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Sample records for elastic charge-exchange differential

  1. Charge exchange system

    DOEpatents

    Anderson, Oscar A.

    1978-01-01

    An improved charge exchange system for substantially reducing pumping requirements of excess gas in a controlled thermonuclear reactor high energy neutral beam injector. The charge exchange system utilizes a jet-type blanket which acts simultaneously as the charge exchange medium and as a shield for reflecting excess gas.

  2. The ratio R{sub dp} of the quasielastic nd {yields} p(nn) to the elastic np {yields} pn charge-exchange-process yields at the proton emitting angle {theta}{sub p,lab} = 0 deg. over 0.55-2.0 GeV neutron beam energy region. Experimental results

    SciTech Connect

    Sharov, V. I. Morozov, A. A.; Shindin, R. A.; Antonenko, V. G.; Borzakov, S. B.; Borzunov, Yu. T.; Chernykh, E. V.; Chumakov, V. F.; Dolgii, S. A.; Finger, M.; Finger, M.; Golovanov, L. B.; Guriev, D. K.; Janata, A.; Kirillov, A. D.; Kovalenko, A. D.; Krasnov, V. A.; Kuzmin, N. A.; Kurilkin, A. K.; Kurilkin, P. K.

    2009-06-15

    New experimental results on ratio R{sub dp} of the quasielastic charge-exchange yield at the outgoing proton angle {theta}{sub p,lab} = 0 deg. for the nd {yields} p(nn) reaction to the elastic np {yields} pn charge-exchange yield, are presented. The measurements were carried out at the Nuclotron of the Veksler and Baldin Laboratory of High Energies of the JINR (Dubna) at the neutron-beam kinetic energies of 0.55, 0.8, 1.0, 1.2, 1.4, 1.8, and 2.0 GeV. The intense neutron beam with small momentum spread was produced by breakup of deuterons which were accelerated and extracted to the experimental hall. In both reactions mentioned above the outgoing protons with the momenta p{sub p} approximately equal to the neutron-beam momentum p{sub n,beam} were detected in the directions close to the direction of incident neutrons, i.e., in the vicinity of the scattering angle {theta}{sub p,lab} = 0 deg. Measured in the same data-taking runs, the angular distributions of the charge-exchange-reaction products were corrected for the well-known instrumental effects and averaged in the vicinity of the incident-neutron-beam direction. These corrected angular distributions for every of nd {yields} p(nn) and np {yields} pn charge-exchange processes were proportional to the differential cross sections of the corresponding reactions. The data were accumulated by Delta-Sigma setup magnetic spectrometer with two sets of multiwire proportional chambers located upstream and downstream of the momentum analyzing magnet. Inelastic processes were considerably reduced by the additional detectors surrounding the hydrogen and deuterium targets. The time-of-flight system was applied to identify the detected particles. The accumulated data treatment and analysis, as well as possible sources of the systematic errors are discussed.

  3. Charge exchange molecular ion source

    DOEpatents

    Vella, Michael C.

    2003-06-03

    Ions, particularly molecular ions with multiple dopant nucleons per ion, are produced by charge exchange. An ion source contains a minimum of two regions separated by a physical barrier and utilizes charge exchange to enhance production of a desired ion species. The essential elements are a plasma chamber for production of ions of a first species, a physical separator, and a charge transfer chamber where ions of the first species from the plasma chamber undergo charge exchange or transfer with the reactant atom or molecules to produce ions of a second species. Molecular ions may be produced which are useful for ion implantation.

  4. The Ratio R{sub dp} of the quasielastic nd {yields} p(nn) to the elastic np {yields} pn charge-exchange-process yields at the proton emitting angle {theta}{sub p,lab} = 0 deg. over 0.55-2.0 GeV neutron-beam energy region. Comparison of the results with the model-dependent calculations

    SciTech Connect

    Sharov, V. I. Morozov, A. A.; Shindin, R. A.; Chernykh, E. V.; Nomofilov, A. A.; Strunov, L. N.

    2009-06-15

    Our new experimental results (see, e.g., Preprint JINR no. E1-2008-61 (Dubna, 2008)) on ratio R{sub dp} of the quasielastic charge-exchange yield at the proton emitting angle {theta}{sub p,lab} = 0 deg. for the nd {yields} p(nn) reaction to the elastic np {yields} pn charge-exchange yield were presented. The measurements were carried out at the Nuclotron of the Veksler and Baldin Laboratory of High Energies of the JINR (Dubna) at the neutron-beam kinetic energies of 0.55, 0.8, 1.0, 1.2, 1.4, 1.8, and 2.0 GeV. In this paper the comparison of the experimental R{sub dp} data with the obtained R{sub dp} calculations within the impulse approximation by using the invariant-amplitude sets from the GW/VPI phase-shift analysis is made. The R{sub dp} values calculated using the set of invariant amplitude data for the elastic np {yields} pn charge exchange at {theta}{sub p,CM} = 0 deg., agree with the experimental data. This confirmed the nd {yields} p(nn) process yield at {theta}{sub p,CM} = 0 deg. is caused by the contribution of the spin-dependent part of the elastic np {yields} pn charge-exchange reaction. Thus, it has been shown that the obtained experimental R{sub dp} results can be used for the Delta-Sigma experimental program to reduce the total ambiguity in the extraction of the amplitude real parts.

  5. Systematics of pion double charge exchange

    SciTech Connect

    Gilman, R.A.

    1985-10-01

    Differential cross sections have been measured for pion-induced double-charge-exchange (DCX) reactions leading to double-isobaric-analog states (DIAS) and low-lying nonanalog states in the residual nuclei. A description of the experimental details and data analysis is presented. The experimentally observed systematics of reactions leading to DIAS, to nonanalog ground states, and to low-lying 2 states are described. Lowest-order optical-model calculations of DIAS DCX are compared to the data. Efforts to understand the anomalies by invoking additional reaction-mechanism amplitudes and a higher-order optical potential are described. Calculations of nonanalog DCX reactions leading to J/sup / = 0 states were performed within a distorted-wave impulse-approximation framework. The sensitivities of these calculations to input parameters are discussed. 58 refs., 41 figs., 16 tabs.

  6. PLT and PDX perpendicular charge exchange analyzers

    NASA Astrophysics Data System (ADS)

    Mueller, D.; Hammett, G. W.; McCune, D. C.

    1986-08-01

    The perpendicular charge-exchange systems used on the poloidal divertor experiment and the Princeton large torus are comprised of ten-channel, mass-resolved, charge-exchange analyzers. Results from these systems indicate that instrumental effects can lead to erroneous temperature measurements during deuterium neutral beam injection or at low hydrogen concentrations.

  7. Charge exchange in H^+ + He^+ collision

    NASA Astrophysics Data System (ADS)

    Guevara Leon, Nicolais; Sabin, John R.; Deumens, Erik; Ohrn, Yngve

    2008-05-01

    Charge exchange in H^+ + He^+ collision are investigated theoretically at projectile energies below the ionization threshold at about 100 keV/amu. The electron nuclear dynamics (END) method is used to analyze the collision processes. Total charge exchange cross sections were calculated and compared with other theoretical and experimental data.

  8. Charge exchange in zinc-neon

    NASA Technical Reports Server (NTRS)

    Chubb, D. L.

    1975-01-01

    Excitation of the 4d and 5p levels of Zn+ by charge exchange bewteen Ne+ and Zn was investigated. From measured electron temperature and line intensity ratios it was concluded that charge exchange is the dominate mechanism for populating the 4d2D5/2 level of Zn+. Comparison of Zn-Ne and Zn-Ar results imply the same conclusion. No evidence for charge exchange as the dominant pumping mechanism for the 5p2Pl/2, 5p2P3/2, or 4d2D3/2 levels was obtained.

  9. Facility produced charge-exchange ions

    NASA Technical Reports Server (NTRS)

    Carruth, M. R., Jr.

    1981-01-01

    These facility produced ions are created by charge-exchange collisions between neutral atoms and energetic thruster beam ions. The result of the electron transfer is an energetic neutral atom and an ion of only thermal energy. There are true charge-exchange ions produced by collisions with neutrals escaping from the ion thruster and being charge-exchange ionized before the neutral intercepts the tank wall. The facility produced charge-exchange ions will not exist in space and therefore, represent a source of error where measurements involving ion thruster plasmas and their density are involved. The quantity of facility produced ions in a test chamber with a 30 cm mercury ion thruster was determined.

  10. Ionosphere-exosphere coupling through charge exchange and momentum transfer in hydrogen-proton collisions

    NASA Technical Reports Server (NTRS)

    Hodges, R. R., Jr.; Breig, E. L.

    1991-01-01

    The implications of a traditional assumption of exospheric physics, that collisions of hydrogen atoms and protons preferentially result in charge exchange with negligible momentum transfer are examined. Initially adopted as a necessary convenience to accommodate limited computer resources in exosphere model calculations, this approximation results in a direct transformation of the proton velocity distribution into a hot component of neutral hydrogen. With expanding computational facilities, the need for the approximation has passed. As the first step toward its replacement with a realistic, quantum mechanical model of the H - H(+) collision process, differential and cumulative cross sections were calculated for quantum elastic scattering of indistinguishable nuclei for a fine grid of encounter energies and scattering angles. These data are used to study the nature of ionosphere-exosphere coupling through H - H(+) collisions, and to demonstrate that the distribution of velocities of scattered H produced in the traditional exospheric charge exchange approximation, as well as that arising from an alternative, fluid dynamic approach, leads to unacceptable abundances of coronal atoms in long-term, highly elliptic trajectories.

  11. Pion double charge exchange and hadron dynamics

    SciTech Connect

    Johnson, M.B.

    1991-01-01

    This paper will review theoretical results to show how pion double charge exchange is contributing to our understanding of hadron dynamics in nuclei. The exploitation of the nucleus as a filter is shown to be essential in facilitating the comparison between theory and experiment. 23 refs., 3 figs., 2 tabs.

  12. Toward a cold hybrid-trap measurement of charge-exchange between Na and Ca+: Na excited state fraction

    NASA Astrophysics Data System (ADS)

    Wells, James E.; Goodman, Douglas S.; Kwolek, Jonathan M.; Blumel, Reinhold; Narducci, Frank A.; Smith, Winthrop W.

    2015-05-01

    We present progress towards the measurement of the charge-exchange collision rate coefficient between neutral sodium and ionic calcium. The rate constant for charge exchange between ground state sodium and calcium ion has been previously calculated and predicts a lifetime in our system of the order of days. Experiments by our group show a much larger charge exchange collision rate, probably from the excited 3P state of sodium. Therefore, an accurate measurement of the charge exchange collision rate constant will require an accurate value for the excited state fraction of the Na MOT. We have developed a technique for making a model-independent measurement of the excited state fraction of a MOT inside a hybrid trap. We compare the measured excited state fraction using this technique with measurements assuming a two-level model of the atom. In addition, we review our recent measurement of the total elastic and resonant charge exchange collision rate between Na and Na+.

  13. Ring current proton decay by charge exchange

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Hoffman, R. A.; Fritz, T.

    1975-01-01

    Explorer 45 measurements during the recovery phase of a moderate magnetic storm have confirmed that the charge exchange decay mechanism can account for the decay of the storm-time proton ring current. Data from the moderate magnetic storm of 24 February 1972 was selected for study since a symmetrical ring current had developed and effects due to asymmetric ring current losses could be eliminated. It was found that after the initial rapid decay of the proton flux, the equatorially mirroring protons in the energy range 5 to 30 keV decayed throughout the L-value range of 3.5 to 5.0 at the charge exchange decay rate calculated by Liemohn. After several days of decay, the proton fluxes reached a lower limit where an apparent equilibrium was maintained, between weak particle source mechanisms and the loss mechanisms, until fresh protons were injected into the ring current region during substorms. While other proton loss mechanisms may also be operating, the results indicate that charge exchange can entirely account for the storm-time proton ring current decay, and that this mechanism must be considered in all studies involving the loss of proton ring current particles.

  14. Charge-exchange plasma environment for an ion drive spacecraft

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.; Carruth, M. R., Jr.

    1981-01-01

    A model was reviewed which describes the propagation of the mercury charge-exchange plasma and extended to describe the flow of the molybdenum component of the charge-exchange plasma. The uncertainties in the models for various conditions are discussed. Such topics as current drain to the solar array, charge-exchange plasma material deposition, and the effects of space plasma on the charge-exchange plasma propagation are addressed.

  15. Positron interactions with water-total elastic, total inelastic, and elastic differential cross section measurements.

    PubMed

    Tattersall, Wade; Chiari, Luca; Machacek, J R; Anderson, Emma; White, Ron D; Brunger, M J; Buckman, Stephen J; Garcia, Gustavo; Blanco, Francisco; Sullivan, James P

    2014-01-28

    Utilising a high-resolution, trap-based positron beam, we have measured both elastic and inelastic scattering of positrons from water vapour. The measurements comprise differential elastic, total elastic, and total inelastic (not including positronium formation) absolute cross sections. The energy range investigated is from 1 eV to 60 eV. Comparison with theory is made with both R-Matrix and distorted wave calculations, and with our own application of the Independent Atom Model for positron interactions.

  16. Ion thruster charge-exchange plasma flow

    NASA Technical Reports Server (NTRS)

    Carruth, M. R., Jr.; Gabriel, S. B.; Kitamura, S.

    1982-01-01

    The electron bombardment ion thruster has been under development for a number of years and during this time, studies of the plasmas produced by the thrusters and their interactions with spacecraft have been evaluated, based on available data. Due to diagnostic techniques used and facility effects, there is uncertainty as to the reliability of data from these early studies. This paper presents data on the flow of the charge-exchange plasma produced just downstream of the thruster's ion optics. The 'end-effect' of a cylindrical Langmuir probe is used to determine ion density and directed ion velocity. Results are compared with data obtained from a retarding potential analyzer-Faraday cup.

  17. Charge exchange avalanche at the cometopause

    NASA Technical Reports Server (NTRS)

    Gombosi, Tamas I.

    1987-01-01

    A sharp transition from a solar wind proton dominated flow to a plasma population primarily consisting of relatively cold cometary heavy ions has been observed at a cometocentric distance of about 160,000 km by the VEGA and GIOTTO missions. This boundary (the cometopause) was thought to be related to charge transfer processes, but its location and thickness are inconsistent with conventionally estimated ion - neutral coupling boundaries. In this paper a two-fluid model is used to investigate the major physical processes at the cometopause. By adopting observed comet Halley parameters the model is able to reproduce the location and the thickness of this charge exchange boundary.

  18. Solar Wind Charge Exchange During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Robertson, Ina P.; Cravens, Thomas E.; Sibeck, David G.; Collier, Michael R.; Kuntz, K. D.

    2012-01-01

    On March 31st. 2001, a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 RE. The NASA/GSFC Community Coordinated Modeling Center (CCMe) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et aL then modeled the expected 50ft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on July 14, 2000 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

  19. Visible charge exchange recombination spectroscopy on TFTR

    SciTech Connect

    Stratton, B.C.; Fonck, R.J.; Jaehnig, K.P.; Schechtman, N.; Synakowski, E.J.

    1991-03-01

    Visible charge exchange recombination spectroscopy is routinely used to measure the time evolution of the ion temperature (T{sub i}) and toroidal rotation velocity (v{sub {phi}}) profiles on TFTR. These measurements are made with the CHERS diagnostic, a fiber-optically coupled spectrometer equipped with a two-dimensional photodiode array detector which provides both spectral and spatial resolution. The instrumentation, data analysis techniques, and examples of T{sub i} and v{sub {phi}} measurements are described. Recently, CHERS has been used to perform impurity transport experiments: radial profiles of diffusivities and convective velocities for helium and iron have been deduced from measurements of the time evolutions of He{sup 2+} and Fe{sup 24+} profiles following impurity injection. Examples of these measurements are given. 12 refs., 8 figs.

  20. Scanning energy analyzer of charge exchange atoms

    SciTech Connect

    Rogozin, A.I.; Shikhovtsev, I.V.

    1994-12-31

    The construction, operation principle, and parameters of multichannel scanning energy analyzer of charge exchange atoms are discussed. The analyzer is used to measure the splashing ion angular distribution and energy spectra, the ions being produced in a gas dynamic plasma trap (GDCS) during the injection of powerful atomic hydrogen beam into preliminary produced plasma with density n {approx_equal} 5 {times} 10{sup 13} cm{sup {minus}3}. The parameters of the hydrogen beam are as follows: particle energy -50 keV, equivalent current -250 A, pulse duration -1 ms. The device can be also used for measurements of energy spectra of atomic and charged particle beams in plasma diagnostics, beam physics, and physics of atomic collisions. 4 refs., 4 figs.

  1. Dependence of the charge exchange lifetimes on mirror latitude

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Bewtra, N. K.

    1976-01-01

    The dependence of the charge exchange lifetimes on the mirror latitude for ions mirroring off the geomagnetic equator was re-computed using the improved hydrogen distribution models. The Chamberlain model was used to define the spatial distribution of the neutral hydrogen environment through which the ring current ions traverse. The resultant dependence of the charge exchange lifetime on mirror latitude is best fitted by the approximation that contains the charge exchange lifetime for equatorial particles.

  2. Charge Exchange and Ablation Rates of a Titanium Wire Plasma Corona

    SciTech Connect

    Terry, Robert E.

    2009-01-21

    Wire ablation rates are important features in any examination of precursors or transparent mode implosions of wire arrays. When ion temperatures in a Ti wire plasma corona exceed a few eV, the process of resonant charge exchange competes with elastic scattering. Ions pushed into the corona from an anode bias wire array can be expected to drive a fast neutral wind into the surrounding volume, while a cathode bias wire array would not show the strong neutral wind.

  3. Energy straggling of low-energy ion beam in a charge exchange cell for negative ion production

    SciTech Connect

    Takeuchi, S.; Sasao, M.; Sugawara, H.; Tanaka, N.; Kisaki, M.; Okamoto, A.; Shinto, K.; Kitajima, S.; Nishiura, M.; Wada, M.

    2008-02-15

    Energy straggling in a charge exchange cell, which is frequently used for negative ion production, was studied experimentally and compared with the results of theoretical evaluation. The change of the energy spectrum of a He{sup +} beam due to charge exchange processes in argon gas was measured in the energy range of 2-6 keV. Energy straggling by multiple collisions is expressed by the energy loss formula due to inelastic and elastic processes. The impact parameter is related to the elastic scattering angle, and the geometry of the charge exchange cell and other components of the beam transportation system determines the maximum acceptable scattering angle. The energy spread was evaluated taking the integral limit over the impact parameter into consideration. The theoretical results showed good agreement with those of actual measurement.

  4. PLT and PDX perpendicular charge-exchange analyzers

    SciTech Connect

    Mueller, D.; Hammett, G.W.; McCune, D.C.

    1986-08-01

    The perpendicular charge-exchange systems used on the poloidal divertor experiment and the Princeton large torus are comprised of ten-channel, mass-resolved, charge-exchange analyzers. Results from these systems indicate that instrumental effects can lead to erroneous temperature measurements during deuterium neutral beam injection or at low hydrogen concentrations.

  5. Suzaku Observations of Charge Exchange Emission from Solar System Objects

    NASA Technical Reports Server (NTRS)

    Ezoe, Y.; Fujimoto, R.; Yamasaki, N. Y.; Mitsuda, K.; Ohashi, T.; Ishikawa, K.; Oishi, S.; Miyoshi, Y; Terada, N.; Futaana, Y.; Porter, F. S.; Brown, G. V.

    2012-01-01

    Recent results of charge exchange emission from solar system objects observed with the Japanese Suzaku satellite are reviewed. Suzaku is of great importance to investigate diffuse X-ray emission like the charge exchange from planetary exospheres and comets. The Suzaku studies of Earth's exosphere, Martian exosphere, Jupiter's aurorae, and comets are overviewed.

  6. Double charge exchange at high impact energies

    NASA Astrophysics Data System (ADS)

    Belkić, Dževad

    1994-03-01

    In fast ion-atom collisions, double ionization always dominates the two-electron transfer. For this reason, an adequate description of double charge exchange requires proper inclusion of intermediate ionization channels. This is even more important in two- than in one-electron transitions. First-order Born-type perturbation theories ignore throughout these electronic continuum intermediate states and hence provide utterly unreliable high energy cross sections for two-electron capture processes. Therefore, it is essential to use second- and higher-order theories, which include the intermediate ionization continua of the two electrons in an approximate manner. In the present paper, a new second-order theory called the Born distorted wave (BDW) approximation is introduced and implemented in the case of symmetric resonant double electron capture from the ground state of helium by fast alpha particles. A genuine four-body formalism is adopted, in contrast to the conventional independent particle model of atomic scattering theory. The obtained results for the total cross sections are compared with the available experimental data, and satisfactory agreement is recorded. As the incident energy increases, a dramatic improvement is obtained in going from the CB1 to the BDW approximation, since the latter closely follows the measurement, whereas the former overestimates the observed total cross sections by two orders of magnitude. This strongly indicates that the role of continuum intermediate states is decisive, even at those incident energies for which the Thomas double scattering effects are not important. This is in sharp contrast to the case of one-electron transfer atomic reactions.

  7. Inversion problem for ion-atom differential elastic scattering.

    NASA Technical Reports Server (NTRS)

    Rich, W. G.; Bobbio, S. M.; Champion, R. L.; Doverspike, L. D.

    1971-01-01

    The paper describes a practical application of Remler's (1971) method by which one constructs a set of phase shifts from high resolution measurements of the differential elastic scattering of protons by rare-gas atoms. These JWKB phase shifts are then formally inverted to determine the corresponding intermolecular potentials. The validity of the method is demonstrated by comparing an intermolecular potential obtained by direct inversion of experimental data with a fairly accurate calculation by Wolniewicz (1965).

  8. Low-energy elastic differential scattering of He/++/ by He.

    NASA Technical Reports Server (NTRS)

    Lam, S. K.; Doverspike, L. D.; Champion, R. L.

    1973-01-01

    Experimental results are developed for the relative elastic differential scattering of He(++) by He for collision energies in the range 4 equal to or less than E equal to or less than 75 eV. In the analysis of the data, semiclassical considerations are utilized, assuming that the dynamics of the scattering is governed solely by the B and E states of He2(++). It is shown that existing ab initio calculations for the intermolecular potentials predict differential cross sections which are not in particularly good agreement with the experimental data.

  9. Charge-exchange plasma generated by an ion thruster

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.

    1977-01-01

    The charge exchange plasma generated by an ion thruster was investigated experimentally using both 5 cm and 15 cm thrusters. Results are shown for wide ranges of radial distance from the thruster and angle from the beam direction. Considerations of test environment, as well as distance from the thruster, indicate that a valid simulation of a thruster on a spacecraft was obtained. A calculation procedure and a sample calculation of charge exchange plasma density and saturation electron current density are included.

  10. Charge exchange dp → (pp)n reaction study at 1.75 A GeV/c by the STRELA spectrometer

    NASA Astrophysics Data System (ADS)

    Basilev, S. N.; Bushuev, Yu. P.; Glagolev, V. V.; Dolgiy, S. A.; Kirillov, D. A.; Kostyaeva, N. V.; Kovalenko, A. D.; Livanov, A. N.; Manyakov, P. K.; Martinská, G.; Mušinský, J.; Piskunov, N. M.; Povtoreiko, A. A.; Rukoyatkin, P. A.; Shindin, R. A.; Sitnik, I. M.; Slepnev, V. M.; Slepnev, I. V.; Urbán, J.

    2016-02-01

    The differential cross sections of the charge exchange reaction dp → (pp)n has been measured at 1.75 GeV/c momentum per nucleon for small transferred momenta using the one arm magnetic spectrometer STRELA at the Nuclotron accelerator. The ratio of the differential cross section of the charge exchange reaction dp → (pp)n to that of the np → pn elementary process is discussed in order to estimate the spin-dependent part of the np → pn charge exchange amplitude on the basis of dp → (pp)n data. The np → pn amplitude turned out to be predominantly spin-dependent.

  11. Myelinating glia differentiation is regulated by extracellular matrix elasticity

    PubMed Central

    Urbanski, Mateusz M.; Kingsbury, Lyle; Moussouros, Daniel; Kassim, Imran; Mehjabeen, Saraf; Paknejad, Navid; Melendez-Vasquez, Carmen V.

    2016-01-01

    The mechanical properties of living tissues have a significant impact on cell differentiation, but remain unexplored in the context of myelin formation and repair. In the PNS, the extracellular matrix (ECM) incorporates a basal lamina significantly denser than the loosely organized CNS matrix. Inhibition of non-muscle myosin II (NMII) enhances central but impairs peripheral myelination and NMII has been implicated in cellular responses to changes in the elasticity of the ECM. To directly evaluate whether mechanotransduction plays a role in glial cell differentiation, we cultured Schwann cells (SC) and oligodendrocytes (OL) on matrices of variable elastic modulus, mimicking either their native environment or conditions found in injured tissue. We found that a rigid, lesion-like matrix inhibited branching and differentiation of OL in NMII-dependent manner. By contrast, SC developed normally in both soft and stiffer matrices. Although SC differentiation was not significantly affected by changes in matrix stiffness alone, we found that expression of Krox-20 was potentiated on rigid matrices at high laminin concentration. These findings are relevant to the design of biomaterials to promote healing and regeneration in both CNS and PNS, via transplantation of glial progenitors or the implantation of tissue scaffolds. PMID:27646171

  12. Myelinating glia differentiation is regulated by extracellular matrix elasticity.

    PubMed

    Urbanski, Mateusz M; Kingsbury, Lyle; Moussouros, Daniel; Kassim, Imran; Mehjabeen, Saraf; Paknejad, Navid; Melendez-Vasquez, Carmen V

    2016-01-01

    The mechanical properties of living tissues have a significant impact on cell differentiation, but remain unexplored in the context of myelin formation and repair. In the PNS, the extracellular matrix (ECM) incorporates a basal lamina significantly denser than the loosely organized CNS matrix. Inhibition of non-muscle myosin II (NMII) enhances central but impairs peripheral myelination and NMII has been implicated in cellular responses to changes in the elasticity of the ECM. To directly evaluate whether mechanotransduction plays a role in glial cell differentiation, we cultured Schwann cells (SC) and oligodendrocytes (OL) on matrices of variable elastic modulus, mimicking either their native environment or conditions found in injured tissue. We found that a rigid, lesion-like matrix inhibited branching and differentiation of OL in NMII-dependent manner. By contrast, SC developed normally in both soft and stiffer matrices. Although SC differentiation was not significantly affected by changes in matrix stiffness alone, we found that expression of Krox-20 was potentiated on rigid matrices at high laminin concentration. These findings are relevant to the design of biomaterials to promote healing and regeneration in both CNS and PNS, via transplantation of glial progenitors or the implantation of tissue scaffolds. PMID:27646171

  13. Helium escape from the Earth's atmosphere - The charge exchange mechanism revisited

    NASA Technical Reports Server (NTRS)

    Lie-Svendsen, O.; Rees, M. H.; Stamnes, K.

    1992-01-01

    We have studied the escape of neutral helium from the terrestrial atmosphere through exothermic charge exchange reactions between He(+) ions and the major atmospheric constituents N2, O2 and O. Elastic collisions with the neutral background particles were treated quantitatively using a recently developed kinetic theory approach. An interhemispheric plasma transport model was employed to provide a global distribution of He(+) ions as a function of altitude, latitude and local solar time and for different levels of solar ionization. Combining these ion densities with neutral densities from an MSIS model and best estimates for the reaction rate coefficients of the charge exchange reactions, we computed the global distribution of the neutral He escape flux. The escape rates show large diurnal and latitudinal variations, while the global average does not vary by more than a factor of three over a solar cycle. We find that this escape mechanism is potentially important for the overall balance of helium in the Earth's atmosphere. However, more accurate values for the reaction rate coefficients of the charge exchange reactions are required to make a definitive assessment of its importance.

  14. Differential Cross Sections for Proton-Proton Elastic Scattering

    NASA Technical Reports Server (NTRS)

    Norman, Ryan B.; Dick, Frank; Norbury, John W.; Blattnig, Steve R.

    2009-01-01

    Proton-proton elastic scattering is investigated within the framework of the one pion exchange model in an attempt to model nucleon-nucleon interactions spanning the large range of energies important to cosmic ray shielding. A quantum field theoretic calculation is used to compute both differential and total cross sections. A scalar theory is then presented and compared to the one pion exchange model. The theoretical cross sections are compared to proton-proton scattering data to determine the validity of the models.

  15. Charge Exchange Spectra of Hydrogenic and He-like Iron

    SciTech Connect

    Wargelin, B J; Beiersdorfer, P; Neill, P A; Olson, R E; Scofield, J H

    2005-04-27

    We present H-like Fe XXVI and He-like Fe XXV charge-exchange spectra resulting from collisions of highly charged iron with N{sub 2} gas at an energy of {approx}10 eV amu{sup -1} in an electron beam ion trap. Although high-n emission lines are not resolved in our measurements, we observe that the most likely level for Fe{sup 25+} {yields} Fe{sup 24+} electron capture is n{sub max} {approx} 9, in line with expectations, while the most likely value for Fe{sup 26+} {yields} Fe{sup 25+} charge exchange is significantly higher. In the Fe XXV spectrum, the K{alpha} emission feature dominates, whether produced via charge exchange or collisional excitation. The K{alpha} energy centroid is lower in the former case than the latter (6666 versus 6685 eV, respectively), as expected because of the strong enhancement of emission from the forbidden and intercombination lines, relative to the resonance line, in charge-exchange spectra. In contrast, the Fe XXVI high-n Lyman lines have a summed intensity greater than that of Ly{alpha}, and are substantially stronger than predicted from theoretical calculations of charge exchange with atomic H. A discussion is presented of the relevance of our results to studies of diffuse Fe emission in the Galactic Center and Galactic Ridge, particularly with ASTRO-E2.

  16. Signatures of the electron saddle swaps mechanism in the photon spectra following charge-exchange collisions

    NASA Astrophysics Data System (ADS)

    Otranto, Sebastian

    2014-10-01

    During the last few years, several experimental and theoretical studies have focused on state selective charge exchange processes between charged ions and alkali metals. These data are of particular importance for the tokamak nuclear fusion reactor program, since diagnostics on the plasma usually rely on charge-exchange spectroscopy. In this sense, alkali metals, have been proposed as potential alternatives to excited hydrogen/deuterium for which laboratory experiments are not feasible at present. In this talk, we present our recent work involving ion collisions with alkali metals. Oscillatory structures in the angular differential charge-exchange cross sections obtained using the MOTRIMS technique are correctly described by classical trajectory Monte Carlo simulations. These oscillations are found to originate from the number of swaps the electron undergoes around the projectile-target potential saddle before capture takes place and are very prominent at impact energies below 10 keV/amu. Moreover, cross sections of higher order of differentiability also indicate that the swaps leave distinctive signatures in the (n,l)-state selective cross sections and in the photon line emission cross sections. Oscillatory structures for the x-ray hardness ratio parameter are also predicted. In collaboration with Ronnie Hoekstra, Zernike Institute for Advanced Materials, University of Groningen and Ronald Olson, Department of Physics, Missouri University of Science and Technology.

  17. Controlled charge exchange between alkaline earth metals and their ions

    NASA Astrophysics Data System (ADS)

    Gacesa, Marko; Côté, Robin

    2015-05-01

    We theoretically investigate the prospects of realizing controlled charge exchange via magnetic Feshbach resonances in cold and ultracold collisions of atoms and ions. In particular, we focus on near-resonant charge exchange in heteroisotopic combinations of alkaline earth metals, such as 9Be++10 Be<-->9 Be+10Be+ , which exhibit favorable electronic and hyperfine structure. The quantum scattering calculations are performed for a range of initial states and experimentally attainable magnetic fields in standard coupled-channel Feshbach projection formalism, where higher-order corrections such as the mass-polarization term are explicitely included. In addition, we predict a number of magnetic Feshbach resonances for different heteronuclear isotopic combinations of the listed and related alkaline earth elements. Our results imply that near-resonant charge-exchange could be used to realize atom-ion quantum gates, as well as controlled charge transfer in optically trapped cold quantum gases. This work is partially supported by ARO.

  18. Characterization of an atomic hydrogen source for charge exchange experiments

    NASA Astrophysics Data System (ADS)

    Leutenegger, M. A.; Beiersdorfer, P.; Betancourt-Martinez, G. L.; Brown, G. V.; Hell, N.; Kelley, R. L.; Kilbourne, C. A.; Magee, E. W.; Porter, F. S.

    2016-11-01

    We characterized the dissociation fraction of a thermal dissociation atomic hydrogen source by injecting the mixed atomic and molecular output of the source into an electron beam ion trap containing highly charged ions and recording the x-ray spectrum generated by charge exchange using a high-resolution x-ray calorimeter spectrometer. We exploit the fact that the charge exchange state-selective capture cross sections are very different for atomic and molecular hydrogen incident on the same ions, enabling a clear spectroscopic diagnostic of the neutral species.

  19. Neutral Collisions and Charge Exchange in Titan's Exosphere

    NASA Astrophysics Data System (ADS)

    Sillanpää, I.; Johnson, R. E.

    2012-12-01

    Results from new hybrid simulations for Titan are presented. These simulations take into account the elastic collisions between ions and neutral gas as well as the charge exchange reactions for protons and oxygen ions. We used SRIM [1] cross sections for hydrogen and oxygen ions in nitrogen gas to calculate cross sections for the five ions species used in the HYB-Titan hybrid model [2, see also 3] (H+, H2+, O+, CH4+, and N2+). The N2 density profile used was from INMS measurements over a dozen flybys. In addition, we are studying the effect the charge transfer (CT) reactions for H+ and O+ leading to simple CT, dissociative CT and CT with ionization. All reaction cross sections are energy dependent. Neutral particles are not created, but the total ENA energy is recorded as well as the resulting reaction rates. The results show that both of neutral collisions and CT processes have a significant role in the development and shape of Titan's ionotail and wake structure. Results will be described in detail as well as the implications of the ion-neutral collisions for the heating of Titan's neutral corona and atmospheric escape [4]. References [1] Stopping and Range of Ions in Matter (SRIM), Monte Carlo software by James F. Ziegler (online at http://www.srim.org/ ) [2] Sillanpää, I., Hybrid Modelling of Titan's Interaction with the Magnetosphere of Saturn, Ph.D. dissertation, Finnish Meteorological Contributions, 68, Yliopistopaino, Helsinki, 2008. (online at http://urn.fi/URN:ISBN:978-951-697-660-3) [3] Sillanpää, I., D. Young, F. Crary, M. Thomsen, D. Reisenfeld, J-E.Wahlund, C. Bertucci, E. Kallio, R. Jarvinen, and P. Janhunen, Cassini Plasma Spectro:meter and Hybrid Model Study on Titan's Interaction: Effect of Oxygen Ions, J. Geophys. Res., doi:10.1029/2011JA016443, 2011. [4] Johnson, R.E., O.J. Tucker, M. Michael, E.C. Sittler, H.T. Smith, D.T. Young, and J.H. Waite, Mass Loss Processes in Titan's Upper Atmosphere, Chap. 15 in "Titan from Cassini-Huygens" (eds

  20. First Charge-Exchange Measurements with SHARAQ

    SciTech Connect

    Miki, K.; Sakai, H.

    2011-10-28

    The isovector spin monopole resonances (IVSMR) of the {beta}{sup +} type were observed for the first time in the {sup 208}Pb and {sup 90}Zr(t,{sup 3}He) reactions at 300 MeV/u. The experiment was performed at the RI Beam Factory (RIBF) at RIKEN by using the newly-constructed magnetic spectrometer SHARAQ. The double differential cross sections for the {sup 208}Pb and {sup 90}Zr(t,{sup 3}He) reactions were obtained at the excitation energy of 0{<=}E{sub x}{<=}70 MeV and the scattering angles of 0 deg. {<=}{theta}{<=}3 deg. The monopole component was identified by making a difference between the zero-degree and backward-angle spectra. The signatures of the IVSMR are observed at an excitation energy of 12 MeV(20 MeV) in {sup 208}Pb({sup 90}Zr)(t,{sup 3}He) reaction, which agrees fairly well with the theoretical predictions.

  1. HIGH CURRENT D- PRODUCTION BY CHARGE EXCHANGE IN SODIUM

    SciTech Connect

    Hooper, E.B.; Poulsen, P.; Pincosy, P.A.

    1981-02-01

    A beam of D{sup -} ions has been produced at 7-13 keV, with currents up to 2.2 {angstrom}, using charge exchange in sodium vapor. The beam profile is bi-Gaussian with angular divergence 0.7{sup o} x 2.8{sup o} and peak current density 15 mA/cm{sup 2}. The characteristics of the beam are in excellent agreement with predictions based on atomic cross sections. The sodium vapor target is formed by a jet directed across the beam. The sodium density drops rapidly in the beamline downstream from the charge exchange region, decreasing three orders of magnitude in 15 cm. Measurement and analysis of the plasma accompanying the beam demonstrate that plasma densities nearly equal to the beam density are obtained 1 m from the charge exchange medium. The plasma produced in the sodium is thus well confined to the charge exchange region and does not propagate along the beam.

  2. Radiocarbon detection by ion charge exchange mass spectrometry

    NASA Astrophysics Data System (ADS)

    Hotchkis, Michael; Wei, Tao

    2007-06-01

    A method for detection of radiocarbon at low levels is described and the results of tests are presented. We refer to this method as ion charge exchange mass spectrometry (ICE-MS). The ICE-MS instrument is a two stage mass spectrometer. In the first stage, molecular interferences which would otherwise affect radiocarbon detection at mass 14 are eliminated by producing high charge state ions directly in the ion source (charge state ⩾2). 14N interference is eliminated in the second stage by converting the beam to negative ions in a charge exchange cell. The beam is mass-analysed at each stage. We have built a test apparatus consisting of an electron cyclotron resonance ion source and a pair of analysing magnets with a charge exchange cell in between, followed by an electrostatic analyser to improve the signal to background ratio. With this apparatus we have measured charge exchange probabilities for (Cn+ → C-) from 4.5 to 40.5 keV (n = 1-3). We have studied the sources of background including assessment of limits for nitrogen interference by searching for negative ions from charge exchange of 14N ions. Our system has been used to detect 14C in enriched samples of CO2 gas with 14C/12C isotopic ratio down to the 10-9 level. Combined with a measured sample consumption rate of 4 ng/s, this corresponds to a capability to detect transient signals containing only a few μBq of 14C activity, such as may be obtained from chromatographic separation. The method will require further development to match the sensitivity of AMS with a gas ion source; however, even in its present state its sensitivity is well suited to tracer studies in biomedical research and drug development.

  3. Charge exchange in solar wind-cometary interactions

    NASA Technical Reports Server (NTRS)

    Gombosi, T. I.; Horanyi, M.; Kecskemety, K.; Cravens, T. E.; Nagy, A. F.

    1983-01-01

    A simple model of a cometary spherically symmetrical atmosphere and ionosphere is considered. An analytic solution of the governing equations describing the radial distribution of the neutral and ion densities is found. The new solution is compared to the well-known solution of the equations containing only ionization terms. Neglecting recombination causes a significant overestimate of the ion density in the vicinity of the comet. An axisymmetric model of the solar wind-cometary interaction is considered, taking into account the loss of solar wind ions due to charge exchange. The calculations predict that for active comets, solar wind absorption due to charge exchange becomes important at a few thousand kilometers from the nucleus, and a surface separating the shocked solar wind from the cometary ionosphere develops in this region. These calculations are in reasonable agreement with the few observations available for the ionopause location at comets.

  4. Pion double charge exchange scattering above the delta resonance

    SciTech Connect

    Burleson, G.R.

    1989-01-01

    Data are presented on pion-nucleus double-charge-exchange scattering at energies between 300 and 500 MeV, the highest energies measured so far, together with a review of results at lower energies. The small-angle excitation functions disagree with predictions based on a sex-quark cluster model and on an optical model consistent with single-charge-exchange scattering at these energies, but they are consistent with a distorted-wave calculation. Data on f{sub 7/2}-shell nuclei are in partial agreement with a two-amplitude model which is successful at lower energies. In order to achieve good understanding of this process at these energies, more work; both experimental and theoretical, is needed. 16 refs., 6 figs.

  5. Mass-resolving charge-exchange system on PDX

    SciTech Connect

    Davis, S.L.; Mueller, D.; Keane, C.J.

    1982-10-01

    The PDX charge-exchange system is comprised of four, ten channel, mass-resolved, charge-exchange analyzers. Each analyzer is constructed with parallel electric and magnetic fields and is calibrated over an energy range of 0.5 to 40 keV. The mass rejection between hydrogen and deuterium has been measured as better than 1000 to 1. For ohmic heated discharges the system can provide single shot radial ion temperature profiles (4 point) with 1 msec time resolution. For neutral beam heated discharges complete radial and temporal profiles can be obtained in 2 to 4 shots. The system is also equipped with a vertically aimed diagnostic neutral beam to allow local ion-energy distribution measurements. This report describes the analyzer system and its calibration, and presents results from ohmic and neutral beam heated discharges.

  6. Coherent population trapping probed by charge exchange reactions

    NASA Astrophysics Data System (ADS)

    Gieler, M.; Aumayr, F.; Windholz, L.

    1992-12-01

    Coherent trapping of atomic population in sodium induced by two-frequency laser light has been studied by using a charge exchange reaction for probing the upper level population. When the two-photon resonance condition occurs, the signal due to electron capture from excited Na*(3p) atoms by He2+ projectile ions exhibits the characteristic ``black resonance'' dip, indicating (by nonoptical means) that the fraction of Na atoms in the excited state actually drops to zero.

  7. Momentum transfer in relativistic heavy ion charge-exchange reactions

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Wilson, J. W.; Khan, F.; Khandelwal, G. S.

    1991-01-01

    Relativistic heavy ion charge-exchange reactions yield fragments (Delta-Z = + 1) whose longitudinal momentum distributions are downshifted by larger values than those associated with the remaining fragments (Delta-Z = 1, -2,...). Kinematics alone cannot account for the observed downshifts; therefore, an additional contribution from collision dynamics must be included. In this work, an optical model description of collision momentum transfer is used to estimate the additional dynamical momentum downshift. Good agreement between theoretical estimates and experimental data is obtained.

  8. Computer code for charge-exchange plasma propagation

    NASA Technical Reports Server (NTRS)

    Robinson, R. S.; Kaufman, H. R.

    1981-01-01

    The propagation of the charge-exchange plasma from an electrostatic ion thruster is crucial in determining the interaction of that plasma with the associated spacecraft. A model that describes this plasma and its propagation is described, together with a computer code based on this model. The structure and calling sequence of the code, named PLASIM, is described. An explanation of the program's input and output is included, together with samples of both. The code is written in ASNI Standard FORTRAN.

  9. Imaging charge exchange recombination spectroscopy on the TEXTOR tokamak

    NASA Astrophysics Data System (ADS)

    Howard, J.; Jaspers, R.; Lischtschenko, O.; Delabie, E.; Chung, J.

    2010-12-01

    We describe the application of a simple spatial-heterodyne coherence-imaging filter for 2D Doppler imaging of charge exchange recombination (CXR) emission from a heating beam in the TEXTOR tokamak. Results obtained by the CXR imaging system are found to be consistent with measurements obtained using a standard multi-channel spectrometer-based system. We describe the system, indicate possible enhancements and future applications for imaging CXRS.

  10. Plasma ion temperature measurements via charge exchange recombination radiation

    NASA Astrophysics Data System (ADS)

    Fonck, R. J.; Goldston, R. J.; Kaita, R.; Post, D. E.

    1983-02-01

    Spatially and temporally resolved plasma ion temperatures can be determined by measuring the Doppler-broadened line profiles of transitions excited by charge-exchange recombination reactions between fast hydrogen atoms and fully ionized low-Z ions. Plasma rotation velocity profiles can also be obtained. A sample result from the PDX tokamak using He+ radiation is presented, and expected line intensities for model cases for PDX and TFTR are calculated.

  11. Plasma ion temperature measurements via charge-exchange recombination radiation

    SciTech Connect

    Fonck, R.J.; Goldston, R.J.; Kaita, R.; Post, D.E.

    1982-11-01

    Spatially and temporally resolved plasma ion temperatures can be determined by measuring the Doppler-broadened line profiles of transitions excited by charge-exchange recombination reactions between fast hydrogen atoms and fully ionized low-Z ions. Plasma rotation velocity profiles can also be obtained. A sample result from the PDX tokamak using He/sup +/ radiation is presented, and expected line intensities for model cases for PDX and TFTR are calculated.

  12. Plasma ion temperature measurements via charge exchange recombination radiation

    SciTech Connect

    Fonck, R.J.; Goldston, R.J.; Kaita, R.; Post, D.E.

    1983-02-01

    Spatially and temporally resolved plasma ion temperatures can be determined by measuring the Doppler-broadened line profiles of transitions excited by charge-exchange recombination reactions between fast hydrogen atoms and fully ionized low-Z ions. Plasma rotation velocity profiles can also be obtained. A sample result from the PDX tokamak using He/sup +/ radiation is presented, and expected line intensities for model cases for PDX and TFTR are calculated.

  13. Krypton charge exchange cross sections for Hall effect thruster models

    SciTech Connect

    Hause, Michael L.; Prince, Benjamin D.; Bemish, Raymond J.

    2013-04-28

    Following discharge from a Hall effect thruster, charge exchange occurs between ions and un-ionized propellant atoms. The low-energy cations produced can disturb operation of onboard instrumentation or the thruster itself. Charge-exchange cross sections for both singly and doubly charged propellant atoms are required to model these interactions. While xenon is the most common propellant currently used in Hall effect thrusters, other propellants are being considered, in particular, krypton. We present here guided-ion beam measurements and comparisons to semiclassical calculations for Kr{sup +} + Kr and Kr{sup 2+} + Kr cross sections. The measurements of symmetric Kr{sup +} + Kr charge exchange are in good agreement with both the calculations including spin-orbit effects and previous measurements. For the symmetric Kr{sup 2+} + Kr reaction, we present cross section measurements for center-of-mass energies between 1 eV and 300 eV, which spans energies not previously examined experimentally. These cross section measurements compare well with a simple one-electron transfer model. Finally, cross sections for the asymmetric Kr{sup 2+} + Kr {yields} Kr{sup +} + Kr{sup +} reaction show an onset near 12 eV, reaching cross sections near constant value of 1.6 A{sup 2} with an exception near 70-80 eV.

  14. Energetic Neutral Atom Production due to Charge Exchange at Mars

    NASA Astrophysics Data System (ADS)

    Friedrich, Erena

    2008-05-01

    An energetic neutral atom (ENA) is formed in a charge exchange process where an energetic ion picks up an electron from a neutral particle. Mars, having no notable global intrinsic magnetic field, cannot shield the neutral particles in its atmosphere from the flow of energetic solar wind protons. Consequently, an extensive production of energetic hydrogen atoms (H-ENAs) occurs. In this study a 3D hybrid (kinetic ions, fluid electrons) quasi-neutral particle-in-cell (PIC) plasma simulation is being developed to investigate the production of H-ENAs due to collisions with atomic oxygen (O) and neutral nitrogen molecules (N2) in the transition region of the Martian near-space environment. In order to better study the interaction between Mars' exosphere and ionosphere, multi-species reactions such as ionization by photons, electron recombination and charge exchange are self-consisitently included in the simulation model. The major ions included are exospheric solar wind protons and the planetary O2^+, CO2^+, O^+, and N2^+ ions. The motion of the precipitating particles in the atmosphere is followed, and collisions with atmospheric ions and neutrals (O, CO2, N2) are governed by a Monte Carlo ``collision-by-collision'' algorithm. What is presented is a ``work in progress'' as we work towards our goal of computing the flux of escaping H-ENAs due to charge exchange with O and N2.

  15. Systematics of heavy-ion charge-exchange straggling

    NASA Astrophysics Data System (ADS)

    Sigmund, P.; Schinner, A.

    2016-10-01

    The dependence of heavy-ion charge-exchange straggling on the beam energy has been studied theoretically for several ion-target combinations. Our previous work addressed ions up to krypton, while the present study focuses on heavier ions, especially uranium. Particular attention has been paid to a multiple-peak structure which has been predicted theoretically in our previous work. For high-Z1 and high-Z2 systems, exemplified by U in Au, we identify three maxima in the energy dependence of charge-exchange straggling, while the overall magnitude is comparable with that of collisional straggling. Conversely, for U in C, charge-exchange straggling dominates, but only two peaks lie in the energy range where we presently are able to produce credible predictions. For U-Al we find good agreement with experiment in the energy range around the high-energy maximum. The position of the high-energy peak - which is related to processes in the projectile K shell - is found to scale as Z12 , in contrast to the semi-empirical Z13/2 dependence proposed by Yang et al. Measurements for heavy ions in heavy targets are suggested in order to reconcile a major discrepancy between the present calculations and the frequently-used formula by Yang et al.

  16. A staggered-grid convolutional differentiator for elastic wave modelling

    NASA Astrophysics Data System (ADS)

    Sun, Weijia; Zhou, Binzhong; Fu, Li-Yun

    2015-11-01

    The computation of derivatives in governing partial differential equations is one of the most investigated subjects in the numerical simulation of physical wave propagation. An analytical staggered-grid convolutional differentiator (CD) for first-order velocity-stress elastic wave equations is derived in this paper by inverse Fourier transformation of the band-limited spectrum of a first derivative operator. A taper window function is used to truncate the infinite staggered-grid CD stencil. The truncated CD operator is almost as accurate as the analytical solution, and as efficient as the finite-difference (FD) method. The selection of window functions will influence the accuracy of the CD operator in wave simulation. We search for the optimal Gaussian windows for different order CDs by minimizing the spectral error of the derivative and comparing the windows with the normal Hanning window function for tapering the CD operators. It is found that the optimal Gaussian window appears to be similar to the Hanning window function for tapering the same CD operator. We investigate the accuracy of the windowed CD operator and the staggered-grid FD method with different orders. Compared to the conventional staggered-grid FD method, a short staggered-grid CD operator achieves an accuracy equivalent to that of a long FD operator, with lower computational costs. For example, an 8th order staggered-grid CD operator can achieve the same accuracy of a 16th order staggered-grid FD algorithm but with half of the computational resources and time required. Numerical examples from a homogeneous model and a crustal waveguide model are used to illustrate the superiority of the CD operators over the conventional staggered-grid FD operators for the simulation of wave propagations.

  17. Differential biomechanical development of elastic tissues in the bovine fetus.

    PubMed

    Walter, E Jane; Wells, Sarah M

    2010-04-01

    Mechanical loading conditions are important factors in the gestational development of fetal tissues. However, little is known about how mechanical loading during development modulates the structure and function of elastic tissues. We hypothesized that developing elastic tissues functionally adapt to their loading conditions. To test this hypothesis, we assessed the changes in the composition, viscoelasticity, and thermoelastic properties of elastic tissue from bovine aortas (functional during gestation) and nuchal ligaments (nonfunctional during gestation). Clear differences in the developmental timeline of elastic tissue structure and function were observed between aortic and ligament elastic tissue. Elastic tissue in the aorta developed earlier than that of the nuchal ligament, indicating a role for loading conditions in the timeline of development. Ligament elastic tissue, however, underwent rapid remodeling in late gestation-likely as a preadaptation to the sudden-onset of tensile load it experiences at birth. Finally, while the same fundamental structure-mechanical relationships were seen in both tissues, there was a clear difference in mechanical properties between the elastic tissues from the adult nuchal ligament and the adult aorta, indicating that postnatal loading conditions continue to influence tissue structure and mechanical properties, tailoring them to their functional roles in adult life.

  18. Solar System X-rays from Charge Exchange Processes

    NASA Astrophysics Data System (ADS)

    Lisse, Carey M.; Christian, D. J.; Bhardwaj, A.; Dennerl, K.; Wolk, S. J.; Bodewits, D.; Combi, M. R.; Zurbuchen, T. H.; Lepri, S. T.

    2013-04-01

    The discovery of high energy x-ray emission in 1996 from comet C/1996 B2 (Hyakutake) uncovered a new class of x-ray emitting objects. Subsequent detections of the morphology, spectra, and time dependence of the x-rays from more than 20 comets have shown that the very soft (E < 1 keV) emission is due to a charge-exchange interaction between highly charged solar wind minor ions and the comet's extended neutral atmosphere. Many solar system objects are now known to shine in the X-ray, including Venus, Mars, the Moon, the Earth, Jupiter, and Saturn, with total power outputs on the MW - GW scale. Like comets, the X-ray emission from the Earth's geo-corona, the Jovian & Saturnian aurorae, and the Martian halo are thought to be driven by charge exchange between highly charged minor (heavy) ions in the solar wind and gaseous neutral species in the bodies' atmosphere. The non-auroral X-ray emissions from Jupiter, Saturn, and Earth, and those from disks of Mars, Venus, and the Moon are produced by scattering of solar X-rays. The first soft X-ray observations of Earth’s aurora by Chandra shows that it is highly variable, and the giant planet aurorae are fascinating puzzles that are just beginning to yield their secrets and may be the only x-ray sources not driven directly by the Sun in the whole system as well as properties of hot exo-solar Jupiters. Observations of local solar system charge exchange processes can also help inform us about x-rays produced at more distant hot ionized gas/cold neutral gas interfaces, like the heliopause, stellar astrospheres, galactic star forming regions, and starburst galaxies.

  19. (p,n) Charge-Exchange Reactions in Inverse Kinematics

    NASA Astrophysics Data System (ADS)

    Lipschutz, Samuel; NSCL E10003 Collaboration

    2014-09-01

    Charge-exchange experiments at intermediate energy yield important information about collective excitations with spin-isospin degrees of freedom. The properties of isovector giant resonances in neutron-rich rare-isotopes provide stringent tests of theoretical models and are important inputs for modeling of astrophysical phenomena. The (p,n) charge-exchange reaction in inverse kinematics has been developed as a new tool for investigating isovector giant resonances in rare isotopes. The technique, which involves the detection of low-energy neutrons that recoil from a hydrogen target, while detecting fast beam-like ejectiles in a magnetic spectrometer, was successfully employed at NSCL to study the 56Ni(p,n) reaction. Continuing with this technique a 16C(p,n) experiment at 100 MeV/u aimed at extracting isovector multipole strengths up to excitation energies of 30 MeV was preformed. The Low Energy Neutron Detector Array (LENDA) and the Versatile Array of Neutron Detectors at Low Energy (VANDLE) were utilized in combination with the Ursinus Liquid Hydrogen Target and the S800 spectrometer to perform this experiment. Preliminary results will be shown. Charge-exchange experiments at intermediate energy yield important information about collective excitations with spin-isospin degrees of freedom. The properties of isovector giant resonances in neutron-rich rare-isotopes provide stringent tests of theoretical models and are important inputs for modeling of astrophysical phenomena. The (p,n) charge-exchange reaction in inverse kinematics has been developed as a new tool for investigating isovector giant resonances in rare isotopes. The technique, which involves the detection of low-energy neutrons that recoil from a hydrogen target, while detecting fast beam-like ejectiles in a magnetic spectrometer, was successfully employed at NSCL to study the 56Ni(p,n) reaction. Continuing with this technique a 16C(p,n) experiment at 100 MeV/u aimed at extracting isovector multipole

  20. Charge-exchange born He(+) ions in the solar wind

    NASA Technical Reports Server (NTRS)

    Gruntman, Michael A.

    1992-01-01

    The effect of charge transfer between solar wind alpha-particles and hydrogen atoms of interstellar origin is revisited. Singly-charged helium ions born in the charge transfer carry important information on processes in the solar wind and the heliosphere. The velocity distribution of such He(+) ions is substantially different from that of He(+) pick-up ions due to ionization of the interstellar helium atoms. Estimates of the expected abundances of the charge-exchange born He(+) in the solar wind are presented, and the possibility of measuring this plasma component on deep space missions is discussed.

  1. Charge exchange reactions and solar neutrino detection in 81Br

    NASA Astrophysics Data System (ADS)

    Liu, K. F.; Gabbard, F.

    1983-01-01

    The feasibility of 81Br as the detector of the solar neutrino flux hinges upon the knowledge of the Gamow-Teller matrix element from the ground state of 81Br to the 52- state at 0.457 MeV in 81Kr. The possibility of obtaining this matrix element is discussed in terms of the (p, n) and (3He, t) charge exchange reactions. NUCLEAR REACTIONS 81Br(p, n)81Kr and 81Br(3He, t)81Kr Gamow-Teller transitions; solar neutrino detection.

  2. Charge-exchange born He(+) ions in the solar wind

    NASA Astrophysics Data System (ADS)

    Gruntman, Michael A.

    1992-07-01

    The effect of charge transfer between solar wind alpha-particles and hydrogen atoms of interstellar origin is revisited. Singly-charged helium ions born in the charge transfer carry important information on processes in the solar wind and the heliosphere. The velocity distribution of such He(+) ions is substantially different from that of He(+) pick-up ions due to ionization of the interstellar helium atoms. Estimates of the expected abundances of the charge-exchange born He(+) in the solar wind are presented, and the possibility of measuring this plasma component on deep space missions is discussed.

