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

Science.gov (United States)

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

2003-03-07

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

Electron capture detector based on a non-radioactive electron source: operating parameters vs. analytical performance

Directory of Open Access Journals (Sweden)

E. Bunert

2017-12-01

Full Text Available Gas chromatographs with electron capture detectors are widely used for the analysis of electron affine substances such as pesticides or chlorofluorocarbons. With detection limits in the low pptv range, electron capture detectors are the most sensitive detectors available for such compounds. Based on their operating principle, they require free electrons at atmospheric pressure, which are usually generated by a β− decay. However, the use of radioactive materials leads to regulatory restrictions regarding purchase, operation, and disposal. Here, we present a novel electron capture detector based on a non-radioactive electron source that shows similar detection limits compared to radioactive detectors but that is not subject to these limitations and offers further advantages such as adjustable electron densities and energies. In this work we show first experimental results using 1,1,2-trichloroethane and sevoflurane, and investigate the effect of several operating parameters on the analytical performance of this new non-radioactive electron capture detector (ECD.

Electron capture by highly charged ions from surfaces and gases

Energy Technology Data Exchange (ETDEWEB)

Allen, F.

2008-01-11

In this study highly charged ions produced in Electron Beam Ion Traps are used to investigate electron capture from surfaces and gases. The experiments with gas targets focus on spectroscopic measurements of the K-shell x-rays emitted at the end of radiative cascades following electron capture into Rydberg states of Ar{sup 17+} and Ar{sup 18+} ions as a function of collision energy. The ions are extracted from an Electron Beam Ion Trap at an energy of 2 keVu{sup -1}, charge-selected and then decelerated down to 5 eVu{sup -1} for interaction with an argon gas target. For decreasing collision energies a shift to electron capture into low orbital angular momentum capture states is observed. Comparative measurements of the K-shell x-ray emission following electron capture by Ar{sup 17+} and Ar{sup 18+} ions from background gas in the trap are made and a discrepancy in the results compared with those from the extraction experiments is found. Possible explanations are discussed. For the investigation of electron capture from surfaces, highly charged ions are extracted from an Electron Beam Ion Trap at energies of 2 to 3 keVu{sup -1}, charge-selected and directed onto targets comprising arrays of nanoscale apertures in silicon nitride membranes. The highly charged ions implemented are Ar{sup 16+} and Xe{sup 44+} and the aperture targets are formed by focused ion beam drilling in combination with ion beam assisted thin film deposition, achieving hole diameters of 50 to 300 nm and aspect ratios of 1:5 to 3:2. After transport through the nanoscale apertures the ions pass through an electrostatic charge state analyzer and are detected. The percentage of electron capture from the aperture walls is found to be much lower than model predictions and the results are discussed in terms of a capillary guiding mechanism. (orig.)

Electronic case report forms and electronic data capture within clinical trials and pharmacoepidemiology.

Science.gov (United States)

Rorie, David A; Flynn, Robert W V; Grieve, Kerr; Doney, Alexander; Mackenzie, Isla; MacDonald, Thomas M; Rogers, Amy

2017-09-01

Researchers in clinical and pharmacoepidemiology fields have adopted information technology (IT) and electronic data capture, but these remain underused despite the benefits. This review discusses electronic case report forms and electronic data capture, specifically within pharmacoepidemiology and clinical research. The review used PubMed and the Institute of Electrical and Electronic Engineers library. Search terms used were agreed by the authors and documented. PubMed is medical and health based, whereas Institute of Electrical and Electronic Engineers is technology based. The review focuses on electronic case report forms and electronic data capture, but briefly considers other relevant topics; consent, ethics and security. There were 1126 papers found using the search terms. Manual filtering and reviewing of abstracts further condensed this number to 136 relevant manuscripts. The papers were further categorized: 17 contained study data; 40 observational data; 27 anecdotal data; 47 covering methodology or design of systems; one case study; one literature review; two feasibility studies; and one cost analysis. Electronic case report forms, electronic data capture and IT in general are viewed with enthusiasm and are seen as a cost-effective means of improving research efficiency, educating participants and improving trial recruitment, provided concerns about how data will be protected from misuse can be addressed. Clear operational guidelines and best practises are key for healthcare providers, and researchers adopting IT, and further work is needed on improving integration of new technologies with current systems. A robust method of evaluation for technical innovation is required. © 2017 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.

Single electron capture in N^+ -(Ne, Kr, Xe) collisions

Science.gov (United States)

Reyes, Pedro G.; Castillo, Fermin; Martinez, Horacio

2001-05-01

Total cross sections for single electron capture of N^+ ions impinging on Ne, Kr and Xe were measured in the energy range of 1.5 to 5.0 keV. The electron capture cross sections for all the targets studied are found to be in excellent agreement with previous data in the low-energy range. The present data together with previous measurements give a general shape of the whole curve of single electron capture cross sections for the N^+ - Ne system. For the cases of N^+ - (Kr, Xe) systems, semiempirical calculation using the two-state approximation are in very good agreement with present cross sections data. Research supported by DGAPA IN-100392 and CONACyT 32175-E

Evidence for correlated double-electron capture in slow O6+ + He collisions

International Nuclear Information System (INIS)

Phaneuf, R.A.; Meyer, F.W.; Havener, C.C.; Stolterfoht, N.; Swenson, J.K.; Shafroth, S.M.

1987-01-01

Double electron capture by few-electron multicharged ions during slow collisions with He may result in Auger-decaying product states of the projectile, provided the initial projectile charge exceeds +4. These autoionizing states can be characterized by either (nearly) equivalent electron configurations, in which the two captured electrons occupy essentially the same or adjacent shells, or by non-equivalent configurations, in which one of the electrons is in a Rydberg state. Using the method of zero-degree Auger spectroscopy, the authors have verified population of both types of autoionizing states by double electron capture during slow collisions of O 6+ with He: for these systems, both LMM Auger electrons, attributed to the (nearly) equivalent electron configuration (1s 2 ) 3iota3iota' or (1s 2 )3iota4iota', and L 1 L 23 M-Coster Kronig electrons, attributed to the non-equivalent electron configurations (1s 2 )2pniota, were observed. Comparison of the LMM Auger electron and Coster Kronig electron production cross sections suggests that the correlated double capture process is of comparable importance to the sequential single capture mechanism

Electron capture in asymmetric collisions

International Nuclear Information System (INIS)

Graviele, M.S.; Miraglia, J.E.

1988-01-01

It is calculated the electronic capture of K shell by protons using the on-shell impulsive wave functions, exact and eikonal, in the initial and final channels respectively. Both wave functions are normalized and have the correct asyntotic conditions. A good agreement to the experimental data is found. (A.C.A.S.) [pt

Electron capture to autoionizing states of multiply charged ions

International Nuclear Information System (INIS)

Mack, E.M.

1987-01-01

The present thesis investigates electron capture reactions resulting from slow collisions (V q+ ) and neutral gas targets (B). The energy spectra of the emitted electrons are measured; detection angle is 50 0 . Mainly, autoionizing double capture resulting from collisions with two-electron targets (He, H 2 ) is studied; then, the emitted electrons stem from doubly excited projectile states. The projectiles used are bare C 6+ , the H-like and He-like ions of C, N and O, He-like Ne 8+ and Ne-like Ar 8+ . Excited metastable projectiles used are C 5+ (2s), He-like projectiles A q+ (1s2s 3 S) and Ar 8+ (...2p 5 3s). Comparison is made with the predictions of a recently proposed extended classical barrier model, that was developed in connection with the work. This model assumes sequential capture of the electrons ('two-step' process); it predicts the realized binding enegies of the captured electrons - which may be directly determined from the autoionization spectra using only the projectile charge, the ionization potentials of the target and the collision velocity as parameters. No adjustable parameter enters into the calculations. The term energies and decay modes of the highly excited product ions themselves are studied. Generally, the autoionizing decay of these states is found to proceed preferentially to the directly adjacent lower singly excited state. Experimental evidence is presented, that triply excited states decay by successive emission of two electrons, whenever this is energetically possible. Finally, the L-MM decay in few-electron systems is considered. 314 refs.; 96 figs.; 29 tabs

Alpha-particle and electron capture decay of 209Po

International Nuclear Information System (INIS)

Schima, F.J.; Colle, R.

1996-01-01

Gamma-ray and Kα X-ray emissions have been measured from a very pure 209 Po source containing less than 0.13% 208 Po activity and no detectable 210 Po (≤2 x 10 -4 %). The alpha-particle emission rate for this source has previously been determined. Data are presented that confirm alpha decay to the 205 Pb excited level at 262.8 keV, with an alpha-particle emission probability (±standard uncertainty) of 0.00559±0.00008. The ratio of K-shell electron capture to total electron capture for the second forbidden unique electron capture decay to the 896.6 keV level in 209 Bi was determined to be 0.594±0.018. The electron capture decay fraction was found to be 0.00454±0.00007, while the probabilities per decay for the 896.6, 262.8, and 260.5 keV gamma rays and the Bi Kα and Pb Kα X-rays were measured as 0.00445±0.00007, 0.00085±0.00002, 0.00254±0.00003, 0.00202±0.00005, and 0.00136±0.00005, respectively. (orig.)

Distinguishing of Ile/Leu amino acid residues in the PP3 protein by (hot) electron capture dissociation in Fourier transform ion cyclotron resonance mass spectrometry

DEFF Research Database (Denmark)

Kjeldsen, Frank; Haselmann, Kim F; Sørensen, Esben Skipper

2003-01-01

In hot electron capture dissociation (HECD), multiply protonated polypeptides fragment upon capturing approximately 11-eV electrons. The excess of energy upon the primary c, z* cleavage induces secondary fragmentation in z* fragments. The resultant w ions allow one to distinguish between the isom...

Maximum entropy theory of recoil charge distributions in electron-capture collisions

International Nuclear Information System (INIS)

Aberg, T.; Blomberg, A.; Tulkki, J.; Goscinski, O.

1984-01-01

A generalized Fermi-Dirac distribution is derived and applied to charge-state distributions in single collisions between multiply charged ions and rare-gas atoms. It relates multiple electron loss in single-electron capture to multiple ionization in multiphoton absorption and discloses inner-shell vacancy formation in double- and triple-electron capture

Supernovae and nuclear structure: Electron capture and the nuclear incompressibility

International Nuclear Information System (INIS)

Cooperstein, J.

1985-01-01

The author considers the effects of electron capture and the high density equation of state on supernovae. Electron captures on nuclei with 60 s it is helpful for supernovae to have a soft equation of state. Present knowledge of the nuclear matter parameters is considered and implications for supernovae are drawn. (orig.)

Correlated double electron capture in slow, highly charged ion-atom collisions

International Nuclear Information System (INIS)

Stolterfoht, N.; Havener, C.C.; Phaneuf, R.A.; Swenson, J.K.; Shafroth, S.M.; Meyer, F.W.

1986-01-01

Recent measurements of autoionization electrons produced in slow, highly charged ion-atom collisions are reviewed. Mechanisms for double electron capture into equivalent and nonequivalent configurations are analyzed by comparing the probabilities for the creation of L 1 L 23 X Coster Kronig electrons and L-Auger electrons. It is shown that the production of the Coster-Kronig electrons is due to electron correlation effects whose analysis leads beyond the independent-particle model. The importance of correlation effects on different capture mechanisms is discussed. 28 refs., 6 figs

Calculations on Electron Capture in Low Energy Ion-Molecule Collisions

Energy Technology Data Exchange (ETDEWEB)

Stancil, P.C. [Oak Ridge National Lab., TN (United States); Zygelman, B. [W.M. Keck Lab. for Computational Physics, Univ. of Nevada, Las Vegas, NV (United States); Kirby, K. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)

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

Correlated double electron capture in slow, highly charged ion-atom collisions

Energy Technology Data Exchange (ETDEWEB)

Stolterfoht, N.; Havener, C.C.; Phaneuf, R.A.; Swenson, J.K.; Shafroth, S.M.; Meyer, F.W.

1986-01-01

Recent measurements of autoionization electrons produced in slow, highly charged ion-atom collisions are reviewed. Mechanisms for double electron capture into equivalent and nonequivalent configurations are analyzed by comparing the probabilities for the creation of L/sub 1/L/sub 23/X Coster Kronig electrons and L-Auger electrons. It is shown that the production of the Coster-Kronig electrons is due to electron correlation effects whose analysis leads beyond the independent-particle model. The importance of correlation effects on different capture mechanisms is discussed. 28 refs., 6 figs.

Genetic effects of decay by electron capture of radionuclides in yeasts cell

International Nuclear Information System (INIS)

Gracheva, L.M.; Korolev, V.G.

1984-01-01

Regularities of genetic effect on the yeast cell Saccharomyces cerevisiae, incorporated radionuclides decaying according to the scheme of k-capture- 7 Be, 54 Mn, 85 Sr are studied. It is known that this type of decay models the ionization of internal electron shells of atoms which is most probable when a cell is affected by external ionizing radiation. It is shown that the decay of radionuclides connecting with a DNA molecule in a cell according to the scheme of D-capture brings about a strong lethal effect. The relative mutagenic efficiency is much lower than that for gamma-radiation and many radionuclides decaying according to the scheme of B-decay. In the mutation spectrum induced by these radionuclides the increase in the number of mutations of the reading frame shift type is observed

Search for neutrinoless double-electron capture of 156Dy

Science.gov (United States)

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.

Experimental studies of electron capture

International Nuclear Information System (INIS)

Pedersen, E.H.

1983-01-01

This thesis discusses the main results of recent experimental studies of electron capture in asymmetric collisions. Most of the results have been published, but the thesis also contains yet unpublished data, or data presented only in unrefereed conference proceedings. The thesis aims at giving a coherent discussion of the understanding of the experimental results, based first on simple qualitative considerations and subsequently on quantitative comparisons with the best theoretical calculations currently available. (Auth.)

Distorted wave calculations for electron loss process induced by bare ion impact on biological targets

International Nuclear Information System (INIS)

Monti, J.M.; Tachino, C.A.; Hanssen, J.; Fojón, O.A.; Galassi, M.E.; Champion, C.; Rivarola, R.D.

2014-01-01

Distorted wave models are employed to investigate the electron loss process induced by bare ions on biological targets. The two main reactions which contribute to this process, namely, the single electron ionization as well as the single electron capture are here studied. In order to further assess the validity of the theoretical descriptions used, the influence of particular mechanisms are studied, like dynamic screening for the case of electron ionization and energy deposition on the target by the impacting projectile for the electron capture one. Results are compared with existing experimental data. - Highlights: ► Distorted wave models are used to investigate ion-molecule collisions. ► Differential and total cross-sections for capture and ionization are evaluated. ► The influence of dynamic screening is determined. ► Capture reaction dominates the mean energy deposited by the projectile on the target

Electron Capture Cross Sections for Stellar Nucleosynthesis

Directory of Open Access Journals (Sweden)

P. G. Giannaka

2015-01-01

Full Text Available In the first stage of this work, we perform detailed calculations for the cross sections of the electron capture on nuclei under laboratory conditions. Towards this aim we exploit the advantages of a refined version of the proton-neutron quasiparticle random-phase approximation (pn-QRPA and carry out state-by-state evaluations of the rates of exclusive processes that lead to any of the accessible transitions within the chosen model space. In the second stage of our present study, we translate the abovementioned e--capture cross sections to the stellar environment ones by inserting the temperature dependence through a Maxwell-Boltzmann distribution describing the stellar electron gas. As a concrete nuclear target we use the 66Zn isotope, which belongs to the iron group nuclei and plays prominent role in stellar nucleosynthesis at core collapse supernovae environment.

Introductory remarks on electron capture by multicharged ions

International Nuclear Information System (INIS)

Crandall, D.H.

1979-01-01

An overview is presented of applications of multicharged-ion electron capture and, through the qualitative assessment of availability of information, the general status of current understanding of such capture. A chart is given on which the various ion collision processes are related to other pertinent fields of physical research notably fusion, astrophysics, the solar corona, and lasers. The production and transport of ions is also noted. The symposium considers collision velocities less than 4 x 10 8 cm/s, where the capture cross sections are largest and where most of the available results are quite recent

ELECTRON-CAPTURE AND β-DECAY RATES FOR sd-SHELL NUCLEI IN STELLAR ENVIRONMENTS RELEVANT TO HIGH-DENSITY O–NE–MG CORES

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Toshio [Department of Physics and Graduate School of Integrated Basic Sciences, College of Humanities and Sciences, Nihon University Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550 (Japan); Toki, Hiroshi [Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047 (Japan); Nomoto, Ken’ichi, E-mail: suzuki@phys.chs.nihon-u.ac.jp [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)

2016-02-01

Electron-capture and β-decay rates for nuclear pairs in the sd-shell are evaluated at high densities and high temperatures relevant to the final evolution of electron-degenerate O–Ne–Mg cores of stars with initial masses of 8–10 M{sub ⊙}. Electron capture induces a rapid contraction of the electron-degenerate O–Ne–Mg core. The outcome of rapid contraction depends on the evolutionary changes in the central density and temperature, which are determined by the competing processes of contraction, cooling, and heating. The fate of the stars is determined by these competitions, whether they end up with electron-capture supernovae or Fe core-collapse supernovae. Since the competing processes are induced by electron capture and β-decay, the accurate weak rates are crucially important. The rates are obtained for pairs with A = 20, 23, 24, 25, and 27 by shell-model calculations in the sd-shell with the USDB Hamiltonian. Effects of Coulomb corrections on the rates are evaluated. The rates for pairs with A = 23 and 25 are important for nuclear Urca processes that determine the cooling rate of the O–Ne–Mg core, while those for pairs with A = 20 and 24 are important for the core contraction and heat generation rates in the core. We provide these nuclear rates at stellar environments in tables with fine enough meshes at various densities and temperatures for studies of astrophysical processes sensitive to the rates. In particular, the accurate rate tables are crucially important for the final fates of not only O–Ne–Mg cores but also a wider range of stars, such as C–O cores of lower-mass stars.

ELECTRON-CAPTURE AND β-DECAY RATES FOR sd-SHELL NUCLEI IN STELLAR ENVIRONMENTS RELEVANT TO HIGH-DENSITY O–NE–MG CORES

International Nuclear Information System (INIS)

Suzuki, Toshio; Toki, Hiroshi; Nomoto, Ken’ichi

2016-01-01

Electron-capture and β-decay rates for nuclear pairs in the sd-shell are evaluated at high densities and high temperatures relevant to the final evolution of electron-degenerate O–Ne–Mg cores of stars with initial masses of 8–10 M ⊙ . Electron capture induces a rapid contraction of the electron-degenerate O–Ne–Mg core. The outcome of rapid contraction depends on the evolutionary changes in the central density and temperature, which are determined by the competing processes of contraction, cooling, and heating. The fate of the stars is determined by these competitions, whether they end up with electron-capture supernovae or Fe core-collapse supernovae. Since the competing processes are induced by electron capture and β-decay, the accurate weak rates are crucially important. The rates are obtained for pairs with A = 20, 23, 24, 25, and 27 by shell-model calculations in the sd-shell with the USDB Hamiltonian. Effects of Coulomb corrections on the rates are evaluated. The rates for pairs with A = 23 and 25 are important for nuclear Urca processes that determine the cooling rate of the O–Ne–Mg core, while those for pairs with A = 20 and 24 are important for the core contraction and heat generation rates in the core. We provide these nuclear rates at stellar environments in tables with fine enough meshes at various densities and temperatures for studies of astrophysical processes sensitive to the rates. In particular, the accurate rate tables are crucially important for the final fates of not only O–Ne–Mg cores but also a wider range of stars, such as C–O cores of lower-mass stars

Electron capture by multicharged ions at eV energies

International Nuclear Information System (INIS)

Havener, C.C.; Huq, M.S.; Meyer, F.W.; Phaneuf, R.A.

1988-01-01

A multicharged ion-atom merged-beams apparatus has been used in conjunction with the ORNL-ECR ion source to measure accurate absolute electron-capture cross sections in the energy range from below 1 eV/amu to 1500 eV/amu. Measurements for N/sup 3+,4+,5+/ /plus/ H(D) collisions indicate good agreement with available theoretical calculations. However, measurements with O 5+ /plus/ H(D) show an unexpected low-energy behavior which may be attributable to the ion-induced-dipole attraction between the reactants. Scaled Landau-Zener calculations presented here identify a transfer plus excitation channel which has the correct energy dependence at low energies. This finding suggest the need for a comprehensive coupled channel calculation which would include such product states. 25 refs., 8 figs

State-selective electron capture

International Nuclear Information System (INIS)

Dunford, R.W.; Liu, C.J.; Berry, H.G.; Pardo, R.C.; Raphaelian, M.L.A.

1988-01-01

We report results from a new atomic physics program using the Argonne PII ECR ion source which is being built as part of the upgrade of the Argonne Tandem-Linear Accelerator (ATLAS). Our initial experiments have been aimed at studying state-selective electron capture in ion-atom collisions using the technique of Photon Emission Spectroscopy. We are extending existing cross section measurements at low energy ( 6+ and O 7+ on He and H 2 targets in the energy range from 1-105 keV/amu. We also present uv spectra obtained in collisions of O 6+ , O 5+ and N 5+ on a sodium target. 4 refs., 2 figs., 1 tab

Electron capture in pseudo-two-electron systems: Ar8++He

International Nuclear Information System (INIS)

Kimura, M.; Olson, R.E.

1985-01-01

Molecular-structure calculations using the pseudopotential method have been performed on the (ArHe) 8+ system. The cross section for single-electron capture in Ar 8+ +He collisions was calculated for energies from 20 eV to 10 keV/amu. The perturbed-stationary-state method [M. Kimura, H. Sato, and R. E. Olson, Phys. Rev. A 28, 2085 (1983)], modified to include electron translation factors appropriate to two-electron systems, was used. The total cross section is relatively energy independent with a value of approximately 2.5 x 10 -15 cm 2 . The n = 4 level of Ar 7+ is found to be preferentially populated, with the 4f level being dominant

Atomic and nuclear parameters of single electron capture decaying nuclides

International Nuclear Information System (INIS)

Grau, A.

1981-01-01

Atomic and nuclear parameters of the following nuclides which decay by electron capture have been calculated: 37 A r, 41 C a, 49 V , 53 M n, 55 F e,59 N i, 68Ge,82 S r, 97 T c, 118 T e, 131 C s, 137 L a, 140 N d, 157 T b, 165 E r, 193 p t, 194 H g, and 205 P h The evaluation rules are included in the first part of the paper. The values and the associated uncertainties of the following parameters have been tabulated: decay energy, electron capture probabilities, fluorescence yield, electron emission and X-ray emission. (Author) 27 refs

Dipole-Guided Electron Capture Causes Abnormal Dissociations of Phosphorylated Pentapeptides

DEFF Research Database (Denmark)

Moss, Christopher L.; Chung, Thomas W.; Wyer, Jean

2011-01-01

energies and fluoranthene anion radicals in an ion trap resulted in the loss of a hydrogen atom, ammonia, and backbone cleavages forming complete series of sequence z ions. Elimination of phosphoric acid was negligible. In contrast, capture of lowenergy electrons by doubly charged ions in a Penning ion...... mapping of the potential energy surface provided structures for the precursor phosphopeptide dications. Electron attachment produces a multitude of low lying electronic states in charge-reduced ions that determine their reactivity in backbone dissociations and H- atom loss. The predominant loss of H atoms......Abstract Electron transfer and capture mass spectra of a series of doubly charged ions that were phosphorylated pentapeptides of a tryptic type (pS,A,A,A,R) showed conspicuous differences in dissociations of charge-reduced ions. Electron transfer from both gaseous cesium atoms at 100 keV kinetic...

Electronic radiative capture in solid targets

International Nuclear Information System (INIS)

Pregliasco, R.; Nemirovsky, I.; Suarez, S.

1988-01-01

X-ray spectra originating from electron radiative capture from aluminium target to K shell on F 9+ and F 8+ beams with 115MeV are studied. Using an electrostatic analyzer, it was obtained the charge fractions Fi to aluminiun thicknesses of 39 and 58 micrograms/cm 2 . These thicknesses are determined by the stopping power of alpha particles. (A.C.A.S.) [pt

Hole-capture properties of the electron-irradiation-induced deep-level H5 in p-type InP: A charge-controlled bistable model

International Nuclear Information System (INIS)

Bretagnon, T.; Bastide, G.; Rouzeyre, M.

1989-01-01

The electron-induced irradiated defect H 5 in Zn-doped p-type InP is an unusual hole trap, since its temperature-independent weak-hole capture cross section, σ c ∼10 -21 cm 2 , is 6 orders of magnitude lower than the value obtained from thermal-emission rates. We present a charge-controlled bistable configuration-coordinate diagram that explains this large difference and accounts for the optical-absorption properties. In addition, a microscopic D In n+ -Zn - defect, made by pairing under electrostatic attraction of the ionized acceptor Zn - and of a positively charged primitive defect D In n+ of the In sublattice, is tentatively proposed as a plausible complex at the origin of H 5

Resonant electron capture by aspartame and aspartic acid molecules.

Science.gov (United States)

Muftakhov, M V; Shchukin, P V

2016-12-30

The processes for dissociative electron capture are the key mechanisms for decomposition of biomolecules, proteins in particular, under interaction with low-energy electrons. Molecules of aspartic acid and aspartame, i.e. modified dipeptides, were studied herein to define the impact of the side functional groups on peptide chain decomposition in resonant electron-molecular reactions. The processes of formation and decomposition of negative ions of both aspartame and aspartic acid were studied by mass spectrometry of negative ions under resonant electron capture. The obtained mass spectra were interpreted under thermochemical analysis by quantum chemical calculations. Main channels of negative molecular ions fragmentation were found and characteristic fragment ions were identified. The СООН fragment of the side chain in aspartic acid is shown to play a key role like the carboxyl group in amino acids and aliphatic oligopeptides. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Electron capture Auger aftereffect of ammine cobalt complex

International Nuclear Information System (INIS)

Harada, Masayuki; Sano, Hirotoshi

1976-01-01

The study of ammine cobalt complex by luminescent Moessbauer spectrometry method was performed. The method was compared with hot atom chemistry method. The electron states in atoms are changed by the aftereffect on Auger emission following the electron capture process. The state of oxidation of disintegration products is usually higher than that of parent nuclei. However, sometimes, lower oxidation is seen in Fe-57, the daughter nuclei of Co-57. This phenomenon may be due to radiation chemistry process, and this effect can be observed by the luminescent Moessbauer spectrometry method. However, the range of the effect can not be seen by the Moessbauer method. Estimation showed that the Auger electrons stay within the surrounding area of the disintegration atom, and the effect does not reach to distant places. The yield of Fe-57 in the electron capture process of Co-57 in cobalt complex, the G-value, and the hot atom chemical yield were obtained. It is concluded that the aftereffect of the Auger process is the localized radiation chemistry effect. Good correlation was seen between the present method and the hot atom chemistry method. (Kato, T.)

Single-electron capture in He2+-D2 collisions

International Nuclear Information System (INIS)

Bordenave-Montesquieu, D.; Dagnac, R.

1994-01-01

Doubly differential cross sections of single-electron capture were measured for He 2+ impinging on a molecular deuterium target. The investigated collision energies are 4, 6 and 8 keV and the scattering angles range from 10' to 2 o 30' (laboratory frame). The exothermic capture leading to He + (1s) + D 2 +* was found to be the most important process at low energies and angles, whereas the endothermic channels leading to dissociative capture become the main processes at high scattering angles, i.e. at small impact parameters. (author)

The electron capture in 163Ho experiment - ECHo

Science.gov (United States)

Gastaldo, L.; Blaum, K.; Chrysalidis, K.; Day Goodacre, T.; Domula, A.; Door, M.; Dorrer, H.; Düllmann, Ch. E.; Eberhardt, K.; Eliseev, S.; Enss, C.; Faessler, A.; Filianin, P.; Fleischmann, A.; Fonnesu, D.; Gamer, L.; Haas, R.; Hassel, C.; Hengstler, D.; Jochum, J.; Johnston, K.; Kebschull, U.; Kempf, S.; Kieck, T.; Köster, U.; Lahiri, S.; Maiti, M.; Mantegazzini, F.; Marsh, B.; Neroutsos, P.; Novikov, Yu. N.; Ranitzsch, P. C. O.; Rothe, S.; Rischka, A.; Saenz, A.; Sander, O.; Schneider, F.; Scholl, S.; Schüssler, R. X.; Schweiger, Ch.; Simkovic, F.; Stora, T.; Szücs, Z.; Türler, A.; Veinhard, M.; Weber, M.; Wegner, M.; Wendt, K.; Zuber, K.

2017-06-01

Neutrinos, and in particular their tiny but non-vanishing masses, can be considered one of the doors towards physics beyond the Standard Model. Precision measurements of the kinematics of weak interactions, in particular of the 3H β-decay and the 163Ho electron capture (EC), represent the only model independent approach to determine the absolute scale of neutrino masses. The electron capture in 163Ho experiment, ECHo, is designed to reach sub-eV sensitivity on the electron neutrino mass by means of the analysis of the calorimetrically measured electron capture spectrum of the nuclide 163Ho. The maximum energy available for this decay, about 2.8 keV, constrains the type of detectors that can be used. Arrays of low temperature metallic magnetic calorimeters (MMCs) are being developed to measure the 163Ho EC spectrum with energy resolution below 3 eV FWHM and with a time resolution below 1 μs. To achieve the sub-eV sensitivity on the electron neutrino mass, together with the detector optimization, the availability of large ultra-pure 163Ho samples, the identification and suppression of background sources as well as the precise parametrization of the 163Ho EC spectrum are of utmost importance. The high-energy resolution 163Ho spectra measured with the first MMC prototypes with ion-implanted 163Ho set the basis for the ECHo experiment. We describe the conceptual design of ECHo and motivate the strategies we have adopted to carry on the present medium scale experiment, ECHo-1K. In this experiment, the use of 1 kBq 163Ho will allow to reach a neutrino mass sensitivity below 10 eV/ c 2. We then discuss how the results being achieved in ECHo-1k will guide the design of the next stage of the ECHo experiment, ECHo-1M, where a source of the order of 1 MBq 163Ho embedded in large MMCs arrays will allow to reach sub-eV sensitivity on the electron neutrino mass.

Orbital electron capture measurements with an internal-source spectrometer

International Nuclear Information System (INIS)

Gerner, C.P.

1978-01-01

Electron-capture measurements have been performed on 131 Ba and on 106 Agsup(m). For 131 Ba the L/K-and M/L-capture rations of the allowed decay have been measured to the 1048 keV level in 131 Cs. The Qsub(EC) value, the exchange- and overlap-correction factors Xsup(L/K) and Xsup(M/L) and the reduced capture ratios have been determined. For 106 Agsup(m) the L/K-capture ratio of the allowed decay has been measured to the 2757 keV level in 106 Pd. The Q value, the exchange- and overlap-correction factor Xsup(L/K) and the reduced L/K- capture ratio have been derived. The measurements indicate that agreement between experimentally determined capture ratios and exchange-corrected theoretical predictions is fairly good, both for allowed and for first-forbidden non-unique transitions. (Auth./C.F.)

Theory of nuclear excitation by electron capture for heavy ions

International Nuclear Information System (INIS)

Palffy, Adriana; Scheid, Werner; Harman, Zoltan

2006-01-01

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

Responses and mechanisms of positive electron affinity molecules in the N2 mode of the thermionic ionization detector and the electron-capture detector

International Nuclear Information System (INIS)

Jones, C.S.

1989-01-01

Very little knowledge has been acquired in the past on the mechanistic pathway by which molecules respond in the N 2 mode of the thermionic ionization detector. An attempt is made here to elucidate the response mechanism of the detector. The basic response mechanisms are known for the electron capture detector, and an attempt is made to identify the certain mechanism by which selected molecules respond. The resonance electron capture rate constant has been believed to be temperature independent, and investigations of the temperature dependence of electron capture responses are presented. Mechanisms for the N 2 mode of the thermionic ionization detector have been proposed by examining the detector response to positive electron affinity molecules and by measurement of the ions produced by the detector. Electron capture mechanisms for selected molecules have been proposed by examining their temperature dependent responses in the electron capture detector and negative ion mass spectra of the samples. In studies of the resonance electron capture rate constant, the relative responses of selected positive electron affinity molecules and their temperature dependent responses were investigated. Positive electron affinity did not guarantee large responses in the N 2 mode thermionic ionization detector. High mass ions were measured following ionization of samples in the detector. Responses in the electron capture detector varied with temperature and electron affinity

Multiple capture investigated by coincident electron spectroscopy in X7++Ar, at 70 keV

International Nuclear Information System (INIS)

Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A.

1999-01-01

The multiple electron capture in N 7+ + Ar and F 7+ (1s 2 ) + Ar systems is investigated at 70 keV with a new electron-recoil ion charge coincidence experiment. The whole electron energy range has been studied. Up to six electrons are found to be captured into autoionizing states. The recoil ion charge distribution associated with the emission of electrons is similar for both systems and found to be in good agreement with the prediction of Niehaus's model roughly adapted to take into account autoionizing cascades. New findings for the coincident double and triple captures are briefly discussed. A capture of an inner L-shell electron of Ar into the K-shell of the projectile is also observed in N 7+ + Ar collisions. (orig.)

Impact of electron-captures on nuclei near N = 50 on core-collapse supernovae

Science.gov (United States)

Titus, R.; Sullivan, C.; Zegers, R. G. T.; Brown, B. A.; Gao, B.

2018-01-01

The sensitivity of the late stages of stellar core collapse to electron-capture rates on nuclei is investigated, with a focus on electron-capture rates on 74 nuclei with neutron number close to 50, just above doubly magic 78Ni. It is demonstrated that variations in key characteristics of the evolution, such as the lepton fraction, electron fraction, entropy, stellar density, and in-fall velocity are about 50% due to uncertainties in the electron-capture rates on nuclei in this region, although thousands of nuclei are included in the simulations. The present electron-capture rate estimates used for the nuclei in this high-sensitivity region of the chart of isotopes are primarily based on a simple approximation, and it is shown that the estimated rates are likely too high, by an order of magnitude or more. Electron-capture rates based on Gamow-Teller strength distributions calculated in microscopic theoretical models will be required to obtain better estimates. Gamow-Teller distributions extracted from charge-exchange experiments performed at intermediate energies serve to guide the development and benchmark the models. A previously compiled weak-rate library that is used in the astrophysical simulations was updated as part of the work presented here, by adding additional rate tables for nuclei near stability for mass numbers between 60 and 110.

Interatomic Coulombic electron capture in atomic, molecular, and quantum dot systems

Directory of Open Access Journals (Sweden)

Bande Annika

2015-01-01

Full Text Available The interatomic Coulombic electron capture (ICEC process has recently been predicted theoretically for clusters of atoms and molecules. For an atom A capturing an electron e(ε it competes with the well known photorecombination, because in an environment of neutral or anionic neighboring atoms B, A can transfer its excess energy in the ultrafast ICEC process to B which is then ionized. The cross section for e(ε + A + B → A− + B+ + e(ε′ has been obtained in an asymptotic approximation based on scattering theory for several clusters [1,2]. It was found that ICEC starts dominating the PR for distances among participating species of nanometers and lower. Therefore, we believe that the ICEC process might be of importance in the atmosphere, in biological systems, plasmas, or in nanostructured materials. As an example for the latter, ICEC has been investigated by means of electron dynamics in a model potential for semiconductor double quantum dots (QDs [3]. In the simplest case one QD captures an electron while the outgoing electron is emitted from the other. The reaction probability for this process was found to be relatively large.

Κ-electron capture probability in 167Tm

International Nuclear Information System (INIS)

Sree Krishna Murty, G.; Chandrasekhar Rao, M.V.S.; Radha Krishna, K.; Bhuloka Reddy, S.; Satyanarayana, G.; Ramana Rao, P.V.; Sastry, D.L.

1990-01-01

The Κ-electron capture probability in the decay of 167 Tm for the first-forbidden transition 1/2 + →3/2 - was measured using the sum-coincidence method and employing a hyper-pure Ge system. The P Κ value is found to be 0.835±0.029, in agreement with the theoretical value of 0.829. (author)

Enhanced electron capture by fast heavy di-clusters exciting solids

International Nuclear Information System (INIS)

Cooney, P.J.; Faibis, A.; Kanter, E.P.; Koenig, W.; Maor, D.; Zabransky, B.J.

1985-01-01

The authors have studied the dependence of the charge-state-distributions of heavy-ion fragments resulting from the foil-induced dissociation of 4.2-MeV N 2 + ions on the thickness of the carbon target foil. The results were compared to those distributions measured for impact of 2.1-MeV N + projectiles. Whereas the charge-state distributions for atomic ion impact are already equilibrated in the thinnest targets used (2 μg/cm 2 ), those measured for molecular ion impact are strongly dependent on the target thickness, even for the thickest targets (100 + g/cm 2 ). The distributions for molecular-ion impact show a marked shift towards lower charge states, evidencing an enhanced electron capture probability over the case of monatomic ion impact. A quantitative model was developed to explain this phenomenon

Electron capture by Ne3+ ions from atomic hydrogen

International Nuclear Information System (INIS)

Rejoub, R.; Bannister, M.E.; Havener, C.C.; Savin, D.W.; Verzani, C.J.; Wang, J.G.; Stancil, P.C.

2004-01-01

Using the Oak Ridge National Laboratory ion-atom merged-beam apparatus, absolute total electron-capture cross sections have been measured for collisions of Ne 3+ ions with hydrogen (deuterium) atoms at energies between 0.07 and 826 eV/u. Comparison to previous measurements shows large discrepancies between 50 and 400 eV/u. Previously published molecular-orbital close-coupling (MOCC) calculations were performed over limited energy ranges, but show good agreement with the present measurements. Here MOCC calculations are presented for energies between 0.01 and 1000 eV/u for collisions with both H and D. For energies below ∼1 eV/u, an enhancement in the magnitude of both the experimental and theoretical cross sections is observed which is attributed to the ion-induced dipole attraction between the reactants. Below ∼4 eV/u, the present calculations show a significant target isotope effect

Electron capture by Ne3+ ions from atomic hydrogen

Science.gov (United States)

Rejoub, R.; Bannister, M. E.; Havener, C. C.; Savin, D. W.; Verzani, C. J.; Wang, J. G.; Stancil, P. C.

2004-05-01

Using the Oak Ridge National Laboratory ion-atom merged-beam apparatus, absolute total electron-capture cross sections have been measured for collisions of Ne3+ ions with hydrogen (deuterium) atoms at energies between 0.07 and 826 eV/u . Comparison to previous measurements shows large discrepancies between 50 and 400 eV/u . Previously published molecular-orbital close-coupling (MOCC) calculations were performed over limited energy ranges, but show good agreement with the present measurements. Here MOCC calculations are presented for energies between 0.01 and 1000 eV/u for collisions with both H and D. For energies below ˜1 eV/u , an enhancement in the magnitude of both the experimental and theoretical cross sections is observed which is attributed to the ion-induced dipole attraction between the reactants. Below ˜4 eV/u , the present calculations show a significant target isotope effect.

Ionization and single electron capture in collision of highly charged Ar16+ ions with helium

International Nuclear Information System (INIS)

Wang Fei; Gou Bingcong

2008-01-01

This paper uses the two-centre atomic orbital close-coupling method to study the ionization and the single electron capture in collision of highly charged Ar 16+ ions with He atoms in the velocity range of 1.2–1.9 a.u. The relative importance of single ionization (SI) to single capture (SC) is explored. The comparison between the calculation and experimental data shows that the SI/SC cross section ratios from this work are in good agreement with experimental data. The total single electron ionization cross sections and the total single electron capture cross sections are also given for this collision. The investigation of the partial electron capture cross section shows a general tendency of capture to larger n and l with increasing velocity from 1.2 to 1.9 a.u

Electron Capture in Proton Collisions with CO.

Science.gov (United States)

Stancil, P. C.; Schultz, D. R.; Kimura, M.; Gu, J.-P.; Hirsch, G.; Buenker, R. J.; Li, Y.

1999-10-01

Electron capture by protons following collisions with carbon monoxide is studied with a variety of theoretical approaches including quantal and semiclassical molecular-orbital close-coupling (MOCC) and classical trajectory Monte Carlo (CTMC) techniques. The MOCC treatments utilize potential surfaces and couplings computed for a range of H^+-CO orientation angles and C-O separations. Results including integral, differential, electronic state-selective, and vibrational state-selective cross sections will be presented for low- to intermediate-energies. Comparison with experiment will be made where possible and the relevance of the reaction in astrophysics and atmospheric physics will be discussed.

Asymptotic coulombic conditions in the electron capture process

International Nuclear Information System (INIS)

Corchs, S.E.; Maidagan, J.M.; Rivarola, R.D.

1990-01-01

Several first order perturbative approximations of the transition amplitude for electronic capture are studied. Different models in which the long range Coulomb potential is represented by different internuclear dependent phases, in the initial and final wave functions, are analysed and compared. (Author). 8 refs., 2 figs

Recent investigations on electronic capture in atomic collisions

International Nuclear Information System (INIS)

Rivarola, R.D.

1988-01-01

In this work, electron capture processes in ion-atom collisions at various impact energy ranges are dicussed: i) intermediate non-relativistic energy; ii) high energy; iii) high relativistic energy. Much attention is given to the development and use of distorted wave models. (A.C.A.S.) [pt

Search for new candidates for the neutrino-oriented mass determination by electron-capture

CERN Multimedia

Herfurth, F; Boehm, C; Blaum, K; Beck, D

2008-01-01

This proposal is part of an extended program dedicated to the neutrino-mass determination in the electron-capture sector, which aims at ultra-precise mass measurements by Penning traps in combination with cryogenic micro-calorimetry for atomic de-excitation measurements. Here, precise mass measurements with ISOLTRAP are proposed for the orbital electron-capture nuclides $^{194}$Hg and $^{202}$Pb, as well as their daughters, with the goal to determine accurately their Q-values. These values are expected to be the smallest ones among a great variety of known electron-capture precursors. Therefore, these nuclides are strong candidates for an improved electron-neutrino mass determination. We ask for 8 shifts of on-line beam at ISOLDE for mass measurements of $^{194}$Hg, $^{194}$ Au, $^{202}$Pb, and $^{202}$Tl at ISOLTRAP.

Double electron capture by protons in collisions with H2

International Nuclear Information System (INIS)

Salazar-Zepeda, M.H.; Gleason, Cristian; Gonzalez, Eduardo; Gonzalez-Magana, O.; Hinojosa, Guillermo

2010-01-01

Double electron capture of protons in collisions with molecular hydrogen in the energy range 1.5-10 keV was studied by measuring the resulting H - velocity distributions. In this paper, a technique that provides experimental evidence about double capture mechanisms is proposed. In addition, cross-sections for this process were measured in the energy range of 1-5 keV.

Electron capture by highly charged low-velocity ions

International Nuclear Information System (INIS)

Cocke, C.L.; Dubois, R.; Justiniano, E.; Gray, T.J.; Can, C.

1982-01-01

This paper describes the use of a fast heavy ion beam to produce, by bombardment of gaseous targets, highly-charged low-velocity recoil ions, and the use of these secondary ions in turn as projectiles in studies of electron capture and ionization in low-energy collision systems. The interest in collisions involving low-energy highly-charged projectiles comes both from the somewhat simplifying aspects of the physics which attend the long-range capture and from applications to fusion plasmas, astrophysics and more speculative technology such as the production of X-ray lasers. The ions of interest in such applications should have both electronic excitation and center-of-mass energies in the keV range and cannot be produced by simply stripping fast heavy ion beams. Several novel types of ion source have been developed to produce low-energy highly-charged ions, of which the secondary ion recoil source discussed in this paper is one. (Auth.)

Electron capture and energy-gain spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Taulbjerg, K.

1989-01-01

The applicability of translation energy spectroscopy as a tool to determine individual reaction cross sections in atomic collisions is analyzed with special emphasis on the electron capture process in highly charged ion collisions. A condition is derived to separate between higher collision energies where translation energy spectroscopy is problem free and lower energies where strong overlap of individual spectra features prohibits an analysis of the total translation energy spectrum by means of a simple deconvolution procedure. 8 refs., 6 figs.

Magnetar crust electron capture for {sup 55}Co and {sup 56}Ni

Energy Technology Data Exchange (ETDEWEB)

Liu, Jing-Jing; Liu, Dong-Mei [Hainan Tropical Ocean University, College of Marine Science and Technology, Sanya (China)

2018-01-15

Based on the relativistic mean-field effective interaction principle and random phase approximation theory in superstrong magnetic fields (SMFs), we present an analysis of the influence of SMFs on the electron Fermi energy, nuclear blinding energy, single-particle level structure and electron capture for {sup 55}Co, and {sup 56}Ni by the shell-model Monte Carlo method in the magnetar's crust. The electron capture rates increase by two orders of magnitude due to an increase in the electron Fermi energy and a change in single-particle level structure by SMFs. Then the rates decrease by more than two orders of magnitude due to an increase in the nuclear binding energy and a reduction in the electron Fermi energy by SMFs. (orig.)

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

International Nuclear Information System (INIS)

Mancev, Ivan; Milojevic, Nenad

2010-01-01

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.

Direct and indirect stabilisation mechanisms in multiple electron capture

Energy Technology Data Exchange (ETDEWEB)

Roncin, P. [Paris-11 Univ., 91 - Orsay (France). Lab. de Collisions Atomiques et Moleculaires; Barat, M. [Paris-11 Univ., 91 - Orsay (France). Lab. de Collisions Atomiques et Moleculaires; Gaboriaud, M.N. [Paris-11 Univ., 91 -Orsay (France). Lab. de Collisions Atomiques et Moleculaires; Szilagyi, Z.S. [Paris-11 Univ., 91 - Orsay (France). Lab. de Collisions Atomiques et Moleculaires; Kazansky, A.K. [Paris-11 Univ., 91 - Orsay (France). Lab. de Collisions Atomiques et Moleculaires

1995-05-01

During the last years both experimental and theoretical works have focused on the problem of the stabilisation of two excited electrons on the projectile. In this contribution we would like to give experimental examples of the two suggested mechanisms and their extension to multiple electron capture. Our data are discussed together with those obtained with other experimental techniques and with theoretical predictions. (orig./WL).

K-electron capture probability in 171Lu

International Nuclear Information System (INIS)

Mishra, N.R.; Vara Prasad, N.V.S.; Chandrasekhara Rao, M.V.S.; Satyanarayana, G.; Sastry, D.L.; Chintalapudi, S.N.

1999-01-01

The K-electron capture probability in the decay of 171 Lu to the 835.06 keV level of the daughter nucleus 171 Yb is measured to be 0.822 ± 0.027 involving two transitions, in agreement with the theoretical value 0.833. The experimental value is seen to be consistent with the mass prediction of the relationship due to Wapstra and Bos. (author)

Electron capture by highly stripped ions

International Nuclear Information System (INIS)

Greenland, P.T.

1981-06-01

This review describes theories of electron capture suitable for the description of rearrangement collisions between atomic hydrogen and completely stripped projectiles with charge greater than unity. The region of impact velocity considered lies between 0.05 and 3 au, which is of technological importance in fusion power devices. The semiclassical, impact parameter formalism is discussed and the use of atomic expansions at medium impact velocity is described. Experimental results for both completely and partially stripped projectiles are reviewed. The use of a molecular basis at low energy, and the role of pseudocrossings peculiar to the two centre Coulomb interaction are described. Finally, purely classical techniques, in which the electron wavefunction is represented by an ensemble of Kepler orbits are considered. The review was completed in February 1981. (author)

Multiple electron capture in close ion-atom collisions

International Nuclear Information System (INIS)

Schlachter, A.S.; Stearns, J.W.; Berkner, K.H.

