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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 {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.

  4. 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.

  5. 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.

  6. 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.

  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. 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.

  16. 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).

  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. 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+}.

  14. 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%).

  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 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

  17. 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

  18. 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.

  19. 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.

  20. 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.

  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. 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

  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. 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.

  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. 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

  13. 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.

  14. 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.

  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. 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

  6. 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

  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 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.

  18. 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.

  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. 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.

  5. 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...

  6. 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.

  7. 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.

  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. 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.

  16. 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.

  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

    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.

  5. 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.

  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. 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

  14. 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.

  15. 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

  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. 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.

  4. 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

  5. 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.

  6. 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.

  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. 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.

  14. 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

  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 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

  16. 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

  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. 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.

  1. 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.

  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. 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

  6. 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.

  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. 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

  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. 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

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  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. 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.

  5. 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

  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. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  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. 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

  3. 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.

  4. 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

  5. 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.

  6. 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

  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. 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