  3. Charge-Exchange Excitation of the Isobaric Analog State and Implication for the Nuclear Symmetry Energy and Neutron Skin

    NASA Astrophysics Data System (ADS)

    Khoa, Dao T.; Loc, Bui Minh; Zegers, R. G. T.

    The charge-exchange (p, n) or (3He,t) reaction can be considered as elastic scattering of proton or 3He by the isovector term of the optical potential that flips the projectile isospin. Therefore, the accurately measured charge-exchange scattering cross section for the isobaric analog states can be a good probe of the isospin dependence of the optical potential, which is determined exclusively within the folding model by the difference between the neutron and proton densities and isospin dependence of the nucleon-nucleon interaction. On the other hand, the same isospin- and density-dependent nucleon-nucleon interaction can also be used in a Hartree-Fock calculation of asymmetric nuclear matter, to estimate the nuclear matter energy and its asymmetry part. As a result, the fine-tuning of the isospin dependence of the effective nucleon-nucleon interaction against the measured (p, n) or (3He,t) cross sections should allow us to make some realistic prediction of the nuclear symmetry energy and its density dependence. Moreover, given the neutron skin of the target related directly to the neutron-proton difference of the ground-state density, it can be well probed in the analysis of the charge-exchange (3He,t) reactions at medium energies when the two-step processes can be neglected and the t-matrix interaction can be used in the folding calculation.

  4. Charge exchange in fluid description of partially ionized plasmas

    NASA Astrophysics Data System (ADS)

    Vranjes, J.; Kono, M.; Luna, M.

    2016-02-01

    The effects of charge exchange on waves propagating in weakly ionized plasmas are discussed. It is shown that for low-frequency processes, ions and neutrals should be treated as a single fluid with some effective charge on all of them. We have derived a new momentum equation which should be used in such an environment. As a result, the low-frequency magnetic waves can propagate even if particles are not magnetized, which is entirely due to the charge exchange and the fact that it is not possible to separate particles into two different populations as charged and neutral species. So there can be no friction force between ions and neutrals in the usual sense. The mean force per particle is proportional to the ionization ratio ni/(ni + nn). Regarding the application of the theory to the Alfvén wave propagation in the lower solar atmosphere, the results predict that the plane of displacement of the fluid must change by 90 deg when an Alfvén wave propagates from the area where particles are un-magnetized (photosphere) to the area where they are magnetized (chromosphere). Because of the most accurate cross-sections which we have here, it is possible to very accurately determine altitudes at which such rotation of the Alfvén wave takes place.

  5. Apparent elastic modulus and hysteresis of skeletal muscle cells throughout differentiation

    NASA Technical Reports Server (NTRS)

    Collinsworth, Amy M.; Zhang, Sarah; Kraus, William E.; Truskey, George A.

    2002-01-01

    The effect of differentiation on the transverse mechanical properties of mammalian myocytes was determined by using atomic force microscopy. The apparent elastic modulus increased from 11.5 +/- 1.3 kPa for undifferentiated myoblasts to 45.3 +/- 4.0 kPa after 8 days of differentiation (P < 0.05). The relative contribution of viscosity, as determined from the normalized hysteresis area, ranged from 0.13 +/- 0.02 to 0.21 +/- 0.03 and did not change throughout differentiation. Myosin expression correlated with the apparent elastic modulus, but neither myosin nor beta-tubulin were associated with hysteresis. Microtubules did not affect mechanical properties because treatment with colchicine did not alter the apparent elastic modulus or hysteresis. Treatment with cytochalasin D or 2,3-butanedione 2-monoxime led to a significant reduction in the apparent elastic modulus but no change in hysteresis. In summary, skeletal muscle cells exhibited viscoelastic behavior that changed during differentiation, yielding an increase in the transverse elastic modulus. Major contributors to changes in the transverse elastic modulus during differentiation were actin and myosin.

  6. Kinetic theory for charge-exchange spectroscopy: Effects of magnetic and electric fields on the distribution function after charge-exchange

    SciTech Connect

    Burrell, K. H.; Munoz Burgos, J. M.

    2012-07-15

    In plasmas equipped with neutral beam injection, excitation of atomic spectral lines via charge-exchange with neutral atoms is the basis of one of the standard plasma diagnostic techniques for ion density, temperature, and velocity. In order to properly interpret the spectroscopic results, one must consider the effects of the energy dependence of the charge-exchange cross-section as well as the motion of the ion after charge-exchange during the period when it is still in the excited state. This motion is affected by the electric and magnetic fields in the plasma. The present paper gives results for the velocity distribution function of the excited state ions and considers in detail the cross-section and ion motion effects on the post charge-exchange velocity. The expression for this velocity in terms of the charge-exchange cross-section and the pre charge-exchange velocity allows that latter velocity to be determined. The present paper is the first to consider the effect of the electric as well as the magnetic field and demonstrates that electric field and diamagnetic terms appear in the expression for the inferred velocity. The present formulation also leads to a novel technique for assessing the effect of the energy dependence of the charge-exchange cross-section on the inferred ion temperature.

  7. Charge-exchange reactions with a radioactive triton beam

    SciTech Connect

    Jaenecke, J.

    1998-12-21

    A high-resolution (t, {sup 3}He) test experiment has been performed recently by making use of a secondary triton beam produced by fragmentation of {alpha}-particles. The purpose of this charge-exchange experiment was to achieve good energy resolution in an (n,p)-type reaction at intermediate bombarding energies. The experiment was carried out with the K1200 cyclotron at the National Superconducting Cyclotron Laboratory using the A1200 beam-analysis system and the S800 magnetic spectrometer. The beam-analysis system was used to transport the energy-dispersed radioactive triton beam from the production target to the target position, and the magnetic spectrometer was used to focus the dispersion-matched {sup 3}He particles from the (t, {sup 3}He) reaction at 0 degree sign onto the focal plane of the spectrometer. An energy resolution of 200-250 keV was achieved.

  8. Improved edge charge exchange recombination spectroscopy in DIII-D

    NASA Astrophysics Data System (ADS)

    Chrystal, C.; Burrell, K. H.; Grierson, B. A.; Haskey, S. R.; Groebner, R. J.; Kaplan, D. H.; Briesemeister, A.

    2016-11-01

    The charge exchange recombination spectroscopy diagnostic on the DIII-D tokamak has been upgraded with the addition of more high radial resolution view chords near the edge of the plasma (r/a > 0.8). The additional views are diagnosed with the same number of spectrometers by placing fiber optics side-by-side at the spectrometer entrance with a precise separation that avoids wavelength shifted crosstalk without the use of bandpass filters. The new views improve measurement of edge impurity parameters in steep gradient, H-mode plasmas with many different shapes. The number of edge view chords with 8 mm radial separation has increased from 16 to 38. New fused silica fibers have improved light throughput and clarify the observation of non-Gaussian spectra that suggest the ion distribution function can be non-Maxwellian in low collisionality plasmas.

  9. Pion double charge exchange in a composite-meson model

    SciTech Connect

    Kezerashvili, R. Ya.; Boyko, V. S.

    2007-01-15

    The pion double charge exchange amplitude is evaluated in a composite-meson model based on the four-quark interaction. The model assumes that the mesons are two-quark systems and can interact with each other only through quark loops. To evaluate the meson exchange current contribution, the form factors of the two-pion decay modes of the {rho},{sigma}, and f{sub 0} mesons have been used in the calculations. The contribution of the four-quark box diagram has been taken into account as well as a contact diagram. The contributions of the {rho},{sigma}, and f{sub 0} mesons increase the forward scattering cross section, which depends weakly on the energy.

  10. Improved edge charge exchange recombination spectroscopy in DIII-D

    DOE PAGESBeta

    Chrystal, Colin; Burrell, K. H.; Grierson, Brian A.; Haskey, Shaun R.; Groebner, R. J.; Kaplan, David H.; Briesemeister, Alexis R.

    2016-08-02

    The charge exchange recombination spectroscopy diagnostic on the DIII-D tokamak has been upgraded with the addition of more high radial resolution view chords near the edge of the plasma (r/a > 0.8). The additional views are diagnosed with the same number of spectrometers by placing fiber optics side-by-side at the spectrometer entrance with a precise separation that avoids wavelength shifted crosstalk without the use of bandpass filters. The new views improve measurement of edge impurity parameters in steep gradient, H-mode plasmas with many different shapes. The number of edge view chords with 8 mm radial separation has increased from 16more » to 38.As a result, new fused silica fibers have improved light throughput and clarify the observation of non-Gaussian spectra that suggest the ion distribution function can be non-Maxwellian in low collisionality plasmas.« less

  11. Extraction of Poloidal Velocity from Charge Exchange Recombination Spectroscopy Measurements

    SciTech Connect

    W.M. Solomon; K.H. Burrell; P. Gohil; R.J. Groebner; L.R. Baylor

    2004-07-16

    A novel approach has been implemented on DIII-D to allow the correct determination of the plasma poloidal velocity from charge exchange spectroscopy measurements. Unlike usual techniques, the need for detailed atomic physics calculations to properly interpret the results is alleviated. Instead, the needed atomic physics corrections are self-consistently determined directly from the measurements, by making use of specially chosen viewing chords. Modeling results are presented that were used to determine a set of views capable of measuring the correction terms. We present the analysis of a quiescent H-mode discharge, illustrating that significant modifications to the velocity profiles are required in these high ion temperature conditions. We also present preliminary measurements providing the first direct comparison of the standard cross-section correction to the atomic physics calculations.

  12. Charge exchange of a polar molecule at its cation

    SciTech Connect

    Buslov, E. Yu. Zon, B. A.

    2011-01-15

    The Landau-Herring method is used to derive an analytic expression for the one-electron exchange interaction of a polar molecule with its positively charged ion, induced by a {sigma}-electron. Analogously to the classical Van der Pole method, the exchange interaction potential is averaged over the rotational states of colliding particles. The resonant charge-transfer cross section is calculated, and the effect of the dipole moments of the core on the cross section is analyzed. It is shown that allowance for the dependence of the exchange potential on the orientation of the dipole moments relative to the molecular axis may change the dependence of the cross section on the velocity of colliding particles, which is typical of the resonant charge exchange, from the resonance to the quasi-resonance dependence.

  13. Influence of charge exchange on the collection of the laser produced ions

    NASA Astrophysics Data System (ADS)

    Hasegawa, Shuichi; Takei, Manabu; Suzuki, Atsuyuki; Kurosawa, Hitoshi

    2001-12-01

    We evaluated influences of charge exchange on ion collection of laser isotope separation of uranium. We made a two-dimensional code based on fluid dynamics taking the charge exchange term into consideration. Parametric study was performed in terms of electric amplitude, ion density, and electron temperature. In addition to parallel electrode arrangement, calculations were performed for Π- and M-type arrangements. The ratio of charge exchanged ions is found to largely depend on the collection time.

  14. Absolute elastic differential electron scattering cross sections in the intermediate energy region. IV - CO

    NASA Technical Reports Server (NTRS)

    Tanaka, H.; Srivastava, S. K.; Chutjian, A.

    1978-01-01

    Using a crossed electron beam-molecular beam scattering geometry and a relative-flow technique, ratios of elastic differential cross sections of CO to those of He have been measured at electron impact energies of 3, 5, 7.5, 9.9, 15, 20, 30, 50, 75, and 100 eV. At each energy, an angular range of 15 to 130 deg has been covered. These ratios have been multiplied by previously known He elastic differential cross sections to obtain elastic differential cross sections for CO. Since pure rotational excitations were not resolved, the elastic differential cross sections are a sum of elastic and pure rotational excitations at room temperature. From a knowledge of differential cross sections (DCS), integral and momentum transfer cross sections have been calculated. Both the DCS and integral cross sections are compared at 50, 75, and 100 eV to a recent two-potential theory of e-molecule scattering. Present results show that the isoelectronic molecules CO and N2 have very similar magnitudes and shapes of their differential cross sections.

  15. Tangential differential calculus and the finite element modeling of a large deformation elastic membrane problem

    NASA Astrophysics Data System (ADS)

    Hansbo, Peter; Larson, Mats G.; Larsson, Fredrik

    2015-07-01

    We develop a finite element method for a large deformation membrane elasticity problem on meshed curved surfaces using a tangential differential calculus approach that avoids the use of classical differential geometric methods. The method is also applied to form finding problems.

  16. Charge-exchange reactions from the standpoint of the parton model

    NASA Astrophysics Data System (ADS)

    Nekrasov, M. L.

    2015-11-01

    Using simple arguments, we show that charge-exchange reactions at high energies go through the hard scattering of fast quarks. On this basis we describe π-p→ M0n and K-p→ M0Λ, M0=π0,η,η', in a combined approach which defines hard contributions in the parton model and soft ones in Regge phenomenology. The disappearance of a dip according to recent GAMS- 4π data in the differential cross-section K-p→ηΛ at \\vert t\\vert≈ 0.4-0.5 (GeV/c)2 at transition to relatively high momenta, is explained as a manifestation of a mode change of summation of hard contributions from coherent to incoherent. Other manifestations of the mentioned mode change are discussed. Constraints on the η- η{^' mixing and gluonium admixture in η{^' are obtained.

  17. Delta excitations and shell-model information in heavy-ion, charge-exchange reactions

    NASA Technical Reports Server (NTRS)

    Deutchman, P. A.; Maung, K. M.; Norbury, J. W.; Rasmussen, J. O.; Townsend, L. W.

    1986-01-01

    We calculate total cross sections for coherent pion production using localized plane-wave approximations for the shell-structure of valence nucleons that are excited to delta particles in the intermediate state in the (12C, 12B) and (12C, 12N) charge-exchange, heavy-ion reactions. We find comparable agreement to projectile downshift data for 12C(12C, 12B)12N. Then we improve the formalism by replacing the localized plane wave bound states with harmonic oscillator states which are imbedded in a multipole expansion approach and calculate pion differential cross sections to test for the sensitivity of the spectra to the single-particle mass parameter.

  18. Differential stress effect on the structural and elastic properties of forsterite by first-principles simulation

    NASA Astrophysics Data System (ADS)

    Liu, Lei; Du, Jianguo; Liu, Hong; Yi, Li

    2014-08-01

    To understand the effect of differential stress on the properties of forsterite, changes of its structural parameters and elastic properties under different differential stress were calculated by first-principles simulations. Totally, 5 sets of different stresses results (namely x = 0, ±1 and ±2 GPa, x is the stress difference among σzz, σyy or σxx), were calculated. The effect of differential stresses on lattice constants show Poisson effect. Compared with the results under hydrostatic stress, all lattice strain (εa, εb, and εc) significantly increased at differential stress conditions. Furthermore, when the largest differential stresses are positive they more effect on lattice strain than the differential stresses are negative. Effect of different differential stress on density of forsterite is different. Compared with the density under hydrostatic pressure, positive differential stresses applied in the x direction or negative differential stresses applied in the y direction make forsterite density decreasing; however, positive differential stresses applied in the y direction or negative differential stresses applied in the x direction make forsterite density increasing. The density differences caused by differential stress are close to the upper mantle density anomaly. The effect of differential stress on density and lattice parameters is more notable when the absolutely value of Δσxx or Δσyy are the biggest among the differential stresses, namely stresses distributing along a and b axis orientation are more influenced on forsterite structural parameters than c axis orientation. Full elastic constants, bulk and shear modulus of forsterite (C11, C22, C33, C44, C55, C66, C12, C13, C23) were calculated under different stress conditions. Bulk modulus, shear modulus and elastic constants of differential stress are also different with the values at hydrostatic pressure, but the calculated results do not show any significant trends.

  19. XMM-Newton Observations of Solar Wind Charge Exchange Emission

    NASA Technical Reports Server (NTRS)

    Snowden, S. L.; Collier, M. R.; Kuntz, K. D.

    2004-01-01

    We present an XMM-Newton spectrum of diffuse X-ray emission from within the solar system. The spectrum is dominated by O VII and O VIII lines at 0.57 keV and 0.65 keV, O VIII (and possibly Fe XVII) lines at approximately 0.8 keV, Ne IX lines at approximately 0.92 keV, and Mg XI lines at approximately 1.35 keV. This spectrum is consistent with what is expected from charge exchange emission between the highly ionized solar wind and either interstellar neutrals in the heliosphere or material from Earth's exosphere. The emission is clearly seen as a low-energy ( E less than 1.5 keV) spectral enhancement in one of a series of observations of the Hubble Deep Field North. The X-ray enhancement is concurrent with an enhancement in the solar wind measured by the ACE satellite. The solar wind enhancement reaches a flux level an order of magnitude more intense than typical fluxes at 1 AU, and has ion ratios with significantly enhanced higher ionization states. Whereas observations of the solar wind plasma made at a single point reflect only local conditions which may only be representative of solar wind properties with spatial scales ranging from less than half of an Earth radii (approximately 10 s) to 100 Earth radii, X-ray observations of solar wind charge exchange are remote sensing measurements which may provide observations which are significantly more global in character. Besides being of interest in its own right for studies of the solar system, this emission can have significant consequences for observations of more cosmological objects. It can provide emission lines at zero redshift which are of particular interest (e.g., O VII and O VIII) in studies of diffuse thermal emission, and which can therefore act as contamination in objects which cover the entire detector field of view. We propose the use of solar wind monitoring data, such as from the ACE and Wind spacecraft, as a diagnostic to screen for such possibilities.

  20. Charge-Exchange Processes of Titanium-Doped Aluminate Crystals

    NASA Astrophysics Data System (ADS)

    Wong, Wing Cheong

    1995-01-01

    Titanium exists in more than one charge state in the aluminate crystals: it is stable as Ti^ {3+} and Ti^{4+}. Other than the intense Ti^{4+ } absorption, a ubiquitous absorption/luminescence excitation band in the UV region is identified as a titanium -bound exciton in Al_2rm O_3, Y_3Al_5rm O_{12}, {rm YAlO}_3, MgAl_2O _4, and LaMgAl_{11} {rm O}_{19}. One -step and two-step photoconductivities of Ti^ {3+} are measured and compared. While the selectivity of the two-step process is demonstrated, its use in locating the energy threshold is hampered by the small Franck-Condon factor for the transition between the Ti^{3+} ^2{ rm E} excited state and Ti^ {4+}. The titanium-bound exciton band, together with the one-step photocurrent signal, makes it possible to determine the photoionization energy threshold accurately. The charge-transfer transition energy thresholds of Ti^{4+} are obtained from the emission and the luminescence excitation spectra. Locally and non-locally charge compensated Ti^{4+ } are found in Al_2{rm O}_3. The luminescence kinetics for the two kinds of Ti^{4+} are well explained by a three-level system with a lower triplet excited state and a higher singlet excited state. These charge-exchange threshold energies can be deduced from the Born-Haber thermodynamical cycle. The electrostatic site potentials are calculated and from it, the calculated photoionization and charge-transfer energy thresholds are found to be consistent with the experimental results. The deficiency of this model is pointed out and possible improvement is discussed. Quantitatively, the sum of the two charge-exchange energy thresholds is close to the band-gap energy of the host crystal. This offers a convenient way for material characterization. Provided that any two of the three quantities (band-gap energy, photoionization energy threshold, and charge-transfer transition energy threshold) have been found, the third quantity can be calculated. In addition, the trapping of charge

  1. Charge exchange of solar wind ions in the Comet Halley coma

    NASA Technical Reports Server (NTRS)

    Shelley, E. G.; Ing-H. afgoldstein, B. E. AGGOLDSTEIN, R.; Ing-H. afgoldstein, B. E. AGGOLDSTEIN, R.

    1986-01-01

    The He(2+) and He(+) radial profiles measured by the Giotto mass spectrometer on the inbound trajectory to comet Halley are compared to a simple 1-dimensional charge exchange model. Results indicate that charge exchange alone cannot account for the observed radial profiles of He(2+) and He(+).

  2. X-ray emission from charge exchange of highly-charged ions in atoms and molecules

    NASA Technical Reports Server (NTRS)

    Greenwood, J. B.; Williams, I. D.; Smith, S. J.; Chutjian, A.

    2000-01-01

    Charge exchange followed by radiative stabilization are the main processes responsible for the recent observations of X-ray emission from comets in their approach to the Sun. A new apparatus was constructed to measure, in collisions of HCIs with atoms and molecules, (a) absolute cross sections for single and multiple charge exchange, and (b) normalized X-ray emission cross sections.

  3. Spin-Isospin responses via charge exchange reactions of RI beams at SHARAQ

    SciTech Connect

    Shimoura, Susumu

    2012-11-12

    Nuclear spectroscopy via direct reactions of RI beams is discussed focusing on characteristics of charge-exchange reactions of RI beams. Recent experiments using the SHARAQ spectrometer at the RIBF are presented, where isovector spin monopole and spin-non-flip monopole responses are studied by charge exchange reaction of RI beams. Some experimental plans and perspectives are also presented.

  4. Characteristics of solid-target charge-exchange analyzers for energetic ion diagnostics on tokamaks

    SciTech Connect

    Beiersdorfer, P.; Roquemore, A.L.; Kaita, R.

    1987-05-01

    Compact electrostatic charge-exchange analyzers have been constructed for installation in areas of high magnetic fields and restricted access near tokamak fusion devices. The analyzers employed carbon stripping foils, and have been calibrated for proton energies between 1 and 70 keV. They have been successfully used to study charge-exchange losses in auxiliary-heated tokamak plasmas.

  5. Extracting forward strong amplitudes from elastic differential cross sections

    SciTech Connect

    C.M. Chen; D.J. Ernst; Mikkel B. Johnson

    2001-07-01

    The feasibility of a model-independent extraction of the forward strong amplitude from elastic nuclear cross section data in the Coulomb-nuclear interference region is assessed for {pi} and K{sup +} scattering at intermediate energies. Theoretically-generated ''data'' are analyzed to provide criteria for optimally designing experiments to measure these amplitudes, whose energy dependence (particularly that of the real parts) is needed for disentangling various sources of medium modifications of the projectile-nucleon interaction. The issues considered include determining the angular region over which to make the measurements, the role of the most forward angles measured, and the effects of statistical and systematic errors. We find that there is a region near the forward direction where Coulomb-nuclear interference allows reliable extraction of the strong forward amplitude for both pions and the K{sup +} from .3 to 1 GeV/c.

  6. Charge Exchange, from the Laboratory to Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Betancourt-Martinez, Gabriele; Beiersdorfer, Peter; Brown, Gregory; Hell, Natalie; Leutenegger, Maurice A.; Porter, Frederick S.; Reynolds, Christopher S.

    2016-04-01

    X-ray emission due to charge exchange (CX) between solar wind ions and neutrals in comets and planetary atmospheres is ubiquitous in the solar system, and is also a significant foreground in all observations from low-Earth orbit. It is also possible that CX is common astrophysically, in any environment where hot plasma and cold gas interact. A current challenge is that theoretical models of CX spectra do not always accurately describe observations, and require further experimental verification. This is especially important to focus on now, as the recent launch of Astro-H is providing us with the first high-resolution spectra of extended x-ray sources. In order to improve our understanding and modeling of CX spectra, we take advantage of the laboratory astrophysics program at the Lawrence Livermore National Laboratory and use an Electron Beam Ion Trap (EBIT) to perform CX experiments, using the EBIT Calorimeter Spectrometer. We present experimental benchmarks that can be used to develop a more comprehensive and accurate CX theory. On the observational side, we also investigate the possibility of CX occurring in the filaments around the central galaxy of the Perseus cluster, NGC 1275. We use Chandra ACIS data, combined with what we know about laboratory CX spectra, to investigate the possibility of CX being a significant contributor to the x-ray emission.

  7. Instability of the heliopause driven by charge exchange interactions

    SciTech Connect

    Avinash, K.; Zank, G. P.; Dasgupta, B.; Bhadoria, Shikha

    2014-08-20

    The stability of the heliopause that separates the tenuous hot magnetized heliosheath plasma from the dense cool local interstellar magnetized plasma is examined using a fully general model that includes all the essential physical processes. Charge exchange coupling between plasma protons and primary interstellar neutral atoms provides an effective gravity that drives Rayleigh-Taylor (RT)-like instabilities. The velocity difference or shear between the heliosheath and interstellar flows, when coupled to energetic neutral atoms (ENAs), drives a Kelvin-Helmholtz (KH)-like instability on the heliopause. The shoulder region of the heliopause is unstable to a new instability that has characteristics of a mixed RT-KH-like mode. The instabilities are not stabilized by typical values of the magnetic fields in the inner and outer heliosheath (OHS). ENAs play an essential role in driving the KH-like instability, which is fully stabilized in their absence by magnetic fields. The nonlinear phase of these instabilities is briefly discussed. We also discuss the possibility that RT-like or mixed KH-RT-like instabilities drag outer heliosheath/very local interstellar medium (OHS/VLISM) magnetic field lines into the inner heliosheath (IHS) with the VLISM flow, and the possibility that IHS and VLISM magnetic field lines experience reconnection. Such reconnection may (1) greatly enhance the mixing of plasmas across the heliopause and (2) provide open magnetic field lines that allow easy ingress of galactic cosmic rays into the heliosphere and corresponding easy loss of anomalous cosmic rays from the heliosphere.

  8. High-throughput charge exchange recombination spectroscopy system on MAST

    SciTech Connect

    Conway, N. J.; Carolan, P. G.; McCone, J.; Walsh, M. J.; Wisse, M.

    2006-10-15

    A major upgrade to the charge exchange recombination spectroscopy system on MAST has recently been implemented. The new system consists of a high-throughput spectrometer coupled to a total of 224 spatial channels, including toroidal and poloidal views of both neutral heating beams on MAST. Radial resolution is {approx}1 cm, comparable to the ion Larmor radius. The toroidal views are configured with 64 channels per beam, while the poloidal views have 32 channels per beam. Background channels for both poloidal and toroidal views are also provided. A large transmission grating is at the heart of the new spectrometer, with high quality single lens reflex lenses providing excellent imaging performance and permitting the full exploitation of the available etendue of the camera sensor. The charge-coupled device camera chosen has four-tap readout at a maximum aggregate speed of 8.8 MHz, and it is capable of reading out the full set of 224 channels in less than 4 ms. The system normally operates at 529 nm, viewing the C{sup 5+} emission line, but can operate at any wavelength in the range of 400-700 nm. Results from operating the system on MAST are shown, including impurity ion temperature and velocity profiles. The system's excellent spatial resolution is ideal for the study of transport barrier phenomena on MAST, an activity which has already been advanced significantly by data from the new diagnostic.

  9. Charge exchange spectroscopy as a fast ion diagnostic on TEXTORa)

    NASA Astrophysics Data System (ADS)

    Delabie, E.; Jaspers, R. J. E.; von Hellermann, M. G.; Nielsen, S. K.; Marchuk, O.

    2008-10-01

    An upgraded charge exchange spectroscopy diagnostic has been taken into operation at the TEXTOR tokamak. The angles of the viewing lines with the toroidal magnetic field are close to the pitch angles at birth of fast ions injected by one of the neutral beam injectors. Using another neutral beam for active spectroscopy, injected counter the direction in which fast ions injected by the first beam are circulating, we can simultaneously measure a fast ion tail on the blue wing of the Dα spectrum while the beam emission spectrum is Doppler shifted to the red wing. An analysis combining the two parts of the spectrum offers possibilities to improve the accuracy of the absolute (fast) ion density profiles. Fast beam modulation or passive viewing lines cannot be used for background subtraction on this diagnostic setup and therefore the background has to be modeled and fitted to the data together with a spectral model for the slowing down feature. The analysis of the fast ion Dα spectrum obtained with the new diagnostic is discussed.

  10. Charge exchange recombination spectroscopy on the T-10 tokamak.

    PubMed

    Klyuchnikov, L A; Krupin, V A; Nurgaliev, M R; Korobov, K V; Nemets, A R; Dnestrovskij, A Yu; Tugarinov, S N; Serov, S V; Naumenko, N N

    2016-05-01

    The charge exchange recombination spectroscopy (CXRS) diagnostics on the T-10 tokamak is described. The system is based on a diagnostic neutral beam and includes three high etendue spectrometers designed for the ITER edge CXRS system. A combined two-channel spectrometer is developed for simultaneous measurements of two beam-induced spectral lines using the same lines of sight. A basic element of the combined spectrometer is a transmitting holographic grating designed for the narrow spectral region 5291 ± 100 Å. The whole CXRS system provides simultaneous measurements of two CXRS impurity spectra and Hα beam line. Ion temperature measurements are routinely provided using the C(6+) CXRS spectral line 5291 Å. Simultaneous measurements of carbon densities and one more impurity (oxygen, helium, lithium etc.) are carried out. Two light collecting systems with 9 lines of sight in each system are used in the diagnostics. Spatial resolution is up to 2.5 cm and temporal resolution of 1 ms is defined by the diagnostic neutral beam diameter and pulse duration, respectively. Experimental results are shown to demonstrate a wide range of the CXRS diagnostic capabilities on T-10 for investigation of impurity transport processes in tokamak plasma. Developed diagnostics provides necessary experimental data for studying of plasma electric fields, heat and particle transport processes, and for investigation of geodesic acoustic modes.

  11. Invited Parallel Talk: Forward pion-nucleon charge exchange reaction and Regge constraints

    NASA Astrophysics Data System (ADS)

    Huang, Fei; Sibirtsev, A.; Krewald, S.; Hanhart, C.; Haidenbauer, J.; Meißner, U.-G.

    2009-12-01

    We present our recent study of pion-nucleon charge exchange amplitudes above 2 GeV. We analyze the forward pion-nucleon charge exchange reaction data in a Regge model and compare the resulting amplitudes with those from the Karlsruhe-Helsinki and George-Washington-University partial-wave analyses. We explore possible high-energy constraints for theoretical baryon resonance analyses in the energy region above 2 GeV. Our results show that for the pion-nucleon charge exchange reaction, the appropriate energy region for matching meson-nucleon dynamics to diffractive scattering should be around 3 GeV for the helicity flip amplitude.

  12. Carbon charge exchange analysis in the ITER-like wall environment

    SciTech Connect

    Menmuir, S.; Giroud, C.; Hawkes, N. C.; Biewer, T. M.; Coffey, I. H.; Delabie, E.; Sertoli, M.

    2014-11-15

    Charge exchange spectroscopy has long been a key diagnostic tool for fusion plasmas and is well developed in devices with Carbon Plasma-Facing Components. Operation with the ITER-like wall at JET has resulted in changes to the spectrum in the region of the Carbon charge exchange line at 529.06 nm and demonstrates the need to revise the core charge exchange analysis for this line. An investigation has been made of this spectral region in different plasma conditions and the revised description of the spectral lines to be included in the analysis is presented.

  13. Carbon charge exchange analysis in the ITER-like wall environment.

    PubMed

    Menmuir, S; Giroud, C; Biewer, T M; Coffey, I H; Delabie, E; Hawkes, N C; Sertoli, M

    2014-11-01

    Charge exchange spectroscopy has long been a key diagnostic tool for fusion plasmas and is well developed in devices with Carbon Plasma-Facing Components. Operation with the ITER-like wall at JET has resulted in changes to the spectrum in the region of the Carbon charge exchange line at 529.06 nm and demonstrates the need to revise the core charge exchange analysis for this line. An investigation has been made of this spectral region in different plasma conditions and the revised description of the spectral lines to be included in the analysis is presented.

  14. Near resonance charge exchange in ion-atom collisions of lithium isotopes.

    PubMed

    Zhang, Peng; Bodo, Enrico; Dalgarno, Alexander

    2009-12-31

    Collisions of ions and atoms of (6)Li and (7)Li are explored theoretically over a wide range of energy from 10(-14) to 1 eV. Accurate ab initio calculations are carried out of the Born-Oppenheimer potentials and the nonadiabatic couplings that are responsible for the near resonance charge exchange. Scattering studies show that the calculated charge exchange cross section follows Wigner's law for inelastic processes for energies below 10(-10) eV and that the zero temperature rate constant for it is 2.1 x 10(-9) cm(3) s(-1). At collision energies much larger than the isotope shift of the ionization potentials of the atoms, we show that the near resonance charge exchange process is equivalent to the resonance charge exchange with cross sections having a logarithmic dependence on energy. A comparison with the Langevin model at intermediate energies is also presented.

  15. Charge exchange x-ray emission: Astrophysical observations and potential diagnostics

    NASA Astrophysics Data System (ADS)

    Morgan, K.; Andrianarijaona, V.; Draganic, I. N.; Defay, X.; Fogle, M.; Galindo-Uribarri, A.; Guillen, C. I.; Havener, C. C.; Hokin, M.; McCammon, D.; Nader, D. J.; Romano, S. L.; Carcoba, F. Salces; Sauter, P.; Seely, D.; Stancil, P. C.; Vane, C. R.; Vassantachart, A. K.; Wulf, D.

    2013-04-01

    Interest in astrophysical sources of charge exchange X-rays has been growing steadily since the discovery of X-ray emission from the comet Hyakutake with ROSAT in 1996. Since then, charge exchange has been observed between solar wind ions and neutrals in the geocorona and in the atmospheres of Mars and Jupiter. Charge exchange with interstellar neutrals within the heliosphere between solar wind ions and neutral hydrogen and helium from the interstellar medium is now acknowledged as contributing a considerable (although currently unknown) fraction of the soft X-ray background. We make a brief survey of the heliospheric, Galactic, and extragalactic systems in which charge exchange has been observed or is predicted to take place. Experiments measuring velocity dependent cross-section and line ratios for Lyman-series lines and He-like triplets are needed to check current theoretical models of charge exchange emission and aid interpretation of observations. We point out a number of systems that are of astrophysical interest that could be the subject of future laboratory investigations, particularly velocity dependent line ratios of the X-ray emission produced by charge exchange between highly ionized common elements (such as O, C, Ne, and Fe) and atomic hydrogen and helium. To begin to address the need for laboratory data we have measured velocity dependent Ly-series line ratios for C6+ ions interacting with H2, He, and Kr gas targets at Oak Ridge National Laboratory's Ion-Atom Merged-Beams Apparatus.

  16. Analysis of isomeric polycyclic aromatic hydrocarbons by charge-exchange chemical ionization mass spectrometry

    SciTech Connect

    Simonsick, W.J. Jr.; Hites, R.A.

    1984-12-01

    Charge-exchange chemical ionization mass spectrometry (using a 15% mixture of methane in argon) yields abundant M/sup +/, M + H/sup +/, M + C/sub 2/H/sub 5//sup +/ ions of polycyclic aromatic hydrocarbons (PAH). On the basis of the relative intensities of the M + H/sup +/ ion to the M/sup +/ ion, this technique can differentiate, in a predictable manner, isomeric structures of PAH. The operating conditions were evaluated and optimized; the most significant contributions to the variations in the (M + H)/sup +//M/sup +/ ratios are the temperature, pressure, and condition of the ion source. The optimum ion source temperature (250/sup 0/C) and pressure (0.8 torr) are easily controlled and regulated. The variable contamination of the ion source is compensated by an internal standard 1,2,3,5-tetrafluorobenzene. The analyses of Standard Reference Materials 1648 and 1649 (air particulate samples) and a carbon black extract are reported. Triphenylene and chrysene, although not chromatographically resolved, can be quantitated by using this technique. The identification of acephenanthrylene based on the measurement of ratios and calculated ionization potentials is also presented.

  17. Charge-exchange Induced Modulation of the Heliosheath Ion Distribution Downstream of the Termination Shock

    NASA Astrophysics Data System (ADS)

    Fahr, H. J.; Fichtner, H.; Scherer, K.

    2015-12-01

    We consider the evolution of the solar wind ion distribution function alongthe plasma flow downstream from the termination shock induced by chargeexchange processes with cold interstellar H-atoms. We start from a kineticphase space transport equation valid in the bulk frame of the plasma flowthat takes into account convective changes, cooling processes, energydiffusion and ion injection, and describes solar wind and pick-up ionsas a co-moving, isotropic, joint ion population. From this kinetic transportequation one can ascend to an equation for the pressure moment of the iondistribution function, a so-called pressure transport equation, describingthe evolution of the ion pressure in the comoving rest frame. Assuming thatthe local ion distribution can be represented by an adequate kappa functionwith a kappa parameter that varies with the streamline coordinate, weobtain an ordinary differential equation for kappa as function of thestreamline coordinate s. With this result then we gain the heliosheath iondistribution function downstream of the termination shock. The latter thencan be used to predict the Voyager-2 measured moments of the distributionfunction like ion density and ion temperature, and it can also be used topredict spectral fluxes of ENA`s originating from these ions and registeredby IBEX-Hi and IBEX-Lo.We especially analyse the solar wind ion temperature decreasemeasured by Voyager-2 between the years 2008 to 2011 and try to explain itas a charge-exchange induced cooling of the ion distribution function duringthe associated ion convection period.

  18. Neutrino and antineutrino charge-exchange reactions on {sup 12}C

    SciTech Connect

    Samana, A. R.; Krmpotic, F.; Paar, N.; Bertulani, C. A.

    2011-02-15

    We extend the formalism of weak interaction processes, obtaining new expressions for the transition rates, which greatly facilitate numerical calculations, for both neutrino-nucleus reactions and muon capture. Explicit violation of the conserved vector current hypothesis by the Coulomb field, as well as development of a sum-rule approach for inclusive cross sections, has been worked out. We have done a thorough study of exclusive (ground-state) properties of {sup 12}B and {sup 12}N within the projected quasiparticle random phase approximation (PQRPA). Good agreement with experimental data achieved in this way put into evidence the limitations of the standard RPA and QRPA models, which come from the inability of the RPA to open the p{sub 3/2} shell and from the nonconservation of the number of particles in the QRPA. The inclusive neutrino/antineutrino ({nu}/{nu}-tilde) reactions {sup 12}C({nu},e{sup -}){sup 12}N and {sup 12}C({nu}-tilde,e{sup +}){sup 12}B are calculated within both the PQRPA and the relativistic QRPA. It is found that (i) the magnitudes of the resulting cross sections are close to the sum-rule limit at low energy, but significantly smaller than this limit at high energies, for both {nu} and {nu}-tilde; (ii) they increase steadily when the size of the configuration space is augmented, particularly for {nu}/{nu}-tilde energies >200 MeV; and (iii) they converge for sufficiently large configuration space and final-state spin. The quasi-elastic {sup 12}C({nu},{mu}{sup -}){sup 12}N cross section recently measured in the MiniBooNE experiment is briefly discussed. We study the decomposition of the inclusive cross section based on the degree of forbiddenness of different multipoles. A few words are dedicated to the {nu}/{nu}-tilde-{sup 12}C charge-exchange reactions related to astrophysical applications.

  19. Laminin and biomimetic extracellular elasticity enhance functional differentiation in mammary epithelia

    SciTech Connect

    Alcaraz, Jordi; Xu, Ren; Mori, Hidetoshi; Nelson, Celeste M.; Mroue, Rana; Spencer, Virginia A.; Brownfield, Doug; Radisky, Derek C.; Bustamante, Carlos; Bissell, Mina J.

    2008-10-20

    In the mammary gland, epithelial cells are embedded in a 'soft' environment and become functionally differentiated in culture when exposed to a laminin-rich extracellular matrix gel. Here, we define the processes by which mammary epithelial cells integrate biochemical and mechanical extracellular cues to maintain their differentiated phenotype. We used single cells cultured on top of gels in conditions permissive for {beta}-casein expression using atomic force microscopy to measure the elasticity of the cells and their underlying substrata. We found that maintenance of {beta}-casein expression required both laminin signalling and a 'soft' extracellular matrix, as is the case in normal tissues in vivo, and biomimetic intracellular elasticity, as is the case in primary mammary epithelial organoids. Conversely, two hallmarks of breast cancer development, stiffening of the extracellular matrix and loss of laminin signalling, led to the loss of {beta}-casein expression and non-biomimetic intracellular elasticity. Our data indicate that tissue-specific gene expression is controlled by both the tissues unique biochemical milieu and mechanical properties, processes involved in maintenance of tissue integrity and protection against tumorigenesis.

  20. Differential elastic responses to barrier-altering agonists in two types of human lung endothelium.

    PubMed

    Viswanathan, P; Ephstein, Y; Garcia, J G N; Cho, M; Dudek, S M

    2016-09-16

    Vascular integrity is primarily determined by endothelial cell (EC) cytoskeletal structure that is differentially regulated by various stimuli. In this study, atomic force microscopy (AFM) was used to characterize structural and mechanical properties in the cytoskeleton of cultured human pulmonary artery EC (HPAEC) and human lung microvascular EC (HLMVEC) by determining elastic properties (Young's modulus) in response to endogenous barrier protective agents sphingosine 1-phosphate (S1P) and hepatocyte growth factor (HGF), or the barrier disruptive molecule thrombin. Initial studies in unstimulated cells indicate higher baseline peripheral elastic modulus values in HPAEC (mean 2.9 KPa) than in HLMVEC (1.8 KPa). After 30 min of stimulation, S1P induced the highest Young's modulus increase (6.1 KPa) compared to the other barrier enhancing stimuli, HGF (5.8 KPa) and the pharmaceutical agent and S1P analog FTY720 (4.1 KPa). In contrast, the barrier disruptive agent thrombin decreased values from 2.5 KPa to 0.7 KPa depending on the cell type and treatment time. AFM topographical imaging supports these quantitative biophysical data regarding differential peripheral elastic properties in EC. Overall, these AFM studies provide novel insights into the biomechanical properties of human lung EC that regulate vascular barrier function and have potential applicability to pathophysiologic vascular leak syndromes such as acute lung injury. PMID:27473658

  1. Laminin and biomimetic extracellular elasticity enhance functional differentiation in mammary epithelia

    PubMed Central

    Alcaraz, Jordi; Xu, Ren; Mori, Hidetoshi; Nelson, Celeste M; Mroue, Rana; Spencer, Virginia A; Brownfield, Doug; Radisky, Derek C; Bustamante, Carlos; Bissell, Mina J

    2008-01-01

    In the mammary gland, epithelial cells are embedded in a ‘soft' environment and become functionally differentiated in culture when exposed to a laminin-rich extracellular matrix gel. Here, we define the processes by which mammary epithelial cells integrate biochemical and mechanical extracellular cues to maintain their differentiated phenotype. We used single cells cultured on top of gels in conditions permissive for β-casein expression using atomic force microscopy to measure the elasticity of the cells and their underlying substrata. We found that maintenance of β-casein expression required both laminin signalling and a ‘soft' extracellular matrix, as is the case in normal tissues in vivo, and biomimetic intracellular elasticity, as is the case in primary mammary epithelial organoids. Conversely, two hallmarks of breast cancer development, stiffening of the extracellular matrix and loss of laminin signalling, led to the loss of β-casein expression and non-biomimetic intracellular elasticity. Our data indicate that tissue-specific gene expression is controlled by both the tissues' unique biochemical milieu and mechanical properties, processes involved in maintenance of tissue integrity and protection against tumorigenesis. PMID:18843297

  2. A review of studies on ion thruster beam and charge-exchange plasmas

    NASA Technical Reports Server (NTRS)

    Carruth, M. R., Jr.

    1982-01-01

    Various experimental and analytical studies of the primary beam and charge-exchange plasmas of ion thrusters are reviewed. The history of plasma beam research is recounted, emphasizing experiments on beam neutralization, expansion of the beam, and determination of beam parameters such as electron temperature, plasma density, and plasma potential. The development of modern electron bombardment ion thrusters is treated, detailing experimental results. Studies on charge-exchange plasma are discussed, showing results such as the relationship between neutralizer emission current and plasma beam potential, ion energies as a function of neutralizer bias, charge-exchange ion current collected by an axially moving Faraday cup-RPA for 8-cm and 30-cm ion thrusters, beam density and potential data from a 15-cm ion thruster, and charge-exchange ion flow around a 30-cm thruster. A 20-cm thruster electrical configuration is depicted and facility effects are discussed. Finally, plasma modeling is covered in detail for plasma beam and charge-exchange plasma.

  3. Neutral atomic oxygen beam produced by ion charge exchange for Low Earth Orbital (LEO) simulation

    NASA Technical Reports Server (NTRS)

    Banks, Bruce; Rutledge, Sharon; Brdar, Marko; Olen, Carl; Stidham, Curt

    1987-01-01

    A low energy neutral atomic oxygen beam system was designed and is currently being assembled at the Lewis Research Center. The system utilizes a 15 cm diameter Kaufman ion source to produce positive oxygen ions which are charge exchange neutralized to produce low energy (variable from 5 to 150 eV) oxygen atoms at a flux simulating real time low Earth orbital conditions. An electromagnet is used to direct only the singly charged oxygen ions from the ion source into the charge exchange cell. A retarding potential grid is used to slow down the oxygen ions to desired energies prior to their charge exchange. Cryogenically cooled diatomic oxygen gas in the charge exchange cell is then used to transfer charge to the oxygen ions to produce a neutral atomic oxygen beam. Remaining non-charge exchanged oxygen ions are then swept from the beam by electromagnetic or electrostatic deflection depending upon the desired experiment configuration. The resulting neutral oxygen beam of 5 to 10 cm in diameter impinges upon target materials within a sample holder fixture that can also provide for simultaneous heating and UV exposure during the atomic oxygen bombardment.

  4. Two-stage Rydberg charge exchange: An efficient method for production of antihydrogen

    SciTech Connect

    Hessels, E.A.; Homan, D.M.; Cavagnero, M.J.

    1998-03-01

    An efficient method for production of cold antihydrogen ({bar H}) is proposed. Alkali-metal atoms laser excited to a Rydberg state are charge exchanged with cold trapped positrons, producing Rydberg states of positronium. In a second Rydberg-state charge exchange, the positronium atoms give up their Rydberg positrons to cold trapped antiprotons, producing Rydberg states of {bar H}. These {bar H} atoms soon decay down to the ground state, and, because they are cold, could be trapped in a magnetic trap. The efficiency of the process results from the extremely large cross sections for Rydberg charge exchange. Classical trajectory Monte Carlo calculations indicate an {bar H} instantaneous production rate of 10{sup 6}/s. {copyright} {ital 1998} {ital The American Physical Society}

  5. Ion temperatures in HIP-1 and SUMMA from charge-exchange neutral optical emission spectra

    NASA Technical Reports Server (NTRS)

    Patch, R. W.; Lauver, M. R.

    1976-01-01

    Ion temperatures were obtained from observations of the H sub alpha, D sub alpha, and He 587.6 nm lines emitted from hydrogen, deuterium, and helium plasmas in the SUMMA and HIP-1 mirror devices at Lewis Research Center. Steady state discharges were formed by applying a radially inward dc electric field between cylindrical or annular anodes and hollow cathodes located at the peaks of the mirrors. The ion temperatures were found from the Doppler broadening of the charge-exchange components of spectral lines. A statistical method was developed for obtaining scaling relations of ion temperature as a function of current, voltage, and magnetic flux density. Derivations are given that take into account triangular monochromator slit functions, loss cones, and superimposed charge-exchange processes. In addition, the Doppler broadening was found to be sensitive to the influence of drift on charge-exchange cross section. The effects of finite ion-cyclotron radius, cascading, and delayed emission are reviewed.

  6. The influence of charge exchange on the velocity distribution of hydrogen in the Venus exosphere

    NASA Technical Reports Server (NTRS)

    Hodges, Richard R., Jr.; Tinsley, Brian A.

    1986-01-01

    The simulation of the exosphere of Venus by a Monte Carlo technique has been extended to provide velocity distribution profiles that can be used with radiative transfer simulation to model the Lyman-alpha emission seen by spacecraft. The line profiles show a narrow core due to the exobase thermal source of hydrogen superimposed on the broad profile of hot hydrogen from charge exchange with hot ions in the nighttime ionosphere. Nightside radial profiles show long tails of upward flowing, escaping atoms. There are some downward and lateral superescape signatures, because the charge exchange source extends well above the exobase. At higher altitudes, flattening and even shallow central valleys appear in the transverse profiles. The planetary average escape rate due to charge exchange was found to be 2.8 x 10 to the 7th/sq cm per s, which is several times larger than escape rates for other candidate mechanisms.

  7. Experimental discovery of charge-exchange-caused dips in spectral lines from laser-produced plasmas.

    PubMed

    Leboucher-Dalimier, E; Oks, E; Dufour, E; Sauvan, P; Angelo, P; Schott, R; Poquerusse, A

    2001-12-01

    We report the first experimental observation of charge-exchange-caused dips (also called x dips) in spectral lines of multicharged ions in laser-produced plasmas. Specifically, in the process of a laser irradiation of targets made out of aluminum carbide, we observed two x dips in the Ly(gamma) line of Al XIII perturbed by fully stripped carbon. From the practical point of view, this opens up a way to experimentally produce not-yet-available fundamental data on charge exchange between multicharged ions, virtually inaccessible by other experimental methods. From the theoretical viewpoint, the results are important because the x dips are the only one signature of charge exchange in profiles of spectral lines emitted by plasmas and they are the only one quasimolecular phenomenon that could be observed at relatively "low" densities of laser-produced plasmas. PMID:11736229

  8. Charge exchange in C^6+ + H and C^6+ + H2 collisions

    NASA Astrophysics Data System (ADS)

    Guevara-Leon, Nicolais; Saha, Bidhan; Sabin, John R.; Deumens, Erik; Ohrn, N. Y.

    2010-03-01

    In the solar wind, C^6+ ion is one of the most abundant ionic species and its interaction with comets as well as the atmosphere of planets of the solar system produces several interesting phenomena. The charge exchange reaction is one of the most relevant process as it may provide a possible explanation for the X-ray emission from these objects. Electron capture into a highly excited state of C^5+ ion usually generates radiation in the X-ray region of the spectrum. In the present work, charge exchange in C^6+ + H and C^6+ + H2 collisions are investigated theoretically using electron nuclear dynamics (END) [1] at projectile energies below the ionization threshold. For H2 the one- and two- electron charge exchange cross sections are calculated and compared with other theoretical and experimental data. Orientation effects for the collision with the hydrogen molecules will also be discussed at the conference.

  9. Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization.

    PubMed

    Vaikkinen, Anu; Kauppila, Tiina J; Kostiainen, Risto

    2016-08-01

    The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M(+.) decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques. Graphical Abstract ᅟ.

  10. Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization.

    PubMed

    Vaikkinen, Anu; Kauppila, Tiina J; Kostiainen, Risto

    2016-08-01

    The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M(+.) decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques. Graphical Abstract ᅟ. PMID:27126470

  11. Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization

    NASA Astrophysics Data System (ADS)

    Vaikkinen, Anu; Kauppila, Tiina J.; Kostiainen, Risto

    2016-08-01

    The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M+. decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques.

  12. Laboratory simulation of charge exchange-produced X-ray emission from comets.

    PubMed

    Beiersdorfer, P; Boyce, K R; Brown, G V; Chen, H; Kahn, S M; Kelley, R L; May, M; Olson, R E; Porter, F S; Stahle, C K; Tillotson, W A

    2003-06-01

    In laboratory experiments using the engineering spare microcalorimeter detector from the ASTRO-E satellite mission, we recorded the x-ray emission of highly charged ions of carbon, nitrogen, and oxygen, which simulates charge exchange reactions between heavy ions in the solar wind and neutral gases in cometary comae. The spectra are complex and do not readily match predictions. We developed a charge exchange emission model that successfully reproduces the soft x-ray spectrum of comet Linear C/1999 S4, observed with the Chandra X-ray Observatory.

  13. Simulation of charge exchange plasma propagation near an ion thruster propelled spacecraft

    NASA Technical Reports Server (NTRS)

    Robinson, R. S.; Kaufman, H. R.; Winder, D. R.

    1981-01-01

    A model describing the charge exchange plasma and its propagation is discussed, along with a computer code based on the model. The geometry of an idealized spacecraft having an ion thruster is outlined, with attention given to the assumptions used in modeling the ion beam. Also presented is the distribution function describing charge exchange production. The barometric equation is used in relating the variation in plasma potential to the variation in plasma density. The numerical methods and approximations employed in the calculations are discussed, and comparisons are made between the computer simulation and experimental data. An analytical solution of a simple configuration is also used in verifying the model.

  14. Interaction of a solar array with an ion thruster due to the charge-exchange plasma

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.

    1976-01-01

    The generation of a charge exchange plasma by a thruster, the transport of this plasma to the solar array, and the interaction of the solar array with the plasma after it arrives are all described. The generation of this plasma is described accurately from thruster geometry and operating conditions. The transport of the charge exchange plasma was studied experimentally with a 15 cm thruster. A model was developed for simple thruster array configurations. A variety of experiments were surveyed for the interaction of the plasma at the solar array.

  15. X-ray Signature of Charge Exchange in the Spectra of L-shell Iron Ions

    SciTech Connect

    Beiersdorfer, P; Schweikhard, L; Liebisch, P; Brown, G V

    2007-01-05

    The X-ray signature of charge exchange between highly charged L-shell iron ions and neutral gas atoms was studied in the laboratory in order to assess its diagnostic utility. Significant differences with spectra formed by electron-impact excitation were observed. In particular, a strong enhancement was found of the emission corresponding to n {le} 4 {yields} n = 2 transitions relative to the n = 3 {yields} n = 2 emission. This enhancement was detectable even with relatively low-resolution X-ray instrumentation (E/{Delta}E {approx} 10) and may enable future identification of charge exchange as a line-formation mechanism in astrophysical spectra.

  16. Charge exchange processes involving highly charged ions and targets of interest in astrophysics and fusion plasmas

    NASA Astrophysics Data System (ADS)

    Otranto, S.

    2012-11-01

    Renewed interest in charge exchange processes involving highly charged ions arises because of their crucial role in the planned ITER reactor as well as to recent X-ray observations in the astrophysical context. In this work, the classical trajectory Monte Carlo method (CTMC) is used to calculate state selective single charge exchange n-level cross sections and line emission cross sections pertinent to both fields. These are contrasted to recent laboratory data from KVI for the Xe18+ + Na(3s) collision system and NIST/BERLIN-EBIT data for the Ar18+ +Ar system.

  17. Laboratory simulation of charge exchange-produced X-ray emission from comets.

    PubMed

    Beiersdorfer, P; Boyce, K R; Brown, G V; Chen, H; Kahn, S M; Kelley, R L; May, M; Olson, R E; Porter, F S; Stahle, C K; Tillotson, W A

    2003-06-01

    In laboratory experiments using the engineering spare microcalorimeter detector from the ASTRO-E satellite mission, we recorded the x-ray emission of highly charged ions of carbon, nitrogen, and oxygen, which simulates charge exchange reactions between heavy ions in the solar wind and neutral gases in cometary comae. The spectra are complex and do not readily match predictions. We developed a charge exchange emission model that successfully reproduces the soft x-ray spectrum of comet Linear C/1999 S4, observed with the Chandra X-ray Observatory. PMID:12791989

  18. Excitation and Charge Exchange Phenomena in Astronomical Objects: Measurement of Cross Sections and Lifetimes

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara; Smith, S.; Lozano, J.; Cadez, I.; Greewnood, J.; Mawhovter, R.; Williams, I.; Niimura, M.

    2003-01-01

    This document addresses extreme ultraviolet radiation and X-ray emissions from comets, planets and heliospheric gases focusing on the measurement of charge-exchange cross sections and radiative lifetimes. Highly-charged heavy ions present in the solar wind, and their abundance relative to the total oxygen-ion abundance are detailed. The plan for the Jet Propulsion Laboratory high-charge ion facility is outlined detailing its ability to measure absolute collisional excitation cross sections, absolute charge-exchange cross sections, lifetimes of metastable ion levels, and X-ray emission spectra following charge changes.

  19. Intermediate ionization continua for double charge exchange at high impact energies

    NASA Astrophysics Data System (ADS)

    Belkić, D.ževad

    1993-05-01

    We investigate the problem of two-electron capture from heliumlike atomic systems by bare nuclei ZP+(ZTe1,e2)i-->(ZPe1,e2)f+ZT at high incident energies, using the four-body formalism of the first- and second-order theories. Our goal is to establish the relative importance of the intermediate ionization continua of the two electrons in comparison with the usual direct path of the double electron transfer. For this purpose we presently introduce the boundary-corrected continuum-intermediate-state (BCIS) approximation, which preserves all the features of two-electron capture as a genuine four-body problem. The proposed second-order theory provides a fully adequate description of the fact that, in an intermediate stage of collision, both electrons move in the field of the two Coulomb centers. The previously devised boundary-corrected first Born (CB1) approximation can be obtained as a further simplification of the BCIS model if the invoked two-electron Coulomb waves are replaced by their long-range logarithmic phase factors defined in terms of the corresponding interaggregate separation R. The BCIS method is implemented on the symmetric resonant double charge exchange in collisions between α particles and He(1s2) at impact energies E>=900 keV. The obtained results for the differential and total cross sections are compared with the available experimental data and satisfactory agreement is recorded. As the incident energy increases, a dramatic improvement is obtained in going from the CB1 to the BCIS approximation, since the latter closely follows the measurement, whereas the former overestimates the observed total cross sections by two orders of magnitude.