1989-01-01

Collisions in which a fast highly charged ion passes within the orbit of K electron of a target gas atom are selected by emission of a K x-ray from the projectile or target. Measurement of the projectile charge state after the collision, in coincidence with the K x-ray, allows measurement of the charge-transfer probability during these close collisions. When the projectile velocity is approximately the same as that of target electrons, a large number of electrons can be transferred to the projectile in a single collision. The electron-capture probability is found to be a linear function of the number of vacancies in the projectile L shell for 47-MeV calcium ions in an Ar target. 18 refs., 9 figs

Electron capture cross-section of Au-Fe complex in silicon

International Nuclear Information System (INIS)

Ali, Akbar; Shafi, M; Majid, Abdul

2006-01-01

A deep level transient spectroscopy technique is applied to study the capture cross-section of an iron-gold complex. The thermal ionization energy obtained from emission rate data is found to be E c -0.36 eV. The Au-Fe complex is a single defect having a capture cross-section of 2.48x10 -16 cm 2 for electrons which is independent of temperature

Multiple capture investigated by coincident electron spectroscopy in X{sup 7+}+Ar, at 70 keV

Energy Technology Data Exchange (ETDEWEB)

Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A. [Universite Paul Sabatier, Toulouse (France). Lab. Collisions-Agregats-Reactivite

1999-11-01

The multiple electron capture in N{sup 7+} + Ar and F{sup 7+}(1s{sup 2}) + Ar systems is investigated at 70 keV with a new electron-recoil ion charge coincidence experiment. The whole electron energy range has been studied. Up to six electrons are found to be captured into autoionizing states. The recoil ion charge distribution associated with the emission of electrons is similar for both systems and found to be in good agreement with the prediction of Niehaus`s model roughly adapted to take into account autoionizing cascades. New findings for the coincident double and triple captures are briefly discussed. A capture of an inner L-shell electron of Ar into the K-shell of the projectile is also observed in N{sup 7+} + Ar collisions. (orig.) 10 refs.

Electron capture by multicharged ions from hydrogen atoms at eV energies

International Nuclear Information System (INIS)

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

1990-01-01

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

Differential cross sections for single-electron capture in He{sup 2+}-D collisions

Energy Technology Data Exchange (ETDEWEB)

Bordenave-Montesquieu, D.; Dagnac, R. [Centre National de la Recherche Scientifique (CNRS), 31 - Toulouse (France)]|[Toulouse-3 Univ., 31 (France)

1995-06-14

A translational energy spectroscopy technique was used to study single-electron capture into the He{sup +} (n = 2) and He{sup +} (n 3) states in He{sup 2+}-D collisions. Differential cross sections were determined at 4, 6 and 8 keV in the angular range 5`-1{sup o}30` (laboratory frame). As expected, single-electron capture into the n = 2 state was found to be the dominant process; total cross sections for capture into the He{sup +} (n = 3) state were compared to other experimental and theoretical results. (author).

Measurements of Pair Production and Electron Capture from the Continuum in Heavy Particle Collisions

CERN Multimedia

2002-01-01

Large transient Coulomb fields, which are generated in collisions of high-Z systems at sufficiently high energies, lead to copious production of electron-positron pairs. It has been suggested that these lepton pairs might mask signals arising from plasma phase interaction. Pair-production cross sections have been calculated by several authors with results which differ significantly from each other. Some of the electrons produced may be captured into bound states of the ion, thereby, reducing its charge state by one unit. This process which has been termed ``Electron Capture from Pair Production``, represents the only electron capture pro which increases with energy, and as such, will dominate all others in the ultrarelativistic energy regime. Ions having undergone this process would be lost from storage-type accelerators. The absolute cross sections for capture have been calculated with results which differ by as much as an order of magnitude. If as large as some of the calculations predict, Relativistic Heav...

Electron capture cross-section of Au-Fe complex in silicon

Energy Technology Data Exchange (ETDEWEB)

Ali, Akbar; Shafi, M; Majid, Abdul [Advance Materials Physics Laboratory, Department of Physics, Quaid-i-Azam University, Islamabad (Pakistan)

2006-10-15

A deep level transient spectroscopy technique is applied to study the capture cross-section of an iron-gold complex. The thermal ionization energy obtained from emission rate data is found to be E{sub c} -0.36 eV. The Au-Fe complex is a single defect having a capture cross-section of 2.48x10{sup -16} cm{sup 2} for electrons which is independent of temperature.

Accelerated Electron-Beam Formation with a High Capture Coefficient in a Parallel Coupled Accelerating Structure

Science.gov (United States)

Chernousov, Yu. D.; Shebolaev, I. V.; Ikryanov, I. M.

2018-01-01

An electron beam with a high (close to 100%) coefficient of electron capture into the regime of acceleration has been obtained in a linear electron accelerator based on a parallel coupled slow-wave structure, electron gun with microwave-controlled injection current, and permanent-magnet beam-focusing system. The high capture coefficient was due to the properties of the accelerating structure, beam-focusing system, and electron-injection system. Main characteristics of the proposed systems are presented.

Detection efficiency for radionuclides decaying by electron capture and gamma-Ray

International Nuclear Information System (INIS)

Grau, A.; Fernandez, A.

1985-01-01

In this paper, the electron capture partial counting efficiency vs the figure of merit for electron-capture and gamma-ray emitters has been computed. The radionuclides tabulated are 48 c r, 54 M n, 57 C o 56 N i, 72 S e, 73 A s, 85 S r, 88 Z r, 92 N b, 103 P d, 111 l n, 119 S b, 125 I , 139 C e and 152 D y. It has been assumed that the liquid is a toluene based scintillator solution in standard glass vials containing 15 cm 3 . (Author) 17 refs

Electron capture to the continuum from atomic hydrogen

International Nuclear Information System (INIS)

Glass, G.A.; Engar, P.; Berry, S.D.; Breinig, M.; Deserio, R.; Elston, S.B.; Sellin, I.A.

1984-01-01

The first known measurement of the differential cross section for electron capture to the continuum(ECC) from atomic hydrogen is presented. A 12 MeV beam of C 6+ ions traversed a static target of atomic hydrogen produced by an electron impact heated dissociation oven. The resulting ECC spectrum was obtained with a channel electron multiplier detector mounted at the exit of a 160 0 spherical sector electrostatic spectrometer with an angular acceptance of 2 0 . The ECC spectrum clearly shows the asymmetry generally associated with ECC spectra from gaseous targets. The ratio of the singly differential cross section of H to that of H 2 was found to be 0.80. 16 references, 3 figures

Gamow-Teller strength distributions and electron capture rates for 55Co and 56Ni

International Nuclear Information System (INIS)

Nabi, Jameel-Un; Rahman, Muneeb-Ur

2005-01-01

The Gamow-Teller strength (GT) distributions and electron capture rates on 55 Co and 56 Ni have been calculated using the proton-neutron quasiparticle random phase approximation theory. We calculate these weak interaction mediated rates over a wide temperature (0.01x10 9 -30x10 9 K) and density (10-10 11 gcm -3 ) domain. Electron capture process is one of the essential ingredients involved in the complex dynamics of supernova explosion. Our calculations of electron capture rates show differences with the reported shell model diagonalization approach calculations and are comparatively enhanced at presupernova temperatures. We note that the GT strength is fragmented over many final states

Electron loss and capture from low-charge-state oxygen projectiles in methane

International Nuclear Information System (INIS)

Santos, A C F; Wolff, W; Sant’Anna, M M; Sigaud, G M; DuBois, R D

2013-01-01

Absolute cross sections for single- and double-electron loss and single- and multiple-electron capture of 15–1000 keV oxygen projectiles (q = −1, 0, 1, 2) colliding with the methane molecule are presented. The experimental data are used to examine cross-section scaling characteristics for the electron loss of various projectiles. In addition, a modified version of the free-collision model was employed for the calculation of the single- and total-electron-loss cross sections of oxygen projectiles presented in this work. The comparison of the calculated cross sections with the present experimental data shows very good agreement for projectile velocities above 1.0 au. The comparison of the present single-electron-capture cross sections with other projectiles having the same charge shows good agreement, and a common curve can be drawn through the different data sets. (paper)

Determination of the Electron Neutrino Mass from Experiments on Electron-Capture Beta-Decay (EC)

CERN Multimedia

2002-01-01

The aim of the programme is to measure the electron-neutrino mass, for which at present an upper limit of 500~eV is known. \\\\ \\\\ The experiment studies the shape of the internal bremsstrahlung spectrum in electron-capture near its upper end-point and deduces a mass from small shape changes completely analogous to those in the well-known determination of the electron antineutrino mass in the tritium beta-minus decay. \\\\ \\\\ In a low-energy bremsstrahlung process, the capture takes place from a virtual S state associated with a radiative P~@A~S electromagnetic transition, and the resonant nature of the process leads to important enhancements of the photon intensities at low energy, in particular near the resonance energies co (X-rays). This effect gives this type of experiment a chance to compete with experiments on continuous beta spectra. \\\\ \\\\ The programme concentrates on two long-lived isotopes: \\\\ \\\\ 1)~~|1|6|3Ho. The Q value for this isotope has been found to be 2.6-2.7 keV. A detector specially construct...

Can the neutrino mass be measured using /sup 163/Ho electron capture

International Nuclear Information System (INIS)

Bennett, C.L.

1985-01-01

The safest limit on the neutrino mass comes from allowing the interference amplitude to be a free parameter in a fit to Springer's inner bremsstrahlung data while fixing the Q value to its upper limit based on the results of the relative capture rates from F. Hartmann's data. Since /sup 163/Ho was the most promising electron capture candidate for a neutrino mass detector, it is unlikely that electron capture will ever compete with tritium beta decay in terms of sensitivity to neutrino mass. The best fundamental thing that can be said is that the limit of the difference in the mass of the neutrino and its anti-particle is smaller in absolute value than for any other fermion anti-fermion pair

Vortex-Breakdown-Induced Particle Capture in Branching Junctions.

Science.gov (United States)

Ault, Jesse T; Fani, Andrea; Chen, Kevin K; Shin, Sangwoo; Gallaire, François; Stone, Howard A

2016-08-19

We show experimentally that a flow-induced, Reynolds number-dependent particle-capture mechanism in branching junctions can be enhanced or eliminated by varying the junction angle. In addition, numerical simulations are used to show that the features responsible for this capture have the signatures of classical vortex breakdown, including an approach flow aligned with the vortex axis and a pocket of subcriticality. We show how these recirculation regions originate and evolve and suggest a physical mechanism for their formation. Furthermore, comparing experiments and numerical simulations, the presence of vortex breakdown is found to be an excellent predictor of particle capture. These results inform the design of systems in which suspended particle accumulation can be eliminated or maximized.

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

Directory of Open Access Journals (Sweden)

K. Abe

2016-08-01

Full Text Available 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.

Double K-shell ionization in electron capture decay

International Nuclear Information System (INIS)

Intemann, R.L.

1985-01-01

Using a semirelativistic theory previously developed by the author, we have computed the total probability per K-capture event for the ionization of the remaining K electron for a dozen nuclides of interest. Based on hydrogenic wave functions and accurate to relative order (Zα) 2 , the theory takes into account the correlation between the two initial K electrons and permits adjustments for screening. Numerical results exhibiting the effects of screening are presented. A comprehensive comparison of the predictions of this theory, as well as those of other theoretical models, with recent experimental data is also given

ANISOTROPY EFFECTS IN ELECTRON-CAPTURE BY O6+ FROM ALIGNED NA-ASTERISK(3P)

NARCIS (Netherlands)

SCHLATMANN, AR; WIERSEMA, WP; HOEKSTRA, R; MORGENSTERN, R; OLSON, RE; PASCALE, J

1994-01-01

We report results of one electron capture by highly charged ions colliding with laser excited aligned Na*(3p). The 0 vi(10-->8) photon emission cross section after electron capture by the O6+ projectile is measured in the collision energy range 2-8 keV/amu. Effects of the Na*(3p) orbital alignment

Theory of inelastic multiphonon scattering and carrier capture by defects in semiconductors: Application to capture cross sections

Science.gov (United States)

Barmparis, Georgios D.; Puzyrev, Yevgeniy S.; Zhang, X.-G.; Pantelides, Sokrates T.

2015-12-01

Inelastic scattering and carrier capture by defects in semiconductors are the primary causes of hot-electron-mediated degradation of power devices, which holds up their commercial development. At the same time, carrier capture is a major issue in the performance of solar cells and light-emitting diodes. A theory of nonradiative (multiphonon) inelastic scattering by defects, however, is nonexistent, while the theory for carrier capture by defects has had a long and arduous history. Here we report the construction of a comprehensive theory of inelastic scattering by defects, with carrier capture being a special case. We distinguish between capture under thermal equilibrium conditions and capture under nonequilibrium conditions, e.g., in the presence of an electrical current or hot carriers where carriers undergo scattering by defects and are described by a mean free path. In the thermal-equilibrium case, capture is mediated by a nonadiabatic perturbation Hamiltonian, originally identified by Huang and Rhys and by Kubo, which is equal to linear electron-phonon coupling to first order. In the nonequilibrium case, we demonstrate that the primary capture mechanism is within the Born-Oppenheimer approximation (adiabatic transitions), with coupling to the defect potential inducing Franck-Condon electronic transitions, followed by multiphonon dissipation of the transition energy, while the nonadiabatic terms are of secondary importance (they scale with the inverse of the mass of typical atoms in the defect complex). We report first-principles density-functional-theory calculations of the capture cross section for a prototype defect using the projector-augmented wave, which allows us to employ all-electron wave functions. We adopt a Monte Carlo scheme to sample multiphonon configurations and obtain converged results. The theory and the results represent a foundation upon which to build engineering-level models for hot-electron degradation of power devices and the performance

Electron capture isotopes as cosmic ray 'hydrometers'

International Nuclear Information System (INIS)

Raisbeck, G.M.; Comstock, G.; Perron, C.; Yiou, F.

1975-01-01

Following our earlier work, a computer program has been developed to investigate in detail the survival of pure electron capture isotopes in cosmic rays as a function of their propagation conditions. It is found that this survival is very insensitive to certain parameters such as the type of path length distribution, but very sensitive to the density of the medium in which they are formed. Observation of these isotopes may thus provide clues as to this density. (orig.) [de

Kappa. -electron capture probability in sup 167 Tm

Energy Technology Data Exchange (ETDEWEB)

Sree Krishna Murty, G.; Chandrasekhar Rao, M.V.S.; Radha Krishna, K.; Bhuloka Reddy, S.; Satyanarayana, G.; Ramana Rao, P.V.; Sastry, D.L. (Andhra Univ., Visakhapatnam (India). Labs. for Nuclear Research); Chintalapudi, S.N. (Variable Energy Cyclotron Centre, Calcutta (India))

1990-07-01

The {Kappa}-electron capture probability in the decay of {sup 167}Tm for the first-forbidden transition 1/2{sup +}{yields}3/2{sup -} was measured using the sum-coincidence method and employing a hyper-pure Ge system. The P{sub {Kappa}} value is found to be 0.835{plus minus}0.029, in agreement with the theoretical value of 0.829. (author).

Limit on the radiative neutrinoless double electron capture of ^{36}Ar from GERDA Phase I

Science.gov (United States)

Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Barros, N.; Baudis, L.; Bauer, C.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; di Vacri, A.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Fedorova, O.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gooch, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hakenmüller, J.; Hegai, A.; Heisel, M.; Hemmer, S.; Heusser, G.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Csáthy, J. Janicskó; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Kish, A.; Klimenko, A.; Kneißl, R.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Medinaceli, E.; Miloradovic, M.; Mingazheva, R.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Palioselitis, D.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salamida, F.; Salathe, M.; Schmitt, C.; Schneider, B.; Schönert, S.; Schreiner, J.; Schütz, A.-K.; Schulz, O.; Schwingenheuer, B.; Selivanenko, O.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Stepaniuk, M.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wiesinger, C.; Wilsenach, H.; Wojcik, M.; Yanovich, E.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

2016-12-01

Neutrinoless double electron capture is a process that, if detected, would give evidence of lepton number violation and the Majorana nature of neutrinos. A search for neutrinoless double electron capture of ^{36}Ar has been performed with germanium detectors installed in liquid argon using data from Phase I of the GERmanium Detector Array ( Gerda) experiment at the Gran Sasso Laboratory of INFN, Italy. No signal was observed and an experimental lower limit on the half-life of the radiative neutrinoless double electron capture of ^{36}Ar was established: T_{1/2} > 3.6 × 10^{21} years at 90% CI.

Isomer depletion as experimental evidence of nuclear excitation by electron capture

Science.gov (United States)

Chiara, C. J.; Carroll, J. J.; Carpenter, M. P.; Greene, J. P.; Hartley, D. J.; Janssens, R. V. F.; Lane, G. J.; Marsh, J. C.; Matters, D. A.; Polasik, M.; Rzadkiewicz, J.; Seweryniak, D.; Zhu, S.; Bottoni, S.; Hayes, A. B.; Karamian, S. A.

2018-02-01

The atomic nucleus and its electrons are often thought of as independent systems that are held together in the atom by their mutual attraction. Their interaction, however, leads to other important effects, such as providing an additional decay mode for excited nuclear states, whereby the nucleus releases energy by ejecting an atomic electron instead of by emitting a γ-ray. This ‘internal conversion’ has been known for about a hundred years and can be used to study nuclei and their interaction with their electrons. In the inverse process—nuclear excitation by electron capture (NEEC)—a free electron is captured into an atomic vacancy and can excite the nucleus to a higher-energy state, provided that the kinetic energy of the free electron plus the magnitude of its binding energy once captured matches the nuclear energy difference between the two states. NEEC was predicted in 1976 and has not hitherto been observed. Here we report evidence of NEEC in molybdenum-93 and determine the probability and cross-section for the process in a beam-based experimental scenario. Our results provide a standard for the assessment of theoretical models relevant to NEEC, which predict cross-sections that span many orders of magnitude. The greatest practical effect of the NEEC process may be on the survival of nuclei in stellar environments, in which it could excite isomers (that is, long-lived nuclear states) to shorter-lived states. Such excitations may reduce the abundance of the isotope after its production. This is an example of ‘isomer depletion’, which has been investigated previously through other reactions, but is used here to obtain evidence for NEEC.

The Importance of Electron Captures in Core-Collapse Supernovae

International Nuclear Information System (INIS)

Langanke, K.; Sampaio, J.M.; Martinez-Pinedo, G.

2004-01-01

Nuclear physics plays an essential role in the dynamics of a type II supernova (a collapsing star). Recent advances in nuclear many-body theory allow now to reliably calculate the stellar weak-interaction processes involving nuclei. The most important process is the electron capture on finite nuclei with mass numbers A > 55. It is found that the respective capture rates, derived from modern many-body models, differ noticeably from previous, more phenomenological estimates. This leads to significant changes in the stellar trajectory during the supernova explosion, as has been found in state-of-the-art supernova simulations. (author)

Electron capture in very low energy collisions of multicharged ions with H and D in merged beams

International Nuclear Information System (INIS)

Havener, C.C.; Meyer, F.W.; Phaneuf, R.A.

1991-01-01

An ion-atom merged-beams technique is being used to measure total absolute electron-capture cross sections for multicharged ions in collisions with H (or D) in the energy range between 0.1 and 1000 eV/amu. Comparison between experiment and theory over such a large energy range constitutes a critical test for both experiment and theory. Total capture cross-section measurements for O 3+ H(D) and O 5+ + H(D) are presented and compared to state selective and differential cross section calculations. Landau-Zener calculations show that for O 5+ the sharp increase in the measured cross section below 1 eV/amu is partly due to trajectory effects arising from the ion-induced dipole interaction between the reactants. 20 refs., 8 figs

Investigation of the Mechanism of Electron Capture and Electron Transfer Dissociation of Peptides with a Covalently Attached Free Radical Hydrogen Atom Scavenger.

Science.gov (United States)

Sohn, Chang Ho; Yin, Sheng; Peng, Ivory; Loo, Joseph A; Beauchamp, J L

2015-11-15

The mechanisms of electron capture and electron transfer dissociation (ECD and ETD) are investigated by covalently attaching a free-radical hydrogen atom scavenger to a peptide. The 2,2,6,6-tetramethylpiperidin-l-oxyl (TEMPO) radical was chosen as the scavenger due to its high hydrogen atom affinity (ca. 280 kJ/mol) and low electron affinity (ca. 0.45 ev), and was derivatized to the model peptide, FQX TEMPO EEQQQTEDELQDK. The X TEMPO residue represents a cysteinyl residue derivatized with an acetamido-TEMPO group. The acetamide group without TEMPO was also examined as a control. The gas phase proton affinity (882 kJ/mol) of TEMPO is similar to backbone amide carbonyls (889 kJ/mol), minimizing perturbation to internal solvation and sites of protonation of the derivatized peptides. Collision induced dissociation (CID) of the TEMPO tagged peptide dication generated stable odd-electron b and y type ions without indication of any TEMPO radical induced fragmentation initiated by hydrogen abstraction. The type and abundance of fragment ions observed in the CID spectra of the TEMPO and acetamide tagged peptides are very similar. However, ECD of the TEMPO labeled peptide dication yielded no backbone cleavage. We propose that a labile hydrogen atom in the charge reduced radical ions is scavenged by the TEMPO radical moiety, resulting in inhibition of N-C α backbone cleavage processes. Supplemental activation after electron attachment (ETcaD) and CID of the charge-reduced precursor ion generated by electron transfer of the TEMPO tagged peptide dication produced a series of b + H (b H ) and y + H (y H ) ions along with some c ions having suppressed intensities, consistent with stable O-H bond formation at the TEMPO group. In summary, the results indicate that ECD and ETD backbone cleavage processes are inhibited by scavenging of a labile hydrogen atom by the localized TEMPO radical moiety. This observation supports the conjecture that ECD and ETD processes involve long

Warm Dark Matter Sterile Neutrinos in Electron Capture and Beta Decay Spectra

Directory of Open Access Journals (Sweden)

O. Moreno

2016-01-01

Full Text Available We briefly review the motivation to search for sterile neutrinos in the keV mass scale, as dark matter candidates, and the prospects to find them in beta decay or electron capture spectra, with a global perspective. We describe the fundamentals of the neutrino flavor-mass eigenstate mismatch that opens the possibility of detecting sterile neutrinos in such ordinary nuclear processes. Results are shown and discussed for the effect of heavy neutrino emission in electron capture in Holmium 163 and in two isotopes of Lead, 202 and 205, as well as in the beta decay of Tritium. We study the deexcitation spectrum in the considered cases of electron capture and the charged lepton spectrum in the case of Tritium beta decay. For each of these cases, we define ratios of integrated transition rates over different regions of the spectrum under study and give new results that may guide and facilitate the analysis of possible future measurements, paying particular attention to forbidden transitions in Lead isotopes.

'Mathematical model of K Capture and its implications'

International Nuclear Information System (INIS)

Angus, Andrew C.

2000-01-01

The mechanism of K Capture, the nuclear absorption of electron in the K shell, as induced by electricity, is explained in this article. Furthermore, a mathematical model of K Capture is formulated. Then, K Capture is applied to explain the negative results obtained by Steven Jones and the positive results obtained by Pons-Fleischmann in Deuterium Oxide Electrolysis Experiments. The most important implication of K Capture is the possibility of obtaining nuclear energy by fusion at low temperature from heavy water

Theory of nuclear excitation by electron capture for heavy ions

Energy Technology Data Exchange (ETDEWEB)

Gagyi-Palffy, A.

2006-07-01

The resonant process of nuclear excitation by electron capture (NEEC) in collisions involving highly-charged ions has been investigated theoretically. NEEC is a rare recombination process in which a free electron is captured into a bound shell of an ion with the simultaneous excitation of the nucleus. Total cross sections for NEEC followed by the radiative decay of the excited nucleus are presented for various collision systems. The possibility to observe the NEEC in scattering experiments with trapped or stored ions was discussed focusing on the cases with the largest calculated resonance strength. As the photons emitted in different channels of the electron recombination process are indistinguishable in the total cross section, the interference between NEEC followed by the radiative decay of the nucleus and radiative recombination was investigated. The angular distribution of the emitted photons in the recombination process provides means to discern the two processes. Angular differential cross sections for the emitted photons in the case of E2 nuclear transitions were presented for several heavy elements. (orig.)

Single-electron capture in He[sup 2+]-D[sub 2] collisions

Energy Technology Data Exchange (ETDEWEB)

Bordenave-Montesquieu, D.; Dagnac, R. (Toulouse-3 Univ., 31 (France))

1994-02-14

Doubly differential cross sections of single-electron capture were measured for He[sup 2+] impinging on a molecular deuterium target. The investigated collision energies are 4, 6 and 8 keV and the scattering angles range from 10' to 2[sup o]30' (laboratory frame). The exothermic capture leading to He[sup +] (1s) + D[sub 2][sup +*] was found to be the most important process at low energies and angles, whereas the endothermic channels leading to dissociative capture become the main processes at high scattering angles, i.e. at small impact parameters. (author).

Single-electron capture in low-energy Ar6+-He collisions

International Nuclear Information System (INIS)

Akguengoer, K.; Kamber, E.Y.; Ferguson, S.M.

1997-01-01

Double differential cross sections for state-selective single-electron capture processes in Ar 6+ -He collisions have been measured at laboratory energies between 75 and 900 eV and scattering angles between 0 and 8 . At the lowest energy, the zero-angle spectrum shows capture into Ar 5+ (4p) to be the most important channel. However, as the scattering angle is increased, a second peak appears at angles ≥2 and becomes more pronounced relative to the 4p capture channel. The energy spectra are interpreted qualitatively in terms of the reaction windows, which are calculated using the single-crossing Landau-Zener model. Total and differential cross sections are also measured and compared with available measurements and calculations. (orig.)

Measurements of Pair Production and Electron Capture from the Continuum in Heavy Particle Collisions

CERN Multimedia

2002-01-01

% WA99 \\\\ \\\\ Large transient Coulomb fields, which are generated in collisions of high-Z systems at sufficiently high energies, lead to copious production of electron-positron pairs. It has been suggested that these lepton pairs might mask signals arising from plasma phase interaction. Pair-production cross-sections have been calculated by several authors with results that differ significantly from each other. For very heavy ions and high energies, multiple pairs are expected to be formed even in single peripheral collisions. Perturbative and nonperturbative treatments lead to various predictions for the fractions of multiple pair formation out of the total cross-sections. Some of the electrons produced will be captured into bound states of the ion, thereby, reducing its charge state by one unit. This process which has been termed $^{\\prime\\prime}$Electron Capture from Pair Production$^{\\prime\\prime}$, represents the only electron capture process which increases with energy, and as such, will dominate all oth...

CDW-EIS model for single-electron capture in ion-atom collisions involving multielectronic targets

International Nuclear Information System (INIS)

Abufager, P N; MartInez, A E; Rivarola, R D; Fainstein, P D

2004-01-01

A generalization of the continuum distorted wave eikonal initial state (CDW-EIS) approximation, for the description of single-electron capture in ion-atom collisions involving multielectronic targets is presented. This approximation is developed within the framework of the independent electron model taking particular care of the representation of the bound and continuum target states. Total cross sections for single-electron capture from the K-shell of He, Ne and Ar noble gases by impact of bare ions are calculated. Present results are compared to previous CDW-EIS ones and to experimental data

Electron capture in collisions of S4+ with helium

International Nuclear Information System (INIS)

Wang, J.G.; Stancil, P.C.; Turner, A.R.; Cooper, D.L.; Schultz, D.R.; Rakovic, M.J.; Fritsch, W.; Zygelman, B.

2002-01-01

Charge transfer due to collisions of ground-state S 4+ (3s 2 1 S) ions with helium is investigated for energies between 0.1 meV u -1 and 10 MeV u -1 . Total and state-selective single electron capture (SEC) cross sections and rate coefficients are obtained utilizing the quantum mechanical molecular-orbital close-coupling (MOCC), atomic-orbital close-coupling (AOCC), classical trajectory Monte Carlo (CTMC) and continuum distorted wave methods. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained with the spin-coupled valence-bond approach. Previous data are limited to a calculation of the total SEC rate coefficient using the Landau-Zener model that is, in comparison to the results presented here, three orders of magnitude smaller. The MOCC SEC cross sections at low energy reveal a multichannel interference effect. True double capture is also investigated with the AOCC and CTMC approaches while autoionizing double capture and transfer ionization (TI) is explored with CTMC. SEC is found to be the dominant process except for E>200 keV u -1 when TI becomes the primary capture channel. Astrophysical implications are briefly discussed. (author)

Electron capture in collisions of S4+ with helium

Science.gov (United States)

Wang, J. G.; Turner, A. R.; Cooper, D. L.; Schultz, D. R.; Rakovic, M. J.; Fritsch, W.; Stancil, P. C.; Zygelman, B.

2002-07-01

Charge transfer due to collisions of ground-state S4+(3s2 1S) ions with helium is investigated for energies between 0.1 meV u-1 and 10 MeV u-1. Total and state-selective single electron capture (SEC) cross sections and rate coefficients are obtained utilizing the quantum mechanical molecular-orbital close-coupling (MOCC), atomic-orbital close-coupling (AOCC), classical trajectory Monte Carlo (CTMC) and continuum distorted wave methods. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained with the spin-coupled valence-bond approach. Previous data are limited to a calculation of the total SEC rate coefficient using the Landau-Zener model that is, in comparison to the results presented here, three orders of magnitude smaller. The MOCC SEC cross sections at low energy reveal a multichannel interference effect. True double capture is also investigated with the AOCC and CTMC approaches while autoionizing double capture and transfer ionization (TI) is explored with CTMC. SEC is found to be the dominant process except for E>200 keV u-1 when TI becomes the primary capture channel. Astrophysical implications are briefly discussed.

Comparison of the potentials used for the calculation of the resonant coherent electron capture and loss cross sections

International Nuclear Information System (INIS)

Pauly, N.; Dubus, A.; Roesler, M.

2003-01-01

For incident protons with velocities around 1 a.u., electron capture and loss processes are known to play an important role. In particular, electron emission as well as electronic stopping power are strongly influenced by the charge changing processes. Several different electron capture and loss processes have been identified [Solid State Phys. 43 (1990) 229], i.e. Auger valence band processes, shell processes and resonant coherent processes. In the latter, the incident projectile undergoes a periodic excitation due to the periodic crystalline potential so that an electron can be lost or captured. In the literature, several different choices have been made for the crystalline potential. It is precisely the aim of the present work to review and compare the various potentials used in the literature and to show the influence of this choice on the resonant coherent electron capture and loss cross sections

Single-photon emission associated with double electron capture in F9+ + C collisions

CERN Document Server

Elkafrawy, Tamer; Tanis, John A; Warczak, Andrzej

2016-01-01

Radiative double electron capture (RDEC), the one-step process occurring in ion-atom collisions, has been investigated for bare fluorine ions colliding with carbon. RDEC is completed when two target electrons are captured to a bound state of a projectile simultaneously with the emission of a single photon. This work is a follow-up to our earlier measurement of RDEC for bare oxygen projectiles, thus providing a recipient system free of electron-related Coulomb fields in both cases and allowing for the comparison between the two collision systems as well as with available theoretical studies. The most significant mechanisms of x-ray emission that may contribute to the RDEC energy region as background processes are also addressed.

Classical description of the electron capture to the continuum cusp formation in ion-atom collisions

International Nuclear Information System (INIS)

Illescas, Clara; Pons, B.; Riera, A.

2002-01-01

Classical calculations are used to describe the dynamics of the electron capture to the continuum (ECC) cusp formation in H + +He collisions. We illustrate the frontier character of the ECC electrons between capture and ionization, and confirm that it is a temporary capture, through projectile focusing, that is responsible for the ECC cusp. Furthermore, the cusp is not a divergence smoothed by the experiment, and is slightly shifted from the impact-velocity value because of the residual pull from the target after ionization. This shift is larger the smaller the nuclear velocity

Dynamic plasma screening effects on electron capture process in hydrogenic ion fully stripped ion collisions in dense plasmas

International Nuclear Information System (INIS)

Jung, Y.

1997-01-01

In dense plasmas, dynamic plasma screening effects are investigated on electron capture from hydrogenic ions by past fully stripped ions. The classical Bohr Lindhard model has been applied to obtain the electron capture probability. The interaction potential in dense plasmas is represented in terms of the longitudinal dielectric function. The classical straight-line trajectory approximation is applied to the motion of the projectile ion in order to visualize the electron capture probability as a function of the impact parameter, projectile energy, and plasma parameters. The electron capture probability including the dynamic plasma screening effect is always greater than that including the static plasma screening effect. When the projectile velocity is smaller than the electron thermal velocity, the dynamic polarization screening effect becomes the static plasma screening effect. When the projectile velocity is greater than the plasma electron thermal velocity, the interaction potential is almost unshielded. The difference between the dynamic and static plasma screening effects is more significant for low energy projectiles. It is found that the static screening formula obtained by the Debye Hueckel model overestimates the plasma screening effects on the electron capture processes in dense plasmas. copyright 1997 American Institute of Physics

Electron capture study of Ar[sup 7+] + He(H[sub 2]) by U. V. spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Bouchama, T. (Inst. de Physique, Univ. des Sciences et de la Technologie, Alger (Algeria)); El Motassadeq, A. (Lab. Traitement du Signal et Instrumentation, Univ. Jean Monnet, 42 Saint-Etienne (France)); Salmoun, A. (Univ. Cady Ayad, Marrakech (Morocco)); Druetta, M. (Lab. Traitement du Signal et Instrumentation, Univ. Jean Monnet, 42 Saint-Etienne (France)); Church, D.A. (Dept. of Physics, Texas AM Univ., College Station, TX (United States))

1993-11-01

Partial nl and total cross-sections for the low energy collisions Ar[sup 7+] + He(H[sub 2]) at 35-70 keV have been measured by photon spectroscopy. In addition to single electron capture, one electron capture with excitation of a core electron has been observed and measured. Comparisons with calculations based on the Extended Classical Over-Barrier (ECB) model and the assumption of conservation of angular momentum show good agreement between the experimental and predicted l-distributions. (orig.).

Single and double electron capture in collisions of highly ionized, decelerated Ge ions with Ne

International Nuclear Information System (INIS)

Stoehlker, T.; Kozhuharov, C.; Mokler, P.H.; Olson, R.E.; Stachura, Z.; Warczak, A.

1992-03-01

Experimental cross-sections for non-radiative single and double electron capture from Ne target into H-like Ge ions at low intermediate collision energies (4-12) MeV/u are presented. The results are compared with theoretical calculations and an empirical scaling rule. Information concerning the impact parameter dependence of electron capture is extracted using classical trajectory Monte Carlo calculations. (orig.)

State-selective electron capture into He-like U90+ ions in collisions with gaseous targets

International Nuclear Information System (INIS)

Ma, X.; Stoehlker, T.; Brinzanescu, O.; Fritzsche, S.; Ludziejewski, T.; Stachura, Z.; Warczak, A.

2000-11-01

For He-like uranium, a state-selective electron capture study was carried out for relativistic collisions with gaseous targets. In the experiment, the projectile X-ray emission produced by electron capture in collisions of 223 MeV/u U 90+ ions on N 2 , Ar, Kr, and Xe targets was measured in coincidence with down-charged U 89+ projectiles. Due to the large fine structure splitting in heavy ions, the well resolved Balmer transitions observed were used to deduce subshell sensitive cross-sections for electron capture. For this purpose a theoretical spectrum analysis and simulation was performed by taking into account electron cascades from states up to n = 40. The state-selective data are compared with theoretical calculations as a function of target atomic number. An overall agreement is found between the experimental data and the theoretical approaches applied except for the j-sensitive part. (orig.)

Electron capture by fast protons from helium-like ions

International Nuclear Information System (INIS)

Samanta, R.; Purkait, M.

2011-01-01

Four-body formalism of boundary corrected continuum intermediate state (BCCIS-4B) approximation have been applied to calculate the single-electron capture cross sections by fast protons through some helium-like ions in a large energy range from 30-1000 keV. In this model, distortion has been taken into account in the entrance channel. In the final channel, the passive electron plays the role of screening of the target ion. However, continuum states of the projectile and the electron in the field of the residual target ion are included. The comparison of the results is made with those of other theoretical investigations and experimental findings. The present calculated results are found to be in good agreement with the available experimental findings. (authors)

Limit on the radiative neutrinoless double electron capture of "3"6Ar from GERDA Phase I

International Nuclear Information System (INIS)

Agostini, M.; Balata, M.; D'Andrea, V.; Di Vacri, A.; Junker, M.; Laubenstein, M.; Allardt, M.; Domula, A.; Lehnert, B.; Schneider, B.; Wester, T.; Wilsenach, H.; Zuber, K.; Bakalyarov, A.M.; Belyaev, S.T.; Lebedev, V.I.; Zhukov, S.V.; Barabanov, I.; Bezrukov, L.; Doroshkevich, E.; Fedorova, O.; Gurentsov, V.; Kazalov, V.; Kuzminov, V.V.; Lubsandorzhiev, B.; Moseev, P.; Selivanenko, O.; Veresnikova, A.; Yanovich, E.; Barros, N.; Baudis, L.; Benato, G.; Kish, A.; Miloradovic, M.; Mingazheva, R.; Walter, M.; Bauer, C.; Hakenmueller, J.; Heisel, M.; Heusser, G.; Hofmann, W.; Kihm, T.; Kirsch, A.; Knoepfle, K.T.; Lindner, M.; Maneschg, W.; Salathe, M.; Schreiner, J.; Schwingenheuer, B.; Simgen, H.; Smolnikov, A.; Stepaniuk, M.; Wagner, V.; Wegmann, A.; Bellotti, E.; Belogurov, S.; Kornoukhov, V.N.; Bettini, A.; Brugnera, R.; Garfagnini, A.; Medinaceli, E.; Sada, C.; Sturm, K. von; Bode, T.; Csathy, J.J.; Lazzaro, A.; Schoenert, S.; Wiesinger, C.; Borowicz, D.; Brudanin, V.; Egorov, V.; Kochetov, O.; Nemchenok, I.; Rumyantseva, N.; Zhitnikov, I.; Zinatulina, D.; Caldwell, A.; Gooch, C.; Kneissl, R.; Liao, H.Y.; Majorovits, B.; Palioselitis, D.; Schulz, O.; Vanhoefer, L.; Cattadori, C.; Salamida, F.; Chernogorov, A.; Demidova, E.V.; Kirpichnikov, I.V.; Vasenko, A.A.; Falkenstein, R.; Freund, K.; Grabmayr, P.; Hegai, A.; Jochum, J.; Schmitt, C.; Schuetz, A.K.; Frodyma, N.; Misiaszek, M.; Panas, K.; Pelczar, K.; Wojcik, M.; Zuzel, G.; Gangapshev, A.; Gusev, K.; Hemmer, S.; Lippi, I.; Stanco, L.; Hult, M.; Lutter, G.; Inzhechik, L.V.; Klimenko, A.; Lubashevskiy, A.; Macolino, C.; Pandola, L.; Pullia, A.; Riboldi, S.; Shirchenko, M.

2016-01-01

Neutrinoless double electron capture is a process that, if detected, would give evidence of lepton number violation and the Majorana nature of neutrinos. A search for neutrinoless double electron capture of "3"6Ar has been performed with germanium detectors installed in liquid argon using data from Phase I of the GERmanium Detector Array (Gerda) experiment at the Gran Sasso Laboratory of INFN, Italy. No signal was observed and an experimental lower limit on the half-life of the radiative neutrinoless double electron capture of "3"6Ar was established: T_1_/_2 > 3.6 x 10"2"1 years at 90% CI. (orig.)

Limit on the radiative neutrinoless double electron capture of {sup 36}Ar from GERDA Phase I

Energy Technology Data Exchange (ETDEWEB)

Agostini, M.; Balata, M.; D' Andrea, V.; Di Vacri, A.; Junker, M.; Laubenstein, M. [INFN Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, Assergi (Italy); Allardt, M.; Domula, A.; Lehnert, B.; Schneider, B.; Wester, T.; Wilsenach, H.; Zuber, K. [Technische Universitaet Dresden, Institut fuer Kern- und Teilchenphysik, Dresden (Germany); Bakalyarov, A.M.; Belyaev, S.T.; Lebedev, V.I.; Zhukov, S.V. [National Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Barabanov, I.; Bezrukov, L.; Doroshkevich, E.; Fedorova, O.; Gurentsov, V.; Kazalov, V.; Kuzminov, V.V.; Lubsandorzhiev, B.; Moseev, P.; Selivanenko, O.; Veresnikova, A.; Yanovich, E. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Barros, N. [Technische Universitaet Dresden, Institut fuer Kern- und Teilchenphysik, Dresden (Germany); University of Pennsylvania, Philadelphia, PA (United States); Baudis, L.; Benato, G.; Kish, A.; Miloradovic, M.; Mingazheva, R.; Walter, M. [Physik Institut der Universitaet Zuerich, Zurich (Switzerland); Bauer, C.; Hakenmueller, J.; Heisel, M.; Heusser, G.; Hofmann, W.; Kihm, T.; Kirsch, A.; Knoepfle, K.T.; Lindner, M.; Maneschg, W.; Salathe, M.; Schreiner, J.; Schwingenheuer, B.; Simgen, H.; Smolnikov, A.; Stepaniuk, M.; Wagner, V.; Wegmann, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Bellotti, E. [Universita Milano Bicocca, Dipartimento di Fisica, Milan (Italy); INFN Milano Bicocca, Milan (Italy); Belogurov, S.; Kornoukhov, V.N. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Institute for Theoretical and Experimental Physics NRC ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Bettini, A.; Brugnera, R.; Garfagnini, A.; Medinaceli, E.; Sada, C.; Sturm, K. von [Dipartimento di Fisica e Astronomia dell' Universita di Padova, Padua (Italy); INFN Padova, Padua (Italy); Bode, T.; Csathy, J.J.; Lazzaro, A.; Schoenert, S.; Wiesinger, C. [Technische Universitaet Muenchen, Physik Department and Excellence Cluster Universe, Munich (Germany); Borowicz, D. [Jagiellonian University, Institute of Physics, Krakow (Poland); Joint Institute for Nuclear Research, Dubna (Russian Federation); Brudanin, V.; Egorov, V.; Kochetov, O.; Nemchenok, I.; Rumyantseva, N.; Zhitnikov, I.; Zinatulina, D. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Caldwell, A.; Gooch, C.; Kneissl, R.; Liao, H.Y.; Majorovits, B.; Palioselitis, D.; Schulz, O.; Vanhoefer, L. [Max-Planck-Institut fuer Physik, Munich (Germany); Cattadori, C.; Salamida, F. [INFN Milano Bicocca, Milan (Italy); Chernogorov, A.; Demidova, E.V.; Kirpichnikov, I.V.; Vasenko, A.A. [Institute for Theoretical and Experimental Physics NRC ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Falkenstein, R.; Freund, K.; Grabmayr, P.; Hegai, A.; Jochum, J.; Schmitt, C.; Schuetz, A.K. [Eberhard Karls Universitaet Tuebingen, Physikalisches Institut, Tuebingen (Germany); Frodyma, N.; Misiaszek, M.; Panas, K.; Pelczar, K.; Wojcik, M.; Zuzel, G. [Jagiellonian University, Institute of Physics, Krakow (Poland); Gangapshev, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Gusev, K. [Joint Institute for Nuclear Research, Dubna (Russian Federation); National Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Technische Universitaet Muenchen, Physik Department and Excellence Cluster Universe, Munich (Germany); Hemmer, S.; Lippi, I.; Stanco, L. [INFN Padova, Padua (Italy); Hult, M.; Lutter, G. [European Commission, JRC-Geel, Geel (Belgium); Inzhechik, L.V. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Moscow (Russian Federation); Klimenko, A. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); International University for Nature, Society and Man ' ' Dubna' ' , Dubna (Russian Federation); Lubashevskiy, A. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Macolino, C. [INFN Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, Assergi (Italy); LAL, CNRS/IN2P3, Universite Paris-Saclay, Orsay (France); Pandola, L. [INFN Laboratori Nazionali del Sud, Catania (Italy); Pullia, A.; Riboldi, S. [Universita degli Studi di Milano, Dipartimento di Fisica, Milan (Italy); INFN Milano (Italy); Shirchenko, M. [Joint Institute for Nuclear Research, Dubna (Russian Federation); National Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Collaboration: GERDA collaboration

2016-12-15

Neutrinoless double electron capture is a process that, if detected, would give evidence of lepton number violation and the Majorana nature of neutrinos. A search for neutrinoless double electron capture of {sup 36}Ar has been performed with germanium detectors installed in liquid argon using data from Phase I of the GERmanium Detector Array (Gerda) experiment at the Gran Sasso Laboratory of INFN, Italy. No signal was observed and an experimental lower limit on the half-life of the radiative neutrinoless double electron capture of {sup 36}Ar was established: T{sub 1/2} > 3.6 x 10{sup 21} years at 90% CI. (orig.)

First Calorimetric Measurement of OI-line in the Electron Capture Spectrum of $^{163}$Ho

CERN Document Server

Ranitzsch, P. C. -O.; Wegner, M.; Kempf, S.; Fleischmann, A.; Enss, C.; Gastaldo, L.; Herlert, A.; Johnston, K.

2014-01-01

The isotope $^{163}$Ho undergoes an electron capture process with a recommended value for the energy available to the decay, $Q_{\\rm EC}$, of about 2.5 keV. According to the present knowledge, this is the lowest $Q_{\\rm EC}$ value for electron capture processes. Because of that, $^{163}$Ho is the best candidate to perform experiments to investigate the value of the electron neutrino mass based on the analysis of the calorimetrically measured spectrum. We present for the first time the calorimetric measurement of the atomic de-excitation of the $^{163}$Dy daughter atom upon the capture of an electron from the 5s shell in $^{163}$Ho, OI-line. The measured peak energy is 48 eV. This measurement was performed using low temperature metallic magnetic calorimeters with the $^{163}$Ho ion implanted in the absorber. We demonstrate that the calorimetric spectrum of $^{163}$Ho can be measured with high precision and that the parameters describing the spectrum can be learned from the analysis of the data. Finally, we dis...

Probabilities and energies to obtain the counting efficiency of electron-capture nuclides, KLMN model

International Nuclear Information System (INIS)

Casas Galiano, G.; Grau Malonda, A.

1994-01-01

An intelligent computer program has been developed to obtain the mathematical formulae to compute the probabilities and reduced energies of the different atomic rearrangement pathways following electron-capture decay. Creation and annihilation operators for Auger and X processes have been introduced. Taking into account the symmetries associated with each process, 262 different pathways were obtained. This model allows us to obtain the influence of the M-electron-capture in the counting efficiency when the atomic number of the nuclide is high

Electron capture in ion atom and ion-ion collisions

International Nuclear Information System (INIS)

Barat, M.

1986-01-01

Electron capture (EC) by positive ions in collision with various targets has remained one of the most important subjects of research since the early 30's. From a theoretical point of view, EC is obviously a coupled 3-body problem: at least two cores and an active electron that jumps between them. Practical interest in EC arose in a variety of fields. Recently a renewed interest arose from the physics of thermonuclear fusion, where capture by highly charged ionic impurities were found to be an important process in tokamak devices. For that reasons, a number of reviews were devoted to this subject during the past years, including lectures given in various NATO advanced science institutes. The aim of this lecture is not at all to add a new review to this list, but (i) to summarize the very basis of the present theoretical approaches at low and moderate collision energy, (ii) to pinpoint some crucial difficulties in the theoretical treatment, (iii) to select specific examples which, to the taste of the author, reflect some present practical interest, or some significant advances. 48 references, 38 figures, 1 table

Theoretical treatment of electron capture and excitation in two-electron system ion-atom, atom-atom collisions at low to intermediate energy

International Nuclear Information System (INIS)

Kimura, M.

1986-01-01

A review of various theoretical treatments which have been used to study electron-capture and excitation processes in two-electron-system ion-atom, atom-atom collisions at low to intermediate energy is presented. Advantages as well as limitations associated with these theoretical models in application to practical many-electron ion-atom, atom-atom collisions are specifically pointed out. Although a rigorous theoretical study of many-electron systems has just begun so that reports of theoretical calculations are scarce to date in comparison to flourishing experimental activities, some theoretical results are of great interest and provide important information for understanding collision dynamics of the system which contains many electrons. Selected examples are given for electron capture in a multiply charged ion-He collision, ion-pair formation in an atom-atom collision and alignment and orientation in a Li + + He collision. (Auth.)

