-center wave function derived from the usual multi-center wave function obtained in the self-consistent-field Hartree–Fock method using the linear combination of atomic orbitals-molecular orbital (LCAO-MO) approximation. The final state describes the interaction between each of the ejected electrons and the target by a Coulomb wave and the interaction between the two ejected electrons with the use of the Gamow factor. We calculate differential cross sections using the same kinematic conditions as Li et al (intermediate incident energy about 600 eV) for (e,3e) and (e,3-1e) DI of N2. The results show that the model does not allow a shift of the variation of the four-fold differential cross section near the momentum transfer to be obtained nor its opposite when we include the contribution given by the second Born approximation, as in (e,3-1e) experiments.

  17. Equatorial electron loss by double resonance with oblique and parallel intense chorus waves

    NASA Astrophysics Data System (ADS)

    Mourenas, D.; Artemyev, A. V.; Agapitov, O. V.; Mozer, F. S.; Krasnoselskikh, V. V.

    2016-05-01

    Puzzling satellite observations of butterfly pitch angle distributions and rapid dropouts of 30-150 keV electrons are widespread in the Earth's radiation belts. Several mechanisms have been proposed to explain these observations, such as enhanced outward radial diffusion combined with magnetopause shadowing or scattering by intense magnetosonic waves, but their effectiveness is mainly limited to storm times. Moreover, the scattering of 30-150 keV electrons via cyclotron resonance with intense parallel chorus waves should be limited to particles with equatorial pitch angle smaller than 70°-75°, leaving unaffected a large portion of the population. In this paper, we investigate the possible effects of oblique whistler mode waves, noting, in particular, that Landau resonance with very oblique waves can occur up to ˜89°. We demonstrate that such very oblique chorus waves with realistic amplitudes can very efficiently nonlinearly transport nearly equatorially mirroring electrons toward smaller pitch angles where nonlinear scattering (phase bunching) via cyclotron resonance with quasi-parallel waves can take over and quickly send them to much lower pitch angles <40°. The proposed double resonance mechanism could therefore explain the formation of butterfly pitch angle distributions as well as contribute to some fast dropouts of 30-150 keV electrons occurring during moderate geomagnetic disturbances at L = 4-6. Since 30-150 keV electrons represent a seed population for a further acceleration to relativistic energies by intense parallel chorus waves during storms or substorms, the proposed mechanism may have important consequences on the dynamics of 100 keV to MeV electron fluxes in the radiation belts.

  18. Dependence of distance distributions derived from double electron-electron resonance pulsed EPR spectroscopy on pulse-sequence time.

    PubMed

    Baber, James L; Louis, John M; Clore, G Marius

    2015-04-27

    Pulsed double electron-electron resonance (DEER) provides pairwise P(r) distance distributions in doubly spin labeled proteins. We report that in protonated proteins, P(r) is dependent on the length of the second echo period T owing to local environmental effects on the spin-label phase memory relaxation time Tm . For the protein ABD, this effect results in a 1.4 Å increase in the P(r) maximum from T=6 to 20 μs. Protein A has a bimodal P(r) distribution, and the relative height of the shorter distance peak at T=10 μs, the shortest value required to obtain a reliable P(r), is reduced by 40 % relative to that found by extrapolation to T=0. Our results indicate that data at a series of T values are essential for quantitative interpretation of DEER to determine the extent of the T dependence and to extrapolate the results to T=0. Complete deuteration (99 %) of the protein was accompanied by a significant increase in Tm and effectively abolished the P(r) dependence on T. PMID:25757985

  19. Probing the Structure of the Mechanosensitive Channel of Small Conductance in Lipid Bilayers with Pulsed Electron-Electron Double Resonance

    PubMed Central

    Ward, Richard; Pliotas, Christos; Branigan, Emma; Hacker, Christian; Rasmussen, Akiko; Hagelueken, Gregor; Booth, Ian R.; Miller, Samantha; Lucocq, John; Naismith, James H.; Schiemann, Olav

    2014-01-01

    Mechanosensitive channel proteins are important safety valves against osmotic shock in bacteria, and are involved in sensing touch and sound waves in higher organisms. The mechanosensitive channel of small conductance (MscS) has been extensively studied. Pulsed electron-electron double resonance (PELDOR or DEER) of detergent-solubilized protein confirms that as seen in the crystal structure, the outer ring of transmembrane helices do not pack against the pore-forming helices, creating an apparent void. The relevance of this void to the functional form of MscS in the bilayer is the subject of debate. Here, we report PELDOR measurements of MscS reconstituted into two lipid bilayer systems: nanodiscs and bicelles. The distance measurements from multiple mutants derived from the PELDOR data are consistent with the detergent-solution arrangement of the protein. We conclude, therefore, that the relative positioning of the transmembrane helices is preserved in mimics of the cell bilayer, and that the apparent voids are not an artifact of detergent solution but a property of the protein that will have to be accounted for in any molecular mechanism of gating. PMID:24559986

  20. Pulsed electron-electron double resonance spectroscopy between a high-spin Mn(2+) ion and a nitroxide spin label.

    PubMed

    Akhmetzyanov, D; Plackmeyer, J; Endeward, B; Denysenkov, V; Prisner, T F

    2015-03-14

    Pulsed Electron-Electron Double Resonance (PELDOR) has attracted considerable attention for biomolecular applications, as it affords precise measurements of distances between pairs of spin labels in the range of 1.5-8 nm. Usually nitroxide moieties incorporated by site-directed spin labelling with cysteine residues are used as spin probes in protein systems. Recently, naturally occurring cofactors and metal ions have also been explored as paramagnetic spin species for such measurements. In this work we investigate the performance of PELDOR between a nitroxide spin label and a high-spin Mn(2+) ion in a synthetic model compound at Q-band (34 GHz) and G-band (180 GHz). We demonstrate that the distances obtained with high-frequency PELDOR are in good agreement with structural predictions. At Q-band frequencies experiments have been performed by probing either the high-spin Mn(2+) ion or the nitroxide spin label. At G-band frequencies we have been able to detect changes in the dipolar oscillation frequency, depending on the pump-probe positions across the g-tensor resolved nitroxide EPR spectrum. These changes result from the restricted mobility of the nitroxide spin label in the model compound. Our results demonstrate that the high-spin Mn(2+) ion can be used for precise distance measurements and open the doors for many biological applications, as naturally occurring Mg(2+) sites can be readily exchanged for Mn(2+). PMID:25669744

  1. Probing the structure of the mechanosensitive channel of small conductance in lipid bilayers with pulsed electron-electron double resonance.

    PubMed

    Ward, Richard; Pliotas, Christos; Branigan, Emma; Hacker, Christian; Rasmussen, Akiko; Hagelueken, Gregor; Booth, Ian R; Miller, Samantha; Lucocq, John; Naismith, James H; Schiemann, Olav

    2014-02-18

    Mechanosensitive channel proteins are important safety valves against osmotic shock in bacteria, and are involved in sensing touch and sound waves in higher organisms. The mechanosensitive channel of small conductance (MscS) has been extensively studied. Pulsed electron-electron double resonance (PELDOR or DEER) of detergent-solubilized protein confirms that as seen in the crystal structure, the outer ring of transmembrane helices do not pack against the pore-forming helices, creating an apparent void. The relevance of this void to the functional form of MscS in the bilayer is the subject of debate. Here, we report PELDOR measurements of MscS reconstituted into two lipid bilayer systems: nanodiscs and bicelles. The distance measurements from multiple mutants derived from the PELDOR data are consistent with the detergent-solution arrangement of the protein. We conclude, therefore, that the relative positioning of the transmembrane helices is preserved in mimics of the cell bilayer, and that the apparent voids are not an artifact of detergent solution but a property of the protein that will have to be accounted for in any molecular mechanism of gating. PMID:24559986

  2. Femtosecond crystallography with ultrabright electrons and x-rays: capturing chemistry in action.

    PubMed

    Miller, R J Dwayne

    2014-03-01

    With the recent advances in ultrabright electron and x-ray sources, it is now possible to extend crystallography to the femtosecond time domain to literally light up atomic motions involved in the primary processes governing structural transitions. This review chronicles the development of brighter and brighter electron and x-ray sources that have enabled atomic resolution to structural dynamics for increasingly complex systems. The primary focus is on achieving sufficient brightness using pump-probe protocols to resolve the far-from-equilibrium motions directing chemical processes that in general lead to irreversible changes in samples. Given the central importance of structural transitions to conceptualizing chemistry, this emerging field has the potential to significantly improve our understanding of chemistry and its connection to driving biological processes. PMID:24604195

  3. Advanced Paramagnetic Resonance Spectroscopies of Iron-Sulfur Proteins: Electron Nuclear Double Resonance (ENDOR) and Electron Spin Echo Envelope Modulation (ESEEM)

    PubMed Central

    Cutsail, George E.; Telser, Joshua; Hoffman, Brian M.

    2015-01-01

    The advanced electron paramagnetic resonance (EPR) techniques, electron nuclear double resonance (ENDOR) and electron spin echo envelope modulation (ESEEM) spectroscopies, provide unique insights into the structure, coordination chemistry, and biochemical mechanism of Nature’s widely distributed iron-sulfur cluster (FeS) proteins. This review describes the ENDOR and ESEEM techniques and then provides a series of case studies on their application to a wide variety of FeS proteins including ferredoxins, nitrogenase, and radical SAM enzymes. PMID:25686535

  4. Doubly resonant three-photon double ionization of Ar atoms induced by an EUV free-electron laser

    SciTech Connect

    Gryzlova, E. V.; Ma, Ri; Fukuzawa, H.; Motomura, K.; Yamada, A.; Ueda, K.; Grum-Grzhimailo, A. N.; Strakhova, S. I.; Kabachnik, N. M.; Rouzee, A.; Hundermark, A.; Vrakking, M. J. J.; Johnsson, P.; Nagaya, K.; Yase, S.; Mizoguchi, Y.; Yao, M.; Nagasono, M.; Tono, K.; Yabashi, M.; and others

    2011-12-15

    A mechanism for three-photon double ionization of atoms by extreme-ultraviolet free-electron laser pulses is revealed, where in a sequential process the second ionization step, proceeding via resonant two-photon ionization of ions, is strongly enhanced by the excitation of ionic autoionizing states. In contrast to the conventional model, the mechanism explains the observed relative intensities of photoelectron peaks and their angular dependence in three-photon double ionization of argon.