  20. Signature of X-ray Line Formation of Fe XVII by Charge Exchange

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, Peter

    Fe XVII dominates the spectral emission of a large number of astrophysical X-ray sources and, thus, is of prime diagnostic importance, as illustrated in numerous measurements by Chandra and XMM-Newton. Although immense progress has been made in laboratory measurements and spectral calculations of collisional plasmas since the launch of these X-ray observatories, model calculations of the Fe XVII X-ray spectrum still do not yield agreement with laboratory measurements or astrophysical observations that is completely satisfactory. Charge exchange is another line formation mechanism that can produce Fe XVII X-ray emission. However, line formation by charge exchange is ill understood, even in the case of 'simple' K-shell spectra of hydrogenlike or heliumlike ions. Nevertheless, simple spectral markers have been developed that represent proof for the presence of charge exchange even if the details of line formation are not yet fully clear. By contrast, there are essentially no charge exchange measurements and calculations for the much more complex Fe XVII L-shell X-ray spectrum. Whether charge exchange contributes an observable amount to X-ray line formation in astrophysical situations is controversial, as (arguably) no incontrovertible spectral evidence for charge exchange has been presented from sources outside our own solar system. In part, this is due to the fact that charge exchange is a mechanism that requires an extended source to be effective, such as circum-stellar halos or super nova remnants expanding into surrounding space, and so far there have been no measurements of extended sources with high spectral resolution. In addition, laboratory measurements have not yet provided data that could serve as spectral markers for charge exchange in the Fe XVII spectrum or, for that matter, in the other L-shell X-ray emission spectra of iron, i.e., Fe XVIII through Fe XXIV. As a result, it is not yet possible to argue that an observed iron L-shell X-ray spectrum is

  1. Measurement of the absolute differential cross section of proton–proton elastic scattering at small angles

    DOE PAGESBeta

    Mchedlishvili, D.; Chiladze, D.; Dymov, S.; Bagdasarian, Z.; Barsov, S.; Gebel, R.; Gou, B.; Hartmann, M.; Kacharava, A.; Keshelashvili, I.; et al

    2016-02-03

    The differential cross section for proton-proton elastic scattering has been measured at a beam kinetic energy of 1.0 GeV and in 200 MeV steps from 1.6 to 2.8 GeV for centre-of-mass angles in the range from 12°-16° to 25°-30°, depending on the energy. A precision in the overall normalisation of typically 3% was achieved by studying the energy losses of the circulating beam of the COSY storage ring as it passed repeatedly through the windowless hydrogen target of the ANKE magnetic spectrometer. It is shown that the data have a significant impact upon the results of a partial wave analysis.more » Furthermore, after extrapolating the differential cross sections to the forward direction, the results are broadly compatible with the predictions of forward dispersion relations.« less

  2. Nonlocal-integro-differential modeling of vibration of elastically supported nanorods

    NASA Astrophysics Data System (ADS)

    Kiani, Keivan

    2016-09-01

    In the previously established nonlocal continuum-based models, small characteristic length was commonly incorporated into the mass matrix and the driving force vector which is a bit in contradiction with our sense regarding these factors. Herein, a nonlocal-integro-differential version of the constitutive relations is employed for the bulk and the surface layer of the nanorod. By adopting Hamilton's principle, integro-partial differential equations of motion of elastically supported nanorods are established accounting for both nonlocality and surface energy effects. Then, these are solved by an efficient meshless methodology. For fixed-fixed and fixed-free nanorods, modal analysis of the problem is also performed and the explicit expressions of the mass and stiffness matrices are derived. For these special cases, the obtained results by the meshless technique are successfully verified with those of the modal solution. In the newly developed numerical model, the small-scale parameter is only incorporated into the stiffness matrix which gives us a more realistic sense about the nonlocality effect. Subsequently, the roles of the surface energy, small-scale parameter, elastic supports, and kernel function on natural frequencies of the nanostructure are discussed and explained. This work can be considered as a pivotal step towards a more reasonable nonlocal modeling of vibration of nanoscale structures.

  3. Measurement of the Neutrino Neutral-Current Elastic Differential Cross Section

    SciTech Connect

    Aguilar-Arevalo, A.A.; Anderson, C.E.; Bazarko, A.O.; Brice, S.J.; Brown, B.C.; Bugel, L.; Cao, J.; Coney, L.; Conrad, J.M.; Cox, D.C.; Curioni, A.; /Yale U. /Argonne

    2010-07-01

    We report a measurement of the flux-averaged neutral-current elastic differential cross section for neutrinos scattering on mineral oil (CH{sub 2}) as a function of four-momentum transferred squared, Q{sup 2}. It is obtained by measuring the kinematics of recoiling nucleons with kinetic energy greater than 50 MeV which are readily detected in MiniBooNE. This differential cross-section distribution is fit with fixed nucleon form factors apart from an axial mass, M{sub A}, that provides a best fit for M{sub A} = 1.39 {+-} 0.11 GeV. Using the data from the charged-current neutrino interaction sample, a ratio of neutral-current to charged-current quasi-elastic cross sections as a function of Q{sup 2} has been measured. Additionally, single protons with kinetic energies above 350 MeV can be distinguished from neutrons and multiple nucleon events. Using this marker, the strange quark contribution to the neutral-current axial vector form factor at Q{sup 2} = 0, {Delta}s, is found to be {Delta}s = 0.08{+-} 0.26.

  4. Pion-nucleon charge exchange amplitudes above 2 GeV

    NASA Astrophysics Data System (ADS)

    Huang, F.; Sibirtsev, A.; Krewald, S.; Hanhart, C.; Haidenbauer, J.; Meißner, U.-G.

    2009-04-01

    The amplitudes for the pion-nucleon charge exchange reaction of the Karlsruhe-Helsinki and the George-Washington-University partial-wave analyses are compared with those of a Regge-cut model with the aim to explore the possibility to provide high-energy constraints for theoretical baryon resonance analyses in the energy region above 2GeV.

  5. Population inversion calculations using near resonant charge exchange as a pumping mechanism

    NASA Technical Reports Server (NTRS)

    Chubb, D. L.; Rose, J. R.

    1972-01-01

    Near resonance charge exchange between ions of a large ionization potential gas such as helium or neon and vapors of metals such as zinc, cadmium, selenium, or tellurium has produced laser action in the metal ion gas. The possibility of obtaining population inversions in near resonant charge exchange systems (Xe-Ca, Xe-Mg, Xe-Sr, Xe-Ba, Ar-Mg, N-Ca) was investigated. The analysis is an initial value problem that utilizes rate equations for the densities of relevant levels of the laser gas (Ca, Ba, Mg, or Sr) and an electron energy equation. Electron excitation rates are calculated using the Bohr-Thomson approximation for the cross section. Approximations to experimental values of the electron ionization cross section and the ion-atom charge exchange cross section are used. Preliminary results have been obtained for the Ca-Xe system and show that it is possible to obtain gains greater than 10 to the 14th power/m with inversion times up to 8x10 to the minus 7th power second. A possible charge exchange laser system using a MPD arc plasma accelerator is also described.

  6. Short-range NN and N. Delta. correlations in pion double charge exchange (DCX)

    SciTech Connect

    Johnson, M.B.

    1990-01-01

    I will review several important results related to the short-range nucleon-nucleon and delta-nucleon interaction that have been obtained from recent studies of pion double charge exchange in selected nuclei. 32 refs., 5 figs., 3 tabs.

  7. Development of the charge exchange type beam scraper system at the J-PARC

    NASA Astrophysics Data System (ADS)

    Okabe, K.; Yamamoto, K.; Kinsho, M.

    2016-03-01

    Improvement in injection beam quality at the Japan Proton Accelerator Research Complex 3-GeV rapid cycle synchrotron is to mitigate beam loss at the injection section. We developed a charge-exchange type scraper system with a thin carbon foil to collimate the beam halo in the injection beam line of the synchrotron. The key issue to realize the scraper is a reduction of the beam loss induced by the multiple-scattering effect of charge-exchange foil placed at the scraper head. In order to determine the adequate foil thickness, a charge-exchange efficiency of a carbon foil and particle-tracking simulation study of the collimated beam have been performed assuming a realistic halo at the scraper section. Using the results of this study, we chose the thickness of a 520 μg /cm2 as the scraper foils to mitigate radiation dose around the L3BT scraper section. A charge-exchange scraper system that prevents the emission of radioactive fragments of the carbon foil was build. The system was put into operation to prove its effectiveness in eliminating the beam halo. From the result of a preliminary beam experiments, we confirmed that the installed scrapers eliminate a transverse beam tail or halo. After two days of operation with beam collimation, the radiation dose level around the scraper section was a tolerable one for the hands-on maintenance.

  8. Pipkin Award Talk: Rydberg Charge Exchange: A Method for Producing Rydberg Positronium and Antihydrogen Atoms

    NASA Astrophysics Data System (ADS)

    Hessels, E. A.

    2003-05-01

    Antihydrogen production via two-stage charge exchange(E.A.Hessels, D.M. Homan and M.J. Cavagnero, Phys. Rev. A. 57), (1998) 1668. may provide extremely cold antimatter atoms that can be trapped for spectroscopic studies. Positrons(J. Estrada, T. Roach, J.N. Tan, P. Yesley, and G. Gabrielse, Phys. Rev. Lett. 84), (2000) 859. and antiprotons(G. Gabrielse, N. S. Bowden, P. Oxley, A. Speck, C. H. Storry, J. N. Tan, M. Wessels, D. Grozonka, W. Oelert, G. Schepers, T. Sefzick, J. Walz, H. Pittner, T. W. Hansch, E. A. Hessels, Phys. Lett. B 548), (2002) 140-145., both cooled to 4 K and loaded into adjacent wells of a Penning trap, provide the basic components. Laser-excited Rydberg cesium atoms are passed through the cloud of trapped positrons and charge exchange with the positrons to form Rydberg states of positronium. These positronium atoms have been observed and are studied by ionizing them and counting the resulting positrons. State analysis of the positronium is obtained by varying the electric field used to ionize the atoms. Large numbers of positronium atoms are produced and their binding energies are found to be similar to that of the incoming Rydberg cesium atoms. A second charge exchange is proposed, in which the neutral positronium travels a short distance to an adjacent antiproton cloud. The result of this second charge exchange would be antihydrogen atoms. The apparatus to test this second charge exchange has already been constructed and preliminary studies have already been made.

  9. Survivable VON mapping with ambiguity similitude for differentiable maximum shared capacity in elastic optical networks

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Zhu, Xiaoxu; Bai, Wei; Zhao, Yongli; Zhang, Jie; Liu, Zhu; Zhou, Ziguan; Ou, Qinghai

    2016-09-01

    Virtualization is considered to be a promising solution to support various emerging applications. This paper illustrates the problem of virtual mapping from a new perspective, and mainly focuses on survivable mapping of virtual networks and the potential trade-off between spectral resource usage effectiveness and failure resilience level. We design an optimum shared protection mapping (OSPM) scheme in elastic optical networks. A differentiable maximum shared capacity of each frequency slot is defined to more efficiently shared protection resource. In order to satisfy various assessment standards, a metric called ambiguity similitude is defined for the first time to give insight on the optimizing difficulty. Simulation results are presented to compare the outcome of the novel OSPM algorithm with traditional dedicated link protection and maximum shared protection mapping. By synthetic analysis, OSPM outperforms the other two schemes in terms of striking a perfect balance among blocking probability, resources utilization, protective success rate, and spectrum redundancy.

  10. Laboratory Studies of X-ray Spectra Formed by Charge Exchange

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, Peter; Ali, R.; Brown, G. V.; Koutroumpa, D.; Kelley, R. L.; Kilbourne, C.; Leutenegger, M. A.; Porter, F.

    2013-04-01

    Charge exchange between ions and neutral atoms or molecules has been accepted at an important soft producing process in our solar system. By extension, charge exchange may contribute to the X-ray emission of circumstellar material. It may also produce X-ray emission at the boundaries of supernova ejecta and star burst galaxies, or whenever hot plasma collides with neutral matter. X-ray spectra of K-shell and L-shell ions formed by charge exchange have now been studied in a variety of laboratory settings. These experiments have shown several characteristic features of line formation by charge exchange when compared to the X-ray emission produced by electron-impact excitation, e.g., enhancement emission of forbidden lines and of lines from levels with high principal quantum number. They have also shown a dependence on the interaction gas and on the energy of the ion-neutral collision. Moreover, the transfer of multiple electrons is typically preferred, provided the donor molecules or atoms have multiple valence-shell electrons. The laboratory measurements are in qualitative agreement with theory. However, the details of the observed X-ray spectra, especially those recorded with high spectral resolution, can differ substantially from predictions, especially for spectra produced at collision velocities equal to or lower than those found in thermal plasmas or produced with neutral gases other than atomic hydrogen. Puzzling discrepancies can be noted, such as enhanced emission from an upper level with the 'wrong' principal quantum number. Even more puzzling is a recent experiment in which two, co-mixed bare ion species of similar atomic number produce very different Lyman series emission upon charge exchange with a given neutral gas, defying both theoretical predictions and empirical scaling. Laboratory measurements have also shown that some of the characteristic features of charge exchange can be reproduced by radiative electron capture, i.e., by capture of a continuum

  11. Charge exchange contamination of CRIT-II barium CIV experiment. [critical ionization velocity in ionosphere

    NASA Technical Reports Server (NTRS)

    Swenson, G. R.; Mende, S. B.; Meyerott, R. E.; Rairden, R. L.

    1991-01-01

    Experiments have been recently performed which attempted to confirm critical ionization velocity (CIV) ionization by deploying chemicals at high velocity in the ionosphere. Specifically, the CRIT-II rocket performed a barium release in the ionosphere, where observations of Ba(+) resonant emissions following the release are believed to have resulted from the CIV process. Calculations are presented which suggest a significant fraction (if not all) of the Ba(+) observed likely resulted from charge exchange with the thermosphere ions and not through CIV processes. The results presented here are pertinent to other CIV experiments performed in the ionosphere. It is recommended that laboratory measurements should be made of the charge exchange cross section between O(+) and Ba as well as other metal vapors used in CIV experiments.

  12. Influence of resonant charge exchange on the viscosity of partially ionized plasma in a magnetic field

    SciTech Connect

    Zhdanov, V. M. Stepanenko, A. A.

    2013-12-15

    The influence of resonant charge exchange for ion-atom interaction on the viscosity of partially ionized plasma embedded in the magnetic field is investigated. The general system of equations used to derive the viscosity coefficients for an arbitrary plasma component in the 21-moment approximation of Grad’s method is presented. The expressions for the coefficients of total and partial viscosities of a multicomponent partially ionized plasma in the magnetic field are obtained. As an example, the coefficients of the parallel and transverse viscosities for the ionic and neutral components of the partially ionized hydrogen plasma are calculated. It is shown that the account for resonant charge exchange can lead to a substantial change of the parallel and transverse viscosity of the plasma components in the region of low degrees of ionization on the order of 0.1.

  13. ROSAT Observations of Solar Wind Charge Exchange with the Lunar Exosphere

    NASA Technical Reports Server (NTRS)

    Collier, Michael R.; Snowden, S. L.; Benna, M.; Carter, J. A.; Cravens, T. E.; Hills, H. Kent; Hodges, R. R.; Kuntz, K. D.; Porter, F. Scott; Read, A.; Robertson, I. P.; Sembay, S. F.; Sibeck, D. G.; Stubbs, Timothy J.; Travnicek, P.

    2012-01-01

    We analyze the ROSAT PSPC soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the count rate in three wedges, two wedges (one north and one south) 13-32 degrees off (19 degrees wide) the terminator towards the dark side and one wedge 38 degrees wide centered on the anti-solar direction. The radial profiles of both the north and the south wedges show substantial limb brightening that is absent in the 38 degree wide antisolar wedge. An analysis of the count rate increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere. Along with Mars, Venus, and Earth, the Moon represents another solar system body at which solar wind charge exchange has been observed. This technique can be used to explore the solar wind-lunar interaction.

  14. Solar wind/local interstellar medium interaction including charge exchange with neural hydrogen

    NASA Technical Reports Server (NTRS)

    Pauls, H. Louis; Zank, Gary P.

    1995-01-01

    We present results from a hydrodynamic model of the interaction of the solar wind with the local interstellar medium (LISM), self-consistently taking into account the effects of charge exchange between the plasma component and the interstellar neutrals. The simulation is fully time dependent, and is carried out in two or three dimensions, depending on whether the helio-latitudinal dependence of the solar wind speed and number density (both giving rise to three dimensional effects) are included. As a first approximation it is assumed that the neutral component of the flow can be described by a single, isotropic fluid. Clearly, this is not the actual situation, since charge exchange with the supersonic solar wind plasma in the region of the nose results in a 'second' neutral fluid propagating in the opposite direction as that of the LISM neutrals.

  15. Competition between charge exchange and chemical reaction - The D2/+/ + H system

    NASA Technical Reports Server (NTRS)

    Preston, R. K.; Cross, R. J., Jr.

    1973-01-01

    Study of the special features of molecular charge exchange and its competition with chemical reaction in the case of the D2(+) + H system. The trajectory surface hopping (TSH) model proposed by Tully and Preston (1971) is used to study this competition for a number of reactions involving the above system. The diatomics-in-molecules zero-overlap approximation is used to calculate the three adiabatic surfaces - one triplet and two singlet - which are needed to describe this system. One of the significant results of this study is that the chemical reaction and charge exchange are strongly coupled. It is also found that the number of trajectories passing into the chemical regions of the three surfaces depends very strongly on the surface crossings.-

  16. POLARIZATION OF THE CHARGE-EXCHANGE X-RAYS INDUCED IN THE HELIOSPHERE

    SciTech Connect

    Gacesa, M.; Kharchenko, V.; Mueller, H.-R.; Cote, R.

    2011-05-10

    We report results of a theoretical investigation of polarization of the X-ray emissions induced in charge-exchange collisions of fully stripped solar wind (SW) ions C{sup 6+} and O{sup 8+} with the heliospheric hydrogen atoms. The polarization of X-ray emissions has been computed for line-of-sight observations within the ecliptic plane as a function of SW ion velocities, including a range of velocities corresponding to the slow and fast SW, and coronal mass ejections. To determine the variability of polarization of heliospheric X-ray emissions, the polarization has been computed for solar minimum conditions with self-consistent parameters of the SW plasma and heliospheric gas and compared with the polarization calculated for an averaged solar activity. We predict the polarization of charge-exchange X-rays to be between 3% and 8%, depending on the line-of-sight geometry, SW ion velocity, and the selected emission lines.

  17. Charge exchange and ionization in hydrogen atom-fully stripped ion collisions in Debye plasmas

    SciTech Connect

    Zhang, H.; Wang, J. G.; He, B.; Qiu, Y. B.; Janev, R. K.

    2007-05-15

    The processes of charge exchange and ionization in collisions of ground state hydrogen atom with fully stripped ions in a weakly coupled plasma are studied by the classical trajectory Monte Carlo method in the collision energy range 10-900 keV/amu. The interparticle interactions are described by the Debye-Hueckel model with inclusion of dynamical effects associated with the projectile velocity. The microcanonical distribution of initial state electronic coordinates and momenta has been determined by inclusion of plasma screening effects. The cross section dependencies on plasma parameters and ion charge and velocity are investigated. It is shown that plasma effects on charge exchange and ionization cross sections are significant and particularly pronounced at low collision velocities. The results of systematic cross section calculations for different values of Debye screening length (in the range 1-50a{sub 0}) and ion charges (in the range 1-14) are presented.

  18. Modulation of terrestrial ion escape flux composition /by low-altitude acceleration and charge exchange chemistry/

    NASA Technical Reports Server (NTRS)

    Moore, T. E.

    1980-01-01

    Motivated by recent observations of highly variable hot plasma composition in the magnetosphere, control of the ionospheric escape flux composition by low-altitude particle dynamics and ion chemistry has been investigated for an e(-), H(+), O(+) ionosphere. It is found that the fraction of the steady state escape flux which is O(+) can be controlled very sensitively by the occurrence of parallel or transverse ion acceleration at altitudes below the altitude where the neutral oxygen density falls rapidly below the neutral hydrogen density and the ionospheric source of O(+) tends to be rapidly converted by charge exchange to H(+). The acceleration is required both to overcome the gravitational confinement of O(+) and to violate charge exchange equilibrium so that the neutral hydrogen atmosphere appears 'optically' thin to escaping O(+). Constraints are placed on the acceleration processes, and it is shown that O(+) escape is facilitated by observed ionospheric responses to magnetic activity.

  19. Charge-exchange erosion studies of accelerator grids in ion thrusters

    NASA Technical Reports Server (NTRS)

    Peng, Xiaohang; Ruyten, Wilhelmus M.; Keefer, Dennis

    1993-01-01

    A particle simulation model is developed to study the charge-exchange grid erosion in ion thrusters for both ground-based and space-based operations. Because the neutral gas downstream from the accelerator grid is different for space and ground operation conditions, the charge-exchange erosion processes are also different. Based on an assumption of now electric potential hill downstream from the ion thruster, the calculations show that the accelerator grid erosion rate for space-based operating conditions should be significantly less than experimentally observed erosion rates from the ground-based tests conducted at NASA Lewis Research Center (LeRC) and NASA Jet Propulsion Laboratory (JPL). To resolve this erosion issue completely, we believe that it is necessary to accurately measure the entire electric potential field downstream from the thruster.

  20. Charge exchange processes in He+/Cu scattering at low energy

    NASA Astrophysics Data System (ADS)

    Khalal-Kouache, K.; Bruckner, B.; Roth, D.; Goebl, D.; Bauer, P.

    2016-09-01

    In this paper we present results on charge exchange of He+ ions at a polycrystalline Cu surface. Monte Carlo simulations were used to calculate the trajectories of projectiles scattered by an angle Θ = 136 ° . By including Auger neutralization and charge exchange in close collisions, energy spectra of the scattered ions as well as ion fraction values were calculated for primary energies in the range 0.5-5 keV and compared to experimental results. In the simulations, the Auger neutralization rate Γ and the probabilities of resonant neutralization (PRN) and reionization (PRI) are treated as free parameters. Using well accepted values from literature for these quantities very good agreement between simulations and experimental data was achieved.

  1. USING KAPPA FUNCTIONS TO CHARACTERIZE OUTER HELIOSPHERE PROTON DISTRIBUTIONS IN THE PRESENCE OF CHARGE-EXCHANGE

    SciTech Connect

    Zirnstein, E. J.; McComas, D. J. E-mail: dmccomas@swri.edu

    2015-12-10

    Kappa functions have long been used in the analysis and modeling of suprathermal particles in various space plasmas. In situ observations of the supersonic solar wind show its distribution contains a cold ion core and power-law tail, which is well-represented by a kappa function. In situ plasma observations by Voyager, as well as observations of energetic neutral atom (ENA) spectra by the Interstellar Boundary Explorer (IBEX), showed that the compressed and heated inner heliosheath (IHS) plasma beyond the termination shock can also be represented by a kappa function. IBEX exposes the IHS plasma properties through the detection of ENAs generated by charge-exchange in the IHS. However, charge-exchange modifies the plasma as it flows through the IHS, and makes it difficult to ascertain the parent proton distribution. In this paper we investigate the evolution of proton distributions, initially represented by a kappa function, that experience losses due to charge-exchange in the IHS. In the absence of other processes, it is no longer representable by a single kappa function due to the energy-dependent, charge-exchange process. While one can still fit a kappa function to the evolving proton distribution over limited energy ranges, this yields fitting parameters (pseudo-density, pseudo-temperature, pseudo-kappa index) that depend on the energy range of the fit. We discuss the effects of fitting a kappa function to the IHS proton distribution over limited energy ranges, its dependence on the initial proton distribution properties at the termination shock, and implications for understanding the observations.

  2. Using Kappa Functions to Characterize Outer Heliosphere Proton Distributions in the Presence of Charge-exchange

    NASA Astrophysics Data System (ADS)

    Zirnstein, E. J.; McComas, D. J.

    2015-12-01

    Kappa functions have long been used in the analysis and modeling of suprathermal particles in various space plasmas. In situ observations of the supersonic solar wind show its distribution contains a cold ion core and power-law tail, which is well-represented by a kappa function. In situ plasma observations by Voyager, as well as observations of energetic neutral atom (ENA) spectra by the Interstellar Boundary Explorer (IBEX), showed that the compressed and heated inner heliosheath (IHS) plasma beyond the termination shock can also be represented by a kappa function. IBEX exposes the IHS plasma properties through the detection of ENAs generated by charge-exchange in the IHS. However, charge-exchange modifies the plasma as it flows through the IHS, and makes it difficult to ascertain the parent proton distribution. In this paper we investigate the evolution of proton distributions, initially represented by a kappa function, that experience losses due to charge-exchange in the IHS. In the absence of other processes, it is no longer representable by a single kappa function due to the energy-dependent, charge-exchange process. While one can still fit a kappa function to the evolving proton distribution over limited energy ranges, this yields fitting parameters (pseudo-density, pseudo-temperature, pseudo-kappa index) that depend on the energy range of the fit. We discuss the effects of fitting a kappa function to the IHS proton distribution over limited energy ranges, its dependence on the initial proton distribution properties at the termination shock, and implications for understanding the observations.

  3. Energy-loss cross sections for inclusive charge-exchange reactions at intermediate energies

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Townsend, Lawrence W.; Dubey, Rajendra R.

    1993-01-01

    Charge-exchange reactions for scattering to the continuum are considered in a high-energy multiple scattering model. Calculations for (p,n) and (He-3,H-3) reactions are made and compared with experimental results for C-12, O-16, and Al-27 targets. Coherent effects are shown to lead to an important role for inelastic multiple scattering terms when light projectiles are considered.

  4. Measurement of pion double charge exchange on carbon-13, carbon-14, magnesium-26, and iron-56

    SciTech Connect

    Seidl, P.A.

    1985-02-01

    Cross sections for the /sup 13,14/C,/sup 26/Mg,/sup 56/Fe(..pi../sup +/,..pi../sup -/)/sup 13,14/O,/sup 26/Si,/sup 56/Ni reactions were measured with the Energetic Pion Channel and Spectrometer at the Clinton P. Anderson Meson Physics Facility for 120 less than or equal to T/sub ..pi../ less than or equal to 292 MeV and 0 less than or equal to theta less than or equal to 50. The double isobaric analog states (DIAS) are of primary interest. In addition, cross sections for transitions to /sup 14/O(0/sup +/, 5.92 MeV), /sup 14/O(2/sup +/, 7.77 MeV), /sup 56/Ni(gs), /sup 13/O(gs), and /sup 13/O(4.21 MeV) are presented. The /sup 13/O(4.21 MeV) state is postulated to have J/sup ..pi../ = 1/2/sup -/. The data are compared to previously measured double-charge-exchange cross sections on other nuclei, and the systematics of double charge exchange on T greater than or equal to 1 target nuclei leading to the DIAS are studied. Near the ..delta../sub 33/ resonance, cross sections for the DIAS transitions are in disagreement with calculations in which the reaction is treated as sequential charge exchange through the free pion-nucleon amplitude, while for T/sub ..pi../ > 200 MeV the anomalous features of the 164 MeV data are not apparent. This is evidence for significant higher order contributions to the double-charge-exchange amplitude near the reasonable energy. Two theoretical approaches that include two nucleon processes are applied to the DIAS data. 64 references.

  5. Spectral Diagnostics of Galactic and Stellar X-Ray Emission from Charge Exchange Recombination

    NASA Technical Reports Server (NTRS)

    Wargelin, B.

    2003-01-01

    The proposed research uses the electron beam ion trap at the Lawrence Livermore National Laboratory to study the X-ray emission from charge-exchange recombination of highly charged ions with neutral gases. The resulting data fill a void in the existing experimental and theoretical data and are needed to explain all or part of the observed X-ray emission from the Galactic Ridge, solar and stellar winds, the Galactic Center, supernova ejecta, and photoionized nebulae.

  6. Absolute elastic differential electron scattering cross sections for He - A proposed calibration standard from 5 to 200 eV

    NASA Technical Reports Server (NTRS)

    Register, D. F.; Trajmar, S.; Srivastava, S. K.

    1980-01-01

    Absolute differential, integral, and momentum-transfer cross sections for electrons elastically scattered from helium are reported for the impact energy range of 5 to 200 eV. Angular distributions for elastically scattered electrons are measured in a crossed-beam geometry using a collimated, differentially pumped atomic-beam source which requires no effective-path-length correction. Below the first inelastic threshold the angular distributions were placed on an absolute scale by use of a phase-shift analysis. Above this threshold, the angular distributions from 10 to 140 deg were fitted using the phase-shift technique, and the resulting integral cross sections were normalized to a semiempirically derived integral elastic cross section. Depending on the impact energy, the data are estimated to be accurate to within 5 to 9%.

  7. Coherent control of charge exchange in strong-field dissociation of LiF

    NASA Astrophysics Data System (ADS)

    Armstrong, Greg; Esry, Brett

    2016-05-01

    The alkali-metal-halides family of molecules are useful prototypes in the study of laser-assisted charge exchange. Typically these molecules possess a field-free crossing between the ionic and covalent diabatic Born-Oppenheimer potential curves, leading to Li+ + F- and Li + F in LiF. These channels are energetically well-separated from higher-lying potentials, and may be easily distinguished experimentally. Moreover, charge exchange involves non-adiabatic transitions between the ionic and covalent channels, thereby allowing the investigation of physics beyond the Born-Oppenheimer approximation. The focus of this work is to control the preference between ionic and covalent dissociative products. We solve the time-dependent Schrödinger equation for the nuclear motion in full dimensionality, and investigate a pump-probe scheme for charge-exchange control. The degree of control is investigated by calculating the kinetic-energy release spectrum as a function of pump-probe delay for the ionic and covalent fragments. This work is supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

  8. Observations of solar wind ion charge exchange in the comet Halley coma

    NASA Technical Reports Server (NTRS)

    Fuselier, S. A.; Shelley, E. G.; Goldstein, B. E.; Goldstein, R.; Neugebauer, M.; Ip, W.-H.; Balsiger, H.; Reme, H.

    1991-01-01

    Giotto Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) observations of solar wind ions show charge exchange effects and solar wind compositional changes in the coma of comet Halley. As the comet was approached, the He(++) to proton density ratio increased until about 1 hour before closest approach after which time it decreased. Abrupt increases in this ratio were also observed in the beginning and near the end of the so-called Mystery Region (8.6 - 5.5(10)(exp 5) km from the comet along the spacecraft trajectory). These abrupt increases in the density ratio were well correlated with enhanced fluxes of keV electrons as measured by the Giotto plasma electron spectrometer. The general increase and then decrease of the He(++) to proton density ratio is quantitatively consistent with a combination of the addition of protons of cometary origin to the plasma and loss of plasma through charge exchange of protons and He(++). In general agreement with the solar wind proton and He(++) observations, solar wind oxygen and carbon ions were observed to charge exchange from higher to lower charge states with decreasing distance to the comet. The more abrupt increases in the He(++) to proton and the He(++) to O(6+) density ratios in the mystery region require a change in the solar wind ion composition in this region while the correlation with energetic electrons indicates processes associated with the comet.

  9. Charge exchange spectroscopy system calibration for ion temperature measurement in KSTARa)

    NASA Astrophysics Data System (ADS)

    Ko, Won-Ha; Lee, Hyungho; Seo, Dongcheol; Kwon, Myeun

    2010-10-01

    The charge exchange spectroscopy (CES) system including collection assemblies, lens design, and cassettes for the KSTAR experiment was installed to obtain profiles of the ion temperature and the toroidal rotation velocity from charge exchange emission between plasma ions and beam neutrals near the plasma axis by using a modulated neutral beam and a background system. We can measure the charge exchange spectra of an impurity line such as the 529 nm line of carbon VI to get ion temperature and rotation profiles in KSTAR. The CES and background systems will have absolute intensity and spectral calibrations using a calibrated source and various spectral lamps. The calibration was done inside the tokamak after all CES systems are installed and the optical systems are slid into the cassettes. This requires that the diagnostic systems are installed near the vacuum vessel inside the cryostat maintaining the superconducting state of the superconducting coils. Repeated spectral calibrations of the spectrometer and charge coupled device for CES will be made in the diagnostic room during the experimental campaign. We show a detailed description of the KSTAR CES system, how to calibrate, and the results of calibration.

  10. Modeling the Hydrogen-Proton Charge-Exchange Process in Global Heliospheric Simulations

    NASA Astrophysics Data System (ADS)

    DeStefano, A.; Heerikhuisen, J.

    2015-12-01

    The environment surrounding our Solar System has a vast and dynamic structure. As the Sun rounds the Milky Way galaxy, interstellar dust and gas interact with the Sun's outflow of solar wind. A bubble of hot plasma forms around the Sun due to this interaction, called the heliosphere. In order to understand the structure of the heliosphere, observations and simulations must work in tandem. Within the past decade or so, 3D models of the heliosphere have been developed exhibiting non- symmmetric as well as predicting structures such as the hydrogen wall and the IBEX ribbon. In this poster we explore new ways to compute charge-exchange source terms. The charge-exchange process is the coupling mechanism between the MHD and kinetic theories. The understanding of this process is crucial in order to make valuable predictions. Energy dependant cross section terms will aid in settling non-linear affects coupling the intestellar and solar particles. Through these new ways of computing source terms, resolving fine structures in the plasma in the heliopause may be possible. In addition, other non-trivial situations, such as charge-exchange mediated shocks, may be addressed.

  11. Unresolved puzzles in the x-ray emission produced by charge exchange measured on electron beam ion traps

    SciTech Connect

    Beiersdorfer, P.; Brown, G. V.; Clementson, J.; Kilbourne, C. A.; Kelley, R. L.; Leutenegger, M. A.; Porter, F. S.; Schweikhard, L.

    2013-04-19

    Charge exchange recombination, the transfer of one or more electrons from an atomic or molecular system to a positive ion, is a common phenomenon affecting laboratory and astrophysical plasmas. Controlled studies of this process in electron beam ion traps during the past one and a half decades have produced multiple observations that are difficult to explain with available spectral models. Some of the most recent observations are so puzzling that they bring in doubt the existence of a coherent predictive capability for line formation by charge exchange, making investigations of charge exchange a fertile ground for continued measurements and theoretical development.

  12. Observed Limits on Charge Exchange Contributions to the Diffuse X-Ray Background

    NASA Technical Reports Server (NTRS)

    Crowder, S. G.; Barger, K. A.; Brandl, D. E.; Eckart, M. E.; Galeazzi, M.; Kelley, R. L.; Kilbourne, C. A.; McCammon, D.; Pfendner, C. G.; Porter, F. S.; Rocks, L.; Szymkowiak, A. E.; Teplin, I. M.

    2012-01-01

    We present a high-resolution spectrum of the diffuse X-ray background from 0.1 to 1 keV for an approximately 1 sr region of the sky centered at l = 90 degrees b = +60 degrees using a 36 pixel array of microcalorimeters flown on a sounding rocket. With an energy resolution of 11 eV FWHM below 1 keV, the spectrum s observed line ratios help separate charge exchange contributions originating within the heliosphere from thermal emission of hot gas in the interstellar medium. The X-ray sensitivity below 1 keV was reduced by about a factor of four from contamination that occurred early in the flight, limiting the significance of the results. The observed centroid of helium-like O VII is 568 (sup +2 (sub -3) eV at 90% confidence. Since the centroid expected for thermal emission is 568.4 eV and for charge exchange is 564.2 eV, thermal emission appears to dominate for this line complex. The dominance of thermal emission is consistent with much of the high-latitude O VII emission originating in 2-3 x 10(exp 6) K gas in the Galactic halo. On the other hand, the observed ratio of C VI Lygamma to Lyalpha is 0.3 plus or minus 0.2. The expected ratios are 0.04 for thermal emission and 0.24 for charge exchange, indicating that charge exchange must contribute strongly to this line and therefore potentially to the rest of the ROSAT R12 band usually associated with 10(sup 6) K emission from the Local Hot Bubble. The limited statistics of this experiment and systematic uncertainties due to the contamination require only greater than 32% thermal emission for O VII and greater than 20% from charge exchange for C VI at the 90% confidence level. An experimental gold coating on the silicon substrate of the array greatly reduced extraneous signals induced on nearby pixels from cosmic rays passing through the substrate, reducing the triggered event rate by a factor of 15 from a previous flight of the instrument.

  13. Measurement of the antineutrino neutral-current elastic differential cross section

    SciTech Connect

    Aguilar-Arevalo, A.  A.; Brown, B.  C.; Bugel, L.; Cheng, G.; Church, E.  D.; Conrad, J.  M.; Dharmapalan, R.; Djurcic, Z.; Finley, D.  A.; Ford, R.; Garcia, F.  G.; Garvey, G.  T.; Grange, J.; Huelsnitz, W.; Ignarra, C.; Imlay, R.; Johnson, R.  A.; Karagiorgi, G.; Katori, T.; Kobilarcik, T.; Louis, W.  C.; Mariani, C.; Marsh, W.; Mills, G.  B.; Mirabal, J.; Moore, C.  D.; Mousseau, J.; Nienaber, P.; Osmanov, B.; Pavlovic, Z.; Perevalov, D.; Polly, C.  C.; Ray, H.; Roe, B.  P.; Russell, A.  D.; Shaevitz, M.  H.; Spitz, J.; Stancu, I.; Tayloe, R.; Van de Water, R.  G.; Wascko, M.  O.; White, D.  H.; Wickremasinghe, D.  A.; Zeller, G.  P.; Zimmerman, E.  D.

    2015-01-08

    We report the measurement of the flux-averaged antineutrino neutral current elastic scattering cross section (dσν-barN→ν-barN/dQ2) on CH2 by the MiniBooNE experiment using the largest sample of antineutrino neutral current elastic candidate events ever collected. The ratio of the antineutrino to neutrino neutral current elastic scattering cross sections and a ratio of the antineutrino neutral current elastic to antineutrino charged current quasi elastic cross sections are also presented.

  14. Measurement of the antineutrino neutral-current elastic differential cross section

    DOE PAGESBeta

    Aguilar-Arevalo, A.  A.; Brown, B.  C.; Bugel, L.; Cheng, G.; Church, E.  D.; Conrad, J.  M.; Dharmapalan, R.; Djurcic, Z.; Finley, D.  A.; Ford, R.; et al

    2015-01-08

    We report the measurement of the flux-averaged antineutrino neutral current elastic scattering cross section (dσν-barN→ν-barN/dQ2) on CH2 by the MiniBooNE experiment using the largest sample of antineutrino neutral current elastic candidate events ever collected. The ratio of the antineutrino to neutrino neutral current elastic scattering cross sections and a ratio of the antineutrino neutral current elastic to antineutrino charged current quasi elastic cross sections are also presented.

  15. Charge-exchange reaction by Reggeon exchange and W{sup +}W{sup −}-fusion

    SciTech Connect

    Schicker, R.

    2015-04-10

    Charge-exchange reactions at high energies are examined. The existing cross section data on the Reggeon induced reaction pp → n + Δ{sup ++} taken at the ZGS and ISR accelerators are extrapolated to the energies of the RHIC and LHC colliders. The interest in the charge-exchange reaction induced by W{sup ±}-fusion is presented, and the corresponding QCD-background is examined.

  16. Differential cross-sections for elastic and inelastic electron scattering from fundamental polyatomic molecules

    NASA Astrophysics Data System (ADS)

    Khakoo, Murtadha A.

    2011-10-01

    The near-threshold scattering of electrons from polyatomic molecules of fundamental interest, e.g. water, primary alcohols and ring molecules e.g. furan, benzene are important in plasma fuel processes, plasmas used in biological processes e.g. in the treatment of skin diseases, astrophysical plasmas, etc. The determination of cross-sections for such molecules has gathered impetus because of the increasing number of applications industrial plasma and biomedical processes and the need to understand and model these complex processes. It is now possible to determine accurate differential cross-sections for electron scattering from these polyatomic molecules. We will present recent normalized, absolute low energy electron scattering differential cross-sections for near-threshold elastic and inelastic scattering from water, primary alcohols, furan and benzene using a well-tested electron spectrometer apparatus. We will also compare our results with those of other experiments and available theoretical models, which show an encouragingly overall improved picture in terms of agreement between the different research groups. Funded by the National Science Foundation Research in an Undergraduate Institution Grant #s 0653452 and 1135203. This work was done collaboratively with Drs. V. Mckoy and C. Winstead, Caltech, USA (National Science Foundation Grant # 0653396 and Office of Basic Energy Sciences, US DOE Grant) and Dr. M. C. A. Lopes, U. Fed. de Juiz de Fora, Minas Gerais, Brazil; Dr. M. H. F. Bettega, U. Fed. do Parana, Curitiba, Brazil Drs. R. F. da Costa and M. A. P. Lima, Universidade Estadual de Campinas UNICAMP and CTBE, Campinas, Brazil (CNPq, FAPESP, FAPEMG, Finep, CENAPAD-SP and CAPES grants). Funded by US-NSF Grant #s 0653452 and 1135203.

  17. Charge-exchange plasma environment for an ion drive spacecraft. [a model for describing mercury ion engines and its effect on spacecraft subsystems

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.; Carruth, M. R., Jr.

    1979-01-01

    The charge exchange plasma environment around a spacecraft that uses mercury ion thrusters for propulsion is described. The interactions between the plasma environment and the spacecraft are determined and a model which describes the propagation of the mercury charge exchange plasma is discussed. The model is extended to describe the flow of the molybdenum component of the charge exchange plasma. The uncertainties in the models for various conditions are discussed and current drain to the solar array, charge exchange plasma material deposition, and the effects of space plasma on the charge exchange plasma propagation are addressed.

  18. Measurement of the antineutrino neutral-current elastic differential cross section

    NASA Astrophysics Data System (ADS)

    Aguilar-Arevalo, A. A.; Brown, B. C.; Bugel, L.; Cheng, G.; Church, E. D.; Conrad, J. M.; Dharmapalan, R.; Djurcic, Z.; Finley, D. A.; Ford, R.; Garcia, F. G.; Garvey, G. T.; Grange, J.; Huelsnitz, W.; Ignarra, C.; Imlay, R.; Johnson, R. A.; Karagiorgi, G.; Katori, T.; Kobilarcik, T.; Louis, W. C.; Mariani, C.; Marsh, W.; Mills, G. B.; Mirabal, J.; Moore, C. D.; Mousseau, J.; Nienaber, P.; Osmanov, B.; Pavlovic, Z.; Perevalov, D.; Polly, C. C.; Ray, H.; Roe, B. P.; Russell, A. D.; Shaevitz, M. H.; Spitz, J.; Stancu, I.; Tayloe, R.; Van de Water, R. G.; Wascko, M. O.; White, D. H.; Wickremasinghe, D. A.; Zeller, G. P.; Zimmerman, E. D.; MiniBooNE Collaboration

    2015-01-01

    We report the measurement of the flux-averaged antineutrino neutral current elastic scattering cross section (d σν ¯N →ν ¯N/d Q2) on CH2 by the MiniBooNE experiment using the largest sample of antineutrino neutral current elastic candidate events ever collected. The ratio of the antineutrino to neutrino neutral current elastic scattering cross sections and a ratio of the antineutrino neutral current elastic to antineutrino charged current quasielastic cross sections are also presented.

  19. Possible Charge-Exchange X-Ray Emission in the Cygnus Loop Detected with Suzaku

    NASA Technical Reports Server (NTRS)

    Katsuda, Satoru; Tsunemi, Hiroshi; Mori, Koji; Uchida, Hiroyuki; Kosugi, Hiroko; Kimura, Masashi; Nakajima, Hiroshi; Takakura, Satoru; Petre, Robert; Hewitt. John W.; Yamaguchi, Hiroya

    2011-01-01

    X-ray spectroscopic measurements of the Cygnus Loop supernova remnant indicate that metal abundances throughout most of the remnant s rim are depleted to approx.0.2 times the solar value. However, recent X-ray studies have revealed in some narrow regions along the outermost rim anomalously "enhanced" abundances (up to approx. 1 solar). The reason for these anomalous abundances is not understood. Here, we examine X-ray spectra in annular sectors covering nearly the entire rim of the Cygnus Loop using Suzaku (21 pointings) and XMM-Newton (1 pointing). We find that spectra in the "enhanced" abundance regions commonly show a strong emission feature at approx.0.7 keV. This feature is likely a complex of He-like O K(gamma + delta + epsilon), although other possibilities cannot be fully excluded. The intensity of this emission relative to He-like O K(alpha) appears to be too high to be explained as thermal emission. This fact, as well as the spatial concentration of the anomalous abundances in the outermost rim, leads us to propose an origin from charge-exchange processes between neutrals and H-like O. We show that the presence of charge-exchange emission could lead to the inference of apparently "enhanced" metal abundances using pure thermal emission models. Accounting for charge-exchange emission, the actual abundances could be uniformly low throughout the rim. The overall abundance depletion remains an open question. Subject headings: ISM: abundances ISM: individual objects (Cygnus Loop) ISM: supernova remnants X-rays: ISM atomic processes

  20. Critical validity assessment of theoretical models: charge-exchange at intermediate and high energies

    NASA Astrophysics Data System (ADS)

    Belkić, Dževad

    1999-06-01

    Exact comprehensive computations are carried out by means of four leading second-order approximations yielding differential cross sections dQ/ dΩ for the basic charge exchange process H ++H(1s)→H(1s)+H + at intermediate and high energies. The obtained extensive set of results is thoroughly tested against all the existing experimental data with the purpose of critically assessing the validity of the boundary corrected second-Born (CB2), continuum-distorted wave (CDW), impulse approximation (IA) and the reformulated impulse approximation (RIA). The conclusion which emerges from this comparative study clearly indicates that the RIA agrees most favorably with the measurements available over a large energy range 25 keV-5 MeV. Such a finding reaffirms the few-particle quantum scattering theory which imposes several strict conditions on adequate second-order methods. These requirements satisfied by the RIA are: (i) normalisations of all the scattering wave functions, (ii) correct boundary conditions in both entrance and exit channels, (iii) introduction of a mathematically justified two-center continuum state for the sum of an attractive and a repulsive Coulomb potential with the same interaction strength, (iv) inclusion of the multiple scattering effects neglected in the IA, (v) a proper description of the Thomas double scattering in good agreement with the experiments and without any unobserved peak splittings. Nevertheless, the performed comparative analysis of the above four approximations indicates that none of the methods is free from some basic shortcomings. Despite its success, the RIA remains essentially a high-energy model like the other three methods under study. More importantly, their perturbative character leaves virtually no room for further systematic improvements, since the neglected higher-order terms are prohibitively tedious for practical purposes and have never been computed exactly. To bridge this gap, we presently introduce the variational Pad

  1. Oxygen ionization rates at Mars and Venus - Relative contributions of impact ionization and charge exchange

    NASA Technical Reports Server (NTRS)

    Zhang, M. H. G.; Luhmann, J. G.; Nagy, A. F.; Spreiter, J. R.; Stahara, S. S.

    1993-01-01

    Oxygen ion production rates above the ionopauses of Venus and Mars are calculated for photoionization, charge exchange, and solar wind electron impact ionization processes. The latter two require the use of the Spreiter and Stahara (1980) gas dynamic model to estimate magnetosheath velocities, densities, and temperatures. The results indicate that impact ionization is the dominant mechanism for the production of O(+) ions at both Venus and Mars. This finding might explain both the high ion escape rates measured by Phobos 2 and the greater mass loading rate inferred for Venus from the bow shock positions.

  2. Analysis of charge-exchange spectroscopy data by combining genetic and Gauss-Newton algorithms

    NASA Astrophysics Data System (ADS)

    Qian, Ma; Haoyi, Zuo; Yanling, Wei; Liang, Liu; Wenjin, Chen; Xiaoxue, He; Shirong, Luo

    2015-11-01

    The temperature and rotation velocity profile of ions in a tokamak are two characteristic parameters that reflect the plasma's behavior. Measurement of the two parameters relies on analyzing an active charge exchange spectroscopy diagnostic. However, a very challenging problem in such a diagnostic is the existence of interfering spectral lines, which can mislead the spectrum analysis process. This work proposes combining a genetic algorithm with the Gauss-Newton method (GAGN) to address this problem. Using this GAGN algorithm, we can effectively distinguish between the useful spectrum line and the interfering spectral lines within the spectroscopic output. The accuracy and stability of this algorithm are verified using both numerical simulation and actual measurements.

  3. Laser interferometric measurement of ion electrode shape and charge exchange erosion

    NASA Technical Reports Server (NTRS)

    Macrae, Gregory S.; Mercer, Carolyn R.

    1991-01-01

    A projected fringe profilometry system was applied to surface contour measurements of an accelerator electrode from an ion thrustor. The system permitted noncontact, nondestructive evaluation of the fine and gross structure of the electrode. A 3-D surface map of a dished electrode was generated without altering the electrode surface. The same system was used to examine charge exchange erosion pits near the periphery of the electrode to determine the depth, location, and volume of material lost. This electro-optical measurement system allowed rapid, nondestructive, digital data acquisition coupled with automated computer data processing. In addition, variable sensitivity allowed both coarse and fine measurements of objects having various surface finishes.

  4. Laser interferometric measurement of ion electrode shape and charge exchange erosion

    NASA Technical Reports Server (NTRS)

    Macrae, Gregory S.; Mercer, Carolyn R.

    1991-01-01

    A novel projected fringe profilometry system was applied to surface contour measurements of an accelerator electrode from an ion thruster. The system permitted noncontact, nondestructive evaluation of the fine and gross structure of the electrode. A 3D surface map of a dished electrode was generated without altering the electrode surface. The same system was used to examine charge exchange erosion pits near the periphery of the electrode to determine the depth, location, and volume of material lost. This electro-optical measurement system allowed rapid nondestructive digital data acquisition coupled with automated computer data-processing. In addition, variable sensitivity allowed both coarse and fine measurements of objects having various surface finishes.

  5. Optical system design for the charge exchange spectroscopy of the Korea superconducting tokamak advanced research device

    NASA Astrophysics Data System (ADS)

    Oh, Seungtae; Ko, Won-Ha

    2011-04-01

    The collective optical design is described for the charge exchange spectroscopy (CES) of the Korea superconducting tokamak advanced research (KSTAR) device. The CES diagnostic measures the ion temperature of carbon and other impurities, in conjunction with the neutral heating beam in KSTAR. The visible light from the plasma is concentrated via collection optics and imaged onto quartz fibers. The collection optics in the system is the key component for the CES system. The final design is derived through four steps and its performance is examined in a simulation step. In this paper, the design details of the collective optical system for the KSTAR CES are discussed.

  6. A photodiode-based neutral particle bolometer for characterizing charge-exchanged fast-ion behavior

    SciTech Connect

    Clary, R.; Smirnov, A.; Dettrick, S.; Knapp, K.; Korepanov, S.; Ruskov, E.; Heidbrink, W. W.; Zhu, Y.

    2012-10-15

    A neutral particle bolometer (NPB) has been designed and implemented on Tri Alpha Energy's C-2 device in order to spatially and temporally resolve the charge-exchange losses of fast-ion populations originating from neutral beam injection into field-reversed configuration plasmas. This instrument employs a silicon photodiode as the detection device with an integrated tungsten filter coating to reduce sensitivity to light radiation. Here we discuss the technical aspects and calibration of the NPB, and report typical NPB measurement results of wall recycling effects on fast-ion losses.

  7. A photodiode-based neutral particle bolometer for characterizing charge-exchanged fast-ion behaviora)

    NASA Astrophysics Data System (ADS)

    Clary, R.; Smirnov, A.; Dettrick, S.; Knapp, K.; Korepanov, S.; Ruskov, E.; Heidbrink, W. W.; Zhu, Y.

    2012-10-01

    A neutral particle bolometer (NPB) has been designed and implemented on Tri Alpha Energy's C-2 device in order to spatially and temporally resolve the charge-exchange losses of fast-ion populations originating from neutral beam injection into field-reversed configuration plasmas. This instrument employs a silicon photodiode as the detection device with an integrated tungsten filter coating to reduce sensitivity to light radiation. Here we discuss the technical aspects and calibration of the NPB, and report typical NPB measurement results of wall recycling effects on fast-ion losses.

  8. A photodiode-based neutral particle bolometer for characterizing charge-exchanged fast-ion behavior.

    PubMed

    Clary, R; Smirnov, A; Dettrick, S; Knapp, K; Korepanov, S; Ruskov, E; Heidbrink, W W; Zhu, Y

    2012-10-01

    A neutral particle bolometer (NPB) has been designed and implemented on Tri Alpha Energy's C-2 device in order to spatially and temporally resolve the charge-exchange losses of fast-ion populations originating from neutral beam injection into field-reversed configuration plasmas. This instrument employs a silicon photodiode as the detection device with an integrated tungsten filter coating to reduce sensitivity to light radiation. Here we discuss the technical aspects and calibration of the NPB, and report typical NPB measurement results of wall recycling effects on fast-ion losses.

  9. Fast time resolution charge-exchange measurements during the fishbone instability in the poloidal divertor experiment

    SciTech Connect

    Beiersdorfer, P.; Kaita, R.; Goldston, R.J.

    1984-01-01

    Measurements of fast ion losses due to the fishbone instability during high ..beta../sub T/q neutral beam heated discharges in the Poloidal Divertor Experiment have been made using two new vertical-viewing charge-exchange analyzers. The measurements show that the instability has an n=1 toroidal mode number, and that it ejects beam ions in a toroidally rotating beacon directed outward along a major radius. Observations of ejected ions with energies up to twice the beam injection energy at R approx. = R/sub 0/ + a indicate the presence of a non-..mu..-conserving acceleration mechanism.

  10. Oxygen ionization rates at Mars and Venus - Relative contributions of impact ionization and charge exchange

    NASA Astrophysics Data System (ADS)

    Zhang, M. H. G.; Luhmann, J. G.; Nagy, A. F.; Spreiter, J. R.; Stahara, S. S.

    1993-02-01

    Oxygen ion production rates above the ionopauses of Venus and Mars are calculated for photoionization, charge exchange, and solar wind electron impact ionization processes. The latter two require the use of the Spreiter and Stahara (1980) gas dynamic model to estimate magnetosheath velocities, densities, and temperatures. The results indicate that impact ionization is the dominant mechanism for the production of O(+) ions at both Venus and Mars. This finding might explain both the high ion escape rates measured by Phobos 2 and the greater mass loading rate inferred for Venus from the bow shock positions.

  11. Helium measurements simulating alpha-particle diagnostics by the pellet charge exchange in Large Helical Device

    NASA Astrophysics Data System (ADS)

    Ozaki, T.; Goncharov, P.; Veschev, E.; Sudo, S.; Tamura, N.; ,

    2008-03-01

    It is very important to investigate the confinement of α particle, which is produced by the nuclear reaction in ITER or fusion reactor. The pellet charge exchange measurement (PCX) is one of the most powerful methods because it can directly provide the profile of α particle energy spectra in plasma. In Large Helical Device (LHD), it is possible to confine the high energetic particle (helium) accelerated by using the ion cyclotron resonance heating (ICH). Therefore it is possible to perform the simulation experiment of α particle diagnostic in LHD.

  12. Spectral Diagnostics of Galactic and Stellar X-Ray Emission from Charge Exchange Recombination

    NASA Technical Reports Server (NTRS)

    Wargelin, B.

    2002-01-01

    The proposed research uses the electron beam ion trap at the Lawrence Livermore National Laboratory (LLNL) to study X-ray emission from charge-exchange recombination of highly charged ions with neutral gases. The resulting data fill a void in existing experimental and theoretical understanding of this atomic physics process, and are needed to explain all or part of the observed X-ray emission from the soft X-ray background, stellar winds, the Galactic Center, supernova ejecta, and photoionized nebulae. Progress made during the first year of the grant is described, as is work planned for the second year.

  13. The observation of charge exchange of pions captured in several nuclei

    NASA Astrophysics Data System (ADS)

    Bassalleck, B.; Corriveau, F.; Hasinoff, M. D.; Marks, T.; Measday, D. F.; Poutissou, J.-M.; Salomon, M.

    1981-06-01

    We have measured for the first time the branching ratios of the charge exchange of stopped negative pions in targets of 6Li, Al, Ti, Cu, Nb and Pb. These branching ratios are of the order of 10 -6, about an order of magnitude smaller than the upper limit previously established. Using the branching ratio for radiative pion capture in 6Li to the ground state of 6He we obtain the Panofsky ratio in 6Li, P6 = (8.7 ± 2.3) × 10 -4.

  14. ({sup 18}O,{sup 18}Ne) double charge-exchange with MAGNEX

    SciTech Connect

    Bondí, M.; Cappuzzello, F.; Nicolosi, D.; Tropea, S.; Agodi, C.; Carbone, D.; Cavallaro, M.; Cunsolo, A.; De Napoli, M.; Foti, A.

    2014-05-09

    An experimental study concerning Double Gamow-Teller (DGT) modes in ({sup 18}O,{sup 18}Ne) Double Charge-Exchange reactions has been very recently performed at INFN-LNS laboratory in Catania. The experiment was performed using a {sup 40}Ca solid target and a {sup 18}O Cyclotron beam at 270 MeV incident energy. Charged ejectiles produced in the reaction were momentum analyzed and identified by MAGNEX spectrometer at very forward angles. Preliminary results are presented in the present paper.

  15. Molecular target and projectile angular scattering effects in stopping power and charge exchange at low-to-intermediate projectile energies

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, R.; Öhrn, Y.; Sabin, John R.; Deumens, E.