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

Science.gov (United States)

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. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Single electron capture by state-prepared Ar2+ projectiles in Ar

International Nuclear Information System (INIS)

Puerta, J.; Huber, B.A.

1985-03-01

Electron capture by state-selected Ar 2+ projectiles in Ar has been studied at low collision energies ( 2+ ions are measured explaining existing discrepancies of partial and total cross sections in the Ar 2+ /Ar collision system. Although highly excited metastable ions ( 5 D 4 0 , 3 F 4 0 ) represent a minor contamination of a non-prepared Ar 2+ beam (proportional1%), their contributions are found to dominate the capture process due to cross section values larger than 10 -15 cm 2 . (orig.)

Measurement of the activity of electron capturing isotopes

International Nuclear Information System (INIS)

Szoerenyi, A.

1980-01-01

In order to measure precisely the activity of electron capturing isotopes, an equipment was constructed for the detection the X-photons, the Auger- and the conversing electrons by a high-pressure, gas-flow 4π proportional counter. The proportional counter and the NaI(Tl) scintillation counter are placed in a common lead-shielding, thus, the equipment is suited for the measurement of radioisotopes decaying in coincidence. The structure of the proportional counter and of the pressure-control system are detailed. As an example, the energy spectra of a 109 Cd solution, taken at different pressures, are published. At a pressure of 1.1 MPa the 3 peaks are well separated. The results of an international test, in which the radioactivity of a 57 Co sample was determined, are published, too. (L.E.)

Electron capture from H(2s) by H+ at low energies

International Nuclear Information System (INIS)

Blanco, S.A.; Falcon, C.A.; Piacentini, R.D.

1986-01-01

Total cross sections for resonant electron capture by protons from metastable H(2s) targets have been computed in a six-state molecular close-coupling formalism. Transitions between degenerate sublevels of the L shell of the target occurring at large internuclear distances have been taken into account in the impact parameter approximation. Cross sections are presented for impact velocities between 0.05 and 0.3 au. The results are compared with theoretical calculations for capture from H(2s) by Li 3+ , C 6+ and N 7+ . (author)

Radiative double electron capture in fast heavy ion-atom collisions

International Nuclear Information System (INIS)

Yakhontov, V.L.; Amusia, M.Ya.

1996-01-01

Two-electron capture with emission of a single photon (TESP) in collisions of highly charged ions with light atoms is considered. Such a process is actually a time-reversed double photoionization but occurring at specific kinematics. In the lowest order in the inter-electron interaction, the TESP probability is determined by two diagrams which are evaluated analytically by means of the Coulomb Green function. The calculated ratio of the TESP and single recombination cross sections is in fair agreement with the data obtained in the recent experimental study of this phenomena. (orig.)

Interpretation of second Born amplitudes in electron capture

International Nuclear Information System (INIS)

McGuire, J.H.; Simony, P.R.; Weaver, O.L.; Macek, J.

1982-01-01

Exact sound Born amplitudes for 1s-1s electron capture are presented and interpreted in terms of contributions from intermediate states off the energy shell and on the energy shell. The classical model of Thomas corresponds to two-step scattering via one particular on-shell intermediate state. In the high-velocity limit for 1s-1s capture, this on-shell intermediate state of the Thomas model accounts for one-half of the total cross section, i.e., the second Born cross section. The other half comes from off-energy-shell intermediate states near the on-shell Thomas state. Above 5 MeV both the off-shell and on-shell amplitudes have a simple structure near the Thomas peak. Below 1 MeV, contributions from a broader range of intermediate states are evident in the amplitudes. Although the contribution from the Thomas state is not large below 1 MeV, other second Born effects are significant

Electron capture and excitation processes in H+-H collisions in dense quantum plasmas

Science.gov (United States)

Jakimovski, D.; Markovska, N.; Janev, R. K.

2016-10-01

Electron capture and excitation processes in proton-hydrogen atom collisions taking place in dense quantum plasmas are studied by employing the two-centre atomic orbital close-coupling (TC-AOCC) method. The Debye-Hückel cosine (DHC) potential is used to describe the plasma screening effects on the Coulomb interaction between charged particles. The properties of a hydrogen atom with DHC potential are investigated as a function of the screening strength of the potential. It is found that the decrease in binding energy of nl levels with increasing screening strength is considerably faster than in the case of the Debye-Hückel (DH) screening potential, appropriate for description of charged particle interactions in weakly coupled classical plasmas. This results in a reduction in the number of bound states in the DHC potential with respect to that in the DH potential for the same plasma screening strength, and is reflected in the dynamics of excitation and electron capture processes for the two screened potentials. The TC-AOCC cross sections for total and state-selective electron capture and excitation cross sections with the DHC potential are calculated for a number of representative screening strengths in the 1-300 keV energy range and compared with those for the DH and pure Coulomb potential. The total capture cross sections for a selected number of screening strengths are compared with the available results from classical trajectory Monte Carlo calculations.

Super-AGB Stars and their Role as Electron Capture Supernova Progenitors

Science.gov (United States)

Doherty, Carolyn L.; Gil-Pons, Pilar; Siess, Lionel; Lattanzio, John C.

2017-11-01

We review the lives, deaths and nucleosynthetic signatures of intermediate-mass stars in the range ≈6-12 M⊙, which form super-AGB stars near the end of their lives. The critical mass boundaries both between different types of massive white dwarfs (CO, CO-Ne, ONe), and between white dwarfs and supernovae, are examined along with the relative fraction of super-AGB stars that end life either as an ONe white dwarf or as a neutron star (or an ONeFe white dwarf), after undergoing an electron capture supernova event. The contribution of the other potential single-star channel to electron-capture supernovae, that of the failed massive stars, is also discussed. The factors that influence these different final fates and mass limits, such as composition, rotation, the efficiency of convection, the nuclear reaction rates, mass-loss rates, and third dredge-up efficiency, are described. We stress the importance of the binary evolution channels for producing electron-capture supernovae. Recent nucleosynthesis calculations and elemental yield results are discussed and a new set of s-process heavy element yields is presented. The contribution of super-AGB star nucleosynthesis is assessed within a Galactic perspective, and the (super-)AGB scenario is considered in the context of the multiple stellar populations seen in globular clusters. A brief summary of recent works on dust production is included. Last, we conclude with a discussion of the observational constraints and potential future advances for study into these stars on the low mass/high mass star boundary.

Single-electron capture in keV Ar15+...18++He collisions

NARCIS (Netherlands)

Knoop, S.; Fischer, D.; Xue, Y.; Zapukhlyak, M.; Osborne, C. J.; Ergler, Th; Ferger, T.; Braun, J.; Brenner, G.; Bruhns, H.; Dimopoulou, C.; Epp, S. W.; Martinez, A. J. Gonzalez; Sikler, G.; Orts, R. Soria; Tawara, H.; Kirchner, T.; Lopez-Urrutia, J. R. Crespo; Moshammer, R.; Ullrich, J.; Hoekstra, R.; Gonzales Martinez, A.J.

2008-01-01

Single-electron capture in 14 keV q(-1) Ar15+...18++He collisions is investigated both experimentally and theoretically. Partial cross sections and projectile scattering angle dependencies have been deduced from the target ion recoil momenta measured by the COLTRIMS technique. The comparison with

Calculation of current-voltage characteristics of electron-capture detectors

International Nuclear Information System (INIS)

Hinneburg, D.; Grosse, H.J.; Leonhardt, J.; Popp, P.

1983-01-01

Starting from the law of conservation of charge a stationary one-dimensional non-linear differential equation system is derived, which is applied to the direct-current mode of an electron-capture detector with parallel electrode plates. The theory takes into account space-charge, recombination, and inhomogeneous ionization and it deals with three kinds of charge carriers with different mobilities (positive and negative ions, electrons). Terms due to diffusion and gas-flow losses are excluded. The equations so constructed were programmed to get a means of calculating the charge and field distributions and the current-voltage characteristics as functions of various parameters of the detectors, the attaching gas and the ionization. For two cases the results are given. (author)

Electron capture into excited states of multi-charged ions

International Nuclear Information System (INIS)

Dijkkamp, D.

1985-01-01

This thesis deals with charge exchange reactions in slow collisions of multi-charged ions with neutral atoms or molecules. These reactions proceed very efficiently via a curve crossing mechanism, which leads to preferential population of excited states of the ion. The subsequent decay of these states leads to the emission of characteristic radiation. From wavelength resolved measurements of the absolute intensity of this radiation, cross sections for selective population of the excited (n,l-) states of the ion were determined. In addition, for some systems the total capture cross section was measured directly by means of charge state analysis of the secondary projectile ions. The role of charge exchange processes in fusion plasmas and in astrophysical plasmas is indicated. An experimental set-up is described with emphasis on the Electron Cyclotron Resonance Ion Source that was used in the experiments. Results for collisions of C 6+ , N 6+ , O 6+ and Ne 6+ with He, H 2 and Ar are presented as well as for electron capture from Li atoms by C 4+ and He 2+ . The interaction of the iso-electronic sequence C 4+ , N 5+ , O 6+ with atomic hydrogen, molecular hydrogen and helium is studied. First results for partial and total cross sections in collisions of fully stripped carbon, nitrogen and oxygen ions with atomic hydrogen are presented. These data are of particular importance for applications in fusion diagnostics. The data indicate that calculations of both molecular and atomic orbital type yield correct results, if an extended basis set is used. (Auth.)

Radiative capture of slow electrons by tungsten surface

International Nuclear Information System (INIS)

Artamonov, O.M.; Belkina, G.M.; Samarin, S.N.; Yakovlev, I.I.

1987-01-01

Isochromatic spectra of radiation capture of slow electrons by the surface of mono- and polycrystal tungsten recorded on 322 and 405 nm wave lengths are presented. The effect of oxygen adsorption on isochromates of the (110) face of tungsten monocrystal is investigated. The obtained isochromatic spectra are compared with energy band structure of tungsten. Based on the analysis of the obtained experimental results it is assumed that optical transition to the final state at the energy of 7.3 eV relatively to Fermi level is conditioned by surface states of the tungsten face (110)

Electron capture and ionization in collisions of multiply charged ions with H(2s)

International Nuclear Information System (INIS)

Errea, L F; Guzman, F; Illescas, Clara; Mendez, L; Pons, B; Riera, A; Suarez, J

2007-01-01

We present total cross sections for electron capture and ionization in collisions of B 5+ and Ne 10+ with H(2s), calculated using two methods: the semiclassical close-coupling molecular formalism and the eikonal-CTMC method. We have evaluated partial cross sections for capture into excited n-levels, required in plasma diagnostics

Molecular treatment of single (dissociative and nondissociative) and double electron capture in He2+ + H2 collisions

International Nuclear Information System (INIS)

Errea, L F; Macias, A; Mendez, L; Pons, B; Riera, A

2003-01-01

We present close-coupling calculations of total cross sections for single and double electron capture in He 2+ + H 2 collisions in the range 0.5- 25 keV amu -1 , and compare them with experimental data. We confirm the experimental finding that the dominant process for E ∼> 3 keV amu -1 is the nondissociative capture He 2+ + H 2 → He + (2l) + H 2 + (1σ g ), while at lower energies it is dissociative capture leading to He + (1s) + H + + H. Our calculations also show that He(1s2l) is the main output of the two electron capture process. (letter to the editor)

Quantum effects on the formation of negative hydrogen ion by polarization electron capture in partially ionized dense hydrogen plasmas

International Nuclear Information System (INIS)

Jung, Young-Dae; Kato, Daiji

2009-05-01

The quantum effects on the formation of the negative hydrogen ion (H - ) by the polarization electron capture process are investigated in partially ionized dense hydrogen plasmas. It is shown that the quantum effect strongly suppresses the electron capture radius as well as the cross section for the formation of the negative hydrogen ion. In addition, it has been found that the electron capture position is receded from the center of the projectile with decreasing the quantum effect of the plasma. (author)

Electron capture dissociation proceeds with a low degree of intramolecular migration of peptide amide hydrogens

DEFF Research Database (Denmark)

Rand, Kasper D; Adams, Christopher M; Zubarev, Roman A

2008-01-01

scrambling) that occurs during vibrational excitation of gas-phase ions. Unlike traditional collisional ion activation, electron capture dissociation (ECD) is not associated with substantial vibrational excitation. We investigated the extent of intramolecular backbone amide hydrogen (1H/2H) migration upon...... ECD using peptides with a unique selective deuterium incorporation. Our results show that only limited amide hydrogen migration occurs upon ECD, provided that vibrational excitation prior to the electron capture event is minimized. Peptide ions that are excessively vibrationally excited...

Measurement on K-electron capture probabilities in the decay of [sup 183]Re and [sup 168]Tm

Energy Technology Data Exchange (ETDEWEB)

Prasad, N.V.S.V.; Rao, M.V.S.C.; Reddy, S.B.; Satyanarayana, G.; Sastry, D.L. (Andhra Univ., Visakhapatnam (India). Swami Jnanananda Labs. for Nuclear Research); Murty, G.S.K. (UNDNJ, Newark, NJ (United States). Dept. of Radiology); Chintalapudi, S.N. (Inter University Consortium for DAE Facilities, Calcutta (India))

1994-03-01

The K-electron capture probabilities for the 5/2[sup +] to 3/2[sup -]transition in the electron capture decay of [sup 183]Re to the 208.805 keV level in the daughter [sup 183]W and for the 3[sup (+)] to 3[sup -]and 3[sup (+)] to 4[sup -] transitions in the electron capture decay of [sup 168]Tm to the 1541.4 keV and 1093.0 keV levels, respectively, in the daughter [sup 168]Er were measured for the first time using an x-[gamma] summing method. The experimental P[sub K] values are reported in this paper, together with those due to theory, and discussed. (Author).

Radiative muon capture and induced pseudoscalar coupling constant in nuclear matter

International Nuclear Information System (INIS)

Cheoun, Myung Ki; Kim, K S; Choi, T K

2003-01-01

Radiative muon capture is studied to investigate the induced pseudoscalar coupling constant g P in nuclear matter. According to the recent TRIUMF experiment for μ - p → nν μ γ, the g P was surprisingly larger than the value obtained from μ - p → nν μ experiment by as much as 44%. The result may affect seriously theoretical interpretations of the experimental results for the radiative muon captures in finite nuclei. In view of the recent TRIUMF result, the radiative muon capture in nuclear matter is revisited in a framework of the relativistic mean field theory

The Skyrme-TQRPA calculations of electron capture on hot nuclei in pre-supernova environment

Energy Technology Data Exchange (ETDEWEB)

Dzhioev, Alan A., E-mail: dzhioev@theor.jinr.ru; Vdovin, A. I., E-mail: vdovin@theor.jinr.ru [JINR, Bogoliubov Laboratory of Theoretical Physics (Russian Federation); Stoyanov, Ch., E-mail: stoyanov@inrne.bas.bg [Bulgarian Academy of Sciences, Institute for Nuclear Research and Nuclear Energy (Bulgaria)

2016-11-15

We combine the thermal QRPA approach with the Skyrme energy density functional theory (Skyrme–TQRPA) for modelling the process of electron capture on nuclei in supernova environment. For a sample nucleus, {sup 56}Fe, the Skyrme–TQRPA approach is applied to analyze thermal effects on the strength function of GT{sub +} transitions which dominate electron capture at E{sub e} ≤ 30 MeV. Several Skyrme interactions are used in order to verify the sensitivity of the obtained results to the Skyrme force parameters. Finite-temperature cross sections are calculated and the results are comparedwith those of the other model calculations.

Radiative double-electron capture in collisions of fast heavy ions with solid carbon targets

International Nuclear Information System (INIS)

Yakhontov, V.L.; Amusia, M.Y.

1997-01-01

Two-electron capture with an emission of a single photon (TESP) in collisions of highly charged ions with light atoms is considered. Such a process is actually a time-reversed double photoionization but occurring at specific kinematics. In the lowest order in the interelectron interaction, the TESP probability is determined by two diagrams which are evaluated analytically by means of the Coulomb Green close-quote s function. The calculated ratio of the radiative double-electron capture and single recombination cross sections is in fair agreement with the data obtained in the recent experimental study of this phenomenon. copyright 1997 The American Physical Society

Electron capture in proton collisions with alkali atoms as a three-body problem

International Nuclear Information System (INIS)

Avakov, G.V.; Blokhintsev, L.D.; Kadyrov, A.S.; Mukhamedzhanov, A.M.

1992-01-01

A previous paper proposed an approach to the calculation of electron transfer reactions in ion-atomic collisions based on the Faddeev three-body equations written in the Alt-Grassberger-Sandhas form. In the present work this approach is used to describe the electron capture in proton collisions with alkali atoms. The results of calculation of the total and partial cross sections for charge exchange in proton collisions with Li, Na, K and Rb atoms are presented. The calculated total cross sections are in good agreement with experiment for light target atoms. In going over to heavier targets, the theoretical total cross sections, while agreeing in form, tend to be larger than the experimental ones. The calculated partial cross sections for electron capture into the 2s state of the H atom are also in agreement with experiment. Some other partial cross sections were also calculated. (author)

Electron-capture negative-ion mass spectrometry: a technique for environmental contaminant identification

International Nuclear Information System (INIS)

Stemmler, E.A.

1986-01-01

Electron capture negative ion mass spectrometry (ECNIMS) is a method used to generate negative ions in a mass spectrometer by electron-molecule reactions. This technique facilitates the sensitive and selective detection of many toxic contaminants in environmental samples. Applications of this technique have been hindered by the limited understanding of instrumental parameters, by the questionable reproducibility of negative ion mass spectra, and by the inability to interpret negative ion mass spectra. Instrumental parameters which were important to control include the ion source temperature, ion source pressure, sample concentration, and the focus lens potential. The ability to obtain reproducible spectra was demonstrated by measurement of the spectrum of decafluorotriphenylphosphine (DFTPP) over a period of one year. Negative ion fragmentation mechanisms were studied by measuring the spectra of structurally related classes of compounds and isotopically labelled compounds. These results were combined with data obtained by other researchers. Fragmentations characteristic of particular functional groups or molecular structures have been summarized. From this data set, guidelines for the interpretation of electron capture negative ion mass spectra have been developed

Electron capture in collisions of S{sup 4+} with helium

Energy Technology Data Exchange (ETDEWEB)

Wang, J.G.; Stancil, P.C. [Department of Physics and Astronomy and Center for Simulational Physics, University of Georgia, Athens, GA (United States)]. E-mails: wangjg@physast.uga.edu; stancil@physast.uga.edu; Turner, A.R.; Cooper, D.L. [Department of Chemistry, University of Liverpool (United Kingdom)]. E-mail: dlc@liv.ac.uk; Schultz, D.R.; Rakovic, M.J. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)]. E-mails: schultzd@ornl.gov; milun@mail.phy.ornl.gov; Fritsch, W. [Abteilung Theoretische Physik, Hahn-Meitner-Institut Berlin, Berlin (Germany)]. E-mail: fritsch@hmi.de; Zygelman, B. [Department of Physics, University of Nevada, Las Vegas, NV (United States)]. E-mail: bernard@physics.unlv.edu

2002-07-28

Charge transfer due to collisions of ground-state S{sup 4+}(3s{sup 2} {sup 1}S) ions with helium is investigated for energies between 0.1 meV u{sup -1} and 10 MeV u{sup -1}. Total and state-selective single electron capture (SEC) cross sections and rate coefficients are obtained utilizing the quantum mechanical molecular-orbital close-coupling (MOCC), atomic-orbital close-coupling (AOCC), classical trajectory Monte Carlo (CTMC) and continuum distorted wave methods. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained with the spin-coupled valence-bond approach. Previous data are limited to a calculation of the total SEC rate coefficient using the Landau-Zener model that is, in comparison to the results presented here, three orders of magnitude smaller. The MOCC SEC cross sections at low energy reveal a multichannel interference effect. True double capture is also investigated with the AOCC and CTMC approaches while autoionizing double capture and transfer ionization (TI) is explored with CTMC. SEC is found to be the dominant process except for E>200 keV u{sup -1} when TI becomes the primary capture channel. Astrophysical implications are briefly discussed. (author)

Studing electronic structure of water molecules in aquocomplexes by the method of pions minus capture by hydrogen

International Nuclear Information System (INIS)

Dezhi, I.; Krumshtejn, Z.V.; Molnar, B.; Petrukhin, V.I.; Rybakov, V.N.; Suvorov, V.M.; Khorvat, D.; Tsisek, Z.; Yutlandov, I.A.

1980-01-01

Using the effect of electron shell state on π-meson capture by chemically bound hydrogen studied has been change of electron density in hydrogen atoms of water molecules bound into aquocomplexes. The fact of depression of π-meson capture probability by hydrogen of water in aquocomplexes has been established. The magnitudes of depression indicate essential decrease of electron density in a hydrogen atom of coordinated water. Interaction of ligands with oxygen-containing anions also essentially contributes to a magnitude of depression

Studies of collision mechanisms in electron capture by slow multiply charged ions

International Nuclear Information System (INIS)

Gilbody, H B; McCullough, R W

2004-01-01

We review measurements based on translational energy spectroscopy which are being used to identify and assess the relative importance of the various collision mechanisms involved in one-electron capture by slow multiply charged ions in collisions with simple atoms and molecules

Neutrino Signals in Electron-Capture Storage-Ring Experiments

Directory of Open Access Journals (Sweden)

Avraham Gal

2016-06-01

Full Text Available Neutrino signals in electron-capture decays of hydrogen-like parent ions P in storage-ring experiments at GSI are reconsidered, with special emphasis placed on the storage-ring quasi-circular motion of the daughter ions D in two-body decays P → D + ν e . It is argued that, to the extent that daughter ions are detected, these detection rates might exhibit modulations with periods of order seconds, similar to those reported in the GSI storage-ring experiments for two-body decay rates. New dedicated experiments in storage rings, or using traps, could explore these modulations.

A review of electron-capture and electron-transfer dissociation tandem mass spectrometry in polymer chemistry

International Nuclear Information System (INIS)

Hart-Smith, Gene

2014-01-01

Graphical abstract: -- Highlights: •ECD and ETD can produce unique and diagnostically useful polymer ion fragmentation data. •The operating principles of ECD and ETD are discussed in relation to other dissociation techniques. •Key characteristics of ECD and ETD spectra, as observed from biological analytes, are discussed. •ECD and ETD analyses are compared to CID analyses for different classes of synthetic polymer. -- Abstract: Mass spectrometry (MS)-based studies of synthetic polymers often characterise detected polymer components using mass data alone. However when mass-based characterisations are ambiguous, tandem MS (MS/MS) offers a means by which additional analytical information may be collected. This review provides a synopsis of two particularly promising methods of dissociating polymer ions during MS/MS: electron-capture and electron-transfer dissociation (ECD and ETD, respectively). The article opens with a summary of the basic characteristics and operating principles of ECD and ETD, and relates these techniques to other methods of dissociating gas-phase ions, such as collision-induced dissociation (CID). Insights into ECD- and ETD-based MS/MS, gained from studies into proteins and peptides, are then discussed in relation to polymer chemistry. Finally, ECD- and ETD-based studies into various classes of polymer are summarised; for each polymer class, ECD- and ETD-derived data are compared to CID-derived data. These discussions identify ECD and ETD as powerful means by which unique and diagnostically useful polymer ion fragmentation data may be generated, and techniques worthy of increased utilisation by the polymer chemistry community

Capture dynamics of hot electrons on quantum dots in RTDs studied by noise measurement

International Nuclear Information System (INIS)

Hees, S S; Kardynal, B E; Shields, A J; Farrer, I; Ritchie, D A

2008-01-01

We investigate the noise in quantum dot resonant tunnelling diodes (QDRTDs), where the quantum dots (QDs) placed in the collector experience electric fields that vary in a wide range. The trapping/detrapping of electrons on the QDs dominated the measured electrical noise. The model that we derived for the noise explains the experimental data well. The QD capture cross-section is one to two orders of magnitude smaller than the physical size of the QDs due to the reduced probability of capturing a hot electron on the QD. The model is a powerful tool to design the noise characteristics of QDRTD single photon-detectors

Muon capture on nuclei and the induced pseudoscalar coupling constant

International Nuclear Information System (INIS)

Hasinoff, M.D.

1996-11-01

Ordinary and radiative muon capture reactions are reviewed with regards to the evidence for a renormalization of the induced pseudoscalar coupling constant inside the nucleus. Emphasis is placed on the new results which have become available since the WEIN-92 conference. (authors)

An electron-microscopical analysis of capture and initial stages of penetration of nematodes by Arthrobotrys oligospora

NARCIS (Netherlands)

Veenhuis, Marten; Nordbring-Hertz, Birgit; Harder, Wim

1985-01-01

A detailed analysis was made of the capture and subsequent penetration of nematodes by the nematophagous fungus Arthrobotrys oligospora using different electron-microscopical techniques. Capture of nematodes by this fungus occurred on complex hyphal structures (traps) and was effectuated by an

Electron capture probabilities in sup 105 Ag

Energy Technology Data Exchange (ETDEWEB)

Chandrasekhar Rao, M.V.S.; Sree Krishna Murty, G.; Radha Krishna, K.; Bhuloka Reddy, S.; Satyanarayana, G.; Raghavaiah, C.V.; Sastry, D.L. (Andhra Univ., Visakhapatnam (India). Labs. for Nuclear Research); Chintalapudi, S.N. (Bhabha Atomic Research Centre, Calcutta (India). Variable Energy Cyclotron Centre)

1990-01-01

The K-electron capture probabilities for the 1/2{sup -}yields3/2{sup -} and 1/2{sup -}yields1/2{sup +} transitions in the decay of {sup 105}Ag were measured for the first time using the sum coincidence method. The experimental P{sub K} values were estimated to be 0.824{plus minus}0.042 and 0.851{plus minus}0.046 for the allowed and first-forbidden beta transitions, respectively in agreement with the theory. The P{sub L} experimental values to these two levels were also computed using the experimental P{sub L}/P{sub K} values reported by earlier authors. These results are also found to be consistent with the theoretical P{sub L} values. (orig.).

Pair production with electron capture in peripheral collisions of relativistic heavy ions

Energy Technology Data Exchange (ETDEWEB)

Bertulani, C.A.C.A. E-mail: bertu@if.ufrj.br; Dolci, D.D. E-mail: dolci@if.ufrj.br

2001-02-26

The production of electron-positron pairs with the capture of the electron in an atomic orbital is investigated for the conditions of the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). Dirac wave functions for the leptons are used, taking corrections to orders of Z{alpha} into account. The dependence on the transverse momentum transfer is studied and the accuracy of the equivalent photon approximation is discussed as a function of the nuclear charge.

Stroboscopic image capture: Reducing the dose per frame by a factor of 30 does not prevent beam-induced specimen movement in paraffin

International Nuclear Information System (INIS)

Typke, Dieter; Gilpin, Christopher J.; Downing, Kenneth H.; Glaeser, Robert M.

2007-01-01

Beam-induced specimen movement may be the major factor that limits the quality of high-resolution images of organic specimens. One of the possible measures to improve the situation that was proposed by Henderson and Glaeser [Ultramicroscopy 16 (1985) 139-150], which we refer to here as 'stroboscopic image capture', is to divide the normal exposure into many successive frames, thus reducing the amount of electron exposure-and possibly the amount of beam-induced movement-per frame. The frames would then be aligned and summed. We have performed preliminary experiments on stroboscopic imaging using a 200-kV electron microscope that was equipped with a high dynamic range Charge-coupled device (CCD) camera for image recording and a liquid N 2 -cooled cryoholder. Single-layer paraffin crystals on carbon film were used as a test specimen. The ratio F(g)/F(0) of paraffin reflections, calculated from the images, serves as our criterion for the image quality. In the series that were evaluated, no significant improvement of the F image (g)/F image (0) ratio was found, even though the electron exposure per frame was reduced by a factor of 30. A frame-to-frame analysis of image distortions showed that considerable beam-induced movement had still occurred during each frame. In addition, the paraffin crystal lattice was observed to move relative to the supporting carbon film, a fact that cannot be explained as being an electron-optical effect caused by specimen charging. We conclude that a significant further reduction of the dose per frame (than was possible with this CCD detector) will be needed in order to test whether the frame-to-frame changes ultimately become small enough for stroboscopic image capture to show its potential

Electron Capture Dissociation of Weakly Bound Polypeptide Polycationic Complexes

DEFF Research Database (Denmark)

Haselmann, Kim F; Jørgensen, Thomas J D; Budnik, Bogdan A

2002-01-01

as well as specific complexes of modified glycopeptide antibiotics with their target peptide. The weak nature of bonding is substantiated by blackbody infrared dissociation, low-energy collisional excitation and force-field simulations. The results are consistent with a non-ergodic ECD cleavage mechanism.......We have previously reported that, in electron capture dissociation (ECD), rupture of strong intramolecular bonds in weakly bound supramolecular aggregates can proceed without dissociation of weak intermolecular bonds. This is now illustrated on a series of non-specific peptide-peptide dimers...

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

Science.gov (United States)

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.

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

Science.gov (United States)

2012-01-26

... INTERNATIONAL TRADE COMMISSION [DN 2869] Certain Electronic Devices for Capturing and Transmitting... Interest AGENCY: U.S. International Trade Commission. ACTION: Notice. SUMMARY: Notice is hereby given that the U.S. International Trade Commission has received a complaint entitled In Re Certain Electronic...

The β+-electron capture decay of 73Kr

International Nuclear Information System (INIS)

Miehe, C.; Dessagne, P.; Pujol, Ch.; Walter, G.; Jonson, B.; Lindroos, M.

1999-01-01

The β + - electron capture decay of 73 Kr, produced at the ISOLDE CERN facility, has been studied by β-delayed proton and gamma emission. The established decay scheme involves 15 up to now unreported gamma emitting levels in 73 Br. The total proton branching ratio has been measured to be 0.0025±0.0003. From this work, a spin and parity 3/2 - is assigned to the 73 Kr ground state, on the basis of the allowed β branch to the 73 Br J π =1/2 - ground state and the feeding of the 5/2 + level located at 286 keV in 73 Br. (orig.)

Single-electron capture into Ar+ excited states in Ar2 + Na collision below 12 keV, 1

International Nuclear Information System (INIS)

Matsumoto, Atsushi; Tsurubuchi, Seiji; Okuno, Kazuhiko; Ohtani, Shunsuke; Iwai, Tsuruji.

1979-08-01

Emission spectra between 2800 and 6000 A have been observed at the ionic energies from 0.2 to 12 keV. Absolute measurements of emission cross-sections have been made for the emission lines coming from ArII excited states at 4 and 8 keV with a crossed-beam technique. Processes of single-electron capture into the ArII 4p- and 4p'-states, with exothermicity of a few eV, take place dominantly (--10 15 cm 2 ), while the endothermic processes producing ArII in the 4d- and 5s-states occur with small cross-sections. Sum of the cross-sections for electron capture into the excited states observed is comparable with the total single-electron capture cross-section estimated from attenuation measurements of ion currents. Possible errors and uncertainties are discussed. (author)

Single-electron capture into Ar+ excited states in Ar2++Na collision below 12 keV, 1

International Nuclear Information System (INIS)

Matsumoto, Atsushi; Tsurubuchi, Seiji; Iwai, Tsuruji; Ohtani, Shunsuke; Okuno, Kazuhiko

1980-01-01

Emission spectra between 2800 and 6000 A have been observed at the ionic energies from 0.2 to 12 keV. Absolute measurements of emission cross-sections have been made for the emission lines coming from ArII excited states at 4 and 8 keV with a crossed-beam technique. Processes of single-electron capture into the ArII 4p- and 4p'-states, with exothermicity of a few eV, take place dominantly (--10 -15 cm 2 ), while the endothermic processes producing ArII in the 4d- and 5s-states occur with small cross-sections. Sum of the cross-sections for electron capture into the excited states observed is comparable with the total single-electron capture cross-section estimated from attenuation measurements of ion currents. Possible errors and uncertainties are discussed. (author)

Neutron Induced Capture and Fission Processes on 238U

Directory of Open Access Journals (Sweden)

Oprea Cristiana

2016-01-01

Full Text Available Nuclear data on Uranium isotopes are of crucial interest for new generation of nuclear reactors. Processes of interest are the nuclear reactions induced by neutrons and in this work mainly the capture and the fission process on 238U will be analyzed in a wide energy interval. For slow and resonant neutrons the many levels Breit – Wigner formalism is necessary. In the case of fast and very fast neutrons up to 200 MeV the nuclear reaction mechanism implemented in Talys will be used. The present evaluations are necessary in order to obtain the field of neutrons in the design of nuclear reactors and they are compared with experimental data from literature obtained from capture and (n,xn processes.

Electron-irradiation-induced phase transformation in alumina

International Nuclear Information System (INIS)

Chen, C.L.; Arakawa, K.; Lee, J.-G.; Mori, H.

2010-01-01

In this study, electron-irradiation-induced phase transformations between alumina polymorphs were investigated by high-resolution transmission electron microscopy. It was found that the electron-irradiation-induced α → κ' phase transformation occurred in the alumina under 100 keV electron irradiation. It is likely that the knock-on collision between incident electrons and Al 3+ cations is responsible for the occurrence of electron-irradiation-induced phase transformation from α-alumina to κ'-alumina.

Application of a distorted wave model to electron capture in atomic collisions

International Nuclear Information System (INIS)

Deco, G.R.; Martinez, A.E.; Rivarola, R.D.

1988-01-01

In this work, it is presented the CDW-EIS approximation applied to the description of processes of electron capture in ion-atom collisions. Differential and total cross sections are compared to results obtained by other theoretical models, as well as, to experimental data. (A.C.A.S.) [pt

Monitoring compliance with transfusion guidelines in hospital departments by electronic data capture

DEFF Research Database (Denmark)

Norgaard, Astrid; De Lichtenberg, Trine Honnens; Nielsen, Jens

2014-01-01

-transfusion haemoglobin levels at the departmental level. In a tertiary care hospital, no such data were produced before this study. Our aim was to establish a Patient Blood Management database based on electronic data capture in order to monitor compliance with transfusion guidelines at departmental and hospital levels...

Cross sections of electron loss and capture for beams of O+ in water vapor from the energy range of 0,2 to 1,2 MeV

International Nuclear Information System (INIS)

Oliveira, Vitor Jesus de

2015-01-01

The study of the interactions between atoms and molecules is important for the knowledge of the cross sections of the processes that contribute to the deposition of energy by charged particle beams used in radiotherapy planning and transport particle simulation codes. Heavy ions, such as oxygen, induce many cellular and molecular damages in human cells.as a result of interaction between the projectile and atoms and molecules. The use of proton and carbon as the projectile interacting with water molecules is well characterized, however there are few studies with oxygen ions. In this work we are interested in the study of electron loss (projectile ionization) and electron capture with charge state 1+. The Pelletron accelerator of 1.7 MeV from the Federal University of Rio de Janeiro housed in the Atomic and Molecular collisions Laboratory (LACAM) has been used, which can accelerate atomic and molecular ions up to speeds of the order of hundredths of light speed, and consists of the source of negative ions, the Wien filter, the accelerator itself and the magnet load selector. The detection device used to evaluate the processes of interaction (capture and loss) between the beam of the O + and the water molecule is a Microchannel Plate (MCP) at the position sensitive anode. The collisions of O + beans are being studied in the range of 0.2 to 1.2 MeV with water vapor (Z = 10). Were obtained the respective absolute cross sections for electron loss and electron capture and compared with the cross sections of the molecule methane (CH4 → Z = 10), the isoelectronic water molecule. The experimental results show an agreement between the measurements with water and methane. Comparisons were made with results of theoretical models for electron loss using the 'Free Collision Model' and for capture the Bohr and Lindhard model. The theoretical results for electron loss show an agreement of experimental data with the model used. The model of Bohr and Lindhard describes

Removal of nonorthogonality in the Born theory used for study of electron capture in high energy ion-atom collisions

International Nuclear Information System (INIS)

Kimura, M.

1989-01-01

We show the complete removal of the nonorthogonality of wave functions between initial and final states in the Born theory. Hence, this treatment offers more realistic electron capture cross sections in high energy ion-atom collisions. Representative results for resonant electron capture in H + + H collision are discussed in conjunction with other perturbative results. 10 refs., 1 fig

Electron capture in collisions of Si3+ ions with atomic hydrogen from low to intermediate energies

Science.gov (United States)

Liu, C. H.; Liu, L.; Wang, J. G.

2014-07-01

The electron capture process for the Si3+(3s) + H(1s) collisions is investigated by the quantum-mechanical molecular orbital close-coupling (MOCC) method and by the two-center atomic orbital close-coupling (AOCC) method in the energy range of 10-5-10 keV/u and 0.8-200 keV/u, respectively. Total and state-selective cross sections are presented and compared with the available theoretical and experimental results. The present MOCC and AOCC results agree well with the experimental measurements, but show some discrepancy with the calculations of Wang et al. [Phys. Rev. A 74, 052709 (2006), 10.1103/PhysRevA.74.052709] at E > 40 eV/u because of the inclusion of rotational couplings, which play important roles in the electron capture process. At lower energies, the present results are about three to five times smaller than those of Wang et al. due to the difference in the molecular data at large internuclear distances. The energy behaviors of the electron capture cross sections are discussed on the basis of identified reaction mechanisms.

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

Science.gov (United States)

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.

Single electron capture in ion-atom collisions involving multielectronic targets

International Nuclear Information System (INIS)

Abufager, P.N.; Martinez, A.E.; Rivarola, R.D.; Fainstein, P.D.

2005-01-01

The generalized continuum distorted wave-eikonal initial state (GCDW-EIS) approximation is employed to study single electron capture by impact of protons on Ne and Ar targets. We analyze the contributions to the total cross sections coming from the different target shells. Present results are compared with theoretical calculations obtained using the previous CDW-EIS formulation and to experimental data in order to show the importance of the description of the bound and continuum target states in the entry and exit channels, respectively

The effect of electron-electron interaction induced dephasing on electronic transport in graphene nanoribbons

Energy Technology Data Exchange (ETDEWEB)

Kahnoj, Sina Soleimani; Touski, Shoeib Babaee [School of Electrical and Computer Engineering, University of Tehran, P.O. Box 14395-515, Tehran (Iran, Islamic Republic of); Pourfath, Mahdi, E-mail: pourfath@ut.ac.ir, E-mail: pourfath@iue.tuwien.ac.at [School of Electrical and Computer Engineering, University of Tehran, P.O. Box 14395-515, Tehran (Iran, Islamic Republic of); Institute for Microelectronics, TU Wien, Gusshausstrasse 27–29/E360, 1040 Vienna (Austria)

2014-09-08

The effect of dephasing induced by electron-electron interaction on electronic transport in graphene nanoribbons is theoretically investigated. In the presence of disorder in graphene nanoribbons, wavefunction of electrons can set up standing waves along the channel and the conductance exponentially decreases with the ribbon's length. Employing the non-equilibrium Green's function formalism along with an accurate model for describing the dephasing induced by electron-electron interaction, we show that this kind of interaction prevents localization and transport of electrons remains in the diffusive regime where the conductance is inversely proportional to the ribbon's length.

Probabilities and energies to obtain the counting efficiency of electron-capture nuclides. KLMN model

International Nuclear Information System (INIS)

Galiano, G.; Grau, A.

1994-01-01

An intelligent computer program has been developed to obtain the mathematical formulae to compute the probabilities and reduced energies of the different atomic rearrangement pathways following electron-capture decay. Creation and annihilation operators for Auger and X processes have been introduced. Taking into account the symmetries associated with each process, 262 different pathways were obtained. This model allows us to obtain the influence of the M-electro capture in the counting efficiency when the atomic number of the nuclide is high. (Author)

Correlated electron capture and inner-shell excitation measurements in ion-atom collisions

International Nuclear Information System (INIS)

Tanis, J.A.; Bernstein, E.M.; Clark, M.W.

1985-01-01

In an ion-atom collision projectile excitation and charge transfer (electron capture) may occur together in a single encounter. If the excitation and capture are correlated, then the process is called resonant transfer and excitation (RTE); if they are uncorrelated, then the process is termed nonresonant transfer and excitation (NTE). Experimental work to date has shown the existence of RTE and provided strong evidence for NTE. Results presented here provide information on the relative magnitudes of RTE and NTE, the charge state dependence of RTE, the effect of the target momentum distribution on RTE, the magnitude of L-shell RTE compared to K-shell RTE, and the target Z dependences of RTE and NTE. 15 refs., 5 figs

Electron Capture in Slow Collision of He^2++H : Revisited

Science.gov (United States)

Krstic, Ps

2003-05-01

Very early experimental data (Fite et al. al., Proc. R. Soc. A 268, 527 (1962)) for He^2++H, recent ORNL measurements for Ne^2+ + H and our theoretical estimates suggest that the electron capture cross sections for these strongly exoergic collision systems drop slower toward low collision energies than expected from previous theories. We perform a theoretical study to establish and understand the true nature of this controversy. The calculations are based on the Hidden Crossings MOCC method, augmented with rotational and turning point effects.

Single-electron capture for 2-8 keV incident energy and direct scattering at 6 keV in He2+-He collisions

International Nuclear Information System (INIS)

Bordenave-Montesquieu, D.; Dagnac, R.

1992-01-01

We studied the single-electron capture as well as the direct processes occurring when a He 2+ ion is scattered by a He target. Doubly differential cross sections were measured for single-electron capture with a collision energy ranging from 2 to 8 keV and a scattering angle varying from 10' to 3 o 30' (laboratory frame). Single-electron capture into excited states of He + was found to be the dominant process, confirming a previous experimental study. Elastic scattering and ionization differential cross sections were measured for E = 6 keV. (Author)

Studying electron-PAG interactions using electron-induced fluorescence

Science.gov (United States)

Narasimhan, Amrit; Grzeskowiak, Steven; Ostrander, Jonathan; Schad, Jonathon; Rebeyev, Eliran; Neisser, Mark; Ocola, Leonidas E.; Denbeaux, Gregory; Brainard, Robert L.

2016-03-01

In extreme ultraviolet (EUV) lithography, 92 eV photons are used to expose photoresists. Typical EUV resists are organic-based and chemically amplified using photoacid generators (PAGs). Upon exposure, PAGs produce acids which catalyze reactions that result in changes in solubility. In EUV lithography, photo- and secondary electrons (energies of 10- 80 eV) play a large role in PAG acid-production. Several mechanisms for electron-PAG interactions (e.g. electron trapping, and hole-initiated chemistry) have been proposed. The aim of this study is to explore another mechanism - internal excitation - in which a bound PAG electron can be excited by receiving energy from another energetic electron, causing a reaction that produces acid. This paper explores the mechanism of internal excitation through the analogous process of electron-induced fluorescence, in which an electron loses energy by transferring that energy to a molecule and that molecule emits a photon rather than decomposing. We will show and quantify electron-induced fluorescence of several fluorophores in polymer films to mimic resist materials, and use this information to refine our proposed mechanism. Relationships between the molecular structure of fluorophores and fluorescent quantum yield may aid in the development of novel PAGs for EUV lithography.

Electron capture and transfer-ionization processes in {sup 4}He{sup 2+}+Ar collision at 12.5 keV amu{sup -1}

Energy Technology Data Exchange (ETDEWEB)

Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A.; Benhenni, M. [Laboratoire Collisions, Agregats, Reactivite, IRSAMC, UMR 5589 CNRS and Universite Paul Sabatier, 31062 Toulouse Cedex (France)

1998-05-14

Electron emission in the {sup 4}He{sup 2+}+Ar collisional system has been investigated at 35 deg. and 12.5 keV amu{sup -1} collision velocity, in coincidence with the recoil target ion charges. Direct single ionization is found to be negligible with respect to single-electron capture. Contributions of transfer-ionization processes are stressed in the production of Ar{sup 2+} to Ar{sup 4+} ions; those of direct ionization, double excitation of the target and double capture into autoionization states of helium are instead found to be much less probable. Among the two-electron processes which explain the formation of Ar{sup 2+} ions, the double capture into autoionizing states of helium remains unimportant with respect to a pure transfer ionization process (one captured electron plus one ionized electron). The measured predominant production of Ar{sup 3+} ions illustrates the role played by three-electron processes, mainly a two-electron transfer accompanied by a single-target ionization. Finally, the formation of Ar{sup 4+} ions is connected with more complex transfer ionization processes. A qualitative analysis of these results is made within the quasimolecular approach. (author). Letter-to-the-editor.

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

International Nuclear Information System (INIS)

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 2 2pn/ell/ (n ≥ 6) in O 6+ + He collisions. Enhancement of high angular momentum /ell/ in specific 1s 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 2 2pn/ell/ configurations is verified by means of Landau-Zener model calculations. 32 refs., 4 figs

Radiative electron capture for F8+ and F9+ ions in collisions with a He gas target

International Nuclear Information System (INIS)

Kawatsura, K.; Richard, P.; Tawara, H.

1981-01-01

The x rays from the radiative electron capture (REC) to the projectile K-shell were investigated for F 8+ and F 9+ ions incident on the He target atoms in the projectile energy range from 15 to 40 MeV. The peak energies of the K-REC x-ray spectra were found to decrease linearly with a decrease of the projectile energies as expected and extrapolated to the correct ls binding energies at zero velocity. According to theory the distribution width of the REC energies should be independent of the binding energy of electrons in the projectile ions. However, it is found that this width for F 8+ ions is systematically smaller by 20% than that for F 9+ ions. The measured REC cross sections for F 9+ ions are slightly larger than twice those for F 8+ ions and the total REC cross sections for F 8+ and F 9+ ions were found to be more than three orders of magnitude smaller than the total electron capture cross sections and the capture cross sections into excited states

Negative meson capture in hydrogen

International Nuclear Information System (INIS)

Baird, T.J.

1977-01-01

The processes of deexcitation and capture of negative mesons and hadrons in atomic hydrogen are investigated. Only slow collisions in which the projectile-atom relative velocity is less than one atomic unit are considered, and the motion of the incident particle is treated classically. For each classical trajectory the probability of ionizing the hydrogen atom is determined, together with the energy spectrum of the emitted electron. Ionization probabilities are calculated using the time-dependent formulation of the perturbed stationary state method. Exact two-center electronic wave functions are used for both bound and continuum states. The total ionization cross section and electron energy spectrum have been calculated for negative muons, kaons and antiprotons at incident relative velocities between 0.04 and 1.0 atomic units. The electron energy spectrum has a sharp peak for electron kinetic energies on the order of 10 -3 Rydbergs. The ionization process thus favors the emission of very slow electrons. The cross section for ionization with capture of the incident particle was calculated for relative kinetic energies greater than 1.0 Rydberg. Since ionization was found to occur with the emission of electrons of nearly zero kinetic energy, the fraction of ionizing collisions which result in capture decreases very rapidly with projectile kinetic energy. The energy distributions of slowed down muons and hadrons were also computed. These distributions were used together with the capture cross section to determine the distribution of kinetic energies at which capture takes place. It was found that most captures occur for kinetic energies slightly less than 1.0 Rydbergs with relatively little capture at thermal energies. The captured particles therefore tend to go into very large and loosely found orbits with binding energies less than 0.1 Rydbergs

ELECTRON-CAPTURE FROM LI BY B-5+, N-5+ AND BE-4+ IONS

NARCIS (Netherlands)

HOEKSTRA, R; OLSON, RE; FOLKERTS, HO; WOLFRUM, E; PASCALE, J; DEHEER, FJ; MORGENSTERN, R; WINTER, H

1993-01-01

We present state selective experimental and theoretical results for electron capture in B-5+ and N5+-Li collisons at energies in the range of 1-10 keV amu-1. Experimentally we have used photon emission spectroscopy in the VUV and visible spectral range and theoretically we have performed classical

Ultralow energy calibration of LUX detector using Xe 127 electron capture

Science.gov (United States)

Akerib, D. S.; Alsum, S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Biesiadzinski, T. P.; Boulton, E. M.; Brás, P.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Currie, A.; Cutter, J. E.; Davison, T. J. R.; Dobi, A.; Druszkiewicz, E.; Edwards, B. N.; Fallon, S. R.; Fan, A.; Fiorucci, S.; Gaitskell, R. J.; Genovesi, J.; Ghag, C.; Gilchriese, M. G. D.; Hall, C. R.; Hanhardt, M.; Haselschwardt, S. J.; Hertel, S. A.; Hogan, D. P.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Jacobsen, R. G.; Ji, W.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Knoche, R.; Larsen, N. A.; Lenardo, B. G.; Lesko, K. T.; Lindote, A.; Lopes, M. I.; Manalaysay, A.; Mannino, R. L.; Marzioni, M. F.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morad, J. A.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; O'Sullivan, K.; Oliver-Mallory, K. C.; Palladino, K. J.; Pease, E. K.; Rhyne, C.; Shaw, S.; Shutt, T. A.; Silva, C.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Sumner, T. J.; Szydagis, M.; Taylor, D. J.; Taylor, W. C.; Tennyson, B. P.; Terman, P. A.; Tiedt, D. R.; To, W. H.; Tripathi, M.; Tvrznikova, L.; Uvarov, S.; Velan, V.; Verbus, J. R.; Webb, R. C.; White, J. T.; Whitis, T. J.; Witherell, M. S.; Wolfs, F. L. H.; Xu, J.; Yazdani, K.; Young, S. K.; Zhang, C.