  5. Asymmetry and non-adiabaticity in fragmentation of disulfide bonds upon electron capture.

    PubMed

    Gámez, José A; Serrano-Andrés, Luis; Yáñez, Manuel

    2010-08-23

    Although it has been generally assumed that electron attachment to disulfide derivatives leads to a systematic and significant activation of the S-S bond, we show, by using [CH(3)SSX] (X = CH(3), NH(2), OH, F) derivatives as model compounds, that this is the case only when the X substituents have low electronegativity. Through the use of MP2, QCI and CASPT2 molecular orbital (MO) methods, we elucidate, for the first time, the mechanisms that lead to unimolecular fragmentation of disulfide derivatives after electron attachment. Our theoretical scrutiny indicates that these mechanisms are more intricate than assumed in previous studies. The most stable products, from a thermodynamic viewpoint, correspond to the release of neutral molecules; CH(4), NH(3), H(2)O, and HF. However, the barriers to reach these products depend strongly on the electronegativity of the X substituents. Only for very electronegative substituents, such as OH or F, the loss of H(2)O or HF is the most favorable process, and likely the only one observed. This is possible because of two concomitant factors, 1) the extra electron for [CH(3)SSX](-) (X = OH, F) occupies a sigma*(S-X) MO, which favors the cleavage of the S-X bond, and 2) the activation barriers associated with the hydrogen transfer process to produce H(2)O and HF are rather low. Only when the substituents are less electronegative (X = H, CH(3), NH(2)) the extra electron is located in a sigma*(S-S) orbital and the cleavage of the disulfide bridge becomes the most favorable process. The intimate mechanism associated with the S-S bond dissociation process also depends strongly on the nature of the substituent. For X = H or CH(3) the process is strictly adiabatic, while for X = NH(2) it proceeds through a conical intersection (CI) associated with the charge reorganization necessary to obtain, from a molecular anion with the extra electron delocalized in a sigma*(S-S) antibonding orbital, two fragments with the proper charge localization

  6. The double ionization of H{sub 2} by fast electron impact: Influence of the final state electron-electron correlation

    SciTech Connect

    Chuluunbaatar, O. Gusev, A. A.; Joulakian, B. B.

    2013-02-15

    We have determined fully differential cross sections of the (e, 3e) double ionization of H{sub 2} by employing correlated initial- and final-state wave functions. We have constructed for the description of the two slow ejected electrons a symmetrized product of a correlation function and two-center continuum wave functions, which fulfill the correct boundary conditions asymptotically up to the order O((kr){sup -2}). We have shown that the introduction of the correlated part of the final-state wave function improves the results on the (e, 3-1e) of H{sub 2}.

  7. Energy Doubling of 42 GeV Electrons in a Meter-scale Plasma Wakefield Accelerator

    SciTech Connect

    Blumenfeld, Ian; Clayton, Christopher E.; Decker, Franz-Josef; Hogan, Mark J.; Huang, Chengkun; Ischebeck, Rasmus; Iverson, Richard; Joshi, Chandrashekhar; Katsouleas, Thomas; Kirby, Neil; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; Muggli, Patric; Oz, Erdem; Siemann, Robert H.; Walz, Dieter; Zhou, Miaomiao; /SLAC /UCLA /Southern California U.

    2007-03-14

    The energy frontier of particle physics is several trillion electron volts, but colliders capable of reaching this regime (such as the Large Hadron Collider and the International Linear Collider) are costly and time-consuming to build; it is therefore important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators, a drive beam (either laser or particle) produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultrahigh accelerating fields over a substantial length to achieve a significant energy gain. Here we show that an energy gain of more than 42 GeV is achieved in a plasma wakefield accelerator of 85 cm length, driven by a 42 GeV electron beam at the Stanford Linear Accelerator Center (SLAC). The results are in excellent agreement with the predictions of three-dimensional particle-in-cell simulations. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of {approx} 52GV m{sup -1}. This effectively doubles their energy, producing the energy gain of the 3-km-long SLAC accelerator in less than a meter for a small fraction of the electrons in the injected bunch. This is an important step towards demonstrating the viability of plasma accelerators for high-energy physics applications.

  8. Spin-mapping of coal structures with ESE and ENDOR (Electron-Nuclear Double Resonance)

    SciTech Connect

    Belford, R.L.; Clarkson, R.B.

    1989-03-01

    Our Laboratory is presently engaged in developing a method to model sulfur-containing compounds in whole coal. It has been established that most of the organic sulfur in coal exists in the form of aromatic groups known as thiophenes. Sulfur-containing aromatic compounds such as thiophene, tetraphenylthiophene and thianthrene were adsorbed onto silica-alumina catalyst surfaces were used as models to emulate coal's anisotropic nature and abundance of unpaired electron spin density. The spectroscopic techniques used were Electron Paramagnetic Resonance (EPR), Electron-Nuclear Double Resonance (ENDOR). EPR spectroscopy is a well established method to characterize g-matrix anisotropy in transition metal compounds. With increased resolution, EPR has become very useful for characterizing the small but still detectable g-matrix anisotropy in organic systems such as coal and the model systems for coal. ENDOR spectroscopy involves the inducement of NMR transitions of the nearby protons while detecting them with an EPR detection scheme which is several orders of magnitude more sensitive than using a NMR detection scheme. Analysis of the ENDOR spectra produced hyperfine information which is characteristic of these sulfur-containing systems. This information will be needed to resolve anisotropic hyperfine spectral features attributable to sulfur content in the analysis of coal macerals. 2 refs., 3 figs.

  9. Enhancement of multisubband electron mobility in parabolic AlxGa1-xAs-GaAs double quantum well structures

    NASA Astrophysics Data System (ADS)

    Sahu, Trinath; Palo, Sangeeta; Panda, A. K.

    2013-02-01

    We analyze the low temperature multisubband electron mobility in AlxGa1-xAs-GaAs parabolic double quantum well structures in which the outer barriers are delta doped with Si. The structural parabolic potential, obtained from gradual variation of the alloy fraction x (from 0 to xp), partly compensates the triangular like potential profile near the outer interfaces inducing the electrons to move towards the centre of the wells. We study the effect of interplay of ionized impurity (II) scattering and alloy disorder (AD) scattering on the subband mobility. We show that when single subband is occupied both II- and AD-scatterings govern the mobility. However, once second subband is occupied, the mobility is influenced by II-scattering mediated by intersubband effects. It is gratifying to show that the mobility is considerably enhanced in parabolic double quantum wells (0.3 ≥ xp > 0) compared to the square double quantum well structures (xp = 0) at large well widths where double subband is occupied. By increasing the electron density (Ns), the enhancement increases further. We also show that in case of a parabolic single quantum well structure large enhancement in mobility is obtained compared to that of square single quantum well structure as long as single subband is occupied, unlike the double quantum well systems. Our results of mobility in parabolic double quantum wells can be utilized for low temperature device applications.

  10. Effects of electron cyclotron current drive on the evolution of double tearing mode

    SciTech Connect

    Sun, Guanglan Dong, Chunying; Duan, Longfang

    2015-09-15

    The effects of electron cyclotron current drive (ECCD) on the double tearing mode (DTM) in slab geometry are investigated by using two-dimensional compressible magnetohydrodynamics equations. It is found that, mainly, the double tearing mode is suppressed by the emergence of the secondary island, due to the deposition of driven current on the X-point of magnetic island at one rational surface, which forms a new non-complete symmetric magnetic topology structure (defined as a non-complete symmetric structure, NSS). The effects of driven current with different parameters (magnitude, initial time of deposition, duration time, and location of deposition) on the evolution of DTM are analyzed elaborately. The optimal magnitude or optimal deposition duration of driven current is the one which makes the duration of NSS the longest, which depends on the mutual effect between ECCD and the background plasma. Moreover, driven current introduced at the early Sweet-Parker phase has the best suppression effect; and the optimal moment also exists, depending on the duration of the NSS. Finally, the effects varied by the driven current disposition location are studied. It is verified that the favorable location of driven current is the X-point which is completely different from the result of single tearing mode.

  11. Proton electron double resonance imaging (PEDRI) of the isolated beating rat heart.

    PubMed

    Liebgott, Thibaut; Li, Haihong; Deng, Yuanmu; Zweier, Jay L

    2003-08-01

    Proton electron double resonance imaging (PEDRI) is a double resonance technique where proton MRI is performed with irradiation of a paramagnetic solute. A low-field PEDRI system was developed at 20.1 mT suitable for imaging free radicals in biological samples. With a new small dual resonator, PEDRI was applied to image nitroxide free radicals in isolated beating rat hearts. Experiments with phantoms showed maximum image enhancement factors (IEF) of 42 or 28 with TEMPONE radical concentrations of 2-3 mM at EPR irradiation powers of 12W or 6W, respectively. In the latter case, image resolution better than 0.5 mm and radical sensitivity of 5 microM was obtained. For isolated heart studies, EPR irradiation power of 6W provided optimal compromise of modest sample heating with good SNR. Only a small increase in temperature of about 1 degrees C was observed, while cardiac function remained within 10% of control values. With infusion of 3 mM TEMPONE an IEF of 15 was observed enabling 2D or 3D images to be obtained in 27 sec or 4.5 min, respectively. These images visualized the change in radical distribution within the heart during infusion and clearance. Thus, PEDRI enables rapid and high-quality imaging of free radical uptake and clearance in perfused hearts and provides a useful technique for studying cardiac radical metabolism. PMID:12876716

  12. Kuang's Semi-Classical Formalism for Calculating Electron Capture Cross Sections: A Space- Physics Application

    NASA Technical Reports Server (NTRS)

    Barghouty, A. F.