    2002-02-01

    We analyze the implications of the molecular structure of a target and the angular scattering effects on projectile-target collisions within the Electron-Nuclear Dynamics (END) approach. We show the suitability of the END method for the analysis of molecular scattering processes such as differential cross sections, charge exchange, and energy loss as required for the study of the stopping cross section. As a consequence of these effects, we show that the rovibronic energy loss becomes of greatest importance at low projectile energies. Furthermore, we find that the Bragg additivity rule and the linear-velocity dependence of the stopping cross section are not fulfilled at low projectile energies. Finally, we analyze the differences in the scattering processes for molecular and atomic targets, and show that in a transmission experiment with small exit window, the acceptance angle corresponds to different impact parameter selection for molecular targets than for atomic ones. Thus, the measured stopping cross section becomes a function of the acceptance angle of the experimental setup. We present results for hydrogen beams on H2 and N2 gas targets.

  16. Water-molecule fragmentation induced by charge exchange in slow collisions with He{sup +} and He{sup 2+} ions in the keV-energy region

    SciTech Connect

    Cabrera-Trujillo, R.; Deumens, E.; Oehrn, Y.; Quinet, O.; Sabin, J. R.; Stolterfoht, N.

    2007-05-15

    Charge exchange and fragmentation in the collision systems He{sup 2+}+H{sub 2}O and He{sup +}+H{sub 2}O are theoretically investigated at projectile energies of a few keV. The calculations are based on the electron nuclear dynamics (END) method which solves the time-dependent Schroedinger equation. Total and differential cross sections for charge exchange are evaluated by averaging over 10 orientations of the H{sub 2}O molecule. Summed total electron capture cross sections are found to be in good agreement with available experimental data. Projectile scattering was studied in the full angular range with respect to the incident beam direction. The theory provides a description of the fragmentation mechanisms such as Coulomb explosion and binary collision processes. For impact parameters below 3.5 a.u., we find that single and double electron capture occurs, resulting always in full fragmentation of H{sub 2}O independent of the target orientation for {sup 3}He{sup 2+} ions. Hydrogen and oxygen fragments and its respective ions, are studied as a function of emission angle and energy. In the binary collisions regime the theoretical results are found to be in excellent agreement with previous experimental data. In the Coulomb explosion regime the theoretical data are found to peak at specific angles including 90 degree sign , which is consistent with the experiment.

  17. Water-molecule fragmentation induced by charge exchange in slow collisions with He+ and He2+ ions in the keV-energy region

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, R.; Deumens, E.; Öhrn, Y.; Quinet, O.; Sabin, J. R.; Stolterfoht, N.

    2007-05-01

    Charge exchange and fragmentation in the collision systems He2++H2O and He++H2O are theoretically investigated at projectile energies of a few keV. The calculations are based on the electron nuclear dynamics (END) method which solves the time-dependent Schrödinger equation. Total and differential cross sections for charge exchange are evaluated by averaging over 10 orientations of the H2O molecule. Summed total electron capture cross sections are found to be in good agreement with available experimental data. Projectile scattering was studied in the full angular range with respect to the incident beam direction. The theory provides a description of the fragmentation mechanisms such as Coulomb explosion and binary collision processes. For impact parameters below 3.5a.u. , we find that single and double electron capture occurs, resulting always in full fragmentation of H2O independent of the target orientation for He2+3 ions. Hydrogen and oxygen fragments and its respective ions, are studied as a function of emission angle and energy. In the binary collisions regime the theoretical results are found to be in excellent agreement with previous experimental data. In the Coulomb explosion regime the theoretical data are found to peak at specific angles including 90°, which is consistent with the experiment.

  18. High spatial and temporal resolution charge exchange recombination spectroscopy on the HL-2A tokamak.

    PubMed

    Wei, Y L; Yu, D L; Liu, L; Ida, K; von Hellermann, M; Cao, J Y; Sun, A P; Ma, Q; Chen, W J; Liu, Yi; Yan, L W; Yang, Q W; Duan, X R; Liu, Yong

    2014-10-01

    A 32/64-channel charge exchange recombination spectroscopy (CXRS) diagnostic system is developed on the HL-2A tokamak (R = 1.65 m, a = 0.4 m), monitoring plasma ion temperature and toroidal rotation velocity simultaneously. A high throughput spectrometer (F/2.8) and a pitch-controlled fiber bundle enable the temporal resolution of the system up to 400 Hz. The observation geometry and an optimized optic system enable the highest radial resolution up to ∼1 cm at the plasma edge. The CXRS system monitors the carbon line emission (C VI, n = 8-7, 529.06 nm) whose Doppler broadening and Doppler shift provide ion temperature and plasma rotation velocity during the neutral beam injection. The composite CX spectral data are analyzed by the atomic data and analysis structure charge exchange spectroscopy fitting (ADAS CXSFIT) code. First experimental results are shown for the case of HL-2A plasmas with sawtooth oscillations, electron cyclotron resonance heating, and edge transport barrier during the high-confinement mode (H-mode).

  19. High spatial and temporal resolution charge exchange recombination spectroscopy on the HL-2A tokamak

    NASA Astrophysics Data System (ADS)

    Wei, Y. L.; Yu, D. L.; Liu, L.; Ida, K.; von Hellermann, M.; Cao, J. Y.; Sun, A. P.; Ma, Q.; Chen, W. J.; Liu, Yi; Yan, L. W.; Yang, Q. W.; Duan, X. R.; Liu, Yong

    2014-10-01

    A 32/64-channel charge exchange recombination spectroscopy (CXRS) diagnostic system is developed on the HL-2A tokamak (R = 1.65 m, a = 0.4 m), monitoring plasma ion temperature and toroidal rotation velocity simultaneously. A high throughput spectrometer (F/2.8) and a pitch-controlled fiber bundle enable the temporal resolution of the system up to 400 Hz. The observation geometry and an optimized optic system enable the highest radial resolution up to ˜1 cm at the plasma edge. The CXRS system monitors the carbon line emission (C VI, n = 8-7, 529.06 nm) whose Doppler broadening and Doppler shift provide ion temperature and plasma rotation velocity during the neutral beam injection. The composite CX spectral data are analyzed by the atomic data and analysis structure charge exchange spectroscopy fitting (ADAS CXSFIT) code. First experimental results are shown for the case of HL-2A plasmas with sawtooth oscillations, electron cyclotron resonance heating, and edge transport barrier during the high-confinement mode (H-mode).

  20. First measurement of the edge charge exchange recombination spectroscopy on EAST tokamak

    NASA Astrophysics Data System (ADS)

    Li, Y. Y.; Yin, X. H.; Fu, J.; Jiang, D.; Feng, S. Y.; Lyu, B.; Shi, Y. J.; Yi, Y.; Zhou, X. J.; Hu, C. D.; Ye, M. Y.; Wan, B. N.

    2016-11-01

    An edge toroidal charge exchange recombination spectroscopy (eCXRS) diagnostic, based on a heating neutral beam injection (NBI), has been deployed recently on the Experimental Advanced Superconducting Tokamak (EAST). The eCXRS, which aims to measure the plasma ion temperature and toroidal rotation velocity in the edge region simultaneously, is a complement to the exiting core CXRS (cCXRS). Two rows with 32 fiber channels each cover a radial range from ˜2.15 m to ˜2.32 m with a high spatial resolution of ˜5-7 mm. Charge exchange emission of Carbon VI CVI at 529.059 nm induced by the NBI is routinely observed, but can be tuned to any interested wavelength in the spectral range from 400 to 700 nm. Double-slit fiber bundles increase the number of channels, the fibers viewing the same radial position are binned on the CCD detector to improve the signal-to-noise ratio, enabling shorter exposure time down to 5 ms. One channel is connected to a neon lamp, which provides the real-time wavelength calibration on a shot-to-shot basis. In this paper, an overview of the eCXRS diagnostic on EAST is presented and the first results from the 2015 experimental campaign will be shown. Good agreements in ion temperature and toroidal rotation are obtained between the eCXRS and cCXRS systems.

  1. Charge-exchange X-ray emission of nearby star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Liu, Jiren; Wang, Q. Daniel; Mao, Shude

    2012-03-01

    Properties of hot gas outflows from galaxies are generally measured from associated X-ray line emission assuming that it represents atomic transitions in thermally excited hot gas. X-ray line emission, however, can also arise from the charge exchange between highly ionized ions and neutral species. The Kα triplet of He-like ions can be used as a powerful diagnostic, because the charge-exchange X-ray emission (CXE) favours the intercombination and forbidden lines, while the thermal emission favours the resonance line. We analyse the O VII triplet of a sample of nine nearby star-forming galaxies observed by the XMM-Newton Reflection Grating Spectrometers. For most galaxies, the forbidden lines are comparable to or stronger than the resonance lines, which is in contrast to the thermal prediction. For NGC 253, M51, M83, M61, NGC 4631, and the Antennae (Arp 244), the observed line ratios are consistent with the ratio of CXE; for M94 and NGC 2903, the observed ratios indicate multiple origins; for M82, different regions show different line ratios, also indicating multiple origins. We discuss other possible mechanisms that can produce a relatively strong forbidden line, such as a collisional non-equilibrium-ionization recombining/ionizing plasma, which are not favoured. These results suggest that the CXE may be a common phenomenon and contribute a significant fraction of the soft X-ray line emission for galaxies with massive star formation.

  2. Charge Exchange Contribution to the Decay of the Ring Current, Measured by Energetic Neutral Atoms (ENAs)

    NASA Technical Reports Server (NTRS)

    Jorgensen, A. M.; Henderson, M. G.; Roelof, E. C.; Reeves, G. D.; Spence, H. E.

    2001-01-01

    In this paper we calculate the contribution of charge exchange to the decay of the ring current. Past works have suggested that charge exchange of ring current protons is primarily responsible for the decay of the ring current during the late recovery phase, but there is still much debate about the fast decay of the early recovery phase. We use energetic neutral atom (ENA) measurements from Polar to calculate the total ENA energy escape. To get the total ENA escape we apply a forward modeling technique, and to estimate the total ring current energy escape we use the Dessler-Parker-Sckopke relationship. We find that during the late recovery phase of the March 10, 1998 storm ENAs with energies greater than 17.5 keV can account for 75% of the estimated energy loss from the ring current. During the fast recovery the measured ENAs can only account for a small portion of the total energy loss. We also find that the lifetime of the trapped ions is significantly shorter during the fast recovery phase than during the late recovery phase, suggesting that different processes are operating during the two phases.

  3. Charge exchange of low-energy ions in thin carbon foils

    NASA Technical Reports Server (NTRS)

    Buergi, Alfred; Oetliker, Michael; Bochsler, Peter; Geiss, Johannes; Coplan, Michael A.

    1990-01-01

    In order to calibrate a time-of-flight mass spectrometer which is to be flown in the solar wind, the charge exchange properties of low-energy ions in thin carbon foils have been investigated. Incident ions of He, C, N, O, Ne, and Ar with energies in the range 0.5-2 keV/nucleon have been used to measure charge-state distribution, residual energy, and angular distribution after transmission through thin (1-6 microgram/sq cm) carbon foils. Within such foils, an equilibrium between ionization and recombination of the projectile is rapidly established, and, consequently, the charge state of the emerging particle depends essentially on its residual velocity. A comparison of the charge exchange properties of Ne-22 with Ne-20 demonstrates that indeed the velocity (and not the energy) of the emerging particle determines its final charge. A comparison of properties of different elements provides an indication of an electron shell effect. Predictions for the energy loss of ions within the carbon foils made with the TRIM code are in good agreement with the experimental results presented in this paper.

  4. Observations of solar wind ion charge exchange in the Comet Halley coma

    NASA Technical Reports Server (NTRS)

    Fuselier, S. A.; Shelley, E. G.; Goldstein, B. E.; Goldstein, R.; Neugebauer, M.; Ip, W.-H.; Balsiger, H.; Reme, H.

    1991-01-01

    Giotto Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) observations of solar wind ions show charge exchange effects and solar wind compositional changes in the coma of Comet Halley. As the comet was approached, the He(2+) to proton density ratio increased from 2.5 percent in the solar wind to about 4 percent about 1 hr before closest approach after which time it decreased to about 1 percent. Abrupt increases in this ratio from 2.5 to 4.5 percent were also observed in the beginning and near the end of the so-called Mystery Region. These abrupt increases in the density ratio were well correlated with enhanced fluxes of keV electrons as measured by the Giotto plasma electron spectrometer. The general increase and then decrease of the He(2+) to proton density ratio is quantitatively consistent with a combination of the addition of protons of Cometary origin to the plasma and loss of plasma through charge exchange of protons and He(2+).

  5. A comprehensive model of ion diffusion and charge exchange in the cold Io torus

    NASA Technical Reports Server (NTRS)

    Barbosa, D. D.; Moreno, M. A.

    1988-01-01

    A comprehensive analytic model of radial diffusion in the cold Io torus is developed. The model involves a generalized molecular cloud theory of SO2 and its dissociation fragments SO, O2, S, and O, which are formed at a relatively large rate by solar UV photodissociation of SO2. The key component of the new theory is SO, which can react with S(+) through a near-resonant charge exchange process that is exothermic. This provides a mechanism for the rapid depletion of singly ionized sulfur in the cold torus and can account for the large decrease in the total flux tube content inward of Io's orbit. The model is used to demonstrate quantitatively the effects of radial diffusion in a charge exchange environment that acts as a combined source and sink for ions in various charge states. A detailed quantitative explanation for the O(2+) component of the cold torus is given, and insight is derived into the workings of the so-called plasma 'ribbon'.

  6. Development of two-grating spectrometer for the charge exchange spectroscopy system on KSTAR

    NASA Astrophysics Data System (ADS)

    Lee, Hyungho; Song, Eun-ji; Park, Young-dong; Oh, Soo-ghee; Ko, Won-Ha

    2011-06-01

    The charge exchange spectroscopy (CES) system on Korea Superconducting Tokamak Advanced Research (KSTAR) was installed last year and had been applied to measure the C VI ion temperature and rotation velocity profiles. The ion temperature and rotation velocity profiles had been estimated from the C VI 5290.5 Å (n = 8-7) charge-exchange spectrum signal measured by a Czerny-Turner type spectrometer and a thinned back-illuminated charge coupled device (CCD) camera. However, the Czerny-Turner type spectrometer used for the KSTAR CES system showed so low signal to noise ratio for KSTAR plasmas in the 2010 experimental campaign that the time resolution of the CES system had been limited to 100 ms due to the increased exposure time of the attached CCD camera. Then, new two-grating spectrometer had been developed in order to improve the time resolution of the CES system. The spectrometer consists of two gratings (1200 g/mm and 1800 g/mm each) with additive configuration, concave mirrors (f = 50 cm), and a cylindrical lens (f = 50 cm). The time resolution of the CES system increases by a factor of 2-4 with the two-grating spectrometer. The C VI ion temperature and rotation velocity profiles obtained by the two-grating spectrometer are compared to those by Czerny-Turner type spectrometer in this paper.

  7. Laser-Controlled Antihydrogen Production by Two-Stage Charge Exchange

    SciTech Connect

    Storry, C.H.; Comeau, D.; George, M.; Hessels, E.A.; Guise, N.; Levitt, B.; Le Sage, D.; Speck, A.; Gabrielse, G.; Grzonka, D.; Oelert, W.; Schepers, G.; Sefzick, T.; Pittner, H.; Herrmann, M.; Walz, J.; Haensch, T.W.

    2005-10-26

    Our ATRAP collaboration has now demonstrated a second technique for antihydrogen (H-bar) production. Lasers are used for the first time to control the production of H-baratoms in our cryogenic apparatus at CERN. As suggested in ref. [2] and first reported in ref. [1], lasers excite a thermal beam of cesium (Cs) atoms to a Rydberg state. In a first charge exchange collision one of these laser-excited Cs atoms (Cs*) and a cold e+ produces positronium (Ps). Our measurements at Harvard([3]) and at CERN([1]) confirm CTMC simulations([2]) that the laser-selected binding energy in the Cs atom is preserved by the collision and results in Ps with the selected binding energy. A second charge exchange is between one of these Ps atoms and a trapped p-bar. H-baris produced by this second collision and is expected to again have the same binding energy. One advantage of this technique as discussed in ref. [2] is that the H-barproduced is expected to be extremely cold, at the temperature of the trapped p-bar, allowing for possible confinement of the H-baratoms in a magnetic trap.

  8. Dynamics of the fully stripped ion-hydrogen atom charge exchange process in dense quantum plasmas

    SciTech Connect

    Zhang, Ling-yu; Wan, Jiang-feng; Zhao, Xiao-ying; Xiao, Guo-qing; Duan, Wen-shan; Qi, Xin; Yang, Lei

    2014-09-15

    The plasma screening effects of dense quantum plasmas on charge exchange processes of a fully stripped ion colliding with a hydrogen atom are studied by the classical trajectory Monte Carlo method. The inter-particle interactions are described by the exponential cosine-screened Coulomb potentials. It is found that in weak screening conditions, cross sections increase with the increase of the ionic charge Z. However, in strong screening conditions, the dependence of cross sections on the ionic charge is related to the incident particle energy. At high energies, cross sections show a linear increase with the increase of Z, whereas at low energies, cross sections for Z≥4 become approximately the same. The He{sup 2+} and C{sup 6+} impacting charge exchange cross sections in dense quantum plasmas are also compared with those in weakly coupled plasmas. The interactions are described by the static screened Coulomb potential. It is found that for both He{sup 2+} and C{sup 6+}, the oscillatory screening effects of dense quantum plasmas are almost negligible in weak screening conditions. However, in strong screening conditions, the oscillatory screening effects enhance the screening effects of dense quantum plasmas, and the enhancement becomes more and more significant with the increase of the screening parameter and the ionic charge.

  9. Development of two-grating spectrometer for the charge exchange spectroscopy system on KSTAR

    SciTech Connect

    Lee, Hyungho; Song, Eun-ji; Oh, Soo-ghee; Park, Young-dong; Ko, Won-Ha

    2011-06-15

    The charge exchange spectroscopy (CES) system on Korea Superconducting Tokamak Advanced Research (KSTAR) was installed last year and had been applied to measure the C VI ion temperature and rotation velocity profiles. The ion temperature and rotation velocity profiles had been estimated from the C VI 5290.5 A (n = 8-7) charge-exchange spectrum signal measured by a Czerny-Turner type spectrometer and a thinned back-illuminated charge coupled device (CCD) camera. However, the Czerny-Turner type spectrometer used for the KSTAR CES system showed so low signal to noise ratio for KSTAR plasmas in the 2010 experimental campaign that the time resolution of the CES system had been limited to 100 ms due to the increased exposure time of the attached CCD camera. Then, new two-grating spectrometer had been developed in order to improve the time resolution of the CES system. The spectrometer consists of two gratings (1200 g/mm and 1800 g/mm each) with additive configuration, concave mirrors (f = 50 cm), and a cylindrical lens (f = 50 cm). The time resolution of the CES system increases by a factor of 2-4 with the two-grating spectrometer. The C VI ion temperature and rotation velocity profiles obtained by the two-grating spectrometer are compared to those by Czerny-Turner type spectrometer in this paper.

  10. High spatial and temporal resolution charge exchange recombination spectroscopy on the HL-2A tokamak

    SciTech Connect

    Wei, Y. L.; Yu, D. L. Liu, L.; Cao, J. Y.; Sun, A. P.; Ma, Q.; Chen, W. J.; Liu, Yi; Yan, L. W.; Yang, Q. W.; Duan, X. R.; Liu, Yong; Ida, K.; Hellermann, M. von

    2014-10-01

    A 32/64-channel charge exchange recombination spectroscopy (CXRS) diagnostic system is developed on the HL-2A tokamak (R = 1.65 m, a = 0.4 m), monitoring plasma ion temperature and toroidal rotation velocity simultaneously. A high throughput spectrometer (F/2.8) and a pitch-controlled fiber bundle enable the temporal resolution of the system up to 400 Hz. The observation geometry and an optimized optic system enable the highest radial resolution up to ~1 cm at the plasma edge. The CXRS system monitors the carbon line emission (C VI, n = 8–7, 529.06 nm) whose Doppler broadening and Doppler shift provide ion temperature and plasma rotation velocity during the neutral beam injection. The composite CX spectral data are analyzed by the atomic data and analysis structure charge exchange spectroscopy fitting (ADAS CXSFIT) code. First experimental results are shown for the case of HL-2A plasmas with sawtooth oscillations, electron cyclotron resonance heating, and edge transport barrier during the high-confinement mode (H-mode)

  11. Development of two-grating spectrometer for the charge exchange spectroscopy system on KSTAR.

    PubMed

    Lee, Hyungho; Song, Eun-ji; Park, Young-dong; Oh, Soo-ghee; Ko, Won-Ha

    2011-06-01

    The charge exchange spectroscopy (CES) system on Korea Superconducting Tokamak Advanced Research (KSTAR) was installed last year and had been applied to measure the C VI ion temperature and rotation velocity profiles. The ion temperature and rotation velocity profiles had been estimated from the C VI 5290.5 Å (n = 8-7) charge-exchange spectrum signal measured by a Czerny-Turner type spectrometer and a thinned back-illuminated charge coupled device (CCD) camera. However, the Czerny-Turner type spectrometer used for the KSTAR CES system showed so low signal to noise ratio for KSTAR plasmas in the 2010 experimental campaign that the time resolution of the CES system had been limited to 100 ms due to the increased exposure time of the attached CCD camera. Then, new two-grating spectrometer had been developed in order to improve the time resolution of the CES system. The spectrometer consists of two gratings (1200 g/mm and 1800 g/mm each) with additive configuration, concave mirrors (f = 50 cm), and a cylindrical lens (f = 50 cm). The time resolution of the CES system increases by a factor of 2-4 with the two-grating spectrometer. The C VI ion temperature and rotation velocity profiles obtained by the two-grating spectrometer are compared to those by Czerny-Turner type spectrometer in this paper.

  12. Charge exchange in a planetary corona - Its effect on the distribution and escape of hydrogen

    NASA Technical Reports Server (NTRS)

    Chamberlain, J. W.

    1977-01-01

    The theory for a spherical collisionless planetary corona is extended to include charge-exchange collisions between H(+) and H, which are assumed to constitute intermingled gases with different kinetic temperatures. The treatment is based on the conventional concept of a critical level (or exobase) above which the only collisions considered in the Boltzmann equation are those that resonantly exchange charge. Although the geometry treated is an oversimplification for a real planet, numerical examples are given for an idealized earth and Venus. For earth, an ion temperature of 4 times the neutral temperature, an ion density at the exobase of 14,000 per cu cm, and a plasmapause at 1.5 earth radii will raise the escape flux of H by a factor of 6. The total H above the exobase is changed by less than 1%. For Venus, conditions are examined that would account for the peculiar H distribution observed from Mariner 5. The plasma conditions required are not obviously outrageous by terrestrial standards, but the Mariner 5 ionosphere measurements did not show a high plasmapause at, say, 1.25 or 1.5 planetary radii, a fact that might argue against a charge-exchange model.

  13. Determination of plasma ion velocity distribution via charge-exchange recombination spectroscopy

    SciTech Connect

    Fonck, R.J.; Darrow, D.S.; Jaehnig, K.P.

    1983-12-01

    Spectroscopy of line radiation from plasma impurity ions excited by charge-exchange recombination reactions with energetic neutral beam atoms is rapidly becoming recognized as a powerful technique for measuring ion temperature, bulk plasma motion, impurity transport, and more exotic phenomena such as fast alpha particle distributions. In particular, this diagnostic offers the capability of obtaining space- and time-resolved ion temperature and toroidal plasma rotation profiles with relatively simple optical systems. Cascade-corrected excitation rate coefficients for use in both fully stripped impurity density studies and ion temperature measurements have been calculated to the principal ..delta..n = 1 transitions of He+, C/sup 5 +/, and O/sup 7 +/ with neutral beam energies of 5 to 100 keV/amu. A fiber optically coupled spectrometer system has been used on PDX to measure visible He/sup +/ radiation excited by charge exchange. Central ion temperatures up to 2.4 keV and toroidal rotation speeds up to 1.5 x 10/sup 7/ cm/s were observed in diverted discharges with P/sub INJ/ less than or equal to 3.0 MW.

  14. Determination of plasma-ion velocity distribution via charge-exchange recombination spectroscopy

    NASA Astrophysics Data System (ADS)

    Fonck, R. J.; Darrow, D. S.; Jaehnig, K. P.

    1984-06-01

    Spectroscopy of line radiation from plasma impurity ions excited by charge-exchange recombination reactions with energetic neutral-beam atoms is rapidly becoming recognized as a powerful diagnostic for magnetically confined tokamak plasmas. Ion temperature, bulk plasma motion, impurity transport, and more exotic phenomena such as fast alpha-particle distributions can all be measured with this technique. In particular, it offers the capability of obtaining space- and time-resolved ion temperature and toroidal plasma rotation profiles with relatively simple optical systems. Cascade-corrected excitation rate coefficients for use in both fully stripped impurity density studies and ion-temperature measurements have been calculated for the principal Δn=1 transitions of He+, C5+, and O7+ with neutral-beam energies of 5-100 keV/amu. Line intensities and profiles can be affected by atomic fine structure, l-mixing collisions, motional Stark effects, and product ions created in the neutral-beam region which drift into the viewing sightline. General estimates of the importance of these effects for the transitions of interest are provided, along with specific examples calculated for the PDX (Poloidal Divertor Experiment) and TFTR (Tokamak Fusion Test Reactor) tokamaks. A fiber optically coupled spectrometer system has been used on PDX to measure visible He+ radiation excited by charge exchange to illustrate some of these points. Central ion temperatures up to 2.4 keV and toroidal rotation speeds up to 1.5×107 cm/s were observed.

  15. CHARGE-EXCHANGE LIMITS ON LOW-ENERGY {alpha}-PARTICLE FLUXES IN SOLAR FLARES

    SciTech Connect

    Hudson, H. S.; Fletcher, L.; MacKinnon, A. L.; Woods, T. N.

    2012-06-20

    This paper reports on a search for flare emission via charge-exchange radiation in the wings of the Ly{alpha} line of He II at 304 A, as originally suggested for hydrogen by Orrall and Zirker. Via this mechanism a primary {alpha} particle that penetrates into the neutral chromosphere can pick up an atomic electron and emit in the He II bound-bound spectrum before it stops. The Extreme-ultraviolet Variability Experiment on board the Solar Dynamics Observatory gives us our first chance to search for this effect systematically. The Orrall-Zirker mechanism has great importance for flare physics because of the essential roles that particle acceleration plays; this mechanism is one of the few proposed that would allow remote sensing of primary accelerated particles below a few MeV nucleon{sup -1}. We study 10 events in total, including the {gamma}-ray events SOL2010-06-12 (M2.0) and SOL2011-02-24 (M3.5) (the latter a limb flare), seven X-class flares, and one prominent M-class event that produced solar energetic particles. The absence of charge-exchange line wings may point to a need for more complete theoretical work. Some of the events do have broadband signatures, which could correspond to continua from other origins, but these do not have the spectral signatures expected from the Orrall-Zirker mechanism.

  16. Upgrade of the Edge Charge Exchange Diagnostic on Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    McDermott, Rachael; Lipschultz, Bruce; Marr, Kenneth

    2006-10-01

    The current edge Charge Exchange Spectroscopy system is being upgraded to include both a beam viewing and a background viewing toroidal periscope. The beam viewing periscope will be focused on the center of the DNB and will cover a 4cm radial region at the edge of the plasma starting a few centimeters in from and extending up to 1centimeter outside of the last closed flux surface. The background periscope will view the same radial region but will be displaced toroidally by 36 degrees. Each periscope has 20 chordal views with a radial resolution of 2.5-3mm. The presence of a background periscope obviates the need for a chopped DNB by providing time synchronized background B^+4 spectral data that can be subtracted directly from the active beam-derived B^+4 line-shapes. This system has been designed to work in conjunction with the current poloidal Charge Exchange periscope which has 25 fibers focused in the same region with equivalent radial resolution. The new toroidal system will enable concurrent measurements of the poloidal and toroidal velocity as well as the temperature and density of the B^+5 ions in the edge pedestal region; a measurement that currently does not exist on C-Mod. This information will then be used to calculate radial electric field profiles and study edge physics phenomena.

  17. Charge exchange collisions of slow C6 + with atomic and molecular H

    NASA Astrophysics Data System (ADS)

    Saha, Bidhan C.; Guevara, Nicolais L.; Sabin, John R.; Deumens, Erik; Öhrn, Yngve

    2016-04-01

    Charge exchange in collisions of C6+ ions with H and H2 is investigated theoretically at projectile energies 0.1 < E < 10 keV/amu, using electron nuclear dynamics (END) - a semi-classical approximation which not only includes electron translation factors for avoiding spurious couplings but also employs full dynamical trajectories to treat nuclear motions. Both the total and partial cross sections are reported for the collision of C6+ ions with atomic and molecular hydrogen. A comparison with other theoretical and experimental results shows, in general good agreement except at very low energy, considered here. For H2, the one- and two-electron charge exchange cross sections are calculated and compared with other theoretical and experimental results. Small but non-negligible isotope effects are found at the lowest energy studied in the charge transfer of C6+ with H. In low energy region, it is observed that H2 has larger isotope effects than H atom due to the polarizability effect which is larger than the mass effect.

  18. Laboratory Measurements of Solar-Wind/Comet X-Ray Emission and Charge Exchange Cross Sections

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Cadez, I.; Greenwood, J. B.; Mawhorter, R. J.; Smith, S. J.; Lozano, J.

    2002-01-01

    The detection of X-rays from comets such as Hyakutake, Hale-Bopp, d Arrest, and Linear as they approach the Sun has been unexpected and exciting. This phenomenon, moreover, should be quite general, occurring wherever a fast solar or stellar wind interacts with neutrals in a comet, a planetary atmosphere, or a circumstellar cloud. The process is, O(+8) + H2O --> O(+7*) + H2O(+), where the excited O(+7*) ions are the source of the X-ray emissions. Detailed modeling has been carried out of X-ray emissions in charge-transfer collisions of heavy solar-wind Highly Charged Ions (HCIs) and interstellar/interplanetary neutral clouds. In the interplanetary medium the solar wind ions, including protons, can charge exchange with interstellar H and He. This can give rise to a soft X-ray background that could be correlated with the long-term enhancements seen in the low-energy X-ray spectrum of ROSAT. Approximately 40% of the soft X-ray background detected by Exosat, ROSAT, Chandra, etc. is due to Charge Exchange (CXE): our whole heliosphere is glowing in the soft X-ray due to CXE.

  19. Differential, integral, and momentum-transfer cross sections for elastic electron scattering by neon - 5 to 100 eV

    NASA Technical Reports Server (NTRS)

    Register, D. F.; Trajmar, S.

    1984-01-01

    Relative elastic-scattering differential cross sections were measured in the 5-100-eV impact energy and 10-145 deg angular ranges. Normalization of these cross sections was achieved by utilizing accurate total electron-scattering cross sections. A phase-shift analysis of the angular distributions in terms of real phase shifts has been carried out. From the differential cross sections, momentum-transfer cross sections were obtained and the values of the critical energy and angle were established (associated with the lowest value of the differential cross section) as 62.5 + or - 2.5 eV and 101.7 deg + or - 1.5 deg, respectively. The present phase shifts, the critical parameters, and differential, integral, and momentum-transfer cross sections are compared to previous experimental and theoretical results. The error associated with the present data is about 10 percent.

  20. [Particle Size and Number Density Online Analysis for Particle Suspension with Polarization-Differentiation Elastic Light Scattering Spectroscopy].

    PubMed

    Chen, Wei-kang; Fang, Hui

    2016-03-01

    The basic principle of polarization-differentiation elastic light scattering spectroscopy based techniques is that under the linear polarized light incidence, the singlely scattered light from the superficial biological tissue and diffusively scattered light from the deep tissue can be separated according to the difference of polarization characteristics. The novel point of the paper is to apply this method to the detection of particle suspension and, to realize the simultaneous measurement of its particle size and number density in its natural status. We design and build a coaxial cage optical system, and measure the backscatter signal at a specified angle from a polystyrene microsphere suspension. By controlling the polarization direction of incident light with a linear polarizer and adjusting the polarization direction of collected light with another linear polarizer, we obtain the parallel polarized elastic light scattering spectrum and cross polarized elastic light scattering spectrum. The difference between the two is the differential polarized elastic light scattering spectrum which include only the single scattering information of the particles. We thus compare this spectrum to the Mie scattering calculation and extract the particle size. We then also analyze the cross polarized elastic light scattering spectrum by applying the particle size already extracted. The analysis is based on the approximate expressions taking account of light diffusing, from which we are able to obtain the number density of the particle suspension. We compare our experimental outcomes with the manufacturer-provided values and further analyze the influence of the particle diameter standard deviation on the number density extraction, by which we finally verify the experimental method. The potential applications of the method include the on-line particle quality monitoring for particle manufacture as well as the fat and protein density detection of milk products.

  1. [Particle Size and Number Density Online Analysis for Particle Suspension with Polarization-Differentiation Elastic Light Scattering Spectroscopy].

    PubMed

    Chen, Wei-kang; Fang, Hui

    2016-03-01

    The basic principle of polarization-differentiation elastic light scattering spectroscopy based techniques is that under the linear polarized light incidence, the singlely scattered light from the superficial biological tissue and diffusively scattered light from the deep tissue can be separated according to the difference of polarization characteristics. The novel point of the paper is to apply this method to the detection of particle suspension and, to realize the simultaneous measurement of its particle size and number density in its natural status. We design and build a coaxial cage optical system, and measure the backscatter signal at a specified angle from a polystyrene microsphere suspension. By controlling the polarization direction of incident light with a linear polarizer and adjusting the polarization direction of collected light with another linear polarizer, we obtain the parallel polarized elastic light scattering spectrum and cross polarized elastic light scattering spectrum. The difference between the two is the differential polarized elastic light scattering spectrum which include only the single scattering information of the particles. We thus compare this spectrum to the Mie scattering calculation and extract the particle size. We then also analyze the cross polarized elastic light scattering spectrum by applying the particle size already extracted. The analysis is based on the approximate expressions taking account of light diffusing, from which we are able to obtain the number density of the particle suspension. We compare our experimental outcomes with the manufacturer-provided values and further analyze the influence of the particle diameter standard deviation on the number density extraction, by which we finally verify the experimental method. The potential applications of the method include the on-line particle quality monitoring for particle manufacture as well as the fat and protein density detection of milk products. PMID:27400522

  2. Colliding planetary and stellar winds: charge exchange and transit spectroscopy in neutral hydrogen

    NASA Astrophysics Data System (ADS)

    Tremblin, Pascal; Chiang, Eugene

    2013-01-01

    When transiting their host stars, hot Jupiters absorb about 10 per cent of the light in the wings of the stellar Lyman α emission line. The absorption occurs at wavelengths Doppler-shifted from line centre by ±100 km s-1 - larger than the thermal speeds with which partially neutral, ˜104 K hydrogen escapes from hot Jupiter atmospheres. It has been proposed that the absorption arises from ˜106 K hydrogen from the host stellar wind, made momentarily neutral by charge exchange with planetary H i. The ±100 km s-1 velocities would then be attributed to the typical velocity dispersions of protons in the stellar wind - as inferred from spacecraft measurements of the solar wind. To test this proposal, we perform 2D hydrodynamic simulations of colliding hot Jupiter and stellar winds, augmented by a chemistry module to compute the amount of hot neutral hydrogen produced by charge exchange. We observe the contact discontinuity where the two winds meet to be Kelvin-Helmholtz unstable. The Kelvin-Helmholtz instability mixes the two winds; in the mixing layer, charge exchange reactions establish, within tens of seconds, a chemical equilibrium in which the neutral fraction of hot stellar hydrogen equals the neutral fraction of cold planetary hydrogen (about 20 per cent). In our simulations, enough hot neutral hydrogen is generated to reproduce the transit observations, and the amount of absorption converges with both spatial resolution and time. Our calculations support the idea that charge transfer between colliding winds correctly explains the Lyman α transit observations - modulo the effects of magnetic fields, which we do not model but which may suppress mixing. Other neglected effects include, in order of decreasing importance, rotational forces related to orbital motion, gravity and stellar radiation pressure; we discuss quantitatively the errors introduced by our approximations. How hot stellar hydrogen cools when it collides with cold planetary hydrogen is also

  3. High resolution main-ion charge exchange spectroscopy in the DIII-D H-mode pedestal

    NASA Astrophysics Data System (ADS)

    Grierson, B. A.; Burrell, K. H.; Chrystal, C.; Groebner, R. J.; Haskey, S. R.; Kaplan, D. H.

    2016-11-01

    A new high spatial resolution main-ion (deuterium) charge-exchange spectroscopy system covering the tokamak boundary region has been installed on the DIII-D tokamak. Sixteen new edge main-ion charge-exchange recombination sightlines have been combined with nineteen impurity sightlines in a tangentially viewing geometry on the DIII-D midplane with an interleaving design that achieves 8 mm inter-channel radial resolution for detailed profiles of main-ion temperature, velocity, charge-exchange emission, and neutral beam emission. At the plasma boundary, we find a strong enhancement of the main-ion toroidal velocity that exceeds the impurity velocity by a factor of two. The unique combination of experimentally measured main-ion and impurity profiles provides a powerful quasi-neutrality constraint for reconstruction of tokamak H-mode pedestals.

  4. STUDIES OF X-RAY PRODUCTION FOLLOWING CHARGE EXCHANGE RECOMBINATION BETWEEN HIGHLY CHARGED IONS AND NEUTRAL ATOMS AND MOLECULES

    SciTech Connect

    Brown, G V; Beiersdorfer, P; Chen, H; Clementson, J; Frankel, M; Gu, M F; Kelley, R L; Kilbourne, C A; Porter, F S; Thorn, D B; Wargelin, B J

    2008-08-28

    We have used microcalorimeters built by the NASA/Goddard Space Flight Center and the Lawrence Livermore National Laboratory Electron Beam Ion Trap to measure X-ray emission produced by charge exchange reactions between highly charged ions colliding with neutral helium, hydrogen, and nitrogen gas. Our measurements show the spectral dependence on neutral species and also show the distinct differences between spectra produced by charge exchange reactions and those produced by direct impact excitation. These results are part of an ongoing experimental investigation at the LLNL EBIT facility of charge exchange spectral signatures and can be used to interpret X-ray spectra produced by a variety of laboratory and celestial sources including cometary and planetary atmospheres, the Earth's magnetosheath, the heliosphere, and tokamaks.

  5. A comet's tale: Role of charge exchange in the plasma environment of comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Wedlund, Cyril Simon; Kallio, Esa; Alho, Markku; Dyadechkin, Sergey; Nilsson, Hans; Stenberg Wieser, Gabriella; Béhar, Etienne; Gunell, Herbert; Holmström, Mats

    2015-04-01

    On 6 Aug. 2014, the Rosetta mission arrived in the vicinity of comet 67P/Churyumov-Gerasimenko (C-G) and started measuring its complex plasma environment, using notably the RPC-ICA ion spectrometer (Rosetta Plasma Consortium Ion Composition Analyser). A simple model of charge-exchange processes is first presented for He2+ and H+ solar wind ions that efficiently convert them into He+ ions (measured by RPC-ICA) and H energetic neutral atoms, respectively. In a second step, we present a new cometary hybrid plasma model, taking into account photoionisation, charge-exchange, electron impact ionisation and electron recombination, dedicated to the interpretation of RPC-ICA measurements. We use this global model to investigate in more detail the role of the water production rate and charge-exchange processes in the formation of plasma regions at comet 67P/C-G and for various heliocentric distances.

  6. Transport, charge exchange and loss of energetic heavy ions in the earth's radiation belts - Applicability and limitations of theory

    NASA Technical Reports Server (NTRS)

    Spjeldvik, W. N.

    1981-01-01

    Computer simulations of processes which control the relative abundances of ions in the trapping regions of geospace are compared with observations from discriminating ion detectors. Energy losses due to Coulomb collisions between ions and exospheric neutrals are considered, along with charge exchange losses and internal charge exchanges. The time evolution of energetic ion fluxes of equatorially mirroring ions under radial diffusion is modelled to include geomagnetic and geoelectric fluctutations. Limits to the validity of diffusion transport theory are discussed, and the simulation is noted to contain provisions for six ionic charge states and the source effect on the radiation belt oxygen ion distributions. Comparisons are made with ion flux data gathered on Explorer 45 and ISEE-1 spacecraft and results indicate that internal charge exchanges cause the radiation belt ion charge state to be independent of source charge rate characteristics, and relative charge state distribution is independent of the radially diffusive transport rate below the charge state redistribution zone.

  7. What can be Learned from X-Ray Spectroscopy Concerning Hot Gas in the Local Bubble and Charge Exchange Processes

    NASA Technical Reports Server (NTRS)

    Snowden, Steven L.

    2007-01-01

    Solar wind charge exchange produces diffuse X-ray emission with a variable surface brightness comparable to that of the cosmic background. While the temporal variation of the charge exchange emission allows some separation of the components, there remains a great deal of uncertainty as to the zero level of both. Because the production mechanisms of the two components are considerably different, their spectra would provide critical diagnostics to the understanding of both. However, current X-ray observatories are very limited in both spectral resolution and sensitivity in the critical soft X-ray (less than 1.0 keV) energy range. Non-dispersive high-resolution spectrometers, such as the calorimeter proposed for the Spectrum Roentgen Gamma mission, will be extremely useful in distinguishing the cascade emission of charge exchange from the spectra of thermal bremsstrahlung cosmic plasmas.

  8. Absolute elastic differential electron scattering cross sections in the intermediate energy region. III - SF6 and UF6

    NASA Technical Reports Server (NTRS)

    Srivastava, S. K.; Trajmar, S.; Chutjian, A.; Williams, W.

    1976-01-01

    A recently developed technique has been used to measure the ratios of elastic differential electron scattering cross sections (DCS) for SF6 and UF6 to those of He at electron impact energies of 5, 10, 15, 20, 30, 40, 50, 60, and 75 eV and at scattering angles of 20 to 135 deg. In order to obtain the absolute values of DCS from these ratios, He DCS of McConkey and Preston have been employed in the 20 to 90 deg range. At angles in the 90 to 135 deg range the recently determined cross sections of Srivastava and Trajmar have been utilized. From these DCS, elastic integral and momentum transfer cross sections have been obtained.

  9. Models of Heliospheric solar wind charge exchange X-ray emission

    NASA Astrophysics Data System (ADS)

    Koutroumpa, Dimitra

    2016-04-01

    The first models of the solar wind charge exchange (SWCX) X-ray production in the heliosphere were developed shortly after the discovery of SWCX emission at the end of 1990s. Since then, continuous monitoring of the global solar wind evolution through the solar cycle has allowed better constraints on its interaction with the interstellar neutrals. We have a fairly accurate description of the interstellar neutral density distributions in interplanetary space. However, the solar wind heavy ion fluxes, and especially their short term variability and propagation through interplanetary space, have remained relatively elusive due to the sparseness or lack of in situ data, especially towards high ecliptic latitudes. In this talk, I will present a summary the heliospheric SWCX modeling efforts, and an overview of the global solar cycle variability of heliospheric SWCX emission, while commenting on the difficulties of modeling the real-time variability of the heliospheric X-ray signal.

  10. New Missions and the Future of Solar Wind Charge Exchange Studies

    NASA Astrophysics Data System (ADS)

    Kuntz, K. D.

    2016-04-01

    Several newly approved missions in astrophysics and heliophysics will study solar wind charge-exchange (SWCX) directly as either primary or secondary science goals. Of these, SMILE and CuPID will study the magnetosheath by means of the SWCX emission and will provide a direct measure of the magnetospheric emission from in both the 1/4 keV and 3/4 keV bands. HaloSAT observations will be designed to minimize the magnetospheric component for its observations of the Galactic Halo, but will make at least some dedicated observations of heliospheric SWCX. I will outline the simulation needs and observational strategies required to study SWCX for astrophysical purposes.

  11. Cometary X-Rays: Line Emission Cross Sections for Multiply Charged Solar Wind Ion Charge Exchange

    SciTech Connect

    Otranto, S; Olson, R E; Beiersdorfer, P

    2006-12-22

    Absolute line emission cross sections are presented for 1 keV/amu charge exchange collisions of multiply charged solar wind ions with H{sub 2}O, H, O, CO{sub 2}, and CO cometary targets. The present calculations are contrasted with available laboratory data. A parameter-free model is used to successfully predict the recently observed x-ray spectra of comet C/LINEAR 1999 S4. We show that the resulting spectrum is extremely sensitive to the time variations of the solar wind composition. Our results suggest that orbiting x-ray satellites may be a viable way to predict the solar wind intensities and composition on the Earth many hours before the ions reach the earth.

  12. Ion temperature by charge exchange neutral analysis from vertical sightlines on the Tokamak Fusion Test Reactor

    SciTech Connect

    Fiore, C.L.; Medley, S.S.; Hammett, G.W.; Kaita, R.; Scott, S.D.

    1987-12-01

    The Fokker-Planck code FPPRF is used to calculate the expected deuterium charge exchange flux along vertical sighlines from TFTR neutral-beam-injected discharges. The feasibility of obtaining central ion temperature measurements by fitting the spectra obtained from these sightlines at two energy regions--above the highest neutral beam injection energy (> 100 keV) and from 20-80 keV--is investigated. It is demonstrated that the central ion temperature can be obtained from the central vertical slightline for fitting the high energy data. The deuterium neutral particle flux energy distribution below the neutral beam injection energy is insentive to the code input ion temperature, however. 6 refs., 12 figs., 1 tab.

  13. Design of charge exchange recombination spectroscopy for the joint Texas experimental tokamak

    SciTech Connect

    Chi, Y.; Zhuang, G. Cheng, Z. F.; Hou, S. Y.; Cheng, C.; Li, Z.; Wang, J. R.; Wang, Z. J.

    2014-11-15

    The old diagnostic neutral beam injector first operated at the University of Texas at Austin is ready for rejoining the joint Texas experimental tokamak (J-TEXT). A new set of high voltage power supplies has been equipped and there is no limitation for beam modulation or beam pulse duration henceforth. Based on the spectra of fully striped impurity ions induced by the diagnostic beam the design work for toroidal charge exchange recombination spectroscopy (CXRS) system is presented. The 529 nm carbon VI (n = 8 − 7 transition) line seems to be the best choice for ion temperature and plasma rotation measurements and the considered hardware is listed. The design work of the toroidal CXRS system is guided by essential simulation of expected spectral results under the J-TEXT tokamak operation conditions.

  14. Inference of the ring current ion composition by means of charge exchange decay

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Hoffman, R. A.; Bewtra, N. K.

    1981-01-01

    The analysis of data from the Explorer 45 (S3-A) electrostatic analyzer in the energy range 5-30 keV has provided some new results on the ring current ion composition. It has been well established that the storm time ring current has a decay time of several days, during which the particle fluxes decrease nearly monotonically. By analyzing the measured ion fluxes during the several day storm recovery period and assuming that beside hydrogen other ions were present and that the decays were exponential in nature, three separate lifetimes for the ions were established. These fitted decay lifetimes are in excellent agreement with the expected charge exchange decay lifetimes for H(+), O(+) and He(+) in the energy and L value range of the data.

  15. Propagation of charge-exchange plasma produced by an ion thruster

    NASA Technical Reports Server (NTRS)

    Carruth, M. R., Jr.; Brady, M. E.

    1981-01-01

    Under the proper conditions there is an end-effect of a long, cylindrical Langmuir probe which allows a significant increase in collected ion current when the probe is aligned with a flowing plasma. This effect was used to determine the charge-exchange plasma flow direction at various locations relative to the ion thruster. The ion current collected by the probe as a function of its angle with respect to the plasma flow allows determination of the plasma density and plasma flow velocity at the probe's location upstream of the ion thruster optics. The density values obtained from the ion current agreed to within a factor of two of density values obtained by typical voltage-current Langmuir probe characteristics.

  16. Spin dipole nuclear matrix elements for double beta decay nuclei by charge-exchange reactions

    NASA Astrophysics Data System (ADS)

    Ejiri, H.; Frekers, D.

    2016-11-01

    Spin dipole (SD) strengths for double beta-decay (DBD) nuclei were studied experimentally for the first time by using measured cross sections of (3He, t) charge-exchange reactions (CERs). Then SD nuclear matrix elements (NMEs) {M}α ({{SD}}) for low-lying 2‑ states were derived from the experimental SD strengths by referring to the experimental α = GT (Gamow–Teller) and α = F (Fermi) strengths. They are consistent with the empirical NMEs M({{SD}}) based on the quasi-particle model with the empirical effective SD coupling constant. The CERs are used to evaluate the SD NME, which is associated with one of the major components of the neutrino-less DBD NME.

  17. Can Charge Exchange Explain Anomalous Soft X-Ray Emission in the Cygnus Loop?

    NASA Astrophysics Data System (ADS)

    Cumbee, R. S.; Henley, D. B.; Stancil, P. C.; Shelton, R. L.; Nolte, J. L.; Wu, Y.; Schultz, D. R.

    2014-06-01

    Recent X-ray studies have shown that supernova shock models are unable to satisfactorily explain X-ray emission in the rim of the Cygnus Loop. In an attempt to account for this "anomalously" enhanced X-ray flux, we fit the region with a model including theoretical charge exchange (CX) data along with shock and background X-ray models. The model includes the CX collisions of O8 +, O7 +, N7 +, N6 +, C6 +, and C5 + with H with an energy of 1 keV u-1 (438 km s-1). The observations reveal a strong emission feature near 0.7 keV that cannot fully be accounted for by a shock model, nor the current CX data. Inclusion of CX, specifically O7 + + H, does provide for a statistically significant improvement over a pure shock model.

  18. Charge-exchange QRPA with the Gogny Force for Axially-symmetric Deformed Nuclei

    SciTech Connect

    Martini, M.; Goriely, S.; Péru, S.

    2014-06-15

    In recent years fully consistent quasiparticle random-phase approximation (QRPA) calculations using finite range Gogny force have been performed to study electromagnetic excitations of several axially-symmetric deformed nuclei up to the {sup 238}U. Here we present the extension of this approach to the charge-exchange nuclear excitations (pnQRPA). In particular we focus on the Isobaric Analog and Gamow-Teller resonances. A comparison of the predicted GT strength distribution with existing experimental data is presented. The role of nuclear deformation is shown. Special attention is paid to β-decay half-lives calculations for which experimental data exist and for specific isotone chains of relevance for the r-process nucleosynthesis.

  19. Neutrino nuclear responses for double beta decays and astro neutrinos by charge exchange reactions

    NASA Astrophysics Data System (ADS)

    Ejiri, Hiroyasu

    2014-09-01

    Neutrino nuclear responses are crucial for neutrino studies in nuclei. Charge exchange reactions (CER) are shown to be used to study charged current neutrino nuclear responses associated with double beta decays(DBD)and astro neutrino interactions. CERs to be used are high energy-resolution (He3 ,t) reactions at RCNP, photonuclear reactions via IAR at NewSUBARU and muon capture reactions at MUSIC RCNP and MLF J-PARC. The Gamow Teller (GT) strengths studied by CERs reproduce the observed 2 neutrino DBD matrix elements. The GT and spin dipole (SD) matrix elements are found to be reduced much due to the nucleon spin isospin correlations and the non-nucleonic (delta isobar) nuclear medium effects. Impacts of the reductions on the DBD matrix elements and astro neutrino interactions are discussed.

  20. Charge-exchange recombination spectroscopy of the plasma ion temperature at the T-10 tokamak

    SciTech Connect

    Krupin, V. A.; Tugarinov, S. N.; Barsukov, A. G.; Dnestrovskij, A. Yu.; Klyuchnikov, L. A.; Korobov, K. V.; Krasnyanskii, S. A.; Naumenko, N. N.; Nemets, A. R.; Sushkov, A. V.; Tilinin, G. N.

    2013-08-15

    Charge-exchange recombination spectroscopy (CXRS) based on a diagnostic neutral beam has been developed at the T-10 tokamak. The diagnostics allows one to measure the ion temperature profile in the cross section of the plasma column. In T-10 experiments, the measurement technique was adjusted and the elements of the CXRS diagnostics for ITER were tested. The used spectroscopic equipment makes it possible to reliably determine the ion temperature from the Doppler broadening of impurity lines (helium, carbon), as well as of the spectral lines of the working gas. The profiles of the plasma ion temperature in deuterium and helium discharges were measured at different plasma currents and densities, including with the use of active Doppler measurements of lines of different elements. The validity and reliability of ion temperature measurements performed by means of the developed CXRS diagnostics are analyzed.

  1. 'Coulomb' description of basic relaxation parameters of isobar analog and charge-exchange giant monopole resonances

    SciTech Connect

    Gorelik, M. L.; Rykovanov, V. S.; Urin, M. G.

    2010-12-15

    Within a semimicroscopic approach, basic relaxation parameters of the isobaric analog resonance and of the charge-exchange giant monopole resonance, which is an overtone of the isobaric analog resonance, are interpreted in terms of the mean Coulomb field of a nucleus. The continuum version of the random-phase approximation, allowance for an approximate isospin conservation in nuclei in an explicit form, and a phenomenological description of the fragmentation effect are basic ingredients of the approach used. The aforementioned parameters were calculated for a number of magic and near-magic nuclei by using a partly self-consistent phenomenological nuclear mean field and the isovector part of the Landau-Migdal interaction in the particle-hole channel. The results of the calculations are compared with corresponding experimental data.

  2. Observation of Solar Wind Charge Exchange Emission from Exospheric Material in and Outside Earth's Magnetosheath

    NASA Technical Reports Server (NTRS)

    Snowden, S. L.; Collier, M. R.; Cravens, T.; Kuntz, K. D.; Lepri, S. T.; Robertson, I.; Tomas, L.

    2008-01-01

    A long XMM-Newton exposure is used to observe solar wind charge exchange (SWCX) emission from exospheric material in and outside Earth s magnetosheath. The light curve of the O VII (0.5-0.62 keV) band is compared with a model for the expected emission, and while the emission is faint and the light curve has considerable scatter, the correlation is significant to better than 99.9%. This result demonstrates the validity of the geocoronal SWCX emission model for predicting a contribution to astrophysical observations to a scale factor of order unity (1.36). The results also demonstrate the potential utility of using X-ray observations to study global phenomena of the magnetosheath which currently are only investigated using in situ measurements.

  3. The sup 11 Li neutron halo radius from pion double charge exchange

    SciTech Connect

    Hayes, A.C.

    1991-01-01

    We have analzed the pion double charge exchange data for the direct population of the ground state of {sup 11}Li by the {sup 11}B({pi}{sup {minus}}, {pi}{sup +}){sup 11}Li reaction and find that the measured cross section determines the rms radius of the last two neutrons in {sup 11}Li to be 5.1{sub {minus} 0.8}{sup +0.6} fm. It is shown that the pion cross-section falls off as the sixth power of the assumed neutron halo radius, so that a radius greater than about 6 fm is ruled out. Indeed, pion double charge is found to act as an unusually sensitive probe of the properties of this exotic neutron rich nucleus. 9 refs., 2 figs.

  4. Impact of calibration technique on measurement accuracy for the JET core charge-exchange system.

    PubMed

    Giroud, Carine; Meigs, A G; Negus, C R; Zastrow, K-D; Biewer, T M; Versloot, T W

    2008-10-01

    The core charge-exchange diagnostic at the Joint European Torus (JET) provides measurements of the impurity ion temperature T(i), toroidal velocity V(phi), and impurity ion densities n(imp), across the whole minor radius. A contribution to the uncertainty of the measured quantities is the error resulting from the multi-Gaussian fit and photon statistics, usually quoted for each measured data. Absolute intensity calibration and especially alignment of the viewing directions can introduce an important systematic error. The technique adopted at JET to reduce this systematic contribution to the error is presented in this paper. The error in T(i), V(phi), and n(imp) is then discussed depending on their use.

  5. Design of charge exchange recombination spectroscopy for the joint Texas experimental tokamak.

    PubMed

    Chi, Y; Zhuang, G; Cheng, Z F; Hou, S Y; Cheng, C; Li, Z; Wang, J R; Wang, Z J

    2014-11-01

    The old diagnostic neutral beam injector first operated at the University of Texas at Austin is ready for rejoining the joint Texas experimental tokamak (J-TEXT). A new set of high voltage power supplies has been equipped and there is no limitation for beam modulation or beam pulse duration henceforth. Based on the spectra of fully striped impurity ions induced by the diagnostic beam the design work for toroidal charge exchange recombination spectroscopy (CXRS) system is presented. The 529 nm carbon VI (n = 8 - 7 transition) line seems to be the best choice for ion temperature and plasma rotation measurements and the considered hardware is listed. The design work of the toroidal CXRS system is guided by essential simulation of expected spectral results under the J-TEXT tokamak operation conditions.

  6. Molecular (Feshbach) treatment of charge exchange Li/sup 3 +/+He collisions. I. Energies and couplings

    SciTech Connect

    Martin, F.; Riera, A.; Yanez, M.