2017-12-01

We report an absolute calibration of the ionization yields (Qy ) and fluctuations for electronic recoil events in liquid xenon at discrete energies between 186 eV and 33.2 keV. The average electric field applied across the liquid xenon target is 180 V /cm . The data are obtained using low energy Xe 127 electron capture decay events from the 95.0-day first run from LUX (WS2013) in search of weakly interacting massive particles. The sequence of gamma-ray and x-ray cascades associated with I 127 deexcitations produces clearly identified two-vertex events in the LUX detector. We observe the K-(binding energy, 33.2 keV), L-(5.2 keV), M-(1.1 keV), and N-(186 eV) shell cascade events and verify that the relative ratio of observed events for each shell agrees with calculations. The N-shell cascade analysis includes single extracted electron (SE) events and represents the lowest-energy electronic recoil in situ measurements that have been explored in liquid xenon.

Neutron-induced capture cross sections via the surrogate reaction method

International Nuclear Information System (INIS)

Boutoux, G.; Jurado, B.; Aiche, M.; Barreau, G.; Capellan, N.; Companis, I.; Czajkowski, S.; Dassie, D.; Haas, B.; Mathieu, L.; Meot, V.; Bail, A.; Bauge, E.; Daugas, J. M.; Faul, T.; Gaudefroy, L.; Morel, P.; Pillet, N.; Roig, O.; Romain, P.; Taieb, J.; Theroine, C.; Burke, J.T.; Companis, I.; Derkx, X.; Gunsing, F.; Matea, I.; Tassan-Got, L.; Porquet, M.G.; Serot, O.

2011-01-01

The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. This technique enables neutron-induced cross sections to be extracted for nuclear reactions on short-lived unstable nuclei that otherwise can not be measured. This technique has been successfully applied to determine the neutron-induced fission cross sections of several short-lived nuclei. In this work, we investigate whether this powerful technique can also be used to determine of neutron-induced capture cross sections. For this purpose we use the surrogate reaction 174 Yb( 3 He, pγ) 176 Lu to infer the well known 175 Lu(n, γ) cross section and compare the results with the directly measured neutron-induced data. This surrogate experiment has been performed in March 2010. The experimental technique used and the first preliminary results will be presented. (authors)

Electron capture in slow collisions of multicharged ions with hydrogen atoms using merged beams

International Nuclear Information System (INIS)

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

1991-01-01

Absolute total electron-capture cross-section mesurements are reported for collisions of O 3+ and O 4+ with atomic hydrogen in the energy range 1-1000 eV /amu using merged beams. The data are compared with available coupled-states theoretical calculations. (orig.)

Electron capture and loss to continuum states in gases and solids

International Nuclear Information System (INIS)

Sellin, I.A.; Laubert, R.

1981-01-01

A key feature of our experimental procedure is the easy interchange of short gaseous and thin solid targets at the same physical position, with all apparatus aperture sizes, dimensions, positions, and other experimental details unaltered. It has therefore been possible to cancel most systematic apparatus effects in comparing gaseous and solid target results. By using single ion-atom collision techniques, by using bare and few-electron ions of appreciably higher charge than heretofore, by extending the velocity range of measurement appreciably above that of earlier experiments, and by studying charge-state variation over an appreciably wider range than used previously, we have been able to test experimentally features of continuum electron-capture and -loss theories which have been inaccessible in previous experiments. (orig./TW)

Measurement of K-electron capture probability in the decay of 87Y

International Nuclear Information System (INIS)

Prasad, N.V.S.V.; Murty, G.S.K.; Rao, M.V.S.C.; Sastry, D.L.

1993-01-01

The K-electron capture probability for the 1/2 - to 3/2 - transition in the decay of 87 Y to the 873.0 keV level in the daughter 87 Sr was measured for the first time using an x-γ summing method. The experimental P K value was found to be 0.911 ± 0.047, in agreement with the theoretical value of 0.878. (author)

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

Energy Technology Data Exchange (ETDEWEB)

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.

The calorimetric spectrum of the electron-capture decay of $^{163}$Ho. A preliminary analysis of the preliminary data

CERN Document Server

De Rújula, A.

2015-01-01

It is in principle possible to measure directly the electron neutrino mass (or masses and mixing angles) in weak electron-capture decays. The optimal nuclide in this respect is $^{163}$Ho. The favoured experimental technique, currently pursued in various experiments (ECHo, HOLMES and NuMECS) is "calorimetric". The calorimetric energy spectrum is a sum over the unstable vacant orbitals, or "holes", left by the electrons weakly captured by the nucleus. We discuss the current progress in this field and analize the preliminary data. Our conclusion is that, as pointed out by Robertson, the contribution of two-hole states is not negligible. But --in strong contradistinction with the tacit conclusion of previous comparisons of theory and observations-- we find a quite satisfactory agreement. A crucial point is that, in the creation of secondary holes, electron shakeoff and not only electron shakeup must be taken into account.

Electron capture in collisions between O6+ ions and H2O molecules

NARCIS (Netherlands)

Bodewits, D.; Hoekstra, R.

By means of photon emission spectroscopy, state selective electron capture cross section for low energy (0.1-7.5 keV/amu) collisions of O6+ on H2O molecules have been measured. Over the range of interaction energies the state selective cross sections change strongly, i.e., by factors up to 5, while

Electronic data capture in a rural African setting: evaluating experiences with different systems in Malawi

OpenAIRE

King, Carina; Hall, Jenny; Banda, Masford; Beard, James; Bird, Jon; Kazembe, Peter; Fottrell, Ed

2014-01-01

Background\\ud \\ud As hardware for electronic data capture (EDC), such as smartphones or tablets, becomes cheaper and more widely available, the potential for using such hardware as data capture tools in routine healthcare and research is increasing.\\ud \\ud Objective\\ud \\ud We aim to highlight the advantages and disadvantages of four EDC systems being used simultaneously in rural Malawi: two for Android devices (CommCare and ODK Collect), one for PALM and Windows OS (Pendragon), and a custom-b...

Electron-capture Isotopes Could Constrain Cosmic-Ray Propagation Models

Science.gov (United States)

Benyamin, David; Shaviv, Nir J.; Piran, Tsvi

2017-12-01

Electron capture (EC) isotopes are known to provide constraints on the low-energy behavior of cosmic rays (CRs), such as reacceleration. Here, we study the EC isotopes within the framework of the dynamic spiral-arms CR propagation model in which most of the CR sources reside in the galactic spiral arms. The model was previously used to explain the B/C and sub-Fe/Fe ratios. We show that the known inconsistency between the 49Ti/49V and 51V/51Cr ratios remains also in the spiral-arms model. On the other hand, unlike the general wisdom that says the isotope ratios depend primarily on reacceleration, we find here that the ratio also depends on the halo size (Z h) and, in spiral-arms models, also on the time since the last spiral-arm passage ({τ }{arm}). Namely, EC isotopes can, in principle, provide interesting constraints on the diffusion geometry. However, with the present uncertainties in the lab measurements of both the electron attachment rate and the fragmentation cross sections, no meaningful constraint can be placed.

Neutrinoless double electron capture decay of 54-Fe

International Nuclear Information System (INIS)

Bikit, I; Krmar, M.; Slivka, J.; Anicin, I.; Veskovic, M.; Convie, L.

1994-01-01

Double electron capture is the only decay mode of 54-Fe to 54-Cr. The most probable KK capture in the 0 nu case would lead to an otherwise not populated excited state of 54-Cr with the energy of 668 + - KeV. This process has not been yet investigated, probably because the lacking theoretical arguments on the nature of the excited state which could favour the decay. On the other hand if we suppose that gamma transition from this state to the ground state is allowed the 668 KeV gamma ray would be a definite signature of the process. Having in mind the relatively large abundance of 54-Fe in natural iron, a large quantity of iron in some shields in low level gamma spectroscopy systems and the low and flat background in the 668 keV spectral region, we easily estimate that the sensitivity for measuring the half life of this process is quit high. With our equipment consisting of a 25% efficiency commercial HP Ge spectrometer, placed in a cubic shaped iron shield with wall thickness of 25 cm from the background spectrum measured for only 100 days we calculated the lower limit for the half life of the 0 nu EC.EC decay of 54-Fe on the 68% confidence level to be T > 3.1 *10 sup 2 sup 2 years. 2 figs., 5 refs. (author)

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

Science.gov (United States)

2012-02-27

... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-831] Certain Electronic Devices for Capturing and Transmitting Images, and Components Thereof AGENCY: U.S. International Trade Commission... Trade Commission on January 10, 2012, under section 337 of the Tariff Act of 1930, as amended, 19 U.S.C...

Electron capture by C2+ and Ti2+ ions in H and H2

International Nuclear Information System (INIS)

Nutt, W.L.; McCullough, R.W.; Gilbody, H.B.

1978-01-01

Cross sections for electron capture by C 2+ and Ti 2+ ions in H and H 2 have been determined within the energy range 0.5 to 14 keV from measurements made using a tungsten-tube furnace to provide a target of highly dissociated hydrogen. (author)

CDW (continuum distorted wave) type approximation for electron capture at large angles

International Nuclear Information System (INIS)

Fojon, O.A.; Maidagan, J.M.

1990-01-01

A calculation is made for the probability of electron capture in shell K at great angles using a second order symmetrical model used related to the continuum distorted wave (CDW) approximation. The influence of Coulomb distortion of nuclei is studied and compared with OBK and CIS type calculations. Numerical results are compared with experimental results of the collision of H + on C at intermediate energies. (Author). 19 refs., 2 figs

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

Science.gov (United States)

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

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.

Correlation between atomic negative muon capture and electron distribution in organic sp2-hybridization compounds CxHyClz

International Nuclear Information System (INIS)

Sakai, Yoichi; Tominaga, Takeshi; Ikuta, Shigeru

1986-01-01

The atomic negative muon capture ratios determined experimentally in organic sp 2 -hybridization compound, C x H y Cl z , were compared with the electron populations of carbon atomic orbitals obtained by an ab initio molecular orbital calculation in such systems. A clear positive correlation was found between the C 2s and C 2pz populations and the negative muon capture ratio A (C/Cl), suggesting the mesomolecular process in the initial stage of muon capture. (orig.)

Numerical simulation for the influence of laser-induced plasmas addition on air mass capture of hypersonic inlet

Science.gov (United States)

Zhao, Wei; Dou, Zhiguo; Li, Qian

2012-03-01

The theory of laser-induced plasmas addition to hypersonic airflow off a vehicle to increase air mass capture and improve the performance of hypersonic inlets at Mach numbers below the design value is explored. For hypersonic vehicles, when flying at mach numbers lower than the design one, we can increase the mass capture ratio of inlet through laser-induced plasmas injection to the hypersonic flow upstream of cowl lip to form a virtual cowl. Based on the theory, the model of interaction between laser-induced plasmas and hypersonic flow was established. The influence on the effect of increasing mass capture ratio was studied at different positions of laser-induced plasmas region for the external compression hypersonic inlet at Mach 5 while the design value is 6, the power of plasmas was in the range of 1-8mJ. The main results are as follows: 1. the best location of the plasma addition region is near the intersection of the nose shock of the vehicle with the continuation of the cowl line, and slightly below that line. In that case, the shock generated by the heating is close to the shock that is a reflection of the vehicle nose shock off the imaginary solid surface-extension of the cowl. 2. Plasma addition does increase mass capture, and the effect becomes stronger as more energy is added, the peak value appeared when the power of plasma was about 4mJ, when the plasma energy continues to get stronger, the mass capture will decline slowly.

Single-electron capture for 2-8 keV incident energy and direct scattering at 6 keV in He[sup 2+]-He collisions

Energy Technology Data Exchange (ETDEWEB)

Bordenave-Montesquieu, D.; Dagnac, R. (Toulouse-3 Univ., 31 (France). Centre de Physique Atomique)

1992-06-14

We studied the single-electron capture as well as the direct processes occurring when a He[sup 2+] ion is scattered by a He target. Doubly differential cross sections were measured for single-electron capture with a collision energy ranging from 2 to 8 keV and a scattering angle varying from 10' to 3[sup o]30' (laboratory frame). Single-electron capture into excited states of He[sup +] was found to be the dominant process, confirming a previous experimental study. Elastic scattering and ionization differential cross sections were measured for E = 6 keV. (Author).

Correlation effects on double electron capture in highly-charged, low-energy ion-atom collisions

International Nuclear Information System (INIS)

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

1987-01-01

The method of zero-degree Auger electron spectroscopy has been used to study two-electron excited states populated in slow double capture collisions of highly charged ions with He and H 2 . The focus of this study is on production of autoionization electrons originating from the non-equivalent 1s 2 2pnl electron configurations in comparison with electron production resulting from the Auger decay of (near) equivalent 1s 2 nln'l' (with n∼n') configurations. It is shown that production of non-equivalent electron configurations is significant and involves electron-electron correlation effects whose analysis leads beyond the independent-particle model. Recent results that include a measurement at non-zero angles are presented to illustrate the angular dependence of electron emission from non-equivalent electron configurations, as well as the dependence on projectile charge state and target species. Comparison of high resolution scans over two lines of the 1s 2 2pnl sequence for the O 6+ + He system with accurate transition energy calculations shows preferential population of high angular momentum substation

Electron capture in low- and intermediate-energy collisions between completely stripped light ions and metastable H(2s) targets

International Nuclear Information System (INIS)

Blanco, S.A.; Falcon, C.A.; Reinhold, C.O.; Casaubon, J.I.; Piacentini, R.D.

1987-01-01

Total cross sections for electron capture from H(2s) targets by He 2+ ions have been computed in the impact velocity range 0.05-0.5 au. Calculations were performed using a molecular close-coupling approach with inclusion of electron translation factors. A ten-state molecular basis set was considered. A comparison is made with Landau-Zener results for the same system. Intermediate projectile energy classical Monte Carlo capture cross sections are also presented for H + , He 2+ , Li 3+ and C 6+ projectiles. (author)

Light- induced electron transfer and ATP synthesis in a carotene synthesizing insect

Science.gov (United States)

Valmalette, Jean Christophe; Dombrovsky, Aviv; Brat, Pierre; Mertz, Christian; Capovilla, Maria; Robichon, Alain

2012-08-01

A singular adaptive phenotype of a parthenogenetic insect species (Acyrthosiphon pisum) was selected in cold conditions and is characterized by a remarkable apparition of a greenish colour. The aphid pigments involve carotenoid genes well defined in chloroplasts and cyanobacteria and amazingly present in the aphid genome, likely by lateral transfer during evolution. The abundant carotenoid synthesis in aphids suggests strongly that a major and unknown physiological role is related to these compounds beyond their canonical anti-oxidant properties. We report here that the capture of light energy in living aphids results in the photo induced electron transfer from excited chromophores to acceptor molecules. The redox potentials of molecules involved in this process would be compatible with the reduction of the NAD+ coenzyme. This appears as an archaic photosynthetic system consisting of photo-emitted electrons that are in fine funnelled into the mitochondrial reducing power in order to synthesize ATP molecules.

Angular distributions of projectiles following electron capture from C60 by 2.5-keV Ar8+

International Nuclear Information System (INIS)

Walch, B.; Thumm, U.; Stoeckli, M.; Cocke, C.L.; Klawikowski, S.

1998-01-01

Experimental measurements of the projectile angular distributions for 2.5-keV Ar 8+ ions capturing one to five electrons from a gas-phase C 60 target are presented. The number of captured electrons was determined by demanding a coincidence between the scattered projectile and a charge-state-analyzed intact C 60 recoil ion. The results are compared to calculations based on a dynamical classical overbarrier model. Good agreement is obtained only if the influence on the projectile trajectory by the large polarizability of the C 60 target is taken into account, thereby making the collective dielectric response of the cluster target observable in a scattering experiment. copyright 1998 The American Physical Society

L-subshell resolved photon angular distribution of radiative electron capture into He-like uranium

International Nuclear Information System (INIS)

Stoehlker, T.; Geissel, H.; Irnich, H.; Kandler, T.; Kozhuharov, C.; Mokler, P.H.; Muenzenberg, G.; Nickel, F.; Scheidenberger, C.; Suzuki, T.; Kucharski, M.; Stachura, Z.; Kriessbach, A.; Shirai, T.

1994-08-01

The photon angular distributions for radiative electron capture (REC) into the j=1/2 and j=3/2 L-subshell levels were measured and calculated for U 90+ →C collisions at 89 MeV/u. The experiment provides the first study of the photon angular distribution of REC into a projectile p-state (j=3/2) which was found to exhibit a slight backward peaking in the laboratory frame. For radiative capture to the j=1/2 states the measured angular distribution deviates considerably from symmetry around 90 . The results demonstrate that the usual sin 2 θ lab distribution is not valid in the high-Z regime. (orig.)

Liquid scintillation counting efficiency in three photomultiplier systems. Pure electron capture

International Nuclear Information System (INIS)

Los Arcos, J. M.; Grau Carles, A.; Grau Malonda, A.

1990-01-01

The tables of counting efficiency as a function of the figure of merit for a liquid scintillation counting system working with three phototubes are presented. The evaluation has been carried out for a Toluene-based scintillator with 5, 10 and 15 ml column, and 19 different radionuclides decaying by pure electron capture: 37Ar 41Ca, 49V, 53 Mn, 55Fe, 59Ni, 68Ge 7iGe, 82Sr, 97Tc, 118Te, 131CS, 137La, 140Ca, 157Tb, 165Er, 193Pt, 194Hg, 205Pb. (Author) 22 refs

Electron-beam induced conduction in some polymers

International Nuclear Information System (INIS)

Suzuoki, Yasuo; Mizutani, Teruyoshi; Ieda, Masayuki

1976-01-01

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

Radioactivity induced by neutrons: Enrico Fermi and a thermodynamic approach to radiative capture

Science.gov (United States)

De Gregorio, Alberto

2006-07-01

When Fermi learned that slow neutrons are much more effective than fast ones in inducing radioactivity, he explained this phenomenon by mentioning the well-known scattering cross section between neutrons and protons. At this early stage, he did not refer to the capture cross section by target nuclei. At the same time a thermodynamic approach to neutron-proton capture was being discussed by physicists: neutron capture was interpretated as the reverse of deuteron photodissociation and detailed balance among neutrons, protons, deuterons, and radiation was invoked. This thermodynamic approach might underlie Fermi's early explanation of the great efficiency of slow neutrons. Fermi repeatedly used a thermodynamic approach that had been used in describing some of the physical properties of conductors by Richardson and had been influential in Fermi's youth.

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

Science.gov (United States)

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

Comparison of electronic data capture (EDC with the standard data capture method for clinical trial data.

Directory of Open Access Journals (Sweden)

Brigitte Walther

Full Text Available 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

Identification and systematical studies of the electron-capture delayed fission (ECDF) in the lead region

CERN Multimedia

Pauwels, D B; Lane, J

2008-01-01

In our recent experiment (March 2007) at the velocity filter SHIP(GSI) we observed the electron-capture delayed fission of the odd-odd isotope $^{194}$At. This is the first unambiguous identification of this phenomenon in the very neutron-deficient nuclei in the vicinity of the proton shell closure at Z=82. In addition, the total kinetic energy (TKE) for the daughter nuclide $^{194}$Po was measured, despite the fact that this isotope does not decay via spontaneous fission. Semi-empirical analysis of the electron-capture Q$_{EC}$ values and fission barriers B$_{f}$ shows that a relatively broad island of ECDF must exist in this region of the Nuclide Chart, with some of the nuclei having unusually high ECDF probabilities. Therefore, this Proposal is intended to initiate the systematic identification and study of $\\beta$-delayed fission at ISOLDE in the very neutron-deficient lead region. Our aim is to provide unique low-energy fission data (e.g. probabilities, TKE release, fission barriers and their isospin dep...

Measurement of K-electron capture probability in the decay of [sup 87]Y

Energy Technology Data Exchange (ETDEWEB)

Prasad, N.V.S.V.; Murty, G.S.K.; Rao, M.V.S.C.; Sastry, D.L. (Andhra Univ., Visakhapatnam (India). Labs. for Nuclear Research); Chintalapudi, S.N. (Inter University Consortium for DAE Facilities, Calcutta (India))

1993-04-01

The K-electron capture probability for the 1/2[sup -] to 3/2[sup -]transition in the decay of [sup 87]Y to the 873.0 keV level in the daughter [sup 87]Sr was measured for the first time using an x-[gamma] summing method. The experimental P[sub K] value was found to be 0.911 [+-] 0.047, in agreement with the theoretical value of 0.878. (author).

Electron capture, electron loss, and deexcitation of fast H(2 2S) and H(1 2S) atoms in collisions with molecular hydrogen and inert gases

International Nuclear Information System (INIS)

Roussel, F.; Pradel, P.; Spiess, G.

1977-01-01

Collisions of ground-state (1 2 S) and metastable (2 2 S) hydrogen atoms with rare gases and molecular hydrogen have been studied in the energy range 0.5--3.0 keV. For an acceptance angle of 55 mrad, the electron loss and the electron-capture cross sections of both H(1 2 S) and H(2 2 S) have been measured and compared with previous experimental values. The deexcitation cross section for H(2 2 S) has been deduced with the help of previously measured total-quenching cross sections for H(2 2 S). The ratio of the electron-capture cross sections for H(2 2 S) relative to H(1 2 S) is found to be very large for argon at low energies. The effects of large-angle scattering and of highly excited states of H are discussed

Second-order symmetric eikonal approximation for electron capture at high energies

Energy Technology Data Exchange (ETDEWEB)

Deco, G R; Rivarola, R D [Rosario Univ. Nacional (Argentina). Dept. de Fisica

1985-06-14

A symmetric eikonal approximation for electron capture in ion-atom collisions at high energies has been developed within the Dodd and Greider (1966, Phys. Rev. 146 675) formalism. Implicit intermediate states are included through the choice of distorted initial and final wavefunctions. Explicit intermediate state are considered by the introduction of a free-particle Green's function G/sup +//sub 0/. The model is applied for the resonant charge exchange in H/sup +/+H(1s) collisions. Also, the characteristic dip of the continuum distorted-wave model is analysed when higher orders are included at 'realistic' high energies.

Electron irradiation-induced defects in {beta}-SiC

Energy Technology Data Exchange (ETDEWEB)

Oshima, Ryuichiro [Osaka Prefectural Univ., Sakai (Japan). Reseach Inst. for Advanced Science and Technology

1996-04-01

To add information of point defects in cubic crystal SiC, polycrystal {beta}-SiC on the market was used as sample and irradiated by neutron and electron. In situ observation of neutron and electron irradiation-induced defects in {beta}-SiC were carried out by ultra high-voltage electronic microscope (UHVEM) and ordinary electronic microscope. The obtained results show that the electron irradiation-induced secondary defects are micro defects less than 20 nm at about 1273K, the density of defects is from 2x10{sup 17} to 1x10{sup 18}/cc, the secondary defects may be hole type at high temperature and the preexistant defects control nuclear formation of irradiation-induced defects, effective sink. (S.Y.)

A new magnetic spectrometer for the investigation of the internal conversion electron in capture reaction

International Nuclear Information System (INIS)

Suarez, A.A.

1978-01-01

Planning, development and manufacture of a new beta spectrometer for the investigation of the internal conversion electrons, from 0,02 to 10 MeV, emitted during the radioative capture process of the thermal neutrons. The resolution on the base of resolution curve is about 1,5 X 10 sup(-3) [pt

Experimental study of K-electron capture probability in the decay of {sup 111}In

Energy Technology Data Exchange (ETDEWEB)

Mishra, N.R.; Kalyani, V.D.M.L.; Maldhusudhana Rao, P.V.; Vara Prasad, N.V.; Chandrasekhar Rao, M.V.S.; Satyanarayana, G.; Sastry, D.L. [Visakhapatnam, Andhra Univ. (India). Swami Jnanananda Lab. for Nuclear Research; Chintalapudi, S.N. [Calcutt, Inter-Univ. Consortium for DAEW Facilities (India)

1998-03-01

The K-electron capture probability in the decay of {sup 111}In to the 416.64 keV level of the daughter nucleus {sup 111}Cd was measured to be 0.853 {+-}0.037 in agreement with the theoretical value 0.865. The experimental value is seen to be consistent with the mass prediction of the relationship due to Wapstra and Bos.

Evidence for correlated double-electron capture in slow collisions of multicharged ions with He and H2

International Nuclear Information System (INIS)

Meyer, F.W.; Havener, C.C.; Phaneuf, R.A.; Swenson, J.K.; Shafroth, S.M.; Stolterfoht, N.

1986-01-01

High resolution measurements of the production of L 1 L 23 M Coster-Kronig and LMM-Auger electrons in slow collisions of C 4+ , N 5+ , O 6+ , and 0 7+ with He and H 2 have been performed, using the method of 0 0 Auger spectroscopy. For the latter three projectiles, strong Coster Kronig lines are observed, which are attributed to the configurations (core)2pnl, produced by double-electron capture. It is argued that production of these nonequivalent electron configurations must involve electron-electron correlation. From a comparison of the production cross sections for these Coster-Kronig electrons and the LMM-Auger electrons, it is further argued the correlation plays a significant role in two-electron transfer processes. 7 refs., 5 figs

Measurement on K-electron capture probability in the decay of 97Ru

International Nuclear Information System (INIS)

Kalayani, V.D.M.L.; Vara Prasad, N.V.S.; Chandrasekhar Rao, M.V.S.; Satyanarayana, G.; Sastry, D.L.; Chintalapudi, S.N.

1999-01-01

The K-electron capture probabilities of two strong allowed transitions 5/2 + →5/2 + and 5/2 + →7/2 + were measured in the decay of 97 Ru employing the X-γ internal summing technique. The two P K experimental values were found to be 0.884±0.046 and 0.886±0.018 in agreement with the theoretical values 0.878 and 0.878, respectively. The theoretical values are seen to be insensitive for Q EC values above 200 keV

Electron capture and excitation in collisions of O+(4S,2D,2P) with H2 molecules

International Nuclear Information System (INIS)

Pichl, Lukas; Li Yan; Liebermann, Heinz-Peter; Buenker, Robert J.; Kimura, Mineo

2004-01-01

Using an electronic-state close-coupling method, we treated the electron capture and excitation processes of O + ions both in ground state O + ( 4 S) and metastable states O +* ( 2 D) and O +* ( 2 P) in collisions with the H 2 molecule. In the ground-state projectile energy region considered (from 50 eV/amu to 10 keV/amu), the experimental data vary by orders of magnitude: our results smoothly connect to the data by Flesch and Ng [J. Chem. Phys. 94, 2372 (1991)] and Xu et al. [J. Phys. B 23, 1235 (1990)] at low energy and agree with Phaneuf et al. [Phys. Rev. A 17, 534 (1978)] in the high-energy region. The present values differ from Sieglaff et al. [Phys. Rev. A 59, 3538 (1999)] and Nutt et al. [J. Phys. B 12, L157 (1979)], especially in the energy region below 1 keV/amu. We provide the first calculated state-resolved cross sections of electron capture and target-projectile electronic excitations for the O + ( 4 S, 2 D, 2 P)-H 2 collision system

COINCIDENCES BETWEEN ELECTRONS AND TARGET IONS TO IDENTIFY CAPTURE CHANNELS IN COLLISIONS OF MULTIPLY CHARGED IONS ON GAS TARGETS

NARCIS (Netherlands)

POSTHUMUS, JH; MORGENSTERN, R

1992-01-01

We have investigated multielectron capture processes in collisions of Ar9+ on Ar by measuring the resulting Auger electrons in coincidence with charge-state-analyzed target ions. In this way it was possible to reconstruct partial electron energy spectra, each corresponding to a particular number of

Radiative electron capture studied in relativistic heavy-ion--atom collisions

International Nuclear Information System (INIS)

Stoehlker, T.; Kozhuharov, C.; Mokler, P.H.; Warczak, A.; Bosch, F.; Geissel, H.; Moshammer, R.; Scheidenberger, C.; Eichler, J.; Ichihara, A.; Shirai, T.; Stachura, Z.; Rymuza, P.

1995-01-01

The process of radiative electron capture (REC) in relativistic collisions of high-Z ions with low-Z gaseous and solid targets is studied experimentally and theoretically. The observed x-ray spectra are analyzed with respect to photon angular distributions as well as to total K-REC cross sections. The experimental results for angle-differential cross sections are well reproduced by exact relativistic calculations which yield significant deviations from standard sin 2 θ distributions. Total cross sections for K-REC are shown to follow a simple scaling rule obtained from exact relativistic calculations as well as from a nonrelativistic dipole approximation. The agreement between these different theoretical approaches must be regarded as fortuitous, but it lends support to the use of the nonrelativistic approach for practical purposes

Physics Reach with a Monochromatic Neutrino Beam from Electron Capture

CERN Document Server

Bernabeu, J.; Espinoza, C.; Lindroos, M.

2005-01-01

Neutrino oscillation experiments from different sources have demonstrated non-vanishing neutrino masses and flavour mixings. The next experiments have to address the determination of the connecting mixing U(e3) and the existence of the CP violating phase. Whereas U(e3) measures the strength of the oscillation probability in appearance experiments, the CP phase acts as a phase-shift in the interference pattern. Here we propose to separate these two parameters by energy dependence, using the novel idea of a monochromatic neutrino beam facility based on the acceleration of ions that decay fast through electron capture. Fine tuning of the boosted neutrino energy allows precision measurements able to open a window for the discovery of CP violation, even for a mixing as small as 1 degree

Comparison of quantification methods for the analysis of polychlorinated alkanes using electron capture negative ionization mass spectrometry.

NARCIS (Netherlands)

Rusina, T.; Korytar, P.; de Boer, J.

2011-01-01

Four quantification methods for short-chain chlorinated paraffins (SCCPs) or polychlorinated alkanes (PCAs) using gas chromatography electron capture negative ionisation low resolution mass spectrometry (GC-ECNI-LRMS) were investigated. The method based on visual comparison of congener group

Comparison of quantification methods for the analysis of polychlorinated alkanes using electron capture negative ionisation mass spectrometry

NARCIS (Netherlands)

Rusina, T.; Korytar, P.; Boer, de J.

2011-01-01

Four quantification methods for short-chain chlorinated paraffins (SCCPs) or polychlorinated alkanes (PCAs) using gas chromatography electron capture negative ionisation low resolution mass spectrometry (GC-ECNI-LRMS) were investigated. The method based on visual comparison of congener group

Dipole and Coulomb forces in electron capture dissociation and electron transfer dissociation mass spectroscopy.

Science.gov (United States)

Świerszcz, Iwona; Skurski, Piotr; Simons, Jack

2012-02-23

Ab initio electronic structure calculations were performed on a doubly charged polypeptide model H(+)-Lys(Ala)(19)-CO-CH(NH(2))-CH(2)-SS-CH(2)-(NH(2))CH-CO-(Ala)(19)-Lys-H(+) consisting of a C-terminal protonated Lys followed by a 19-Ala α-helix with a 20th Ala-like unit whose side chain is linked by a disulfide bond to a corresponding Ala-like unit connected to a second 19-Ala α-helix terminated by a second C-terminal-protonated Lys. The Coulomb potentials arising from the two charged Lys residues and dipole potentials arising from the two oppositely directed 72 D dipoles of the α-helices act to stabilize the SS bond's σ* orbital. The Coulomb potentials provide stabilization of 1 eV, while the two large dipoles generate an additional 4 eV. Such stabilization allows the SS σ* orbital to attach an electron and thereby generate disulfide bond cleavage products. Although calculations are performed only on SS bond cleavage, discussion of N-C(α) bond cleavage caused by electron attachment to amide π* orbitals is also presented. The magnitudes of the stabilization energies as well as the fact that they arise from Coulomb and dipole potentials are supported by results on a small model system consisting of a H(3)C-SS-CH(3) molecule with positive and negative fractional point charges to its left and right designed to represent (i) two positive charges ca. 32 Å distant (i.e., the two charged Lys sites of the peptide model) and (ii) two 72 D dipoles (i.e., the two α-helices). Earlier workers suggested that internal dipole forces in polypeptides could act to guide incoming free electrons (i.e., in electron capture dissociation (ECD)) toward the positive end of the dipole and thus affect the branching ratios for cleaving various bonds. Those workers argued that, because of the huge mass difference between an anion donor and a free electron, internal dipole forces would have a far smaller influence over the trajectory of a donor (i.e., in electron transfer dissociation

Radiative electron capture studied in relativistic heavy-ion atom collisions

International Nuclear Information System (INIS)

Stoehlker, T.; Kozhuharov, C.; Mokler, P.H.; Warczak, A.; Bosch, F.; Geissel, H.; Moshammer, R.; Scheidenberger, C.; Eichler, J.; Shirai, T.; Stachura, Z.; Rymuza, P.

1994-08-01

The process of Radiative Electron Capture (REC) in relativistic collisions of high-Z ions with low-Z gaseous and solid targets is studied experimentally and theoretically. The observed X-ray spectra are analysed with respect to photon angular distributions as well as to total K-REC cross sections. The experimental results for angle-differential cross sections are well-reproduced by exact relativistic calculations which yield significant deviations from standard sin 2 θ distributions. Total cross sections for K-REC are shown to follow a simple scaling rule obtained from exact relativistic calculations as well as from a non-relativistic dipole approximation. The agreement between these different theoretical approaches must be regarded as fortuitous, but it lends support to the use of the non-relativistic approach for practical purposes. (orig.)

Precision electron-capture energy in {sup 202}Pb and its relevance for neutrino mass determination

Energy Technology Data Exchange (ETDEWEB)

Welker, A. [CERN, Geneva (Switzerland); Technische Universitaet Dresden, Dresden (Germany); Filianin, P. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Althubiti, N.A.S. [The University of Manchester, School of Physics and Astronomy, Manchester (United Kingdom); Atanasov, D.; Blaum, K.; Eliseev, S.; Kreim, S. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Cocolios, T.E. [The University of Manchester, School of Physics and Astronomy, Manchester (United Kingdom); KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven (Belgium); Herfurth, F.; Neidherr, D. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Lunney, D. [CSNSM-IN2P3-CNRS, Universite Paris-Sud, Orsay (France); Manea, V. [CERN, Geneva (Switzerland); Novikov, Yu. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Physics Faculty, St. Petersburg State University (Russian Federation); Rosenbusch, M.; Schweikhard, L.; Wienholtz, F. [Ernst-Moritz-Arndt-Universitaet, Institut fuer Physik, Greifswald (Germany); Wolf, R.N. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); The University of Sydney, ARC Centre of Excellence for Engineered Quantum Systems, Sydney (Australia); Zuber, K. [Technische Universitaet Dresden, Dresden (Germany)

2017-07-15

Within the framework of an extensive programme devoted to the search for alternative candidates for the neutrino mass determination, the atomic mass difference between {sup 202}Pb and {sup 202}Tl has been measured with the Penning trap mass spectrometer ISOLTRAP at the ISOLDE facility at CERN. The obtained value Q{sub EC} = 38.8(43) keV is three times more precise than the AME2012 value. While it will probably not lead to a replacement of {sup 163}Ho in modern experiments on the determination of the electron-neutrino mass, the electron capture in {sup 202}Pb would however allow a determination of the electron-neutrino mass on the few-eV level using a cryogenic micro-calorimeter. (orig.)

Electron-capture Rates for pf-shell Nuclei in Stellar Environments and Nucleosynthesis

Science.gov (United States)

Suzuki, Toshio; Honma, Michio; Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Hidakai, Jun; Otsuka, Takaharu

Gamow-Teller strengths in pf-shell nuclei obtained by a new shell-model Hamltonian, GXPF1J, are used to evaluate electron-capture rates in pf-shell nuclei at stellar environments. The nuclear weak rates with GXPF1J, which are generally smaller than previous evaluations for proton-rich nuclei, are applied to nucleosynthesis in type Ia supernova explosions. The updated rates are found to lead to less production of neutron-rich nuclei such as 58Ni and 54Cr, thus toward a solution of the problem of over-production of neutron-rich isotopes of iron-group nuclei compared to the solar abundance.

Resonant Electron capture for be-like ions with K- and L- shell excitations

International Nuclear Information System (INIS)

Hanafy, H.

2005-01-01

Resonant electron capture in electron-ion collisions is known as dielectronic recombination (DR). It was proved that, DR dominants usually over radiative recombination (RR) at high energy. Since 1980's, DR is considered a very important process in thermal plasma. The DR is an effective process in self-cooling and ionization balance as well as plasma modeling. Experimental works are still carried out to understand the trends of DR process. In the present work, DR cross sections are calculated for Be-like ions with K- and L- shell excitations. It is found that, DR cross sections increase as the effective charge (Zeff) increases for both types of excitations. DR rates coefficient in case of L-shell excitation is found to be five times larger than that of K-shell excitation

Analysis of neonicotinoids by gas chromatography coupled to nuclide 63Ni - Electron Capture Detector - GC/ECD

International Nuclear Information System (INIS)

Amaral, Priscila O.; Leao, Claudio; Redigolo, Marcelo M.; Crepaldi, Caike; Bustillos, Oscar V.

2015-01-01

Recently, several reports have been published discussing reduction in bee population which polymerizes cultures around the world this phenomenon is known as Colony Collapse Disorder (CCD). The phenomenon describes the lack of worker honeybees in the colony despite having pups and food. The causes of this problem are unknown but there are studies that claim that reduction of population of bees is linked to poisoning through insecticides specifically neonicotinoids. Among this type of pesticide are imidacloprid (C 9 H 10 ClN 5 O 2 ), clothianidin (C 6 H 8 ClN 5 O 2 S) and thiamethoxam (C 8 H 10 ClN 5 O 3 S). This paper presents the analysis of neonicotinoids - clothianidin, imidacloprid and thiamethoxam - by the technique of gas chromatography coupled to nuclide 63 Ni electron capture detector (GC/ECD). The electron capture detector (ECD) is a gas chromatography detector that has been used for the detection of organic halogens, nitriles, nitrates and organometallic compounds. The ECD detector ionizes the analytes by the beta particles from the nuclide sources 63 Ni within carrier gas N 2 . The electrons produced in this process are collected and create a current that are amplified and generates a chromatographic peak. Methodology and details of the analysis are present in this work. (author)

Relative K-electron capture probabilities in the decay of 99Rh

International Nuclear Information System (INIS)

Mishra, N.R.; Chandrasekhar Rao, M.V.S.; Satyanarayana, G.; Sastry, D.L.; Chintalapudi, S.N.

2000-01-01

The relative K-electron capture probabilities (P K ) to the 1383.23, 896.98, 618.09, 442.78 and 322.43 keV levels in 99 Ru in the decay of 99 Rh are measured employing the X-γ internal sum-coincidence technique. The measured values P K 1383.23=0.851±0.066, P K 896.98=0.834±0.061, P K 618.09=0.870±0.01, P K 442.78=0.882±0.035 and P K 322.43=0.852±0.061 are found to be in good agreement with the theoretical values. The dependence of P K on EC transition energy is discussed. (author)

Influence of the Coulomb interaction in the final state on the cross section of single-electron capture by fast ions

International Nuclear Information System (INIS)

Novikov, N.V.; Teplova, Ya.A.

2011-01-01

It is shown that the Coulomb interaction of ions in the final state must be taken into account in the estimation of the cross section of electron capture by fast ions. The cross section of electron capture decreases considerably, and the dependence of the cross section on the collision energy becomes close to the experimental one if the interaction of charged particles after collision is taken into account. -- Highlights: → Coulomb interaction of ions in the final state must be taken into account. → This interaction leads to a considerable decrease in the cross section. → The dependence on energy close to the experimental one.

Electron-beam-induced-current and active secondary-electron voltage-contrast with aberration-corrected electron probes

Energy Technology Data Exchange (ETDEWEB)

Han, Myung-Geun, E-mail: mghan@bnl.gov [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Garlow, Joseph A. [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Materials Science and Engineering Department, Stony Brook University, Stony Brook, NY 11794 (United States); Marshall, Matthew S.J.; Tiano, Amanda L. [Department of Chemistry, Stony Brook University, Stony Brook, NY 11974 (United States); Wong, Stanislaus S. [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Department of Chemistry, Stony Brook University, Stony Brook, NY 11974 (United States); Cheong, Sang-Wook [Department of Physics and Astronomy, Rutgers Center for Emergent Materials, Rutgers University, Piscataway, NJ 08854 (United States); Walker, Frederick J.; Ahn, Charles H. [Department of Applied Physics and Center for Research on Interface Structures and Phenomena, Yale University, New Haven, CT 06520 (United States); Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT 06520 (United States); Zhu, Yimei [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States)

2017-05-15

Highlights: • Electron-beam-induced-current (EBIC) and active secondary-electron voltage-contrast (SE-VC) are demonstrated in STEM mode combined with in situ electrical biasing in a TEM. • Electrostatic potential maps in ferroelectric thin films, multiferroic nanowires, and single crystals obtained by off-axis electron holography were compared with EBIC and SE-VC data. • Simultaneous EBIC and active SE-VC performed with atomic resolution STEM are demonstrated. - Abstract: The ability to map out electrostatic potentials in materials is critical for the development and the design of nanoscale electronic and spintronic devices in modern industry. Electron holography has been an important tool for revealing electric and magnetic field distributions in microelectronics and magnetic-based memory devices, however, its utility is hindered by several practical constraints, such as charging artifacts and limitations in sensitivity and in field of view. In this article, we report electron-beam-induced-current (EBIC) and secondary-electron voltage-contrast (SE-VC) with an aberration-corrected electron probe in a transmission electron microscope (TEM), as complementary techniques to electron holography, to measure electric fields and surface potentials, respectively. These two techniques were applied to ferroelectric thin films, multiferroic nanowires, and single crystals. Electrostatic potential maps obtained by off-axis electron holography were compared with EBIC and SE-VC to show that these techniques can be used as a complementary approach to validate quantitative results obtained from electron holography analysis.

Single electron capture measurements in collisions of K{sup +} on N{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Alarcón, F.B. [Laboratorio de Espectroscopia, Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apartado Postal 48-3, 62210 Cuernavaca, Morelos (Mexico); Fuentes, B.E., E-mail: beatriz.fuentes@ciencias.unam.mx [Facultad de Ciencias, Universidad Nacional Autónoma de México, Circuito Exterior, Cd. Universitaria, 04510 México D.F. (Mexico); Martínez, H. [Laboratorio de Espectroscopia, Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apartado Postal 48-3, 62210 Cuernavaca, Morelos (Mexico); Yousif, F.B. [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad #1000, Col. Chamilpa, C.P. 62210, Cuernavaca, Morelos (Mexico)

2014-08-01

Absolute total charge transfer cross sections have been measured for K{sup +}–N{sub 2} 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.

Probing Protein Structure and Folding in the Gas Phase by Electron Capture Dissociation

Science.gov (United States)

Schennach, Moritz; Breuker, Kathrin

2015-07-01

The established methods for the study of atom-detailed protein structure in the condensed phases, X-ray crystallography and nuclear magnetic resonance spectroscopy, have recently been complemented by new techniques by which nearly or fully desolvated protein structures are probed in gas-phase experiments. Electron capture dissociation (ECD) is unique among these as it provides residue-specific, although indirect, structural information. In this Critical Insight article, we discuss the development of ECD for the structural probing of gaseous protein ions, its potential, and limitations.

Electron transport effects in ion induced electron emission

Energy Technology Data Exchange (ETDEWEB)

Dubus, A. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. FD Roosevelt, B-1050 Brussels (Belgium)]. E-mail: adubus@ulb.ac.be; Pauly, N. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. FD Roosevelt, B-1050 Brussels (Belgium); Roesler, M. [Karl-Pokern-Str. 12, D-12587 Berlin (Germany)

2007-03-15

Ion induced electron emission (IIEE) is usually described as a three-step process, i.e. electron excitation by the incident projectile, electron transport (and multiplication) and electron escape through the potential barrier at the surface. In many cases, the first step of the process has been carefully described. The second step of the process, i.e. electron transport and multiplication, has often been treated in a very rough way, a simple decreasing exponential law being sometimes used. It is precisely the aim of the present work to show the importance of a correct description of electron transport and multiplication in a theoretical calculation of IIEE. A short overview of the electron transport models developed for IIEE is given in this work. The so-called 'Infinite medium slowing-down model' often used in recent works is evaluated by means of Monte Carlo simulations. In particular, the importance of considering correctly the semi-infinite character of the medium and the boundary condition at the vacuum-medium interface is discussed. Quantities like the electron escape depth are also briefly discussed. This evaluation has been performed in the particular case of protons (25keV

Electron-beam-induced conduction in dielectrics

Energy Technology Data Exchange (ETDEWEB)

Acris, F C; Davies, P M; Lewis, T J [University Coll. of North Wales, Bangor (UK). School of Electronic Engineering Science

1976-03-14

A model for the enhanced conduction induced in dielectric films under electron bombardment while electrically stressed is discussed. It is assumed that the beam produces a virtual electrode at the end of its range in the dielectric and, as a consequence, the induced conduction is shown to depend on the properties of that part of the dielectric beyond the range of the beam. This model has also been discussed recently by Nunes de Oliviera and Gross. In the present treatment, it is shown how the model permits investigation of beam scattering and carrier generation and recombination processes. Experiments on electron-bombardment-induced conduction of thin (72 to 360 nm) films of anodic tantalum oxide are reported and it is shown that the theoretical model provides a very satisfactory explanation of all features of the results including the apparent threshold energy for enhanced conduction.

Hexagonal boron nitride and graphene in-plane heterostructures: An experimentally feasible approach to charge-induced switchable CO{sub 2} capture

Energy Technology Data Exchange (ETDEWEB)

Tan, Xin; Tahini, Hassan A.; Smith, Sean C., E-mail: sean.smith@unsw.edu.au

2016-10-20

Hexagonal boron nitride (h-BN) has been proposed as a sorbent material for charge-induced switchable CO{sub 2} capture. However, h-BN is a wide-gap semiconductor, hindering injection of the requisite charge. Here, we employ first-principle calculations to support the proposal that in-plane h-BN/graphene (P-BN/G) heterostructures, consisting of alternating strips of h-BN and graphene, may provide an experimentally feasible material platform for voltage-induced charging of h-BN strips to realize switchable CO{sub 2} capture. Our results show that a significant amount of injected negative charges are distributed onto h-BN strips of P-BN/G, such that CO{sub 2} capture/release can be simply controlled by switching on/off the charge states of P-BN/G system. At saturation CO{sub 2} capture coverage, the negatively charged P-BN/G heterostructures achieve CO{sub 2} capture capacities up to 2.27 × 10{sup 14} cm{sup −2}, which is twice that which can be achieved on stacked h-BN/graphene (S-BN/G) nanosheets.