    2014-01-01

    Accurate estimates of electroncapture cross sections at energies relevant to the modeling of the transport, acceleration, and interaction of energetic neutral atoms (ENA) in space (approximately few MeV per nucleon) and especially for multi-electron ions must rely on detailed, but computationally expensive, quantum-mechanical description of the collision process. Kuang's semi-classical approach is an elegant and efficient way to arrive at these estimates. Motivated by ENA modeling efforts for apace applications, we shall briefly present this approach along with sample applications and report on current progress.

  13. Angular correlations in radiative cascades following resonant electron capture by highly charged ions

    SciTech Connect

    Matula, O.; Surzhykov, A.; Fritzsche, S.; Currell, F. J.

    2011-11-15

    We investigate the angular correlations between the photons emitted in the dielectronic recombination (DR) of initially hydrogenlike heavy ions. The theoretical analysis is performed based on a density-matrix approach and Dirac's relativistic theory. Special emphasis has been placed upon the effects of the higher-order, nondipole terms in the expansion of the electron-photon interaction. To illustrate these effects, we present and discuss detailed calculations for K-LL DR of initially hydrogenlike xenon, gold, and uranium. These computations show that the angular correlations are significantly affected by interference between the leading electric-dipole (E1) and the magnetic-quadrupole (M2) transitions.

  14. Equation-of-motion coupled cluster method for high spin double electron attachment calculations

    SciTech Connect

    Musiał, Monika Lupa, Łukasz; Kucharski, Stanisław A.

    2014-03-21

    The new formulation of the equation-of-motion (EOM) coupled cluster (CC) approach applicable to the calculations of the double electron attachment (DEA) states for the high spin components is proposed. The new EOM equations are derived for the high spin triplet and quintet states. In both cases the new equations are easier to solve but the substantial simplification is observed in the case of quintets. Out of 21 diagrammatic terms contributing to the standard DEA-EOM-CCSDT equations for the R{sub 2} and R{sub 3} amplitudes only four terms survive contributing to the R{sub 3} part. The implemented method has been applied to the calculations of the excited states (singlets, triplets, and quintets) energies of the carbon and silicon atoms and potential energy curves for selected states of the Na{sub 2} (triplets) and B{sub 2} (quintets) molecules.

  15. Optical and electronic properties of double perovskite Ba2ScSbO6

    NASA Astrophysics Data System (ADS)

    Ray, Rajyavardhan; Himanshu, A. K.; Lahiri, J.; Kumar, Uday; Sen, Pintu; Bandyopadhyay, S. K.; Sinha, T. P.

    2016-05-01

    The ordered double perovskite Ba2ScSbO6 (BSS) has been synthesized in polycrystalline form by solid state reaction at 1400 C for 72 Hrs. Structural characterization of the compound was done through X-ray diffraction (XRD) followed by Rietveld analysis. The crystal structure is cubic, with space group Fm-3m (No. 225) and lattice parameter, a = 8.20 Ǻ. Optical band-gap has been calculated using UV-Vis Spectroscopy and Kubelka-Munk (KM) function, yielding 4.23 eV. A detailed Ab-initio Density Functional Theory (DFT) study of the electronic properties has been carried out using the Full-Potential Linear Augmented Plane Wave (FP-LAPW) as implemented in WIEN2k. BSS is found to be a large band-gap insulator with potential technological applications.

  16. Effect of interdots electronic repulsion in the Majorana signature for a double dot interferometer

    NASA Astrophysics Data System (ADS)

    Ricco, L. S.; Marques, Y.; Dessotti, F. A.; de Souza, M.; Seridonio, A. C.

    2016-04-01

    We investigate theoretically the features of the Majorana hallmark in the presence of Coulomb repulsion between two quantum dots describing a spinless double dot interferometer, where one of the dots is strongly coupled to a Kitaev wire within the topological phase. Such a system has been originally proposed without Coulomb interaction in Dessotti et al. (2014 [16]) . Our findings reveal that for dots in resonance, the ratio between the strength of Coulomb repulsion and the dot-wire coupling changes the width of the Majorana zero-bias peak for both Fano regimes studied, indicating thus that the electronic interdots correlation influences the Majorana state lifetime in the dot hybridized with the wire. Moreover, for the off-resonance case, the swap between the energy levels of the dots also modifies the width of the Majorana peak, which does not happen for the noninteracting case. The results obtained here can guide experimentalists that pursuit a way of revealing Majorana signatures.

  17. First measurement of electron temperature from signal ratios in a double-pass Thomson scattering system

    SciTech Connect

    Tojo, H.; Itami, K.; Hatae, T.; Ejiri, A.; Yamaguchi, T.; Takase, Y.; Hiratsuka, J.

    2012-02-15

    This paper presents an experimental demonstration to determine electron temperature (T{sub e}) with unknown spectral sensitivity (transmissivity) in a Thomson scattering system. In this method, a double-pass scattering configuration is used and the scattered lights from each pass (with different scattering angles) are measured separately. T{sub e} can be determined from the ratio of the signal intensities without knowing a real chromatic dependence in the sensitivity. Note that the wavelength range for each spectral channel must be known. This method was applied to the TST-2 Thomson scattering system. As a result, T{sub e} measured from the ratio (T{sub e,r}) and T{sub e} measured from a standard method (T{sub e,s}) showed a good agreement with <|T{sub e,r}-T{sub e,s}|/T{sub e,s}>= 7.3%.

  18. High-fidelity ac gate operations of a three-electron double quantum dot qubit

    NASA Astrophysics Data System (ADS)

    Wong, Clement H.

    2016-01-01

    Semiconductor quantum dots in silicon are promising qubits because of long spin coherence times and their potential for scalability. However, such qubits with complete electrical control and fidelities above the threshold for quantum error correction have not yet been achieved. We show theoretically that the threshold fidelity can be achieved with ac gate operation of the quantum dot hybrid qubit. Formed by three electrons in a double dot, this qubit is electrically controlled, does not require magnetic fields, and runs at gigahertz (GHz) gate speeds. We analyze the decoherence caused by 1 /f charge noise in this qubit, find parameters that minimize the charge noise dependence in the qubit frequency, and determine the optimal working points for ac gate operations that drive the detuning and tunnel coupling.

  19. Oscillation of electron mobility in parabolic double quantum well structure due to applied electric field

    SciTech Connect

    Sahoo, Narayan; Sahu, Trinath

    2014-12-15

    We show that oscillation of low temperature electron mobility μ can be obtained by applying an electric field F along the growth direction of the asymmetrically barrier delta doped Al{sub x}Ga{sub 1-x}As parabolic double quantum well structure. The drastic changes in the subband Fermi energies and distributions of subband wave functions as a function of F yield nonmonotonic intra- and intersubband scattering rate matrix elements mediated by intersubband effects. The oscillatory enhancement of μ, which is attributed to the subband mobilities governed by the ionized impurity scattering, magnifies with increase in well width and decrease in height of the parabolic structure potential. The results can be utilized for nanoscale low temperature device applications.

  20. Full coupled cluster singles, doubles and triples model for the description of electron correlation

    SciTech Connect

    Hoffmann, M.R.

    1984-10-01

    Equations for the determination of the cluster coefficients in a full coupled cluster theory involving single, double and triple cluster operators with respect to an independent particle reference, expressible as a single determinant of spin-orbitals, are derived. The resulting wave operator is full, or untruncated, consistant with the choice of cluster operator truncation and the requirements of the connected cluster theorem. A time-independent diagrammatic approach, based on second quantization and the Wick theorem, is employed. Final equations are presented that avoid the construction of rank three intermediary tensors. The model is seen to be a computationally viable, size-extensive, high-level description of electron correlation in small polyatomic molecules.

  1. S-model calculations for high-energy-electron-impact double ionization of helium

    NASA Astrophysics Data System (ADS)

    Gasaneo, G.; Mitnik, D. M.; Randazzo, J. M.; Ancarani, L. U.; Colavecchia, F. D.

    2013-04-01

    In this paper the double ionization of helium by high-energy electron impact is studied. The corresponding four-body Schrödinger equation is transformed into a set of driven equations containing successive orders in the projectile-target interaction. The transition amplitude obtained from the asymptotic limit of the first-order solution is shown to be equivalent to the familiar first Born approximation. The first-order driven equation is solved within a generalized Sturmian approach for an S-wave (e,3e) model process with high incident energy and small momentum transfer corresponding to published measurements. Two independent numerical implementations, one using spherical and the other hyperspherical coordinates, yield mutual agreement. From our ab initio solution, the transition amplitude is extracted, and single differential cross sections are calculated and could be taken as benchmark values to test other numerical methods in a previously unexplored energy domain.