    1986-05-15

    We point out a fundamental difference between the molecular treatment of charge exchange X/sup n/++H(1s) and X/sup n/++He(1s/sup 2/) collisions, which is that the latter process involves molecular states that are formally autoionizing. Then standard ab initio methods do not, in general, yield the relevant wave functions that are needed in the collision treatment, irrespective of whether quasimolecular autoionization be significant or not during the collision. We implement a particularly simple and useful form of the Feshbach formalism to calculate the energies of those two electron systems, and a method to evaluate the corresponding dynamical couplings is presented for the first time. Our implementation of this formalism together with the new computational techniques involved are presented in detail.

  7. Production of Ca/sup -/ through sequential charge exchange with Li vapor

    SciTech Connect

    Alton, G.D.; Kvale, T.J.; Compton, R.N.; Pegg, D.J.; Thompson, J.S.

    1985-01-01

    The efficiencies for producing Ca/sup -/ through sequential charge exchange between Ca/sup +/ projectiles and Li vapor have been measured for the first time. The measurements were made over a projectile energy range of 20 to 100 keV under experimental conditions commensurate with tandem accelerator applications. Production efficiencies in terms of negative ion charge state fractions versus projectile energy, Li vapor cell temperature and Li target density were determined for negative ion formation within a detection window ..cap alpha.. of +-11 mrad. Within this range of angular divergence, the efficiency for production is observed to be an increasing function of the projectile energy even at the highest energies used during the measurements (100 keV). The results of these measurements as well as a description of the experimental apparatus and techniques utilized are presented. 19 refs., 5 figs.

  8. Wave packet methods for charge exchange processes in ion-atom collisions

    NASA Astrophysics Data System (ADS)

    Baloı̈tcha, E.; Desouter-Lecomte, M.; Bacchus-Montabonel, M.-C.; Vaeck, N.

    2001-05-01

    The efficiency of different time-independent and time-dependent wave packet methods to calculate charge-exchange cross sections is discussed. The time-independent spectral projection method is based on the Chebyshev expansion of the resolvent function and represents an interesting alternative to the usual Fourier method which involves a time propagation. On the other hand, the flux operator method still requires propagation in time but uses the properties of absorbing potentials in order to calculate the flux operator matrix elements. We show the necessity of introducing the appropriate Hankel-Riccati functions when the full Hamiltonian contains a centrifugal term in 1/R2 in order to reduce the computational time. The collisional system Si4++He is studied as a test case.

  9. Scaling for state-selective charge exchange due to collisions of multicharged ions with hydrogen

    NASA Astrophysics Data System (ADS)

    Jorge, A.; Illescas, Clara; Miraglia, J. E.; Gravielle, M. S.

    2015-12-01

    In this article we evaluate state-resolved charge exchange cross sections for Be{}4+, {{{B}}}5+, {{{C}}}6+, {{{N}}}7+, and {{{O}}}8+ projectiles colliding with atomic hydrogen employing two different methods: the classical trajectory Monte Carlo and the eikonal impulse approximations. These cross sections are used to extend previously derived scaling laws for n-, nl-, and nlm-distributions to highly excited final levels with 4≤slant n≤slant 9, covering energies in the range 50-2000 {{keV}}/ amu. Present total and partial capture cross sections are in agreement with available experimental and theoretical data for these collision systems. Besides, the proposed scaling rules are also verified by other theories, becoming a useful instrument for plasma research.

  10. Scaling for state-selective charge exchange due to collisions of multicharged ions with hydrogen

    NASA Astrophysics Data System (ADS)

    Jorge, A.; Illescas, Clara; Miraglia, J. E.; Gravielle, M. S.

    2014-12-01

    In this article we evaluate state-resolved charge exchange cross sections for Be{}4+, {{{B}}}5+, {{{C}}}6+, {{{N}}}7+, and {{{O}}}8+ projectiles colliding with atomic hydrogen employing two different methods: the classical trajectory Monte Carlo and the eikonal impulse approximations. These cross sections are used to extend previously derived scaling laws for n-, nl-, and nlm-distributions to highly excited final levels with 4≤slant n≤slant 9, covering energies in the range 50-2000 {{keV}}/ amu. Present total and partial capture cross sections are in agreement with available experimental and theoretical data for these collision systems. Besides, the proposed scaling rules are also verified by other theories, becoming a useful instrument for plasma research.

  11. Elasticity Modulation of Fibroblast-Derived Matrix for Endothelial Cell Vascular Morphogenesis and Mesenchymal Stem Cell Differentiation.

    PubMed

    Du, Ping; Suhaeri, Muhammad; Subbiah, Ramesh; Van, Se Young; Park, Jimin; Kim, Sang Heon; Park, Kwideok; Lee, Kangwon

    2016-03-01

    Biophysical properties of the microenvironment, including matrix elasticity and topography, are known to affect various cell behaviors; however, the specific role of each factor is unclear. In this study, fibroblast-derived matrix (FDM) was used as cell culture substrate and physically modified to investigate the influence of its biophysical property changes on human umbilical vein endothelial cells (HUVECs) and human mesenchymal stem cells (hMSCs) behavior in vitro. These FDMs were physically modified by simply storing them at different temperatures: the one stored at 4°C, maintained its original properties, was considered natural FDM, whereas the ones stored at -20°C or -80°C, exhibited a distinct surface morphology, were considered physically modified FDM. Physical modification induced matrix fiber rearrangement in FDM, forming different microstructures on the surface as characterized by focused ion beam (FIB)-cryoSEM. A significant increase of matrix elasticity was found with physically modified FDMs as determined by atomic force microscopy. HUVEC and hMSC behaviors on these natural and physically modified FDMs were observed and compared with each other and with gelatin-coated coverslips. HUVECs showed a similar adhesion level on these substrates at 3 h, but exhibited different proliferation rates and morphologies at 24 h; HUVECs on natural FDM proliferated relatively slower and assembled to capillary-like structures (CLSs). It is observed that HUVECs assembled to CLSs on natural FDMs are independent on the exogenous growth factors and yet dependent on nonmuscle myosin II activity. This result indicates the important role of matrix mechanical properties in regulating HUVECs vascular morphogenesis. As for hMSCs multilineage differentiation, adipogenesis is improved on natural FDM that with lower matrix elasticity, while osteogenesis is accelerated on physically modified FDMs that with higher matrix elasticity, these results further confirm the crucial

  12. An evaluation of the transition temperature range of super-elastic orthodontic NiTi springs using differential scanning calorimetry.

    PubMed

    Barwart, O; Rollinger, J M; Burger, A

    1999-10-01

    Differential scanning calorimetry (DSC) was used to determine the transition temperature ranges (TTR) of four types of super-elastic orthodontic nickel-titanium coil springs (Sentalloy). A knowledge of the TTR provides information on the temperature at which a NiTi wire or spring can assume superelastic properties and when this quality disappears. The spring types in this study can be distinguished from each other by their characteristic TTR during cooling and heating. For each tested spring type a characteristic TTR during heating (austenite transformation) and cooling (martensite transformation) was evaluated. The hysteresis of the transition temperature, found between cooling and heating, was 3.4-5.2 K. Depending on the spring type the austenite transformation started (As) at 9.7-17.1 degrees C and finished (Af) at 29.2-37 degrees C. The martensite transformation starting temperature (Ms) was evaluated at 32.6-25.4 degrees C, while Mf (martensite transformation finishing temperature) was 12.7-6.5 degrees C. The results show that the springs become super-elastic when the temperature increases and As is reached. They undergo a loss of super-elastic properties and a rapid decrease in force delivery when they are cooled to Mf. For the tested springs, Mf and As were found to be below room temperature. Thus, at room temperature and some degrees lower, all the tested springs exert super-elastic properties. For orthodontic treatment this means the maintenance of super-elastic behaviour, even when mouth temperature decreases to about room temperature as can occur, for example, during meals.

  13. Inelastic Scattering and Single and Double Charge Exchange Reactions Within the A=27 Isobaric Multiplet.

    NASA Astrophysics Data System (ADS)

    McKinzie, Matthew Gordon

    1995-01-01

    Angular distributions for the reactions ^{27}Al, ^{28 }Si(pi^{+/- },pi^{+/-} ) at T_pi = 180 MeV and an excitation function at theta_ {rm lab.} = 5^{ rm o} for the reaction ^{27}Al(pi^{+}, pi^{-})^{27}P were measured using the Energetic Pion Channel and Spectrometer at the Clinton P. Anderson Meson Physics Facility in Los Alamos, New Mexico. Angular distributions for the reaction ^{27}Al(n,p)^ {27}Mg were measured at T_ {rm N} = 198 MeV using the Medium Resolution Spectrometer at Canada's Tri-University Meson Facility in Vancouver, British Columbia. Multipole matrix elements were extracted in a macroscopic manner from the pion inelastic angular distributions using the distorted-wave impulse approximation and collective -model transition densities. Microscopic calculations of these extracted matrix elements and of the pion angular distributions were examined. Double charge exchange (DCX) excitation functions to the ^{27}P ground state and an excited state were measured at nine incident pion energies from T_pi = 100 to 293.4 MeV. The systematics of DCX excitation functions to low-lying states is reviewed in light of these data. Microscopic calculations of DCX for and near A = 27 are investigated. Double giant resonances in ^{27}P were observed at the three highest energies. The (n,p) charge exchange angular distributions were obtained for theta_{rm lab.} = 0^circ, 4^circ, 8^ circ, 12^circ, 18^circ and 24^ circ. The Gamow-Teller strength distribution was measured and compared to a microscopic calculation. The constant of proportionality between reduced transition probability and cross section (the unit cross section) was generalized and examined for configuration dependence. Data for higher spin-multipole isovector excitations are presented, including low-lying spin-isospin E2 strength and negative -parity giant resonances.

  14. Characteristics of low energy atom and molecule beams generated by the charge exchange reaction

    SciTech Connect

    Hara, Yasuhiro; Takashima, Seigo; Toyoda, Hirotaka; Sekine, Makoto; Hori, Masaru; Yamakawa, Koji; Den, Shoji

    2008-03-01

    A low energy NB source, which consisted of a surface wave plasma (SWP) source and two large diameter carbon electrodes, was developed for damageless etching of ultralarge-scale integrated devices. Ion beams were extracted from the SWP using two carbon electrodes, accelerated and injected to the process chamber, and then neutralized without energy loss by a charge exchange reaction. The energy distribution functions of an Ar ion beam and an Ar atom beam was observed using a quadrupole mass spectroscope equipped with an energy analyzer. The energy of the Ar ion beam and the Ar atom beam was controlled by the acceleration voltage. N{sub 2} ion and N ion beams were also extracted from a nitrogen plasma source. The intensity ratio of the N ion beam to the N{sub 2} ion beam was 5:9, indicating that N ions were efficiently generated in the nitrogen SWP. The N{sub 2} ion and N ion beams were changed to N{sub 2} molecule and N atom beams, respectively, through a charge exchange reaction without energy loss. The energy of these beams was controlled by the acceleration voltage and was in the region less of than 100 eV. When the acceleration voltage is higher than 40 V, not only the primary peaks due to the N{sub 2} ion beam or N ion beam were observed but also a low energy second peak was observed in the energy distribution. The energy of the low energy second peak was controlled by the acceleration voltage. It was concluded that the low energy second peak corresponds to the N{sub 2} molecule ion beam and the N ion beam, which is extracted from the second plasma generated in the space between the two carbon electrodes.

  15. Recent Advances in Computational Studies of Charge Exchange X-ray Emission

    NASA Astrophysics Data System (ADS)

    Cumbee, Renata

    2016-06-01

    Interest in astrophysical sources of charge exchange (CX) has grown since X-ray emission from comet Hyakutake was first observed, the origin of which is primarily due to CX processes between neutral species in the comet’s atmosphere and highly charged ions from the solar wind. More recent observations have shown that CX may have a significant contribution to the X-ray emission spectra of a wide variety of environments within our solar system including solar wind charge exchange (SWCX) with neutral gases in the heliosphere and in planetary atmospheres, as well as beyond the solar system in galaxy clusters, supernova remnants, and star forming galaxies.While the basic process of CX has been studied for many decades, the reliability of the existing data is not uniform, and the coverage of the astrophysically important projectile and target combinations and collisional velocities is insufficient. The need for reliable and robust CX X-ray emission models will only be amplified with the with the high resolution X-ray spectra expected from the soft X-ray imaging calorimeter spectrometer (SXS) onboard the Hitomi X-ray observatory. In this talk, I will discuss recent advances in theoretical CX cross sections and X-ray modeling with a focus on CX diagnostics. The need for experimental X-ray spectra and cross sections for benchmarking current theory will also be highlighted. This work was performed in collaboration with David Lyons, Patrick Mullen, David Schultz, Phillip Stancil, and Robin Shelton. Work at UGA was partially supported by NASA grant NNX09AC46G.

  16. Kinetic theory and atomic physics corrections for determination of ion velocities from charge-exchange spectroscopy

    NASA Astrophysics Data System (ADS)

    Muñoz Burgos, J. M.; Burrell, K. H.; Solomon, W. M.; Grierson, B. A.; Loch, S. D.; Ballance, C. P.; Chrystal, C.

    2013-09-01

    Charge-exchange spectroscopy is a powerful diagnostic tool for determining ion temperatures, densities and rotational velocities in tokamak plasmas. This technique depends on detailed understanding of the atomic physics processes that affect the measured apparent velocities with respect to the true ion rotational velocities. These atomic effects are mainly due to energy dependence of the charge-exchange cross-sections, and in the case of poloidal velocities, due to gyro-motion of the ion during the finite lifetime of the excited states. Accurate lifetimes are necessary for correct interpretation of measured poloidal velocities, specially for high density plasma regimes on machines such as ITER, where l-mixing effects must be taken into account. In this work, a full nl-resolved atomic collisional radiative model coupled with a full kinetic calculation that includes the effects of electric and magnetic fields on the ion gyro-motion is presented for the first time. The model directly calculates from atomic physics first principles the excited state lifetimes that are necessary to evaluate the gyro-orbit effects. It is shown that even for low density plasmas where l-mixing effects are unimportant and coronal conditions can be assumed, the nl-resolved model is necessary for an accurate description of the gyro-motion effects to determine poloidal velocities. This solution shows good agreement when compared to three QH-mode shots on DIII-D, which contain a wide range of toroidal velocities and high ion temperatures where greater atomic corrections are needed. The velocities obtained from the model are compared to experimental velocities determined from co- and counter-injection of neutral beams on DIII-D.

  17. Wall reflection modeling for charge exchange recombination spectroscopy (CXRS) measurements on Textor and ITER

    NASA Astrophysics Data System (ADS)

    Banerjee, Santanu; Vasu, P.; von Hellermann, M.; Jaspers, R. J. E.

    2010-12-01

    Contamination of optical signals by reflections from the tokamak vessel wall is a matter of great concern. For machines such as ITER and future reactors, where the vessel wall will be predominantly metallic, this is potentially a risk factor for quantitative optical emission spectroscopy. This is, in particular, the case when bremsstrahlung continuum radiation from the bulk plasma is used as a common reference light source for the cross-calibration of visible spectroscopy. In this paper the reflected contribution to the continuum level in Textor and ITER has been estimated for the detection channels meant for charge exchange recombination spectroscopy (CXRS). A model assuming diffuse reflection has been developed for the bremsstrahlung which is a much extended source. Based on this model, it is shown that in the case of ITER upper port 3, a wall with a moderate reflectivity of 20% leads to the wall reflected fraction being as high as 55-60% of the weak signals in the edge channels. In contrast, a complete bidirectional reflectance distribution function (BRDF) based model has been developed in order to estimate the reflections from more localized sources like the charge exchange (CX) emission from a neutral beam in tokamaks. The largest signal contamination of ~15% is seen in the core CX channels, where the true CX signal level is much lower than that in the edge channels. Similar values are obtained for Textor also. These results indicate that the contributions from wall reflections may be large enough to significantly distort the overall spectral features of CX data, warranting an analysis at different wavelengths.

  18. Production of high brightness H- beam by charge exchange of hydrogen atom beam in sodium jet

    SciTech Connect

    Davydenko, V.; Zelenski, A.; Ivanov, A.; Kolmogorov, A.

    2010-11-16

    Production of H{sup -} beam for accelerators applications by charge exchange of high brightness hydrogen neutral beam in a sodium jet cell is experimentally studied in joint BNL-BINP experiment. In the experiment, a hydrogen-neutral beam with 3-6 keV energy, equivalent current up to 5 A and 200 microsecond pulse duration is used. The atomic beam is produced by charge exchange of a proton beam in a pulsed hydrogen target. Formation of the proton beam is performed in an ion source by four-electrode multiaperture ion-optical system. To achieve small beam emittance, the apertures in the ion-optical system have small enough size, and the extraction of ions is carried out from the surface of plasma emitter with a low transverse ion temperature of {approx}0.2 eV formed as a result of plasma jet expansion from the arc plasma generator. Developed for the BNL optically pumped polarized ion source, the sodium jet target with recirculation and aperture diameter of 2 cm is used in the experiment. At the first stage of the experiment H{sup -} beam with 36 mA current, 5 keV energy and {approx}0.15 cm {center_dot} mrad normalized emittance was obtained. To increase H{sup -} beam current ballistically focused hydrogen neutral beam will be applied. The effects of H{sup -} beam space-charge and sodium-jet stability will be studied to determine the basic limitations of this approach.

  19. What can be Learned from X-ray Spectroscopy Concerning Hot Gas in Local Bubble and Charge Exchange Processes?

    NASA Technical Reports Server (NTRS)

    Snowden, Steve

    2007-01-01

    What can be learned from x-ray spectroscopy in observing hot gas in local bubble and charge exchange processes depends on spectral resolution, instrumental grasp, instrumental energy band, signal-to-nose, field of view, angular resolution and observatory location. Early attempts at x-ray spectroscopy include ROSAT; more recently, astronomers have used diffuse x-ray spectrometers, XMM Newton, sounding rocket calorimeters, and Suzaku. Future observations are expected with calorimeters on the Spectrum Roentgen Gamma mission, and the Solar Wind Charge Exchange (SWCX). The Geospheric SWCX may provide remote sensing of the solar wind and magnetosheath and remote observations of solar CMEs moving outward from the sun.

  20. The Measurement of Pion Double Charge Exchange on CARBON-13, CARBON-14, MAGNESIUM-26 and IRON-56.

    NASA Astrophysics Data System (ADS)

    Seidl, Peter Anthony

    Cross sections for the ('13,14)C,('26)Mg,('56)Fe((pi)('+),(pi)(' -))('13,14)O,('26)Si,('56)Ni reactions were measured with the Energetic Pion Channel and Spectrometer at the Clinton P. Anderson Meson Physics Facility for 120 (LESSTHEQ) T(,(pi)) (LESSTHEQ) 292 MeV and 0 (LESSTHEQ) (theta) (LESSTHEQ) 50. The double isobaric analog states (DIAS) were of primary interest, and in addition, cross sections for transitions to ('14)O(0('+), 5.92 MeV), ('14)O(2('+), 7.77 MeV), ('56)Ni(gs), ('13)O(gs), and ('13)O(4.21 MeV) are presented. The ('13)O(4.21 MeV) state is postulated to have J('(pi)) = 1/2('-). The data are compared to previously measured double-charge -exchange cross sections on other nuclei, and the systematics of double charge exchange on T (GREATERTHEQ) 1 target nuclei leading to DIAS are studied. Near the (DELTA)(,33) resonance, cross section for the DIAS transitions are in disagreement with calculations in which the reaction is treated as sequential charge exchange through the free pion-nucleon amplitude, while for T(,(pi)) > 200 MeV the anomalous features of the 164 MeV data are not apparent. This is evidence for significant higher order contributions to the double-charge -exchange amplitude near the resonance energy. Two theoretical approaches that include two nucleon processes are applied to the DIAS data.

  1. A simple elastic membrane-based microfluidic chip for the proliferation and differentiation of mesenchymal stem cells under tensile stress.

    PubMed

    Gao, Xinghua; Zhang, Xu; Tong, Huiyu; Lin, Bingcheng; Qin, Jianhua

    2011-11-01

    This work presents a simple membrane-based microfluidic chip for the investigation of proliferation and differentiation of mesenchymal stem cells (MSCs) under mechanical stimuli. The cyclic tensile stress was generated by the deformation of elastic PDMS membrane sandwiched between the two layer microfluidic chip via actuated negative pressure, and the cultured MSCs on membrane were subjected to different orders of tensile stress. The results suggest that mechanical stimuli are attributed to the different phenomena of MSCs in cell proliferation and differentiation. The higher tensile stress (>3.5) promoted obvious proliferation, osteogenesis and reduced adipogenesis in MSCs, indicating the possible regulative role of tensile stress in modifying the osteogenesis/adipogenesis balance in the development of tissue organ. PMID:22072525

  2. Co-effects of matrix low elasticity and aligned topography on stem cell neurogenic differentiation and rapid neurite outgrowth

    NASA Astrophysics Data System (ADS)

    Yao, Shenglian; Liu, Xi; Yu, Shukui; Wang, Xiumei; Zhang, Shuming; Wu, Qiong; Sun, Xiaodan; Mao, Haiquan

    2016-05-01

    The development of novel biomaterials that deliver precise regulatory signals to direct stem cell fate for nerve regeneration is the focus of current intensive research efforts. In this study, a hierarchically aligned fibrillar fibrin hydrogel (AFG) that was fabricated through electrospinning and the concurrent molecular self-assembly process mimics both the soft and oriented features of nerve tissue, thus providing hybrid biophysical cues to instruct cell behavior in vitro and in vivo. The electrospun hydrogels were examined by scanning electron microscopy (SEM), polarized light microscopy, small angle X-ray scattering assay and atomic force microscopy (AFM), showing a hierarchically linear-ordered structure from the nanoscale to the macroscale with a soft elastic character (elasticity ~1 kPa). We found that this low elasticity and aligned topography of AFG exhibit co-effects on promoting the neurogenic differentiation of human umbilical cord mesenchymal stem cells (hUMSCs) in comparison to random fibrin hydrogel (RFG) and tissue culture plate (TCP) control after two week cell culture in growth medium lacking supplementation with soluble neurogenic induction factors. In addition, AFG also induces dorsal root ganglion (DRG) neurons to rapidly project numerous long neurite outgrowths longitudinally along the AFG fibers for a total neurite extension distance of 1.96 mm in three days in the absence of neurotrophic factor supplementation. Moreover, the AFG implanted in a rat T9 dorsal hemisection spinal cord injury model was found to promote endogenous neural cell fast migration and axonal invasion along AFG fibers, resulting in aligned tissue cables in vivo. Our results suggest that matrix stiffness and aligned topography may instruct stem cell neurogenic differentiation and rapid neurite outgrowth, providing great promise for biomaterial design for applications in nerve regeneration.The development of novel biomaterials that deliver precise regulatory signals to

  3. Co-effects of matrix low elasticity and aligned topography on stem cell neurogenic differentiation and rapid neurite outgrowth.

    PubMed

    Yao, Shenglian; Liu, Xi; Yu, Shukui; Wang, Xiumei; Zhang, Shuming; Wu, Qiong; Sun, Xiaodan; Mao, Haiquan

    2016-05-21

    The development of novel biomaterials that deliver precise regulatory signals to direct stem cell fate for nerve regeneration is the focus of current intensive research efforts. In this study, a hierarchically aligned fibrillar fibrin hydrogel (AFG) that was fabricated through electrospinning and the concurrent molecular self-assembly process mimics both the soft and oriented features of nerve tissue, thus providing hybrid biophysical cues to instruct cell behavior in vitro and in vivo. The electrospun hydrogels were examined by scanning electron microscopy (SEM), polarized light microscopy, small angle X-ray scattering assay and atomic force microscopy (AFM), showing a hierarchically linear-ordered structure from the nanoscale to the macroscale with a soft elastic character (elasticity ∼1 kPa). We found that this low elasticity and aligned topography of AFG exhibit co-effects on promoting the neurogenic differentiation of human umbilical cord mesenchymal stem cells (hUMSCs) in comparison to random fibrin hydrogel (RFG) and tissue culture plate (TCP) control after two week cell culture in growth medium lacking supplementation with soluble neurogenic induction factors. In addition, AFG also induces dorsal root ganglion (DRG) neurons to rapidly project numerous long neurite outgrowths longitudinally along the AFG fibers for a total neurite extension distance of 1.96 mm in three days in the absence of neurotrophic factor supplementation. Moreover, the AFG implanted in a rat T9 dorsal hemisection spinal cord injury model was found to promote endogenous neural cell fast migration and axonal invasion along AFG fibers, resulting in aligned tissue cables in vivo. Our results suggest that matrix stiffness and aligned topography may instruct stem cell neurogenic differentiation and rapid neurite outgrowth, providing great promise for biomaterial design for applications in nerve regeneration. PMID:27124547

  4. CAN CHARGE EXCHANGE EXPLAIN ANOMALOUS SOFT X-RAY EMISSION IN THE CYGNUS LOOP?

    SciTech Connect

    Cumbee, R. S.; Henley, D. B.; Stancil, P. C.; Shelton, R. L.; Nolte, J. L.; Wu, Y.; Schultz, D. R.

    2014-06-01

    Recent X-ray studies have shown that supernova shock models are unable to satisfactorily explain X-ray emission in the rim of the Cygnus Loop. In an attempt to account for this ''anomalously'' enhanced X-ray flux, we fit the region with a model including theoretical charge exchange (CX) data along with shock and background X-ray models. The model includes the CX collisions of O{sup 8} {sup +}, O{sup 7} {sup +}, N{sup 7} {sup +}, N{sup 6} {sup +}, C{sup 6} {sup +}, and C{sup 5} {sup +} with H with an energy of 1 keV u{sup –1} (438 km s{sup –1}). The observations reveal a strong emission feature near 0.7 keV that cannot fully be accounted for by a shock model, nor the current CX data. Inclusion of CX, specifically O{sup 7} {sup +} + H, does provide for a statistically significant improvement over a pure shock model.

  5. Temperatures of individual ion species and heating due to charge exchange in the ionosphere of Venus

    NASA Technical Reports Server (NTRS)

    Kim, Jhoon; Nagy, Andrew F.; Cravens, Thomas E.; Shinagawa, Hiroyuki

    1990-01-01

    The coupled electron and multispecies ion energy equations were solved for daytime conditions in the Venus ionosphere. The heating rates due to charge exchange between hot oxygen atoms and thermal oxygen ions were calculated and incorporated into the energy equations. The combination of the traditional EUV heating and this hot oxygen energy source leads to calculated electron and individual ion temperatures significantly lower than the measured values during solar cycle maximum conditions. Calculations were also carried out for solar cycle minimum conditions, which led to considerably lower temperatures; no data are available which would allow direct comparisons of these results with measurements. In order to obtain calculated temperature values consistent with the observed ones, for solar cycle maximum conditions, topside heat inflows into the ion and electron gases have to be introduced or the thermal conductivity must be reduced by considering the effect of steady and fluctuating magnetic fields, as was done in previous studies. The addition of hot oxygen heating leads to minor increases in the calculated ion temperatures except for the case of reduced thermal conductivities. Separate temperatures were calculated for each ion species for a number of different conditions and in general the differences were found to be relatively small.

  6. The velocity dependence of X-ray emission due to Charge Exchange in the Cygnus Loop

    NASA Astrophysics Data System (ADS)

    Cumbee, Renata; Lyons, David; Mullen, Patrick Dean; Shelton, Robin L.; Stancil, Phillip C.; Schultz, David R.

    2016-01-01

    The fundamental collisional process of charge exchange (CX) has been been established as a primary source of X-ray emission from the heliosphere [1], planetary exospheres [2], and supernova remnants [3,4]. In this process, X-ray emission results from the capture of an electron by a highly charged ion from a neutral atom or molecule, to form a highly-excited, high charge state ion. As the captured electron cascades down to the lowest energy level, photons are emitted, including X-rays.To provide reliable CX-induced X-ray spectral models to realistically simulate these environments, line ratios and spectra are computed using theoretical CX cross-sections obtained with the multi-channel Landau-Zener, atomic-orbital close-coupling, and classical-trajectory Monte Carlo methods for various collisional velocities relevant to astrophysics for collisions of bare and H-like C to Al ions with H, He, and H2. Using these line ratios, XSPEC models of CX emission in the northeast rim of the Cygnus Loop supernova remnant will be shown as an example with ion velocity dependence.[1] Henley, D. B. & Shelton, R. L. 2010, ApJSS, 187, 388[2] Dennerl, K. et al. 2002, A&A 386, 319[3] Katsuda, S. et al. 2011, ApJ 730 24[4] Cumbee, R. S. et al. 2014, ApJ 787 L31This work was partially supported by NASA grant NNX09AC46G.

  7. Status of Charge Exchange Cross Section Measurements for Highly Charged Ions on Atomic Hydrogen

    NASA Astrophysics Data System (ADS)

    Draganic, I. N.; Havener, C. C.; Schultz, D. R.; Seely, D. G.; Schultz, P. C.

    2011-05-01

    Total cross sections of charge exchange (CX) for C5+, N6+, and O7+ ions on ground state atomic hydrogen are measured in an extended collision energy range of 1 - 20,000 eV/u. Absolute CX measurements are performed using an improved merged-beams technique with intense highly charged ion beams extracted from a 14.5 GHz ECR ion source mounted on a high voltage platform. In order to improve the problematic H+ signal collection for these exoergic CX collisions at low relative energies, a new double focusing electrostatic analyzer was installed. Experimental CX data are in good agreement with all previous H-oven relative measurements at higher collision energies. We compare our results with the most recent molecular orbital close-coupling (MOCC) and atomic orbital close-coupling (AOCC) theoretical calculations. Work supported by the NASA Solar & Heliospheric Physics Program NNH07ZDA001N, the Office of Fusion Energy Sciences and the Division of Chemical Sciences, Geosciences, and Biosciences, and the Office of Basic Energy Sciences of the U.S. DoE.

  8. Solar Wind Charge Exchange Studies Of Highly Charged Ions On Atomic Hydrogen

    SciTech Connect

    Draganic, I. N.; Havener, C. C.; Seely, D. G.; McCammon, D.

    2011-06-01

    Accurate studies of low-energy charge exchange (CX) are critical to understanding underlying soft X-ray radiation processes in the interaction of highly charged ions from the solar wind with the neutral atoms and molecules in the heliosphere, cometary comas, planetary atmospheres, interstellar winds, etc.. Particularly important are the CX cross sections for bare, H-like, and He-like ions of C, N, O and Ne, which are the dominant charge states for these heavier elements in the solar wind. Absolute total cross sections for single electron capture by H-like ions of C, N, O and fully-stripped O ions from atomic hydrogen have been measured in an expanded range of relative collision energies (5 eV/u-20 keV/u) and compared to previous H-oven measurements. The present measurements are performed using a merged-beams technique with intense highly charged ion beams extracted from a 14.5 GHz ECR ion source installed on a high voltage platform at the Oak Ridge National Laboratory. For the collision energy range of 0.3 keV/u-3.3 keV/u, which corresponds to typical ion velocities in the solar wind, the new measurements are in good agreement with previous H-oven measurements. The experimental results are discussed in detail and compared with theoretical calculations where available.

  9. Solar Wind Charge Exchange Studies of Highly Charged Ions on Atomic Hydrogen

    SciTech Connect

    Draganic, Ilija N; Seely, D. G.; McCammon, D; Havener, Charles C

    2011-01-01

    Accurate studies of low energy charge exchange (CX) are critical to understanding underlying soft X ray radiation processes in the interaction of highly charged ions from the solar wind with the neutral atoms and molecules in the heliosphere, cometary comas, planetary atmospheres, interstellar winds, etc.. Particularly important are the CX cross sections for bare, H like, and He like ions of C, N, O and Ne, which are the dominant charge states for these heavier elements in the solar wind. Absolute total cross sections for single electron capture by H like ions of C, N, O and fully stripped O ions from atomic hydrogen have been measured in an expanded range of relative collision energies (5 eV u 20 keV u) and compared to previous H oven measurements. The present measurements are performed using a merged beams technique with intense highly charged ion beams extracted from a 14.5 GHz ECR ion source installed on a high voltage platform at the Oak Ridge National Laboratory. For the collision energy range of 0.3 keV u 3.3 keV u, which corresponds to typical ion velocities in the solar wind, the new measurements are in good agreement with previous H oven measurements. The experimental results are discussed in detail and compared with theoretical calculations where available.

  10. Possible Charge Exchange X-Ray Emission from the Cygnus Loop detected with Suzaku

    NASA Astrophysics Data System (ADS)

    Katsuda, Satoru; Tsunemi, Hiroshi; Mori, Koji; Uchida, Hiroyuki; Kosugi, Hiroko; Kimura, Masashi; Petre, Robert; Hwang, Una; Hewitt, John

    We present results of a spatially-resolved X-ray spectral analysis of nearly the entire rim of the Cygnus Loop using Suzaku (21 pointings) and XMM-Newton (1 pointing). We find that some of the spectra show a bump at ˜0.7 keV as a "shoulder" of the lines at ˜0.66 keV which is a combination of O H Lyα and O Heβ. The regions showing the "shoulder" is confined within narrow (< a few arcmin) regions behind the shock at position angles of 0-40, 110-160, and 270-330 degrees measured from north over east. Around the rim, the position angles where the X-ray excess is present correspond to relatively weak radio emission as well as optical emission from non-radiative Hα filaments. While other possibilities (e.g., Fe L emission) cannot be fully excluded, these correlations lead us to consider that the "shoulder" may be O Heγ + δ + etc lines produced by charge exchange between H-like O ions and neutral H. Whatever its origin, the "shoulder" significantly affects the spectral analysis; the best-fit parameters strongly depend on whether or not we include the "shoulder" in the spectral fitting. We will discuss this issue in terms of our previous results of our spectral analysis for the rim regions.

  11. Suzaku and XMM-Newton observations of the North Polar Spur: Charge exchange or ISM absorption?

    NASA Astrophysics Data System (ADS)

    Gu, Liyi; Mao, Junjie; Costantini, Elisa; Kaastra, Jelle

    2016-10-01

    By revisiting the Suzaku and XMM-Newton data of the North Polar Spur, we discovered that the spectra are inconsistent with the traditional model consisting of pure thermal emission and neutral absorption. The most prominent discrepancies are the enhanced O vii and Ne ix forbidden-to-resonance ratios, and a high O viii Lyβ line relative to other Lyman series. A collisionally ionized absorption model can naturally explain both features, while a charge exchange component can only account for the former. By including the additional ionized absorption, the plasma in the North Polar Spur can be described by a single-phase collisional ionization equilibrium (CIE) component with a temperature of 0.25 keV, and nitrogen, oxygen, neon, magnesium, and iron abundances of 0.4-0.8 solar. The abundance pattern of the North Polar Spur is well in line with those of the Galactic halo stars. The high nitrogen-to-oxygen ratio reported in previous studies can be migrated to the large transmission of the O viii Lyα line. The ionized absorber is characterized by a balance temperature of 0.17-0.20 keV and a column density of 3-5 × 1019 cm-2. Based on the derived abundances and absorption, we speculate that the North Polar Spur is a structure in the Galactic halo, so that the emission is mostly absorbed by the Galactic interstellar medium in the line of sight.

  12. Feasibility of non-thermal helium measurements with charge exchange spectroscopy on ITER

    NASA Astrophysics Data System (ADS)

    Kappatou, A.; Delabie, E.; Jaspers, R. J. E.; von Hellermann, M. G.

    2012-04-01

    The use of active charge exchange recombination spectroscopy (CXRS) as a diagnostic for fusion-produced alpha particles on ITER is constrained by the signal-to-noise ratio, which is determined by the intensity of the line of interest, the optical throughput of the diagnostic, the neutral beam penetration, and the intensity of bremsstrahlung radiation. The CX spectral line for fast ions has been modelled together with the expected background emission and we present the signal-to-noise ratios calculated as a function of the diagnostic design parameters. Combining the CXRS data from both the heating and the diagnostic neutral beams on ITER, information on fast ions with energies up to 1 MeV can be obtained for the parameters of the ITER core CXRS diagnostic design. To achieve this, energy binning of the signal is used (100 keV bins or larger), in order to improve the signal-to-noise ratio, with a time resolution of 2 s. The time resolution of the measurement can be improved using a higher throughput spectrometer, but this is ultimately limited by the amount of light from the neutral beam that can be collected. Despite the challenges and the fact that the results are not as optimistic as previously assumed, it is concluded that useful information on fast helium density profiles can be obtained using CXRS on ITER.

  13. X-ray emission from charge exchange in the Cygnus Loop SNR

    NASA Astrophysics Data System (ADS)

    Roberts, Shawn R.; Wang, Q. Daniel

    2015-05-01

    The Cygnus Loop has been the focus of substantial debate concerning the contribution of charge exchange (CX) to supernova remnant (SNR) X-ray emission. We take advantage of a distinct feature of CX, enhanced Kα forbidden line emission, and employ the energy centroid of the O VII Kα triplet as a diagnostic. Based on X-ray spectra extracted from an extensive set of Suzaku observations, we measure the energy centroid shifts of the triplet on and off the shock rim of the remnant. We find that enhanced forbidden to resonance line emission exists throughout much of the rim and this enhancement azimuthally correlates with non-radiative Hα filaments, a tracer of strong neutral-plasma interaction in the optical. We also show that alternative mechanisms cannot explain the observed enhancement. These results demonstrate the need to model the CX contribution to the X-ray emission of SNRs, particularly for shocks propagating in a partially neutral medium. Such modelling may be critically important to the correct measurements of the ionization, thermal, and chemical properties of SNRs.

  14. Unstable ring-shaped ion distribution functions induced by charge-exchange collisions

    NASA Astrophysics Data System (ADS)

    Miloch, W. J.; Pécseli, H. L.; Trulsen, J. K.

    2013-12-01

    The stability of ion velocity distributions in magnetized plasmas is studied under conditions where the plasma has an E0 × B/B2-drift with respect to a neutral background. Charge-exchange collisions can give rise to velocity distributions having the form of a ring or a loss-cone that can become linearly unstable. Sometimes the distributions have distorted forms and a stability analysis is not straightforward. Numerical simulations offer the most convenient method of a stability analysis in such cases. By numerical simulations using a particle-in-cell code that includes collisional interactions we demonstrate the formation of such velocity distributions and study the instabilities associated with them. We observe the saturation of the linear instability by quasi-linear velocity space diffusion. The parameter dependence of the instability conditions is illustrated by examples. The results are relevant for explaining some of the low frequency oscillations observed in the lower parts of the Earth's ionosphere (E- and F-regions), where collisions with neutrals are abundant. The results are important for laboratory experiments as well.

  15. The loss rates of O{sup +} in the inner magnetosphere caused by both magnetic field line curvature scattering and charge exchange reactions

    SciTech Connect

    Ji, Y.; Shen, C.

    2014-03-15

    With consideration of magnetic field line curvature (FLC) pitch angle scattering and charge exchange reactions, the O{sup +} (>300 keV) in the inner magnetosphere loss rates are investigated by using an eigenfunction analysis. The FLC scattering provides a mechanism for the ring current O{sup +} to enter the loss cone and influence the loss rates caused by charge exchange reactions. Assuming that the pitch angle change is small for each scattering event, the diffusion equation including a charge exchange term is constructed and solved; the eigenvalues of the equation are identified. The resultant loss rates of O{sup +} are approximately equal to the linear superposition of the loss rate without considering the charge exchange reactions and the loss rate associated with charge exchange reactions alone. The loss time is consistent with the observations from the early recovery phases of magnetic storms.

  16. Proton Nucleus Elastic Scattering Data.

    1993-08-18

    Version 00 The Proton Nucleus Elastic Scattering Data file PNESD contains the numerical data and the related bibliography for the differential elastic cross sections, polarization and integral nonelastic cross sections for elastic proton-nucleus scattering.

  17. The Differential Association of Kidney Dysfunction With Small and Large Arterial Elasticity

    PubMed Central

    Katz, Ronit; Madero, Magdalena; Sarnak, Mark; Kramer, Holly; Criqui, Michael H.; Shlipak, Michael G.

    2009-01-01

    Vascular remodeling may be a mechanism linking chronic kidney disease to cardiovascular disease. Whether early kidney dysfunction is associated with small and large arterial remodeling is not well understood. Using multivariable linear regression, back-transforming beta-coefficients to relative difference, the authors studied the association of cystatin C, creatinine-based estimated glomerular filtration rate (GFR), and albuminuria with small (SAE) and large (LAE) arterial elasticity and aortic distensibility among 6,282 participants in the Multiethnic Study of Atherosclerosis at baseline (2000–2002). Compared with the lowest quintile, higher quintiles of cystatin C were incrementally associated with lower SAE: third quintile relative difference = −5% (95% confidence interval (CI): −8, −2); fourth quintile relative difference = −10% (95% CI: −13, −8); and highest quintile relative difference = −16% (95% CI: −20, −12). By use of creatinine, the association was observed only among those with chronic kidney disease (estimated GFR, <60 mL/minute/1.73 m2): relative difference = −9% (95% CI: −13, −4). Albuminuria was significantly associated with lower SAE: relative difference = −6% (95% CI: −10, −1). Cystatin C was associated with lower LAE only at the highest quintile (relative difference = −3%, 95% CI: −6, 0) compared with the lowest quintile. By use of creatinine, chronic kidney disease was not independently associated with LAE (P = 0.912). Cystatin C, estimated GFR, and albuminuria were not associated with aortic distensibility (P = 0.26, 0.48, 0.45). Early kidney dysfunction is significantly associated with decreased arterial elasticity in smaller arteries and, to a lesser degree, in larger arteries. PMID:19131564

  18. Linking cell shape, elasticity and fate: in vitro re-differentiation of chondrocytes

    NASA Astrophysics Data System (ADS)

    Yuan, Xiaofei; Chim, Yahua; Yin, Huabing

    2014-02-01

    Autologous chondrocyte transplantation (ACT) has become a promising method for repairing large articular defects. However, dedifferentiation of chondrocytes during cell expansion remains a major limitation for ACT procedures. In this study, we explore the potential of confining cell shape for re-differentiation of dedifferentiated bovine chondrocytes. A novel culture system, combining 2D micropatterning with 3D matrix formation, was developed to control and maintain individual chondrocyte's shape. Both collagen II synthesis and the mechanical properties of cells were monitored during re-differentiation. We show that a spherical morphology without cell spreading plays a limited role in induction of re-differentiation. Instead, isolated, dedifferentiated chondrocytes partially regain chondrogenic properties if they have an appropriate cell shape and limited spreading.

  19. Elastic positron scattering by C{sub 2}H{sub 2}: Differential cross sections and virtual state formation

    SciTech Connect

    Carvalho, Claudia R.C. de; Varella, Marcio T. do N; Lima, Marco A.P.; Silva, Euclimar P. da

    2003-12-01

    We present calculated elastic differential cross sections for positron-acetylene scattering, obtained by using the Schwinger multichannel method. Our results are in very good agreement with quasielastic experimental data of Kauppila et al. [Nucl. Instrum. Meth. Phys. Res. B 192, 162 (2002)]. We also discuss the existence of a virtual state (zero-energy resonance) in e{sup +}-C{sub 2}H{sub 2} collisions, based on the behavior of the integral cross section and of the s-wave phase shift. As expected the fixed-nuclei cross section and annihilation parameter (Z{sub eff}) present the same energy dependence at very low impact energies. As the virtual state energy approaches zero, the magnitude of both cross section and Z{sub eff} are extremely enhanced (at zero impact energy). The possibility of shifting from a low-lying virtual state to a shallow bound state is not expected to significantly affect room-temperature annihilation rates.

  20. Spectral Modeling of the Charge-exchange X-Ray Emission from M82

    NASA Astrophysics Data System (ADS)

    Zhang, Shuinai; Wang, Q. Daniel; Ji, Li; Smith, Randall K.; Foster, Adam R.; Zhou, Xin

    2014-10-01

    It has been proposed that the charge-exchange (CX) process at the interface between hot and cool interstellar gases could contribute significantly to the observed soft X-ray emission in star-forming galaxies. We analyze the XMM-Newton/reflection grating spectrometer (RGS) spectrum of M82 using a newly developed CX model combined with a single-temperature thermal plasma to characterize the volume-filling hot gas. The CX process is largely responsible for not only the strongly enhanced forbidden lines of the Kα triplets of various He-like ions but also good fractions of the Lyα transitions of C VI (~87%), O VIII, and N VII (gsim50%) as well. In total about a quarter of the X-ray flux in the RGS 6-30 Å band originates in the CX. We infer an ion incident rate of 3 × 1051 s-1 undergoing CX at the hot and cool gas interface and an effective area of the interface of ~2 × 1045 cm2 that is one order of magnitude larger than the cross section of the global biconic outflow. With the CX contribution accounted for, the best-fit temperature of the hot gas is 0.6 keV, and the metal abundances are approximately solar. We further show that the same CX/thermal plasma model also gives an excellent description of the EPIC-pn spectrum of the outflow Cap, projected at 11.6 kpc away from the galactic disk of M82. This analysis demonstrates that the CX is potentially an important contributor to the X-ray emission from starburst galaxies and also an invaluable tool to probe the interface astrophysics.

  1. Spectral modeling of the charge-exchange X-ray emission from M82

    SciTech Connect

    Zhang, Shuinai; Ji, Li; Zhou, Xin; Wang, Q. Daniel; Smith, Randall K.; Foster, Adam R.

    2014-10-10

    It has been proposed that the charge-exchange (CX) process at the interface between hot and cool interstellar gases could contribute significantly to the observed soft X-ray emission in star-forming galaxies. We analyze the XMM-Newton/reflection grating spectrometer (RGS) spectrum of M82 using a newly developed CX model combined with a single-temperature thermal plasma to characterize the volume-filling hot gas. The CX process is largely responsible for not only the strongly enhanced forbidden lines of the Kα triplets of various He-like ions but also good fractions of the Lyα transitions of C VI (∼87%), O VIII, and N VII (≳50%) as well. In total about a quarter of the X-ray flux in the RGS 6-30 Å band originates in the CX. We infer an ion incident rate of 3 × 10{sup 51} s{sup –1} undergoing CX at the hot and cool gas interface and an effective area of the interface of ∼2 × 10{sup 45} cm{sup 2} that is one order of magnitude larger than the cross section of the global biconic outflow. With the CX contribution accounted for, the best-fit temperature of the hot gas is 0.6 keV, and the metal abundances are approximately solar. We further show that the same CX/thermal plasma model also gives an excellent description of the EPIC-pn spectrum of the outflow Cap, projected at 11.6 kpc away from the galactic disk of M82. This analysis demonstrates that the CX is potentially an important contributor to the X-ray emission from starburst galaxies and also an invaluable tool to probe the interface astrophysics.

  2. Observation and modeling of geocoronal charge exchange X-ray emission during solar wind gusts

    SciTech Connect

    Wargelin, B. J.; Kornbleuth, M.; Juda, M.; Martin, P. L.

    2014-11-20

    Solar wind charge exchange (SWCX) X-rays are emitted when highly charged solar wind ions such as O{sup 7{sup +}} collide with neutral gas, including the Earth's tenuous outer atmosphere (exosphere or geocorona) and hydrogen and helium from the local interstellar medium drifting through the heliosphere. This geocoronal and heliospheric emission comprises a significant and varying fraction of the soft X-ray background (SXRB) and is seen in every X-ray observation, with the intensity dependent on solar wind conditions and observation geometry. Under the right conditions, geocoronal emission can increase the apparent SXRB by roughly an order of magnitude for an hour or more. In this work, we study a dozen occasions when the near-Earth solar wind flux was exceptionally high. These gusts of wind lead to abrupt changes in SWCX X-ray emission around Earth, which may or may not be seen by X-ray observatories depending on their line of sight. Using detailed three-dimensional magnetohydrodynamical simulations of the solar wind's interaction with the Earth's magnetosphere, and element abundances and ionization states measured by ACE, we model the time-dependent brightness of major geocoronal SWCX emission lines during those gusts and compare with changes in the X-ray background measured by the Chandra X-ray Observatory. We find reasonably good agreement between model and observation, with measured geocoronal line brightnesses averaged over 1 hr of up to 136 photons s{sup –1} cm{sup –2} sr{sup –1} in the O VII Kα triplet around 564 eV.

  3. Upper-limit charge exchange cross sections for mercury (plus) on molybdenum and cesium (plus) on aluminum

    NASA Technical Reports Server (NTRS)

    Dugan, J. V., Jr.

    1972-01-01

    Upper-limit charge exchange cross sections are calculated for Hg(+) on Mo and Cs(+) on Al. The cross sections are calculated from the polarization interaction at low ion energies (1 to 500 eV) and by assuming favorable curve crossings with a hard-core reaction radius at higher energies (500 eV to 10 keV). The cross sections for Hg(+) on Mo becomes greater than corresponding Hg Hg(+) resonance values at ion energies below 2 eV, whereas the Cs(+) Al values remain considerably lower than the Cs(+)Cs resonance value at all ion energies. It is also shown that charge exchange of slow Hg(+) with Mo may be important for spacecraft with electron bombardment thrusters.

  4. Method to obtain absolute impurity density profiles combining charge exchange and beam emission spectroscopy without absolute intensity calibrationa)

    NASA Astrophysics Data System (ADS)

    Kappatou, A.; Jaspers, R. J. E.; Delabie, E.; Marchuk, O.; Biel, W.; Jakobs, M. A.

    2012-10-01

    Investigation of impurity transport properties in tokamak plasmas is essential and a diagnostic that can provide information on the impurity content is required. Combining charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES), absolute radial profiles of impurity densities can be obtained from the CXRS and BES intensities, electron density and CXRS and BES emission rates, without requiring any absolute calibration of the spectra. The technique is demonstrated here with absolute impurity density radial profiles obtained in TEXTOR plasmas, using a high efficiency charge exchange spectrometer with high etendue, that measures the CXRS and BES spectra along the same lines-of-sight, offering an additional advantage for the determination of absolute impurity densities.

  5. The TFTR E Parallel B Spectrometer for Mass and Energy Resolved Multi-Ion Charge Exchange Diagnostics

    SciTech Connect

    A.L. Roquemore; S.S. Medley

    1998-01-01

    The Charge Exchange Neutral Analyzer diagnostic for the Tokamak Fusion Test Reactor was designed to measure the energy distributions of both the thermal ions and the supra thermal populations arising from neutral-beam injection and ion cyclotron radio-frequency heating. These measurements yield the plasma ion temperature, as well as several other plasma parameters necessary to provide an understanding of the plasma condition and the performance of the auxiliary heating methods. For this application, a novel charge-exchange spectrometer using a dee-shaped region of parallel electric and magnetic fields was developed at the Princeton Plasma Physics Laboratory. The design and performance of this spectrometer is described in detail, including the effects of exposure of the microchannel plate detector to magnetic fields, neutrons, and tritium.

  6. Charge-exchange coupling between pickup ions across the heliopause and its effect on energetic neutral hydrogen flux

    SciTech Connect

    Zirnstein, E. J.; Heerikhuisen, J.; Zank, G. P.; Pogorelov, N. V.; McComas, D. J.; Desai, M. I.

    2014-03-10

    Pickup ions (PUIs) appear to play an integral role in the multi-component nature of the plasma in the interaction between the solar wind (SW) and local interstellar medium (LISM). Three-dimensional (3D) MHD simulations with a kinetic treatment for neutrals and PUIs are currently still not viable. In light of recent energetic neutral atom (ENA) observations by the Interstellar Boundary EXplorer, the purpose of this paper is to illustrate the complex coupling between PUIs across the heliopause (HP) as facilitated by ENAs using estimates of PUI properties extracted from a 3D MHD simulation of the SW-LISM interaction with kinetic neutrals. First, we improve upon the multi-component treatment of the inner heliosheath (IHS) plasma from Zank et al. by including the extinction of PUIs through charge-exchange. We find a significant amount of energy is transferred away from hot, termination shock-processed PUIs into a colder, 'freshly injected' PUI population. Second, we extend the multi-component approach to estimate ENA flux from the outer heliosheath (OHS), formed from charge-exchange between interstellar hydrogen atoms and energetic PUIs. These PUIs are formed from ENAs in the IHS that crossed the HP and experienced charge-exchange. Our estimates, based on plasma-neutral simulations of the SW-LISM interaction and a post-processing analysis of ENAs and PUIs, suggest the majority of flux visible at 1 AU from the front of the heliosphere, between ∼0.02 and 10 keV, originates from OHS PUIs, indicating strong coupling between the IHS and OHS plasmas through charge-exchange.

  7. Charge-exchange Coupling between Pickup Ions across the Heliopause and its Effect on Energetic Neutral Hydrogen Flux

    NASA Astrophysics Data System (ADS)

    Zirnstein, E. J.; Heerikhuisen, J.; Zank, G. P.; Pogorelov, N. V.; McComas, D. J.; Desai, M. I.

    2014-03-01

    Pickup ions (PUIs) appear to play an integral role in the multi-component nature of the plasma in the interaction between the solar wind (SW) and local interstellar medium (LISM). Three-dimensional (3D) MHD simulations with a kinetic treatment for neutrals and PUIs are currently still not viable. In light of recent energetic neutral atom (ENA) observations by the Interstellar Boundary EXplorer, the purpose of this paper is to illustrate the complex coupling between PUIs across the heliopause (HP) as facilitated by ENAs using estimates of PUI properties extracted from a 3D MHD simulation of the SW-LISM interaction with kinetic neutrals. First, we improve upon the multi-component treatment of the inner heliosheath (IHS) plasma from Zank et al. by including the extinction of PUIs through charge-exchange. We find a significant amount of energy is transferred away from hot, termination shock-processed PUIs into a colder, "freshly injected" PUI population. Second, we extend the multi-component approach to estimate ENA flux from the outer heliosheath (OHS), formed from charge-exchange between interstellar hydrogen atoms and energetic PUIs. These PUIs are formed from ENAs in the IHS that crossed the HP and experienced charge-exchange. Our estimates, based on plasma-neutral simulations of the SW-LISM interaction and a post-processing analysis of ENAs and PUIs, suggest the majority of flux visible at 1 AU from the front of the heliosphere, between ~0.02 and 10 keV, originates from OHS PUIs, indicating strong coupling between the IHS and OHS plasmas through charge-exchange.

  8. Recent Excitation, Charge Exchange, and Lifetime Results in Highly Charged Ions Relevant to Stellar, Interstellar, Solar and Comet Phenomena

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Hossain, S.; Mawhorter, R. J.; Smith, S. J.

    2006-01-01

    Recent JPL absolute excitation and charge exchange cross sections, and measurements of lifetimes of metastable levels in highly-charged ions (HCIs) are reported. These data provide benchmark comparisons to results of theoretical calculations. Theoretical approaches can then be used to calculate the vast array of data which cannot be measured due to experimental constraints. Applications to the X-ray emission from comets are given.

  9. Analysis of the Charge Exchange Between the Human Body and Ground: Evaluation of “Earthing” From an Electrical Perspective

    PubMed Central

    Chamberlin, Kent; Smith, Wayne; Chirgwin, Christopher; Appasani, Seshank; Rioux, Paul

    2014-01-01

    Objective The purpose of this study was to investigate “earthing” from an electrical perspective through measurement and analysis of the naturally occurring electron flow between the human body or a control and ground as this relates to the magnitude of the charge exchange, the relationship between the charge exchange and body functions (respiration and heart rate), and the detection of other information that might be contained in the charge exchange. Methods Sensitive, low-noise instrumentation was designed and fabricated to measure low-level current flow at low frequencies. This instrumentation was used to record current flow between human subjects or a control and ground, and these measurements were performed approximately 40 times under varied circumstances. The results of these measurements were analyzed to determine if information was contained in the current exchange. Results The currents flowing between the human body and ground were small (nanoamperes), and they correlated with subject motion. There did not appear to be any information contained in this exchange except for information about subject motion. Conclusions This study showed that currents flow between the environment (earth) and a grounded human body; however, these currents are small (nanoamperes) and do not appear to contain information other than information about subject motion. PMID:25435837

  10. Charge exchange of metastable 2D oxygen ions with molecular oxygen - A new source of thermospheric O2/+/ ions

    NASA Technical Reports Server (NTRS)

    Torr, D. G.; Torr, M. R.; Rusch, D. W.; Nier, A. O.; Kayser, D.; Hanson, W. B.; Hoffman, J. H.; Donahue, K.

    1979-01-01

    Reactions involving metastable ions are difficult to study in the laboratory. Much new information on these reactions has been derived from satellite measurements of aeronomic parameters. In this paper, Atmosphere Explorer D data are used to study charge exchange of metastable O(+)(2D) ions with O2. Using direct measurements of the O2 at 200 km to compute O2 densities at 300 km and supporting ionic concentrations and temperature observations, we find the rate coefficient for this reaction to be 1 + or - 0.6 times 10 to the minus 9th cu cm/sec. The process constitutes a significant source of O2(+) ions in the F2 layer at times when the N2 and O2 densities are enhanced. This finding leads to the conclusion that charge exchange with O2 must be a major sink for O(+)(2D) and an important source of O2(+) ions in the E region, because of the increase in the O2 concentration/N2 concentration ratio with decreasing altitude. The results imply that 80% of all O(+) ions formed in the E region are converted to O2(+) and that only about 20% of the metastable O(+) ions are converted into N2(+) through charge exchange with N2.