Measurement on K-electron capture probability in the decay of {sup 97}Ru

Energy Technology Data Exchange (ETDEWEB)

Kalayani, V.D.M.L.; Vara Prasad, N.V.S.; Chandrasekhar Rao, M.V.S.; Satyanarayana, G.; Sastry, D.L. [Swami Jnanananda Laboratories for Nuclear Research, Andhra University, Visakhapatnam (India); Chintalapudi, S.N. [Inter University Consortium for DEA Facililities, Calcutta (India)

1999-08-01

The K-electron capture probabilities of two strong allowed transitions 5/2{sup +}{yields}5/2{sup +} and 5/2{sup +}{yields}7/2{sup +} were measured in the decay of {sup 97}Ru employing the X-{gamma} internal summing technique. The two P{sub K} experimental values were found to be 0.884{+-}0.046 and 0.886{+-}0.018 in agreement with the theoretical values 0.878 and 0.878, respectively. The theoretical values are seen to be insensitive for Q{sub EC} values above 200 keV.

Three-dimensional nanofabrication by electron-beam-induced deposition using 200-keV electrons in scanning transmission electron microscope

International Nuclear Information System (INIS)

Liu, Z.Q.; Mitsuishi, K.; Furuya, K.

2005-01-01

Attempts were made to fabricate three-dimensional nanostructures on and out of a substrate by electron-beam-induced deposition in a 200-kV scanning transmission electron microscope. Structures with parallel wires over the substrate surface were difficult to fabricate due to the direct deposition of wires on both top and bottom surfaces of the substrate. Within the penetration depth of the incident electron beam, nanotweezers were fabricated by moving the electron beam beyond different substrate layers. Combining the deposition of self-supporting wires and self-standing tips, complicated three-dimensional doll-like, flag-like, and gate-like nanostructures that extend out of the substrate were successfully fabricated with one-step or multi-step scans of the electron beam. Effects of coarsening, nucleation, and distortion during electron-beam-induced deposition are discussed. (orig.)

One-electron capture and target ionization in He+-neutral-atom collisions

International Nuclear Information System (INIS)

Shevelko, V.P.; Tolstikhina, I.Yu.; Kato, D.; Tawara, H.; Song, M-.Y.; Yoon, J-.S.

2009-12-01

One-electron capture and target-ionization cross sections in collisions of He + ions with neutral atoms: He + + A → He + A + and He + + A → He + + A + + e, A = H, He(1s 2 , 1s2s), Ne, Ar, Kr, Xe, are calculated and compared with available experimental data over the broad energy range E = 0.1 keV/u - 10 MeV/u of He + ions. The role of the metastable states of neutral helium atoms in such collisions, which are of importance in plasma physics applications, is briefly discussed. The recommended cross section data for these processes are presented in a closed analytical form (nine-order polynomials) which can be used for a plasma modeling and diagnostics. (author)

Shifts in electron capture to the continuum at low collision energies: Enhanced role of target postcollision interactions

International Nuclear Information System (INIS)

Shah, M. B.; McGrath, C.; Luna, H.; Crothers, D.S.F.; O'Rourke, S.F.C.; Gilbody, H.B.; Illescas, Clara; Riera, A.; Pons, B.

2003-01-01

Measurements of electron velocity distributions emitted at 0 deg. for collisions of 10- and 20-keV H + incident ions on H 2 and He show that the electron capture to the continuum cusp formation, which is still possible at these low impact energies, is shifted to lower momenta than its standard position (centered on the projectile velocity), as recently predicted. Classical trajectory Monte Carlo calculations reproduce the observations remarkably well, and indicate that a long-range residual interaction of the electron with the target ion after ionization is responsible for the shifts, which is a general effect that is enhanced at low nuclear velocities

Radiative electron capture into the K-, L-, and M-shell of decelerated, hydrogenic Ge projectiles

International Nuclear Information System (INIS)

Stoehlker, T.; Kozhuharov, C.; Livingston, A.E.; Mokler, P.H.; Stachura, Z.; Warczak, A.

1991-12-01

Radiative Electron Capture (REC) in 4 to 12 MeV/u Ge 31+ →H 2 collisions has been studied using an X-ray/particle coincidence technique. This technique allowed a systematic investigation of K-shell REC as well as a separation of REC into the projectile L- and M-shells. The cross sections are discussed within a general scaling picture based on the reduced projectile velocity. (orig.)

Reactions induced by low energy electrons in cryogenic films

International Nuclear Information System (INIS)

Bass, A.D.; Sanche, L.

2003-01-01

We review recent research on reactions (including dissociation) initiated by low-energy electron bombardment of monolayer and multilayer molecular solids at cryogenic temperatures. With incident electrons of energies below 20 eV, dissociation is observed by the electron stimulated desorption (ESD) of anions from target films and is attributed to the processes of dissociative electron attachment (DEA) and to dipolar dissociation. It is shown that DEA to condensed molecules is sensitive to environmental factors such as the identity of co-adsorbed species and film morphology. The effects of image-charge induced polarization on cross-sections for DEA to CH3Cl are also discussed. Taking as examples, the electron-induced production of CO within multilayer films of methanol and acetone, it is shown that the detection of electronic excited states by high resolution electron energy loss spectroscopy can be used to monitor electron beam damage. In particular, the incident energy dependence of the CO indicates that below 19 eV, dissociation proceeds via the decay of transient negative ions (TNI) into electronically excited dissociative states. The electron induced dissociation of biomolecular targets is also considered, taking as examples the ribose analog tetrahydrofuran and DNA bases adenine and thymine, cytosine and guanine. The ESD of anions from such films also show dissociation via the formation of TNI. In multilayer molecular solids, fragment species resulting from dissociation, may react with neighboring molecules, as is demonstrated in anion ESD measurements from films containing O 2 and various hydrocarbon molecules. X-ray photoelectron spectroscopy measurements reported for electron irradiated monolayers of H 2 O and CF 4 on a Si - H passivated surface further show that DEA is an important initial step in the electron-induced chemisorption of fragment species

Resonance enhancement of neutrinoless double electron capture

International Nuclear Information System (INIS)

Krivoruchenko, M.I.; Simkovic, Fedor; Frekers, Dieter; Faessler, Amand

2011-01-01

The process of neutrinoless double electron (0νECEC) capture is revisited for those cases where the two participating atoms are nearly degenerate in mass. The theoretical framework is the formalism of an oscillation of two atoms with different total lepton number (and parity), one of which can be in an excited state so that mass degeneracy is realized. In such a case and assuming light Majorana neutrinos, the two atoms will be in a mixed configuration with respect to the weak interaction. A resonant enhancement of transitions between such pairs of atoms will occur, which could be detected by the subsequent electromagnetic de-excitation of the excited state of the daughter atom and nucleus. Available data of atomic masses, as well as nuclear and atomic excitations are used to select the most likely candidates for the resonant transitions. Assuming an effective mass for the Majorana neutrino of 1 eV, some half-lives are predicted to be as low as 10 22 years in the unitary limit. It is argued that, in order to obtain more accurate predictions for the 0νECEC half-lives, precision mass measurements of the atoms involved are necessary, which can readily be accomplished by today's high precision Penning traps. Further advancements also require a better understanding of high-lying excited states of the final nuclei (i.e. excitation energy, angular momentum and parity) and the calculation of the nuclear matrix elements.

Determination of DDTs and PCBs by capillary gas chromatography and electron capture detection

International Nuclear Information System (INIS)

1988-01-01

This reference method deals with the determination of DDTs and PCBs in marine environmental samples using high resolution gas chromatography. Several other halogenated pesticides and other electron capturing organic compounds may be present in samples and many of these may also be determined by this method. Not all electron capturing residues will be resistant to all of the clean up procedures described here for the analysis of DTTs and PCBs. Therefore, additional information on the stability of some common pesticides using this methodology is also provided. The high separation power of open tubular (''capillary'') columns allows the identification and quantification of many compounds in the complex mixtures occurring in environmental samples. This manual provides information on the theoretical and practical aspects of the use of these high resolution columns for the analysis of DDTs and PCBs in environmental samples. The qualitative and quantitative method can be applied to any sample type (aerosol/vapour, water, particulates, biota, etc.) provided that suitable cleaned-up extracts dissolved in n-hexane are available for injection into the GC system. For example, methods for obtaining these cleaned-up sample extracts from marine organisms are described in detail in UNEP Reference Method no. 14 and for sediments in No. 17. The change in the field of application by analysing by capillary rather than packed columns may be less dramatic for DDTs. However, with the increased separation, the possibilities of inaccurate analysis resulting from overlap with interfering compounds is reduced. 7 refs, 1 fig., 3 tabs

Surface characterization by energy distribution measurements of secondary electrons and of ion-induced electrons

International Nuclear Information System (INIS)

Bauer, H.E.; Seiler, H.

1988-01-01

Instruments for surface microanalysis (e.g. scanning electron or ion microprobes, emission electron or ion microscopes) use the current of emitted secondary electrons or of emitted ion-induced electrons for imaging of the analysed surface. These currents, integrating over all energies of the emitted low energy electrons, are however, not well suited to surface analytical purposes. On the contrary, the energy distribution of these electrons is extremely surface-sensitive with respect to shape, size, width, most probable energy, and cut-off energy. The energy distribution measurements were performed with a cylindrical mirror analyser and converted into N(E), if necessary. Presented are energy spectra of electrons released by electrons and argon ions of some contaminated and sputter cleaned metals, the change of the secondary electron energy distribution from oxidized aluminium to clean aluminium, and the change of the cut-off energy due to work function change of oxidized aluminium, and of a silver layer on a platinum sample. The energy distribution of the secondary electrons often shows detailed structures, probably due to low-energy Auger electrons, and is broader than the energy distribution of ion-induced electrons of the same object point. (author)

Electron emission from solids induced by swift heavy ions

International Nuclear Information System (INIS)

Xiao Guoqing

2000-01-01

The recent progresses in experimental and theoretical studies of the collision between swift heavy ion and solids as well as electron emission induced by swift heavy ion in solids were briefly reviewed. Three models, Coulomb explosion, thermal spike and repulsive long-lived states, for interpreting the atomic displacements stimulated by the electronic energy loss were discussed. The experimental setup and methods for measuring the electron emission from solids were described. The signification deviation from a proportionality between total electron emission yields and electronic stopping power was found. Auger-electron and convoy-electron spectra are thought to be a probe for investigating the microscopic production mechanisms of the electronic irradiation-damage. Electron temperature and track potential at the center of nuclear tracks in C and polypropylene foils induced by 5 MeV/u heavy ions, which are related to the electronic excitation density in metals and insulators respectively, were extracted by measuring the high resolution electron spectra

Electron capture in collisions of ? with H and ? with C

Science.gov (United States)

Stancil, P. C.; Gu, J.-P.; Havener, C. C.; Krstic, P. S.; Schultz, D. R.; Kimura, M.; Zygelman, B.; Hirsch, G.; Buenker, R. J.; Bannister, M. E.

1998-08-01

A comprehensive theoretical and experimental study of electron capture in collisions of 0953-4075/31/16/017/img15 with H and 0953-4075/31/16/017/img16 with C extending over the energy range 0953-4075/31/16/017/img17 to 0953-4075/31/16/017/img18 is presented. A variety of theoretical approaches were used including those based on quantal molecular-orbital close-coupling (MOCC), multielectron hidden crossings (MEHC), quantal decay and classical trajectory Monte Carlo techniques. Radiative charge transfer cross sections were computed using the optical potential/distorted wave (OPDW) and fully quantal (FQ) approaches. The MOCC, OPDW and FQ calculations incorporated ab initio potentials, nonadiabatic coupling matrix elements and transition moments computed at the configuration-interaction level. Ab initio potential surfaces in the plane of complex internuclear distance were obtained for the MEHC calculations. Merged-beam measurements were performed between 0953-4075/31/16/017/img19 and 0953-4075/31/16/017/img20 for the 0953-4075/31/16/017/img21 collision system. Diagnostics of the 0953-4075/31/16/017/img15 beam with a crossed electron beam could find no presence of a 0953-4075/31/16/017/img15 metastable component. The current results, in conjunction with previous measurements, are used to deduce a set of recommended cross sections.

The boundary-corrected second Born (B2B) approximation: proton-hydrogen electron capture

International Nuclear Information System (INIS)

Dewangan, D.P.; Bransden, B.H.

1988-01-01

The probability amplitude for proton-hydrogen ground-state electron capture at 125 keV in the boundary-corrected second Born approximation has been evaluated numerically by retaining all significant bound and continuum hydrogenic intermediate states for which the orbital angular momentum l ≤ 3. The differential cross section is found to be in good agreement with the experimental data for scattering angles less than about 1 mrad in the centre of mass system. The value of the boundary-corrected second Born total cross section is similar to that obtained in the boundary-corrected first Born approximation. (author)

Population of Rydberg states by electron capture in fast-ion--atom collisions

International Nuclear Information System (INIS)

Burgdoerfer, J.; Dube, L.J.

1985-01-01

The l,m-substate distribution in low-lying Rydberg manifolds (nroughly-equal10) following electron capture H + +H(1s)→H(n)+H + is calculated at high velocities (v>1 a.u.) in the continuum-distorted-wave (CDW) approximation. The standard CDW approximation is modified to account for final-state Stark mixing of the Rydberg manifold in the exit channel using the post-collision-interaction model. The influence of multiple-scattering contributions is analyzed and comparison is made with sigma/sub l/m predicted by the Born approximation. We find that the double-scattering contribution, closely connected with the classical Thomas process, becomes visible in the CDW approximation at surprisingly low nonasymptotic velocities

Electron capture rates in stars studied with heavy ion charge exchange reactions

Science.gov (United States)

Bertulani, C. A.

2018-01-01

Indirect methods using nucleus-nucleus reactions at high energies (here, high energies mean ~ 50 MeV/nucleon and higher) are now routinely used to extract information of interest for nuclear astrophysics. This is of extreme relevance as many of the nuclei involved in stellar evolution are short-lived. Therefore, indirect methods became the focus of recent studies carried out in major nuclear physics facilities. Among such methods, heavy ion charge exchange is thought to be a useful tool to infer Gamow-Teller matrix elements needed to describe electron capture rates in stars and also double beta-decay experiments. In this short review, I provide a theoretical guidance based on a simple reaction model for charge exchange reactions.

Gadolinium neutron capture therapy

International Nuclear Information System (INIS)

Akine, Yasuyuki; Tokita, Nobuhiko; Tokuuye, Koichi; Satoh, Michinao; Churei, Hisahiko

1993-01-01

Gadolinium neutron capture therapy makes use of photons and electrons produced by nuclear reactions between gadolinium and lower-energy neutrons which occur within the tumor. The results of our studies have shown that its radiation effect is mostly of low LET and that the electrons are the significant component in the over-all dose. The dose from gadolinium neutron capture reactions does not seem to increase in proportion to the gadolinium concentration, and the Gd-157 concentration of about 100 μg/ml appears most optimal for therapy. Close contact between gadolinium and the cell is not necessarily required for cell inactivation, however, the effect of electrons released from intracellular gadolinium may be significant. Experimental studies on tumor-bearing mice and rabbits have shown that this is a very promising modality though further improvements in gadolinium delivery to tumors are needed. (author)

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

International Nuclear Information System (INIS)

Shaughnessy, Dawn A.

2000-01-01

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

Single-electron-capture processes in collisions of He2+, Liq+ (q=1,2,3), C6+, and O8+ ions with helium

International Nuclear Information System (INIS)

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

2011-01-01

Cross sections for single-electron capture in collisions of He 2+ , Li q+ (q = 1,2,3), C 6+ , and O 8+ ions with helium atoms at incident energy ranging from 50 to 5000 keV/amu have been calculated in the framework of four-body boundary-corrected continuum intermediate state (BCCIS-4B) approximation in both prior and post forms. In this formalism, distortion in the final channel related to the Coulomb continuum states of the projectile ion and the active electron in the field of residual target ion are included. In all cases, total single-electron-capture cross sections have been calculated by summing over all contributions up to n = 3 shells and subshells, respectively. It has been observed that the contribution of the capture cross section into the excited states is significant for asymmetric collision (Z P >Z T ) and is insignificant for symmetric collision. Numerical results for the total cross sections show good agreement with the available experimental findings, particularly in the post form. Post-prior discrepancy has been found to be within 30% except for Li + + He interactions below 150 keV/amu.

Calibration of radionuclides with decay trough beta emission or electron capture by liquid scintillation technique

International Nuclear Information System (INIS)

Loureiro, Jamir dos Santos

2000-02-01

In this work is reported a methodology a methodology for pure beta and electron capture radionuclides standardization, suing liquid scintillation technique. In this sense the CIEMAT/NIST method, recently utilized by international laboratories, was implemented and the lack in the Laboratorio Nacional das Radiacoes Ionizantes - LNMRI, of the Comissao Nacional de Energia Nuclear - CNEN, for adequate methodology to standardize this kind if radionuclides was filled, fact that was not present with alpha and gamma radionuclides. The implementation procedure evaluation was provided by concentration activity determination of the following radionuclides: 14 C and 90 Sr, pure beta emitters; 55 Fe, electron capture decay; 204 Tl, electron capture and beta decay and 60 Co, beta-gamma emitter. In this way, a careful analysis of the implementation procedure with these radionuclides types, ranging on a broad energy spectral, was possible. To check the calibration results, intercomparisons among our measurements of these radionuclides and the reference values of the CIEMAT/Spain laboratory were provided. To check the calibration results, intercomparisons among our measurements of these radionuclides and the reference values of the CIEMAT/Spain laboratory were provided. Besides this intercomparisons, one was provided with a 204 Tl solution, utilized in the international comparison recently promoted by BIPM, and another one with a 60 C solution calibrated in LNMRI/CNEN previously by a relative calibration system, with a well type pressurized ionization chamber, and an absolute beta-gamma coincidence system, with a pill-box type proportional counter 4 π geometry, coupled with a scintillator system with a sodium iodide cristal of 4x4 inches. The comparisons among LNMRI/CNEN results and the reference values, showed a small deviation of 1,32% for 14 C, 0,40% for 60 Co, 1,12% for 55 Fe, 0,10% for 90 Sr and 0,73% for 204 Tl. For the BIPM solution the deviation was 0,46% and for 60 Co

Intermolecular effects on the radiogenic formation of electron-capture phosphorus-centered radicals. A single-crystal ESR study of diastereoisomeric precursors

Energy Technology Data Exchange (ETDEWEB)

Aagaard, O.M.; Janssen, R.A.J.; de Waal, B.F.M.; Buck, H.M. (Eindhoven Univ. of Technology (Netherlands))

1990-01-31

ESR experiments on X-irradiated single crystals of the 2R,4S,5R and 2S,4S,5R diastereoisomers of 2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide reveal that the yield of radiogenic electron-capture reactions in the solid state strongly depends on intermolecular interactions in the crystal. In the present case a high yield of P-Cl three-electron-bond phosphoranyl radical anions is found in crystals of the 2R,4S,5R isomer, whereas no radical formation can be detected for the 2S,4S,5R isomer. An analysis of nonbonded interactions with neighboring molecules reveals that the geometry relaxation necessary for the radical stabilization is easily accommodated in crystals of the 2R,4S,SR isomer but not in the 2S,4S,5R isomer, explaining the observed difference in electron-capture efficiency. Experiments on radical formation in a MeTHF host matrix give further insight into the importance of the environment on radiogenic radical formation. The possible concurrent effect of the matrix on the electronic configuration and spin density distribution of the resulting phosphoranyl radical is discussed.

Intermolecular effects on the radiogenic formation of electron-capture phosphorus-centered radicals. A single-crystal ESR study of diastereoisomeric precursors

International Nuclear Information System (INIS)

Aagaard, O.M.; Janssen, R.A.J.; de Waal, B.F.M.; Buck, H.M.

1990-01-01

ESR experiments on X-irradiated single crystals of the 2R,4S,5R and 2S,4S,5R diastereoisomers of 2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide reveal that the yield of radiogenic electron-capture reactions in the solid state strongly depends on intermolecular interactions in the crystal. In the present case a high yield of P-Cl three-electron-bond phosphoranyl radical anions is found in crystals of the 2R,4S,5R isomer, whereas no radical formation can be detected for the 2S,4S,5R isomer. An analysis of nonbonded interactions with neighboring molecules reveals that the geometry relaxation necessary for the radical stabilization is easily accommodated in crystals of the 2R,4S,SR isomer but not in the 2S,4S,5R isomer, explaining the observed difference in electron-capture efficiency. Experiments on radical formation in a MeTHF host matrix give further insight into the importance of the environment on radiogenic radical formation. The possible concurrent effect of the matrix on the electronic configuration and spin density distribution of the resulting phosphoranyl radical is discussed

Atomic and nuclear parameters of single electron capture decaying nuclides; Constantes atomicas y nucleares de nucleidos que se desintegran por captura electronica pura

Energy Technology Data Exchange (ETDEWEB)

Grau, A

1981-07-01

Atomic and nuclear parameters of the following nuclides which decay by electron capture have been calculated: 37{sup A}r, 41{sup C}a, 49{sup V}, 53{sup M}n, 55{sup F}e,59{sup N}i, 68Ge,82{sup S}r, 97{sup T}c, 118{sup T}e, 131{sup C}s, 137{sup L}a, 140{sup N}d, 157{sup T}b, 165{sup E}r, 193{sup p}t, 194{sup H}g, and 205{sup P}h The evaluation rules are included in the first part of the paper. The values and the associated uncertainties of the following parameters have been tabulated: decay energy, electron capture probabilities, fluorescence yield, electron emission and X-ray emission. (Author) 27 refs.

Electron irradiation-induced destruction of carbon nanotubes in electron microscopes

International Nuclear Information System (INIS)

Molhave, Kristian; Gudnason, Sven Bjarke; Pedersen, Anders Tegtmeier; Clausen, Casper Hyttel; Horsewell, Andy; Boggild, Peter

2007-01-01

Observations of carbon nanotubes under exposure to electron beam irradiation in standard transmission electron microscope (TEM) and scanning electron microscope (SEM) systems show that such treatment in some cases can cause severe damage of the nanotube structure, even at electron energies far below the approximate 100 keV threshold for knock-on damage displacing carbon atoms in the graphene structure. We find that the damage we observe in one TEM can be avoided by use of a cold finger. This and the morphology of the damage imply that water vapour, which is present as a background gas in many vacuum chambers, can damage the nanotube structure through electron beam-induced chemical reactions. Though, the dependence on the background gas makes these observations specific for the presently used systems, the results demonstrate the importance of careful assessment of the level of subtle structural damage that the individual electron microscope system can do to nanostructures during standard use

Radiation-induced electron migration in nucleic acids

International Nuclear Information System (INIS)

Fuciarelli, A.F.; Sisk, E.C.; Miller, J.H.; Zimbrick, J.D.

1994-01-01

Radiation-induced electron migration along DNA is a mechanism by which randomly produced stochastic energy deposition events can lead to non-random types of damage along DNA manifested distal to the sites of the initial energy deposition. Radiation-induced electron migration in nucleic acids has been examined using oligonucleotides containing 5-bromouracil (5-BrU). Interaction of 5-BrU with solvated electrons results in release of bromide ions and formation of uracil-5-yl radicals. Monitoring either bromide ion release or uracil formation provides an opportunity to study electron migration processes in model nucleic acid systems. Using this approach we have discovered that electron migration along oligonucleotides is significantly influenced by the base sequence and strandedness. Migration along 7 base pairs in oligonucleotides containing guanine bases was observed for oligonucleotides irradiated in solution, which compares with mean migration distances of 6-10 bp for Escherichia coli DNA irradiated in solution and 5.5 bp for E. coli DNA irradiated in cells. Evidence also suggests that electron migration can occur preferentially in the 5' to 3' direction along a double-stranded oligonucleotide containing a region of purine bases adjacent to the 5-BrU moiety. Our continued efforts will provide information regarding the contribution of electron transfer along DNA to formation of locally multiply damaged sites created in DNA by exposure to ionizing radiation. (Author)

A critical literature review of focused electron beam induced deposition

International Nuclear Information System (INIS)

Dorp, W. F. van; Hagen, C. W.

2008-01-01

An extensive review is given of the results from literature on electron beam induced deposition. Electron beam induced deposition is a complex process, where many and often mutually dependent factors are involved. The process has been studied by many over many years in many different experimental setups, so it is not surprising that there is a great variety of experimental results. To come to a better understanding of the process, it is important to see to which extent the experimental results are consistent with each other and with the existing model. All results from literature were categorized by sorting the data according to the specific parameter that was varied (current density, acceleration voltage, scan patterns, etc.). Each of these parameters can have an effect on the final deposit properties, such as the physical dimensions, the composition, the morphology, or the conductivity. For each parameter-property combination, the available data are discussed and (as far as possible) interpreted. By combining models for electron scattering in a solid, two different growth regimes, and electron beam induced heating, the majority of the experimental results were explained qualitatively. This indicates that the physical processes are well understood, although quantitatively speaking the models can still be improved. The review makes clear that several major issues remain. One issue encountered when interpreting results from literature is the lack of data. Often, important parameters (such as the local precursor pressure) are not reported, which can complicate interpretation of the results. Another issue is the fact that the cross section for electron induced dissociation is unknown. In a number of cases, a correlation between the vertical growth rate and the secondary electron yield was found, which suggests that the secondary electrons dominate the dissociation rather than the primary electrons. Conclusive evidence for this hypothesis has not been found. Finally

Metadata capture in an electronic notebook: How to make it as simple as possible?

Directory of Open Access Journals (Sweden)

Menzel, Julia

2015-09-01

Full Text Available In the last few years electronic laboratory notebooks (ELNs have become popular. ELNs offer the great possibility to capture metadata automatically. Due to the high documentation effort metadata documentation is neglected in science. To close the gap between good data documentation and high documentation effort for the scientists a first user-friendly solution to capture metadata in an easy way was developed.At first, different protocols for the Western Blot were collected within the Collaborative Research Center 1002 and analyzed. Together with existing metadata standards identified in a literature search a first version of the metadata scheme was developed. Secondly, the metadata scheme was customized for future users including the implementation of default values for automated metadata documentation.Twelve protocols for the Western Blot were used to construct one standard protocol with ten different experimental steps. Three already existing metadata standards were used as models to construct the first version of the metadata scheme consisting of 133 data fields in ten experimental steps. Through a revision with future users the final metadata scheme was shortened to 90 items in three experimental steps. Using individualized default values 51.1% of the metadata can be captured with present values in the ELN.This lowers the data documentation effort. At the same time, researcher could benefit by providing standardized metadata for data sharing and re-use.

Electron-electron interaction and transfer ionization in fast ion-atom collisions

International Nuclear Information System (INIS)

Voitkiv, A B

2008-01-01

Recently it was pointed out that electron capture occurring in fast ion-atom collisions can proceed via a mechanism which earlier was not considered. In the present paper we study this mechanism in more detail. Similarly as in radiative capture, where the electron transfer occurs due to the interaction with the radiation field and proceeds via emission of a photon, within this mechanism the electron capture is caused by the interaction with another atomic electron leading mainly to the emission of the latter. In contrast to the electron-electron Thomas capture, this electron-electron (E-E) mechanism is basically a first-order one having similarities to the kinematic and radiative capture channels. It also possesses important differences with the latter two. Leading to transfer ionization, this first-order capture mechanism results in the electron emission mainly in the direction opposite to the motion of the projectile ion. The same, although less pronounced, feature is also characteristic for the momenta of the target recoil ions produced via this mechanism. It is also shown that the action of the E-E mechanism is clearly seen in recent experimental data on the transfer ionization in fast proton-helium collisions.

Analysis of neonicotinoids by gas chromatography coupled to nuclide {sup 63}Ni - Electron Capture Detector - GC/ECD

Energy Technology Data Exchange (ETDEWEB)

Amaral, Priscila O.; Leao, Claudio; Redigolo, Marcelo M.; Crepaldi, Caike; Bustillos, Oscar V., E-mail: priscilaoamaral@gmail.com, E-mail: claudio.leao@usp.br, E-mail: marceloredigolo@gmail.com, E-mail: caike1995@gmail.com, E-mail: ovega@ipen.bremails [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

Recently, several reports have been published discussing reduction in bee population which polymerizes cultures around the world this phenomenon is known as Colony Collapse Disorder (CCD). The phenomenon describes the lack of worker honeybees in the colony despite having pups and food. The causes of this problem are unknown but there are studies that claim that reduction of population of bees is linked to poisoning through insecticides specifically neonicotinoids. Among this type of pesticide are imidacloprid (C{sub 9}H{sub 10}ClN{sub 5}O{sub 2}), clothianidin (C{sub 6}H{sub 8}ClN{sub 5}O{sub 2}S) and thiamethoxam (C{sub 8}H{sub 10}ClN{sub 5}O{sub 3}S). This paper presents the analysis of neonicotinoids - clothianidin, imidacloprid and thiamethoxam - by the technique of gas chromatography coupled to nuclide {sup 63}Ni electron capture detector (GC/ECD). The electron capture detector (ECD) is a gas chromatography detector that has been used for the detection of organic halogens, nitriles, nitrates and organometallic compounds. The ECD detector ionizes the analytes by the beta particles from the nuclide sources {sup 63}Ni within carrier gas N{sub 2}. The electrons produced in this process are collected and create a current that are amplified and generates a chromatographic peak. Methodology and details of the analysis are present in this work. (author)

Low energy electron capture in collisions of C3+ with He

International Nuclear Information System (INIS)

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

2009-06-01

Charge transfer processes due to collisions of ground state C 3+ (1s 2 2s 2 S) ions with He atom are investigated using the quantum-mechanical molecular-orbital close-coupling (QMOCC) method for energies between 10 -4 eV/u and 10 3 eV/u. The ab initio adiabatic potential and radial coupling utilized in the QMOCC calculations are obtained from the multi-reference single- and double-excitation configuration interaction (MRD-CI) approach. Total and state-selective single electron capture (SEC) cross sections and rate coefficients are obtained and compared with the available experimental and theoretical data. Good agreement between the measured SEC cross sections and the present calculation is found, but the previous calculation of total rate coefficient using the Landau-Zener model is one or two orders of magnitude smaller than the present result. (author)

Capturing Chemistry in Action with Electrons: Realization of Atomically Resolved Reaction Dynamics.

Science.gov (United States)

Ischenko, Anatoly A; Weber, Peter M; Miller, R J Dwayne

2017-08-23

One of the grand challenges in chemistry has been to directly observe atomic motions during chemical processes. The depiction of the nuclear configurations in space-time to understand barrier crossing events has served as a unifying intellectual theme connecting the different disciplines of chemistry. This challenge has been cast as an imaging problem in which the technical issues reduce to achieving not only sufficient simultaneous space-time resolution but also brightness for sufficient image contrast to capture the atomic motions. This objective has been met with electrons as the imaging source. The review chronicles the first use of electron structural probes to study reactive intermediates, to the development of high bunch charge electron pulses with sufficient combined spatial-temporal resolution and intensity to literally light up atomic motions, as well as the means to characterize the electron pulses in terms of temporal brightness and image reconstruction. The use of femtosecond Rydberg spectroscopy as a novel means to use internal electron scattering within the molecular reference frame to obtain similar information on reaction dynamics is also discussed. The focus is on atomically resolved chemical reaction dynamics with pertinent references to work in other areas and forms of spectroscopy that provide additional information. Effectively, we can now directly observe the far-from-equilibrium atomic motions involved in barrier crossing and categorize chemistry in terms of a power spectrum of a few dominant reaction modes. It is this reduction in dimensionality that makes chemical reaction mechanisms transferrable to seemingly arbitrarily complex (large N) systems, up to molecules as large as biological macromolecules (N > 1000 atoms). We now have a new way to reformulate reaction mechanisms using an experimentally determined dynamic mode basis that in combination with recent theoretical advances has the potential to lead to a new conceptual basis for

Electronic capture of patient-reported and clinician-reported outcome measures in an elective orthopaedic setting: a retrospective cohort analysis.

Science.gov (United States)

Malhotra, Karan; Buraimoh, Olatunbosun; Thornton, James; Cullen, Nicholas; Singh, Dishan; Goldberg, Andrew J

2016-06-20

To determine whether an entirely electronic system can be used to capture both patient-reported outcomes (electronic Patient-Reported Outcome Measures, ePROMs) as well as clinician-validated diagnostic and complexity data in an elective surgical orthopaedic outpatient setting. To examine patients' experience of this system and factors impacting their experience. Retrospective analysis of prospectively collected data. Single centre series. Outpatient clinics at an elective foot and ankle unit in the UK. All new adult patients attending elective orthopaedic outpatient clinics over a 32-month period. All patients were invited to complete ePROMs prior to attending their outpatient appointment. At their appointment, those patients who had not completed ePROMs were offered the opportunity to complete it on a tablet device with technical support. Matched diagnostic and complexity data were captured by the treating consultant during the appointment. Capture rates of patient-reported and clinician-reported data. All information and technology (IT) failures, language and disability barriers were captured. Patients were asked to rate their experience of using ePROMs. The scoring systems used included EQ-5D-5L, the Manchester-Oxford Foot Questionnaire (MOxFQ) and the Visual Analogue Scale (VAS) pain score. Out of 2534 new patients, 2176 (85.9%) completed ePROMs, of whom 1090 (50.09%) completed ePROMs at home/work prior to their appointment. 31.5% used a mobile (smartphone/tablet) device. Clinician-reported data were captured on 2491 patients (98.3%). The mean patient experience score of using Patient-Reported Outcome Measures (PROMs) was 8.55±1.85 out of 10 and 666 patients (30.61%) left comments. Of patients leaving comments, 214 (32.13%) felt ePROMs did not adequately capture their symptoms and these patients had significantly lower patient experience scores (ptechnology into a service improvement programme. Excellent capture rates of ePROMs and clinician

The coulometric electron capture detector and its application to the selected freons in water and air. Part of a coordinated programme on the analysis of organic compounds by electron capture gas chromatography

International Nuclear Information System (INIS)

Lasa, J.

1981-01-01

In developing the use of Freon-11 and Freon-12 as environmental tracers in aeronomy, oceanography and hydrology electron capture gas chromatography was used to measure the concentration changes. A detector in the coulometric mode was designed and operated as a solute switch. The detection limit was in the order of 0.2x10 -12 g for a modified head space method in handling aqueous samples. Theoretical analysis of the detector design and the effects of factors including pulsing period, flowrates of carrier gas and the radioactivity of the detector source were discussed and confirmed experimentally

Northwestcape-induced Electron Precipitation and Theoretica Simulation

Science.gov (United States)

Zhang, Z.; Li, X.; Wang, C.; Chen, L.

2017-12-01

Enhancement of the electron fluxes in the inner radiation belt, which is induced by the powerful North West Cape (NWC) very-low-frequency (VLF) transmitter, have been observed and analyzed by several research groups. However, all of the previous publications have focused on NWC-induced > 100-keV electrons only, based on observations from the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and the Geostationary Operational Environmental Satellite (GOES) satellites. Here, we present flux enhancements with 30-100-keV electrons related to NWC transmitter for the first time, which were observed by the GOES satellite at night. Similar to the 100- 300-keV precipitated-electron behavior, the low energy 30-100-keV electron precipitation is primarily located east of the transmitter. However, the latter does not drift eastward to the same extent as the former, possibly because of the lower electron velocity. The 30-100-keV electrons are distributed in the L = 1.8-2.1 L-shell range, in contrast to the 100-300-keVelectronswhichareatL=1.67-1.9. ThisisconsistentwiththeperspectivethattheenergyoftheVLF-waveinducedelectronfluxenhancementdecreaseswithhigherL-shellvalues. Weexpandupontherationalityofthesimultaneous enhancementofthe30-100-and100-300-keVelectronfluxesthroughcomparisonwiththecyclotronresonancetheoryfor the quasi-linear wave-particle interaction. In addition, we interpret the asymmetry characteristics of NWC electric power distribution in northand south hemisphere by ray tracing model. Finally, we present considerable discussionand showthat good agreement exists between the observation of satellites and theory.

Double capture in the O8+ + He collision investigated by electron spectroscopy (80 keV, 10 deg)

International Nuclear Information System (INIS)

Moretto-Capelle, P.; Benoit-Cattin, P.; Bordenave-Montesquieu, A.; Boudjema, M.; Gleizes, A.; Dousson, S.; Hitz, D.

1989-01-01

Double capture into (3,n) autoionising states of O 6+ is observed in the O 8+ + He collision system by electron spectroscopy at 80 keV, 10 0 . A comparison of the experimental results with theoretical positions and lifetimes allows the (3,3) states as well as three groups of (3,4) states to be identified. The present experimental findings are compared with earlier data for the N 7+ + He and Ne 8+ (1s 2 ) + He systems. The influence of the core of the multicharged ion is studied by examining the O 8+ and Ne 8+ (1s 2 ) results. The total double capture cross section is found to be large and it is compared with available experimental and theoretical data. (author)

Elemental process of amorphization induced by electron irradiation in Si

International Nuclear Information System (INIS)

Yamasaki, Jun; Takeda, Seiji; Tsuda, Kenji

2002-01-01

We recently found that amorphization is induced in Si by electron irradiation. Examining the amorphization systematically, we have established the diagram of steady states under electron irradiation, either amorphous Si (a-Si) or crystalline Si (c-Si) as a function of incident electron energy, electron dose, and irradiation temperature. Utilizing transmission electron microscopy, electron energy filtered diffraction and electron energy-loss spectroscopy, we have characterized the atomic structure, the electronic structure, and the thermal stability of a-Si induced by electron irradiation. Based on the experimental data, we have also concluded that the amorphization is caused by the accumulation of not point defects but small cascade damages. Analyzing the change in the intensity of halo diffraction rings during amorphization, we have clarified that the smallest cascade damage that contributes to amorphization includes only about four Si atoms. This presumably supports the amorphization mechanism that four self-interstitial atoms form the quasistable structure I4 in c-Si and it becomes an amorphous embryo

Proposed ripplon induced weak localization of electrons over liquid helium

International Nuclear Information System (INIS)

Dahm, A.J.

1997-01-01

Ripplon induced weak localization is proposed for electrons on a liquid helium surface. Ripplon scattering is quasi-elastic, the ripplon are quasi-static relative to the electron velocity, and the relative change in occupation number of the ripplon state in a scattering event is small. Conditions for the observation of ripplon induced weak localization are calculated

Alignment in double capture processes

International Nuclear Information System (INIS)

Moretto-Capelle, P.; Benhenni, M.; Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.

1993-01-01

The electron spectra emitted when a double capture occurs in N 7+ +He and Ne 8+ +He systems at 10 qkeV collisional energy, allow us to determine the angular distributions of the 3 ell 3 ell ' lines through a special spectra fitting procedure which includes interferences between neighbouring states. It is found that the doubly excited states populated in double capture processes are generally aligned

Double electron capture in collisions of the helium-like ions N5+, O6+ and Ne8+ with helium atoms

International Nuclear Information System (INIS)

Boudjema, M.; Moretto-Capelle, P.; Bordenave-Montesquieu, A.

1989-01-01

A fitting procedure of 1s 2 3l3l' lines observed in A (z-2)+ (1s 2 )+He collisions (Z = 7, 8 and 10), at 10 q keV collision energy (q = Z -2) and 10 0 observation angle, allows us to compare new theoretical positions and lifetimes, and experimental electron spectra. It is found that the spin conservation rule holds and that only singlet states are populated in these capture processes. As in N 7+ and O 8+ + He systems, capture into the highest angular momentum 1 G state is favoured in O 6+ and Ne 8+ + He systems and accounts for 26% of the double capture at 10 0 . In N 5+ + He, the L distribution is broader and no L value is clearly predominant. (author)

Calculation on spectrum of direct DNA damage induced by low-energy electrons including dissociative electron attachment.

Science.gov (United States)

Liu, Wei; Tan, Zhenyu; Zhang, Liming; Champion, Christophe

2017-03-01

In this work, direct DNA damage induced by low-energy electrons (sub-keV) is simulated using a Monte Carlo method. The characteristics of the present simulation are to consider the new mechanism of DNA damage due to dissociative electron attachment (DEA) and to allow determining damage to specific bases (i.e., adenine, thymine, guanine, or cytosine). The electron track structure in liquid water is generated, based on the dielectric response model for describing electron inelastic scattering and on a free-parameter theoretical model and the NIST database for calculating electron elastic scattering. Ionization cross sections of DNA bases are used to generate base radicals, and available DEA cross sections of DNA components are applied for determining DNA-strand breaks and base damage induced by sub-ionization electrons. The electron elastic scattering from DNA components is simulated using cross sections from different theoretical calculations. The resulting yields of various strand breaks and base damage in cellular environment are given. Especially, the contributions of sub-ionization electrons to various strand breaks and base damage are quantitatively presented, and the correlation between complex clustered DNA damage and the corresponding damaged bases is explored. This work shows that the contribution of sub-ionization electrons to strand breaks is substantial, up to about 40-70%, and this contribution is mainly focused on single-strand break. In addition, the base damage induced by sub-ionization electrons contributes to about 20-40% of the total base damage, and there is an evident correlation between single-strand break and damaged base pair A-T.

Enhancing Protein Disulfide Bond Cleavage by UV Excitation and Electron Capture Dissociation for Top-Down Mass Spectrometry

OpenAIRE

Wongkongkathep, Piriya; Li, Huilin; Zhang, Xing; Loo, Rachel R. Ogorzalek; Julian, Ryan R.; Loo, Joseph A.

2015-01-01

The application of ion pre-activation with 266 nm ultraviolet (UV) laser irradiation combined with electron capture dissociation (ECD) is demonstrated to enhance top-down mass spectrometry sequence coverage of disulfide bond containing proteins. UV-based activation can homolytically cleave a disulfide bond to yield two separated thiol radicals. Activated ECD experiments of insulin and ribonuclease A containing three and four disulfide bonds, respectively, were performed. UV-activation in comb...

CAMAC - supported electronic set-up for the determination of the capture cross section of the reaction 1H(n,d)γ

International Nuclear Information System (INIS)

Hutsch, J.; Moeller, K.; Moesner, J.; Neubert, W.; Pilz, W.; Schmidt, G.; Stiehler, T.; Kudin, L.G.; Spiridenkov, E.M.; Volkov, S.S.

1984-08-01

After a brief description of the physical problem the experimental apparatus and the electronic set-up for the investigation of the capture reaction 1 H(n,d)γ at E/sub n/ = 25 MeV are described. (author)

Formation of negative hydrogen ion: polarization electron capture and nonthermal shielding.

Science.gov (United States)

Ki, Dae-Han; Jung, Young-Dae

2012-09-07

The influence of the nonthermal shielding on the formation of the negative hydrogen ion (H(-)) by the polarization electron capture are investigated in partially ionized generalized Lorentzian plasmas. The Bohr-Lindhard method has been applied to obtain the negative hydrogen formation radius and cross section as functions of the collision energy, de Broglie wave length, Debye length, impact parameter, and spectral index of the plasma. The result shows that the nonthermal character of the plasma enhances the formation radius of the negative hydrogen, especially, for small Debye radii. It is found that the nonthermal effect increases the formation cross section of the negative hydrogen. It is also found that the maximum position of the formation cross section approaches to the collision center with an increase of the spectral index. In addition, it is found that the formation cross section significantly decreases with an increase of the Debye length, especially, for small spectral indices.

Formation of negative hydrogen ion: Polarization electron capture and nonthermal shielding

International Nuclear Information System (INIS)

Ki, Dae-Han; Jung, Young-Dae

2012-01-01

The influence of the nonthermal shielding on the formation of the negative hydrogen ion (H − ) by the polarization electron capture are investigated in partially ionized generalized Lorentzian plasmas. The Bohr-Lindhard method has been applied to obtain the negative hydrogen formation radius and cross section as functions of the collision energy, de Broglie wave length, Debye length, impact parameter, and spectral index of the plasma. The result shows that the nonthermal character of the plasma enhances the formation radius of the negative hydrogen, especially, for small Debye radii. It is found that the nonthermal effect increases the formation cross section of the negative hydrogen. It is also found that the maximum position of the formation cross section approaches to the collision center with an increase of the spectral index. In addition, it is found that the formation cross section significantly decreases with an increase of the Debye length, especially, for small spectral indices.

Ion induced high energy electron emission from copper

International Nuclear Information System (INIS)

Ruano, G.; Ferron, J.

2008-01-01

We present measurements of secondary electron emission from Cu induced by low energy bombardment (1-5 keV) of noble gas (He + , Ne + and Ar + ) and Li + ions. We identify different potential and kinetic mechanisms and find the presence of high energetic secondary electrons for a couple of ion-target combinations. In order to understand the presence of these fast electrons we need to consider the Fermi shuttle mechanism and the different ion neutralization efficiencies.

Electron beam induced conductivity in 'PET' and 'FEP'

International Nuclear Information System (INIS)

Walzade, S.J.; Jog, J.P.; Dake, S.B.; Bhoraskar, S.V.

1983-01-01

Electron Beam Induced Conductivity (EBIC), classified into EBIC (bulk) and EBIC (surface) have been measured in PET and FEP respectively. The peculiar oscillatory nature of the induced gain versus beam energy variations is explained in terms of the spatial distributions of the trapping centres near the surface of the polymers. (author)

The role of electron-stimulated desorption in focused electron beam induced deposition

DEFF Research Database (Denmark)

van Dorp, Willem F.; Hansen, Thomas Willum; Wagner, Jakob Birkedal

2013-01-01

We present the results of our study about the deposition rate of focused electron beam induced processing (FEBIP) as a function of the substrate temperature with the substrate being an electron-transparent amorphous carbon membrane. When W(CO)6 is used as a precursor it is observed that the growt......, the majority desorbs from the surface rather than dissociates to contribute to the deposit. It is important to take this into account during FEBIP experiments, for instance when determining fundamental process parameters such as the activation energy for desorption....... experiments compared to literature values is consistent with earlier findings by other authors. The discrepancy is attributed to electron-stimulated desorption, which is known to occur during electron irradiation. The data suggest that, of the W(CO)6 molecules that are affected by the electron irradiation...

Design of electron detection system for pulse electron irradiator

International Nuclear Information System (INIS)

Anjar Anggraini H; Agus Purwadi; Lely Susita RM; Bambang Siswanto; Agus Wijayanto

2016-01-01

Design of electron detection system for pulse electron irradiator has been conducted on the Plasma Cathode Electron Source by Rogowski coil technique. Rogowski coil has ability to capture the induced magnetic field of the electric current, subsequent induced magnetic field will provide voltage after passing integrator. This diagnostic used combination of copper wire, ferrite and RC integrator. The design depends on the pulse width and the value of plasma current that passes through the coil, thus the number of windings, coil area and integrator can be designed. For plasma spots current of IDPS expected to be 10 A and pulse width 10 μs the Rogowski coil using MnZn ferrite with inductance L = 0.275 mH and permeability μr = 200 H/m. For the current of plasma arc ADPS expected to be 100 A and pulse width 100 μs by using inductance L=1.9634 mH and permeability μr = 6256 H/m. Electron current in extraction system expected to be 30 A and pulse width 100 μs the Rogowski coil using inductance L=51.749 mH and permeability μr= 4987 H/m. Design integrator used is the type of RC integrator. (author)

Alignment in double capture processes

Energy Technology Data Exchange (ETDEWEB)

Moretto-Capelle, P.; Benhenni, M.; Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A. (IRSAMC, URA CNRS 770, Univ. Paul Sabatier, 118 rte de Narbonne, 31062 Toulouse Cedex (France))

1993-06-05

The electron spectra emitted when a double capture occurs in N[sup 7+]+He and Ne[sup 8+]+He systems at 10 qkeV collisional energy, allow us to determine the angular distributions of the 3[ell]3[ell] [prime] lines through a special spectra fitting procedure which includes interferences between neighbouring states. It is found that the doubly excited states populated in double capture processes are generally aligned.

Radiation-induced electron migration along DNA

International Nuclear Information System (INIS)

Fuciarelli, A.F.; Sisk, E.C.; Miller, J.H.; Zimbrick, J.D.