  2. Counter-diabatic driving for fast spin control in a two-electron double quantum dot

    PubMed Central

    Ban, Yue; Chen, Xi

    2014-01-01

    The techniques of shortcuts to adiabaticity have been proposed to accelerate the “slow” adiabatic processes in various quantum systems with the applications in quantum information processing. In this paper, we study the counter-diabatic driving for fast adiabatic spin manipulation in a two-electron double quantum dot by designing time-dependent electric fields in the presence of spin-orbit coupling. To simplify implementation and find an alternative shortcut, we further transform the Hamiltonian in term of Lie algebra, which allows one to use a single Cartesian component of electric fields. In addition, the relation between energy and time is quantified to show the lower bound for the operation time when the maximum amplitude of electric fields is given. Finally, the fidelity is discussed with respect to noise and systematic errors, which demonstrates that the decoherence effect induced by stochastic environment can be avoided in speeded-up adiabatic control. PMID:25174453

  3. Determining the Binding Sites of β-Cyclodextrin and Peptides by Electron-Capture Dissociation High Resolution Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Qi, Yulin; Geib, Timon; Volmer, Dietrich A.

    2015-07-01

    Cyclodextrins (CDs) are a group of cyclic oligosaccharides, which readily form inclusion complexes with hydrophobic compounds to increase bioavailability, thus making CDs ideal drug excipients. Recent studies have also shown that CDs exhibit a wide range of protective effects, preventing proteins from aggregation, degradation, and folding. These effects strongly depend on the binding sites on the protein surface. CDs only exhibit weak interactions with amino acids, however; conventional analytical techniques therefore usually fail to reveal the exact location of the binding sites. Moreover, some studies even suggest that CD inclusion complexes are merely electrostatic adducts. Here, electron capture dissociation (ECD) was applied in this proof-of-concept study to examine the exact nature of the CD/peptide complexes, and CD binding sites were unambiguously located for the first time via Fourier-transform ion cyclotron resonance (FTICR) tandem mass spectrometry.

  4. A Novel Feature Extraction Approach Using Window Function Capturing and QPSO-SVM for Enhancing Electronic Nose Performance

    PubMed Central

    Guo, Xiuzhen; Peng, Chao; Zhang, Songlin; Yan, Jia; Duan, Shukai; Wang, Lidan; Jia, Pengfei; Tian, Fengchun

    2015-01-01

    In this paper, a novel feature extraction approach which can be referred to as moving window function capturing (MWFC) has been proposed to analyze signals of an electronic nose (E-nose) used for detecting types of infectious pathogens in rat wounds. Meanwhile, a quantum-behaved particle swarm optimization (QPSO) algorithm is implemented in conjunction with support vector machine (SVM) for realizing a synchronization optimization of the sensor array and SVM model parameters. The results prove the efficacy of the proposed method for E-nose feature extraction, which can lead to a higher classification accuracy rate compared to other established techniques. Meanwhile it is interesting to note that different classification results can be obtained by changing the types, widths or positions of windows. By selecting the optimum window function for the sensor response, the performance of an E-nose can be enhanced. PMID:26131672

  5. A Novel Feature Extraction Approach Using Window Function Capturing and QPSO-SVM for Enhancing Electronic Nose Performance.

    PubMed

    Guo, Xiuzhen; Peng, Chao; Zhang, Songlin; Yan, Jia; Duan, Shukai; Wang, Lidan; Jia, Pengfei; Tian, Fengchun

    2015-01-01

    In this paper, a novel feature extraction approach which can be referred to as moving window function capturing (MWFC) has been proposed to analyze signals of an electronic nose (E-nose) used for detecting types of infectious pathogens in rat wounds. Meanwhile, a quantum-behaved particle swarm optimization (QPSO) algorithm is implemented in conjunction with support vector machine (SVM) for realizing a synchronization optimization of the sensor array and SVM model parameters. The results prove the efficacy of the proposed method for E-nose feature extraction, which can lead to a higher classification accuracy rate compared to other established techniques. Meanwhile it is interesting to note that different classification results can be obtained by changing the types, widths or positions of windows. By selecting the optimum window function for the sensor response, the performance of an E-nose can be enhanced. PMID:26131672

  6. The origin of the Crab Nebula and the electron capture supernova in 8-10 M solar mass stars

    NASA Technical Reports Server (NTRS)

    Nomoto, K.

    1981-01-01

    The chemical composition of the Crab Nebula is compared with several presupernova models. The small carbon and oxygen abundances in the helium-rich nebula are consistent with only the presupernova model of the star whose main sequence mass was MMS approximately 8-9.5 M. More massive stars contain too much carbon in the helium layer and smaller mass stars do not leave neutron stars. The progenitor star of the Crab Nebula lost appreciable part of the hydrogen-rich envelope before the hydrogen-rich and helium layers were mixed by convection. Finally it exploded as the electron capture supernova; the O+Ne+Mg core collapsed to form a neutron star and only the extended helium-rich envelope was ejected by the weak shock wave.

  7. A Mobile App for Securely Capturing and Transferring Clinical Images to the Electronic Health Record: Description and Preliminary Usability Study

    PubMed Central

    Emani, Srinivas; Carlile, Narath; Rosenthal, David I; Semakov, Simon; Pallin, Daniel J; Poon, Eric G

    2015-01-01

    Background Photographs are important tools to record, track, and communicate clinical findings. Mobile devices with high-resolution cameras are now ubiquitous, giving clinicians the opportunity to capture and share images from the bedside. However, secure and efficient ways to manage and share digital images are lacking. Objective The aim of this study is to describe the implementation of a secure application for capturing and storing clinical images in the electronic health record (EHR), and to describe initial user experiences. Methods We developed CliniCam, a secure Apple iOS (iPhone, iPad) application that allows for user authentication, patient selection, image capture, image annotation, and storage of images as a Portable Document Format (PDF) file in the EHR. We leveraged our organization’s enterprise service-oriented architecture to transmit the image file from CliniCam to our enterprise clinical data repository. There is no permanent storage of protected health information on the mobile device. CliniCam also required connection to our organization’s secure WiFi network. Resident physicians from emergency medicine, internal medicine, and dermatology used CliniCam in clinical practice for one month. They were then asked to complete a survey on their experience. We analyzed the survey results using descriptive statistics. Results Twenty-eight physicians participated and 19/28 (68%) completed the survey. Of the respondents who used CliniCam, 89% found it useful or very useful for clinical practice and easy to use, and wanted to continue using the app. Respondents provided constructive feedback on location of the photos in the EHR, preferring to have photos embedded in (or linked to) clinical notes instead of storing them as separate PDFs within the EHR. Some users experienced difficulty with WiFi connectivity which was addressed by enhancing CliniCam to check for connectivity on launch. Conclusions CliniCam was implemented successfully and found to be easy

  8. Comparative analysis of dioxins and furans by electron impact, high-resolution mass spectrometry and by electron capture, negative ionization, low-resolution mass spectrometry

    SciTech Connect

    Koester, C.J.; Harless, R.L.; Hites, R.A.

    1990-01-01

    Electron impact, high resolution mass spectrometry (HRMS) is currently the method of choice for the analysis of polychlorinated dibenso-p-dioxins and dibenzofurans (PCDD/F) because of its ability to detect PCDD/F in the presence of interfering compounds, such as polychlorinated biphenyls (PCB), which cannot be resolved by low resolution methods. The PDCC/F analyses may also be performed using electron capture, negative ionization (ECNI) low resolution mass spectrometry, providing extensive sample preparation is done to remove interferences. Before ECNI low resolution mass spectrometry (MS) can be accepted as a routine method for PCDD/F analysis, it is necessary to show that results generated by this method are comparable to those obtained by HRMS. Known mixtures and unknown air samples were analyzed by electron impact HRMS (Finnigan MAT 90 system) and by ECNI low resolution MS (Hewlett Packard 5985B). Both instruments were fitted with a gas chromatographic inlet. The PCDD/F concentrations determined by the two techniques compare favorably, typically within 20%. The major difference between these two methods is that the ECNI low resolution method shows poor sensitivity in detecting 2,3,7,8-tetrachlorodioxin. However, ECNI MS offers the advantage of lower detection limits (50-100 fg) than electron impact HRMS (0.1 to 0.5 pg). These results suggest that ECNI low resolution MS can be a simple, low cost alternative to the common high resolution methods used for PCDD/F analysis.

  9. Electron capture decay of cosmic rays: A model of the inhomogeneous interstellar medium

    NASA Technical Reports Server (NTRS)

    Letaw, J. R.; Silberberg, R.; Tsao, C. H.

    1985-01-01

    Traditional analyses of cosmic ray composition seek to identify the sources through a determination of a the isotopic abundances of these nuclei prior to acceleration. At the same time, it is both necessary and interesting to understand the nature of the medium through which cosmic rays pass before arriving at detectors. In fact, only within a model of the interstellar medium (ISM) sampled by cosmic rays can a refined estimate of source composition be made. An elaboration of the traditional model of the ISM used in studying cosmic ray propagation is explored. Inhomogeneity of the ISM is accomodated in this model. Within this model it is found that the abundances of some electron apture isotopes, are very sensitive to density inhomogeneities which might be expected in the ISM. These nuclei therefore measure the penetration of heavy cosmic rays into interstellar clouds.

  10. Dynamics of soft Nanomaterials captured by transmission electron microscopy in liquid water

    SciTech Connect

    Proetto, Maria T.; Rush, Anthony M.; Chien, Miao-Ping; Abellan Baeza, Patricia; Patterson, Joseph P.; Thompson, Matthew P.; Olson, Norman H.; Moore, Curtis E.; Rheingold, Arnold L.; Andolina, Christopher; Millstone, Jill; Howell, Stephen B.; Browning, Nigel D.; Evans, James E.; Gianneschi, Nathan C.