  11. Charge exchange produced K-shell x-ray emission from Ar16+ in a tokamak plasma with neutral beam injection

    SciTech Connect

    Beiersdorfer, P; Bitter, M; Marion, M; Olson, R E

    2004-12-27

    High-resolution spectroscopy of hot tokamak plasma seeded with argon ions and interacting with an energetic, short-pulse neutral hydrogen beam was used to obtain the first high-resolution K-shell x-ray spectrum formed solely by charge exchange. The observed K-shell emission of Ar{sup 16+} is dominated by the intercombination and forbidden lines, providing clear signatures of charge exchange. Results from an ab initio atomic cascade model provide excellent agreement, validating a semiclassical approach for calculating charge exchange cross sections.

  12. Interpretation of experimental differential elastic scattering cross section for H/+/ + Ne.

    NASA Technical Reports Server (NTRS)

    Bobbio, S. M.; Rich, W. G.; Doverspike, L. D.; Champion, R. L.

    1971-01-01

    The interatomic V(r) found by potential-model calculations is compared to an ab initio calculation of the intermolecular potential for NeH+ due to Peyerimhoff (1965). The reason for a rather significant difference in the two results is discussed, and a new method due to Remler (1971) involving Regge poles is applied. The method can be used to calculate the differential cross section, where the starting point for such calculations is based on intuition in light of the classical deflection function.

  13. Measurement of the absolute differential cross section for np elastic scattering at 194 MeV

    SciTech Connect

    Sarsour, M.; Peterson, T.; Planinic, M.; Vigdor, S. E.; Allgower, C.; Hossbach, T.; Jacobs, W. W.; Klyachko, A. V.; Rinckel, T.; Stephenson, E. J.; Wissink, S. W.; Zhou, Y.; Bergenwall, B.; Blomgren, J.; Johansson, C.; Klug, J.; Nadel-Turonski, P.; Nilsson, L.; Olsson, N.; Pomp, S.

    2006-10-15

    A tagged medium-energy neutron beam was used in a precise measurement of the absolute differential cross section for np backscattering. The results resolve significant discrepancies within the np database concerning the angular dependence in this regime. The experiment has determined the absolute normalization with {+-}1.5% uncertainty, suitable to verify constraints of supposedly comparable precision that arise from the rest of the database in partial wave analyses. The analysis procedures, especially those associated with the evaluation of systematic errors in the experiment, are described in detail so that systematic uncertainties may be included in a reasonable way in subsequent partial wave analysis fits incorporating the present results.

  14. Combinational effect of matrix elasticity and alendronate density on differentiation of rat mesenchymal stem cells.

    PubMed

    Jiang, Pengfei; Mao, Zhengwei; Gao, Changyou

    2015-06-01

    Differentiation of mesenchymal stem cells (MSCs) is regulated by multivariate physical and chemical signals in a complicated microenvironment. In this study, polymerizable double bonds (GelMA) and osteo-inductive alendronate (Aln) (Aln-GelMA) were sequentially grafted onto gelatin molecules. The biocompatible hydrogels with defined stiffness in the range of 4-40 kPa were prepared by using polyethylene glycol diacrylate (PEGDA) as additional crosslinker. The Aln density was adjusted from 0 to 4 μM by controlling the ratio between the GelMA and Aln-GelMA. The combinational effects of stiffness and Aln density on osteogenic differentiation of MSCs were then studied in terms of ALP activity, collagen type I and osteocalcin expression, and calcium deposition. The results indicated that the stiffness and Aln density could synergistically improve the expression of all these osteogenesis markers. Their osteo-inductive effects are comparable to some extent, and high Aln density could be more effective than the stiffness.

  15. Membrane Elasticity and Mediated Interactions in Continuum Theory: A Differential Geometric Approach

    NASA Astrophysics Data System (ADS)

    Deserno, Markus

    Biomembranes are fantastically complex systems [1-4]: hundreds of different lipid and protein species self-assemble into a large two-dimensional aggregate of locally complex and laterally inhomogeneous structure, and a globally potentially daunting topology. Thermal motion of this elastically soft system contributes prominently to its properties, and active processes constantly drive it away from equilibrium. How can we ever hope to learn something quantitative about such a complicated thing? The route to success lies — as so often in physics — in the observation that we can frefectly well described by an effective Hamiltonian, whose small number of phenomenological parameters depend on — and can in principle be determined from — the underlying microscopic physics. Yet, establishing this micro-macro relation is not prerequisite to a successful ing steps can be performed, thus constructing a hierarchy of scales with much beautiful physics in the different tiers. For instance, the laws of quantum mechanics explain everything about water that we need to know — e.g., how water structure and hydrogen bonds give rise to many of water's anomalies — but we can often just describe it effectively as a substance with some measurable material parameters, such as density, heat of vaporization, melting point, and compressibility. And even of these parameters many become irrelevant if we're only interested in large-scale fluid motion, for which density and viscosity are often the only relevant properties. Having gotten so used to this separability, we sometimes even forget that the success of physics as a science rests entirely on it. If phenomena on different scales could not be disentangled, we would for instance not be able to describe the motion of the liquid in a stirred cup of coffee without a thorough appreciation of its atomic structure. Or, maybe we'd even need to understand quarks? Or strings? The fact that for all intents and purposes we can master our

  16. Joy of cex: Sharpening the (t,He-3) probe at 345 MeV for the charge-exchange knife drawer

    NASA Astrophysics Data System (ADS)

    Howard, Meredith E.

    This data set represents the first step in a campaign of (t, 3He) charge-exchange experiments at the National Superconducting Cyclotron Laboratory designed explicitly to measure Gamow-Teller strength distributions in the electron capture direction for stable medium-heavy atomic nuclei, with particular interest in reaching the nuclei in the pf -shell or masses up to A=112. The 115 MeV/nucleon secondary triton beam with an average intensity of 4x106 pps on 10 mg/cm2 thick target foils produces 3He that are measured in the focal plane detectors of the S800 magnetic spectrometer. From these data, the scattering angle of the tritons is reconstructed to within 7 mrad and the energy of the recoil nucleus is reconstructed to better then 250 keV. Since there is no comprehensive study of the (t, 3He) probe for triton energies of 100-400 MeV/nucleon, this data is the first step in evaluating the advantages of extracting B(GT) from the (t,3He) probe over other hadronic probes. The first target is a CD2 target used for calibrating cross section. This is the third measurement for the (t, 3He) probe on 12C above 100 MeV/nucleon. The present 12C(t,3He) cross section for the 12B ground state (Jpi = 1 +) is lower than a previous measurement at the NSCL by more than one standard deviation in uncertainty but agrees with 12C( 3He,t)12N. This (t,3He) measurement for 24Mg, the second target, is the first above 100 MeV/nucleon. The B(GT) distribution for 24Na is extracted from differential cross sections as a function of residual nucleus excitation energy up to 7 MeV. For each peak in excitation energy, the differential cross section as a function of reconstructed scattering angle is extrapolated to zero degrees using angular distrubutions calculated with the distorted wave calculations from the code FOLD and transformed to q = 0 zero momentum transfer. Uncertainties in the B(GT) include a calculation of interference to Jpi=1 + expected from DeltaL=2, DeltaS=1 reactions. Comparisons of B

  17. Influence of differential elastic nucleon-nucleon cross section on stopping and collective flow in heavy-ion collisions at intermediate energies

    NASA Astrophysics Data System (ADS)

    Wang, Yongjia; Guo, Chenchen; Li, Qingfeng; Li, Zhuxia; Su, Jun; Zhang, Hongfei

    2016-08-01

    We considered three different nucleon-nucleon (NN) elastic differential cross sections: the Cugnon et al. parameterized differential cross section [Nucl. Instrum. Methods Phys. Res., Sect. B 111, 215 (1996), 10.1016/0168-583X(95)01384-9], the differential cross section derived from the collision term of the self-consistent relativistic Boltzmann-Uehling-Uhlenbeck equation proposed by Mao et al. [Z. Phys. A 347, 173 (1994), 10.1007/BF01292373], and the isotropic differential cross section within the newly updated version of the ultrarelativistic quantum molecular dynamics (UrQMD) model. By doing so, we investigated the influence of the differential elastic NN cross section on various observables (e.g., nuclear stopping, both the rapidity and transverse-velocity dependence of the directed and elliptic flows) in Au+Au collisions at beam energies 150, 250, 400, and 800 MeV /nucleon . By comparing calculations with those three differential cross sections, we found that the nuclear stopping power and the directed and elliptic flows are affected to some extent by the differential cross sections, and the impact of differential cross section on those observables becomes more visible as the beam energy increases. The effect on the elliptic flow difference v2n-v2H and ratio v2n/v2H of neutrons versus hydrogen isotopes (Z =1 ), which have been used as sensitive observables for probing nuclear symmetry energy at high densities, is weak.

  18. Osteogenic differentiation of human mesenchymal stem cells on α5 integrin binding peptide hydrogels is dependent on substrate elasticity

    PubMed Central

    Gandavarapu, Navakanth R.; Alge, Daniel L.; Anseth, Kristi S.

    2014-01-01

    The extracellular matrix plays a crucial role in controlling human mesenchymal stem cell (hMSC) biology including differentiation, and α5β1 integrin signaling plays an important role during osteogenic differentiation of hMSCs. Here, peptide-functionalized hydrogels were used to examine the role of α5β1 integrin signaling in inducing osteogenic differentiation in hMSCs. Further, the role of substrate elasticity was also studied. A thiolene chemistry was used to functionalize poly(ethylene glycol) hydrogels with a pendant peptide moieity, c(RRETAWA), as previous studies have shown that RRETAWA containing peptides bind to the α5β1 integrin with very high specificity. Notably, hMSC attachment to c(RRETAWA)-functionalized hydrogels was found to occur primarily through α5 integrins, as the number of attached cells was significantly reduced to ~20% upon blocking the α5 integrin during culture. To investigate the interplay between stiffness and c(RRETAWA) concentration, hydrogels were formulated with Young’s moduli of ~2 kPa (soft) and ~25 kPa (stiff) and c(RRETAWA) concentrations of 0.1 mM and 1 mM. Stiff substrates led to ~3.5 fold higher hMSC attachment and ~3 fold higher cell area in comparison to soft substrates. hMSCs formed robust and larger focal adhesions on stiff substrates at 1 mM c(RRETAWA) compared to soft substrates. Alkaline phosphatase (ALP) activity in hMSCs cultured on stiff gels at 0.1 mM and 1 mM c(RRETAWA) was increased 2.5 and 3.5 fold, respectively after 14 days in growth media. hMSCs did not show an increase in ALP activity when cultured on soft gels. Further, gene expression of osteogenic related genes, core binding factor-1, osteopontin and Collagen-1a at day 14 in hMSCs cultured on stiff gels at 1 mM c(RRETAWA) were increased 10, 7 and 4 fold, respectively, while on soft gels, gene expression was at basal levels. Collectively, these results demonstrate that the combination of high substrate stiffness and α5β1 integrin signaling

  19. Removing Spectral Diagnostics of Galactic and Stellar X-Ray Emission from Charged Exchange Recombination

    NASA Technical Reports Server (NTRS)

    Wargelin, Brad

    2004-01-01

    Our research uses the electron beam ion trap (EBIT) at the Lawrence Livermore National Laboratory to study X-ray emission from the charge exchange (CX) of highly charged ions with neutral gases. The resulting data help to fill a void in existing experimental and theoretical understanding of this atomic physics process, and are needed to explain all or part of the observed X-ray emission from the soft X-ray background, stellar winds, the Galactic Center and Galactic Ridge, supernova ejecta, and photoionized nebulae. Appreciation of the astrophysical relevance of our work continues to grow with the publication of roughly a dozen papers in the past four years describing Chandra and XMM observations of geocoronal and heliospheric CX emission, the temporal variation of such emission and correlation with X-ray emission enhancements observed by ROSAT, the theoretical spatial distribution of that emission, and CX emission around other stars. A similar number of papers were also published during that time describing CX emission from planets and comets. We expect that the launch of ASTRSE2, with its second-generation XRS microcalo- (with 6-eV resolution), will reveal even more clearly the contributions of CX to astrophysical emission. In our EBIT work we collected CX spectra from such ions as H-like and He-like Ne, Ar, and Fe. Our early measurements were made with a high-purity Ge detector, but during the second year we began operation of the first-generation XRS microcalorimeter (a twin of the XRS on ASTRO-E) and greatly improved the resolution of our measurements from roughly 150 eV (FWHM) with the Ge detectors to 10 eV with the XRS. We found that saturation of the XRS counting apparatus, which we described in our proposal as a potential concern, is not a problem for studying CX. During the course of our research, we expanded the number of injection gases permitted by the LLNL safety team, purchased and eventually operated an atomic H source, and clearly demonstrated the

  20. Measurement of the antineutrino double-differential charged-current quasi-elastic scattering cross section at MINERvA

    NASA Astrophysics Data System (ADS)

    Patrick, Cheryl Elizabeth

    Next-generation neutrino oscillation experiments, such as DUNE and Hyper-Kamiokande, hope to measure charge-parity (CP) violation in the lepton sector. In order to do this, they must dramatically reduce their current levels of uncertainty, particularly those due to neutrino-nucleus interaction models. As CP violation is a measure of the difference between the oscillation properties of neutrinos and antineutrinos, data about how the less-studied antineutrinos interact is especially valuable. We present the MINERvA experiment's first double-differential scattering cross sections for antineutrinos on scintillator, in the few-GeV range relevant to experiments such as DUNE and NOvA. We also present total antineutrino-scintillator quasi-elastic cross sections as a function of energy, which we compare to measurements from previous experiments. As well as being useful to help reduce oscillation experiments' uncertainty, our data can also be used to study the prevalence of various correlation and final-state interaction effects within the nucleus. We compare to models produced by different model generators, and are able to draw first conclusions about the predictions of these models.

  1. Hydration dependence of myoglobin dynamics studied with elastic neutron scattering, differential scanning calorimetry and broadband dielectric spectroscopy.

    PubMed

    Fomina, Margarita; Schirò, Giorgio; Cupane, Antonio

    2014-01-01

    In this work we present a thorough investigation of the hydration dependence of myoglobin dynamics. The study is performed on D2O-hydrated protein powders in the hydration range 0Elastic Neutron Scattering using the spectrometer IN13 at ILL (Grenoble), while the relaxations of the protein+hydration water system are investigated with Broadband Dielectric Spectroscopy; finally, Differential Scanning Calorimetry is used to obtain a thermodynamic description of the system. The effect of increasing hydration is to speed up the relaxations of the myoglobin+hydration water system and, thermodynamically, to decrease the glass transition temperature; these effects tend to saturate at h values greater than ~0.3. Moreover, the calorimetric scans put in evidence the occurrence of an endothermic peak whose onset temperature is located at ~230K independent of hydration. From the point of view of the protein equilibrium fluctuations, while the amplitude of anharmonic mean square displacements is found to increase with hydration, their onset temperature (i.e. the onset temperature of the well known "protein dynamical transition") is hydration independent. On the basis of the above results, the relevance of protein+hydration water relaxations and of the thermodynamic state of hydration water to the onset of the protein dynamical transition is discussed.

  2. Measurement of the Antineutrino Double-Differential Charged-Current Quasi-Elastic Scattering Cross Section at MINERvA

    SciTech Connect

    Patrick, Cheryl

    2016-01-01

    Next-generation neutrino oscillation experiments, such as DUNE and Hyper-Kamiokande, hope to measure charge-parity (CP) violation in the lepton sector. In order to do this, they must dramatically reduce their current levels of uncertainty, particularly those due to neutrino-nucleus interaction models. As CP violation is a measure of the difference between the oscillation properties of neutrinos and antineutrinos, data about how the less-studied antineutrinos interact is especially valuable. We present the MINERvA experiment's first double-differential scattering cross sections for antineutrinos on scintillator, in the few-GeV range relevant to experiments such as DUNE and NOvA. We also present total antineutrino-scintillator quasi-elastic cross sections as a function of energy, which we compare to measurements from previous experiments. As well as being useful to help reduce oscillation experiments' uncertainty, our data can also be used to study the prevalence of various cor relation and final-state interaction effects within the nucleus. We compare to models produced by different model generators, and are able to draw first conclusions about the predictions of these models.

  3. The atmosphere of comet 67P/Churyumov-Gerasimenko diagnosed by charge-exchanged solar wind alpha particles

    NASA Astrophysics Data System (ADS)

    Simon Wedlund, C.; Kallio, E.; Alho, M.; Nilsson, H.; Stenberg Wieser, G.; Gunell, H.; Behar, E.; Pusa, J.; Gronoff, G.

    2016-03-01

    Context. The ESA/Rosetta mission has been orbiting comet 67P/Churyumov-Gerasimenko since August 2014, measuring its dayside plasma environment. The ion spectrometer onboard Rosetta has detected two ion populations, one energetic with a solar wind origin (H+, He2+, He+), the other at lower energies with a cometary origin (water group ions such as H2O+). He+ ions arise mainly from charge-exchange between solar wind alpha particles and cometary neutrals such as H2O. Aims: The He+ and He2+ ion fluxes measured by the Rosetta Plasma Consortium Ion Composition Analyser (RPC-ICA) give insight into the composition of the dayside neutral coma, into the importance of charge-exchange processes between the solar wind and cometary neutrals, and into the way these evolve when the comet draws closer to the Sun. Methods: We combine observations by the ion spectrometer RPC-ICA onboard Rosetta with calculations from an analytical model based on a collisionless neutral Haser atmosphere and nearly undisturbed solar wind conditions. Results: Equivalent neutral outgassing rates Q can be derived using the observed RPC-ICA He+/He2+ particle flux ratios as input into the analytical model in inverse mode. A revised dependence of Q on heliocentric distance Rh in AU is found to be Rh-7.06 between 1.8 and 3.3 AU, suggesting that the activity in 2015 differed from that of the 2008 perihelion passage. Conversely, using an outgassing rate determined from optical remote sensing measurements from Earth, the forward analytical model results are in relatively good agreement with the measured RPC-ICA flux ratios. Modelled ratios in a 2D spherically-symmetric plane are also presented, showing that charge exchange is most efficient with solar wind protons. Detailed cometocentric profiles of these ratios are also presented. Conclusions: In conclusion, we show that, with the help of a simple analytical model of charge-exchange processes, a mass-capable ion spectrometer such as RPC-ICA can be used as a

  4. NUMEN Project @ LNS : Heavy ions double charge exchange reactions towards the 0νββ nuclear matrix element determination

    SciTech Connect

    Agodi, C. Calabretta, L.; Calanna, A.; Carbone, D.; Cavallaro, M.; Colonna, M.; Cuttone, G.; Finocchiaro, P.; Pandola, L.; Rifuggiato, D.; Tudisco, S.; Cappuzzello, F.; Greco, V.; Bonanno, D. L.; Bongiovanni, D. G.; Longhitano, F.; Branchina, V.; Foti, A.; Lo Presti, D.; Lanzalone, G.; and others

    2015-10-28

    In the NUMEN Project it is proposed an innovative technique to access the nuclear matrix elements entering in the expression of the life-time of the neutrinoless double beta decay, using relevant cross sections of double charge exchange reactions. A key aspect is the use of MAGNEX large acceptance magnetic spectrometer, for the detection of the ejectiles, and of the INFN Laboratori Nazionali del Sud (LNS) K800 Superconducting Cyclotron (CS), for the acceleration of the required high resolution and low emittance heavy-ion beams.

  5. STRUCTURE OF THE INTERSTELLAR BOUNDARY EXPLORER RIBBON FROM SECONDARY CHARGE-EXCHANGE AT THE SOLAR–INTERSTELLAR INTERFACE

    SciTech Connect

    Zirnstein, E. J.; McComas, D. J.; Heerikhuisen, J. E-mail: dmccomas@swri.edu

    2015-05-01

    In 2009, the Interstellar Boundary Explorer discovered a bright “ribbon” of energetic neutral atom (ENA) flux in the energy range ≤0.4–6 keV, encircling a large portion of the sky. This observation was not previously predicted by any models or theories, and since its discovery, it has been the subject of numerous studies of its origin and properties. One of the most studied mechanisms for its creation is the “secondary ENA” process. Here, solar wind ions, neutralized by charge-exchange with interstellar atoms, propagate outside the heliopause; experience two charge-exchange events in the dense outer heliosheath; and then propagate back inside the heliosphere, preferentially in the direction perpendicular to the local interstellar magnetic field. This process has been extensively analyzed using state-of-the-art modeling and simulation techniques, but it has been difficult to visualize. In this Letter, we show the three-dimensional structure of the source of the ribbon, providing a physical picture of the spatial and energy scales over which the secondary ENA process occurs. These results help us understand how the ribbon is generated and further supports a secondary ENA process as the leading ribbon source mechanism.

  6. Structure of the Interstellar Boundary Explorer Ribbon from Secondary Charge-exchange at the Solar-Interstellar Interface

    NASA Astrophysics Data System (ADS)

    Zirnstein, E. J.; Heerikhuisen, J.; McComas, D. J.

    2015-05-01

    In 2009, the Interstellar Boundary Explorer discovered a bright “ribbon” of energetic neutral atom (ENA) flux in the energy range ≤0.4-6 keV, encircling a large portion of the sky. This observation was not previously predicted by any models or theories, and since its discovery, it has been the subject of numerous studies of its origin and properties. One of the most studied mechanisms for its creation is the “secondary ENA” process. Here, solar wind ions, neutralized by charge-exchange with interstellar atoms, propagate outside the heliopause; experience two charge-exchange events in the dense outer heliosheath; and then propagate back inside the heliosphere, preferentially in the direction perpendicular to the local interstellar magnetic field. This process has been extensively analyzed using state-of-the-art modeling and simulation techniques, but it has been difficult to visualize. In this Letter, we show the three-dimensional structure of the source of the ribbon, providing a physical picture of the spatial and energy scales over which the secondary ENA process occurs. These results help us understand how the ribbon is generated and further supports a secondary ENA process as the leading ribbon source mechanism.

  7. Cometary Solar Wind Charge Exchange Line Ratios: Source of X-rays in Comet C/2000 WM1 (linear)

    NASA Astrophysics Data System (ADS)

    Mullen, Patrick Dean; Cumbee, Renata; Lyons, David; Gu, Liyi; Kaastra, Jelle S.; Shelton, Robin L.; Stancil, Phillip C.

    2016-06-01

    Cometary solar wind charge exchange (C-SWCX) occurs when highly charged projectile ions present in solar wind capture an electron from a target neutral species present in the cometary atmosphere. The availability of atomic and molecular data necessary for the X-ray emission modeling due to C-SWCX is limited; therefore, we apply multi-channel Landau-Zener (MCLZ) theory (Mullen et al. 2016) to generate cross section data and theoretical X-ray line ratios for a variety of bare and non-bare ion single electron capture (SEC) collisions. Namely, we consider collisions between the solar wind constituent H-like and He-like ions of C, N, O, Ne, Na, Al, and Si and the cometary neutrals H, H2O, CO, CO2, OH, and O. To exemplify the application of this data, we model the X-ray emission of comet C/2000 WM1 (linear) using the charge exchange package in SPEX (Gu et al. 2015) and find excellent agreement with observations made with the XMM-RGS detector. Our analyses show that the X-ray intensity is dominated by C-SWCX with H.Work at UGA was partially funded by NASA grant NNX13AF31G.References:Gu et al. 2016, A&A, accepted 22 January 2016Mullen et al. 2016, ApJS, in press

  8. Operation of the TFTR Pellet Charge Exchange Diagnostic in the Pulse Counting Mode during H+ RF-minority Heating

    SciTech Connect

    Medley, S.S., PPPL

    1998-05-01

    The Pellet Charge Exchange technique on TFTR has been used primarily to obtain active charge exchange measurements using a high energy (0.5 - 4.0 MeV) neutral particle analyzer (NPA) in conjunction with impurity pellet injection (Li and B) with the scintillator-photomultiplier detector system operated in the current mode. While passive measurements using pulse counting were also obtained using this instrumentation, operation in this mode was very restrictive with pulse counting rates limited to less than {approximately}10 kHz in the absence of any significant neutron and gamma induced background signal. An upgrade to a specialized pulse counting capability which was developed by the Ioffe Institute was implemented which consisted of CsI(Tl) scintillators having features designed to minimize signals induced by background neutron and gamma rays and 16-channel pulse height analysis electronics on each of the eight NPA energy channels. Passive measurements of RF-driven energetic hydrogen minority ions which served to verify operation of the pulse counting mode are reported. It is shown that in the passive mode the main donors for the neutralization of H+ ions in this energy range are C5+ ions. The measured effective H+ tail temperatures range from 0.15 MeV at an RF power of 2 MW to 0.35 MeV at 6 MW.

  9. The effect of the charge exchange source on the velocity and 'temperature' distributions and their anisotropies in the earth's exosphere

    NASA Technical Reports Server (NTRS)

    Hodges, R. R., Jr.; Rohrbaugh, R. P.; Tinsley, B. A.

    1981-01-01

    The velocity distribution of atomic hydrogen in the earth's exosphere is calculated as a function of altitude and direction taking into account both the classic exobase source and the higher-altitude plasmaspheric charge exchange source. Calculations are performed on the basis of a Monte Carlo technique in which random ballistic trajectories of individual atoms are traced through a three-dimensional grid of audit zones, at which relative concentrations and momentum or energy fluxes are obtained. In the case of the classical exobase source alone, the slope of the velocity distribution is constant only for the upward radial velocity component and increases dramatically with altitude for the incoming radial and transverse velocity components, resulting in a temperature decrease. The charge exchange source, which produces the satellite hydrogen component and the hot ballistic and escape components of the exosphere, is found to enhance the wings of the velocity distributions, however this effect is not sufficient to overcome the temperature decreases at altitudes above one earth radius. The resulting global model of the hydrogen exosphere may be used as a realistic basis for radiative transfer calculations.

  10. Design and operation of the pellet charge exchange diagnostic for measurement of energetic confined alphas and tritons on TFTR

    SciTech Connect

    Medley, S.S.; Duong, H.H.; Fisher, R.K.

    1996-05-01

    Radially-resolved energy and density distributions of the energetic confined alpha particles in D-T experiments on TFTR are being measured by active neutral particle analysis using low-Z impurity pellet injection. When injected into a high temperature plasma, an impurity pellet (e.g. Lithium or Boron) rapidly ablates forming an elongated cloud which is aligned with the magnetic field and moves with the pellet. This ablation cloud provides a dense target with which the alpha particles produced in D-T fusion reactions can charge exchange. A small fraction of the alpha particles incident on the pellet ablation cloud will be converted to helium neutrals whose energy is essentially unchanged by the charge transfer process. By measuring the resultant helium neutrals escaping from the plasma using a mass and energy resolving charge exchange analyzer, this technique offers a direct measurement of the energy distribution of the incident high-energy alpha particles. Other energetic ion species can be detected as well, such as tritons generated in D-D plasmas and H or He{sup 3} RF-driven minority ion tails. The diagnostic technique and its application on TFTR are described in detail.

  11. The effect of the charge exchange source on the velocity and 'temperature' distributions and their anisotropies in the earth's exosphere

    NASA Astrophysics Data System (ADS)

    Hodges, R. R., Jr.; Rohrbaugh, R. P.; Tinsley, B. A.

    1981-08-01

    The velocity distribution of atomic hydrogen in the earth's exosphere is calculated as a function of altitude and direction taking into account both the classic exobase source and the higher-altitude plasmaspheric charge exchange source. Calculations are performed on the basis of a Monte Carlo technique in which random ballistic trajectories of individual atoms are traced through a three-dimensional grid of audit zones, at which relative concentrations and momentum or energy fluxes are obtained. In the case of the classical exobase source alone, the slope of the velocity distribution is constant only for the upward radial velocity component and increases dramatically with altitude for the incoming radial and transverse velocity components, resulting in a temperature decrease. The charge exchange source, which produces the satellite hydrogen component and the hot ballistic and escape components of the exosphere, is found to enhance the wings of the velocity distributions, however this effect is not sufficient to overcome the temperature decreases at altitudes above one earth radius. The resulting global model of the hydrogen exosphere may be used as a realistic basis for radiative transfer calculations.

  12. Elastic Differential Cross Sections

    NASA Technical Reports Server (NTRS)

    Werneth, Charles M.; Maung, Khin M.; Ford, William P.; Norbury, John W.; Vera, Michael D.

    2014-01-01

    The eikonal, partial wave (PW) Lippmann-Schwinger, and three-dimensional Lippmann-Schwinger (LS3D) methods are compared for nuclear reactions that are relevant for space radiation applications. Numerical convergence of the eikonal method is readily achieved when exact formulas of the optical potential are used for light nuclei (A less than or equal to 16) and the momentum-space optical potential is used for heavier nuclei. The PW solution method is known to be numerically unstable for systems that require a large number of partial waves, and, as a result, the LS3D method is employed. The effect of relativistic kinematics is studied with the PW and LS3D methods and is compared to eikonal results. It is recommended that the LS3D method be used for high energy nucleon- nucleus reactions and nucleus-nucleus reactions at all energies because of its rapid numerical convergence and stability.

  13. Traveltime dispersion in an isotropic elastic mantle: strong lower-mantle signal in differential-frequency residuals

    NASA Astrophysics Data System (ADS)

    Schuberth, Bernhard S. A.; Zaroli, Christophe; Nolet, Guust

    2015-12-01

    We study wavefield effects of direct P- and S-waves in elastic and isotropic 3-D seismic structures derived from the temperature field of a high-resolution mantle circulation model. More specifically, we quantify the dispersion of traveltime residuals caused by diffraction in structures with dynamically constrained length scales and magnitudes of the lateral variations in seismic velocities and density. 3-D global wave propagation is simulated using a spectral element method. Intrinsic attenuation (i.e. dissipation of seismic energy) is deliberately neglected, so that any variation of traveltimes with frequency can be attributed to structural effects. Traveltime residuals are measured at 15, 22.5, 34 and 51 s dominant periods by cross-correlation of 3-D and 1-D synthetic waveforms. Additional simulations are performed for a model in which 3-D structure is removed in the upper 800 km to isolate the dispersion signal of the lower mantle. We find that the structural length scales inherent to a vigorously convecting mantle give rise to significant diffraction-induced body-wave traveltime dispersion. For both P- and S-waves, the difference between long-period and short-period residuals for a given source-receiver pair can reach up to several seconds for the period bands considered here. In general, these `differential-frequency' residuals tend to increase in magnitude with increasing short-period delay. Furthermore, the long-period signal typically is smaller in magnitude than the short-period one; that is, wave-front healing is efficient independent of the sign of the residuals. Unlike the single-frequency residuals, the differential-frequency residuals are surprisingly similar between the `lower-mantle' and the `whole-mantle' model for corresponding source-receiver pairs. The similarity is more pronounced in case of S-waves and varies between different combinations of period bands. The traveltime delay acquired in the upper mantle seems to cancel in these differential

  14. Traveltime dispersion in an isotropic elastic mantle: strong lower-mantle signal in differential-frequency residuals

    NASA Astrophysics Data System (ADS)

    Schuberth, Bernhard; Zaroli, Christophe; Nolet, Guust

    2016-04-01

    Recently, we developed a joint forward modelling approach to test geodynamic hypotheses directly against seismic observations. By computing 3-D global wave propagation in seismic models derived from simulations of mantle flow, synthetic seismograms are generated independent of any seismic data. Here, we now show that this is also an excellent tool to study wavefield effects in a consistent manner, as length scales and magnitudes of seismic heterogeneity in the models are constrained by the dynamics of the flow. In this study, we quantify the traveltime dispersion of P- and S-waves caused by diffraction in our elastic and isotropic 3-D synthetic seismic structures. Intrinsic attenuation (i.e. dissipation of seismic energy) is deliberately neglected, so that any variation of traveltimes with frequency can be attributed to structural effects. Traveltime residuals are measured at 15, 22.5, 34 and 51 s dominant periods by cross-correlation of 3-D and 1-D synthetic waveforms. Additional simulations are performed for a model in which 3-D structure is removed in the upper 800 km to isolate the dispersion signal of the lower mantle. We find that the structural length scales inherent to a vigorously convecting mantle give rise to significant diffraction-induced body-wave traveltime dispersion. For both P- and S-waves, the difference between long-period and short-period residuals for a given source-receiver pair can reach up to several seconds for the period bands considered here. In general, these 'differential-frequency' residuals tend to increase in magnitude with increasing short-period delay. Furthermore, the long-period signal typically is smaller in magnitude than the short-period one; that is, wave-front healing is efficient independent of the sign of the residuals. Unlike the single-frequency residuals, the differential-frequency residuals are surprisingly similar between the 'lower-mantle' and the 'whole-mantle' model for corresponding source-receiver pairs. The

  15. A comparison of experimental and computer model results on the charge-exchange plasma flow from a 30 cm mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Gabriel, S. B.; Kaufman, H. R.

    1982-01-01

    Ion thrusters can be used in a variety of primary and auxiliary space-propulsion applications. A thruster produces a charge-exchange plasma which can interact with various systems on the spacecraft. The propagation of the charge-exchange plasma is crucial in determining the interaction of that plasma with the spacecraft. This paper compares experimental measurements with computer model predictions of the propagation of the charge-exchange plasma from a 30 cm mercury ion thruster. The plasma potentials, and ion densities, and directed energies are discussed. Good agreement is found in a region upstream of, and close to, the ion thruster optics. Outside of this region the agreement is reasonable in view of the modeling difficulties.

  16. Tests of effective interactions for nucleon scattering and charge exchange below 60 MeV

    SciTech Connect

    Dietrich, F.S.; Petrovich, F.

    1984-11-01

    Significant progress has been made over the past several years in developing energy-and density-dependent effective interactions and optical potentials based on free nucleon-nucleon potentials. This leads to the hope that the nucleon-scattering reaction mechanism may be well enough to probe details of nuclear spectroscopy (i.e., transition densities) more accurately than with purely phenomenological approaches. Of particular interest to this conference is the possibility of separating neutron and proton transition densitiies by comparing proton and neutron scattering, which can be done reliably only if the isovector parts of the effective interaction are well known. This paper attempts to assess the accuracy of presently available interactions through comparisons with elastic and inelastic scattering over a wide mass range, and also the (p,n) isobaric-analog reaction. Particular emphasis has been placed on the isovector parts of the interaction and on Coulomb corrections by comparing proton and neutron scattering on the same targets. In a number of cases, precise neutron data have been measured to facilitate these comparisons. 46 references.

  17. Charge-exchange measurements of beam ion thermalization in MHD-quiescent plasmas in the Poloidal Divertor Experiment

    SciTech Connect

    Kaita, R.; Goldston, R.J.; Beiersdorfer, P.; Herndon, D.L.; Kaye, S.M.; Kugel, H.W.; McCann, R.T.; McCune, D.C.; Meyerhofer, D.D.; Towner, H.H.

    1984-10-01

    The horizontally scanning, multiangle charge-exchange analyzer on the Poloidal Divertor Experiment (PDX) was used to study the beam ion slowing-down process with high-power perpendicular injection. Measurements were made over a wide range in toroidal field (8 kG < B(T) < 22 kG), plasma current (200 kA < I(p) < 500 kA), and beam power (1 MW < P/sub B/ < 7 MW). In MHD-quiescent plasmas, good agreement is found between the measured slowing-down spectra and theoretical predictions as a function of both angle and energy. Classes of prompt orbit losses are observed with both co- and counter-injection which have been understood and applied to plasma diagnostics. The effects of MHD activity on fast ion thermalization will be the subject of a companion paper.

  18. The T{sub z} = -1{yields}T{sub z} =0 beta decays and comparison with Charge Exchange reactions

    SciTech Connect

    Molina, F.; Rubio, B.; Fujita, Y.; Gelletly, W.; Collaboration: Santiago Collaboration

    2011-11-30

    Gamow-Teller (GT) transitions can be studied in both {beta} decay and charge exchange (CE) reactions. If isospin is a good quantum number, then the Tz = -1{yields}0 and Tz = +1{yields}0GT mirror transitions, are identical. Therefore, a comparison of the results from studies of {beta} decay and CE should shed light on this assumption. Accordingly we have studied the {beta} decay of the Tz = -1 fp-shell nuclei, {sup 54}Ni, {sup 50}Fe, {sup 46}Cr, and {sup 42}Ti, produced in fragmentation and we have compared our results with the spectra from ({sup 3}He, t) measurements on the mirror Tz = +1 target nuclei studied in high resolution at RCNP, Osaka. The {beta} decay experiments were performed as part of the STOPPED beam RISING campaign at GSI.

  19. Optimization of a compact multicusp He{sup +} ion source for double-charge-exchanged He{sup -} beam

    SciTech Connect

    Shinto, K.; Sugawara, H.; Takenaga, M.; Takeuchi, S.; Tanaka, N.; Okamoto, A.; Kitajima, S.; Sasao, M.; Nishiura, M.; Wada, M.

    2006-03-15

    Preliminary test bench results to study the beam quality extracted from a compact multicusp He{sup +} ion source for He{sup -} beam production are reported. The bench is a part of the beam diagnostic system equipped with energy analyzers, emittance meters, focusing beam optics, an alkali-metal charge-exchange cell, a neutral particle energy analyzer, a double focusing magnetic momentum analyzer, a postaccelerator, and a drift tube. Utilizing the front end of the bench, the transverse emittance and the energy distribution function of a He{sup +} beam extracted from a multi-line-cusp magnetic-field ion source 8 cm in diameter and 9 cm in length were measured. The results indicated that improvements in both formation of the plasma meniscus and reinforcement of pumping in the extraction region are necessary to produce a higher brightness He{sup +} beam.

  20. Monte Carlo simulation of ion-neutral charge exchange collisions and grid erosion in an ion thruster

    NASA Technical Reports Server (NTRS)

    Peng, Xiaohang; Ruyten, Wilhelmus M.; Keefer, Dennis

    1991-01-01

    A combined particle-in-cell (PIC)/Monte Carlo simulation model has been developed in which the PIC method is used to simulate the charge exchange collisions. It is noted that a number of features were reproduced correctly by this code, but that its assumption of two-dimensional axisymmetry for a single set of grid apertures precluded the reproduction of the most characteristic feature of actual test data; namely, the concentrated grid erosion at the geometric center of the hexagonal aperture array. The first results of a three-dimensional code, which takes into account the hexagonal symmetry of the grid, are presented. It is shown that, with this code, the experimentally observed erosion patterns are reproduced correctly, demonstrating explicitly the concentration of sputtering between apertures.

  1. Charge-exchange and fusion reaction measurements during compression experiments with neutral beam heating in the Tokamak Fusion Test Reactor

    SciTech Connect

    Kaita, R.; Heidbrink, W.W.; Hammett, G.W.; Chan, A.A.; England, A.C.; Hendel, H.W.; Medley, S.S.; Nieschmidt, E.; Roquemore, A.L.; Scott, S.D.

    1986-04-01

    Adiabatic toroidal compression experiments were performed in conjunction with high power neutral beam injection in the Tokamak Fusion Test Reactor (TFTR). Acceleration of beam ions to energies nearly twice the injection energy was measured with a charge-exchange neutral particle analyzer. Measurements were also made of 2.5 MeV neutrons and 15 MeV protons produced in fusion reactions between the deuterium beam ions and the thermal deuterium and /sup 3/He ions, respectively. When the plasma was compressed, the d(d,n)/sup 3/He fusion reaction rate increased a factor of five, and the /sup 3/He(d,p)/sup 4/He rate by a factor of twenty. These data were simulated with a bounce-averaged Fokker-Planck program, which assumed conservation of angular momentum and magnetic moment during compression. The results indicate that the beam ion acceleration was consistent with adiabatic scaling.

  2. What Can Be Learned from X-Ray Spectroscopy Concerning Hot Gas in the Local Bubble and Charge Exchange Processes?

    NASA Technical Reports Server (NTRS)

    Snowden, S. L.

    2008-01-01

    Both solar wind charge exchange emission and diffuse thermal emission from the Local Bubble are strongly dominated in the soft X-ray band by lines from highly ionized elements. While both processes share many of the same lines, the spectra should differ significantly due to the different production mechanisms, abundances, and ionization states. Despite their distinct spectral signatures, current and past observatories have lacked the spectral resolution to adequately distinguish between the two sources. High-resolution X-ray spectroscopy instrumentation proposed for future missions has the potential to answer fundamental questions such as whether there is any hot plasma in the Local Hot Bubble, and if so, what are the abundances of the emitting plasma and whether the plasma is in equilibrium. Such instrumentation will provide dynamic information about the solar wind including data on ion species which are currently difficult to track. It will also make possible remote sensing of the solar wind.

  3. Analysis of x-ray emission spectra in charge-exchange collisions of C6 + with He and H2

    NASA Astrophysics Data System (ADS)

    Leung, Anthony C. K.; Kirchner, Tom

    2016-05-01

    Charge exchange in C6 +-He and -H2 collisions followed by x-ray emission is examined using the two-center basis generator method for low to intermediate projectile energies. Within the independent electron model, we calculate capture cross sections and perform a radiative cascade analysis to obtain Lyman line-emission ratios. Single capture is considered for the C6 +-He system, while both single capture and autoionizing double capture are considered for the C6 +-H2 system. Effects of a time-dependent screening potential that models target response on the l distribution of capture cross sections and the line-emission ratios are examined as well. Calculated line-emission ratios based on the no-response approximation are in satisfactory agreement with previous measurements.

  4. Localization of the large-angle foil-scattering beam loss caused by the multiturn charge-exchange injection

    NASA Astrophysics Data System (ADS)

    Kato, Shinichi; Yamamoto, Kazami; Yoshimoto, Masahiro; Harada, Hiroyuki; Kinsho, Michikazu

    2013-07-01

    In the 3 GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex, significant losses were observed at the branching of the H0 dump line and the beam position monitor that was inserted downstream of the H0 dump branch duct. These losses were caused by the large-angle scattering of the injection and circulating beams at the charge-exchange foil. To realize high-power operation, these losses must be mitigated. Therefore, a new collimation system was developed and installed in October 2011. To efficiently optimize this system, the behavior of particles scattered by the foil and produced by the absorber were simulated, and the optimal position and angle of the absorber were investigated. During this process, an angle regulation method for the absorber was devised. An outline of this system, the angle regulation method for the absorber, and the performance of this new collimation system are described.

  5. The Ion-induced Charge-exchange X-ray Emission of the Jovian Auroras: Magnetospheric or Solar Wind Origin?

    SciTech Connect

    Hui, Yawei; Schultz, David Robert; Kharchenko, Vasili A; Stancil, Phillip C.; Cravens, Thomas E. E.; Lisse, Carey M.; Dalgarno, A.

    2009-01-01

    A new and more comprehensive model of charge-exchange induced X-ray emission, due to ions precipitating into the Jovian atmosphere near the poles, has been used to analyze spectral observations made by the Chandra X-ray Observatory. The model includes for the first time carbon ions, in addition to the oxygen and sulfur ions previously considered, in order to account for possible ion origins from both the solar wind and the Jovian magnetosphere. By comparing the model spectra with newly reprocessed Chandra observations, we conclude that carbon ion emission provides a negligible contribution, suggesting that solar wind ions are not responsible for the observed polar X-rays. In addition, results of the model fits to observations support the previously estimated seeding kinetic energies of the precipitating ions ( 0.7-2 MeV/u), but infer a different relative sulfur to oxygen abundance ratio for these Chandra observations.

  6. THE ION-INDUCED CHARGE-EXCHANGE X-RAY EMISSION OF THE JOVIAN AURORAS: MAGNETOSPHERIC OR SOLAR WIND ORIGIN?

    SciTech Connect

    Hui Yawei; Schultz, David R.; Kharchenko, Vasili A.; Stancil, Phillip C.; Cravens, Thomas E.; Lisse, Carey M. E-mail: schultzd@ornl.gov E-mail: stancil@physast.uga.edu E-mail: carey.lisse@jhuapl.edu

    2009-09-10

    A new and more comprehensive model of charge-exchange induced X-ray emission, due to ions precipitating into the Jovian atmosphere near the poles, has been used to analyze spectral observations made by the Chandra X-ray Observatory. The model includes for the first time carbon ions, in addition to the oxygen and sulfur ions previously considered, in order to account for possible ion origins from both the solar wind and the Jovian magnetosphere. By comparing the model spectra with newly reprocessed Chandra observations, we conclude that carbon ion emission provides a negligible contribution, suggesting that solar wind ions are not responsible for the observed polar X-rays. In addition, results of the model fits to observations support the previously estimated seeding kinetic energies of the precipitating ions ({approx}0.7-2 MeV u{sup -1}), but infer a different relative sulfur-to-oxygen abundance ratio for these Chandra observations.

  7. Optimization and application of cooled avalanche photodiodes for spectroscopic fluctuation measurements with ultra-fast charge exchange recombination spectroscopy

    NASA Astrophysics Data System (ADS)

    Truong, D. D.; Fonck, R. J.; McKee, G. R.

    2016-11-01

    The Ultra-Fast Charge Exchange Recombination Spectroscopy (UF-CHERS) diagnostic is a highly specialized spectroscopic instrument with 2 spatial channels consisting of 8 spectral channels each and a resolution of ˜0.25 nm deployed at DIII-D to measure turbulent ion temperature fluctuations. Charge exchange emissions are obtained between 528 and 530 nm with 1 μs time resolution to study plasma instabilities. A primary challenge of extracting fluctuation measurements from raw UF-CHERS signals is photon and electronic noise. In order to reduce dark current, the Avalanche Photodiode (APD) detectors are thermo-electrically cooled. State-of-the-art components are used for the signal amplifiers and conditioners to minimize electronic noise. Due to the low incident photon power (≤1 nW), APDs with a gain of up to 300 are used to optimize the signal to noise ratio. Maximizing the APDs' gain while minimizing the excess noise factor (ENF) is essential since the total noise of the diagnostic sets a floor for the minimum level of detectable broadband fluctuations. The APDs' gain should be high enough that photon noise dominates electronic noise, but not excessive so that the ENF overwhelms plasma fluctuations. A new generation of cooled APDs and optimized preamplifiers exhibits significantly enhanced signal-to-noise compared to a previous generation. Experiments at DIII-D have allowed for characterization and optimization of the ENF vs. gain. A gain of ˜100 at 1700 V is found to be near optimal for most plasma conditions. Ion temperature and toroidal velocity fluctuations due to the edge harmonic oscillation in quiescent H-mode plasmas are presented to demonstrate UF-CHERS' capabilities.

  8. Inclusive measurement of (p,. pi. /sup -/xn) double charge exchange reactions on bismuth from threshold to 800 MeV

    SciTech Connect

    Dombsky, M.; D'Auria, J.M.; Kelson, I.; Yavin, A.I.; Ward, T.E.; Clark, J.L.; Ruth, T.; Sheffer, G.

    1985-07-01

    The energy dependence of the total angle-integrated cross section for the production of astatine isotopes from (p,..pi../sup -/xn) double charge exchange reactions on bismuth (/sup 209/Bi) was measured from 120 to 800 MeV using activation and radiochemical techniques. Chemical yields were estimated by direct radioassaying of /sup 211/At activity in thin (approx.1 mg/cm/sup 2/), irradiated bismuth targets. Calculations of the contributions of secondary (two-step) reactions to these measured astatine yields were performed, based partially upon the observed /sup 211/At activity although even at the highest energies, the contribution to products lighter than /sup 207/At was negligible. These data for products with as many as seven neutrons removed from the doubly coherent product (/sup 210/At) display nearly Gaussian shapes for the mass distributions of the astatine residues, with the maximum occurring for about /sup 204/At. The most probable momentum transfer deduced from these distributions for the initial ..pi../sup -/ production step was 335 MeV/c. The observed excitation functions display a behavior similar to that observed for the yield of /sup 210/Po from a (p,..pi../sup 0/) reaction on /sup 209/Bi, but radically different from that observed for inclusive ..pi../sup -/ reactions on a heavy nucleus. These data are discussed in terms of recent theoretical approaches to negative pion production from bismuth. In addition, a simple, schematic model is developed to treat the rapidly decreasing percentage of the total inclusive ..pi../sup -/ emission which is observed for this double charge exchange reaction. This model reflects the opacity of a nucleus to a source of internal energetic protons.

  9. Magnetospheric Solar Wind Charge Exchange - A Comparison Between the GUMICS-4 MHD Model and XMM-Newton.

    NASA Astrophysics Data System (ADS)

    Walach, M. T.; Whittaker, I. C.; Sembay, S.; Carter, J. A.; Read, A. M.

    2015-12-01

    The Solar Wind Earth Exchange Project (SWEEP) seeks to improve our understanding of the interaction of the solar wind with the Earth. X-ray emission resulting from charge exchange between oxygen in the solar wind and magnetospheric neutral hydrogen is modelled for a series of observations from XMM-Newton, an X-ray astronomical observatory. We use OMNI solar wind conditions, heavy ion composition data from ACE, the Hodges neutral hydrogen model and combine these with the GUMICS-4 MHD model to predict the global levels of X-ray emission from solar wind charge exchange (in the 0.5-0.7 keV band). The emission is then integrated along a line of sight and compared to the measured XMM-Newton sky background emissivity rates to determine the accuracy of these model predictions. Our results show that the magnitude of the integrated X-ray emissivity for both the modelled and observed flux is similar in a large number of cases, while the correlation of emission changes in detail between cases. We show that the accuracy of the oxygen density and relative charge state abundances is vital. The positional accuracy of the magnetopause is important as it forms the outer edge of the masking of the plasmasphere, including the cusps in our global emissivity rates. The derived position of the magnetopause and various masks are discussed with examples given, highlighting their relative accuracy. We also show the potential of X-ray emission for remote sensing of the magnetosphere, when used in combination with a wide field X-ray imaging system.

  10. Use of the TFTR prototype charge exchange neutral analyzer for fast He/sub 3//sup + +/ diagnostics during ICRF heating on PLT

    SciTech Connect

    Medley, S.S.

    1981-07-01

    The Charge Exchange Neutral Analyzer (CENA) for TFTR is designed to measure singly charged ion species of atomic mass A = 1, 2, and 3 simultaneously with up to 75 energy channels per mass and an energy range of 0.5 < AE < 600, where AE is in units of AMU.keV. Plans to test the prototype analyzer on PLT prior to installation on TFTR are discussed. The capability of the analyzer to simultaneously measure singly reionized H, D, and He/sub 3/ charge exchange neutrals makes the analyzer of particular interest for recently proposed fast He/sub 3//sup + +/ diagnostics during ICRF heating on PLT.

  11. Electron-Nuclear Dynamics of atomic and molecular collisions: Charge exchange and energy loss

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, Remigio; Sabin, John R.; Ohrn, Yngve; Deumens, Erik

    2004-05-01

    Processes like electron exchange (capture and loss), bond breaking, and chemical reactions are difficult to visualize and treat in a time-independent approach. In this work, we present the Electron-Nuclear Dynamics (END) method for the study of time-dependent scattering processes. The END is a general approach for treating time-dependent problems which includes the dynamics of electrons and nuclei simultaneously by considering the full electron-nuclear coupling in the system and thus eliminates the necessity of constructing potential-energy surfaces. The theory approximates the time dependent Schrödinger equation starting from the time dependent variational principle (TDVP) by deriving a Hamiltonian dynamical system for time dependent nuclear and electronic wave function parameters. The wave function is described in a coherent state manifold, which leads to a system of Hamilton's equations of motion. The resulting system of coupled, first order, ordinary differential equations approximates the Schrödinger equation. A detailed analysis of the END equations is given for the case of a single-determinantal state for the electrons and a classical treatment of the nuclei. Emphasis is put on electron exchange, differential cross section and energy loss (stopping cross section) of collision of ions, atoms and molecules involving H, He, C, N, O, and Ne atoms. We compare our results to available experimental data.

  12. Asymptotic form of the charge exchange cross section in the three body rearrangement collisions

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1975-01-01

    A three body general rearrangement collision is considered where the initial and final bound states are described by the hydrogen-like wave functions. Mathematical models are developed to establish the relationships of quantum number, the reduced mass, and the nuclear charge of the final state. It is shown that for the low lying levels, the reciprocal of n cubed scaling law at all incident energies is only approximately satisfied. The case of the symmetric collisions is considered and it is shown that for high n and high incident energy, E, the cross section behaves as the reciprocal of E cubed. Zeros and minima in the differential cross sections in the limit of high n for protons on atomic hydrogen and positrons on atomic hydrogen are given.

  13. Electron-Nuclear Dynamics of collision processes: Charge exchange and energy loss

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, Remigio; Sabin, John R.; Öhrn, Yngve; Deumens, Erik

    2004-03-01

    We present the Electron-Nuclear Dynamics (END) method for the study of time-dependent scattering processes. The END is a general approach for treating time-dependent problems which includes the dynamics of electrons and nuclei simultaneously by considering the full electron-nuclear coupling in the system and thus eliminates the necessity of constructing potential-energy surfaces. The theory approximates the time dependent Schrödinger equation starting from the time dependent variational principle by deriving a Hamiltonian dynamical system for time dependent nuclear and electronic wave function parameters. The wave function is described in a coherent state manifold, which leads to a system of Hamilton's equations of motion. Emphasis is put on electron exchange, differential cross section and energy loss (stopping cross section) of collision of ions, atoms and molecules involving H, He, C, N, O, and Ne atoms. We compare our results to available experimental data.

  14. New Measurements of the Solar Wind Charge Exchange, Local Bubble, and Halo 3/4 keV Emission from XMM-Newton and Suzaku Shadowing Observations

    NASA Astrophysics Data System (ADS)

    Shelton, Robin L.; Henley, David

    2016-06-01

    We report on the analyses of XMM-Newton and/or Suzaku observations of 6 on-cloud and off-cloud shadowing pairs. This study provides the first analysis of two of these pairs and the first uniform analysis of the larger dataset. For every shadowing pair, we determined the foreground and halo components by simultaneously fitting the spectra from both members of the pair with a model that included a foreground component and an absorbed background component. In the past, foreground X-ray emission was thought to come from the Local Bubble of hot gas surrounding the solar neighborhood and so thermal spectral models were used. Now that solar wind charge exchange is recognized as a source of foreground X-ray photons, it is appropriate to consider charge exchange models as well. For this reason, we repeated the analyses using one of 3 possible foreground models: a charge exchange spectral model whose line ratios come from atomic physics calculations and are presented in Cumbee et al. (2014), a charge exchange model based on the AtomDB Charge Exchange code, or a thermal spectrum. The analyses of the larger dataset enabled us to place an upper limit on the Local Bubble's O VII contribution, provide measurements of the local and halo contributions in the 0.4 to 1.0 keV band, comment on the abilities of the various solar wind models to fit the data, and comment on the sensitivity of the fit parameters to the choice of foreground model, metal abundance tables, and X-ray observatory.

  15. Electron collisions with phenol: Total, integral, differential, and momentum transfer cross sections and the role of multichannel coupling effects on the elastic channel

    NASA Astrophysics Data System (ADS)

    da Costa, Romarly F.; de Oliveira, Eliane M.; Bettega, Márcio H. F.; Varella, Márcio T. do N.; Jones, Darryl B.; Brunger, Michael J.; Blanco, Francisco; Colmenares, Rafael; Limão-Vieira, Paulo; García, Gustavo; Lima, Marco A. P.

    2015-03-01

    We report theoretical and experimental total cross sections for electron scattering by phenol (C6H5OH). The experimental data were obtained with an apparatus based in Madrid and the calculated cross sections with two different methodologies, the independent atom method with screening corrected additivity rule (IAM-SCAR), and the Schwinger multichannel method with pseudopotentials (SMCPP). The SMCPP method in the Nopen-channel coupling scheme, at the static-exchange-plus-polarization approximation, is employed to calculate the scattering amplitudes at impact energies ranging from 5.0 eV to 50 eV. We discuss the multichannel coupling effects in the calculated cross sections, in particular how the number of excited states included in the open-channel space impacts upon the convergence of the elastic cross sections at higher collision energies. The IAM-SCAR approach was also used to obtain the elastic differential cross sections (DCSs) and for correcting the experimental total cross sections for the so-called forward angle scattering effect. We found a very good agreement between our SMCPP theoretical differential, integral, and momentum transfer cross sections and experimental data for benzene (a molecule differing from phenol by replacing a hydrogen atom in benzene with a hydroxyl group). Although some discrepancies were found for lower energies, the agreement between the SMCPP data and the DCSs obtained with the IAM-SCAR method improves, as expected, as the impact energy increases. We also have a good agreement among the present SMCPP calculated total cross section (which includes elastic, 32 inelastic electronic excitation processes and ionization contributions, the latter estimated with the binary-encounter-Bethe model), the IAM-SCAR total cross section, and the experimental data when the latter is corrected for the forward angle scattering effect [Fuss et al., Phys. Rev. A 88, 042702 (2013)].