1994-04-01

Radiation-induced electron migration along DNA is a mechanism by which randomly produced stochastic energy deposition events can lead to nonrandom types of damage along DNA manifested distal to the sites of the initial energy deposition. Electron migration along DNA is significantly influenced by the DNA base sequence and DNA conformation. Migration along 7 base pairs in oligonucleotides containing guanine bases was observed for oligonucleotides irradiated in solution which compares to average migration distances of 6 to 10 bases for Escherichia coli DNA irradiated in solution and 5.5 base pairs for Escherichia coli DNA irradiated in cells. Evidence also suggests that electron migration can occur preferentially in the 5' to 3' direction along DNA. Our continued efforts will provide information regarding the contribution of electron transfer along DNA to formation of locally multiply damaged sites created in DNA by exposure to ionizing radiation

Lifetime of the long-lived isomer of /sup 236/Np from. cap alpha. -,. beta. - and electron-capture decay measurements

Energy Technology Data Exchange (ETDEWEB)

Lindner, M.; Dupzyk, R.J.; Hoff, R.W.; Nagle, R.J. (California Univ., Livermore (USA). Lawrence Livermore National Lab.)

1981-01-01

The half-life of long-lived /sup 236/Np, due to ..cap alpha.., ..beta.. and electron-capture decay, was found to be 1.55 x 10/sup 5/ yr. Of all decays, 88% populate excited states in /sup 236/U and 12% populate levels in /sup 236/Pu. Lifetimes measured by growth of the ground states of /sup 236/U and /sup 236/Pu agree with values from corresponding ..gamma.. de-excitations in these daughter nuclei. Therefore, nearly all the electron-capture decays populate the 6/sup +/ level of the ground-state band in /sup 236/U. Similarly, essentially all the ..beta../sup -/ decay populates an analogous 6/sup +/ level in /sup 236/Pu, which de-excites through a previously unreported transition of 158.3 keV. If a very week ..gamma..-ray at 894 keV can be ascribed to a level in /sup 232/U populated by ..beta.. decay of /sup 232/Pa, its existence establishes a 0.2% ..cap alpha..-branching decay in /sup 236/Np.

Seeing in 4D with electrons: development of ultrafast electron microscopy at Caltech

International Nuclear Information System (INIS)

Baskin, J.S.; Zewail, A.H.

2014-01-01

The vision to develop 4D electron microscopy, a union of the capabilities of electron microscopy with ultrafast techniques to capture clearly defined images of the nano-scale structure of a material at each step in the course of its chemical or physical transformations, has been pursued at Caltech for the last decade. In this contribution, we will give a brief overview of the capabilities of three currently active Caltech 4D microscopy laboratories. Ongoing work is illustrated by a description of the most recent application of photon-induced near-field electron microscopy (PINEM), a field made possible only by the development of the 4D ultrafast electron microscopy (UEM). An appendix gives the various applications made so far and the historic roots of the development at Caltech. (authors)

Tunneling induced electron transfer between separated protons

Science.gov (United States)

Vindel-Zandbergen, Patricia; Meier, Christoph; Sola, Ignacio R.

2018-04-01

We study electron transfer between two separated protons using local control theory. In this symmetric system one can favour a slow transfer by biasing the algorithm, achieving high efficiencies for fixed nuclei. The solution can be parametrized using a sequence of a pump followed by a dump pulse that lead to tunneling-induced electron transfer. Finally, we study the effect of the nuclear kinetic energy on the efficiency. Even in the absence of relative motion between the protons, the spreading of the nuclear wave function is enough to reduce the yield of electronic transfer to less than one half.

Iodide- and bromide-specific electron-capture/photodetachment-modulated detector for the trace analysis of halocarbon mixtures

International Nuclear Information System (INIS)

Mock, R.S.; Grimsrud, E.P.

1988-01-01

The use of photodetachment (PD) of electrons from negative ions in a pulsed electron capture detector (ECD) is described. By passing a chopped light beam through the ECD and amplification of the modulated component of the ECD signal, the photodetachment-modulated (PDM) pulsed ECD can be made to respond selectively and sensitively to iodine- containing hydrocarbons alone, or to iodine- and bromine-containing hydrocarbons in the presence of chlorinated hydrocarbons. The detection limit of the iodide/bromide-specific mode of the PDM-ECD to CH 3 I is shown to be competitive with that of the normal mode of the pulsed ECD. This detection mode of the ECD is shown to be of great assistance in the gas chromatographic analysis of organobromides and organoiodides in complex mixtures which contain a large number of organochlorides

Preclinical studies on gadolinium neutron capture therapy

International Nuclear Information System (INIS)

Akine, Yasuyuki

1994-01-01

Gadolinium neutron capture therapy is based on radiations (photons and electrons) produced in the tumor by a nuclear reaction between gadolinium and lower-energy neutrons. Studies with Chinese hamster cells have shown that the radiation effect resulting from gadolinium neutron capture reactions is mostly of low LET and that released electrons are the significant component in the over-all dose. Biological dosimetry revealed that the dose does not seem to increase in proportion to the gadolinium concentration, leading to a conclusion that there is a range of gadolinium concentrations most efficient for gadolinium neutron capture therapy. The in vivo studies with transplantable tumors in mice and rabbits have revealed that close contact between gadolinium and the cell is not necessarily required for cell inactivation and that gadolinium delivery selective to tumors is crucial. The results show that the potential of gadolinium neutron capture therapy as a therapeutic modality appears very promising. (author)

Ion induced high energy electron emission from copper

Energy Technology Data Exchange (ETDEWEB)

Ruano, G. [Instituto de Desarrollo Tecnologico para la Industria Quimica, Consejo Nacional de Investigaciones Cientificas y Tecnicas and Universidad Nacional del Litoral Gueemes 3450 CC 91, 3000 Santa Fe (Argentina)], E-mail: gdruano@ceride.gov.ar; Ferron, J. [Instituto de Desarrollo Tecnologico para la Industria Quimica, Consejo Nacional de Investigaciones Cientificas y Tecnicas and Universidad Nacional del Litoral Gueemes 3450 CC 91, 3000 Santa Fe (Argentina); Departamento de Ingenieria de Materiales, Facultad de Ingenieria Quimica, Consejo Nacional de Investigaciones Cientificas y Tecnicas and Universidad Nacional del Litoral Gueemes 3450 CC 91, 3000 Santa Fe (Argentina)

2008-11-15

We present measurements of secondary electron emission from Cu induced by low energy bombardment (1-5 keV) of noble gas (He{sup +}, Ne{sup +} and Ar{sup +}) and Li{sup +} ions. We identify different potential and kinetic mechanisms and find the presence of high energetic secondary electrons for a couple of ion-target combinations. In order to understand the presence of these fast electrons we need to consider the Fermi shuttle mechanism and the different ion neutralization efficiencies.

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

Energy Technology Data Exchange (ETDEWEB)

Shaughnessy, Dawn A. [Univ. of California, Berkeley, CA (United States)

2000-01-01

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

Single electron capture differential cross section in H+ + He collisions at intermediate and high collision energies

International Nuclear Information System (INIS)

Abufager, P N; Fainstein, P D; MartInez, A E; Rivarola, R D

2005-01-01

The generalized continuum distorted wave-eikonal initial state (CDW-EIS II) approximation is employed to study differential cross sections (DCS) for single electron capture in H + + He collisions at intermediate and high energies. Present results are compared with theoretical calculations obtained using the previous CDW-EIS formulation in order to show the importance of the description of the bound and continuum target states in the entrance and exit channels, respectively. Both DCS are also shown together with other theoretical results and with experimental data

Isotope separation by photoselective dissociative electron

International Nuclear Information System (INIS)

Stevens, C.G.

1978-01-01

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 is described. 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, 235 UF 6 is separated from a UF 6 mixture by selective excitation followed by dissociative electron capture into 235 UF 5 - and F

North west cape-induced electron precipitation and theoretical simulation

Science.gov (United States)

Zhang, Zhen-xia; Li, Xin-qiao; Wang, Chen-Yu; Chen, Lun-Jin

2016-11-01

Enhancement of the electron fluxes in the inner radiation belt, which is induced by the powerful North West Cape (NWC) very-low-frequency (VLF) transmitter, have been observed and analyzed by several research groups. However, all of the previous publications have focused on NWC-induced > 100-keV electrons only, based on observations from the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and the Geostationary Operational Environmental Satellite (GOES) satellites. Here, we present flux enhancements with 30-100-keV electrons related to NWC transmitter for the first time, which were observed by the GOES satellite at night. Similar to the 100-300-keV precipitated-electron behavior, the low energy 30-100-keV electron precipitation is primarily located east of the transmitter. However, the latter does not drift eastward to the same extent as the former, possibly because of the lower electron velocity. The 30-100-keV electrons are distributed in the L = 1.8-2.1 L-shell range, in contrast to the 100-300-keV electrons which are at L = 1.67-1.9. This is consistent with the perspective that the energy of the VLF-wave-induced electron flux enhancement decreases with higher L-shell values. We expand upon the rationality of the simultaneous enhancement of the 30-100- and 100-300-keV electron fluxes through comparison with the cyclotron resonance theory for the quasi-linear wave-particle interaction. In addition, we interpret the asymmetry characteristics of NWC electric power distribution in north and south hemisphere by ray tracing model. Finally, we present considerable discussion and show that good agreement exists between the observation of satellites and theory. Supported by the China Seismo-Electromagnetic Satellite Mission Ground-Based Verification Project of the Administration of Science, Technology, and Industry for National Defense and Asia-Pacific Space Cooperation Organization Project (APSCO-SP/PM-EARTHQUAKE).

Electron-stimulated purification of platinum nanostructures grown via focused electron beam induced deposition

Directory of Open Access Journals (Sweden)

Brett B. Lewis

2015-04-01

Full Text Available Platinum–carbon nanostructures deposited via electron beam induced deposition from MeCpPt(IVMe3 are purified during a post-deposition electron exposure treatment in a localized oxygen ambient at room temperature. Time-dependent studies demonstrate that the process occurs from the top–down. Electron beam energy and current studies demonstrate that the process is controlled by a confluence of the electron energy loss and oxygen concentration. Furthermore, the experimental results are modeled as a 2nd order reaction which is dependent on both the electron energy loss density and the oxygen concentration. In addition to purification, the post-deposition electron stimulated oxygen purification process enhances the resolution of the EBID process due to the isotropic carbon removal from the as-deposited materials which produces high-fidelity shape retention.

Neutron induced electron radiography

International Nuclear Information System (INIS)

Andrade, Marcos Leandro Garcia

2008-01-01

In the present paper a new radiography technique, the 'Neutron Induced Electron Radiography' - NIER, to inspect low thickness samples on the order of micra, has been developed. This technique makes use of low energy electrons as penetrating radiation generated from metallic gadolinium screens when irradiated by thermal neutrons. The conditions to obtain the best image for the conventional X-ray film Kodak-AA were determined by using a digital system to quantify the darkening level of the film. The irradiations have been performed at a radiography equipment installed at the beam-hole no. 8 of the 5 MW IEA-R1 nuclear research reactor of IPEN-CNEN/SP. The irradiation time to obtain the best radiography was 100 seconds and for such condition the technique was able to discern 1 μm in 24 μm of aluminum at a resolution of 32 μm. By visual comparison the images obtained by the NIER shown a higher quality when compared with the ones from other usual techniques the make use of electrons a penetrating radiation and films for image registration. Furthermore the use of the digital system has provided a smaller time for data acquisition and data analysis as well as an improvement in the image visualization. (author)

Secondary electron emission from textured surfaces

Science.gov (United States)

Huerta, C. E.; Patino, M. I.; Wirz, R. E.

2018-04-01

In this work, a Monte Carlo model is used to investigate electron induced secondary electron emission for varying effects of complex surfaces by using simple geometric constructs. Geometries used in the model include: vertical fibers for velvet-like surfaces, tapered pillars for carpet-like surfaces, and a cage-like configuration of interlaced horizontal and vertical fibers for nano-structured fuzz. The model accurately captures the secondary electron emission yield dependence on incidence angle. The model shows that unlike other structured surfaces previously studied, tungsten fuzz exhibits secondary electron emission yield that is independent of primary electron incidence angle, due to the prevalence of horizontally-oriented fibers in the fuzz geometry. This is confirmed with new data presented herein of the secondary electron emission yield of tungsten fuzz at incidence angles from 0-60°.

Electrically induced spontaneous emission in open electronic system

Science.gov (United States)

Wang, Rulin; Zhang, Yu; Yam, Chiyung; Computation Algorithms Division (CSRC) Team; Theoretical; Computational Chemistry (HKU) Collaboration

A quantum mechanical approach is formulated for simulation of electroluminescence process in open electronic system. Based on nonequilibrium Green's function quantum transport equations and combining with photon-electron interaction, this method is used to describe electrically induced spontaneous emission caused by electron-hole recombination. The accuracy and reliability of simulation depends critically on correct description of the electronic band structure and the electron occupancy in the system. In this work, instead of considering electron-hole recombination in discrete states in the previous work, we take continuous states into account to simulate the spontaneous emission in open electronic system, and discover that the polarization of emitted photon is closely related to its propagation direction. Numerical studies have been performed to silicon nanowire-based P-N junction with different bias voltage.

The Bells' Capture note TH-3054-CERN

Energy Technology Data Exchange (ETDEWEB)

Hartouni, Ed P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2014-01-29

This document revisits the paper by M. Bell and J. S. Bell “Capture of Cooling Electrons by Cool Protons” TH-3054-CERN (March 30, 1981). I expand the treatment to include e⁺e^- capture.

Test particle modeling of wave-induced energetic electron precipitation

International Nuclear Information System (INIS)

Chang, H.C.; Inan, U.S.

1985-01-01

A test particle computer model of the precipitation of radiation belt electrons is extended to compute the dynamic energy spectrum of transient electron fluxes induced by short-duration VLF wave packets traveling along the geomagnetic field lines. The model is adapted to estimate the count rate and associated spectrum of precipitated electrons that would be observed by satellite-based particle detectors with given geometric factor and orientation with respect to the magnetic field. A constant-frequency wave pulse and a lightning-induced whistler wave packet are used as examples of the stimulating wave signals. The effects of asymmetry of particle mirror heights in the two hemispheres and the atmospheric backscatter of loss cone particles on the computed precipitated fluxes are discussed

Heavy-Ion-Induced Electronic Desorption of Gas from Metals

CERN Document Server

Molvik, A W; Mahner, E; Kireeff Covo, M; Bellachioma, M C; Bender, M; Bieniosek, F M; Hedlund, E; Krämer, A; Kwan, J; Malyshev, O B; Prost, L; Seidl, P A; Westenskow, G; Westerberg, L

2007-01-01

During heavy-ion operation in several particle accelerators worldwide, dynamic pressure rises of orders of magnitude were triggered by lost beam ions that bombarded the vacuum chamber walls. This ion-induced molecular desorption, observed at CERN, GSI, and BNL, can seriously limit the ion beam lifetime and intensity of the accelerator. From dedicated test stand experiments we have discovered that heavy-ion-induced gas desorption scales with the electronic energy loss (dEe/dx) of the ions slowing down in matter; but it varies only little with the ion impact angle, unlike electronic sputtering.

Differential charge transfer and continuum electron capture studies for ions in atomic hydrogen. Final report, August 1, 1979-September 31, 1983

International Nuclear Information System (INIS)

Sellin, I.A.; Elston, S.B.

1983-01-01

A final technical narrative is given of progress and results obtained during the period August 1, 1979 through September 30, 1983 in a project designed to test existing theories of electron capture to continuum states of fully stripped nuclei traversing atomic hydrogen targets. 5 references

State-selective electron capture in collisions of ground and metastable O2+ ions with H(1s)

International Nuclear Information System (INIS)

Cabello, C N; Errea, L F; Fernandez, L; Mendez, L; Macias, A; Rabadan, I; Riera, A

2003-01-01

An ab initio calculation of the electron capture cross sections for collisions of ground and metastable states of O 2+ with H(1s) is presented. For impact energies between 0.125 and 3.4 keV amu -1 , we find good agreement between the cross sections from the ground state ion with the mixed beam experimental data of Phaneuf et al (Phaneuf A, Alvarez I, Meyer F W and Crandall D H 1982 Phys. Rev. A 26 1892)

Double capture in the O/sup 8+/ + He collision investigated by electron spectroscopy (80 keV, 10 deg)

Energy Technology Data Exchange (ETDEWEB)

Moretto-Capelle, P.; Benoit-Cattin, P.; Bordenave-Montesquieu, A.; Boudjema, M.; Gleizes, A.; Oza, D.H.; Dousson, S.; Hitz, D.

1989-01-28

Double capture into (3,n) autoionising states of O/sup 6+/ is observed in the O/sup 8+/ + He collision system by electron spectroscopy at 80 keV, 10/sup 0/. A comparison of the experimental results with theoretical positions and lifetimes allows the (3,3) states as well as three groups of (3,4) states to be identified. The present experimental findings are compared with earlier data for the N/sup 7+/ + He and Ne/sup 8+/(1s/sup 2/) + He systems. The influence of the core of the multicharged ion is studied by examining the O/sup 8+/ and Ne/sup 8+/(1s/sup 2/) results. The total double capture cross section is found to be large and it is compared with available experimental and theoretical data.

Ion induced electron emission statistics under Agm- cluster bombardment of Ag

Science.gov (United States)

Breuers, A.; Penning, R.; Wucher, A.

2018-05-01

The electron emission from a polycrystalline silver surface under bombardment with Agm- cluster ions (m = 1, 2, 3) is investigated in terms of ion induced kinetic excitation. The electron yield γ is determined directly by a current measurement method on the one hand and implicitly by the analysis of the electron emission statistics on the other hand. Successful measurements of the electron emission spectra ensure a deeper understanding of the ion induced kinetic electron emission process, with particular emphasis on the effect of the projectile cluster size to the yield as well as to emission statistics. The results allow a quantitative comparison to computer simulations performed for silver atoms and clusters impinging onto a silver surface.

PbSnTe:In compound: Electron capture levels, galvanomagnetic properties, and THz sensitivity

Energy Technology Data Exchange (ETDEWEB)

Ishchenko, D. V., E-mail: miracle4348@gmail.com; Klimov, A. E.; Shumsky, V. N.; Epov, V. S. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2016-12-15

A model of the Pb{sub 1–x}Sn{sub x}Te:In compound, based on concepts of the theory of disordered systems is considered. The temperature dependences of the Fermi-level position and carrier concentration are calculated depending on the indium doping level and are compared with experimental data. The transient current–voltage characteristics are calculated in the mode of injection from the contact and current limitation by space charge at various voltage-variation rates. The data obtained are compared with the experiments. It is demonstrated that the shape of the characteristics is controlled by the parameters of electron capture at localized states. Photocurrent relaxation in a magnetic field is studied, and the mechanism of such relaxation is discussed under the assumption of the magnetic freezing of carriers.

PAES: Positron annihilation induced Auger electron spectrometer

OpenAIRE

Hugenschmidt, Christoph

2015-01-01

Positron annihilation induced Auger electron spectroscopy (PAES) is a newly developed application for surface studies with high elemental selectivity and exceptional surface sensitivity. The instrument is operated by the Technische Universität München and is located at NEPOMUC.

Correlated electron capture in the impact parameter and final projectile charge-state dependence of ECC cusp production in 0.53 MeV u-1 F8+ + Ne

International Nuclear Information System (INIS)

Skutlartz, A.; Hagmann, S.; Schmidt-Boecking, H.

1988-01-01

The impact parameter dependence of ECC cusp electron production in collisions of fast, highly charged ions with atoms is investigated by measuring the scattered projectiles in coincidence with cusp electrons emitted at 0 0 with respect to the beam axis. The absolute probabilities for ECC cusp production show a maximum at b ≅ 0.10 au, decrease strongly for smaller impact parameters and more gently toward larger impact parameters. In addition the final charge state of the scattered projectile is also determined simultaneously for each collision event. The probabilities, as a function of the projectile final charge state, are large for the case where at least one or more electrons are simultaneously captured into bound states of the projectile, but are surprisingly small for collisions in which a projectile did not capture an electron into a bound state. (author)

Study of the surrogate-reaction method applied to neutron-induced capture cross sections

International Nuclear Information System (INIS)

Boutoux, G.; Jurado, B.; Méot, V.; Roig, O.; Mathieu, L.; Aïche, M.; Barreau, G.; Capellan, N.; Companis, I.; Czajkowski, S.; Schmidt, K.-H.; Burke, J.T.; Bail, A.; Daugas, J.M.; Faul, T.; Morel, P.; Pillet, N.; Théroine, C.; Derkx, X.; Sérot, O.

2012-01-01

Gamma-decay probabilities of 173 Yb and 176 Lu have been measured using the surrogate reactions 174 Yb( 3 He,αγ) 173 Yb* and 174 Yb( 3 He,pγ) 176 Lu*, respectively. For the first time, the gamma-decay probabilities have been obtained with two independent experimental methods based on the use of C 6 D 6 scintillators and Germanium detectors. Our results for the radiative-capture cross sections are several times higher than the corresponding neutron-induced data. To explain these differences, we have used our gamma-decay probabilities to extract rather direct information on the spin distributions populated in the transfer reactions used. They are about two times wider and the mean values are 3 to 4 ℏ higher than the ones populated in the neutron-induced reactions. As a consequence, in the transfer reactions neutron emission to the ground and first excited states of the residual nucleus is strongly suppressed and gamma-decay is considerably enhanced.

Mass measurements of neutron rich isotopes in the Fe region and electron capture processes in neutron star crusts

International Nuclear Information System (INIS)

Estrade, Alfredo; Matos, M.; Schatz, Hendrik; Amthor, A.M.; Beard, Mary; Brown, Edward; Bazin, D.; Becerril, A.; Elliot, T.; Gade, A.; Galaviz, D.; Gupta, Sanjib; Hix, William Raphael; Lau, Rita; Moeller, Peter; Pereira, J.; Portillo, M.; Rogers, A.M.; Shapira, Dan; Smith, E.; Stolz, A.; Wallace, M.; Wiescher, Michael

2011-01-01

Experimental knowledge of nuclear masses of exotic nuclei is important for understanding nuclear structure far from the valley of stability, and as a direct input into astrophysical models. Electron capture processes in the crust of accreting neutron stars have been proposed as a heat source that can affect the thermal structure of the star. Nuclear masses of very neutron-rich nuclides are necessary inputs to model the electron capture process. The time-of-flight (TOF) mass measurement technique allows measurements on very short-lived nuclei. It has been effectively applied using the fast fragment beams produced at the National Superconducting Cyclotron Lab (NSCL) to reach masses very far from stability. Measurements were performed for neutron-rich isotopes in the region of the N=32 and N=40 subshells, which coincides with the mass range of carbon superburst ashes. We discuss reaction network calculations performed to investigate the impact of our new measurements and to compare the effect of using different global mass models in the calculations. It is observed that the process is sensitive to the differences in the odd-even mass staggering predicted by the mass models, and our new result for 66Mn has a significant impact on the distribution of heat sources in the crust.

Electron capture on 20Ne and the ultimate fate of stars in the mass range 8-10 M⊙

International Nuclear Information System (INIS)

Kirsebom, Oliver S.; Cederkall, Joakim; Jenkins, David G.; Joshi, Pankaj; Julin, Rauno; Kankainen, Anu; Trzaska, Wladyslaw H.; Kibedi, Tibor; Tengblad, Olof

2016-01-01

Knowledge of the electron-capture rate on 20 Ne is of critical importance to understand the final evolution of stars in the mass range 8-10M⊙. A recent study has highlighted the importance of the second-forbidden transition between the ground states of 20 Ne and 20 F, which is believed to dominate the capture rate in an important temperature-density range. The strength of this transition is, however, not well constrained, neither experimentally nor theoretically, making an experimental determination highly desirable. The transition strength can be determined from the branching ratio of the inverse transition in the decay of 20 F, for which the experimental upper limit is 10 -5 , while the most recent theoretical prediction is 1.3 x 10 -6 . To facilitate an experimental determination of the branching ratio we are refurbishing an intermediate-image magnetic spectrometer capable of focusing 7 MeV electrons, and designing a scintillator detector surrounded by an active cosmic-ray veto shield, which will serve as an energy- dispersive device at the focal plane. In this contribution, GEANT4 simulations of the expected performance of the setup will be presented and the astrophysical motivation for the experiment will be discussed. (author)

PAES: Positron annihilation induced Auger electron spectrometer

Directory of Open Access Journals (Sweden)

Christoph Hugenschmidt

2015-08-01

Full Text Available Positron annihilation induced Auger electron spectroscopy (PAES is a newly developed application for surface studies with high elemental selectivity and exceptional surface sensitivity. The instrument is operated by the Technische Universität München and is located at NEPOMUC.

Electron emission from tungsten surface induced by neon ions

Science.gov (United States)

Xu, Zhongfeng; Zeng, Lixia; Zhao, Yongtao; Cheng, Rui; Zhang, Xiaoan; Ren, Jieru; Zhou, Xianming; Wang, Xing; Lei, Yu; Li, Yongfeng; Yu, Yang; Liu, Xueliang; Xiao, Guoqing; Li, Fuli

2014-04-01

The electron emission from W surface induced by Neq+ has been measured. For the same charge state, the electron yield gradually increases with the projectile velocity. Meanwhile, the effect of the potential energy of projectile has been found obviously. Our results give the critical condition for "trampoline effect".

Total cross-sections for single electron capture from H, He and H2 targets by impact of Be4+ and B5+ ions

International Nuclear Information System (INIS)

Busnengo, H.F.; Rivarola, R.D.; Universidad Nacional de Rosario; Rosario Univ. Nacional

1996-01-01

Single electron capture from H, He and H 2 targets by impact of Be 4+ and B 5+ projectiles is studied for intermediate and high collision energies. Total cross-sections are calculated using the continuum distorted wave-eikonal final state model. Theoretical results corresponding to capture to selective final bound states and to all final states are presented for impact energies ranging from 50 keV/amu to 3 MeV/amu. A comparison with available experimental data is also shown. (orig.)

Imaging femtosecond laser-induced electronic excitation in glass

International Nuclear Information System (INIS)

Mao Xianglei; Mao, Samuel S.; Russo, Richard E.

2003-01-01

While substantial progress has been achieved in understanding laser ablation on the nanosecond and picosecond time scales, it remains a considerable challenge to elucidate the underlying mechanisms during femtosecond laser material interactions. We present experimental observations of electronic excitation inside a wide band gap glass during single femtosecond laser pulse (100 fs, 800 nm) irradiation. Using a femtosecond time-resolved imaging technique, we measured the evolution of a laser-induced electronic plasma inside the glass and calculated the electron number density to be on the order of 10 19 cm -3

Electron-beam-induced fracture of Kevlar single fibers

International Nuclear Information System (INIS)

Dickinson, J.T.; Jensen, L.C.; Klakken, M.L.

1986-01-01

We examine the unique situation involving the exposure of polymers to both electron bombardment and mechanical stress. Under certain conditions, crack formation, crack growth, and fracture can occur due to this combination of stimuli. These studies relate to the performance of a number of materials under hostile environments such as space, plasma, and propulsion systems. In this paper we present our initial measurements on the response of single Kevlar fibers loaded in tension to bombardment by 3-keV electrons. We present evidence that the resulting electron-beam-induced fracture is due to bond breaking

Electron capture detection of sulphur gases in carbon dioxide at the parts-per-billion level

International Nuclear Information System (INIS)

Pick, M.E.

1979-01-01

A gas chromatograph with an electron capture detector has been used to determine sulphur gases in CO 2 at the parts-per-billion level, with particular application to the analysis of coolant from CO 2 cooled nuclear reactors. For COS, CS 2 , CH 3 SH, H 2 S and (CH 3 ) 2 S 2 the detector has a sensitivity comparable with the more commonly used flame photometric detector, but it is much less sensitive towards (CH 3 ) 2 S and thiophene. In addition, the paper describes a simple method for trapping sulphur gases which might enable detection of sub parts-per-billion levels of sulphur compounds. (Auth.)

Comparison between the mechanical and radiative electron-capture processes at high energies

International Nuclear Information System (INIS)

Gonzalez, A.D.; Miraglia, J.E.

1984-01-01

The ground-state--ground-state mechanical and radiative electron-capture processes are studied at very high, but not relativistic, projectile velocities. Three-body calculations were carried out with use of the continuum distorted-wave theoretical method for both processes. Total cross sections and final-atom angular distributions were computed, and the importance of each mechanism examined. For total cross sections, the numerical results reaffirm that the radiative process is the predominant mechanism at very high projectile energies. For a given incident charge, the range of projectile energies in which the nonrelativistic radiative mechanism is the most important decreases as the target charge increases. It is found that the radiative mechanism produces a very sharp final-atom angular distribution in the forward direction. When both processes, the radiative and mechanical, give the same total cross section, the calculations show that the radiative differential cross section in the forward direction is almost 2 orders of magnitude larger than the mechanical one

Simulation of wake potentials induced by relativistic proton bunches in electron clouds

Energy Technology Data Exchange (ETDEWEB)

Petrov, Fedor; Boine-Frankenheim, Oliver; Weiland, Thomas [Technische Universitaet Darmstadt (Germany). Institut fuer Theorie Elektromagnetischer Felder (TEMF)

2012-07-01

Electron clouds limit the intensity of modern high intensity hadron accelerators. Presently electron clouds are the main limiting factor for the LHC operation with 25 ns bunch trains. The bunches passing through an electron cloud induce a wake field. When the electron cloud density exceeds a certain threshold beam instabilities occur. The presence of electron clouds results in a shift of the synchronous phase, which increases if the bunch spacing is reduced. For LHC and SPS conditions we compare the longitudinal electron cloud wake potentials and stopping powers obtained using a simplified 2D electrostatic Particle-in-Cell code with fully electromagnetic simulations using VORPAL. In addition we analyze the wake fields induced by displaced or tilted bunches.

Electron capture by He2+ ions in collisions with H and H2 at impact energies below 10 keV

International Nuclear Information System (INIS)

Nutt, W.L.; McCullough, R.W.; Brady, K.; Shah, M.B.; Gilbody, H.B.

1978-01-01

Total cross sections for the process He 2+ + H(1s) → He + (Σn, 1) + H + involving capture into all final bound states of He + have been determined for 3 He 2+ ions in the range 1.5-9.0 keV using a furnace-target technique previously employed for similar measurements at higher impact energies. Measured cross sections are considerably smaller than those measured previously by Fite et al (Proc. R.Soc.; A268:527 (1962)) and are in better accord with recent theoretical estimates. A likely explanation for the discrepancy is given in terms of the corresponding cross sections for electron capture in He 2+ -H 2 collisions which have also been determined. (author)

5th International Workshop on Desorption Induced by Electronic Transitions

CERN Document Server

Jennison, Dwight R; Stechel, Ellen B; DIET V; Desorption induced by electronic transitions

1993-01-01

This volume in the Springer Series on Surface Sciences presents a recent account of advances in the ever-broadening field of electron-and photon-stimulated sur­ face processes. As in previous volumes, these advances are presented as the proceedings of the International Workshop on Desorption Induced by Electronic Transitions; the fifth workshop (DIET V) was held in Taos, New Mexico, April 1-4, 1992. It will be abundantly clear to the reader that "DIET" is not restricted to desorption, but has for several years included photochemistry, non-thermal surface modification, exciton self-trapping, and many other phenomena that are induced by electron or photon bombardment. However, most stimulated surface processes do share a common physics: initial electronic excitation, localization of the excitation, and conversion of electronic energy into nuclear kinetic energy. It is the rich variation of this theme which makes the field so interesting and fruitful. We have divided the book into eleven parts in orde...

3 to 15 keV Ar+ induced Auger electron emission from Si and Ar

International Nuclear Information System (INIS)

Kempf, J.; Kaus, G.

1977-01-01

Ar + induced Auger electrons from Si and Ar were investigated at bombardment energies between 3-15 keV and target currents of a few μA. The Auger electron yields were compared with secondary ion yields of Si and Ar by simultaneous SIMS-AES measurements. In the ion induced Auger spectra of Si five Auger peaks and in the Ar spectra three Auger peaks were observed. The ion induced Auger electron yield of Si and Ar were found to be strongly dependent upon the primary ion energy. 'Bulk like' and 'atomic like' Auger transitions of ion induced Auger electrons of Si were observed. (orig.) [de

Gene-specific characterization of human histone H2B by electron capture dissociation.

Science.gov (United States)

Siuti, Nertila; Roth, Michael J; Mizzen, Craig A; Kelleher, Neil L; Pesavento, James J

2006-02-01

The basis set of protein forms expressed by human cells from the H2B gene family was determined by Top Down Mass Spectrometry. Using Electron Capture Dissociation for MS/MS of H2B isoforms, direct evidence for the expression of unmodified H2B.Q, H2B.A, H2B.K/T, H2B.J, H2B.E, H2B.B, H2B.F, and monoacetylated H2B.A was obtained from asynchronous HeLa cells. H2B.A was the most abundant form, with the overall expression profile not changing significantly in cells arrested in mitosis by colchicine or during mid-S, mid-G2, G2/M, and mid-G1 phases of the cell cycle. Modest hyperacetylation of H2B family members was observed after sodium butyrate treatment.

Electron emission from tungsten surface induced by neon ions

International Nuclear Information System (INIS)

Xu, Zhongfeng; Zeng, Lixia; Zhao, Yongtao; Liu, Xueliang; Xiao, Guoqing; Li, Fuli; Cheng, Rui; Zhang, Xiaoan; Ren, Jieru; Zhou, Xianming; Wang, Xing; Lei, Yu; Li, Yongfeng; Yu, Yang

2014-01-01

The electron emission from W surface induced by Ne q+ has been measured. For the same charge state, the electron yield gradually increases with the projectile velocity. Meanwhile, the effect of the potential energy of projectile has been found obviously. Our results give the critical condition for ''trampoline effect''

Fast electrons from multi-electron dynamics in xenon clusters induced by inner-shell ionization

International Nuclear Information System (INIS)

Bostedt, Christoph; Thomas, Heiko; Hoener, Matthias; Moeller, Thomas; Saalmann, Ulf; Georgescu, Ionut; Gnodtke, Christian; Rost, Jan-Michael

2010-01-01

Fast electrons emitted from xenon clusters in strong femtosecond 90 eV pulses have been measured at the Free-electron Laser in Hamburg (FLASH). Energy absorption occurs mainly through atomic inner-shell photo-ionization. Photo-electrons are trapped in the strong Coulomb potential of the cluster ions and form a non-equilibrium plasma with supra-atomic density. Its equilibration through multiple energy-exchanging collisions within the entire cluster volume produces electrons with energies well beyond the dominant emission line of atomic xenon. Here, in contrast to traditional low-frequency laser plasma heating, the plasma gains energy from electrons delivered through massive single-photon excitation from bound states. Electron emission induced by thermalization of a non-equilibrium plasma is expected to be a general phenomenon occurring for strong atomic x-ray absorption in extended systems.

Electron beam induced electronic transport in alkyl amine-intercalated VOx nanotubes

International Nuclear Information System (INIS)

O'Dwyer, C.; Lavayen, V.; Clavijo-Cedeno, C.; Torres, C.M.S.

2008-01-01

The electron beam induced electronic transport in primary alkyl amine-intercalated V 2 O 5 nanotubes is investigated where the organic amine molecules are employed as molecular conductive wires to an aminosilanized substrate surface and contacted to Au interdigitated electrode contacts. The results demonstrate that the high conductivity of the nanotubes is related to the non-resonant tunnelling through the amine molecules and a reduced polaron hopping conduction through the vanadium oxide itself. Both nanotube networks and individual nanotubes exhibit similarly high conductivities where the minority carrier transport is bias dependent and nanotube diameter invariant. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Simultaneous measurement of neutron-induced fission and capture cross sections for {sup 241}Am at neutron energies below fission threshold

Energy Technology Data Exchange (ETDEWEB)

Hirose, K., E-mail: hirose.kentaro@jaea.go.jp [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Nishio, K.; Makii, H.; Nishinaka, I.; Ota, S. [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Nagayama, T. [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Graduate School of Science and Engineering, Ibaraki University, Mito 310-0056 (Japan); Tamura, N. [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Goto, S. [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Andreyev, A.N. [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Vermeulen, M.J. [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Gillespie, S.; Barton, C. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Kimura, A.; Harada, H. [Nuclear Science and Engineering Center, JAEA, Tokai, Ibaraki 319-1195 (Japan); Meigo, S. [J-PARC Center, JAEA, Tokai, Ibaraki 319-1195 (Japan); Chiba, S. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Tokyo 152-8550 (Japan); Ohtsuki, T. [Research Reactor Institute, Kyoto University, Kumatori-cho S' ennangun,Osaka 590-0494 (Japan)

2017-06-01

Fission and capture reactions were simultaneously measured in the neutron-induced reactions of {sup 241}Am at the spallation neutron facility of the Japan Proton Accelerator Research Complex (J-PARC). Data for the neutron energy range of E{sub n}=0.1–20 eV were taken with the TOF method. The fission events were observed by detecting prompt neutrons accompanied by fission using liquid organic scintillators. The capture reaction was measured by detecting γ rays emitted in the deexcitation of the compound nuclei using the same detectors, where the prompt fission neutrons and capture γ rays were separated by a pulse shape analysis. The cross sections were obtained by normalizing the relative yields at the first resonance to evaluations or other experimental data. The ratio of the fission to capture cross sections at each resonance is compared with those from an evaluated nuclear data library and other experimental data. Some differences were found between the present values and the library/literature values at several resonances.

Electron dropout echoes induced by interplanetary shock: Van Allen Probes observations

International Nuclear Information System (INIS)

Hao, Y. X.; Zong, Q.-G.; Zhou, X.-Z.; Fu, S. Y.; Rankin, R.

2016-01-01

On 23 November 2012, a sudden dropout of the relativistic electron flux was observed after an interplanetary shock arrival. The dropout peaks at ~1 MeV and more than 80% of the electrons disappeared from the drift shell. Van Allen twin Probes observed a sharp electron flux dropout with clear energy dispersion signals. The repeating flux dropout and recovery signatures, or “dropout echoes”, constitute a new phenomenon referred to as a “drifting electron dropout” with a limited initial spatial range. The azimuthal range of the dropout is estimated to be on the duskside, from ~1300 to 0100 LT. We then conclude that the shock-induced electron dropout is not caused by the magnetopause shadowing. Furthermore, the dropout and consequent echoes suggest that the radial migration of relativistic electrons is induced by the strong dusk-dawn asymmetric interplanetary shock compression on the magnetosphere.

Capture from pair production as a beam loss mechanism for heavy ions at RHIC

International Nuclear Information System (INIS)

Feinberg, B.; Belkacem, A.; Claytor, N.; Dinneen, T.; Gould, H.

1997-05-01

Electron capture from electron-positron pair production is predicted to be a major source of beam loss for the heaviest ions at RHIC. Achieving the highest luminosity thus requires an understanding of the capture process. The authors report measurements of this process at Brookhaven National Laboratory's AGS using 10.8 GeV/nucleon Au 79+ projectiles on Au targets. Capture from pair production is a process in which the very high electromagnetic field involved in the collision of two relativistic heavy ions results in the production of an electron-positron pair with the capture of the electron by one of the ions. There are many theoretical papers published on capture from pair production with discrepancies between predicted cross sections. The experimental results are compared to theory and to previous experiments at 1 GeV/nucleon. The implications of extrapolations to RHIC energies are presented

Radiation-induced electron paramagnetic resonance signal and soybean isoflavones content

International Nuclear Information System (INIS)

Oliveira, Marcos R.R. de; Mandarino, José M.G.; Mastro, Nelida L. del

2012-01-01

Electron Paramagnetic Resonance (EPR) is a well-known spectroscopic technique that detects paramagnetic centers and can detect free radicals with high sensitivity. In food, free radicals can be generated by several commonly used industrial processes, such as radiosterilization or heat treatment. EPR spectroscopy is used to detect radioinduced free radicals in food. In this work the relation between EPR signal induced by gamma irradiation treatment and soybean isoflavones content was investigated. Present results did not show correlation between total isoflavones content and the EPR signal. Nevertheless, some isoflavone contents had a negative correlation with the radiation-induced EPR signal. - Highlights: ► Electron Paramagnetic Resonance (EPR) detects free radicals. ► Ionizing radiation as free radicals inducer. ► Total soybean isoflvones do not correlate with radiation-induced EPR intensity but a soybean glucosyl glucoside isoflavone does.

Electron and photon-beam induced reactions of adsorbed disilane: Low-temperature thin-film growth

International Nuclear Information System (INIS)

Bozso, F.; Avouris, Ph.

1991-01-01

Electrons and photons of sufficient energy can cause fragmentation and desorption of adsorbed molecules or fragments of them, by inducing electronic excitations to dissociative states. The surface species after such excitations are mostly of highly reactive radical character, which readily react with the substrate and with other molecular or radical species in the adsorbed layer. This paper discusses the adsorption, thermal and electron/photon-beam induced reactions of disilane, oxygen and ammonia on Si(111)-7x7, and the electron/photon-induced growth of silicon, silicon dioxide and silicon nitride films at 100K

Spin-polarized electron capture for the Na+3He2+ system at a 3He2+ impact energy of 5.33--9.33 keV/amu

International Nuclear Information System (INIS)

Tanaka, M.; Shimakura, N.; Ohshima, T.; Katori, K.; Fujiwara, M.; Ogata, H.; Kondo, M.

1994-01-01

3 He + atomic polarizations following the spin-polarized electron capture process for the N rvec a(3s)+ 3 He 2+ system were measured at 3 He 2+ impact energies from 5.33 to 9.33 keV/amu. The magnitude of the 3 He + atomic polarizations was deduced from the 3 He + nuclear polarization measured by means of beam-foil spectroscopy. The observed polarization transfer coefficient P T defined by the ratio of the 3 He + atomic polarization to the sodium one showed a pronounced reduction from unity, which was qualitatively explained by the prediction of a simple cascade photon decay model. Evidence for a further reduction of P T from the above model and a possible impact energy dependence of P T suggested an excessive depolarization due to the presence of the collision alignment parameter A 0 col of 3 He + formed by the electron capture process. In order to see this more closely, the observed P T 's were examined theoretically using the semiclassical impact parameter method, in which an 18-state molecular expansion was employed, and atomic-type electron translation effects were rigorously taken into account. Ensuring that both the absolute values and the impact energy dependence of the observed capture cross sections were remarkably well reproduced by the calculations in which the states up to 4f in 3 He + were introduced, it was demonstrated that the calculated results for P T qualitatively reproduced not only the absolute values of the observed P T 's but also their gentle decrease with increasing impact energy. Production of nuclear polarizations resulting from the polarized electron capture processes between multicharged heavy ions and alkaline-earth-metal atoms is an example of one use of the future project of universal polarized heavy-ion sources

Exploratory investigations of hypervelocity intact capture spectroscopy

Science.gov (United States)

Tsou, P.; Griffiths, D. J.

1993-01-01

The ability to capture hypervelocity projectiles intact opens a new technique available for hypervelocity research. A determination of the reactions taking place between the projectile and the capture medium during the process of intact capture is extremely important to an understanding of the intact capture phenomenon, to improving the capture technique, and to developing a theory describing the phenomenon. The intact capture of hypervelocity projectiles by underdense media generates spectra, characteristic of the material species of projectile and capture medium involved. Initial exploratory results into real-time characterization of hypervelocity intact capture techniques by spectroscopy include ultra-violet and visible spectra obtained by use of reflecting gratings, transmitting gratings, and prisms, and recorded by photographic and electronic means. Spectrometry proved to be a valuable real-time diagnostic tool for hypervelocity intact capture events, offering understanding of the interactions of the projectile and the capture medium during the initial period and providing information not obtainable by other characterizations. Preliminary results and analyses of spectra produced by the intact capture of hypervelocity aluminum spheres in polyethylene (PE), polystyrene (PS), and polyurethane (PU) foams are presented. Included are tentative emission species identifications, as well as gray body temperatures produced in the intact capture process.

Water Capture Device Signal Integration Board

Science.gov (United States)

Chamberlin, Kathryn J.; Hartnett, Andrew J.

2018-01-01

I am a junior in electrical engineering at Arizona State University, and this is my second internship at Johnson Space Center. I am an intern in the Command and Data Handling Branch of Avionics Division (EV2), my previous internship was also in EV2. During my previous internship I was assigned to the Water Capture Device payload, where I designed a prototype circuit board for the electronics system of the payload. For this internship, I have come back to the Water Capture Device project to further the work on the electronics design I completed previously. The Water Capture Device is an experimental payload to test the functionality of two different phase separators aboard the International Space Station (ISS). A phase separator sits downstream of a condensing heat exchanger (CHX) and separates the water from the air particles for environmental control on the ISS. With changing CHX technology, new phase separators are required. The goal of the project is to develop a test bed for the two phase separators to determine the best solution.

Radiative muon capture on hydrogen

International Nuclear Information System (INIS)

Bertl, W.; Ahmad, S.; Chen, C.Q.; Gumplinger, P.; Hasinoff, M.D.; Larabee, A.J.; Sample, D.G.; Schott, W.; Wright, D.H.; Armstrong, D.S.; Blecher, M.; Azuelos, G.; Depommier, P.; Jonkmans, G.; Gorringe, T.P.; Henderson, R.; Macdonald, J.A.; Poutissou, J.M.; Poutissou, R.; Von Egidy, T.; Zhang, N.S.; Robertson, B.D.

1992-01-01

The radiative capture of negative muons by protons can be used to measure the weak induced pseudoscalar form factor. Brief arguments why this method is preferable to ordinary muon capture are given followed by a discussion of the experimental difficulties. The solution to these problems as attempted by experiment no. 452 at TRIUMF is presented together with preliminary results from the first run in August 1990. An outlook on the expected final precision and the experimental schedule is also given. (orig.)

Phantom experiment of depth-dose distributions for gadolinium neutron capture therapy

International Nuclear Information System (INIS)

Matsumoto, T.; Kato, K.; Sakuma, Y.; Tsuruno, A.; Matsubayashi, M.

1993-01-01

Depth-dose distributions in a tumor simulated phantom were measured for thermal neutron flux, capture gamma-ray and internal conversion electron dose rates for gadolinium neutron capture therapy. The results show that (i) a significant dose enhancement can be achieved in the tumor by capture gamma-rays and internal conversion electrons but the dose is mainly due to capture gamma-rays from the Gd(n, γ) reactions, therefore, is not selective at the cellular level, (ii) the dose distribution was a function of strongly interrelated parameters such as gadolinium concentrations, tumor site and neutron beam size (collimator aperture size), and (iii) the Gd-NCT by thermal neutrons appears to be a potential for treatment of superficial tumor. (author)

Activity Induces Fmr1-Sensitive Synaptic Capture of Anterograde Circulating Neuropeptide Vesicles.

Science.gov (United States)

Cavolo, Samantha L; Bulgari, Dinara; Deitcher, David L; Levitan, Edwin S

2016-11-16

Synaptic neuropeptide and neurotrophin stores are maintained by constitutive bidirectional capture of dense-core vesicles (DCVs) as they circulate in and out of the nerve terminal. Activity increases DCV capture to rapidly replenish synaptic neuropeptide stores following release. However, it is not known whether this is due to enhanced bidirectional capture. Here experiments at the Drosophila neuromuscular junction, where DCVs contain neuropeptides and a bone morphogenic protein, show that activity-dependent replenishment of synaptic neuropeptides following release is evident after inhibiting the retrograde transport with the dynactin disruptor mycalolide B or photobleaching DCVs entering a synaptic bouton by retrograde transport. In contrast, photobleaching anterograde transport vesicles entering a bouton inhibits neuropeptide replenishment after activity. Furthermore, tracking of individual DCVs moving through boutons shows that activity selectively increases capture of DCVs undergoing anterograde transport. Finally, upregulating fragile X mental retardation 1 protein (Fmr1, also called FMRP) acts independently of futsch/MAP-1B to abolish activity-dependent, but not constitutive, capture. Fmr1 also reduces presynaptic neuropeptide stores without affecting activity-independent delivery and evoked release. Therefore, presynaptic motoneuron neuropeptide storage is increased by a vesicle capture mechanism that is distinguished from constitutive bidirectional capture by activity dependence, anterograde selectivity, and Fmr1 sensitivity. These results show that activity recruits a separate mechanism than used at rest to stimulate additional synaptic capture of DCVs for future release of neuropeptides and neurotrophins. Synaptic release of neuropeptides and neurotrophins depends on presynaptic accumulation of dense-core vesicles (DCVs). At rest, DCVs are captured bidirectionally as they circulate through Drosophila motoneuron terminals by anterograde and retrograde

Radiative muon capture and renormalization of the induced pseudoscalar coupling constant in nuclei

International Nuclear Information System (INIS)

Hasinoff, M.D.; Armstrong, D.S.; Azuelos, G.