    2014-01-14

    In this paper we present in situ transmission electron microscopy (TEM) of soft, synthetic nanoparticles with a comparative analysis using conventional TEM methods. This comparison is made with the simple aim of describing what is an unprecedented example of in situ imaging by TEM. However, we contend the technique will quickly become essential in the characterization of analogous systems, especially where dynamics are of interest in the solvated state. In this case, particles were studied which were obtained from the direct polymerization of an oxaliplatin analog, designed for an ongoing program in novel chemotherapeutic delivery systems. The resulting nanoparticles provided sufficient contrast for facile imaging in situ, and point toward key design parameters that enable this new characterization approach for organic nanomaterials. We describe the preparation of the synthetic micellar nanoparticles to- gether with their characterization in liquid water.

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

    PubMed

    Uchida, Tsutomu; Oshita, Seiichi; Ohmori, Masayuki; Tsuno, Takuo; Soejima, Koichi; Shinozaki, Satoshi; Take, Yasuhisa; Mitsuda, Koichi

    2011-01-01

    Unique properties of micro- and nanobubbles (MNBs), such as a high adsorption of impurities on their surface, are difficult to verify because MNBs are too small to observe directly. We thus used a transmission electron microscope (TEM) with the freeze-fractured replica method to observe oxygen (O2) MNBs in solutions. MNBs in pure water and in 1% NaCl solutions were spherical or oval. Their size distribution estimated from TEM images close to that of the original solution is measured by light-scattered methods. When we applied this technique to the observation of O2 MNBs formed in the wastewater of a sewage plant, we found the characteristic features of spherical MNBs that adsorbed surrounding impurity particles on their surface.PACS: 68.03.-g, 81.07.-b, 92.40.qc. PMID:21711798

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

    NASA Astrophysics Data System (ADS)

    Uchida, Tsutomu; Oshita, Seiichi; Ohmori, Masayuki; Tsuno, Takuo; Soejima, Koichi; Shinozaki, Satoshi; Take, Yasuhisa; Mitsuda, Koichi

    2011-12-01

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

  13. Electronic Capture of Written Handoff Information: What Are the Next Steps?

    PubMed

    Nabors, Christopher; Khera, Sahil; Forman, Leanne; Kolte, Dhaval; Mittal, Varun; Marballi, Abhishek; Agrawal, Sahil; Pawar, Rahul; OʼConnell, Daniel; Afanador, Sara M; Kolandaivel, Krishna; Chugh, Savneek; Peterson, Stephen J

    2016-01-01

    Communication lapses during patient care transitions are reported to be frequent and may result in patient harm. The primary objective of our study was to assess the completeness, accuracy, and usefulness of our electronic handoff system to guide future software changes and educational interventions. We randomly selected and reviewed 707 of 2840 available handoff records generated on the medicine service of an academic medical center between August 1, 2012 and December 31, 2012. We used both quantitative and qualitative analytical techniques to characterize sign-outs in the following dimensions: completeness, usefulness and accuracy of information content, handoff task category, logic, internal consistency and appropriateness of assigned tasks, and composition and complexity of assigned tasks. The degree of completeness of information varied considerably across domains. Completeness was highest for entry of assigned tasks (99.9%), nearly as high for hospital course/presenting illness (95%), and relatively high (87%-98%) for entry of provider name and contact information, principal diagnosis, allergies, current clinical condition, mental status, and code status. Eighty-eight percent written handoffs described clinical condition and hospital course and whether there were tasks to complete. In 58% of suitable records, all problems listed in the electronic health record (EHR) were also present in the history of present illness. The accuracy of entered information also displayed wide variation. Only 80% of cardiovascular medications matched the contemporaneous EHR pharmacy record. Birth dates and allergies were identical in the handoff system and EHR in 95% and 86% of respective records. Of assigned tasks, 8% contained at least 1 unnecessary component or illogical/internally inconsistent element. Use of a handoff system, which organizes information entry through a standard template, promotes completeness of written handoff information. Inaccuracies in handoff data are

  14. Experimental determination of the hole capture kinetics of H4F deep trap in electron-irradiated highly doped p-type InP

    NASA Astrophysics Data System (ADS)

    Darwich, R.; Massarani, B.

    2004-07-01

    The hole capture kinetics of the main trap H4F in electron-irradiated p-type InP has been investigated by experimentally determining the exponential and nonexponential parts. The contribution of the slow part of the total kinetics is about 30% in our samples. An indication to a possible capture rate enhancement due to the electric field in the space-charge region is pointed out.

  15. Double ionization of the water molecule: Influence of the target orientation on the secondary-electron angular distributions

    SciTech Connect

    Oubaziz, D.; Aouchiche, H.; Champion, C.

    2011-01-15

    Fivefold differential cross sections for electron-induced double ionization of isolated oriented water molecules are reported. The theoretical investigation is performed within the first Born approximation by describing the initial molecular state by means of single-center wave functions. The contributions of each final state to the double-ionization process, i.e., with target electrons ejected from similar and/or different molecular subshells, are studied and compared in terms of shape and magnitude. Furthermore, for the particular target orientations investigated, we identify clearly the signature of the main scenarios involved in (e,3e) reactions, namely, the shake-off and the two-step 1 mechanisms.

  16. Photo-electron double regulated resistive switching memory behaviors of Ag/CuWO4/FTO device

    NASA Astrophysics Data System (ADS)

    Sun, B.; Jia, X. J.; Wu, J. H.; Chen, P.

    2015-12-01

    In this work, the CuWO4 film based resistive switching memory capacitors were fabricated with hydrothermal and spin-coating approaches. The device exhibits excellent photo-electron double controlled resistive switching memory characteristics with OFF/ON resistance ratio of ~103. It is believed that the interface of CuWO4 and FTO is responsible for such a switching behavior and it can be described by the Schottky-like barriers model. This study is useful for exploring the multifunctional materials and their applications in photo-electron double controlled nonvolatile memory devices.

  17. Mapping protein conformational heterogeneity under pressure with site-directed spin labeling and double electron-electron resonance.

    PubMed

    Lerch, Michael T; Yang, Zhongyu; Brooks, Evan K; Hubbell, Wayne L

    2014-04-01

    The dominance of a single native state for most proteins under ambient conditions belies the functional importance of higher-energy conformational states (excited states), which often are too sparsely populated to allow spectroscopic investigation. Application of high hydrostatic pressure increases the population of excited states for study, but structural characterization is not trivial because of the multiplicity of states in the ensemble and rapid (microsecond to millisecond) exchange between them. Site-directed spin labeling in combination with double electron-electron resonance (DEER) provides long-range (20-80 Å) distance distributions with angstrom-level resolution and thus is ideally suited to resolve conformational heterogeneity in an excited state populated under high pressure. DEER currently is performed at cryogenic temperatures. Therefore, a method was developed for rapidly freezing spin-labeled proteins under pressure to kinetically trap the high-pressure conformational ensemble for subsequent DEER data collection at atmospheric pressure. The methodology was evaluated using seven doubly-labeled mutants of myoglobin designed to monitor selected interhelical distances. For holomyoglobin, the distance distributions are narrow and relatively insensitive to pressure. In apomyoglobin, on the other hand, the distributions reveal a striking conformational heterogeneity involving specific helices in the pressure range of 0-3 kbar, where a molten globule state is formed. The data directly reveal the amplitude of helical fluctuations, information unique to the DEER method that complements previous rate determinations. Comparison of the distance distributions for pressure- and pH-populated molten globules shows them to be remarkably similar despite a lower helical content in the latter. PMID:24707053

  18. Conformational Cycle of the Vitamin B12 ABC Importer in Liposomes Detected by Double Electron-Electron Resonance (DEER)*

    PubMed Central

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

    2014-01-01

    Double electron-electron resonance is used here to investigate intermediates of the transport cycle of the Escherichia coli vitamin B12 ATP-binding cassette importer BtuCD-F. Previously, we showed the ATP-induced opening of the cytoplasmic gate I in TM5 helices, later confirmed by the AMP-PNP-bound BtuCD-F crystal structure. Here, other key residues are analyzed in TM10 helices (positions 307 and 322) and in the cytoplasmic gate II, i.e. the loop between TM2 and TM3 (positions 82 and 85). Without BtuF, binding of ATP induces detectable changes at positions 307 and 85 in BtuCD in liposomes. Together with BtuF, ATP triggers the closure of the cytoplasmic gate II in liposomes (reported by both positions 82 and 85). This forms a sealed cavity in the translocation channel in agreement with the AMP-PNP·BtuCD-F x-ray structure. When vitamin B12 and AMP-PNP are simultaneously present, the extent of complex formation is reduced, but the short 82–82 interspin distance detected indicates that the substrate does not affect the closed conformation of this gate. The existence of the BtuCD-F complex under these conditions is verified with spectroscopically orthogonal nitroxide and Gd(III)-based labels. The cytoplasmic gate II remains closed also in the vanadate-trapped state, but it reopens in the ADP-bound state of the complex. Therefore, we suggest that the substrate likely trapped in ATP·BtuCD-F can be released after ATP hydrolysis but before the occluded ADP-bound conformation is reached. PMID:24362024

  19. Double electron-electron resonance probes Ca²⁺-induced conformational changes and dimerization of recoverin.

    PubMed

    Myers, William K; Xu, Xianzhong; Li, Congmin; Lagerstedt, Jens O; Budamagunta, Madhu S; Voss, John C; Britt, R David; Ames, James B

    2013-08-27

    Recoverin, a member of the neuronal calcium sensor (NCS) branch of the calmodulin superfamily, is expressed in retinal photoreceptor cells and serves as a calcium sensor in vision. Ca²⁺-induced conformational changes in recoverin cause extrusion of its covalently attached myristate (termed Ca²⁺-myristoyl switch) that promotes translocation of recoverin to disk membranes during phototransduction in retinal rod cells. Here we report double electron-electron resonance (DEER) experiments on recoverin that probe Ca²⁺-induced changes in distance as measured by the dipolar coupling between spin-labels strategically positioned at engineered cysteine residues on the protein surface. The DEER distance between nitroxide spin-labels attached at C39 and N120C is 2.5 ± 0.1 nm for Ca²⁺-free recoverin and 3.7 ± 0.1 nm for Ca²⁺-bound recoverin. An additional DEER distance (5-6 nm) observed for Ca²⁺-bound recoverin may represent an intermolecular distance between C39 and N120. ¹⁵N NMR relaxation analysis and CW-EPR experiments both confirm that Ca²⁺-bound recoverin forms a dimer at protein concentrations above 100 μM, whereas Ca²⁺-free recoverin is monomeric. We propose that Ca²⁺-induced dimerization of recoverin at the disk membrane surface may play a role in regulating Ca²⁺-dependent phosphorylation of dimeric rhodopsin. The DEER approach will be useful for elucidating dimeric structures of NCS proteins in general for which Ca²⁺-induced dimerization is functionally important but not well understood. PMID:23906368

  20. Potential energy curves via double electron-attachment calculations: Dissociation of alkali metal dimers

    NASA Astrophysics Data System (ADS)

    Musiał, Monika; Kowalska-Szojda, Katarzyna; Lyakh, Dmitry I.; Bartlett, Rodney J.