  16. Electron collisions with phenol: Total, integral, differential, and momentum transfer cross sections and the role of multichannel coupling effects on the elastic channel

    SciTech Connect

    Costa, Romarly F. da; Oliveira, Eliane M. de; Lima, Marco A. P.; Bettega, Márcio H. F.; Varella, Márcio T. do N.; Jones, Darryl B.; Brunger, Michael J.; Blanco, Francisco; Colmenares, Rafael; and others

    2015-03-14

    We report theoretical and experimental total cross sections for electron scattering by phenol (C{sub 6}H{sub 5}OH). The experimental data were obtained with an apparatus based in Madrid and the calculated cross sections with two different methodologies, the independent atom method with screening corrected additivity rule (IAM-SCAR), and the Schwinger multichannel method with pseudopotentials (SMCPP). The SMCPP method in the N{sub open}-channel coupling scheme, at the static-exchange-plus-polarization approximation, is employed to calculate the scattering amplitudes at impact energies ranging from 5.0 eV to 50 eV. We discuss the multichannel coupling effects in the calculated cross sections, in particular how the number of excited states included in the open-channel space impacts upon the convergence of the elastic cross sections at higher collision energies. The IAM-SCAR approach was also used to obtain the elastic differential cross sections (DCSs) and for correcting the experimental total cross sections for the so-called forward angle scattering effect. We found a very good agreement between our SMCPP theoretical differential, integral, and momentum transfer cross sections and experimental data for benzene (a molecule differing from phenol by replacing a hydrogen atom in benzene with a hydroxyl group). Although some discrepancies were found for lower energies, the agreement between the SMCPP data and the DCSs obtained with the IAM-SCAR method improves, as expected, as the impact energy increases. We also have a good agreement among the present SMCPP calculated total cross section (which includes elastic, 32 inelastic electronic excitation processes and ionization contributions, the latter estimated with the binary-encounter-Bethe model), the IAM-SCAR total cross section, and the experimental data when the latter is corrected for the forward angle scattering effect [Fuss et al., Phys. Rev. A 88, 042702 (2013)].

  17. Combined experimental and theoretical study on the differential elastic scattering cross sections for acetone by electron impact energy of 7.0-50 eV

    NASA Astrophysics Data System (ADS)

    Pastega, D. F.; Lange, E.; Ameixa, J.; Barbosa, A. S.; Blanco, F.; García, G.; Bettega, M. H. F.; Limão-Vieira, P.; Ferreira da Silva, F.

    2016-03-01

    We report elastic differential cross sections (DCSs) for electron interactions with acetone, C3H6O . The incident electron energy range was 7.0-50 eV, and the scattered electron angular range for the differential measurements varied from 10° to 120°. The calculated cross sections were obtained with two different methodologies, the Schwinger multichannel method with pseudopotentials (SMCPP), and the independent-atom method with screening-corrected additivity rule (IAM-SCAR). The present elastic DCSs have been found to agree well with the results of IAM-SCAR calculations above 20 eV, and also with the SMC calculations below 30 eV. Although some discrepancies were found for lower energies, the agreement between the SMCPP data and the DCSs obtained with the IAM-SCAR method improves, as expected, as the impact energy increases. Comparison with previous DCSs shows good agreement albeit the present data is extended down to lower electron impact energies. We find a low-lying π* shape resonance located at 2.6 eV, in agreement with recent results on electron collisions with acetone [M. G. P. Homem et al., Phys. Rev. A 92, 032711 (2015), 10.1103/PhysRevA.92.032711]. The presence of a σ* resonance is also discussed.

  18. Evidence for Non-Exponential Differential Cross-Section of pp Elastic Scattering at Low |t| and √s = 8 TeV by TOTEM

    NASA Astrophysics Data System (ADS)

    Csörgő, T.

    2016-07-01

    Recently published and preliminary results of the TOTEM experiment are presented, emphasizing a recent discovery of a non-exponential behaviour of the differential crosssection of elastic proton-proton scattering, that TOTEM measured with an unprecedented precision at the centre-of-mass energy √s = 8 TeV based on a high-statistics data sample obtained with the β* = 90 m optics of CERN LHC. Both the statistical and systematic uncertainties remained below 1%, except for the t-independent contribution from the overall normalisation. This measurement allowed TOTEM to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027 < |t| < 0.2 GeV2 with a significance greater than 7σ. In this context we also highlight the innovative TOTEM recalibration of LHC optics, that used elastic scattering data measured by the world's largest and most complex Roman Pot detector system, and discuss recent preliminary TOTEM data on the Coulomb-Nuclear interference region with its physics implications.

  19. A Combined Desorption Ionization by Charge Exchange (DICE) and Desorption Electrospray Ionization (DESI) Source for Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Chan, Chang-Ching; Bolgar, Mark S.; Miller, Scott A.; Attygalle, Athula B.

    2011-01-01

    A source that couples the desorption ionization by charge exchange (DICE) and desorption electrospray ionization (DESI) techniques together was demonstrated to broaden the range of compounds that can be analyzed in a single mass spectrometric experiment under ambient conditions. A tee union was used to mix the spray reagents into a partially immiscible blend before this mixture was passed through a conventional electrospray (ES) probe capillary. Using this technique, compounds that are ionized more efficiently by the DICE method and those that are ionized better with the DESI procedure could be analyzed simultaneously. For example, hydroquinone, which is not detected when subjected to DESI-MS in the positive-ion generation mode, or the sodium adduct of guaifenesin, which is not detected when examined by DICE-MS, could both be detected in one experiment when the two techniques were combined. The combined technique was able to generate the molecular ion, proton and metal adduct from the same compound. When coupled to a tandem mass spectrometer, the combined source enabled the generation of product ion spectra from the molecular ion and the [M + H]+ or [M + metal]+ ions of the same compound without the need to physically change the source from DICE to DESI. The ability to record CID spectra of both the molecular ion and adduct ions in a single mass spectrometric experiment adds a new dimension to the array of mass spectrometric methods available for structural studies.

  20. Modeling the magnetospheric X-ray emission from solar wind charge exchange with verification from XMM-Newton observations

    NASA Astrophysics Data System (ADS)

    Whittaker, Ian C.; Sembay, Steve; Carter, Jennifer A.; Read, Andrew M.; Milan, Steve E.; Palmroth, Minna

    2016-05-01

    An MHD-based model of terrestrial solar wind charge exchange (SWCX) is created and compared to 19 case study observations in the 0.5-0.7 keV emission band taken from the European Photon Imaging Cameras on board XMM-Newton. This model incorporates the Global Unified Magnetosphere-Ionosphere Coupling Simulation-4 MHD code and produces an X-ray emission datacube from O7+ and O8+ emission lines around the Earth using in situ solar wind parameters as the model input. This study details the modeling process and shows that fixing the oxygen abundances to a constant value reduces the variance when comparing to the observations, at the cost of a small accuracy decrease in some cases. Using the ACE oxygen data returns a wide ranging accuracy, providing excellent correlation in a few cases and poor/anticorrelation in others. The sources of error for any user wishing to simulate terrestrial SWCX using an MHD model are described here and include mask position, hydrogen to oxygen ratio in the solar wind, and charge state abundances. A dawn-dusk asymmetry is also found, similar to the results of empirical modeling. Using constant oxygen parameters, magnitudes approximately double that of the observed count rates are returned. A high accuracy is determined between the model and observations when comparing the count rate difference between enhanced SWCX and quiescent periods.

  1. The velocity dependence of X-ray emission due to Charge Exchange: Applications in the Cygnus Loop

    NASA Astrophysics Data System (ADS)

    Cumbee, Renata; Lyons, David; Mullen, Patrick; Shelton, Robin L.; Stancil, Phillip C.; Schultz, David R.

    2016-04-01

    The fundamental collisional process of charge exchange (CX) has been been established as a primary source of X-ray emission from the heliosphere [1], planetary exospheres [2], and supernova remnants [3,4]. In this process, X-ray emission results from the capture of an electron by a highly charged ion from a neutral atom or molecule, to form a highly-excited, high charge state ion. As the captured electron cascades down to the lowest energy level, photons are emitted, including X-rays.To provide reliable CX-induced X-ray spectral models to realistically simulate high-energy astrophysical environments, line ratios and spectra are computed using theoretical CX cross-sections obtained with the multi-channel Landau-Zener, atomic-orbital close-coupling, and classical-trajectory Monte Carlo methods for various collisional velocities. Collisions of bare and H-like C to Al ions with H, He, and H2 are considered. Using these line ratios, XSPEC models of CX emission in the northeast rim of the Cygnus Loop supernova remnant will be shown as an example with ion velocity dependence.[1] Henley, D. B. & Shelton, R. L. 2010, ApJSS, 187, 388[2] Dennerl, K. et al. 2002, A&A 386, 319[3] Katsuda, S. et al. 2011, ApJ 730 24[4] Cumbee, R. S. et al. 2014, ApJ 787 L31

  2. Compact multichannel neutral particle analyzer for measurement of energetic charge-exchanged neutrals in Alcator C-Mod

    SciTech Connect

    Tang, V.; Liptac, J.; Parker, R. R.; Bonoli, P. T.; Fiore, C. L.; Granetz, R. S.; Irby, J. H.; Lin, Y.; Wukitch, S. J.; Frenje, J. A.; Leiter, R.; Mcduffee, S.; Petrasso, R. D.

    2006-08-15

    A four-channel compact neutral particle analyzer (CNPA) based on operating small Si diode detectors in pulse-height analysis (PHA) mode is used to measure energetic hydrogen minority ions with energies between {approx}50 and 350 keV stemming from ion-cyclotron range-of-frequency heated D(H) Alcator C-Mod plasmas with both active and passive charge exchange (CX). First core minority ion distribution results from Alcator C-Mod discharges and a detailed description of the diagnostic are presented. The diagnostic employs integrated electronics and fast digitization of the shaping amplifier voltage. The digitized data are stored for postshot PHA, which removes the constraints of real-time PHA and allows for improved performance via elimination of base line shift effects and potentially relieving pileup through Gaussian fitting routines. The CNPA is insensitive to the large gamma and neutron background in Alcator C-Mod discharges but is susceptible to the plasma's soft x-ray flux. The soft x-ray flux limits the CNPA energy resolution to {approx}15-20 keV. A simple model is used to interpret the active CNPA data which permits rapid estimates of the core hydrogen minority temperatures and anisotropy with a time resolution of {approx}100 ms. Hydrogenlike boron is identified as an important electron donor for the CX signal.

  3. Analysis of x-ray emission in charge-exchange collisions of C6+ ions with He and H2

    NASA Astrophysics Data System (ADS)

    Leung, Anthony C. K.; Kirchner, T.

    2016-05-01

    Charge exchange in C6+-He and - H2 collisions followed by x-ray emission is examined using the two-center basis generator method within the independent electron model. The analysis examines the two collision systems for low to intermediate projectile energies. We perform capture cross section and radiative cascade calculations to obtain Lyman line emission ratios which can be compared to measurements that were carried out at the Oak Ridge National Laboratory Multicharged Ion Research Facility. Single-electron capture is considered for the C6+-He system while both single and autoionizing double capture are considered for the C6+- H2 system. We also examine the effects of a time-dependent screening potential that models target response on the l distribution of the capture cross sections and the emission ratios. Calculated line emission ratios based on the no-response approximation are found to be in satisfactory agreement with the measurements. Work supported by SHARCNET, OGS, and NSERC, Canada

  4. Charge state distributions and charge exchange cross sections of carbon in helium at 30-258 keV

    NASA Astrophysics Data System (ADS)

    Maxeiner, Sascha; Seiler, Martin; Suter, Martin; Synal, Hans-Arno

    2015-10-01

    With the introduction of helium stripping in radiocarbon (14C) accelerator mass spectrometry (AMS), higher +1 charge state yields in the 200 keV region and fewer beam losses are observed compared to nitrogen or argon stripping. To investigate the feasibility of even lower beam energies for 14C analyses the stripping characteristics of carbon in helium need to be further studied. Using two different AMS systems at ETH Zurich (myCADAS and MICADAS), ion beam transmissions of carbon ions for the charge states -1, +1, +2 and +3 were measured in the range of 258 keV down to 30 keV. The correction for beam losses and the extraction of charge state yields and charge exchange cross sections will be presented. An increase in population of the +1 charge state towards the lowest measured energies up to 75% was found as well as agreement with previous data from literature. The findings suggest that more compact radiocarbon AMS systems are possible and could provide even higher efficiency than current systems operating in the 200 keV range.

  5. Measurements of the total atomic differential cross section of elastic scattering of 59.54-keV photons

    NASA Astrophysics Data System (ADS)

    Casnati, E.; Baraldi, C.; Tartari, A.

    1990-09-01

    Accurate measurements, mostly to within 2%, of the total atomic cross section for the elastic scattering of 59.54-keV photons on atoms in the 13<=Z<=82 range were carried out at 60°, 90°, and 120° scattering angles. Very good agreement with other experimental data was observed, in particular, with those of Schumacher and Stoffregen [Z. Phys. A 283, 15 (1977)]. The comparison with the theoretical results given by Kissel and co-workers [Phys. Rev. A 22, 1979 (1980); Phys. Rep. 140, 75 (1986)] confirms the validity of their procedure within the value intervals explored.

  6. Integrin activation and internalization on soft ECM as a mechanism of induction of stem cell differentiation by ECM elasticity

    PubMed Central

    Du, Jing; Chen, Xiaofei; Liang, Xudong; Zhang, Guangyao; Xu, Jia; He, Linrong; Zhan, Qingyuan; Feng, Xi-Qiao; Chien, Shu; Yang, Chun

    2011-01-01

    The mechanism by which ECM elasticity induces lineage specification of stem cells has not been clearly understood. Integrins are well-documented mechanosensors that are positioned at the beginning of the sensing pathway. By using an antibody specifically recognizing the active conformation of β1 integrin, we observed that β1 integrin activation in bone marrow mesenchymal stem cells (BMMSCs) was induced by soft substrate to a significantly greater degree than by stiff substrate. In contrast, however, the level of cell surface integrin on soft substrate was significantly lower than that on stiff substrate. Soft substrate markedly enhanced the internalization of integrin, and this internalization was mediated mainly through caveolae/raft-dependent endocytosis. The inhibition of integrin internalization blocked the neural lineage specification of BMMSCs on soft substrate. Furthermore, soft substrate also repressed the bone morphogenetic protein (BMP)/Smad pathway at least partially through integrin-regulated BMP receptor endocytosis. A theoretical analysis based on atomic force microscopy (AFM) data indicated that integrin–ligand complexes are more easily ruptured on soft substrate; this outcome may contribute to the enhancement of integrin internalization on soft substrate. Taken together, our results suggest that ECM elasticity affects integrin activity and trafficking to modulate integrin BMP receptor internalization, thus contributing to stem cell lineage specification. PMID:21593411

  7. Cross section for Rydberg antihydrogen production via charge exchange between Rydberg positroniums and antiprotons in a magnetic field

    NASA Astrophysics Data System (ADS)

    Krasnický, D.; Caravita, R.; Canali, C.; Testera, G.

    2016-08-01

    The antihydrogen formation by charge exchange between cold antiprotons and Rydberg positronium Ps* is studied by using the classical trajectory Monte Carlo method. In the absence of external magnetic field the cross section scaled by the fourth power of the Ps* principal quantum number nPs shows a universal behavior as a function of the ratio kv between the velocity of the Ps center of mass and that of the positron in the classical circular orbit. At low velocity, below about kv≃0.2 -0.3 , we show for Rydberg positronium that the cross section increases as 1 /kv2 or, in an equivalent way, as 1 /EPs cm with EPs cm being the Ps* center-of-mass energy. In this regime the distribution of the principal quantum number of the antihydrogen state is narrow and it shows a peak at about √{2}nPs while at higher kv values a broad distribution of antihydrogen states is produced. The study of the collision process in the presence of moderate magnetic field (0.5-2 T) shows that there is an experimentally interesting region of kv with the cross section slightly higher than that in the absence of field. However the presence of a magnetic field changes significantly the cross section behavior as a function of kv, especially at low velocities, where reductions of the cross sections and deviations from the 1 /kv2 (1 /EPs cm) are observed. Our calculations show a dependance of the cross section upon the angle between the magnetic field and the flight direction of the incoming Ps*.

  8. X-Ray Emission Cross Sections following Charge Exchange by Multiply-Charged Ions of Astrophysical Interest

    SciTech Connect

    Otranto, S; Olson, R E; Beiersdorfer, P

    2005-09-19

    State selective nl-electron capture cross sections are presented for highly charged ions with Z = 6-10 colliding with atoms and molecules. The energy range investigated was from 1 eV/amu (v = 0.006 a.u.) to 100 keV/amu (v =2.0 a.u.). The energy dependence of the l-level populations is investigated. The K-shell x-ray emission cross sections are determined by using the calculated state-selective electron capture results as input and then applying hydrogenic branching and cascading values for the photon emission. A major shift in the line emission from being almost solely Lyman-{alpha} transitions at the highest collisions energies to strong high-n to 1s transitions at the lowest energies is observed. The calculated cross sections are in reasonable accord with measurements made by Greenwood et al, Phys. Rev. A 63, 062707 (2001), using O{sup 8+} and Ne{sup 10+} on various targets at 3 keV/amu. The calculations are also in accord with x-ray emission cross section data obtained on the EBIT machine at LLNL where O{sup 8+} and Ne{sup 10+} high resolution measurements were made at a temperature of 10 eV/amu for a series of targets with varying ionization potentials. The Ne{sup 10+} data clearly shows the contribution from multiple capture followed by Auger autoionization in the line emission spectra. Our calculated line emission cross sections are used to provide an ab initio determination of the soft x-ray spectrum of comet C/Linear 1999 S4 that was observed on the Chandra X-ray Observatory. The calculations show that the spectrum is due to charge exchange of the neutral gases in the comet's coma with the ions of the slow solar wind.

  9. Charge Exchange-induced X-Ray Emission of Fe xxv and Fe xxvI via a Streamlined Model

    NASA Astrophysics Data System (ADS)

    Mullen, P. D.; Cumbee, R. S.; Lyons, D.; Stancil, P. C.

    2016-06-01

    Charge exchange (CX) is an important process for the modeling of X-ray spectra obtained by the Chandra, XMM-Newton, and Suzaku X-ray observatories, as well as the anticipated Astro-H mission. The understanding of the observed X-ray spectra produced by many astrophysical environments is hindered by the current incompleteness of available atomic and molecular data—especially for CX. Here, we implement a streamlined program set that applies quantum defect methods and the Landau-Zener theory to generate total, n-resolved, and n{\\ell }S-resolved cross sections for any given projectile ion/target CX collision. By using these data in a cascade model for X-ray emission, theoretical spectra for such systems can be predicted. With these techniques, Fe25+ and Fe26+ CX collisions with H, He, H2, N2, H2O, and CO are studied for single-electron capture (SEC). These systems have been selected because they illustrate computational difficulties for high projectile charges. Furthermore, Fe xxv and Fe xxvi emission lines have been detected in the Galactic center and Galactic ridge. Theoretical X-ray spectra for these collision systems are compared to experimental data generated by an electron-beam ion trap study. Several ℓ-distribution models have been tested for Fe25+ and Fe26+ SEC. Such analyses suggests that commonly used ℓ-distribution models struggle to accurately reflect the true distribution of electron capture as understood by more advanced theoretical methods.

  10. Core-ion temperature measurement of the ADITYA tokamak using passive charge exchange neutral particle energy analyzer

    SciTech Connect

    Pandya, Santosh P.; Ajay, Kumar; Mishra, Priyanka; Dhingra, Rajani D.; Govindarajan, J.

    2013-02-15

    Core-ion temperature measurements have been carried out by the energy analysis of passive charge exchange (CX) neutrals escaping out of the ADITYA tokamak plasma (minor radius, a= 25 cm and major radius, R= 75 cm) using a 45 Degree-Sign parallel plate electrostatic energy analyzer. The neutral particle analyzer (NPA) uses a gas cell configuration for re-ionizing the CX-neutrals and channel electron multipliers (CEMs) as detectors. Energy calibration of the NPA has been carried out using ion-source and {Delta}E/E of high-energy channel has been found to be {approx}10%. Low signal to noise ratio (SNR) due to VUV reflections on the CEMs was identified during the operation of the NPA with ADITYA plasma discharges. This problem was rectified by upgrading the system by incorporating the additional components and arrangements to suppress VUV radiations and improve its VUV rejection capabilities. The noise rejection capability of the NPA was experimentally confirmed using a standard UV-source and also during the plasma discharges to get an adequate SNR (>30) at the energy channels. Core-ion temperature T{sub i}(0) during flattop of the plasma current has been measured to be up to 150 eV during ohmically heated plasma discharges which is nearly 40% of the average core-electron temperature (typically T{sub e}(0) {approx} 400 eV). The present paper describes the principle of tokamak ion temperature measurement, NPA's design, development, and calibration along with the modifications carried out for minimizing the interference of plasma radiations in the CX-spectrum. Performance of the NPA during plasma discharges and experimental results on the measurement of ion-temperature have also been reported here.

  11. Multifluid Modeling of the Partially Ionized Chromosphere with Effects of Impact Ionization, Radiative Recombination and Charge Exchange

    NASA Astrophysics Data System (ADS)

    Maneva, Y. G.; Poedts, D. S.; Alvarez Laguna, A.; Lani, A.

    2015-12-01

    Neutrals play an important role in the evolution of the weakly ionized solar chromosphere where the number density of neutrals can vastly exceed the number density of protons. Therefore modeling the neutral-ion interactions and studying the effect of neutrals on the ambient plasma properties is an important task for better understanding the observed emission lines and the propagation of disturbances from the photosphere to the transition region and the corona. To pursue this goal we have developed two-fluid and three-fluid simulation setups to study the interaction between electrons, ions and neutrals in a reactive gravitationally stratified collisional media. The model considers the electrons and ions within the resistive MHD approach with Coulomb collisions and anisotropic heat flux determined by Braginskii's transport coefficients. The electromagnetic fields are evolved according to the full Maxwell equations, allowing for propagation of higher frequency waves neglected by the standard MHD approximation. Separate mass, momentum and energy conservation equations are considered for the neutrals and the interaction between the different fluids is determined by the chemical reactions, such as impact ionization, radiative recombination and charge exchange, provided as additional source terms. To initialize the system we consider an ideal gas equation of state with equal initial temperatures for the electrons, ions and the neutrals and different density profiles. The initial temperature and density profiles are height-dependent and follow VAL C atmospheric model for the solar chromosphere. We have searched for a chemical and collisional equilibrium between the ions and the neutrals in the hydrostatic case to avoid unphysical outflows and artificial heating induced by initial pressure imbalances. Next we consider ion-neutral interactions in magnetized plasma with an initial magnetic profile, corresponding to emerging magnetic funnel. Finally we include an external

  12. Structure-property relationships in non-epitaxial chalcogenide heterostructures: the role of interface density on charge exchange

    NASA Astrophysics Data System (ADS)

    Bauers, S. R.; Ditto, J.; Moore, D. B.; Johnson, D. C.

    2016-07-01

    A homologous series of quasi-2D ([PbSe]1+δ)m(TiSe2)m nanolayered heterostructures are prepared via self-assembly of designed precursors with 1 <= m <= 4 and their structures and properties investigated. All heterostructures have the same global composition but vary in their interface density. X-ray diffraction and electron microscopy studies show that the structures consist of rock salt structured PbSe layers alternating with TiSe2 layers, and that grain size increases with m. The compounds are all metallic with upturns in resistivity at low temperature suggesting electron localization, with room temperature resistivity of 1-3 10-5 Ω m, negative Hall coefficients and Seebeck coefficients between -50 and -100 μV K-1. A decrease in the mobile carrier concentration with temperature is observed for all m and the rate increases with increasing low-dimensionality. Decreasing the interface density also decreases the average carrier concentration while increasing the electron mobility. The Seebeck coefficients systematically increase in magnitude as m is increased, but the net effect to the power factor is small due to a compensating increase in resistivity. The observed transport behavior is not described by the simple rigid band models with charge transfer between constituents used previously. Charge exchange between constituents stabilizes the intergrowth, but also introduces mobile carriers and interfacial band bending that must play a role in the transport behavior of the heterostructures. As chemical potentials equilibrate in high m heterostructures there is a decrease in total coulombic stabilization as there are fewer interfaces, so m = 1 is likely to be most stable. This rationalizes why the structurally similar misfit layer compounds with m = 1 are often the only intergrowths that can be prepared. Charge transfer and band bending at interfaces should occur in other heterostructures with similar type II broken-gap band alignments and are important

  13. Cross section for Rydberg antihydrogen production via charge exchange between Rydberg positroniums and antiprotons in a magnetic field

    NASA Astrophysics Data System (ADS)

    Krasnický, D.; Caravita, R.; Canali, C.; Testera, G.

    2016-08-01

    The antihydrogen formation by charge exchange between cold antiprotons and Rydberg positronium Ps* is studied by using the classical trajectory Monte Carlo method. In the absence of external magnetic field the cross section scaled by the fourth power of the Ps* principal quantum number nPs shows a universal behavior as a function of the ratio kv between the velocity of the Ps center of mass and that of the positron in the classical circular orbit. At low velocity, below about kv≃0.2 -0.3 , we show for Rydberg positronium that the cross section increases as 1 /kv2 or, in an equivalent way, as 1 /EPs cm with EPs cm being the Ps* center-of-mass energy. In this regime the distribution of the principal quantum number of the antihydrogen state is narrow and it shows a peak at about √{2}nPs while at higher kv values a broad distribution of antihydrogen states is produced. The study of the collision process in the presence of moderate magnetic field (0.5-2 T) shows that there is an experimentally interesting region of kv with the cross section slightly higher than that in the absence of field. However the presence of a magnetic field changes significantly the cross section behavior as a function of kv, especially at low velocities, where reductions of the cross sections and deviations from the 1 /kv2 (1 /EPs cm) are observed. Our calculations show a dependance of the cross section upon the angle between the magnetic field and the flight direction of the incoming Ps*.

  14. Evidence for non-exponential elastic proton-proton differential cross-section at low |t| and $\\sqrt{s}$ = 8 TeV by TOTEM

    SciTech Connect

    Antchev, G.

    2015-08-15

    The TOTEM experiment has made a precise measurement of the elastic proton–proton differential cross-section at the centre-of-mass energy √s = 8 TeV based on a high-statistics data sample obtained with the β* = 90 m optics. Both the statistical and systematic uncertainties remain below 1%, except for the t -independent contribution from the overall normalisation. This unprecedented precision allows to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027 < |t| < 0.2 GeV2 with a significance greater than 7 σ. Two extended parametrisations, with quadratic and cubic polynomials in the exponent, are shown to be well compatible with the data. As a result, using them for the differential cross-section extrapolation to t=0, and further applying the optical theorem, yields total cross-section estimates of (101.5 ± 2.1) mb and (101.9 ± 2.1) mb, respectively, in agreement with previous TOTEM measurements.

  15. Evidence for non-exponential elastic proton-proton differential cross-section at low |t| and $$\\sqrt{s}$$ = 8 TeV by TOTEM

    DOE PAGESBeta

    Antchev, G.

    2015-08-15

    The TOTEM experiment has made a precise measurement of the elastic proton–proton differential cross-section at the centre-of-mass energy √s = 8 TeV based on a high-statistics data sample obtained with the β* = 90 m optics. Both the statistical and systematic uncertainties remain below 1%, except for the t -independent contribution from the overall normalisation. This unprecedented precision allows to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027 < |t| < 0.2 GeV2 with a significance greater than 7 σ. Two extended parametrisations, with quadratic and cubic polynomials in the exponent, are shown tomore » be well compatible with the data. As a result, using them for the differential cross-section extrapolation to t=0, and further applying the optical theorem, yields total cross-section estimates of (101.5 ± 2.1) mb and (101.9 ± 2.1) mb, respectively, in agreement with previous TOTEM measurements.« less

  16. The differential association of kidney dysfunction with small and large arterial elasticity: the multiethnic study of atherosclerosis.

    PubMed

    Peralta, Carmen A; Katz, Ronit; Madero, Magdalena; Sarnak, Mark; Kramer, Holly; Criqui, Michael H; Shlipak, Michael G

    2009-03-15

    Vascular remodeling may be a mechanism linking chronic kidney disease to cardiovascular disease. Whether early kidney dysfunction is associated with small and large arterial remodeling is not well understood. Using multivariable linear regression, back-transforming beta-coefficients to relative difference, the authors studied the association of cystatin C, creatinine-based estimated glomerular filtration rate (GFR), and albuminuria with small (SAE) and large (LAE) arterial elasticity and aortic distensibility among 6,282 participants in the Multiethnic Study of Atherosclerosis at baseline (2000-2002). Compared with the lowest quintile, higher quintiles of cystatin C were incrementally associated with lower SAE: third quintile relative difference = -5% (95% confidence interval (CI): -8, -2); fourth quintile relative difference = -10% (95% CI: -13, -8); and highest quintile relative difference = -16% (95% CI: -20, -12). By use of creatinine, the association was observed only among those with chronic kidney disease (estimated GFR, <60 mL/minute/1.73 m(2)): relative difference = -9% (95% CI: -13, -4). Albuminuria was significantly associated with lower SAE: relative difference = -6% (95% CI: -10, -1). Cystatin C was associated with lower LAE only at the highest quintile (relative difference = -3%, 95% CI: -6, 0) compared with the lowest quintile. By use of creatinine, chronic kidney disease was not independently associated with LAE (P = 0.912). Cystatin C, estimated GFR, and albuminuria were not associated with aortic distensibility (P = 0.26, 0.48, 0.45). Early kidney dysfunction is significantly associated with decreased arterial elasticity in smaller arteries and, to a lesser degree, in larger arteries.

  17. Measurement of the differential cross section dσ/dt in elastic pp¯ scattering at s=1.96TeV

    NASA Astrophysics Data System (ADS)

    Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G. A.; Aoki, M.; Askew, A.; Atkins, S.; Augsten, K.; Avila, C.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Barreto, J.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Bean, A.; Begalli, M.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besançon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatia, S.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Boos, E. E.; Borissov, G.; Bose, T.; Brandt, A.; Brandt, O.; Brock, R.; Brooijmans, G.; Bross, A.; Brown, D.; Brown, J.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Buszello, C. P.; Camacho-Pérez, E.; Carvalho, W.; Casey, B. C. K.; Castilla-Valdez, H.; Caughron, S.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chapon, E.; Chen, G.; Chevalier-Théry, S.; Cho, D. K.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M.-C.; Croc, A.; Cutts, D.; Das, A.; Davies, G.; de Jong, S. J.; De La Cruz-Burelo, E.; De Oliveira Martins, C.; Déliot, F.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; Dominguez, A.; Dubey, A.; Dudko, L. V.; Duggan, D.; Duperrin, A.; Dutt, S.; Dyshkant, A.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, A.; Evdokimov, V. N.; Facini, G.; Feng, L.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Garcia-Bellido, A.; García-González, J. A.; García-Guerra, G. A.; Gavrilov, V.; Gay, P.; Geng, W.; Gerbaudo, D.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Goussiou, A.; Grannis, P. D.; Greder, S.; Greenlee, H.; Gregores, E. M.; Grenier, G.; Gris, Ph.; Grivaz, J.-F.; Grohsjean, A.; Grünendahl, S.; Grünewald, M. W.; Guillemin, T.; Gutierrez, G.; Gutierrez, P.; Haas, A.; Hagopian, S.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hohlfeld, M.; Howley, I.; Hubacek, Z.; Hynek, V.; Iashvili, I.; Ilchenko, Y.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffré, M.; Jayasinghe, A.; Jesik, R.; Johns, K.; Johnson, E.; Johnson, M.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; Juste, A.; Kaadze, K.; Kajfasz, E.; Karmanov, D.; Kasper, P. A.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Kiselevich, I.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kulikov, S.; Kumar, A.; Kupco, A.; Kurča, T.; Kuzmin, V. A.; Lammers, S.; Landsberg, G.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lellouch, J.; Li, H.; Li, L.; Li, Q. Z.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, H.; Liu, Y.; Lobodenko, A.; Lokajicek, M.; Lopes de Sa, R.; Lubatti, H. J.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Madar, R.; Magaña-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martínez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Mendoza, L.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; Miconi, F.; Molina, J.; Mondal, N. K.; da Motta, H.; Mulhearn, M.; Mundim, L.; Nagy, E.; Naimuddin, M.; Narain, M.; Nayyar, R.; Neal, H. A.; Negret, J. P.; Neustroev, P.; Novaes, S. F.; Nunnemann, T.; Obrant, G.; Oguri, V.; Orduna, J.; Osman, N.; Osta, J.; Padilla, M.; Pal, A.; Parashar, N.; Parihar, V.; Park, S. K.; Partridge, R.; Parua, N.; Patwa, A.; Penning, B.; Perfilov, M.; Peters, Y.; Petridis, K.; Petrillo, G.; Pétroff, P.; Pleier, M.-A.; Podesta-Lerma, P. L. M.; Podstavkov, V. M.; Pol, M.-E.; Popov, A. V.; Prado da Silva, W. L.; Prewitt, M.; Price, D.; Prokopenko, N.; Qian, J.; Quadt, A.; Quinn, B.; Rangel, M. S.; Ranjan, K.; Ratoff, P. N.; Razumov, I.; Renkel, P.; Ripp-Baudot, I.; Rizatdinova, F.; Rominsky, M.; Ross, A.; Royon, C.; Rubinov, P.; Ruchti, R.; Sajot, G.; Salcido, P.; Sánchez-Hernández, A.; Sanders, M. P.; Sanghi, B.; Santoro, A.; Santos, A. S.; Savage, G.; Sawyer, L.; Scanlon, T.; Schamberger, R. D.; Scheglov, Y.; Schellman, H.; Schlobohm, S.; Schwanenberger, C.; Schwienhorst, R.; Sekaric, J.; Severini, H.; Shabalina, E.; Shary, V.; Shaw, S.; Shchukin, A. A.; Shivpuri, R. K.; Simak, V.; Skubic, P.; Slattery, P.; Smirnov, D.; Smith, K. J.; Snow, G. R.; Snow, J.; Snyder, S.; Söldner-Rembold, S.; Sonnenschein, L.; Soustruznik, K.; Stark, J.; Stoyanova, D. A.; Strang, M. A.; Strauss, M.; Stutte, L.; Suter, L.; Svoisky, P.; Takahashi, M.; Titov, M.; Tokmenin, V. V.; Tsai, Y.-T.; Tschann-Grimm, K.; Tsybychev, D.; Tuchming, B.; Tully, C.; Uvarov, L.; Uvarov, S.; Uzunyan, S.; Van Kooten, R.; van Leeuwen, W. M.; Varelas, N.; Varnes, E. W.; Vasilyev, I. A.; Verdier, P.; Verkheev, A. Y.; Vertogradov, L. S.; Verzocchi, M.; Vesterinen, M.; Vilanova, D.; Vokac, P.; Wahl, H. D.; Wang, M. H. L. S.; Warchol, J.; Watts, G.; Wayne, M.; Weichert, J.; Welty-Rieger, L.; White, A.; Wicke, D.; Williams, M. R. J.; Wilson, G. W.; Wobisch, M.; Wood, D. R.; Wyatt, T. R.; Xie, Y.; Yamada, R.; Yang, W.-C.; Yasuda, T.; Yatsunenko, Y. A.; Ye, W.; Ye, Z.; Yin, H.; Yip, K.; Youn, S. W.; Zennamo, J.; Zhao, T.; Zhao, T. G.; Zhou, B.; Zhu, J.; Zielinski, M.; Zieminska, D.; Zivkovic, L.

    2012-07-01

    We present a measurement of the elastic differential cross section dσ(pp¯→pp¯)/dt as a function of the four-momentum-transfer squared t. The data sample corresponds to an integrated luminosity of ≈31nb-1 collected with the D0 detector using dedicated Tevatron pp¯ Collider operating conditions at s=1.96TeV and covers the range 0.26<|t|<1.2GeV2. For |t|<0.6GeV2, dσ/dt is described by an exponential function of the form Ae-b|t| with a slope parameter b=16.86±0.10(stat)±0.20(syst)GeV-2. A change in slope is observed at |t|≈0.6GeV2, followed by a more gradual |t| dependence with increasing values of |t|.

  18. Acquired disorders of elastic tissue: Part II. decreased elastic tissue.

    PubMed

    Lewis, Kevan G; Bercovitch, Lionel; Dill, Sara W; Robinson-Bostom, Leslie

    2004-08-01

    Elastic fibers in the extracellular matrix are integral components of dermal connective tissue. The resilience and elasticity required for normal structure and function of the skin are attributable to the network of elastic tissue. Advances in our understanding of elastic tissue physiology provide a foundation for studying the pathogenesis of elastic tissue disorders. Many acquired disorders are nevertheless poorly understood owing to the paucity of reported cases. Several acquired disorders in which loss of dermal elastic tissue produces prominent clinical and histopathologic features have recently been described, including middermal elastolysis, papular elastorrhexis, and pseudoxanthoma-like papillary dermal elastolysis, which must be differentiated from more well-known disorders such as anetoderma, acquired cutis laxa, and acrokeratoelastoidosis. Learning objective At the conclusion of this learning activity, participants should have an understanding of the similarities and differences between acquired disorders of elastic tissue that are characterized by a loss of elastic tissue.

  19. Measurements of the Differential Cross Sections for the Elastic n-{sup 3}H and n-{sup 2}H Scattering at 14.1 MeV by Using an Inertial Confinement Fusion Facility

    SciTech Connect

    Frenje, J. A.; Li, C. K.; Seguin, F. H.; Casey, D. T.; Petrasso, R. D.; McNabb, D. P.; Navratil, P.; Quaglioni, S.; Sangster, T. C.; Glebov, V. Yu; Meyerhofer, D. D.

    2011-09-16

    For the first time the differential cross section for the elastic neutron-triton (n-{sup 3}H) and neutron-deuteron (n-{sup 2}H) scattering at 14.1 MeV has been measured by using an inertial confinement fusion facility. In these experiments, which were carried out by simultaneously measuring elastically scattered {sup 3}H and {sup 2}H ions from a deuterium-tritium gas-filled inertial confinement fusion capsule implosion, the differential cross section for the elastic n-{sup 3}H scattering was obtained with significantly higher accuracy than achieved in previous accelerator experiments. The results compare well with calculations that combine the resonating-group method with an ab initio no-core shell model, which demonstrate that recent advances in ab initio theory can provide an accurate description of light-ion reactions.

  20. Measurement of the neutrino neutral-current elastic differential cross section on mineral oil at E{sub {nu}{approx}1} GeV

    SciTech Connect

    Aguilar-Arevalo, A. A.; Cao, J.; Anderson, C. E.; Curioni, A.; Fleming, B. T.; Linden, S. K.; Soderberg, M.; Spitz, J.; Bazarko, A. O.; Laird, E. M.; Meyers, P. D.; Patterson, R. B.; Shoemaker, F. C.; Tanaka, H. A.; Brice, S. J.; Brown, B. C.; Finley, D. A.; Ford, R.; Garcia, F. G.; Kasper, P.

    2010-11-01

    We report a measurement of the flux-averaged neutral-current elastic differential cross section for neutrinos scattering on mineral oil (CH{sub 2}) as a function of four-momentum transferred squared, Q{sup 2}. It is obtained by measuring the kinematics of recoiling nucleons with kinetic energy greater than 50 MeV which are readily detected in MiniBooNE. This differential cross-section distribution is fit with fixed nucleon form factors apart from an axial mass M{sub A} that provides a best fit for M{sub A}=1.39{+-}0.11 GeV. Using the data from the charged-current neutrino interaction sample, a ratio of neutral-current to charged-current quasielastic cross sections as a function of Q{sup 2} has been measured. Additionally, single protons with kinetic energies above 350 MeV can be distinguished from neutrons and multiple nucleon events. Using this marker, the strange quark contribution to the neutral-current axial vector form factor at Q{sup 2}=0, {Delta}s, is found to be {Delta}s=0.08{+-}0.26.

  1. DXL: A Sounding Rocket Mission for the Study of Solar Wind Charge Exchange and Local Hot Bubble X-Ray Emission

    NASA Technical Reports Server (NTRS)

    Galeazzi, M.; Prasai, K.; Uprety, Y.; Chiao, M.; Collier, M. R.; Koutroumpa, D.; Porter, F. S.; Snowden, S.; Cravens, T.; Robertson, I.; Kuntz, K. D.; Lepri, S.; McCammon, D.

    2011-01-01

    The Diffuse X-rays from the Local galaxy (DXL) mission is an approved sounding rocket project with a first launch scheduled around December 2012. Its goal is to identify and separate the X-ray emission generated by solar wind charge exchange from that of the local hot bubble to improve our understanding of both. With 1,000 square centimeters proportional counters and grasp of about 10 square centimeters sr both in the 1/4 and 3/4 keV bands, DXL will achieve in a 5-minute flight what cannot be achieved by current and future X-ray satellites.

  2. Charge exchange in cometary coma: Discovery of H− ions in the solar wind close to comet 67P/Churyumov‐Gerasimenko

    PubMed Central

    Cravens, T. E.; Llera, K.; Goldstein, R.; Mokashi, P.; Tzou, C.‐Y.; Broiles, T.

    2015-01-01

    Abstract As Rosetta was orbiting comet 67P/Churyumov‐Gerasimenko, the Ion and Electron Sensor detected negative particles with angular distributions like those of the concurrently measured solar wind protons but with fluxes of only about 10% of the proton fluxes and energies of about 90% of the proton energies. Using well‐known cross sections and energy‐loss data, it is determined that the fluxes and energies of the negative particles are consistent with the production of H− ions in the solar wind by double charge exchange with molecules in the coma.

  3. Solar Wind Charge Exchange X-ray emission from Mercury’s exosphere: Detectability with Bepi Colombo’s MIXS spectrometer

    NASA Astrophysics Data System (ADS)

    Koutroumpa, Dimitra; Dennerl, Konrad; Leblanc, François; Modolo, Ronan

    2015-11-01

    We have conducted preliminary hybrid simulations to calculate the Solar Wind Charge Exchange (SWCX) X-ray emission in Mercury’s exosphere. Our results imply that the OVII triplet emission intensity for standard slow solar wind conditions is of the same order as the one predicted by simulations for Mars and measured by Chandra in past observations of Mars. Using an oversimplified detector and observation geometry we explore the detectability of Mercury's SWCX emission by the MIXS spectrometer on board Bepi Colombo’s planetary orbiter (MPO).

  4. Measuring one-dimensional and two-dimensional impurity density profiles on TEXTOR using combined charge exchange-beam emission spectroscopy and ultrasoft x-ray tomography

    NASA Astrophysics Data System (ADS)

    De Bock, M.; Jakubowska, K.; Hellermann, M. von; Jaspers, R.; Donné, A. J. H.; Shmaenok, L.

    2004-10-01

    Two techniques are presented that allow us to measure impurity density profiles in the TEXTOR tokamak plasma. The one-dimensional profiles are gathered by charge exchange recombination spectroscopy (CXRS) in combination with beam emission spectroscopy (BES). Combining CXRS and BES eliminate the need for absolute calibration. For two-dimensional profiles an ultrasoft x-ray tomography system has been developed. The system is spectrally resolved and produces local emissivity profiles of several ionization stages of impurities. Both systems are presently being commissioned. They are complementary and give an insight into the impurity distribution and transport in plasmas.

  5. Measurement of Anomalously Strong Emission from the 1s-9p Transition in the Spectrum of H-like Phosphorus Following Charge Exchange with Molecular Hydrogen

    NASA Technical Reports Server (NTRS)

    Leutenegger, M. A.; Beiersdorfer, P.; Brown, G. V.; Kelley, R. L.; Porter, F. S.

    2010-01-01

    We have measured K-shell x-ray spectra of highly ionized argon and phosphorus following charge exchange with molecular hydrogen at low collision energy in an electron beam ion trap using an x-ray calorimeter array with approx.6 eV resolution. We find that the emission at the high-end of the Lyman series is greater by a factor of two for phosphorus than for argon, even though the measurement was performed concurrently and the atomic numbers are similar. This does not agree with current theoretical models and deviates from the trend observed in previous measurements.

  6. Charge exchange in cometary coma: Discovery of H− ions in the solar wind close to comet 67P/Churyumov‐Gerasimenko

    PubMed Central

    Cravens, T. E.; Llera, K.; Goldstein, R.; Mokashi, P.; Tzou, C.‐Y.; Broiles, T.

    2015-01-01

    Abstract As Rosetta was orbiting comet 67P/Churyumov‐Gerasimenko, the Ion and Electron Sensor detected negative particles with angular distributions like those of the concurrently measured solar wind protons but with fluxes of only about 10% of the proton fluxes and energies of about 90% of the proton energies. Using well‐known cross sections and energy‐loss data, it is determined that the fluxes and energies of the negative particles are consistent with the production of H− ions in the solar wind by double charge exchange with molecules in the coma. PMID:27656008

  7. Dynamics of H/sup +/ + Kr and H/sup +/ + Xe elastic and charge-transfer collisions: State-selected differential cross sections at low collision energies

    SciTech Connect

    Baer, M.; Dueren, R.; Friedrich, B.; Niedner, G.; Noll, M.; Toennies, J.P.

    1987-08-01

    Elastic and charge-transfer scattering of protons by Kr and Xe targets has been investigated in a crossed-beam experiment at collision energies E/sub c.m./ = 30.6 and 51.7 eV. The charge-transfer collisions led to the formation of Kr/sup +/( /sup 2/P/sub 3/2/, /sup 2/P/sub 1/2/)+H(n = 1) and Xe/sup +/( /sup 2/P/sub 3/2/, /sup 2/P/sub 1/2/)+H(n = 1,n = 2) products respectively. Interference patterns in the state-selected relative differential cross sections were clearly resolved and have been ascribed to primary and secondary rainbows and/or Stueckelberg-type oscillations. The H/sup +/+Xe collisions have also been investigated theoretically by the exact close-coupling method. A good agreement between theory and experiment has been found. A novel method for determining the absolute H-atom detection efficiency is suggested.

  8. Elastic differential cross sections for C₄F₆ isomers in the 1.5-200 eV energy electron impact: similarities with six fluorine containing molecules and evidence of F-atom like scattering.

    PubMed

    Hoshino, M; Limão-Vieira, P; Anzai, K; Kato, H; Cho, H; Mogi, D; Tanioka, T; Ferreira da Silva, F; Almeida, D; Blanco, F; García, G; Ingólfsson, O; Tanaka, H

    2014-09-28

    We report absolute elastic differential cross sections for electron interactions with the C4F6 isomers, hexafluoro-1,3-butadiene (1,3-C4F6), hexafluoro-2-butyne (2-C4F6), and hexafluorocyclobutene (c-C4F6). The incident electron energy range is 1.5-200 eV, and the scattered electron angular range for the differential measurements varies from 15° to 150°. In all cases the absolute scale of the differential cross section was set using the relative flow technique, with helium as the reference species. Atomic-like behaviour in these scattering systems is shown here for the first time, and is further investigated by comparing the elastic cross sections for the C4F6 isomers with other fluorinated molecules, such as SF6 and CnF6 (n = 2, 3, and 6). We note that for all the six-F containing molecules, the scattering process for electron energies above 30 eV is indistinguishable. Finally, we report results for calculations of elastic differential cross sections for electron scattering from each of these isomers, within an optical potential method and assuming a screened corrected independent atom representation. The level of agreement between these calculations and our measurements is found to be quite remarkable in all cases.

  9. Local pellet based and line-integrated nonperturbing charge exchange measurements with a compact neutral particle analyzer on Large Helical Device

    SciTech Connect

    Goncharov, P. R.; Ozaki, T.; Sudo, S.; Tamura, N.; Veshchev, E. A.; Sergeev, V. Yu.; Krasilnikov, A. V.

    2006-10-15

    Experiments on suprathermal ion physics are carried out on the Large Helical Device (LHD) with a 40 channel compact neutral particle analyzer (CNPA). The analyzer is used both in passive nonperturbing chord-integral neutral particle flux measurements and for local probing with an impurity pellet. The analyzer observes trapped particles with vertical bar v{sub parallel}/v vertical bar <0.25 and the pitch angle cosine value v{sub parallel}/v changes sign along the diagnostic sight line. The measurable energy range for H{sup 0} is 1-170 keV. Radially resolved data on local H{sup 0} atomic energy spectra have been obtained on LHD by the pellet charge exchange method with CNPA, as well as chord-integral atomic energy distribution data for electron cyclotron heated, neutral beam injected, and high power ion cyclotron heated plasma. The article addresses the diagnostic technical background and the analysis scheme of measurement results taking into account the helical geometry and the species and densities of the charge exchange targets.

  10. Radiochemical study of the medium energy pion double charge exchange reactions: /sup 209/Bi(pi/sup +/pi/sup -/)/sup 209-x/At

    SciTech Connect

    Clark, J.L.

    1980-01-01

    Carrier-free radiochemical techniques have been used to measure cross sections for the double charge exchange reactions of the type /sup 209/Bi(pi/sup +/, pi/sup -/xn)/sup 209-x/At for 100, 180, and 300 MeV incident pions. The observed formation of astatine products with mass numbers ranging from 208 to 205 is interpreted as evidence of processes in which energy deposited in the initial double charge exchange interaction is subsequently dissipated through neutron evaporation. The excitation functions for these reactions are seen to rise rapidly with decreasing incident pion energy with the maximum results for this study at 100 MeV. The astatine production cross secions measured for these positive pion irradiations of thick bismuth targets must be corrected for secondary processes, particularly the pion induced production of fast alpha particles which can contribute to the total cross sections through reactions like /sup 209/Bi(alpha,xn)/sup 213-x/At. The importance of these secondary contributions was studied through a series of negative pion irradiations of bismuth in which secondary pathways furnish the only means of producing astatine. The failure of evaporation calculations to reproduce the astatine product mass yields observed in these secondary studies suggests that direct mechanisms for energetic complex particle formation are quite important. Values for the alpha decay branches of /sup 207/At, /sup 208/At, and /sup 209/At were determined through a study of the electron capture and alpha decay characteristics of chemically purified astatine fractions.

  11. Charge-exchange measurements of MHD activity during neutral beam injection in the Princeton Large Torus and the Poloidal Divertor Experiment

    SciTech Connect

    Goldston, R.J.; Kaita, R.; Beiersdorfer, P.; Gammel, G.; Herndon, D.L.; McCune, D.C.; Meyerhofer, D.D.

    1986-07-01

    The horizontally scanning, multiangle charge-exchange analyzers on the Princeton Large Torus (PLT) and the Poloidal Divertor Experiment (PDX) were used to study the effects of MHD activity on the background ion distribution function and on the beam ion slowing-down process during high-power neutral injection. Sawtooth oscillations were observed in the fast ion flux on PLT and PDX, and measurements with neutral beams providing local neutral density enhancement indicate that ions are transported radially when these events occur. With near-perpendicular injection in PDX, at the lower toroidal fields necessary to maximize beta, rapid, repetitive bursts of greatly enhanced charge-exchange flux were observed. These are associated with the ''fishbone'' MHD instability, and a substantial depletion of the perpendicular slowing-down spectrum below the injection energy was seen. A simple phenomenological model for this loss mechanism was developed, and its use in simulation codes has been successful in providing good agreement with the data. The behavior and characteristics of this model are well matched by the direct theoretical calculations.

  12. Classical description of H(1 s ) and H*(n =2 ) for cross-section calculations relevant to charge-exchange diagnostics

    NASA Astrophysics Data System (ADS)

    Cariatore, N. D.; Otranto, S.; Olson, R. E.

    2015-04-01

    In this work, we introduce a classical trajectory Monte Carlo (CTMC) methodology, specially conceived to provide a more accurate representation of charge-exchange processes between highly charged ions and H (1 s ) and H*(n=2 ) . These processes are of particular relevance in power fusion reactor programs, for which charge-exchange spectroscopy has become a useful plasma diagnostics tool. To test the methodology, electron-capture reactions from these targets by 6C ,7+N, and 8+O are studied at impact energies in the 10 -150 keV/amu range. State-selective cross sections are contrasted with those predicted by the standard microcanonical formulation of the CTMC method, the CTMC method with an energy variation of initial binding energies that produces an improved radial electron density, and the atomic orbital close-coupling method. The present results are found in to be much better agreement with the quantum-mechanical results than the results of former formulations of the CTMC method.

  13. The origin of the local 1/4-keV X-ray flux in both charge exchange and a hot bubble.

    PubMed

    Galeazzi, M; Chiao, M; Collier, M R; Cravens, T; Koutroumpa, D; Kuntz, K D; Lallement, R; Lepri, S T; McCammon, D; Morgan, K; Porter, F S; Robertson, I P; Snowden, S L; Thomas, N E; Uprety, Y; Ursino, E; Walsh, B M

    2014-08-14

    The solar neighbourhood is the closest and most easily studied sample of the Galactic interstellar medium, an understanding of which is essential for models of star formation and galaxy evolution. Observations of an unexpectedly intense diffuse flux of easily absorbed 1/4-kiloelectronvolt X-rays, coupled with the discovery that interstellar space within about a hundred parsecs of the Sun is almost completely devoid of cool absorbing gas, led to a picture of a 'local cavity' filled with X-ray-emitting hot gas, dubbed the local hot bubble. This model was recently challenged by suggestions that the emission could instead be readily produced within the Solar System by heavy solar-wind ions exchanging electrons with neutral H and He in interplanetary space, potentially removing the major piece of evidence for the local existence of million-degree gas within the Galactic disk. Here we report observations showing that the total solar-wind charge-exchange contribution is approximately 40 per cent of the 1/4-keV flux in the Galactic plane. The fact that the measured flux is not dominated by charge exchange supports the notion of a million-degree hot bubble extending about a hundred parsecs from the Sun. PMID:25079321

  14. Dynamic Elastic Tides

    NASA Astrophysics Data System (ADS)

    Wisdom, Jack; Meyer, Jennifer

    2016-04-01

    This is an exploration of dynamic tides on elastic bodies. The body is thought of as a dynamical system described by its modes of oscillation. The dynamics of these modes are governed by differential equations that depend on the rheology. The modes are damped by dissipation. Tidal friction occurs as exterior bodies excite the modes and the modes act back on the tide raising body. The whole process is governed by a closed set of differential equations. Standard results from tidal theory are recovered in a two-timescale approximation to the solution of these differential equations.

  15. Dynamic Elastic Tides

    NASA Astrophysics Data System (ADS)

    Wisdom, Jack; Meyer, Jennifer

    2016-11-01

    This is an exploration of dynamic tides on elastic bodies. The body is thought of as a dynamical system described by its modes of oscillation. The dynamics of these modes are governed by differential equations that depend on the rheology. The modes are damped by dissipation. Tidal friction occurs as exterior bodies excite the modes and the modes act back on the tide raising body. The whole process is governed by a closed set of differential equations. Standard results from tidal theory are recovered in a two-timescale approximation to the solution of these differential equations.

  16. NUMEN Project @ LNS : Heavy Ions Double Charge Exchange as a tool towards the 0νββ Nuclear Matrix Element

    NASA Astrophysics Data System (ADS)

    Agodi, C.; Cappuzzello, F.; Bonanno, D. L.; Bongiovanni, D. G.; Branchina, V.; Calabrese, S.; Calabretta, L.; Calanna, A.; Carbone, D.; Cavallaro, M.; Colonna, M.; Foti, A.; Finocchiaro, P.; Greco, V.; Lanzalone, G.; Lo Presti, D.; Longhitano, F.; Muoio, A.; Pandola, L.; Rifuggiato, D.; Tudisco, S.

    2016-06-01

    The NUMEN Project, proposed at INFN Laboratori Nazionali del Sud (LNS) in Catania, has the aim to access the nuclear matrix elements, entering the expression of the life time of double beta decay, by relevant cross sections of double charge exchange reactions. The basic point, on which it is based this innovative technique, is the coincidence of the initial and final state wave-functions in the two classes of processes and the similarity of the transition operators. A key aspect of the Project is the use of MAGNEX large acceptance magnetic spectrometer, for the detection of the ejectiles, and of the INFN LNS K800 Superconducting Cyclotron (CS), for the acceleration of the required high resolution and low emittance heavy-ion beams.

  17. Expressions for Form Factors for Inelastic Scattering and Charge Exchange in Plane-Wave, Distorted-Wave, and Coupled-Channels Reaction Formalisms

    SciTech Connect

    Dietrich, F S

    2006-09-25

    This document is intended to facilitate calculation of inelastic scattering and charge-exchange cross sections in a variety of reaction models, including the plane-wave and distorted-wave approximations and the full coupled-channels treatments. Expressions are given for the coupling potentials between the relevant channels in both coordinate and momentum space. In particular, it is expected that the plane-wave calculations should be useful as a check on the correctness of coupled-channels calculations. The Fourier transform methods used to calculate the plane-wave approximation cross sections are also intended to be used to generate the transition potentials for coupled-channels codes, using a folding model with local effective interactions. Specific expressions are given for calculating transition densities for the folding model in the random phase approximation (RPA).