1992-08-01

Radiative Muon Capture (RMC), μ - Z → ν μ (Z - 1)γ, is a weak semi-leptonic process which is particularly sensitive to the induced pseudoscalar coupling constant, g p , of the weak hadronic current. After a brief introduction and review of the general theoretical background relevant to RMC, the most recent data from TRIUMF and PSI are presented and compared to the latest theoretical calculations. The extracted g p values are compared to the PCAC prediction for RMC on a free proton to determine whether or not there is any significant renormalization of g p inside the nuclear medium. A progress report on the TRIUMF RMC experiment on hydrogen is also presented. refs., 12 figs., 3 tabs

The effect of electron range on electron beam induced current collection and a simple method to extract an electron range for any generation function

International Nuclear Information System (INIS)

Lahreche, A.; Beggah, Y.; Corkish, R.

2011-01-01

The effect of electron range on electron beam induced current (EBIC) is demonstrated and the problem of the choice of the optimal electron ranges to use with simple uniform and point generation function models is resolved by proposing a method to extract an electron range-energy relationship (ERER). The results show that the use of these extracted electron ranges remove the previous disagreement between the EBIC curves computed with simple forms of generation model and those based on a more realistic generation model. The impact of these extracted electron ranges on the extraction of diffusion length, surface recombination velocity and EBIC contrast of defects is discussed. It is also demonstrated that, for the case of uniform generation, the computed EBIC current is independent of the assumed shape of the generation volume. -- Highlights: → Effect of electron ranges on modeling electron beam induced current is shown. → A method to extract an electron range for simple form of generation is proposed. → For uniform generation the EBIC current is independent of the choice of it shape. → Uses of the extracted electron ranges remove some existing literature ambiguity.

Electron-induced chemistry in microhydrated sulfuric acid clusters

Science.gov (United States)

Lengyel, Jozef; Pysanenko, Andriy; Fárník, Michal

2017-11-01

We investigate the mixed sulfuric acid-water clusters in a molecular beam experiment with electron attachment and negative ion mass spectrometry and complement the experiment by density functional theory (DFT) calculations. The microhydration of (H2SO4)m(H2O)n clusters is controlled by the expansion conditions, and the electron attachment yields the main cluster ion series (H2SO4)m(H2O)nHSO4- and (H2O)nH2SO4-. The mass spectra provide an experimental evidence for the onset of the ionic dissociation of sulfuric acid and ion-pair (HSO4- ṡ ṡ ṡ H3O+) formation in the neutral H2SO4(H2O)n clusters with n ≥ 5 water molecules, in excellent agreement with the theoretical predictions. In the clusters with two sulfuric acid molecules (H2SO4)2(H2O)n this process starts as early as n ≥ 2 water molecules. The (H2SO4)m(H2O)nHSO4- clusters are formed after the dissociative electron attachment to the clusters containing the (HSO4- ṡ ṡ ṡ H3O+) ion-pair structure, which leads to the electron recombination with the H3O+ moiety generating H2O molecule and the H-atom dissociation from the cluster. The (H2O)nH2SO4- cluster ions point to an efficient caging of the H atom by the surrounding water molecules. The electron-energy dependencies exhibit an efficient electron attachment at low electron energies below 3 eV, and no resonances above this energy, for all the measured mass peaks. This shows that in the atmospheric chemistry only the low-energy electrons can be efficiently captured by the sulfuric acid-water clusters and converted into the negative ions. Possible atmospheric consequences of the acidic dissociation in the clusters and the electron attachment to the sulfuric acid-water aerosols are discussed.

Dynamic correlation of photo-excited electrons: Anomalous levels induced by light–matter coupling

Energy Technology Data Exchange (ETDEWEB)

Jiang, Xiankai [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Huai, Ping, E-mail: huaiping@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China); Song, Bo, E-mail: bosong@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China)

2014-04-01

Nonlinear light–matter coupling plays an important role in many aspects of modern physics, such as spectroscopy, photo-induced phase transition, light-based devices, light-harvesting systems, light-directed reactions and bio-detection. However, excited states of electrons are still unclear for nano-structures and molecules in a light field. Our studies unexpectedly present that light can induce anomalous levels in the electronic structure of a donor–acceptor nanostructure with the help of the photo-excited electrons transferring dynamically between the donor and the acceptor. Furthermore, the physics underlying is revealed to be the photo-induced dynamical spin–flip correlation among electrons. These anomalous levels can significantly enhance the electron current through the nanostructure. These findings are expected to contribute greatly to the understanding of the photo-excited electrons with dynamic correlations, which provides a push to the development and application of techniques based on photosensitive molecules and nanostructures, such as light-triggered molecular devices, spectroscopic analysis, bio-molecule detection, and systems for solar energy conversion.

Auger electron spectroscopy analysis of high metal content micro-structures grown by electron beam induced deposition

International Nuclear Information System (INIS)

Cicoira, F.; Hoffmann, P.; Olsson, C.O.A.; Xanthopoulos, N.; Mathieu, H.J.; Doppelt, P.

2005-01-01

An auger electron spectroscopy study was carried out on Rh-containing micro-structures grown by electron beam induced deposition (EBID) of the iso-structural and iso-electronic precursors [RhCl(PF 3 ) 2 ] 2 and [RhCl(CO) 2 ] 2 . A material containing between 55 and 60 at.% Rh was obtained from both precursors. The chemical composition of structures grown from the two different precursors indicates a similar decomposition mechanism. Deposits grown from [RhCl(PF 3 ) 2 ] 2 showed a chemical composition independent of electron energy and electron dose in the investigated range of conditions

Physical design of the positron induced auger electron spectrometer

International Nuclear Information System (INIS)

Qin Xiubo; Jiang Xiaopan; Wang Ping; Yu Runsheng; Wang Baoyi; Wei Long

2009-01-01

Positron Annihilation Induced Auger Electron Spectroscopy (PAES) has several advantages over those excited by X-rays, high energy electrons or neutrons, such as excellent surface selectivity, high signal-to-noise ratio, low radiation damage,etc. A physical design of time of flight PAES (TOF-PAES) apparatus based on the Beijing Intense Slow Positron Beam (BIPB) is described in this paper. The positrons and electrons are transported in a 4 x 10 -3 T uniform magnetic field, and the gradient of magnetic field is designed to pluralize the Auger electrons emitted with 2π angle. The Auger electron energy is adjusted by a Faraday cage to optimize the energy resolution,which can be better than 2 eV. (authors)

Boron neutron capture therapy induces cell cycle arrest and DNA fragmentation in murine melanoma cells

Energy Technology Data Exchange (ETDEWEB)

Faiao-Flores, F. [Biochemical and Biophysical Laboratory, Butantan Institute, 1500 Vital Brasil Avenue, Sao Paulo (Brazil)] [Faculty of Medicine, University of Sao Paulo, 455 Doutor Arnaldo Avenue, Sao Paulo (Brazil); Coelho, P.R.P. [Institute for Nuclear and Energy Research, 2242 Lineu Prestes Avenue, Sao Paulo (Brazil); Arruda-Neto, J. [Physics Institute, University of Sao Paulo, 187 Matao Street, Sao Paulo (Brazil)] [FESP, Sao Paulo Engineering School, 5520 Nove de Julho Avenue, Sao Paulo (Brazil); Maria, Durvanei A., E-mail: durvaneiaugusto@yahoo.br [Biochemical and Biophysical Laboratory, Butantan Institute, 1500 Vital Brasil Avenue, Sao Paulo (Brazil)

2011-12-15

The melanoma is a highly lethal skin tumor, with a high incidence. Boron Neutron Capture Therapy (BNCT) is a radiotherapy which combines Boron with thermal neutrons, constituting a binary system. B16F10 melanoma and L929 fibroblasts were treated with Boronophenylalanine and irradiated with thermal neutron flux. The electric potential of mitochondrial membrane, cyclin D1 and caspase-3 markers were analyzed. BNCT induced a cell death increase and cyclin D1 amount decreased only in B16F10 melanoma. Besides, there was not caspase-3 phosphorylation.

Exploring the use of tablet computer-based electronic data capture system to assess patient reported measures among patients with chronic kidney disease: a pilot study.

Science.gov (United States)

Wong, Dorothy; Cao, Shen; Ford, Heather; Richardson, Candice; Belenko, Dmitri; Tang, Evan; Ugenti, Luca; Warsmann, Eleanor; Sissons, Amanda; Kulandaivelu, Yalinie; Edwards, Nathaniel; Novak, Marta; Li, Madeline; Mucsi, Istvan

2017-12-06

Collecting patient reported outcome measures (PROMs) via computer-based electronic data capture system may improve feasibility and facilitate implementation in clinical care. We report our initial experience about the acceptability of touch-screen tablet computer-based, self-administered questionnaires among patients with chronic kidney disease (CKD), including stage 5 CKD treated with renal replacement therapies (RRT) (either dialysis or transplant). We enrolled a convenience sample of patients with stage 4 and 5 CKD (including patients on dialysis or after kidney transplant) in a single-centre, cross-sectional pilot study. Participants completed validated questionnaires programmed on an electronic data capture system (DADOS, Techna Inc., Toronto) on tablet computers. The primary objective was to evaluate the acceptability and feasibility of using tablet-based electronic data capture in patients with CKD. Descriptive statistics, Fischer's exact test and multivariable logistic regression models were used for data analysis. One hundred and twenty one patients (55% male, mean age (± SD) of 58 (±14) years, 49% Caucasian) participated in the study. Ninety-two percent of the respondents indicated that the computer tablet was acceptable and 79% of the participants required no or minimal help for completing the questionnaires. Acceptance of tablets was lower among patients 70 years or older (75% vs. 95%; p = 0.011) and with little previous computer experience (81% vs. 96%; p = 0.05). Furthermore, a greater level of assistance was more frequently required by patients who were older (45% vs. 15%; p = 0.009), had lower level of education (33% vs. 14%; p = 0.027), low health literacy (79% vs. 12%; p = 0.027), and little previous experience with computers (52% vs. 10%; p = 0.027). Tablet computer-based electronic data capture to administer PROMs was acceptable and feasible for most respondents and could therefore be used to systematically assess PROMs

Electronic-excitation induced radiation damage in glasses

Energy Technology Data Exchange (ETDEWEB)

Vigouroux, J P

1985-01-01

In order to understand the microscopic nature of radiation induced defects in insulators, we have studied localization of negative and positive charges in amorphous and monocrystalline SiO2. The behaviour of these charges is linked to creation of point defects by electronic excitation. The role of intense electric fields under irradiation is pointed out.

Measurement of concentrations of {gamma}-ray emitters induced in the concrete shield of the JAERI electron linac facility

Energy Technology Data Exchange (ETDEWEB)

Endo, Akira; Kawasaki, Katsuya; Kikuchi, Masamitsu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Harada, Yasunori

1997-07-01

Measurement has been made to study distributions of {gamma}-ray emitters induced in the concrete shield of the JAERI electron linac facility. Core boring was carried out at seven positions to take samples from the concrete shield, and {gamma}-ray counting rates and {gamma}-ray spectra of these samples were measured with a NaI(Tl) detector and a Ge semiconductor detector, respectively. The following radionuclides were detected in the concrete samples: {sup 60}Co, {sup 134}Cs, {sup 152}Eu and {sup 154}Eu generated through thermal neutron capture reaction, and {sup 22}Na and {sup 54}Mn generated through nuclear reactions by bremsstrahlung and fast neutrons. The relation between the distributions of {gamma}-ray emitters, as a function of the depth of concrete, and the positions of core boring is discussed. (author)

Electron irradiation induced nanocrystal formation in Cu-borosilicate glass

Energy Technology Data Exchange (ETDEWEB)

Sabri, Mohammed Mohammed; Möbus, Günter, E-mail: g.moebus@sheffield.ac.uk [University of Sheffield, Department of Materials Science and Engineering (United Kingdom)

2016-03-15

Nanoscale writing of Cu nanoparticles in glasses is introduced using focused electron irradiation by transmission electron microscopy. Two types of copper borosilicate glasses, one with high and another with low Cu loading, have been tested at energies of 200–300 keV, and formation of Cu nanoparticles in a variety of shapes and sizes using different irradiation conditions is achieved. Electron energy loss spectroscopy analysis, combined with high-resolution transmission electron microscopy imaging, confirmed the irradiation-induced precipitated nanoparticles as metallic, while furnace annealing of the glass triggered dendrite-shaped particles of copper oxide. Unusual patterns of nanoparticle rings and chains under focused electron beam irradiation are also presented. Conclusively, electron beam patterning of Cu-loaded glasses is a promising alternative route to well-established femtosecond laser photoreduction of Cu ions in glass.

Laser-induced electron--ion recombination used to study enhanced spontaneous recombination during electron cooling

International Nuclear Information System (INIS)

Schramm, U.; Wolf, A.; Schuess ler, T.; Habs, D.; Schwalm, D.; Uwira, O.; Linkemann, J.; Mueller, A.

1997-01-01

Spontaneous recombination of highly charged ions with free electrons in merged velocity matched electron and ion beams has been observed in earlier experiments to occur at rates significantly higher than predicted by theoretical estimates. To study this enhanced spontaneous recombination, laser induced recombination spectra were measured both in velocity matched beams and in beams with well defined relative velocities, corresponding to relative electron-ion detuning energies ranging from 1 meV up to 6.5 meV where the spontaneous recombination enhancement was found to be strongly reduced. Based on a comparison with simplified calculations, the development of the recombination spectra for decreasing detuning energies indicates additional contributions at matched velocities which could be related to the energy distribution of electrons causing the spontaneous recombination rate enhancement

Review of fission produce capture measurements at the Oak Ridge Electron Laser Accelerator (ORELA)

International Nuclear Information System (INIS)

Larson, D.C.; Macklin, R.L.

1992-01-01

The 40-meter capture system of R.L. Macklin at ORELA has been used to measure capture cross sections for over eighty isotopes between A = 75 and 161, the primary mass region of interest for fission products. This review outlines the primary features of the capture system, lists the isotopes measured and their references, and describes recent changes incorporated in the capture system

One-electron capture into Li-like autoionising N4+ (1s2ln'l') configurations by metastable N5+ (1s2s3S) multicharged ions in collisions with He and H2, observed by electron spectrometry at 3.4 keV amu-1

International Nuclear Information System (INIS)

Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.

1985-01-01

One-electron capture into N 4+ (1s2ln'l') configurations, with n'=2 to 4, has been observed by electron spectrometry when a N 5+ (1s2s 3 S) multicharged ion beam encounters an He or H 2 target, at low collision velocity (upsilon=0.37 au) within single-collision conditions. Contributions of other 1s2l metastable states and of the 1s 2 ground state may be disregarded. A small indication of two-electron capture by 1s2s 3 S ions into (1s2s 3 S)3l3l' configurations is also seen. (author)

Electron spectroscopy in the fundamental process of electron-nucleus bremsstrahlung

International Nuclear Information System (INIS)

Hillenbrand, Pierre-Michel

2013-07-01

Within the scope of this thesis the fundamental process of electron-nucleus bremsstrahlung was studied in inverse kinematics at the Experimental Storage Ring ESR at GSI. For the system U 88+ + N 2 at 90 MeV/u it was shown, that by using inverse kinematics coincidence measurements between the scattered electron and the emitted photon can be performed for the case, in which the incoming electron transfers almost all of its kinetic energy onto the emitted photon. The sensitivity to the fundamental process could be achieved by measuring triple differential cross sections as a function of the emission angle of the photon and the scattered electron as well as the energy of the scattered electron. The optics of the magnetic electron spectrometer used were thoroughly revised and optimized to the experimental requirements. Analyzing different coincidences in this collision system, it was possible to determine the contributions to the electron distribution arising from radiative electron capture to the projectile continuum, nonradiative electron capture to the projectile continuum, and electron loss to the projectile continuum. The experimental results of each of these processes were compared to theoretical calculations. The electron spectra for the radiative and the nonradiative electron capture to continuum clearly reproduce the opposite asymmetry predicted by theory. Furthermore electron spectra for collisions of U 28+ with different gases were measured.

On novel mechanisms of slow ion induced electron emission

International Nuclear Information System (INIS)

Eder, H.

2000-09-01

The present work has contributed in new ways to the field of slow ion induced electron emission. First, measurements of the total electron yield γ for impact of slow singly and multiply charged ions on atomically clean polycrystalline gold and graphite have been made. The respective yields were determined by current measurements and measurements of the electron number statistics. A new mechanism for kinetic emission (KE) below the so called 'classical threshold' was found and discussed. For a given ion species and impact velocity a slight decrease of the yields was found for ion charge state q = 1 toward 3, but no significant differences in KE yields for higher q values. Comparison of the results from gold and graphite showed overall similar behavior, but for C+ a relatively strong difference was observed and ascribed to more effective electron promotion in the C-C- than in the C-Au system. Secondly, for the very specific system H0 on LiF we investigated single electron excitation processes under grazing incidence conditions. In this way long-range interactions of hydrogen atoms with the ionic crystal surface could be probed. Position- and velocity-dependent electron production rates were found which indicate that an electron promotion mechanism is responsible for the observed electron emission. Thirdly, in order to investigate the importance of plasmon excitation and -decay in slow ion induced electron emission, measurements of electron energy distributions from impact of singly and doubly charged ions on poly- and monocrystalline aluminum surfaces were performed. From the results we conclude that direct plasmon excitation by slow ions occurs due to the potential energy of the projectile in a quasi-resonant fashion. The highest relative plasmon intensities were found for impact of 5 keV Ne+ on Al(111) with 5 % of the total yield. For impact of H + and H 2 + characteristical differences were observed for Al(111) and polycrystalline aluminum. We show that

Eikonal calculation of electron-capture cross sections in collisions of H atoms with fast projectiles

International Nuclear Information System (INIS)

Ho, T.S.; Lieber, M.; Chan, F.T.

1981-01-01

We have employed the eikonal method to calculate the cross section for the capture of an electron into an arbitrary nl subshell in collisions between hydrogen atoms and fast projectiles. the projectiles were protons, C 6+ , O 8+ , and Fe 24+ . The energy ranges considered were 20--100 keV in the proton case, and 40--200 keV per nucleon in the other cases. These projectiles were selected because of their importance in fusion plasmas. For the highly charged case of Fe 24+ we found that our formulas, while exact, involved a high degree of cancellation and produced unreliable numerical results, so that a numerical integration of the penultimate formula was substituted. In the proton case agreement with recent experimental data is excellent

Photon- and electron-induced surface voltage in electron spectroscopies on ZnSe(0 0 1)

International Nuclear Information System (INIS)

Cantoni, M.; Bertacco, R.; Brambilla, A.; Ciccacci, F.

2009-01-01

The surface band bending in ZnSe(0 0 1), as a function of the temperature, is investigated both in the valence band (by photoemission) and in the conduction band (by inverse photoemission and absorbed current spectroscopies). Two different mechanisms are invoked for interpreting the experimental data: the band bending due to surface states, and the surface voltage induced by the incident beam. While the latter is well known in photoemission (surface photovoltage), we demonstrate the existence of a similar effect in inverse photoemission and absorbed current spectroscopies, induced by the incident electrons instead of photons. These results point to the importance of considering the surface voltage effect even in electron-in techniques for a correct evaluation of the band bending.

Determination of nitrosourea compounds in brain tissue by gas chromatography and electron capture detection.

Science.gov (United States)

Hassenbusch, S J; Colvin, O M; Anderson, J H

1995-07-01

A relatively simple, high-sensitivity gas chromatographic assay is described for nitrosourea compounds, such as BCNU [1,3-bis(2-chloroethyl)-1-nitrosourea] and MeCCNU [1-(2-chloroethyl)-3-(trans-4-methylcyclohexyl)-1-nitrosourea], in small biopsy samples of brain and other tissues. After extraction with ethyl acetate, secondary amines in BCNU and MeCCNU are derivatized with trifluoroacetic anhydride. Compounds are separated and quantitated by gas chromatography using a capillary column with temperature programming and an electron capture detector. Standard curves of BCNU indicate a coefficient of variance of 0.066 +/- 0.018, a correlation coefficient of 0.929, and an extraction efficiency from whole brain of 68% with a minimum detectable amount of 20 ng in 5-10 mg samples. The assay has been facile and sensitive in over 1000 brain biopsy specimens after intravenous and intraarterial infusions of BCNU.

Kinetic electron emission from metal surfaces induced by impact of slow ions

Czech Academy of Sciences Publication Activity Database

Šroubek, Zdeněk; Lorinčík, Jan

-, č. 625 (2014), s. 7-9 ISSN 0039-6028 R&D Projects: GA MŠk(CZ) ME10086 Institutional support: RVO:67985882 Keywords : Ion induced kinetic electron emission * Electronic excitation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.925, year: 2014

New approach to K-electron-capture probabilities to the 437 and 384 keV levels in the decay of /sup 133/Ba

Energy Technology Data Exchange (ETDEWEB)

Singh, K; Sahota, H S [Punjabi Univ., Patiala (India). Dept. of Physics

1983-12-01

The K-electron-capture probabilities to the 437 and 384 keV levels in the decay of /sup 133/Ba have been determined from a measurement of gamma-ray intensities in conjunction with an analysis of the K x-ray-gamma-ray sum peaks. The results are independent of fluorescence yield and detector efficiency.

Spontaneous and stimulated emission induced by an electron, electron bunch, and electron beam in a plasma

International Nuclear Information System (INIS)

Kuzelev, M V; Rukhadze, A A

2008-01-01

Two fundamental mechanisms - the Cherenkov effect and anomalous Doppler effect - underlying the emission by an electron during its superluminal motion in medium are considered. Cherenkov emission induced by a single electron and a small electron bunch is spontaneous. In the course of spontaneous Cherenkov emission, the translational motion of an electron is slowed down and the radiation energy grows linearly with time. As the number of radiating electrons increases, Cherenkov emission becomes stimulated. Stimulated Cherenkov emission represents a resonance beam instability. This emission process is accompanied by longitudinal electron bunching in the beam or by the breaking of an electron bunch into smaller bunches, in which case the radiation energy grows exponentially with time. In terms of the longitudinal size L e of the electron bunch there is a transition region λ e 0 -1 between the spontaneous and stimulated Cherenkov effects, where λ is the average radiation wavelength, and δ 0 is the dimensionless (in units of the radiation frequency) growth rate of the Cherenkov beam instability. The range to the left of this region is dominated by spontaneous emission, whereas the range to the right of this region is dominated by stimulated emission. In contrast to the Vavilov-Cherenkov effect, the anomalous Doppler effect should always (even for a single electron) be considered as stimulated, because it can only be explained by accounting for the reverse action of the radiation field on the moving electron. During stimulated emission in conditions where anomalous Doppler effect shows itself, an electron is slowed down and spins up; in this case, the radiation energy grows exponentially with time. (reviews of topical problems)

Double electron capture in collisions of the helium-like ions N/sup 5+/, O/sup 6+/ and Ne/sup 8+/ with helium atoms

Energy Technology Data Exchange (ETDEWEB)

Boudjema, M.; Moretto-Capelle, P.; Bordenave-Montesquieu, A. and others

1989-03-28

A fitting procedure of 1s/sup 2/3l3l' lines observed in A/sup (z-2)+/(1s/sup 2/)+He collisions (Z = 7, 8 and 10), at 10 q keV collision energy (q = Z -2) and 10/sup 0/ observation angle, allows us to compare new theoretical positions and lifetimes, and experimental electron spectra. It is found that the spin conservation rule holds and that only singlet states are populated in these capture processes. As in N/sup 7+/ and O/sup 8+/ + He systems, capture into the highest angular momentum /sup 1/G state is favoured in O/sup 6+/ and Ne/sup 8+/ + He systems and accounts for 26% of the double capture at 10/sup 0/. In N/sup 5+/ + He, the L distribution is broader and no L value is clearly predominant.

Dynamics of RF captured cooled proton beams

International Nuclear Information System (INIS)

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 RF buckets were observed. Here we present the experimental facts, present a simple theory, and summarize computer simulation results which support the theory and facts

Reliability and corrosion induced degradation of electronic system

International Nuclear Information System (INIS)

Tapas, V.K.; Varde, P.V.

2014-01-01

This paper describe the corrosion induced degradation of electronic system failures due to environmental conditions such as humidity, temperature, ionic or organic contaminants, residuals; etc. which can accelerates as electrochemical reaction and causes corrosion of electronic components, Corrosive gases and water vapours from humid condition come into contact with the base metal results in buildup of various chemical reaction products. Ionic contamination responsible for electrochemical reaction, forms soluble complexes with metals, it can degrade the protective oxide film that forms on the positively biased metallization and/or lead to change in the local pH. Deterioration of metal components or electronic circuitry due to electrochemical migration needs to be controlled in order to reduce the corrosion. With explosive increase in demand and miniaturization in electronic system resulted in smaller components, closer spacing and thinner metallic path, it is expected that the corrosion and deterioration of electronic components may become cause or concern. This paper summarises the current understanding of chemistry behind possible causes of corrosion of electronic devices and its failure mechanism. (author)

Light-induced electronic non-equilibrium in plasmonic particles.

Science.gov (United States)

Kornbluth, Mordechai; Nitzan, Abraham; Seideman, Tamar

2013-05-07

We consider the transient non-equilibrium electronic distribution that is created in a metal nanoparticle upon plasmon excitation. Following light absorption, the created plasmons decohere within a few femtoseconds, producing uncorrelated electron-hole pairs. The corresponding non-thermal electronic distribution evolves in response to the photo-exciting pulse and to subsequent relaxation processes. First, on the femtosecond timescale, the electronic subsystem relaxes to a Fermi-Dirac distribution characterized by an electronic temperature. Next, within picoseconds, thermalization with the underlying lattice phonons leads to a hot particle in internal equilibrium that subsequently equilibrates with the environment. Here we focus on the early stage of this multistep relaxation process, and on the properties of the ensuing non-equilibrium electronic distribution. We consider the form of this distribution as derived from the balance between the optical absorption and the subsequent relaxation processes, and discuss its implication for (a) heating of illuminated plasmonic particles, (b) the possibility to optically induce current in junctions, and (c) the prospect for experimental observation of such light-driven transport phenomena.

Electron mobility variance in the presence of an electric field: Electron-phonon field-induced tunnel scattering

International Nuclear Information System (INIS)

Melkonyan, S.V.

2012-01-01

The problem of electron mobility variance is discussed. It is established that in equilibrium semiconductors the mobility variance is infinite. It is revealed that the cause of the mobility variance infinity is the threshold of phonon emission. The electron-phonon interaction theory in the presence of an electric field is developed. A new mechanism of electron scattering, called electron-phonon field-induced tunnel (FIT) scattering, is observed. The effect of the electron-phonon FIT scattering is explained in terms of penetration of the electron wave function into the semiconductor band gap in the presence of an electric field. New and more general expressions for the electron-non-polar optical phonon scattering probability and relaxation time are obtained. The results show that FIT transitions have principle meaning for the mobility fluctuation theory: mobility variance becomes finite.

Relativistic electron dropout echoes induced by interplanetary shocks

Science.gov (United States)

Schiller, Q.; Kanekal, S. G.; Boyd, A. J.; Baker, D. N.; Blake, J. B.; Spence, H. E.

2017-12-01

Interplanetary shocks that impact Earth's magnetosphere can produce immediate and dramatic responses in the trapped relativistic electron population. One well-studied response is a prompt injection capable of transporting relativistic electrons deep into the magnetosphere and accelerating them to multi-MeV energies. The converse effect, electron dropout echoes, are observations of a sudden dropout of electron fluxes observed after the interplanetary shock arrival. Like the injection echo signatures, dropout echoes can also show clear energy dispersion signals. They are of particular interest because they have only recently been observed and their causal mechanism is not well understood. In the analysis presented here, we show observations of electron drift echo signatures from the Relativistic Electron-Proton Telescope (REPT) and Magnetic Electron and Ion Sensors (MagEIS) onboard NASA's Van Allen Probes mission, which show simultaneous prompt enhancements and dropouts within minutes of the associated with shock impact. We show that the observations associated with both enhancements and dropouts are explained by the inward motion caused by the electric field impulse induced by the interplanetary shock, and either energization to cause the enhancement, or lack of a seed population to cause the dropout.

Laser induced ultrasonic phased array using full matrix capture data acquisition and total focusing method.

Science.gov (United States)

Stratoudaki, Theodosia; Clark, Matt; Wilcox, Paul D

2016-09-19

Laser ultrasonics is a technique where lasers are employed to generate and detect ultrasound. A data collection method (full matrix capture) and a post processing imaging algorithm, the total focusing method, both developed for ultrasonic arrays, are modified and used in order to enhance the capabilities of laser ultrasonics for nondestructive testing by improving defect detectability and increasing spatial resolution. In this way, a laser induced ultrasonic phased array is synthesized. A model is developed and compared with experimental results from aluminum samples with side drilled holes and slots at depths of 5 - 20 mm from the surface.

Isomer shift calibration of 61Ni by lifetime variation measurements in the electron capture decay of 57Ni

International Nuclear Information System (INIS)

Devillers, M.; Ladriere, J.

1987-01-01

In the present work, differential ionization chambers are used in order to measure the difference in the electron capture decay rate of 57 Ni nuclei in several pairs of different chemical compounds. Combination of these values with the corresponding Moessbauer isomer shifts provides a reliable experimental method to determine differences in electron densities at the nucleus. This allows to calibrate the isomer shift scale of the concerned nuclide. By using 61 Ni isomer shifts given in the literature, this work leads to the first experimental determination of the 61 Ni isomer shift calibration constant α = -(1.8±0.9).10 -3 .a 0 3 mm.s -1 . This corresponds to a change in the mean-square charge radius Δ 2 > = -(7.2±3.4).10 -4 fm 2 during the 67.4 keV Moessbauer transition of 61 Ni. (orig.)

Electron-induced chemistry in microhydrated sulfuric acid clusters

Directory of Open Access Journals (Sweden)

J. Lengyel

2017-11-01

Full Text Available We investigate the mixed sulfuric acid–water clusters in a molecular beam experiment with electron attachment and negative ion mass spectrometry and complement the experiment by density functional theory (DFT calculations. The microhydration of (H2SO4m(H2On clusters is controlled by the expansion conditions, and the electron attachment yields the main cluster ion series (H2SO4m(H2OnHSO4− and (H2OnH2SO4−. The mass spectra provide an experimental evidence for the onset of the ionic dissociation of sulfuric acid and ion-pair (HSO4−  ⋅  ⋅  ⋅  H3O+ formation in the neutral H2SO4(H2On clusters with n ≥ 5 water molecules, in excellent agreement with the theoretical predictions. In the clusters with two sulfuric acid molecules (H2SO42(H2On this process starts as early as n ≥ 2 water molecules. The (H2SO4m(H2OnHSO4− clusters are formed after the dissociative electron attachment to the clusters containing the (HSO4−  ⋅  ⋅  ⋅  H3O+ ion-pair structure, which leads to the electron recombination with the H3O+ moiety generating H2O molecule and the H-atom dissociation from the cluster. The (H2OnH2SO4− cluster ions point to an efficient caging of the H atom by the surrounding water molecules. The electron-energy dependencies exhibit an efficient electron attachment at low electron energies below 3 eV, and no resonances above this energy, for all the measured mass peaks. This shows that in the atmospheric chemistry only the low-energy electrons can be efficiently captured by the sulfuric acid–water clusters and converted into the negative ions. Possible atmospheric consequences of the acidic dissociation in the clusters and the electron attachment to the sulfuric acid–water aerosols are discussed.

Biomimetic Interfacial Electron-Induced Electrochemiluminesence.

Science.gov (United States)

Pu, Guiqiang; Zhang, Dongxu; Mao, Xiang; Zhang, Zhen; Wang, Huan; Ning, Xingming; Lu, Xiaoquan

2018-04-17

We provide here, for the first time, a new interfacial electron-induced electrochemiluminescence (IEIECL) system, realizing bionic construction of bioluminescence (BL) by exploiting electrochemiluminescence (ECL) and ITIES (the interface between two immiscible electrolyte solutions). Significantly, the superiority of the IEIECL system is embodied with the solution of the two bottlenecks encountered in the conventional ECL innovation: that are (a) the applications of hydrophobic luminophores in more commonly used aqueous solution are inhibited tremendously due to the poor inherent solubility and the instability of radicals and (b) the analytes, insoluble in water, are hard to be discovered in an aqueous system because of too little content. More productive IEIECL radiation, analogous to BL, originates from the triplet excited state porphyrin in comparison to the homogeneous ECL. The mechanism of IEIECL, as well as the interaction mechanism between IEIECL and charge transfer (comprising electron transfer (ET), ion transfer (IT), and facilitated ion transfer (FIT)) at the ITIES, are explored in detail. Finally, we emphasize the actual application potential of the IEIECL system with the detection of cytochrome c (Cyt c); it is a key biomolecule in the electron transport chain in the process of biological oxidation and is also an intermediate species in apoptosis. Potentially, the IEIECL system permits ones to explore the lifetime and diffusion path of free radicals, as well as imparting a possibility for the construction of a bionic sensor.

X-ray emission as a diagnostic from pseudospark-sourced electron beams

Energy Technology Data Exchange (ETDEWEB)

Bowes, D., E-mail: david.bowes@strath.ac.uk [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Yin, H.; He, W.; Zhang, L.; Cross, A.W.; Ronald, K.; Phelps, A.D.R. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Chen, D.; Zhang, P. [Computed Tomography Lab, School of Mathematical Sciences, Capital Normal University, Beijing 100048 (China); Chen, X.; Li, D. [Department of Electronic Engineering, Queen Mary University of London, London E1 4NS (United Kingdom)

2014-09-15

X-ray emission has been achieved using an electron beam generated by a pseudospark low-pressure discharge and utilised as a diagnostic for beam detection. A 300 A, 34 kV PS-sourced electron beam pulse of 3 mm diameter impacting on a 0.1 mm-thick molybdenum target generated X-rays which were detected via the use of a small, portable X-ray detector. Clear X-ray images of a micro-sized object were captured using an X-ray photodetector. This demonstrates the inducement of proton induced X-ray emission (PIXE) not only as an indicator of beam presence but also as a future X-ray source for small-spot X-ray imaging of materials.

Sequence dependence of electron-induced DNA strand breakage revealed by DNA nanoarrays

DEFF Research Database (Denmark)

Keller, Adrian; Rackwitz, Jenny; Cauët, Emilie

2014-01-01

The electronic structure of DNA is determined by its nucleotide sequence, which is for instance exploited in molecular electronics. Here we demonstrate that also the DNA strand breakage induced by low-energy electrons (18 eV) depends on the nucleotide sequence. To determine the absolute cross sec...

Silicon radiation detector analysis using back electron beam induced current

International Nuclear Information System (INIS)

Guye, R.

1987-01-01

A new technique for the observation and analysis of defects in silicon radiation detectors is described. This method uses an electron beam from a scanning electron microscope (SEM) impinging on the rear side of the p + n junction of the silicon detector, which itself is active and detects the electron beam induced current (EBIC). It is shown that this current is a sensitive probe of localized trapping centers, either at the junction surface or somewhere in the volume of the silicon crystal. (orig.)

Q-Dependence of the double capture cross sections measured by electron spectroscopy at 10 qkeV (q = 4-8). Comparison with other experimental data

Energy Technology Data Exchange (ETDEWEB)

Bordenave-Montesquieu, A.; Boudjema, M.; Benoit-Cattin, P.; Gleizes, A.; Moretto-Capelle, P.

1989-01-01

The q dependence of cross sections for double capture into autoionising states has been investigated by electron spectroscopy. It is shown that they are independent of the ionic core. Our results are compared with all other available experimental data obtained at 10 qkeV collision energy.

Q-Dependence of the double capture cross sections measured by electron spectroscopy at 10 qkeV (q = 4-8). Comparison with other experimental data

International Nuclear Information System (INIS)

Bordenave-Montesquieu, A.; Boudjema, M.; Benoit-Cattin, P.; Gleizes, A.; Moretto-Capelle, P.

1989-01-01

The q dependence of cross sections for double capture into autoionising states has been investigated by electron spectroscopy. It is shown that they are independent of the ionic core. Our results are compared with all other available experimental data obtained at 10 qkeV collision energy

Photo-Induced Electron Spin Polarization in a Narrow Band Gap Semiconductor Nanostructure

International Nuclear Information System (INIS)

Peter, A. John; Lee, Chang Woo

2012-01-01

Photo-induced spin dependent electron transmission through a narrow gap InSb/InGa x Sb 1−x semiconductor symmetric well is theoretically studied using transfer matrix formulism. The transparency of electron transmission is calculated as a function of electron energy for different concentrations of gallium. Enhanced spin-polarized photon assisted resonant tunnelling in the heterostructure due to Dresselhaus and Rashba spin-orbit coupling induced splitting of the resonant level and compressed spin-polarization are observed. Our results show that Dresselhaus spin-orbit coupling is dominant for the photon effect and the computed polarization efficiency increases with the photon effect and the gallium concentration

Ultrahigh resolution focused electron beam induced processing: the effect of substrate thickness

DEFF Research Database (Denmark)

van Dorp, Willem F; Lazic, Ivan; Beyer, André

2011-01-01

It is often suggested that the growth in focused electron beam induced processing (FEBIP) is caused not only by primary electrons, but also (and even predominantly) by secondary electrons (SEs). If that is true, the growth rate for FEBIP can be changed by modifying the SE yield. Results from our ...

Chemical changes induced on a TiO2 surface by electron bombardment

International Nuclear Information System (INIS)

Vergara, L.I.; Passeggi, M.C.G.; Ferron, J.

2007-01-01

We study the TiO 2 (Ti 4+ ) chemical reduction induced by electron bombardment using Auger electron spectroscopy and factor analysis. We show that the electron irradiation of a TiO 2 sample is characterized by the appearance of a lower Ti oxidation state, Ti 2 O 3 (Ti 3+ ), followed by a further deposition of carbon, which is present inevitably in the environment even under ultra-high vacuum conditions. The appearance of C over the surface is found to be a complex mechanism which affects the reduction process through passivation of the electron-induced oxygen desorption and formation of titanium carbide. For very high irradiation doses, we also found that the chemical changes on the surface are stopped due to the deposition of carbon in a graphitic form

Electron-electron scattering-induced channel hot electron injection in nanoscale n-channel metal-oxide-semiconductor field-effect-transistors with high-k/metal gate stacks

International Nuclear Information System (INIS)

Tsai, Jyun-Yu; Liu, Kuan-Ju; Lu, Ying-Hsin; Liu, Xi-Wen; Chang, Ting-Chang; Chen, Ching-En; Ho, Szu-Han; Tseng, Tseung-Yuen; Cheng, Osbert; Huang, Cheng-Tung; Lu, Ching-Sen

2014-01-01

This work investigates electron-electron scattering (EES)-induced channel hot electron (CHE) injection in nanoscale n-channel metal-oxide-semiconductor field-effect-transistors (n-MOSFETs) with high-k/metal gate stacks. Many groups have proposed new models (i.e., single-particle and multiple-particle process) to well explain the hot carrier degradation in nanoscale devices and all mechanisms focused on Si-H bond dissociation at the Si/SiO 2 interface. However, for high-k dielectric devices, experiment results show that the channel hot carrier trapping in the pre-existing high-k bulk defects is the main degradation mechanism. Therefore, we propose a model of EES-induced CHE injection to illustrate the trapping-dominant mechanism in nanoscale n-MOSFETs with high-k/metal gate stacks.

Experiences in running a complex electronic data capture system using mobile phones in a large-scale population trial in southern Nepal

OpenAIRE

Style, S.; Beard, B. J.; Harris-Fry, H.; Sengupta, A.; Jha, S.; Shrestha, B. P.; Rai, A.; Paudel, V.; Thondoo, M.; Pulkki-Brannstrom, A-M; Skordis-Worrall, J.; Manandhar, D. S.; Costello, A.; Saville, N. M.

2017-01-01

The increasing availability and capabilities of mobile phones make them a feasible means of data collection. Electronic Data Capture (EDC) systems have been used widely for public health monitoring and surveillance activities, but documentation of their use in complicated research studies requiring multiple systems is limited. This paper shares our experiences of designing and implementing a complex multi-component EDC system for a community-based four-armed cluster-Randomised Controlled Tria...

Experiences in running a complex electronic data capture system using mobile phones in a large-scale population trial in southern Nepal

OpenAIRE

Style, Sarah; Beard, B. James; Harris-Fry, Helen; Sengupta, Aman; Jha, Sonali; Shrestha, Bhim P.; Rai, Anjana; Paudel, Vikas; Thondoo, Meelan; Pulkki-Brannstrom, Anni-Maria; Skordis-Worrall, Jolene; Manandhar, Dharma S.; Costello, Anthony; Saville, Naomi M.

2017-01-01

ABSTRACT The increasing availability and capabilities of mobile phones make them a feasible means of data collection. Electronic Data Capture (EDC) systems have been used widely for public health monitoring and surveillance activities, but documentation of their use in complicated research studies requiring multiple systems is limited. This paper shares our experiences of designing and implementing a complex multi-component EDC system for a community-based four-armed cluster-Randomised Contro...

The future of focused electron beam-induced processing

International Nuclear Information System (INIS)

Hagen, C.W.

2014-01-01

A perspective is sketched for the field of focused electron beam-induced processing (FEBIP). The FEBIP lithography technique is compared to the very successful resist-based electron beam lithography (EBL) technique. The advantages of FEBIP over EBL are identified, the main advantage being its high spatial resolution. This will enable FEBIP to become an important lithography technique for the fabrication of devices with critical dimension in the range between 1 and 20 nm and serve as a complementary technique to EBL. It will be discussed what needs to be done to achieve this and what the potential applications are. (orig.)

Weak-beam electron microscopy of radiation-induced segregation

International Nuclear Information System (INIS)

Saka, H.

1983-01-01

The segregation of solute atoms to dislocations during irradiation by 1 MeV electrons in a HVEM was studied by measuring the dissociation width of extended dislocations in Cu-5.1 at.%Si, Cu-5.3 at.%Ge, Ag-9.4 at.% In and Ag-9.6 at.%Al alloys. 'Weak-beam' electron microscopy was used. In Cu-Si (oversized solute), Cu-Ge (oversize) and Ag-Al (undersize), solute enrichment was observed near dislocations, while in Ag-In (oversize) solute depletion was observed. The results are discussed in terms of current mechanisms for radiation-induced segregation. (author)

Double electron capture cross-sections of the ground state in the collisions of He2+ and Li3+ with He

International Nuclear Information System (INIS)

Purkait, M.

2004-01-01

We investigate the problem of the double charge transfer cross-section of a helium atom by bare ions of helium and lithium at energies ranging from 60 to 200 keV/amu. The boundary corrected continuum intermediate state approximation (BCCIS) is used to calculate the capture cross-section in the ground state. The continuum state of each electron has been accounted for in the formalism. The present results are compared with existing theoretical and experimental results. (authors)

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

CERN Multimedia

2002-01-01

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

Advanced ion beam analysis of materials using ion-induced fast electron

Energy Technology Data Exchange (ETDEWEB)

Kudo, Hiroshi; Tanabe, Atsushi; Ishihara, Toyoyuki [Tsukuba Univ., Ibaraki (Japan); and others

1997-03-01

Recent progress in the study of high-energy shadowing effect using ion-induced electron spectroscopy is reported with emphasis on a possibility of determination of local electronic structure in solids, which has been a difficult problem to approach with other experimental techniques. We demonstrate real-space determination of covalent-bond electron distribution in Si crystal. The analysis technique may provide a new field of ion beam analysis of solids. (author)

Pressure-induced changes in the electronic structure of solids

International Nuclear Information System (INIS)

McMahan, A.K.

1985-07-01

A variety of high-pressure metalization and metal-semimetal transitions, crystallographic phase transitions, and equation of state and lattice vibrational anomalies are reviewed in terms of the concepts of electronic transition and pressure-induced loss of covalency. 46 refs., 10 figs

Ultrafast molecular imaging by laser-induced electron diffraction

International Nuclear Information System (INIS)

Peters, M.; Nguyen-Dang, T. T.; Cornaggia, C.; Saugout, S.; Charron, E.; Keller, A.; Atabek, O.

2011-01-01

We address the feasibility of imaging geometric and orbital structures of a polyatomic molecule on an attosecond time scale using the laser-induced electron diffraction (LIED) technique. We present numerical results for the highest molecular orbitals of the CO 2 molecule excited by a near-infrared few-cycle laser pulse. The molecular geometry (bond lengths) is determined within 3% of accuracy from a diffraction pattern which also reflects the nodal properties of the initial molecular orbital. Robustness of the structure determination is discussed with respect to vibrational and rotational motions with a complete interpretation of the laser-induced mechanisms.

Halogenated pesticide analysis in orange juice by gas chromatography with electron capture detector (GC-ECD) with "6"3Ni nuclide

International Nuclear Information System (INIS)

Manhani, Kelly C.; Amaral, Priscila O.; Bustillos, José O.V.; Mendes, Cristiana de A.; Lacerda, João P.A. de; Silva, Jorge L. da; Instituto de Pesquisas Tecnológicas do Estado de São Paulo

2017-01-01

Brazil has been gain space in the market of orange juice in the last years. For the exportation of this product to keep growing, its quality of this product must be ensured by putting in force more strict legislations and custom barriers, in order to improve the well-being and health of the population. In this work were analyzed four orange juices brands produced in the State of São Paulo. It was quantified the acaricide known as Dicofol (2,2,2-trichloro-1,1-bis(4-chlorophenyl) ethanol) widely used to combat the Citrusleprosis virus, transmitted by mites to the citrus culture. This pesticide was chosen due to its importance in the production of orange in large scale and their indiscriminate use may pose risks to humans and of environment. The analytical technique applied was gas chromatography coupled with electron capture detector (GC-ECD) using the "6"3Ni nuclide. This beta (β) radiation source ionizes the carrier gas (N_2), generating an electron current that forms the baseline. The analites pass through the detector and capture electrons, generating the analytical signal that is proportional to the concentration of analite. The sample preparation was done by QuEChERS. The limits of detection (LOD) and quantification (LOQ) found were 0.005 and 0.025 mg kg"-"1 respectively. The applied methodology was efficient and presented excellent analytical sensitivity for the pesticide Dicofol, being that of four samples analyzed, only in one was found concentration of 0.03 mg kg"-"1, above the LOQ, however below the Maximum Residue Limit (MRL) for fruits (0.1 mg kg"-"1) established by Codex alimentarius. (author)

Halogenated pesticide analysis in orange juice by gas chromatography with electron capture detector (GC-ECD) with {sup 63}Ni nuclide

Energy Technology Data Exchange (ETDEWEB)

Manhani, Kelly C.; Amaral, Priscila O.; Bustillos, José O.V.; Mendes, Cristiana de A.; Lacerda, João P.A. de; Silva, Jorge L. da, E-mail: ovega@ipen.br, E-mail: kmanhani@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (CQMA/IPEN-CNEN-SP), Sao Paulo, SP (Brazil). Centro de Química e Meio Ambiente; Instituto de Pesquisas Tecnológicas do Estado de São Paulo (LAQ- CQuim/IPT-SP), SP (Brazil). Lab. de Análises Químicas

2017-11-01

Brazil has been gain space in the market of orange juice in the last years. For the exportation of this product to keep growing, its quality of this product must be ensured by putting in force more strict legislations and custom barriers, in order to improve the well-being and health of the population. In this work were analyzed four orange juices brands produced in the State of São Paulo. It was quantified the acaricide known as Dicofol (2,2,2-trichloro-1,1-bis(4-chlorophenyl) ethanol) widely used to combat the Citrusleprosis virus, transmitted by mites to the citrus culture. This pesticide was chosen due to its importance in the production of orange in large scale and their indiscriminate use may pose risks to humans and of environment. The analytical technique applied was gas chromatography coupled with electron capture detector (GC-ECD) using the {sup 63}Ni nuclide. This beta (β) radiation source ionizes the carrier gas (N{sub 2}), generating an electron current that forms the baseline. The analites pass through the detector and capture electrons, generating the analytical signal that is proportional to the concentration of analite. The sample preparation was done by QuEChERS. The limits of detection (LOD) and quantification (LOQ) found were 0.005 and 0.025 mg kg{sup -1} respectively. The applied methodology was efficient and presented excellent analytical sensitivity for the pesticide Dicofol, being that of four samples analyzed, only in one was found concentration of 0.03 mg kg{sup -1}, above the LOQ, however below the Maximum Residue Limit (MRL) for fruits (0.1 mg kg{sup -1}) established by Codex alimentarius. (author)

CHAOTIC CAPTURE OF NEPTUNE TROJANS

International Nuclear Information System (INIS)

Nesvorny, David; Vokrouhlicky, David

2009-01-01

Neptune Trojans (NTs) are swarms of outer solar system objects that lead/trail planet Neptune during its revolutions around the Sun. Observations indicate that NTs form a thick cloud of objects with a population perhaps ∼10 times more numerous than that of Jupiter Trojans and orbital inclinations reaching ∼25 deg. The high inclinations of NTs are indicative of capture instead of in situ formation. Here we study a model in which NTs were captured by Neptune during planetary migration when secondary resonances associated with the mean-motion commensurabilities between Uranus and Neptune swept over Neptune's Lagrangian points. This process, known as chaotic capture, is similar to that previously proposed to explain the origin of Jupiter's Trojans. We show that chaotic capture of planetesimals from an ∼35 Earth-mass planetesimal disk can produce a population of NTs that is at least comparable in number to that inferred from current observations. The large orbital inclinations of NTs are a natural outcome of chaotic capture. To obtain the ∼4:1 ratio between high- and low-inclination populations suggested by observations, planetary migration into a dynamically excited planetesimal disk may be required. The required stirring could have been induced by Pluto-sized and larger objects that have formed in the disk.