    2013-05-01

    The recently developed method [M. Musiał, J. Chem. Phys. 136, 134111 (2012), 10.1063/1.3700438] to study double electron attached states has been applied to the description of the ground and excited state potential energy curves of the alkali metal dimers. The method is based on the multireference coupled cluster scheme formulated within the Fock space formalism for the (2,0) sector. Due to the use of the efficient intermediate Hamiltonian formulation, the approach is free from the intruder states problem. The description of the neutral alkali metal dimers is accomplished via attaching two electrons to the corresponding doubly ionized system. This way is particularly advantageous when a closed shell molecule dissociates into open shell subunits while its doubly positive cation generates the closed shell fragments. In the current work, we generate the potential energy curves for the ground and multiple excited states of the Li2 and Na2 molecules. In all cases the potential energy curves are smooth for the entire range of interatomic distances (from the equilibrium point to the dissociation limit). Based on the calculated potential energy curves, we are able to compute spectroscopic parameters of the systems studied.

  1. Pressure-Induced Structural and Electronic Transition in Sr2ZnWO6 Double Perovskite.

    PubMed

    Li, Nana; Manoun, Bouchaib; Tang, Lingyun; Ke, Feng; Liu, Fengliang; Dong, Haini; Lazor, Peter; Yang, Wenge

    2016-07-01

    High-pressure structural and electrical properties of Sr2ZnWO6 double perovskite were investigated using in situ angle-dispersive synchrotron X-ray diffraction (XRD), Raman, and alternating current (AC) impedance spectroscopy. A structural transition from monoclinic (P21/n) to triclinic (P1̅) phase around 9 GPa was observed due to the pressure-induced distortion of (W, Zn)O6 octahedron. In situ high-pressure Raman spectroscopy showed the increasing interaction among O-W-O in WO6 octahedron with pressure and a transition pressure consistent with the XRD results. From the AC impedance spectroscopy measurements, the resistivity increased steeply by ∼1 order of magnitude around 11 GPa, indicating an electronic transition accompanying the symmetry change. The increase in the interaction among O-W-O enhances the attraction of O(2-) electrons toward W(6+), thus increasing the covalence, which in turn lowers the charge transfer energy between O(2-) and W(6+) and induces the resistivity increase under high pressure. PMID:27308777

  2. Synthesis of Graphene/diamond Double-Layered Structure for Improving Electron Field Emission Properties

    NASA Astrophysics Data System (ADS)

    Qiao, Yu; Qi, Ting; Liu, Jie; He, Zhiyong; Yu, Shengwang; Shen, Yanyan; Hei, Hongjun

    2016-02-01

    Ultrananocrystalline diamond (UNCD) films on silicon were prepared by microwave plasma chemical vapor deposition (MPCVD) method using argon-rich CH4/H2/Ar plasmas. The graphene sheets synthesized by chemical vapor deposition (CVD) were successfully transferred on to the UNCD surface to fabricate electron field emission (EFE) property-enhanced graphene/UNCD films. The surface morphology, structure and composition of the graphene/UNCD double-layered structures were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), Raman spectroscopy and grazing incidence X-ray diffraction (GXRD). GXRD clearly shows the characteristic diffraction peaks of both diamond and graphene. The Raman spectrum shows the characteristic band of diamond at 1332cm‑1 and D, G and 2D bands of graphene at 1360, 1550 and 2610cm‑1, respectively. The EFE behavior of the composite films can be turned on at E0=2.2V/μm, attaining a current density of 0.065mA/cm2 at an applied field of 7.3V/μm.

  3. Transport and Charge Manipulation in a Single Electron Silicon Double Quantum Dot

    NASA Astrophysics Data System (ADS)

    Wang, K.; Payette, C.; Dovzhenko, Y.; Petta, J. R.

    2013-03-01

    Silicon is one of the most promising candidates for ultra-coherent qubits due to its relatively early position in periodical table and the absence of nuclear spin in its naturally abundant isotope. Here we demonstrate a reliable recipe that enables us to reproducibly fabricate an accumulation mode few electron double quantum dot (DQD). We demonstrate tunable interdot tunnel coupling at single electron occupancy in the device. The charge state of the qubit is monitored by measuring the amplitude of the radio frequency signal that is reflected from a resonant circuit coupled to a charge sensor. By applying microwave radiation to the depletion gates, we probe the energy level structure of the DQD using photon assisted tunneling (PAT). We apply bursts of microwave radiation and monitor the dependence of the PAT peak height on the burst period to extract the charge relaxation time, T1. By experimentally tuning the charge qubit Hamiltonian, we measure the tunnel coupling and detuning dependence of T1. Supported by the United States Department of Defense. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressly or implied, of the U.S. Government.

  4. Hysteresis in the quantum Hall regimes in electron double quantum well structures

    NASA Astrophysics Data System (ADS)

    Pan, W.; Reno, J. L.; Simmons, J. A.

    2005-04-01

    We present here experimental results on magnetotransport coefficients in electron double quantum well (DQW) structures. Consistent with previous studies, transport hysteresis is is observed in the electron DQWs. Furthermore, in our gated DQW samples, by varying the top layer Landau level filling (νtop) while maintaining a relatively constant filling factor in the bottom layer (νbot) , we are able to explain the sign of Rxx(up)-Rxx(down) , where Rxx(up) is the magnetoresistance when the gate voltage Vg is swept up and Rxx(down) when Vg is swept down. Interestingly, at small magnetic fields hysteresis is generally stronger when the top quantum well is in the even integer quantum Hall effect (IQHE) regime (e.g., νtop=2 ) than in the odd IQHE regime (e.g, νtop=1 ). While at higher B fields, the hysteresis at νtop=1 becomes the strongest. The switching occurs around the B field at νbot=3 .

  5. The recent and prospective developments of cooled IR FPAs for double application at Electron NRI

    NASA Astrophysics Data System (ADS)

    Arutunov, V. A.; Vasilyev, I. S.; Ivanov, V. G.; Prokofyev, A. E.

    2003-09-01

    The recent and prospective developments of monolithic silicon IR-Schottky-barrier staring focal plane arrays (IR SB FPAs), photodetector assembly, and digital thermal imaging cameras (TICs) at Electron National Research Institute (Electron NRI) are considered. Basic parameters for IR SB FPAs with 256x256 and 512x512 pixels, and TICs based on these arrays are presented. The problems emerged while proceeding from the developments of IR SB FPAs for the wavelength range from 3 μm to 5 μm to the developments of those ones for xLWIR range are indicated (an abrupt increase in the level of background architecture). Possibility for further improvement in basic parameters of IR SB FPAs are discussed (a decrease in threshold signal power down to 0.5-1.0"1013 W/element with an increase in quantum efficiency, a decrease in output noise and proceeding to Schottky barriers of degenerated semiconductor/silicon heterojunction, and implementation of these array parameters in photodetector assembly with improved thermal background shielding taking into consideration an optical structure of TIC for concrete application). It is concluded that relative simplicity of the technology and expected low cost of monolithic silicon IR SB FPAs with basic parameters compared with hybrid IR FPAs for the wavelength ranges from 3 μm to 5 μm and from 8 μm to 12 μm maintain large monolithic IR SB FPAs as a basis for developments of double application digital TICs in the Russian Federation.

  6. Double proton transfer behavior and one-electron oxidation effect in double H-bonded glycinamide-formic acid complex.

    PubMed

    Li, Ping; Bu, Yuxiang

    2004-11-22

    The behavior of double proton transfer occurring in a representative glycinamide-formic acid complex has been investigated at the B3LYP/6-311 + + G( * *) level of theory. Thermodynamic and, especially, kinetic parameters, such as tautomeric energy, equilibrium constant, and barrier heights have been discussed, respectively. The relevant quantities involved in the double proton transfer process, such as geometrical changes, interaction energies, and intrinsic reaction coordinate calculations have also been studied. Computational results show that the participation of a formic acid molecule favors the proceeding of the proton transfer for glycinamide compared with that without mediate-assisted case. The double proton transfer process proceeds with a concerted mechanism rather than a stepwise one since no ion-pair complexes have been located during the proton transfer process. The calculated barrier heights are 11.48 and 0.85 kcal/mol for the forward and reverse directions, respectively. However, both of them have been reduced by 2.95 and 2.61 kcal/mol to 8.53 and -1.76 kcal/mol if further inclusion of zero-point vibrational energy corrections, where the negative barrier height implies that the reverse reaction should proceed with barrierless spontaneously, analogous to that occurring between glycinamide and formamide. Furthermore, solvent effects on the thermodynamic and kinetic processes have also been predicted qualitatively employing the isodensity surface polarized continuum model within the framework of the self-consistent reaction field theory. Additionally, the oxidation process for the double H-bonded glycinamide-formic acid complex has also been investigated. Contrary to that neutral form possessing a pair of two parallel intermolecular H bonds, only a single H bond with a comparable strength has been found in its ionized form. The vertical and adiabatic ionization potentials for the neutral complex have been determined to be about 9.40 and 8.69 e

  7. Ion-Acoustic Double-Layers in Plasmas with Nonthermal Electrons

    NASA Astrophysics Data System (ADS)

    Rios, L. A.; Galvão, R. M. O.

    2014-12-01

    A double layer (DL) consists of a positive/negative Debye sheath, connecting two quasineutral regions of a plasma. These nonlinear structures can be found in a variety of plasmas, from discharge tubes to space plasmas. It has applications to plasma processing and space propulsion, and its concept is also important for areas such as applied geophysics. In the present work we investigate the ion-acoustic double-layers (IADLs). It is believed that these structures are responsible for the acceleration of auroral electrons, for example. The plasma distributions near a DL are usually non-Maxwellian and can be modeled via a κ distribution function. In its reduced form, the standard κ distribution is equivalent to the distribution function obtained from the maximization of the Tsallis entropy, the q distribution. The parameters κ and q measure the deviation from the Maxwellian equilibrium ("nonthermality"), with -κ=1/(1-q) (in the limit κ → ∞ (q → 1) the Maxwellian distribution is recovered). The existence of obliquely propagating IADLs in magnetized two-electron plasmas is investigated, with the hot electron population modeled via a κ distribution function [1]. Our analysis shows that only subsonic and rarefactive DLs exist for the entire range of parameters investigated. The small amplitude DLs exist only for τ=Th/Tc greater than a critical value, which grows as κ decreases. We also observe that these structures exist only for large values of δ=Nh0/N0, but never for δ=1. In our model, which assumes a quasineutral condition, the Mach number M grows as θ decreases (θ is the angle between the directions of the external magnetic field and wave propagation). However, M as well as the DL amplitude are reduced as a consequence of nonthermality. The relation of the quasineutral condition and the functional form of the distribution function with the nonexistence of IADLs has also been analyzed and some interesting results have been obtained. A more detailed

  8. Scaling of cross sections for K-electron capture by high-energy protons and alpha-particles from the multielectron atoms

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1976-01-01

    Electron capture by protons from H, He, and the K-shell of Ar, and alpha particles from He are considered. It is shown that when a certain function of the experimental cross sections is plotted versus the inverse of the collision energy, at high energies the function falls on a straight line. At lower energies the function concaves up or down, depending on the charge of the projectile, the effective charge and the ionization potential of the electron that is being captured. The plot can be used to predict cross sections where experimental data are not available, and as a guide in future experiments. High energy scaling formulas for K-electron capture by low-charge projectiles are given.

  9. Capturing peripersonal spatial neglect: an electronic method to quantify visuospatial processes.

    PubMed

    Vaes, Nathalie; Lafosse, Christophe; Nys, Gudrun; Schevernels, Hanne; Dereymaeker, Lutgart; Oostra, Kristine; Hemelsoet, Dimitri; Vingerhoets, Guy

    2015-03-01

    Computerized as well as paper-and-pencil tasks are applied in mapping visuospatial neglect in experimental research and clinical practice. This article presents a new kind of computer-based assessment method, using an electronic pen display and user-friendly software. The approach is tailored to specific spatial processes and highlights the usefulness of a pen display in neglect patients. The advantages of the introduced method are illustrated by a recently designed battery of classic, as well as new, types of tests. The development of the appropriate stimuli and the assorted scoring systems is addressed, as well as the resulting types of task implementation and data generation. The diagnostic value of the different visuospatial neglect tests is demonstrated by comparative analyses between a neglect group and a control group. Among the benefits of the proposed assessment method are (1) the opportunity to perform standardized repeated measurements to quantify recovery, (2) online performance monitoring, (3) flexible employment, (4) the collection of exact data over a short period, and (5) the easy availability of more refined quantitative as well as interesting qualitative information, especially as compared to classic or paper-and-pencil tasks. To indicate that this method also lends itself well to measures for treatment procedures, an illustration is given with respect to specific measurements during prism adaptation. The tasks of the Visuospatial Neglect Test Battery and the prism adaptation measures are illustrated by a case study. The outlined applications are discussed with respect to experimental as well as clinical purposes. PMID:24567147

  10. Simplifying electronic data capture in clinical trials: workflow embedded image and biosignal file integration and analysis via web services.

    PubMed

    Haak, Daniel; Samsel, Christian; Gehlen, Johan; Jonas, Stephan; Deserno, Thomas M

    2014-10-01

    To improve data quality and save cost, clinical trials are nowadays performed using electronic data capture systems (EDCS) providing electronic case report forms (eCRF) instead of paper-based CRFs. However, such EDCS are insufficiently integrated into the medical workflow and lack in interfacing with other study-related systems. In addition, most EDCS are unable to handle image and biosignal data, although electrocardiography (EGC, as example for one-dimensional (1D) data), ultrasound (2D data), or magnetic resonance imaging (3D data) have been established as surrogate endpoints in clinical trials. In this paper, an integrated workflow based on OpenClinica, one of the world's largest EDCS, is presented. Our approach consists of three components for (i) sharing of study metadata, (ii) integration of large volume data into eCRFs, and (iii) automatic image and biosignal analysis. In all components, metadata is transferred between systems using web services and JavaScript, and binary large objects (BLOBs) are sent via the secure file transfer protocol and hypertext transfer protocol. We applied the close-looped workflow in a multicenter study, where long term (7 days/24 h) Holter ECG monitoring is acquired on subjects with diabetes. Study metadata is automatically transferred into OpenClinica, the 4 GB BLOBs are seamlessly integrated into the eCRF, automatically processed, and the results of signal analysis are written back into the eCRF immediately. PMID:24802371

  11. An experiment to verify that the weak interactions satisfy the strong equivalence principle. [electron capture and gravitational potential

    NASA Technical Reports Server (NTRS)

    Eby, P. B.

    1978-01-01

    The construction of a clock based on the beta decay process is proposed to test for any violations by the weak interaction of the strong equivalence principle bu determining whether the weak interaction coupling constant beta is spatially constant or whether it is a function of gravitational potential (U). The clock can be constructed by simply counting the beta disintegrations of some suitable source. The total number of counts are to be taken a measure of elapsed time. The accuracy of the clock is limited by the statistical fluctuations in the number of counts, N, which is equal to the square root of N. Increasing N gives a corresponding increase in accuracy. A source based on the electron capture process can be used so as to avoid low energy electron discrimination problems. Solid state and gaseous detectors are being considered. While the accuracy of this type of beta decay clock is much less than clocks based on the electromagnetic interaction, there is a corresponding lack of knowledge of the behavior of beta as a function of gravitational potential. No predictions from nonmetric theories as to variations in beta are available as yet, but they may occur at the U/sg C level.

  12. Time Modulation of the K-Shell Electron Capture Decay Rates of H-like Heavy Ions at GSI Experiments

    SciTech Connect

    Ivanov, A. N.; Kienle, P.

    2009-08-07

    According to experimental data at GSI, the rates of the number of daughter ions, produced by the nuclear K shell electron capture decays of the H-like heavy ions with one electron in the K shell, such as {sup 140}Pr{sup 58+}, {sup 142}Pm{sup 60+}, and {sup 122}I{sup 52+}, are modulated in time with periods T{sub EC} of the order of a few seconds, obeying an A scaling T{sub EC}=A/20 s, where A is the mass number of the mother nuclei, and with amplitudes a{sub d}{sup EC}approx0.21. We show that these data can be explained in terms of the interference of two massive neutrino mass eigenstates. The appearance of the interference term is due to overlap of massive neutrino mass eigenstate energies and of the wave functions of the daughter ions in two-body decay channels, caused by the energy and momentum uncertainties introduced by time differential detection of the daughter ions in GSI experiments.

  13. Coherent manipulation of a single magnetic atom using polarized single electron transport in a double quantum dot

    NASA Astrophysics Data System (ADS)

    Lai, Wenxi; Yang, Wen

    2015-10-01

    We consider theoretically a magnetic impurity spin driven by polarized electrons tunneling through a double-quantum-dot system. The spin-blockade effect and spin conservation in the system make the magnetic impurity sufficiently interact with each transferring electron. As a result, a single collected electron carries information about spin change of the magnetic impurity. The scheme may develop all-electrical manipulation of magnetic atoms by means of single electrons, which is significant for the implementation of scalable logical gates in information processing systems.