Radiation damage in uranium under electron irradiation of energies up to 20 MeV

International Nuclear Information System (INIS)

Emets, N.L.; Zelenskij, V.F.; Kuz'menko, V.A.; Ranyuk, Yu.N.; Reznichenko, Eh.A.; Shilyaev, B.A.; Yamnitskij, V.A.

1980-01-01

The problem of conservation of primary radiation-induced defects in uranium irradiated by electrons with the energy exceeding photo fission threshold is considered. Calculation of uranium burnout is carried out. Calculations are conducted by the method of mathematical simulation, using some nuclear models; development of electromagnetic cascade in uranium, photofission process, elastic and inelastic electron scattering, as well as some secondary processes are taken into account. Proved is the fact of anomalous growth of uranium under electron irradiation, registered earlier experimentally. It is shown, that in case of acquiring the value Ed=15 eV radiation uranium growth at low levels of burnout can be explained by the complete capture of all the primary radiationn-induced defects into dislocation loops [ru

AMUC: Associated Motion capture User Categories.

Science.gov (United States)

Norman, Sally Jane; Lawson, Sian E M; Olivier, Patrick; Watson, Paul; Chan, Anita M-A; Dade-Robertson, Martyn; Dunphy, Paul; Green, Dave; Hiden, Hugo; Hook, Jonathan; Jackson, Daniel G

2009-07-13

The AMUC (Associated Motion capture User Categories) project consisted of building a prototype sketch retrieval client for exploring motion capture archives. High-dimensional datasets reflect the dynamic process of motion capture and comprise high-rate sampled data of a performer's joint angles; in response to multiple query criteria, these data can potentially yield different kinds of information. The AMUC prototype harnesses graphic input via an electronic tablet as a query mechanism, time and position signals obtained from the sketch being mapped to the properties of data streams stored in the motion capture repository. As well as proposing a pragmatic solution for exploring motion capture datasets, the project demonstrates the conceptual value of iterative prototyping in innovative interdisciplinary design. The AMUC team was composed of live performance practitioners and theorists conversant with a variety of movement techniques, bioengineers who recorded and processed motion data for integration into the retrieval tool, and computer scientists who designed and implemented the retrieval system and server architecture, scoped for Grid-based applications. Creative input on information system design and navigation, and digital image processing, underpinned implementation of the prototype, which has undergone preliminary trials with diverse users, allowing identification of rich potential development areas.

Rapid differentiation of rocky mountain spotted fever from chickenpox, measles, and enterovirus infections and bacterial meningitis by frequency-pulsed electron capture gas-liquid chromatographic analysis of sera.

Science.gov (United States)

Brooks, J B; McDade, J E; Alley, C C

1981-01-01

Normal sera and sera from patients with Rocky Mountain spotted fever, chickenpox, enterovirus infections, measles, and Neisseria meningitidis infections were extracted with organic solvents under acidic and basic conditions and then derivatized with trichloroethanol or heptafluorobutyric anhydride-ethanol to form electron-capturing derivatives of organic acids, alcohols, and amines. The derivatives were analyzed by frequency-pulsed electron capture gas-liquid chromatography (FPEC-GLC). There were unique differences in the FPEC-GLC profiles of sera obtained from patients with these respective diseases. With Rocky Mountain spotted fever patients, typical profiles were detected as early as 1 day after onset of disease and before antibody could be detected in the serum. Rapid diagnosis of Rocky Mountain spotted fever by FPEC-GLC could permit early and effective therapy, thus preventing many deaths from this disease. PMID:7276147

Neutron Capture Gamma-Ray Spectroscopy. Proceedings of the International Symposium on Neutron Capture Gamma-Ray Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

NONE

1969-11-15

Experimental capabilities in the field of neutron capture gamma-ray spectroscopy have expanded greatly in the last few years; this has been due in large part to the advent of high-quality Ge(Li) detectors, improvements in electronic data processing, and improvements in bent-crystal spectrometers. Previously unsuspected phenomena, such as the '5. 5-MeV1 anomaly, have appeared and new research tools, such as neutron guide tubes, have been brought into use. Equally exciting developments have occurred in the theory of neutron capture. Complex spectra have yielded to analysis after account had been taken of such effects as vibration, rotation and Coriolis forces, and the theoretical prediction of capture spectra seems to be a future possibility. In view of the International Atomic Energy Agency's close interest in this subject and the need for an international exchange of ideas to analyse and study the latest developments, the organizers of the Symposium felt that work on neutron capture gamma-ray spectroscopy had achieved such valuable and significant results that the time had come for this information to be presented, examined and discussed internationally.

Neutron Capture Gamma-Ray Spectroscopy. Proceedings of the International Symposium on Neutron Capture Gamma-Ray Spectroscopy

International Nuclear Information System (INIS)

1969-01-01

Experimental capabilities in the field of neutron capture gamma-ray spectroscopy have expanded greatly in the last few years; this has been due in large part to the advent of high-quality Ge(Li) detectors, improvements in electronic data processing, and improvements in bent-crystal spectrometers. Previously unsuspected phenomena, such as the '5. 5-MeV1 anomaly, have appeared and new research tools, such as neutron guide tubes, have been brought into use. Equally exciting developments have occurred in the theory of neutron capture. Complex spectra have yielded to analysis after account had been taken of such effects as vibration, rotation and Coriolis forces, and the theoretical prediction of capture spectra seems to be a future possibility. In view of the International Atomic Energy Agency's close interest in this subject and the need for an international exchange of ideas to analyse and study the latest developments, the organizers of the Symposium felt that work on neutron capture gamma-ray spectroscopy had achieved such valuable and significant results that the time had come for this information to be presented, examined and discussed internationally

The impact of irradiation induced specimen charging on microanalysis in a scanning electron microscope

International Nuclear Information System (INIS)

Stevens-Kalceff, M.A.

2003-01-01

Full text: It is necessary to assess and characterize the perturbing influences of experimental probes on the specimens under investigation. The significant influence of electron beam irradiation on poorly conducting materials has been assessed by a combination of specialized analytical scanning electron and scanning probe microscopy techniques including Cathodoluminescence Microanalysis and Kelvin Probe Microscopy. These techniques enable the defect structure and the residual charging of materials to be characterized at high spatial resolution. Cathodoluminescence is the non-incandescent emission of light resulting from the electron irradiation. CL microscopy and spectroscopy in a Scanning Electron Microscope (SEM) enables high spatial resolution and high sensitivity detection of defects in poorly conducting materials. Local variations in the distribution of defects can be non-destructively characterized with high spatial (lateral and depth) resolution by adjusting electron beam parameters to select the specimen micro-volume of interest. Kelvin Probe Microscopy (KPM) is a Scanning Probe Microscopy technique in which long-range Coulomb forces between a conductive atomic force probe and the specimen enable the surface potential to be characterized with high spatial resolution. A combination of Kelvin Probe Microscopy (KPM) and Cathodoluminescence (CL) microanalysis has been used to characterize ultra pure silicon dioxide exposed to electron irradiation in a Scanning Electron Microscope. Silicon dioxide is an excellent model specimen with which to investigate charging induced effects. It is a very poor electrical conductor, homogeneous and electron irradiation produces easily identifiable surface modification which enables irradiated regions to be easily and unambiguously located. A conductive grounded coating is typically applied to poorly conducting specimens prior to investigation in an SEM to prevent deflection of the electron beam and surface charging, however

Electron-photon and electron-electron interactions in the presence of strong electromagnetic fields

International Nuclear Information System (INIS)

Surzhykov, A.; Fritzsche, S.; Stoehlker, Th.

2010-01-01

During the last decade, photon emission from highly-charged, heavy ions has been in the focus of intense studies at the GSI accelerator and storage ring facility in Darmstadt. These studies have revealed unique information about the electron-electron and electron-photon interactions in the presence of extremely strong nuclear fields. Apart from the radiative electron capture processes, characteristic photon emission following collisional excitation of projectile ions has also attracted much interest. In this contribution, we summarize the recent theoretical studies on the production of excited ionic states and their subsequent radiative decay. We will pay special attention to the angular and polarization properties of Kα emission from helium-like ions produced by means of dielectronic recombination. The results obtained for this (resonant) capture process will be compared with the theoretical predictions for the characteristic X-rays following Coulomb excitation and radiative recombination of few-electron, heavy ions. Work is supported by Helmholtz Association and GSl under the project VH-NG--421. (author)

Dynamics of the spatial electron density distribution of EUV-induced plasmas

Science.gov (United States)

van der Horst, R. M.; Beckers, J.; Osorio, E. A.; Banine, V. Y.

2015-11-01

We studied the temporal evolution of the electron density distribution in a low pressure pulsed plasma induced by high energy extreme ultraviolet (EUV) photons using microwave cavity resonance spectroscopy (MCRS). In principle, MCRS only provides space averaged information about the electron density. However, we demonstrate here the possibility to obtain spatial information by combining multiple resonant modes. It is shown that EUV-induced plasmas, albeit being a rather exotic plasma, can be explained by known plasma physical laws and processes. Two stages of plasma behaviour are observed: first the electron density distribution contracts, after which it expands. It is shown that the contraction is due to cooling of the electrons. The moment when the density distribution starts to expand is related to the inertia of the ions. After tens of microseconds, the electrons reached the wall of the cavity. The speed of this expansion is dependent on the gas pressure and can be divided into two regimes. It is shown that the acoustic dominated regime the expansion speed is independent of the gas pressure and that in the diffusion dominated regime the expansion depends reciprocal on the gas pressure.

Dynamics of the spatial electron density distribution of EUV-induced plasmas

International Nuclear Information System (INIS)

Van der Horst, R M; Beckers, J; Banine, V Y; Osorio, E A

2015-01-01

We studied the temporal evolution of the electron density distribution in a low pressure pulsed plasma induced by high energy extreme ultraviolet (EUV) photons using microwave cavity resonance spectroscopy (MCRS). In principle, MCRS only provides space averaged information about the electron density. However, we demonstrate here the possibility to obtain spatial information by combining multiple resonant modes. It is shown that EUV-induced plasmas, albeit being a rather exotic plasma, can be explained by known plasma physical laws and processes. Two stages of plasma behaviour are observed: first the electron density distribution contracts, after which it expands. It is shown that the contraction is due to cooling of the electrons. The moment when the density distribution starts to expand is related to the inertia of the ions. After tens of microseconds, the electrons reached the wall of the cavity. The speed of this expansion is dependent on the gas pressure and can be divided into two regimes. It is shown that the acoustic dominated regime the expansion speed is independent of the gas pressure and that in the diffusion dominated regime the expansion depends reciprocal on the gas pressure. (fast track communication)

Detection efficiency for radionuclides decaying by electron capture and gamma-Ray; Calculo de la eficiencia de deteccion de nucleidos que se desintegran por captura elec- tronica y emision gamma

Energy Technology Data Exchange (ETDEWEB)

Grau, A; Fernandez, A

1985-07-01

In this paper, the electron capture partial counting efficiency vs the figure of merit for electron-capture and gamma-ray emitters has been computed. The radionuclides tabulated are 48{sup c}r, 54{sup M}n, 57{sup C}o 56{sup N}i, 72{sup S}e, 73{sup A}s, 85{sup S}r, 88{sup Z}r, 92{sup N}b, 103{sup P}d, 111{sup l}n, 119{sup S}b, 125{sup I}, 139{sup C}e and 152{sup D}y. It has been assumed that the liquid is a toluene based scintillator solution in standard glass vials containing 15 cm{sup 3}. (Author) 17 refs.

pH-responsive deoxyribonucleic acid capture/release by polydopamine functionalized magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wang, Yu; Ma, Xiangdong; Ding, Chun; Jia, Li, E-mail: jiali@scnu.edu.cn

2015-03-03

Highlights: • PDA@Fe{sub 3}O{sub 4} were prepared and applied for efficient extraction of DNA from pathogens. • The DNA capture and release by PDA@Fe{sub 3}O{sub 4} was pH-induced. • The adsorption capacity of PDA@Fe{sub 3}O{sub 4} for DNA was 161 mg g{sup −1}. • PDA@Fe{sub 3}O{sub 4} based MSPE was combined with PCR and CE for rapid detection of pathogens. - Abstract: Polydopamine functionalized magnetic nanoparticles (PDA@Fe{sub 3}O{sub 4}) were prepared and characterized by transmission electron microscopy, scanning electron microscopy, zeta potential and vibrating sample magnetometry. They were found to enable highly efficient capture of genomic deoxyribonucleic acid (DNA). The adsorption capacity of PDA@Fe{sub 3}O{sub 4} for genomic DNA can reach 161 mg g{sup −1}. The extraction protocol used aqueous solutions for DNA binding to and releasing from the surface of the magnetic particles based on the pH inducing the charge switch of amino and phenolic hydroxyl groups on PDA@Fe{sub 3}O{sub 4}. The extracted DNA with high quality (A{sub 260}/A{sub 280} = 1.80) can be directly used as templates for polymerase chain reaction (PCR) followed by capillary electrophoresis (CE) analysis. None of the toxic chemical reagents and PCR inhibitors was used throughout the whole procedure. PDA@Fe{sub 3}O{sub 4} based magnetic solid phase extraction (MSPE) method was superior to those using commercial kit and traditional phenol–chloroform extraction methods in yield of DNA. The developed PDA@Fe{sub 3}O{sub 4} based MSPE-PCR-CE method was applied for simultaneous and fast detection of Listeria monocytogenes and Escherichia coli O157:H7 in milk.

Shifting of the electron-capture-to-the-continuum peak in proton-helium collisions at 10 and 20 keV

International Nuclear Information System (INIS)

Bhattacharya, S.; Deb, N.C.; Roy, K.; Sahoo, S.; Crothers, D.S.F.

2005-01-01

A refined theoretical approach has been developed to study the double-differential cross sections (DDCS's) in proton-helium collisions as a function of the ratio of ionized electron velocity to the incident proton velocity. The refinement is done in the present coupled-channel calculation by introducing a continuum distorted wave in the final state coupled with discrete states including direct as well as charge transfer channels. It is confirmed that the electron-capture-to-the-continuum (ECC) peak is slightly shifted to a lower electron velocity than the equivelocity position. Comparing measurements and classical trajectory Monte Carlo (CTMC) calculations at 10 and 20 keV proton energies, excellent agreement of the ECC peak heights is achieved at both energies. However, a minor disagreement in the peak positions between the present calculation and the CTMC results is noted. A smooth behavior of the DDCS is found in the present calculation on both sides of the peak whereas the CTMC results show some oscillatory behavior particularly to the left of the peak, associated with the statistical nature of CTMC calculations

Positron annihilation and pressure-induced electronic s-d transition

International Nuclear Information System (INIS)

McMahan, A.K.; Skriver, H.L.

1985-06-01

The polycrystalline, partial annihilation rates for positrons in compressed cesium have been calculated using the linear muffin-tin orbitals method. These results suggest that the pressure-induced electronic s-d transition in Cs should be directly observable by momentum sensitive positron annihilation experiments

Hot-electrons-induced ultrafast demagnitization in Co/Pt multilayers

NARCIS (Netherlands)

Bergeard, N.; Hehn, M.; Mangin, S.; Lengaigne, G.; Montaigne, F.; Lalieu, M. L. M.; Koopmans, B.; Malinowski, G.

2016-01-01

Using specially engineered structures to tailor the optical absorption in a metallic multilayer, we analyze the magnetization dynamics of a Co/Pt multilayer buried below a thick Cu layer. We demonstrate that hot electrons alone can very efficiently induce ultrafast demagnetization. Simulations based

Inelastic electron scattering and radiative pion capture to the lowest 1+ and 2+ isovector levels in A=12 nuclei. Continuity-equation effects

International Nuclear Information System (INIS)

Eramzhyan, R.A.; Gmitro, M.; Kaipov, T.D.; Kamalov, S.S.; Mach, R.

1983-01-01

Continuity equation for the nuclear electric charge and convection current has been used in an analysis of nuclear transition densities in 12 C. The results differ considerably from the former derivations. Standard M1 and calculated E2 nuclear transition densities are fixed which provide an accurate description of the electron scattering data. Such a nuclear structure imput is used in the radiative pion capture calculations

Probabilities and energies to obtain the counting efficiency of electron-capture nuclides. KLMN model; Probabilidades y energias de reestructuracion atomica subsiguientes a la captura electronica. Modelo KLMN

Energy Technology Data Exchange (ETDEWEB)

Galiano, G.; Grau, A.

1994-07-01

An intelligent computer program has been developed to obtain the mathematical formulae to compute the probabilities and reduced energies of the different atomic rearrangement pathways following electron-capture decay. Creation and annihilation operators for Auger and X processes have been introduced. Taking into account the symmetries associated with each process, 262 different pathways were obtained. This model allows us to obtain the influence of the M-electro capture in the counting efficiency when the atomic number of the nuclide is high. (Author)

Determination of Psub(K) values to the 172, 103 and 97 keV levels and the fluorescence yield. omega. sub(K) of Eu after electron capture by /sup 153/Gd

Energy Technology Data Exchange (ETDEWEB)

Singh, K; Grewal, B S; Sahota, H S [Punjabi Univ., Patiala (India). Dept. of Physics

1985-03-01

From an analysis of K x-ray-..gamma..-ray sum peaks observed with an intrinsic Ge detector the K-capture probabilities (Psub(K)) to the 172, 103 and 97 keV levels in the decay of /sup 153/Gd have been determined; these yield an electron-capture energy Qsub(EC)=245 +- 2. The K-capture probability to the 172 keV level differs significantly from that found in the literature. With these results the K-shell fluorescence yield of Eu is ..omega..sub(K)=0.935 +- 0.019.

Cross sections of electron loss and capture for beams of O{sup +} in water vapor from the energy range of 0,2 to 1,2 MeV; Secoes de choque de perda e captura eletronica para feixes de O{sup +} em vapor de agua em uma faixa de energia entre 0,2 e 1,2 MeV

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Vitor Jesus de

2015-06-01

The study of the interactions between atoms and molecules is important for the knowledge of the cross sections of the processes that contribute to the deposition of energy by charged particle beams used in radiotherapy planning and transport particle simulation codes. Heavy ions, such as oxygen, induce many cellular and molecular damages in human cells.as a result of interaction between the projectile and atoms and molecules. The use of proton and carbon as the projectile interacting with water molecules is well characterized, however there are few studies with oxygen ions. In this work we are interested in the study of electron loss (projectile ionization) and electron capture with charge state 1+. The Pelletron accelerator of 1.7 MeV from the Federal University of Rio de Janeiro housed in the Atomic and Molecular collisions Laboratory (LACAM) has been used, which can accelerate atomic and molecular ions up to speeds of the order of hundredths of light speed, and consists of the source of negative ions, the Wien filter, the accelerator itself and the magnet load selector. The detection device used to evaluate the processes of interaction (capture and loss) between the beam of the O{sup +} and the water molecule is a Microchannel Plate (MCP) at the position sensitive anode. The collisions of O{sup +} beans are being studied in the range of 0.2 to 1.2 MeV with water vapor (Z = 10). Were obtained the respective absolute cross sections for electron loss and electron capture and compared with the cross sections of the molecule methane (CH4 → Z = 10), the isoelectronic water molecule. The experimental results show an agreement between the measurements with water and methane. Comparisons were made with results of theoretical models for electron loss using the 'Free Collision Model' and for capture the Bohr and Lindhard model. The theoretical results for electron loss show an agreement of experimental data with the model used. The model of Bohr and Lindhard

ELECTRON-CAPTURE IN HIGHLY-CHARGED ION-ATOM COLLISIONS

NARCIS (Netherlands)

MORGENSTERN, R

1993-01-01

An attempt is made to identify the most important mechanisms responsible for the rearrangement of electrons during collisions between multiply charged ions and atoms at keV energies. It is discussed to which extent the influence of binding energy, angular momentum of heavy particles and electrons,

Electron-beam-irradiation-induced crystallization of amorphous solid phase change materials

Science.gov (United States)

Zhou, Dong; Wu, Liangcai; Wen, Lin; Ma, Liya; Zhang, Xingyao; Li, Yudong; Guo, Qi; Song, Zhitang

2018-04-01

The electron-beam-irradiation-induced crystallization of phase change materials in a nano sized area was studied by in situ transmission electron microscopy and selected area electron diffraction. Amorphous phase change materials changed to a polycrystalline state after being irradiated with a 200 kV electron beam for a long time. The results indicate that the crystallization temperature strongly depends on the difference in the heteronuclear bond enthalpy of the phase change materials. The selected area electron diffraction patterns reveal that Ge2Sb2Te5 is a nucleation-dominated material, when Si2Sb2Te3 and Ti0.5Sb2Te3 are growth-dominated materials.

Chemical processes in neutron capture therapy

International Nuclear Information System (INIS)

Brown, B.J.

1975-01-01

Research into the radiation chemical effects of neutron capture therapy are described. In the use of neutron capture therapy for the treatment of brain tumours, compounds containing an activatable nuclide are selectively concentrated within tumour tissue and irradiated with neutrons. Target compounds for use in therapy must accumulate selectively in high concentrations in the tumour and must be non toxic to the patient. The most suitable of these are the boron hydrides. Radiation dosages, resulting from neutron capture in normal tissue constituents are tabulated. As part of the program to study the radiation-induced chemical processes undergone by boron target compounds, the radiolytic degredation of boron hydride and phenyl boric acid system was investigated. No direct dependence between the yield of the transient radiolytic species and the concentration of the B-compound was observed. (author)

A New Mass Criterium for Electron Capture Supernovae

Science.gov (United States)

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

Micromotors to capture and destroy anthrax simulant spores.

Science.gov (United States)

Orozco, Jahir; Pan, Guoqing; Sattayasamitsathit, Sirilak; Galarnyk, Michael; Wang, Joseph

2015-03-07

Towards addressing the need for detecting and eliminating biothreats, we describe a micromotor-based approach for screening, capturing, isolating and destroying anthrax simulant spores in a simple and rapid manner with minimal sample processing. The B. globilli antibody-functionalized micromotors can recognize, capture and transport B. globigii spores in environmental matrices, while showing non-interactions with excess of non-target bacteria. Efficient destruction of the anthrax simulant spores is demonstrated via the micromotor-induced mixing of a mild oxidizing solution. The new micromotor-based approach paves a way to dynamic multifunctional systems that rapidly recognize, isolate, capture and destroy biological threats.

Application of positron annihilation induced auger electron spectroscopy to the study of surface chemistry

International Nuclear Information System (INIS)

Weiss, A.H.; Yang, G.; Nangia, A.; Kim, J.H.; Fazleev, N.G.

1996-01-01

Positron annihilation induced Auger Electron Spectroscopy (PAES), makes use a beam of low energy positrons to excite Auger transitions by annihilating core electrons. This novel mechanism provides PAES with a number of unique features which distinguishes it from other methods of surface analysis. In PAES the very large collisionally induced secondary electron background which is present under the low energy Auger peaks using conventional techniques can be eliminated by using a positron beam whose energy is below the range of Auger electron energies. In addition, PAES is more surface selective than conventional Auger Spectroscopy because the PAES signal originates almost exclusively from the topmost atomic layer due to the fact that the positrons annihilating with the core electrons are trapped in an image correlation well just outside the surface. In this paper, recent applications of Positron Annihilation Induced Auger Electron Spectroscopy (PAES) to the study of surface structure and surface chemistry will be discussed including studies of the growth, alloying and inter-diffusion of ultrathin layers of metals, metals on semiconductors, and semiconductors on semiconductors. In addition, the possibilities for future application of PAES to the study of catalysis and surface chemistry will be outlined. (author)

New measurement of neutron capture resonances of 209Bi

CERN Document Server

Domingo-Pardo, C.; Aerts, G.; Alvarez-Pol, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Becvar, F.; Berthoumieux, E.; Calvino, F.; Cano-Ott, D.; Capote, R.; Carrillode Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillman, I.; Dolfini, R.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fujii, K.; Furman, W.; Gallino, R.; Goncalves, I.; Gonzalez-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Isaev, S.; Jericha, E.; Kadi, Y.; Kappeler, F.; Karamanis, D.; Karadimos, D.; Kerveno, M.; Ketlerov, V.; Koehler, P.; Konovalov, V.; Kossionides, E.; Krticka, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Mastinu, P.; Mengoni, A.; Milazzo, P.M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; Oshima, M.; O'Brien, S.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J.L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, Alberto; Villamarin, D.; Vincente, M.C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wendler, H.; Wiescher, M.; Wisshak, K.

2006-01-01

The neutron capture cross section of Bi209 has been measured at the CERN n TOF facility by employing the pulse-height-weighting technique. Improvements over previous measurements are mainly because of an optimized detection system, which led to a practically negligible neutron sensitivity. Additional experimental sources of systematic error, such as the electronic threshold in the detectors, summing of gamma-rays, internal electron conversion, and the isomeric state in bismuth, have been taken into account. Gamma-ray absorption effects inside the sample have been corrected by employing a nonpolynomial weighting function. Because Bi209 is the last stable isotope in the reaction path of the stellar s-process, the Maxwellian averaged capture cross section is important for the recycling of the reaction flow by alpha-decays. In the relevant stellar range of thermal energies between kT=5 and 8 keV our new capture rate is about 16% higher than the presently accepted value used for nucleosynthesis calculations. At th...

The feasibility of using 'bring your own device' (BYOD) technology for electronic data capture in multicentre medical audit and research.

Science.gov (United States)

Faulds, M C; Bauchmuller, K; Miller, D; Rosser, J H; Shuker, K; Wrench, I; Wilson, P; Mills, G H

2016-01-01

Large-scale audit and research projects demand robust, efficient systems for accurate data collection, handling and analysis. We utilised a multiplatform 'bring your own device' (BYOD) electronic data collection app to capture observational audit data on theatre efficiency across seven hospital Trusts in South Yorkshire in June-August 2013. None of the participating hospitals had a dedicated information governance policy for bring your own device. Data were collected by 17 investigators for 392 individual theatre lists, capturing 14,148 individual data points, 12, 852 (91%) of which were transmitted to a central database on the day of collection without any loss of data. BYOD technology enabled accurate collection of a large volume of secure data across multiple NHS organisations over a short period of time. Bring your own device technology provides a method for collecting real-time audit, research and quality improvement data within healthcare systems without compromising patient data protection. © 2015 The Association of Anaesthetists of Great Britain and Ireland.

Cross sections for one-electron capture by highly stripped ions of Be, B and C from H2 and Ar below 10 keV

International Nuclear Information System (INIS)

Takagi, S.; Ohtani, S.; Kadota, K.; Fujita, J.

1982-03-01

Cross sections for one-electron capture by highly stripped ions of Be, B and C from H 2 and Ar are measured at low energies below 10 keV. The cross sections are nearly independent of the collision energy investigated. The distinct oscillation with incident ionic charge g in the cross sections are observed. (author)

Positron annihilation induced Auger electron spectroscopic studies of oxide surfaces

Science.gov (United States)

Nadesalingam, Manori

2005-03-01

Defects on oxide surfaces are well known to play a key role in catalysis. TiO2, MgO, SiO2 surfaces were investigated using Time-Of-Flight Positron induced Auger Electron Spectroscopy (TOF-PAES). Previous work in bulk materials has demonstrated that positrons are particularly sensitive to charged defects. In PAES energetic electron emission results from Auger transitions initiated by annihilation of core electrons with positrons trapped in an image-potential well at the surface. Annealed samples in O2 environment show a strong Auger peak of Oxygen. The implication of these results will be discussed

Resistance and sheet resistance measurements using electron beam induced current

International Nuclear Information System (INIS)

Czerwinski, A.; Pluska, M.; Ratajczak, J.; Szerling, A.; KaPtcki, J.

2006-01-01

A method for measurement of spatially uniform or nonuniform resistance in layers and strips, based on electron beam induced current (EBIC) technique, is described. High electron beam currents are used so that the overall resistance of the measurement circuit affects the EBIC signal. During the evaluation, the electron beam is scanned along the measured object, whose load resistance varies with the distance. The variation is compensated by an adjustable resistance within an external circuit. The method has been experimentally deployed for sheet resistance determination of buried regions of lateral confinements in semiconductor laser heterostructures manufactured by molecular beam epitaxy

Ultrafast Hot Electron Induced Phase Transitions in Vanadium Dioxide

Directory of Open Access Journals (Sweden)

Haglund R. F.

2013-03-01

Full Text Available The Au/Cr/VO2/Si system was investigated in pump–probe experiments. Hot-electrons generated in the Au were found to penetrate into the underlying VO2 and couple with its lattice inducing a semiconductor-to-metal phase transition in ~2 picoseconds.

Coherent Electron Scattering Captured by an Attosecond Quantum Stroboscope

International Nuclear Information System (INIS)

Mauritsson, J.; Johnsson, P.; Mansten, E.; Swoboda, M.; Ruchon, T.; L'Huillier, A.; Schafer, K. J.

2008-01-01

We demonstrate a quantum stroboscope based on a sequence of identical attosecond pulses that are used to release electrons into a strong infrared (IR) laser field exactly once per laser cycle. The resulting electron momentum distributions are recorded as a function of time delay between the IR laser and the attosecond pulse train using a velocity map imaging spectrometer. Because our train of attosecond pulses creates a train of identical electron wave packets, a single ionization event can be studied stroboscopically. This technique has enabled us to image the coherent electron scattering that takes place when the IR field is sufficiently strong to reverse the initial direction of the electron motion causing it to rescatter from its parent ion

Dynamical nuclear spin polarization induced by electronic current through double quantum dots

International Nuclear Information System (INIS)

Lopez-Monis, Carlos; Platero, Gloria; Inarrea, Jesus

2011-01-01

We analyse electron-spin relaxation in electronic transport through coherently coupled double quantum dots (DQDs) in the spin blockade regime. In particular, we focus on hyperfine (HF) interaction as the spin-relaxation mechanism. We pay special attention to the effect of the dynamical nuclear spin polarization induced by the electronic current on the nuclear environment. We discuss the behaviour of the electronic current and the induced nuclear spin polarization versus an external magnetic field for different HF coupling intensities and interdot tunnelling strengths. We take into account, for each magnetic field, all HF-mediated spin-relaxation processes coming from different opposite spin level approaches. We find that the current as a function of the external magnetic field shows a peak or a dip and that the transition from a current dip to a current peak behaviour is obtained by decreasing the HF coupling or by increasing the interdot tunnelling strength. We give a physical picture in terms of the interplay between the electrons tunnelling out of the DQD and the spin-flip processes due to the nuclear environment.

The role of low-energy electrons in focused electron beam induced deposition: four case studies of representative precursors

Directory of Open Access Journals (Sweden)

Rachel M. Thorman

2015-09-01

Full Text Available Focused electron beam induced deposition (FEBID is a single-step, direct-write nanofabrication technique capable of writing three-dimensional metal-containing nanoscale structures on surfaces using electron-induced reactions of organometallic precursors. Currently FEBID is, however, limited in resolution due to deposition outside the area of the primary electron beam and in metal purity due to incomplete precursor decomposition. Both limitations are likely in part caused by reactions of precursor molecules with low-energy (3, Pt(PF34, Co(CO3NO, and W(CO6. Through these case studies, it is evident that this combination of studies can provide valuable insight into potential mechanisms governing deposit formation in FEBID. Although further experiments and new approaches are needed, these studies are an important stepping-stone toward better understanding the fundamental physics behind the deposition process and establishing design criteria for optimized FEBID precursors.

Phase separation and d-wave superconductivity induced by extended electron-exciton interaction

Energy Technology Data Exchange (ETDEWEB)

Cheng Ming [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)], E-mail: cheng896@hotmail.com; Su Wupei [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)

2008-12-15

Using an auxiliary-field quantum Monte Carlo (AFQMC) method, we have studied a two-dimensional tight-binding model in which the conduction electrons can polarize an adjacent layer of molecules through electron-electron repulsion. Calculated average conduction electron density as a function of chemical potential exhibits a clear break characteristic of phase separation. Compared to the noninteracting system, the d-wave pair-field correlation function shows significant enhancement. The simultaneous presence of phase separation and d-wave superconductivity suggests that an effective extended pairing force is induced by the electron-exciton coupling.

Phase separation and d-wave superconductivity induced by extended electron-exciton interaction

International Nuclear Information System (INIS)

Cheng Ming; Su Wupei

2008-01-01

Using an auxiliary-field quantum Monte Carlo (AFQMC) method, we have studied a two-dimensional tight-binding model in which the conduction electrons can polarize an adjacent layer of molecules through electron-electron repulsion. Calculated average conduction electron density as a function of chemical potential exhibits a clear break characteristic of phase separation. Compared to the noninteracting system, the d-wave pair-field correlation function shows significant enhancement. The simultaneous presence of phase separation and d-wave superconductivity suggests that an effective extended pairing force is induced by the electron-exciton coupling

SEE induced in SRAM operating in a superconducting electron linear accelerator environment

Science.gov (United States)

Makowski, D.; Mukherjee, Bhaskar; Grecki, M.; Simrock, Stefan

2005-02-01

Strong fields of bremsstrahlung photons and photoneutrons are produced during the operation of high-energy electron linacs. Therefore, a mixed gamma and neutron radiation field dominates the accelerators environment. The gamma radiation induced Total Ionizing Dose (TID) effect manifests the long-term deterioration of the electronic devices operating in accelerator environment. On the other hand, the neutron radiation is responsible for Single Event Effects (SEE) and may cause a temporal loss of functionality of electronic systems. This phenomenon is known as Single Event Upset (SEU). The neutron dose (KERMA) was used to scale the neutron induced SEU in the SRAM chips. Hence, in order to estimate the neutron KERMA conversion factor for Silicon (Si), dedicated calibration experiments using an Americium-Beryllium (241Am/Be) neutron standard source was carried out. Single Event Upset (SEU) influences the short-term operation of SRAM compared to the gamma induced TID effect. We are at present investigating the feasibility of an SRAM based real-time beam-loss monitor for high-energy accelerators utilizing the SEU caused by fast neutrons. This paper highlights the effects of gamma and neutron radiations on Static Random Access Memory (SRAM), placed at selected locations near the Superconducting Linear Accelerator driving the Vacuum UV Free Electron Laser (VUVFEL) of DESY.

Large electron capture-cross-section of the major nonradiative recombination centers in Mg-doped GaN epilayers grown on a GaN substrate

Science.gov (United States)

Chichibu, S. F.; Shima, K.; Kojima, K.; Takashima, S.; Edo, M.; Ueno, K.; Ishibashi, S.; Uedono, A.

2018-05-01

Complementary time-resolved photoluminescence and positron annihilation measurements were carried out at room temperature on Mg-doped p-type GaN homoepitaxial films for identifying the origin and estimating the electron capture-cross-section ( σ n ) of the major nonradiative recombination centers (NRCs). To eliminate any influence by threading dislocations, free-standing GaN substrates were used. In Mg-doped p-type GaN, defect complexes composed of a Ga-vacancy (VGa) and multiple N-vacancies (VNs), namely, VGa(VN)2 [or even VGa(VN)3], are identified as the major intrinsic NRCs. Different from the case of 4H-SiC, atomic structures of intrinsic NRCs in p-type and n-type GaN are different: VGaVN divacancies are the major NRCs in n-type GaN. The σ n value approximately the middle of 10-13 cm2 is obtained for VGa(VN)n, which is larger than the hole capture-cross-section (σp = 7 × 10-14 cm2) of VGaVN in n-type GaN. Combined with larger thermal velocity of an electron, minority carrier lifetime in Mg-doped GaN becomes much shorter than that of n-type GaN.

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

International Nuclear Information System (INIS)

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

1993-01-01

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

Investigation by high resolution electron spectroscopy of the helium-like 3lnl' Rydberg series in double capture processes at low collision velocity: auto transfer to Rydberg states and electron stabilization

International Nuclear Information System (INIS)

Bordenave-Montesquieu, A.; Moretto-Capelle, P.; Gonzalez, A.; Benhenni, M.; Bachau, H.; Sanchez, I.

1994-01-01

A high resolution electron spectrometry of the (3lnl') Ryberg series populated in N 7+ + He and Ne 10+ + He collisions at 10 q keV, 10 o allows us to observe, for the first time by this method, two post-collisional effects. First, it is found with nitrogen ions that, when n increases from n = 4 to 9, the L-distribution peaks more and more on the high angular momentum states. This is qualitatively understood as a Stark deformation of the Rydberg orbit by the Coulomb field of the receding ion. Also, in the n range where the double capture process populates symmetrical 4l4l' states (n>9), an enhancement of the intensities of the 3lnl' Rydberg lines is observed for both collisonal systems. This is thought to be a signature of the so-called auto transfer to Rydberg states effect. The transfer of population from the 3l4l' to the 3lnl' states is found to be favoured against a direct autoionization of these 4l4l' states into the n = 2 continuum. These experimental findings together with preliminary spectroscopic calculations concerning the configuration interaction of the Ne 8+ (4l4l') states with the Ne 8+ (3lnl') Rydberg series are also discussed within the context of the electron stabilization which follows a double capture. (Author)

Embracing Electronic Publishing.

Science.gov (United States)

Wills, Gordon

1996-01-01

Electronic publishing is the grandest revolution in the capture and dissemination of academic and professional knowledge since Caxton developed the printing press. This article examines electronic publishing, describes different electronic publishing scenarios (authors' cooperative, consolidator/retailer/agent oligopsony, publisher oligopoly), and…

Monte Carlo simulation of positron induced secondary electrons in thin carbon foils

International Nuclear Information System (INIS)

Cai, L H; Yang, B; Ling, C C; Beling, C D; Fung, S

2011-01-01

Emission of secondary electrons induced by the passage of low energy positrons through thin carbon foils was studied by the Monte Carlo method. The positron and electron elastic cross sections were calculated by partial wave analysis. The inelastic positron-valence-electron was described by the energy loss function obtained from dielectric theory. The positron-core-electron interaction was modelled by the Gryzinski's excitation function. Positron transport inside the carbon foil was simulated in detail. Secondary electrons created by positrons and high energy secondary electrons through inelastic interactions were tracked through the foil. The positron transmission coefficient and secondary electron yielded in forward and backward geometry are calculated and dependences on positron energy and carbon foil thickness are discussed.

Evaluation of induced radioactivity in 10 MeV electron-irradiated spices

Energy Technology Data Exchange (ETDEWEB)

Furuta, Masakazu; Ito, Norio; Mizohata, Akira; Matsunami, Tadao; Katayama, Tadashi; Toratani, Hirokazu (Osaka Prefectural Univ., Sakai (Japan). Research Inst. for Advanced Science and Technology); Takeda, Atsuhiko

1993-10-01

In order to make clear appreciation to induced radioactivity in the irradiated foods, photonuclear reactions which could produce radioactivity at energies up to 10 MeV were listed up from elemental compositions of black pepper, white pepper, red pepper, ginger and turmeric. The samples were irradiated with 10 MeV electron from a linear accelerator to a dose of 100 kGy and radioactivity was measured. Induced radioactivity could not be detected significantly by gamma-ray spectrometry and beta-ray counting in the irradiated samples except for spiked samples which contain some photonuclear target nuclides in the list. From the amount of observed radioactivities of short-lived photonuclear products in the spiked samples and calculation of H[sub 50] according to ICRP Publication 30, it was concluded that the induced radioactivity and its biological effects in the 10 MeV electron-irradiated natural samples were negligible in comparison with natural radioactivity from [sup 40]K contained in the samples. (J.P.N.).

Capturing of staphylococcus aureus onto an interface containing graft chains

International Nuclear Information System (INIS)

Lee, W.; Furusaki, Shintaro; Saito, Kyoichi; Sugo, Takanobu; Makuuchi, Keizo.

1995-01-01

A microbial-cell-capturing material was prepared by radiation-induced grafting of glycidyl methacrylate onto a polyethylene-based fiber before the introduction of diethylamine. The prepared fiber was tested against a Staphylococcus aureus and Escherichia coli solution. The results showed that the grafted-type fiber had a capturing rate constant 1000-fold higher than the commercial crosslinked-type bead for S. aureus and that an activation energy of 39 kJ/mol was obtained for the microbial-cell-capturing action. (author)

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

Science.gov (United States)

Nichols, B Nolan; Pohl, Kilian M

2015-09-01

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

Gas chromatographic determination with electron capture detection of residual ethylene oxide in intraocular lenses

Energy Technology Data Exchange (ETDEWEB)

Kikuchi, H.; Nakamura, A.; Tsuji, K.

1988-01-01

A sensitive method is described to determine trace quantities of ethylene oxide (EO) in EO-sterilized intraocular lenses (IOLs). An IOL is dipped in ethanol containing 0.25 ppm propylene oxide (PO) in a 4 mL vial, 2 drops of freshly distilled hydrobromic acid is added through a septum, and the mixture is warmed at 50/sup 0/C for 24 h. It is then neutralized by vigorous shaking with sodium bicarbonate, dehydrated with anhydrous sodium sulfate, and filtered. The filtrate is injected into a gas chromatograph with electron-capture detection, and the peak height ratio of ethylene bromohydrin/propylene bromohydrin is measured. EO residue is calculated from the calibration curve obtained through a similar procedure with the standard EO/PO solutions. The limit of determination is 0.04 ..mu..g/lens (ca 2.0 ppm). When EO residue levels were determined for IOLs sampled at 3 different aeration periods after stabilization, the authors found that 9 days of aeration was necessary to meet the US Food and Drug Administration proposed limit for EO residue in IOLs.

Proteomic analysis of cellular response induced by boron neutron capture reaction in human squamous cell carcinoma SAS cells

International Nuclear Information System (INIS)

Sato, Akira; Itoh, Tasuku; Imamichi, Shoji; Kikuhara, Sota; Fujimori, Hiroaki; Hirai, Takahisa; Saito, Soichiro; Sakurai, Yoshinori; Tanaka, Hiroki; Nakamura, Hiroyuki; Suzuki, Minoru

2015-01-01

To understand the mechanism of cell death induced by boron neutron capture reaction (BNCR), we performed proteome analyses of human squamous tumor SAS cells after BNCR. Cells were irradiated with thermal neutron beam at KUR after incubation under boronophenylalanine (BPA)(+) and BPA(−) conditions. BNCR mainly induced typical apoptosis in SAS cells 24 h post-irradiation. Proteomic analysis in SAS cells suggested that proteins functioning in endoplasmic reticulum, DNA repair, and RNA processing showed dynamic changes at early phase after BNCR and could be involved in the regulation of cellular response to BNCR. We found that the BNCR induces fragments of endoplasmic reticulum-localized lymphoid-restricted protein (LRMP). The fragmentation of LRMP was also observed in the rat tumor graft model 20 hours after BNCT treatment carried out at the National Nuclear Center of the Republic of Kazakhstan. These data suggest that dynamic changes of LRMP could be involved during cellular response to BNCR. - Highlights: • BNCR in human squamous carcinoma cells caused typical apoptotic features. • BNCR induced fragments of LRMP, in human squamous carcinoma and rat tumor model. • The fragmentation of LRMP could be involved in cellular response to BNCR.

Radiative muon capture on nuclei and protons

International Nuclear Information System (INIS)

Azuelos, G.; Gorringe, T.P.; Henderson, R.; Macdonald, J.A.; Poutissou, J.M.; Azuelos, G.; Depommier, P.; Poutissou, R.; Ahmad, S.; Burnham, A.; Hasinoff, M.D.; Larabee, A.J.; Waltham, C.E.; Wright, D.H.; Armstrong, D.S.; Blecher, M.; Serna-Angel, A.; Bertl, W.; Chen, C.Q.; Zhang, N.S.; McDonald, S.C.; Taylor, G.N.; Robertson, B.C.

1990-01-01

A brief review is made of the study of gp, the induced pseudoscalar coupling constant, in radiative muon capture on light nuclei, and of motivations for a measurement on hydrogen, with particular emphasis on recent and ongoing experiments at TRIUMF [fr

Unconscious Attentional Capture Effect Can be Induced by Perceptual Learning

Directory of Open Access Journals (Sweden)

Zhe Qu

2011-05-01

Full Text Available Previous ERP studies have shown that N2pc serves as an index for salient stimuli that capture attention, even if they are task irrelevant. This study aims to investigate whether nonsalient stimuli can capture attention automatically and unconsciously after perceptual learning. Adult subjects were trained with a visual search task for eight to ten sessions. The training task was to detect whether the target (triangle with one particular direction was present or not. After training, an ERP session was performed, in which subjects were required to detect the presence of either the trained triangle (i.e., the target triangle in the training sessions or an untrained triangle. Results showed that, while the untrained triangle did not elicit an N2pc effect, the trained triangle elicited a significant N2pc effect regardless of whether it was perceived correctly or not, even when it was task irrelevant. Moreover, the N2pc effect for the trained triangle was completely retained 3 months later. These results suggest that, after perceptual learning, previously unsalient stimuli become more salient and can capture attention automatically and unconsciously. Once the facilitating process of the unsalient stimulus has been built up in the brain, it can last for a long time.

Radiative muon capture on hydrogen

International Nuclear Information System (INIS)

Schott, W.; Ahmad, S.; Chen, C.Q.; Gumplinger, P.; Hasinoff, M.D.; Larabee, A.J.; Sample, D.G.; Zhang, N.S.; Armstrong, D.S.; Blecher, M.; Serna-Angel, A.; Azuelos, G.; von Egidy, T.; Macdonald, J.A.; Poutissou, J.M.; Poutissou, R.; Wright, D.H.; Henderson, R.S.; McDonald, S.C.; Taylor, G.N.; Doyle, B.; Depommier, P.; Jonkmans, G.; Bertl, W.; Gorringe, T.P.; Robertson, B.C.