  14. Medical Registry Data Collection Efficiency: A Crossover Study Comparing Web-Based Electronic Data Capture and a Standard Spreadsheet

    PubMed Central

    Staziaki, Pedro Vinícius; Kim, Phillip; Vadvala, Harshna V

    2016-01-01

    Background Electronic medical records and electronic data capture (EDC) have changed data collection in clinical and translational research. However, spreadsheet programs, such as Microsoft Excel, are still used as data repository to record and organize patient data for research. Objective The objective of this study is to assess the efficiency of EDC as against a standard spreadsheet in regards to time to collect data and data accuracy, measured in number of errors after adjudication. Methods This was a crossover study comparing the time to collect data in minutes between EDC and a spreadsheet. The EDC tool used was Research Electronic Data Capture (REDCap), whereas the spreadsheet was Microsoft Excel. The data collected was part of a registry of patients who underwent coronary computed tomography angiography in the emergency setting. Two data collectors with the same experience went over the same patients and collected relevant data on a case report form identical to the one used in our Emergency Department (ED) registry. Data collection tool was switched after the patient that represented half the cohort. For this, the patient cohort was exactly 30 days of our ED coronary Computed Tomography Angiography registry and the point of crossover was determined beforehand to be 15 days. We measured the number of patients admitted, and time to collect data. Accuracy was defined as absence of blank fields and errors, and was assessed by comparing data between data collectors and counting every time the data differed. Statistical analysis was made using paired t -test. Results The study included 61 patients (122 observations) and 55 variables. The crossover occurred after the 30th patient. Mean time to collect data using EDC in minutes was 6.2±2.3, whereas using Excel was 8.0±2.0 (P <.001), a difference of 1.8 minutes between both means (22%). The cohort was evenly distributed with 3 admissions in the first half of the crossover and 4 in the second half. We saw 2 (<0

  15. Combined infrared multiphoton dissociation and electron capture dissociation with a hollow electron beam in Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Tsybin, Youri O; Witt, Matthias; Baykut, Gökhan; Kjeldsen, Frank; Håkansson, Per

    2003-01-01

    An electron injection system based on an indirectly heated ring-shaped dispenser cathode has been developed and installed in a 7 Tesla Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. This new hardware design allows high-rate electron capture dissociation (ECD) to be carried out by a hollow electron beam coaxial with the ion cyclotron resonance (ICR) trap. Infrared multiphoton dissociation (IRMPD) can also be performed with an on-axis IR-laser beam passing through a hole at the centre of the dispenser cathode. Electron and photon irradiation times of the order of 100 ms are required for efficient ECD and IRMPD, respectively. As ECD and IRMPD generate fragments of different types (mostly c, z and b, y, respectively), complementary structural information that improves the characterization of peptides and proteins by FTICR mass spectrometry can be obtained. The developed technique enables the consecutive or simultaneous use of the ECD and IRMPD methods within a single FTICR experimental sequence and on the same ensemble of trapped ions in multistage tandem (MS/MS/MS or MS(n)) mass spectrometry. Flexible changing between ECD and IRMPD should present advantages for the analysis of protein digests separated by liquid chromatography prior to FTICRMS. Furthermore, ion activation by either electron or laser irradiation prior to, as well as after, dissociation by IRMPD or ECD increases the efficiency of ion fragmentation, including the w-type fragment ion formation, and improves sequencing of peptides with multiple disulfide bridges. The developed instrumental configuration is essential for combined ECD and IRMPD on FTICR mass spectrometers with limited access into the ICR trap. PMID:12872281

  16. Linear augmented cylindrical wave method for calculating the electronic structure of double-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    D'Yachkov, P. N.; Makaev, D. V.

    2006-10-01

    Electronic structure of double-wall carbon nanotubes (DWNTs) consisting of two concentric graphene cylinders with extremely strong covalent bonding of atoms within the individual graphitic sheets, but very weak van der Waals type interaction between them is calculated in the terms of the linear augmented cylindrical wave (LACW) method. A one-electron potential is used and the approximations are made in the sense of muffin-tin (MT) potentials and local density functional theory only. The atoms of DWNT are considered to be enclosed between cylinder-shaped potential barriers. In this approach, the electronic spectrum of the DWNTs is governed by the free movement of electron in the interatomic space of two cylindrical layers, by electron scattering on the MT spheres, and by electron tunneling between the layers. We have calculated the complete band structures and densities of states in the Fermi level region of the purely semiconducting zigzag DWNTs (n,0)@(n',0) ( 10⩽n⩽23 and 19⩽n'⩽32 ) with interlayer distance 3.2Å⩽Δd⩽3.7Å . Analogously data are obtained for metallic armchair (n,n)@(n',n') nanotubes ( n=5 or 4 and n'=10 or 9). According to the LACW calculations, the interwall coupling results in a distinctly stronger perturbation of the band structure of inner tube as compared to that of the outer one. In the case of semiconducting DWNTs, the minimum gap E11 between the singularities of the conduction and valence bands of the shell tubules decreases from 0.15to0.22eV or increases from 0.7to0.15eV , if dividing n' by three leaves a remainder of 1 or 2, respectively. In both cases, the ΔE11 shifts of the gap do not decay, but slightly oscillate as one goes to the tubules with larger diameters d . For inner tubules, the ΔE11 shift depends strongly on the d . For nmod3=2 series with 10⩽n⩽16 , the shifts ΔE11 are positive, the maximum values of ΔE11 being equal to 0.39 and 0.32eV , respectively. As one goes to the inner tubules with larger diameters

  17. The electronic states of a double carbon vacancy defect in pyrene: a model study for graphene.

    PubMed

    Machado, Francisco B C; Aquino, Adélia J A; Lischka, Hans

    2015-05-21

    The electronic states occurring in a double vacancy defect for graphene nanoribbons have been calculated in detail based on a pyrene model. Extended ab initio calculations using the MR configuration interaction (MRCI) method have been performed to describe in a balanced way the manifold of electronic states derived from the dangling bonds created by initial removal of two neighboring carbon atoms from the graphene network. In total, this study took into account the characterization of 16 electronic states (eight singlets and eight triplets) considering unrelaxed and relaxed defect structures. The ground state was found to be of (1)Ag character with around 50% closed shell character. The geometry optimization process leads to the formation of two five-membered rings in a pentagon-octagon-pentagon (5-8-5) structure. The closed shell character increases thereby to ∼70%; the analysis of unpaired density shows only small contributions confirming the chemical stability of that entity. For the unrelaxed structure the first five excited states ((3)B3g, (3)B2u, (3)B1u, (3)Au and (1)Au) are separated from the ground state by less than 2.5 eV. For comparison, unrestricted density functional theory (DFT) calculations using several types of functionals have been performed within different symmetry subspaces defined by the open shell orbitals. Comparison with the MRCI results gave good agreement in terms of finding the (1)Ag state as a ground state and in assigning the lowest excited states. Linear interpolation curves between the unrelaxed and relaxed defect structures also showed good agreement between the two classes of methods opening up the possibilities of using extended nanoflakes for multistate investigations at the DFT level. PMID:25905682

  18. Kuang's Semi-Classical Formalism for Electron Capture Cross-Sections in Ion-Ion Collisions at Approximately to MeV/amu: Application to ENA Modeling

    NASA Technical Reports Server (NTRS)

    Barghouty, A. F.

    2012-01-01

    Recent discovery by STEREO A/B of energetic neutral hydrogen is spurring an interest and need for reliable estimates of electron capture cross sections at few MeVs per nucleon as well as for multi-electron ions. Required accuracy in such estimates necessitates detailed and involved quantum-mechanical calculations or expensive numerical simulations. For ENA modeling and similar purposes, a semi-classical approach offers a middle-ground approach. Kuang's semiclassical formalism to calculate electron-capture cross sections for single and multi-electron ions is an elegant and efficient method, but has so far been applied to limited and specific laboratory measurements and at somewhat lower energies. Our goals are to test and extend Kuang s method to all ion-atom and ion-ion collisions relevant to ENA modeling, including multi-electron ions and for K-shell to K-shell transitions.

  19. Ion-acoustic double layers in a five component cometary plasma with kappa described electrons and ions

    NASA Astrophysics Data System (ADS)

    Michael, Manesh; Venugopal, C.; Sreekala, G.; Willington, Neethu Theresa; Sebastian, Sijo

    2016-07-01

    We investigate the propagation characteristics of Ion-acoustic solitons and double layers in a five component cometary plasma consisting of positively and negatively charged oxygen ions, kappa described hydrogen ions, hot solar electrons, and slightly colder cometary electrons. The KdV and modified KdV equations are derived for the system and its solution is plotted for different kappa values and negatively charged oxygen ion densities. It is found that the strength of double layer increases with increasing spectral indices. It, however, decreases with increasing negatively charged oxygen ion densities. The parameter for the transition from compressive to rarefactive soliton is also specified. The presence of negatively charged oxygen ions can significantly affect the nonlinearity coefficients (both quadratic and cubic) of a double layer.

  20. Theoretical state-selective and total cross sections for electron capture from helium atoms by fully stripped ions

    NASA Astrophysics Data System (ADS)

    Mančev, I.; Milojević, N.; Belkić, Dž.

    2015-03-01

    The four-body boundary-corrected first Born (CB1-4B) approximation is used to compute cross sections for single electron capture from helium targets by fully stripped ions. The projectile ions are H+, He2+, Li3+, Be4+, B5+, C6+, N7+, O8+, and F9+. An extensive list of theoretical state-to-state cross sections in these collisions at energies ranging from 20 to 10 000 keV/amu is given. This list includes the state-selective cross sections Qnlm for each individual triple of the usual quantum numbers { n , l , m } of the final hydrogen-like states alongside Qnl and Qn for the pertinent sub-shells and shells where the respective summations over m and { l , m } have been carried out. The maximal value of the principal quantum number n was chosen to vary from 4 (H+) to 10 (F9+) so as to satisfy the condition n ≥ZP, where ZP is the nuclear charge of the projectile. Usually, the largest cross sections stem from those values of n that match the projectile charge (n =ZP) . The total cross sections for capture summed over all the quantum numbers { n , l , m } are also tabulated. The overall goal of this study is to fill in lacunae in the existing databases of charge exchange cross sections that are needed in several inter-disciplinary fields. For example, in particle transport physics, which is of utmost importance in such emerging branches as hadron therapy, these cross sections constitute a part of the multifaceted input data for stochastic simulations of energy losses of multiply charged ions in matter, including tissue. Other significant uses of the present data are anticipated in charge exchange diagnostics within thermonuclear research project as well as in applications covering the relevant parts of plasma physics and astrophysics.