  18. A comparison of empirical and experimental O7+, O8+, and O/H values, with applications to terrestrial solar wind charge exchange

    NASA Astrophysics Data System (ADS)

    Whittaker, Ian C.; Sembay, Steve

    2016-07-01

    Solar wind charge exchange occurs at Earth between the neutral planetary exosphere and highly charged ions of the solar wind. The main challenge in predicting the resultant photon flux in the X-ray energy bands is due to the interaction efficiency, known as the α value. This study produces experimental α values at the Earth, for oxygen emission in the range of 0.5-0.7 keV. Thirteen years of data from the Advanced Composition Explorer are examined, comparing O7+ and O8+ abundances, as well as O/H to other solar wind parameters allowing all parameters in the αO7,8+ calculation to be estimated based on solar wind velocity. Finally, a table is produced for a range of solar wind speeds giving average O7+ and O8+ abundances, O/H, and αO7,8+ values.

  19. Measurement of deuterium density profiles in the H-mode steep gradient region using charge exchange recombination spectroscopy on DIII-D

    NASA Astrophysics Data System (ADS)

    Haskey, S. R.; Grierson, B. A.; Burrell, K. H.; Chrystal, C.; Groebner, R. J.; Kaplan, D. H.; Pablant, N. A.; Stagner, L.

    2016-11-01

    Recent completion of a thirty two channel main-ion (deuterium) charge exchange recombination spectroscopy (CER) diagnostic on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] enables detailed comparisons between impurity and main-ion temperature, density, and toroidal rotation. In a H-mode DIII-D discharge, these new measurement capabilities are used to provide the deuterium density profile, demonstrate the importance of profile alignment between Thomson scattering and CER diagnostics, and aid in determining the electron temperature at the separatrix. Sixteen sightlines cover the core of the plasma and another sixteen are densely packed towards the plasma edge, providing high resolution measurements across the pedestal and steep gradient region in H-mode plasmas. Extracting useful physical quantities such as deuterium density is challenging due to multiple photoemission processes. These challenges are overcome using a detailed fitting model and by forward modeling the photoemission using the FIDASIM code, which implements a comprehensive collisional radiative model.

  20. Visible and near UV photon spectroscopy of charge-exchange collisions between Ar7+ and Li at 105 keV

    NASA Astrophysics Data System (ADS)

    Jacquet, E.; Boduch, P.; Chantepie, M.; Druetta, M.; Hennecart, D.; Husson, X.; Lecler, D.; Wilson, M.

    1994-04-01

    Charge exchange collisions at 105 keV between Ar7+ ions and lithium atoms have been studied by photon spectroscopy in the 2000-6000 Å wavelength range. A large number of new lines in Ar VII have been identified with the help of ab initio pseudo-relativistic Hartree-Fock calculations taking into account electrostatic interactions between 3snl (n = 6-10), 3 pnl (n = 4-6) and 3dnl (n = 4) configurations. They correspond to transitions 3snl-3sn'l' with n = 7, 8, 9 and Δn = 1 and 2. Lines in Ar VI were also observed and identified as transitions 3s2nl-3s2n'l' and 3s3pnl-3s3pn'l'(n = 6, 7) and Δn = 1.

  1. Profile Measurement of Ion Temperature and Toroidal Rotation Velocity with Charge Exchange Recombination Spectroscopy Diagnostics in the HL-2A Tokamak

    NASA Astrophysics Data System (ADS)

    Wu, Jing; Yao, Lieming; Zhu, Jianhua; Han, Xiaoyu; Li, Wenzhu

    2012-11-01

    This paper deals with the profile measurement of impurity ion temperature and toroidal rotation velocity that can be achieved by using the charge exchange recombination spectrum (CXRS) diagnostics tool built on the HL-2A tokamak. By using CXRS, an accurate impurity ion temperature and toroidal plasma rotation velocity profile can be achieved under the condition of neutral beam injection (NBI) heating. Considering the edge effect of the line of CVI 529.06 nm (n = 8~7), which contains three lines (active exciting spectral line (ACX), passivity exciting spectral line (PCX) and electron exciting spectral line (ICE)), and using three Gaussian fitted curves, we obtain the following experimental results: the core ion temperature of HL-2A device is nearly thousands of eV, and the plasma rotation velocity reaches about 104 m · s-1. At the end of paper, some explanations are presented for the relationship between the curves and the inner physical mechanism.

  2. Determination of {sup 16}O and {sup 18}O sensitivity factors and charge-exchange processes in low-energy ion scattering

    SciTech Connect

    Tellez, H.; Chater, R. J.; Fearn, S.; Symianakis, E.; Kilner, J. A.; Brongersma, H. H.

    2012-10-08

    Quantitative analysis in low-energy ion scattering (LEIS) requires an understanding of the charge-exchange processes to estimate the elemental sensitivity factors. In this work, the neutralization of He{sup +} scattered by {sup 18}O-exchanged silica at energies between 0.6 and 7 keV was studied. The process is dominated by Auger neutralization for E{sub i} < 0.8 keV. An additional mechanism starts above the reionization threshold. This collision-induced neutralization becomes the dominant mechanism for E{sub i} > 2 keV. The ion fractions P{sup +} were determined for Si and O using the characteristic velocity method to quantify the surface density. The {sup 18}O/{sup 16}O sensitivity ratio indicates an 18% higher sensitivity for the heavier O isotope.

  3. Positive-pion double-charge-exchange reaction: experiments on the isotopic pairs oxygen-16,18 and magnesium-24,26

    SciTech Connect

    Greene, S.J.

    1981-06-01

    The (..pi../sup +/,..pi../sup -/) double-charge-exchange (DCX) reaction has been performed on targets of T = 0,1 isospin (and isotopic) pairs /sup 16/ /sup 18/O and /sup 24/ /sup 26/Mg. Energy excitation functions of d sigma/d ..cap omega.., across the (3,3) ..pi..-N resonance, are presented for transitions to double-isobaric analog state (DIAS) and non-DIAS ground-state residual nuclei. Angular distributions in the region of 5/sup 0/ to 33/sup 0/ are presented for the DIAS from the T = 1 nuclei. The similarities and differences of DIAS and non-DIAS distributions are discussed in relation to reaction-mechanism and nuclear-structure effects. Also, a simple, two-amplitude model for the /sup 18/O excitation function, consistent with the data, is presented. The utility of DCX in nuclear mass measurements is discussed, with some examples.

  4. Interaction of plasma jets produced from pinch plasma with neutral atoms in order to achieve an effective charge exchange table top X-laser

    SciTech Connect

    Engel, A.; Lebert, R.; Koshelev, K. N.; Sidelnikov, Yu. V.; Churilov, S. S.; Gavrilescu, C.; Neff, W.

    1997-05-05

    Charge exchange recombination is known as an effective scheme to get population inversion in the EUV-range. Highly ionised plasma jets and a neutral target could be very efficient ({sigma}{sub CE}>10{sup -15} cm{sup 2}) to realisation of this atomic scheme. Theoretical estimates and preliminary experiments show that for plasma focus with a stored energy of several kJ one can reach a substantial population inversion for ions of light elements with charge number Z<10. Experimental studies of production of these plasma jets in a 2 kJ plasma focus device is presented. Moreover the optimal properties of possible targets are investigated. Experimental results for the interaction of the plasma jets and targets are presented.

  5. Production of a high brightness H{sup -} beam by charge exchange of a hydrogen atom beam in a sodium jet

    SciTech Connect

    Davydenko, V.; Ivanov, A.; Kolmogorov, A.; Zelenski, A.

    2011-09-26

    Production of H{sup -} beams for applications in accelerators via charge exchange of a high brightness hydrogen neutral beam in a sodium jet cell is experimentally studied in a joint experiment by the Brookhaven National Laboratory (BNL) and the Budker Institute of Nuclear Physcis (BINP). In the experiment, a hydrogen atomic beam with an energy 3-6 keV, an equivalent current up to 5 A and a pulse duration 200 microseconds is used. Initial results demonstrate that an H{sup -} beam with a current 36 mA, an energy 5 keV and {approx}0.15 cm{center_dot}mrad normalized emittance was obtained. The recirculating sodium jet target with an entrance aperture 2 cm, which was developed for the BNL optically pumped polarized ion source, is used in the experiment. To increase the H{sup -} beam current, geometric focusing of the hydrogen neutral beam will be used in the future experiments. In addition, the effects of H{sup -} beam space-charge and sodium-jet stability will be studied to determine the basic limitations of this approach. The atomic beam is produced by charge exchange of a proton beam in a pulsed hydrogen target. The proton beam is formed by an ion source with a four-electrode multiaperture ion-optical system with small-size apertures. The plasma emission surface is formed by the plasma expansion from an arc plasma generator. The transverse ion temperature at the emission surface is 0.2 eV.

  6. Elastic scattering of hadrons

    NASA Astrophysics Data System (ADS)

    Dremin, I. M.

    2013-01-01

    Colliding high-energy hadrons either produce new particles or scatter elastically with their quantum numbers conserved and no other particles produced. We consider the latter case here. Although inelastic processes dominate at high energies, elastic scattering contributes considerably (18-25%) to the total cross section. Its share first decreases and then increases at higher energies. Small-angle scattering prevails at all energies. Some characteristic features can be seen that provide information on the geometrical structure of the colliding particles and the relevant dynamical mechanisms. The steep Gaussian peak at small angles is followed by the exponential (Orear) regime with some shoulders and dips, and then by a power-law decrease. Results from various theoretical approaches are compared with experimental data. Phenomenological models claiming to describe this process are reviewed. The unitarity condition predicts an exponential fall for the differential cross section with an additional substructure to occur exactly between the low momentum transfer diffraction cone and a power-law, hard parton scattering regime under high momentum transfer. Data on the interference of the Coulomb and nuclear parts of amplitudes at extremely small angles provide the value of the real part of the forward scattering amplitude. The real part of the elastic scattering amplitude and the contribution of inelastic processes to the imaginary part of this amplitude (the so-called overlap function) are also discussed. Problems related to the scaling behavior of the differential cross section are considered. The power-law regime at highest momentum transfer is briefly described.

  7. Charge exchange in 3-30 keV H+ scattering off clean and AlF3 -covered Al(111) surfaces II. Theoretical study

    NASA Astrophysics Data System (ADS)

    Lugo, J. O.; Goldberg, E. C.; Sánchez, E. A.; Grizzi, O.

    2005-07-01

    The collision process of H+ with clean and AlF3 covered Al(111) surfaces is theoretically studied for large scattering angles and different ion incoming energies. The energy distributions of the charge fractions are analyzed as a function of the backscattered particle energy. Important differences between the two surfaces are found: in the case of pure Al the outgoing hydrogen particles are predominantly neutral, with a 10% of negative ions, while in the case of AlF3 an important positive charge fraction is observed. The theoretical calculation reproduces the experimental trends, and shows that these results are strongly related with the electronic structures in each case. In both surfaces a resonant mechanism is responsible for the charge exchange, but while in the pure Al case only the valence band states are involved, in the AlF3 case the promotion of the projectile energy level by the interaction with the core surface states inhibits the electron capture from the valence band.

  8. Measurement of radial profiles of density ratio of helium to hydrogen ion using charge exchange spectroscopy with two-wavelength spectrometer.

    PubMed

    Ida, K; Yoshinuma, M; Wieland, B; Goto, M; Nakamura, Y; Kobayashi, M; Murakami, I; Moon, C

    2015-12-01

    Radial profiles of density ratio of helium to hydrogen ions are measured using the charge exchange spectroscopy technique with the two-wavelength spectrometer system in the large helical device. The two-wavelength spectrometer system consists of a dichroic mirror box, a spectrometer with two grating and two camera lenses, and one CCD detector. The dichroic mirror box is used to divide the light of one fiber from the plasma to two fibers, one for HeII (λ = 468.6 nm) and the other for H(α) (λ = 656.3 nm), that are connected to the entrance slit of the spectrometer to eliminate the interference between the HeII and the H(α) spectra on the CCD. This system provides a simultaneous measurement of helium and hydrogen ion density ratio at 8 exact same locations (8 spatial channels) with a time resolution of >40 ms in the wide range of the density ratio of 0.05-5.

  9. A diagnostic neutral beam system for the MST reversed-field pinch: Charge-exchange recombination spectroscopy and Rutherford scattering (abstract)

    NASA Astrophysics Data System (ADS)

    Den Hartog, D. J.; Fiksel, G.; Davydenko, V.; Ivanov, A.; Mishagin, V.

    1999-01-01

    A diagnostic neutral beam system is being purchased for the MST reversed-field pinch. Initially, this beam will be used for charge-exchange recombination spectroscopy (CHERS) to measure impurity ion velocity and temperature, both equilibrium and fluctuating. This work is an extension of an existing MST spectroscopic diagnostic which has successfully measured chord-averaged flow with 10 μs time resolution [D. J. Den Hartog and R. J. Fonck, Rev. Sci. Instrum. 65, 3238 (1994)]. CHERS will provide high spatial resolution, critically needed for the investigation of fluctuations associated with the dynamo and transport. This beam will also be applied to Rutherford scattering for local measurements of majority ion velocity and temperature. Ion velocity is determined by the shift of the energy spectrum of the scattered neutral beam; ion temperature by the width of the energy spectrum. The scattered spectrum will be detected by two multichannel neutral particle analyzers. In order to achieve a time resolution of about 10 μs, the neutral beam equivalent current density and current must be high; both of these characteristics are hallmarks of the DINA beam design.

  10. Charge exchange in Be4+-H(n = 1, 2) collisions studied systematically by atomic-orbital close-coupling calculations

    NASA Astrophysics Data System (ADS)

    Igenbergs, K.; Schweinzer, J.; Aumayr, F.

    2009-12-01

    Charge exchange in Be4+-H(n = 1, 2) collisions was studied using the atomic-orbital close-coupling formalism in its impact parameter description and applying electron translational factors. Calculations were carried out in the energy range of 1-750 keV amu-1 with fully stripped beryllium ions impacting on atomic hydrogen in its ground state (1s) and in the excited n = 2 states. An optimized description of both collision centres was determined by analysing the convergence of the total cross sections and also by comparison with other theoretical approaches. This optimized description consists of up to 170 basis states involving hydrogen-like states and pseudostates. We present total, n-resolved as well as nell-resolved cross sections. The latter are needed to evaluate the emission cross sections in two limiting collisional plasma environments, i.e. single-collisional and multi-collisional. The calculated emission cross sections are compared with experimental data from the fusion experiment JET. Taking the experimental environment and certain characteristics of the theoretical methods into account, the agreement can be considered to be quite good.

  11. On Lunar Exospheric Column Densities and Solar Wind Access Beyond the Terminator from ROSAT Soft X-Ray Observations of Solar Wind Charge Exchange

    NASA Technical Reports Server (NTRS)

    Collier, Michael R.; Snowden, S. L.; Sarantos, M.; Benna, M.; Carter, J. A.; Cravens, T. E.; Farrell, W. M.; Fatemi, S.; Hills, H. Kent; Hodges, R. R.; Holmstrom, M.; Kuntz, K. D.; Porter, F. Scott; Read, A.; Robertson, I. P.; Sembay, S. F.; Sibeck, D. G.; Stubbs, T. J.; Travnicek, P.; Walsh, B. M.

    2014-01-01

    We analyze the Rontgen satellite (ROSAT) position sensitive proportional counter soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the surface brightness in three wedges: two 19 deg wedges (one north and one south) 13-32 deg off the terminator toward the dark side and one wedge 38 deg wide centered on the antisolar direction. The radial profiles of both the north and the south wedges show significant limb brightening that is absent in the 38 deg wide antisolar wedge. An analysis of the soft X-ray intensity increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere based on lunar exospheric models and hybrid simulation results of solar wind access beyond the terminator. Soft X-ray imaging thus can independently infer the total lunar limb column density including all species, a property that before now has not been measured, and provide a large-scale picture of the solar wind-lunar interaction. Because the SWCX signal appears to be dominated by exospheric species arising from solar wind implantation, this technique can also determine how the exosphere varies with solar wind conditions. Now, along with Mars, Venus, and Earth, the Moon represents another solar system body at which SWCX has been observed.

  12. Program of Measurement of the Asymmetry P at the Minima of the Differential Cross Section for Elastic {pi}{sup +}p Scattering

    SciTech Connect

    Beloglazov, Yu.A.; Kovalev, A.I.; Kruglov, S.P.; Novinsky, D.V.; Sumachev, V.V.; Trautman, V.Yu.; Filimonov, E.A.; Shchedrov, V.A.; Alekseev, I.G.; Budkovsky, P.E.; Zhurkin, V.V.; Kanavets, V.P.; Koroleva, L.I.; Morozov, B.V.; Nesterov, V.M.; Ryltsov, V.V.; Svirida, D.N.; Sulimov, A.D.; Bazhanov, N.A.; Bunyatova, E.I.

    2005-03-01

    A program of measurement of the polarization parameter P in elastic {pi}{sup +}p interaction in the resonance region of backward pion scattering is presented. This program is aimed at determining the bifurcation points of the trajectory of zeros of the pion-nucleon amplitude and, hence, at unambiguously reconstructing the amplitude of {pi}N scattering in the second resonance region. It is planned to perform a relevant experiment in a pion beam from the accelerator of the Institute of Experimental and Theoretical Physics (ITEP, Moscow)

  13. Measurement and calculation of absolute single- and double-charge-exchange cross sections for O6 + ions at 1.17 and 2.33 keV/u impacting He and H2

    NASA Astrophysics Data System (ADS)

    Machacek, J. R.; Mahapatra, D. P.; Schultz, D. R.; Ralchenko, Yu.; Chutjian, A.; Simcic, J.; Mawhorter, R. J.

    2014-11-01

    Absolute single- and double-charge-exchange cross sections for the astrophysically prominent O6 + ion with the atomic and molecular targets He and H2 are reported. These collisions give rise to x-ray emissions in the interplanetary medium, planetary atmospheres, and comets as they approach the sun. Measurements have been carried out using the Caltech Jet Propulsion Laboratory electron cyclotron resonance ion source with O6 + at energies of 1.17 and 2.33 keV/u characteristic of the slow and fast components of the solar wind. Absolute charge-exchange (CE) data are derived from knowledge of the target gas pressure, target path length, incident ion current, and charge-exchanged ion currents. These data are compared with results obtained using the n -electron classical trajectory Monte Carlo method. The radiative and Auger evolution of ion populations following one- and two-electron transfers is calculated with the time-dependent collisional-radiative code nomad using atomic data from the flexible atomic code. Calculated CE emission spectra for 100 Å <λ <1400 Å are reported as well and compared with experimental sublevel spectra and cross sections.

  14. Measurement of the Muon Neutrino Double-Differential Charged Current Quasi-Elastic Like Cross Section on a Hydrocarbon Target at Ev ~ 3.5 GeV

    SciTech Connect

    Hurtado Anampa, Kenyi Paolo

    2016-01-01

    The MINERvA Experiment (Main Injector Experiment v ₋ A interaction) [1] is a highly segmented detector of neutrinos, able to record events with high precision (over than thirteen million event in a four year run), using the NuMI Beam (Neutrino Main Injector) at the Fermi National Accelerator Laboratory [2]. This thesis presents a measurement of the Charged Current Quasi-Elastic Like1 vμ interaction on polystyrene scintillator (CH) in the MINERvA experiment with neutrino energies between 1.5 and 10 GeV. We use data taken between2 March 2010 and April 2012. The interactions were selected by requiring a negative muon, a reconstructed and identified proton, no michel electrons in the final state (in order to get rid of soft pions decaying) and a low calorimetric recoil energy away from the interaction vertex. The analysis is performed on 66,214 quasi-elastic like event candidates in the detectors tracker region with an estimated purity of 74%. The final measurement reported is a double differential cross sections in terms of the muon longitudinal and transversal momentum observables.

  15. Model-independent analysis of Airy structures in the {sup 16}O+{sup 12}C and {sup 16}O+{sup 16}O elastic scattering differential cross sections at 13-22 MeV/nucleon

    SciTech Connect

    Korda, V. Yu.; Molev, A. S.; Klepikov, V. F.; Korda, L. P.

    2009-02-15

    We present the results of the model-independent analysis of Airy structures in the {sup 16}O+{sup 12}C and {sup 16}O+{sup 16}O elastic scattering differential cross sections at 13-22 MeV/nucleon. The analysis has been performed with help of a procedure based on the application of the evolutionary algorithm, which enables us to extract the nuclear part of the scattering matrix S{sub N}(l) as a complex function of angular momentum directly from the scattering data. Contrary to the commonly used model approaches, our procedure gives the better fits and leads to the S{sub N}(l) representations defined by the moduli and the nuclear phases exhibiting smooth monotonic dependencies on l.

  16. DAEs and PDEs in elastic multibody systems

    NASA Astrophysics Data System (ADS)

    Simeon, B.

    1998-12-01

    Elastic multibody systems arise in the simulation of vehicles, robots, air- and spacecrafts. They feature a mixed structure with differential-algebraic equations (DAEs) governing the gross motion and partial differential equations (PDEs) describing the elastic deformation of particular bodies. We introduce a general modelling framework for this new application field and discuss numerical simulation techniques from several points of view. Due to different time scales, singular perturbation theory and model reduction play an important role. A slider crank mechanism with a 2D FE grid for the elastic connecting rod illustrates the techniques.

  17. XMM-Newton and Suzaku X-Ray Shadowing Measurements of the Solar Wind Charge Exchange, Local Bubble, and Galactic Halo Emission

    NASA Astrophysics Data System (ADS)

    Henley, David B.; Shelton, Robin L.

    2015-07-01

    We present results from a sample of XMM-Newton and Suzaku observations of interstellar clouds that cast shadows in the soft X-ray background (SXRB)—the first uniform analysis of such a sample from these missions. By fitting to the on- and off-shadow spectra, we separated the foreground and Galactic halo components of the SXRB. We tested different foreground models—two solar wind charge exchange (SWCX) models and a Local Bubble (LB) model. We also examined different abundance tables. We found that Anders & Grevesse abundances, commonly used in previous SXRB studies, may result in overestimated foreground brightnesses and halo temperatures. We also found that assuming a single solar wind ionization temperature for a SWCX model can lead to unreliable results. We compared our measurements of the foreground emission with predictions of the SWCX emission from a smooth solar wind, finding only partial agreement. Using available observation-specific SWCX predictions and various plausible assumptions, we placed an upper limit on the LB's O vii intensity of ∼0.8 {{photons}} {{{cm}}}-2 {{{s}}}-1 {{{sr}}}-1 (90% confidence). Comparing the halo results obtained with SWCX and LB foreground models implies that, if the foreground is dominated by SWCX and is brighter than ∼1.5× {10}-12 {{erg}} {{{cm}}}-2 {{{s}}}-1 {{{deg}}}-2 (0.4–1.0 {{keV}}), then using an LB foreground model may bias the halo temperature upward and the 0.5–2.0 {{keV}} surface brightness downward by ∼(0.2-0.3)× {10}6 {{K}} and ∼(1-2)× {10}-12 {{erg}} {{{cm}}}-2 {{{s}}}-1 {{{deg}}}-2, respectively. Similarly, comparing results from different observatories implies that there may be uncertainties in the halo temperature and surface brightness of up to ∼0.2× {10}6 {{K}} and ∼25%, respectively, in addition to the statistical uncertainties. These uncertainties or biases may limit the ability of X-ray measurements to discriminate between Galactic halo models.

  18. Charge exchange spectroscopy of multiply charged ions for the development of the EUV light source for the next generation photo lithography

    NASA Astrophysics Data System (ADS)

    Tanuma, Hajime

    2015-09-01

    As a candidate of an extreme ultra-violet (EUV) light source for a next generation lithography, laser produced plasmas (LPP) of Xe and Sn have been investigated intensively in this decade because these plasmas have a strong emission around 13.5 nm which had been determined as the wavelength for the EUV lithography. This emission was considered to be due to multiply charged Xe and Sn ions in hot plasmas. However, the detail atomic spectroscopic data of these multiply charged heavy ions had not been reported yet. To provide atomic data for the understanding and development of the LPP as the EUV light source, we have observed the EUV emission spectra from individual charge states of Xe and Sn ions by means of a charge exchange spectroscopy method. Multiply charged Xeq+ (q = 7-23) and Snq+ (q = 5-21) ions were produced with a 14.25 GHz electron cyclotron resonance ion source, and a charge-selected ion beam was directed into a collision chamber, where the ion interact with a target gas of He and Xe. EUV emissions from the collision center were observed with a compact flat-field grazing-incident spectrometer equipped with a liquid nitrogen cooled CCD camera. In experiments using Xe ions, we have found only Xe XI has a strong UTA (unresolved transition array) around 13.5 nm. On the other hand, various charge states of Sn from VIII to XIV contribute to the 13.5 nm emission. Identification of the transition lines was carried out by calculations using the Hebrew university Livermore laboratory atomic physics code and the Cowan code. Most of the emissions in the EUV region are attributed to the 4p-4d and 4d- nl (nl = 4f, 5p, and 5f) transitions. However, the 4d-4f transitions have approximately constant differences of about 0.5 nm between the experimental and theoretical results. This can be explained by considering the strong configuration interactions in the n=4 subshells. Using the experimental transition wavelengths of multiply charged Sn ions, theoretical modeling of

  19. Soft X-ray study of solar wind charge exchange from the Earth's magnetosphere : Suzaku observations and a future X-ray imaging mission concept

    NASA Astrophysics Data System (ADS)

    Ezoe, Y.; Ishisaki, Y.; Ohashi, T.; Ishikawa, K.; Miyoshi, Y.; Fujimoto, R.; Terada, N.; Kasahara, S.; Fujimoto, M.; Mitsuda, K.; Nishijo, K.; Noda, A.

    2013-12-01

    Soft X-ray observations of solar wind charge exchange (SWCX) emission from the Earth's magnetosphere using the Japanese X-ray astronomy satellite Suzaku are shown, together with our X-ray imaging mission concept to characterize the solar wind interaction with the magnetosphere. In recent years, the SWCX emission from the Earth's magnetosphere, originally discovered as unexplained noise during the soft X-ray all sky survey (Snowden et al. 1994), is receiving increased attention on studying geospace. The SWCX is a reaction between neutrals in exosphere and highly charged ions in the magnetosphere originated from solar wind. Robertson et al. (2005) modeled the SWCX emission as seen from an observation point 50 Re from Earth. In the resulting X-ray intensities, the magnetopause, bow shock and cusp were clearly visible. High sensitivity soft X-ray observation with CCDs onboard recent X-ray astronomy satellites enables us to resolve SWCX emission lines and investigate time correlation with solar wind as observed with ACE and WIND more accurately. Suzaku is the 5th Japanese X-ray astronomy satellite launched in 2005. The line of sight direction through cusp is observable, while constraints on Earth limb avoidance angle of other satellites often limits observable regions. Suzaku firstly detected the SWCX emission while pointing in the direction of the north ecliptic pole (Fujimoto et al. 2007). Using the Tsyganenko 1996 magnetic field model, the distance to the nearest SWCX region was estimated as 2-8 Re, implying that the line of sight direction can be through magnetospheric cusp. Ezoe et al. (2010) reported SWCX events toward the sub-solar side of the magnetosheath. These cusp and sub-solar side magnetosheath regions are predicted to show high SWCX fluxes by Robertson et al. (2005). On the other hand, Ishikawa et al. (2013) discovered a similarly strong SWCX event when the line of sight direction did not transverse these two regions. Motivated by these detections

  20. Momentum-transfer, differential and spin-exchange cross sections in the elastic scattering of low-energy electrons by heavy alkali-metal atoms.

    NASA Astrophysics Data System (ADS)

    Bahrim, Cristian; Thumm, Uwe; Fabrikant, Ilya I.

    2000-06-01

    Based on the relativistic Dirac R-matrix method, we analyze various angle-dependent cross sections for electron scattering by Rb, Cs and Fr targets at energies below 3 eV. We show our angle-dependent and total spin-exchange cross sections for scattering of non-polarized (or polarized) electrons by polarized (or non-polarized) Rb, Cs and Fr targets, and we compare them with available experimental data (B. Jaduszliwer, N.D. Bhaskar, and B. Bederson Phys.Rev. A 14), 162 (1976).. The influence of relativistic effects is discussed. From the energy and angular dependence analysis of the differential cross section, we obtain clear evidence of the Cs^-(^3F^o) shape resonance at 1.528 eV, in excellent agreement with accurate experiments (W. Gehenn and E. Reichert, J.Phys. B 10), 3105 (1977).. We compare our electron momentum-transfer cross section with available data obtained in swarm experiments for Rb (Y. Nakamura, Trans. IEE of Japan 102-A), 23 (1982). and Cs (H.T. Saelee and J. Lucas, J.Phys. D 12), 1275 (1979)..

  1. Measurement of the free neutron-proton analyzing power and spin transfer parameters in the charge exchange region at 790 MeV

    SciTech Connect

    Ransome, R.D.

    1981-07-01

    The free neutron-proton analyzing power and the spin transfer parameters (K/sub NN/, K/sub SS/, K/sub SL/, and K/sub LL/) were measured at the Los Alamos Meson Physics Facility at 790 MeV between 165/sup 0/ and 180/sup 0/ center of mass. A 40% polarized neutron beam incident on a liquid hydrogen target was used. The recoil protons were momentum analyzed with a magnetic spectrometer to isolate elastic scatters. A large solid angle carbon polarimeter was used to measure the proton polarization. The measurements are the first at this energy and are in basic agreement with pre-existing phase shift solutions. The proton-carbon analyzing power was measured between 500 and 750 MeV. An empirical fit to the proton-carbon analyzing power between 100 and 750 MeV was done.

  2. Scaling, elasticity, and CLPT

    NASA Technical Reports Server (NTRS)

    Brunelle, Eugene J.

    1994-01-01

    The first few viewgraphs describe the general solution properties of linear elasticity theory which are given by the following two statements: (1) for stress B.C. on S(sub sigma) and zero displacement B.C. on S(sub u) the altered displacements u(sub i)(*) and the actual stresses tau(sub ij) are elastically dependent on Poisson's ratio nu alone: thus the actual displacements are given by u(sub i) = mu(exp -1)u(sub i)(*); and (2) for zero stress B.C. on S(sub sigma) and displacement B.C. on S(sub u) the actual displacements u(sub i) and the altered stresses tau(sub ij)(*) are elastically dependent on Poisson's ratio nu alone: thus the actual stresses are given by tau(sub ij) = E tau(sub ij)(*). The remaining viewgraphs describe the minimum parameter formulation of the general classical laminate theory plate problem as follows: The general CLT plate problem is expressed as a 3 x 3 system of differential equations in the displacements u, v, and w. The eighteen (six each) A(sub ij), B(sub ij), and D(sub ij) system coefficients are ply-weighted sums of the transformed reduced stiffnesses (bar-Q(sub ij))(sub k); the (bar-Q(sub ij))(sub k) in turn depend on six reduced stiffnesses (Q(sub ij))(sub k) and the material and geometry properties of the k(sup th) layer. This paper develops a method for redefining the system coefficients, the displacement components (u,v,w), and the position components (x,y) such that a minimum parameter formulation is possible. The pivotal steps in this method are (1) the reduction of (bar-Q(sub ij))(sub k) dependencies to just two constants Q(*) = (Q(12) + 2Q(66))/(Q(11)Q(22))(exp 1/2) and F(*) - (Q(22)/Q(11))(exp 1/2) in terms of ply-independent reference values Q(sub ij); (2) the reduction of the remaining portions of the A, B, and D coefficients to nondimensional ply-weighted sums (with 0 to 1 ranges) that are independent of Q(*) and F(*); and (3) the introduction of simple coordinate stretchings for u, v, w and x,y such that the process is

  3. Relationship between the Uncompensated Price Elasticity and the Income Elasticity of Demand under Conditions of Additive Preferences.

    PubMed

    Sabatelli, Lorenzo

    2016-01-01

    Income and price elasticity of demand quantify the responsiveness of markets to changes in income and in prices, respectively. Under the assumptions of utility maximization and preference independence (additive preferences), mathematical relationships between income elasticity values and the uncompensated own and cross price elasticity of demand are here derived using the differential approach to demand analysis. Key parameters are: the elasticity of the marginal utility of income, and the average budget share. The proposed method can be used to forecast the direct and indirect impact of price changes and of financial instruments of policy using available estimates of the income elasticity of demand. PMID:26999511

  4. Relationship between the Uncompensated Price Elasticity and the Income Elasticity of Demand under Conditions of Additive Preferences

    PubMed Central

    Sabatelli, Lorenzo

    2016-01-01

    Income and price elasticity of demand quantify the responsiveness of markets to changes in income and in prices, respectively. Under the assumptions of utility maximization and preference independence (additive preferences), mathematical relationships between income elasticity values and the uncompensated own and cross price elasticity of demand are here derived using the differential approach to demand analysis. Key parameters are: the elasticity of the marginal utility of income, and the average budget share. The proposed method can be used to forecast the direct and indirect impact of price changes and of financial instruments of policy using available estimates of the income elasticity of demand. PMID:26999511

  5. Linear Lumbar Localized Lysis of Elastic Fibers

    PubMed Central

    Tschen, Jaime A.

    2013-01-01

    Background: The absence or loss of elastic fibers in the skin is referred to as dermal elastolysis. Purpose: This paper describes a woman with a distinctive clinical presentation of mid-dermal elastolysis characterized morphologically by multiple horizontal raised bands on the lower back. Methods: A 20-year-old Filipino woman presented with multiple asymptomatic, flesh-colored, raised, firm, linear, cord-like bands on the lumbar area of her back. There were neither similar lesions elsewhere nor a family member with this condition. Results: Microscopic examination of the raised band showed nearly complete absence of elastic fibers in the mid dermis. In contrast, a biopsy of symmetrically located normal-appearing skin showed a uniform distribution of elastic fibers throughout the dermis. Linear lumbar localized elastolysis is a descriptive designation that accurately reflects a correlation of the clinical and pathological changes of this condition. Conclusion: The clinical differential of raised horizontal cord-like bands on the lower back (without a family history of an inherited elastic fiber disorder, a prior history of trauma, or a significant change in weight or exercise habit) includes linear focal elastosis and linear lumbar localized elastolysis. Microscopic evaluation of a Verhoeff-van Gieson stained lesion specimen (which may be accompanied by a biopsy of normal-appearing skin for comparison) will readily differentiate these conditions. The former is usually characterized by increased elastic fibers, whereas the latter, as in this patient, shows a paucity or absence of elastic fibers in the mid dermis. PMID:23882313

  6. Electron Elastic-Scattering Cross-Section Database

    National Institute of Standards and Technology Data Gateway

    SRD 64 NIST Electron Elastic-Scattering Cross-Section Database (PC database, no charge)   This database provides values of differential elastic-scattering cross sections, corresponding total elastic-scattering cross sections, phase shifts, and transport cross sections for elements with atomic numbers from 1 to 96 and for electron energies between 50 eV and 20,000 eV (in steps of 1 eV).

  7. Elastically Decoupling Dark Matter.

    PubMed

    Kuflik, Eric; Perelstein, Maxim; Lorier, Nicolas Rey-Le; Tsai, Yu-Dai

    2016-06-01

    We present a novel dark matter candidate, an elastically decoupling relic, which is a cold thermal relic whose present abundance is determined by the cross section of its elastic scattering on standard model particles. The dark matter candidate is predicted to have a mass ranging from a few to a few hundred MeV, and an elastic scattering cross section with electrons, photons and/or neutrinos in the 10^{-3}-1  fb range. PMID:27314712

  8. Elastically Decoupling Dark Matter.

    PubMed

    Kuflik, Eric; Perelstein, Maxim; Lorier, Nicolas Rey-Le; Tsai, Yu-Dai

    2016-06-01

    We present a novel dark matter candidate, an elastically decoupling relic, which is a cold thermal relic whose present abundance is determined by the cross section of its elastic scattering on standard model particles. The dark matter candidate is predicted to have a mass ranging from a few to a few hundred MeV, and an elastic scattering cross section with electrons, photons and/or neutrinos in the 10^{-3}-1  fb range.

  9. Acquired disorders of elastic tissue: part I. Increased elastic tissue and solar elastotic syndromes.

    PubMed

    Lewis, Kevan G; Bercovitch, Lionel; Dill, Sara W; Robinson-Bostom, Leslie

    2004-07-01

    Elastic fibers in the extracellular matrix are an integral component of dermal connective tissue. The resilience and elasticity required for normal structure and function of the skin may be attributed to the network of elastic tissue. Advances in our understanding of elastic tissue physiology provide a foundation for studying the pathogenesis of elastic tissue disorders. Many acquired disorders are nevertheless poorly understood due to the paucity of reported cases. Several acquired disorders in which accumulation or elastotic degeneration of dermal elastic fibers produces prominent clinical and histopathologic features have recently been described. They include elastoderma, linear focal elastosis, and late-onset focal dermal elastosis and must be differentiated from better-known disorders, among them acquired pseudoxanthoma elasticum, elastosis perforans serpiginosa, and Favré-Racouchot syndrome. Learning objective At the conclusion of this learning activity, participants should understand the similarities and differences between acquired disorders of elastic tissue that are characterized by an increase in elastic tissue, as well as the spectrum of solar elastotic dermatoses.

  10. Elastic limit of silicane.

    PubMed

    Peng, Qing; De, Suvranu

    2014-10-21

    Silicane is a fully hydrogenated silicene-a counterpart of graphene-having promising applications in hydrogen storage with capacities larger than 6 wt%. Knowledge of its elastic limit is critical in its applications as well as tailoring its electronic properties by strain. Here we investigate the mechanical response of silicane to various strains using first-principles calculations based on density functional theory. We illustrate that non-linear elastic behavior is prominent in two-dimensional nanomaterials as opposed to bulk materials. The elastic limits defined by ultimate tensile strains are 0.22, 0.28, and 0.25 along armchair, zigzag, and biaxial directions, respectively, an increase of 29%, 33%, and 24% respectively in reference to silicene. The in-plane stiffness and Poisson ratio are reduced by a factor of 16% and 26%, respectively. However, hydrogenation/dehydrogenation has little effect on its ultimate tensile strengths. We obtained high order elastic constants for a rigorous continuum description of the nonlinear elastic response. The limitation of second, third, fourth, and fifth order elastic constants are in the strain range of 0.02, 0.08, and 0.13, and 0.21, respectively. The pressure effect on the second order elastic constants and Poisson's ratio were predicted from the third order elastic constants. Our results could provide a safe guide for promising applications and strain-engineering the functions and properties of silicane monolayers. PMID:25190587

  11. Elastic properties of minerals

    SciTech Connect

    Aleksandrov, K.S.; Prodaivoda, G.T.

    1993-09-01

    Investigations of the elastic properties of the main rock-forming minerals were begun by T.V. Ryzhova and K.S. Aleksandrov over 30 years ago on the initiative of B.P. Belikov. At the time, information on the elasticity of single crystals in general, and especially of minerals, was very scanty. In the surveys of that time there was information on the elasticity of 20 or 30 minerals. These, as a rule, did not include the main rock-forming minerals; silicates were represented only by garnets, quartz, topaz, tourmaline, zircon, beryl, and staurolite, which are often found in nature in the form of large and fairly high-quality crystals. Then and even much later it was still necessary to prove a supposition which now seems obvious: The elastic properties of rocks, and hence the velocities of elastic (seismic) waves in the earth`s crust, are primarily determined by the elastic characteristics of the minerals composing these rocks. Proof of this assertion, with rare exceptions of mono-mineralic rocks (marble, quartzite, etc.) cannot be obtained without information on the elasticities of a sufficiently large number of minerals, primarily framework, layer, and chain silicates which constitute the basis of most rocks. This also served as the starting point and main problem of the undertakings of Aleksandrov, Ryzhova, and Belikov - systematic investigations of the elastic properties of minerals and then of various rocks. 108 refs., 7 tabs.

  12. Elasticity and Geomechanics

    NASA Astrophysics Data System (ADS)

    Davis, R. O.; Selvadurai, A. P. S.

    1996-04-01

    This book concisely examines the use of elasticity in solving geotechnical engineering problems. In a highly illustrated and user-friendly format, it provides a thorough grounding in the linear theory of elasticity and an understanding of the applications. The first two chapters present a basic framework of the theory of elasticity and describe test procedures for the determination of elastic parameters for soils. Chapters 3 and 4 present the fundamental solutions of Boussinesque, Kelvin, and Mindlin, and use these to formulate solutions to problems of practical interest in geotechnical engineering. The book concludes with a sequence of appendices designed to provide the interested student with details of elasticity theory that are peripheral to the main text. Each chapter concludes with a set of questions for the student to answer. The book is appropriate for upper level students in civil engineering and engineering geology.

  13. Measurements of the Differential Cross Sections for the Elastic n-H3 and n-H2 Scattering at 14.1 MeV by Using an Inertial Confinement Fusion Facility

    SciTech Connect

    Frenje, J. A.; Li, C. K.; Seguin, F. H.; Casey, D. T.; Petrasso, R. D.; McNabb, D. P.; Navratil, P.; Quaglioni, S.; Sangster, T. C.; Glebov, V. Y.; Meyerhofer, D. D.

    2011-09-15

    For the first time the differential cross section for the elastic neutron-triton (n-3H) and neutron-deuteron (n-2H) scattering at 14.1 MeV has been measured by using an inertial confinement fusion facility. In these experiments, which were carried out by simultaneously measuring elastically scattered 3H and 2H ions from a deuterium-tritium gas-filled inertial confinement fusion capsule implosion, the differential cross section for the elastic n-3H scattering was obtained with significantly higher accuracy than achieved in previous accelerator experiments. The results compare well with calculations that combine the resonating-group method with an ab initio no-core shell model, which demonstrate that recent advances in ab initio theory can provide an accurate description of light-ion reactions.

  14. Elastic properties of overpressured and unconsolidated sediments

    USGS Publications Warehouse

    Lee, Myung W.

    2003-01-01

    Differential pressure affects elastic velocities and Poisson?s ratio of sediments in such a way that velocities increase as differential pressure increases. Overpressured zones in sediments can be detected by observing an increase in Poisson?s ratio with a corresponding drop in elastic velocities. In highly overpressured sands, such as shallow water flow sands, the P-to S-wave velocity ratio (Vp/Vs) is very high, on the order of 10 or higher, due to the unconsolidated and uncemented nature of sediments. In order to predict elastic characteristics of highly overpressured sands, Biot-Gassmann theory by Lee (BGTL) is used with a variable exponent n that depends on differential pressure and the degree of consolidation/compaction. The exponent n decreases as differential pressure and the degree of consolidation increases, and, as n decreases, velocity increases and Vp/Vs decreases. The predicted velocity ratio by BGTL agrees well with the measured velocity ratio at low differential pressure for unconsolidated sediments.

  15. On granular elasticity

    PubMed Central

    Sun, Qicheng; Jin, Feng; Wang, Guangqian; Song, Shixiong; Zhang, Guohua

    2015-01-01

    Mesoscopic structures form in dense granular materials due to the self-organisation of the constituent particles. These structures have internal structural degrees of freedom in addition to the translational degree of freedom. The resultant granular elasticity, which exhibits intrinsic variations and inevitable relaxation, is a key quantity that accounts for macroscopic solid- or fluid-like properties and the transitions between them. In this work, we propose a potential energy landscape (PEL) with local stable basins and low elastic energy barriers to analyse the nature of granular elasticity. A function for the elastic energy density is proposed for stable states and is further calibrated with ultrasonic measurements. Fluctuations in the elastic energy due to the evolution of internal structures are proposed to describe a so-called configuration temperature Tc as a counterpart of the classical kinetic granular temperature Tk that is attributed to the translational degrees of freedom. The two granular temperatures are chosen as the state variables, and a fundamental equation is established to develop non-equilibrium thermodynamics for granular materials. Due to the relatively low elastic energy barrier in the PEL, granular elasticity relaxes more under common mechanical loadings, and a simple model based on mean-field theory is developed to account for this behaviour. PMID:25951049

  16. Elastic membranes in confinement

    NASA Astrophysics Data System (ADS)

    Bostwick, Joshua; Miksis, Michael; Davis, Stephen

    2014-11-01

    An elastic membrane stretched between two walls takes a shape defined by its length and the volume of fluid it encloses. Many biological structures, such as cells, mitochondria and DNA, have finer internal structure in which a membrane (or elastic member) is geometrically ``confined'' by another object. We study the shape stability of elastic membranes in a ``confining'' box and introduce repulsive van der Waals forces to prevent the membrane from intersecting the wall. We aim to define the parameter space associated with mitochondria-like deformations. We compare the confined to `unconfined' solutions and show how the structure and stability of the membrane shapes changes with the system parameters.

  17. Elastic properties of nanowires

    NASA Astrophysics Data System (ADS)

    da Fonseca, Alexandre F.; Malta, C. P.; Galva~O, Douglas S.

    2006-05-01

    We present a model to study Young's modulus and Poisson's ratio of the composite material of amorphous nanowires. It is an extension of the model derived by two of us [da Fonseca and Galva~o, Phys. Rev. Lett. 92, 175502 (2004)] to study the elastic properties of amorphous nanosprings. The model is based on twisting and tensioning a straight nanowire and we propose an experimental setup to obtain the elastic parameters of the nanowire. We used the Kirchhoff rod model to obtain the expressions for the elastic constants of the nanowire.

  18. Mechanism of Resilin Elasticity

    PubMed Central

    Qin, Guokui; Hu, Xiao; Cebe, Peggy; Kaplan, David L.

    2012-01-01

    Resilin is critical in the flight and jumping systems of insects as a polymeric rubber-like protein with outstanding elasticity. However, insight into the underlying molecular mechanisms responsible for resilin elasticity remains undefined. Here we report the structure and function of resilin from Drosophila CG15920. A reversible beta-turn transition was identified in the peptide encoded by exon III and for full length resilin during energy input and release, features that correlate to the rapid deformation of resilin during functions in vivo. Micellar structures and nano-porous patterns formed after beta-turn structures were present via changes in either the thermal or mechanical inputs. A model is proposed to explain the super elasticity and energy conversion mechanisms of resilin, providing important insight into structure-function relationships for this protein. Further, this model offers a view of elastomeric proteins in general where beta-turn related structures serve as fundamental units of the structure and elasticity. PMID:22893127

  19. Radiance line ratios Ly-β/Ly-α, Ly-γ/Ly-α, Ly-δ/Ly-α, and Ly-ε/Ly-α for soft X-ray emissions following charge exchange between C6+ and Kr

    NASA Astrophysics Data System (ADS)

    Andrianarijaona, V. M.; Wulf, D.; McCammon, D.; Seely, D. G.; Havener, C. C.

    2015-05-01

    The radiance line ratios Ly-β/Ly-α, Ly-γ/Ly-α, Ly-δ/Ly-α, and Ly-ε/Ly-α for soft X-ray emission following charge exchange (CX) between C6+ and Kr are reported for collision energies between approximately 320 and 46,000 eV/u. The corresponding collision velocities (250-3000 km/s) are characteristic of the solar wind. X-ray spectra were obtained at the Oak Ridge National Laboratory Multicharged Ion Research Facility using a microcalorimeter X-ray detector with a resolution on the order of 10 eV FWHM. The measured Ly-ε/Ly-α is zero for all considered energies and suggests that very little, if any, capture to 6p occurs. The measured Ly-β/Ly-α and Ly-γ/Ly-α ratios intersect and form a well resolved node around (950 ± 50) km/s, which could be used as an astrophysical velocity indicative tool. The results reported here are compared to calculations for C6+ + H since no published theory for C6+ + Kr is known to exist. Double-electron-capture (DEC) and other multi-electron processes are possible. True double capture is estimated to be only 10% of the single-electron-capture (SEC).

  20. Deflation of elastic surfaces

    NASA Astrophysics Data System (ADS)

    Quilliet, Catherine; Quemeneur, François; Marmottant, Philippe; Imhof, Arnout; Pépin-Donat, Brigitte; van Blaaderen, Alfons

    2010-03-01

    The deflation of elastic spherical surfaces has been numerically investigated, and show very different types of deformations according the range of elastic parameters, some of them being quantitatively explained through simple calculations. This allows to retrieve various shapes observed on hollow shells (from colloidal to centimeter scale), on lipid vesicles, or on some biological objects. The extension of this process to other geometries allows to modelize vegetal objects such as the ultrafast trap of carnivorous plants.

  1. Elastic Collisions and Gravity

    NASA Astrophysics Data System (ADS)

    Ball, Steven

    2009-04-01

    Elastic collisions are fascinating demonstrations of conservation principles. The mediating force must be conservative in an elastic collision. Truly elastic collisions take place only when the objects in collision do not touch, e.g. magnetic bumpers on low friction carts. This requires that we define a collision as a momentum transfer. Elastic collisions in 1-D can be solved in general and the implications are quite remarkable. For example, a heavy object moving initially towards a light object followed by an elastic collision results in a final velocity of the light object greater than either initial velocity. This is easily demonstrated with low friction carts. Gravitational elastic collisions involving a light spacecraft and an extremely massive body like a moon or planet can be approximated as 1-D collisions, such as the ``free return'' trajectory of Apollo 13 around the moon. The most fascinating gravitational collisions involve the gravitational slingshot effect used to boost spacecraft velocities. The maximum gravitational slingshot effect occurs when approaching a nearly 1-D collision, revealing that the spacecraft can be boosted to greater than twice the planet velocity, enabling the spacecraft to travel much further away from the Sun.

  2. Elasticity of plagioclase feldspars

    NASA Astrophysics Data System (ADS)

    Brown, J. Michael; Angel, Ross J.; Ross, Nancy L.

    2016-02-01

    Elastic properties are reported for eight plagioclase feldspars that span compositions from albite (NaSi3AlO8) to anorthite (CaSi2Al2O8). Surface acoustic wave velocities measured using Impulsive Stimulated Light Scattering and compliance sums from high-pressure X-ray compression studies accurately determine all 21 components of the elasticity tensor for these triclinic minerals. The overall pattern of elasticity and the changes in individual elastic components with composition can be rationalized on the basis of the evolution of crystal structures and chemistry across this solid-solution join. All plagioclase feldspars have high elastic anisotropy; a* (the direction perpendicular to the b and c axes) is the softest direction by a factor of 3 in albite. From albite to anorthite the stiffness of this direction undergoes the greatest change, increasing twofold. Small discontinuities in the elastic components, inferred to occur between the three plagioclase phases with distinct symmetry (C1>¯, I1>¯, and P1>¯), appear consistent with the nature of the underlying conformation of the framework-linked tetrahedra and the associated structural changes. Measured body wave velocities of plagioclase-rich rocks, reported over the last five decades, are consistent with calculated Hill-averaged velocities using the current moduli. This confirms long-standing speculation that previously reported elastic moduli for plagioclase feldspars are systematically in error. The current results provide greater assurance that the seismic structure of the middle and lower crusts can be accurately estimated on the basis of specified mineral modes, chemistry, and fabric.

  3. Charge Exchange with Highly Charged Ions

    NASA Astrophysics Data System (ADS)

    Glick, Jeremy; Ferri, Kevin; Schmitt, Jaclyn; Hanson, Joshua; Marler, Joan

    2016-05-01

    A detailed study of the physics of highly charged ions (HCIs) is critical for a deep understanding of observed phenomena resulting from interactions of HCIs with neutral atoms in astrophysical and fusion environments. Specifically the charge transfer rates and spectroscopy of the subsequent decay fluorescence are of great interest to these communities. Results from a laboratory based investigation of these rates will be presented. The experiment takes advantage of an energy and charge state selected beam of HCIs from the recently on-line Clemson University EBIT (CUEBIT). Progress towards an experimental apparatus for retrapping HCIs towards precision spectroscopy of HCIs will also be presented.

  4. Elastic membranes in confinement.

    PubMed

    Bostwick, J B; Miksis, M J; Davis, S H

    2016-07-01

    An elastic membrane stretched between two walls takes a shape defined by its length and the volume of fluid it encloses. Many biological structures, such as cells, mitochondria and coiled DNA, have fine internal structure in which a membrane (or elastic member) is geometrically 'confined' by another object. Here, the two-dimensional shape of an elastic membrane in a 'confining' box is studied by introducing a repulsive confinement pressure that prevents the membrane from intersecting the wall. The stage is set by contrasting confined and unconfined solutions. Continuation methods are then used to compute response diagrams, from which we identify the particular membrane mechanics that generate mitochondria-like shapes. Large confinement pressures yield complex response diagrams with secondary bifurcations and multiple turning points where modal identities may change. Regions in parameter space where such behaviour occurs are then mapped. PMID:27440257

  5. Elastic anisotropy of crystals

    NASA Astrophysics Data System (ADS)

    Kube, Christopher M.

    2016-09-01

    An anisotropy index seeks to quantify how directionally dependent the properties of a system are. In this article, the focus is on quantifying the elastic anisotropy of crystalline materials. Previous elastic anisotropy indices are reviewed and their shortcomings discussed. A new scalar log-Euclidean anisotropy measure AL is proposed, which overcomes these deficiencies. It is based on a distance measure in a log-Euclidean space applied to fourth-rank elastic tensors. AL is an absolute measure of anisotropy where the limiting case of perfect isotropy yields zero. It is a universal measure of anisotropy applicable to all crystalline materials. Specific examples of strong anisotropy are highlighted. A supplementary material (ftp://ftp.aip.org/epaps/aip_advances/E-AAIDBI-6-041609) provides an anisotropy table giving the values of AL for 2,176 crystallite compounds.

  6. Elastic properties of HMX.

    SciTech Connect

    Sewell, T. D.; Bedrov, D.; Menikoff, Ralph; Smith, G. D.

    2001-01-01

    Atomistic molecular dynamics simulations have been used to calculate isothermal elastic properties for {beta}-, {alpha}-, and {delta}-HMX. The complete elastic tensor for each polymorph was determined at room temperature and pressure via analysis of microscopic strain fluctuations using formalism due to Rahman and Parrinello [J. Chem. Phys. 76,2662 (1982)]. Additionally, the isothermal compression curve was computed for {beta}-HMX for 0 {le} p {le} 10.6 GPa; the bulk modulus K and its pressure derivative K{prime} were obtained from two fitting forms employed previously in experimental studies of the {beta}-HMX equation of state. Overall, the results indicate good agreement between the bulk modulus predicted from the measured and calculated compression curves. The bulk modulus determined directly from the elastic tensor of {beta}-HMX is in significant disagreement with the compression curve-based results. The explanation for this discrepancy is an area of current research.

  7. An elastic second skin

    NASA Astrophysics Data System (ADS)

    Yu, Betty; Kang, Soo-Young; Akthakul, Ariya; Ramadurai, Nithin; Pilkenton, Morgan; Patel, Alpesh; Nashat, Amir; Anderson, Daniel G.; Sakamoto, Fernanda H.; Gilchrest, Barbara A.; Anderson, R. Rox; Langer, Robert

    2016-08-01

    We report the synthesis and application of an elastic, wearable crosslinked polymer layer (XPL) that mimics the properties of normal, youthful skin. XPL is made of a tunable polysiloxane-based material that can be engineered with specific elasticity, contractility, adhesion, tensile strength and occlusivity. XPL can be topically applied, rapidly curing at the skin interface without the need for heat- or light-mediated activation. In a pilot human study, we examined the performance of a prototype XPL that has a tensile modulus matching normal skin responses at low strain (<40%), and that withstands elongations exceeding 250%, elastically recoiling with minimal strain-energy loss on repeated deformation. The application of XPL to the herniated lower eyelid fat pads of 12 subjects resulted in an average 2-grade decrease in herniation appearance in a 5-point severity scale. The XPL platform may offer advanced solutions to compromised skin barrier function, pharmaceutical delivery and wound dressings.

  8. Quantum Critical Elasticity.

    PubMed

    Zacharias, Mario; Paul, Indranil; Garst, Markus

    2015-07-10

    We discuss elastic instabilities of the atomic crystal lattice at zero temperature. Because of long-range shear forces of the solid, at such transitions the phonon velocities vanish, if at all, only along certain crystallographic directions, and, consequently, the critical phonon fluctuations are suppressed to a lower dimensional manifold and governed by a Gaussian fixed point. In the case of symmetry-breaking elastic transitions, a characteristic critical phonon thermodynamics arises that is found, e.g., to violate Debye's T(3) law for the specific heat. We point out that quantum critical elasticity is triggered whenever a critical soft mode couples linearly to the strain tensor. In particular, this is relevant for the electronic Ising-nematic quantum phase transition in a tetragonal crystal as discussed in the context of certain cuprates, ruthenates, and iron-based superconductors. PMID:26207483

  9. Mechanics of elastic networks

    PubMed Central

    Norris, Andrew N.

    2014-01-01

    We consider a periodic lattice structure in d=2 or 3 dimensions with unit cell comprising Z thin elastic members emanating from a similarly situated central node. A general theoretical approach provides an algebraic formula for the effective elasticity of such frameworks. The method yields the effective cubic elastic constants for three-dimensional space-filling lattices with Z=4, 6, 8, 12 and 14, the last being the ‘stiffest’ lattice proposed by Gurtner & Durand (Gurtner & Durand 2014 Proc. R. Soc. A 470, 20130611. (doi:10.1098/rspa.2013.0611)). The analytical expressions provide explicit formulae for the effective properties of pentamode materials, both isotropic and anisotropic, obtained from the general formulation in the stretch-dominated limit for Z=d+1. PMID:25484608

  10. An elastic second skin.

    PubMed

    Yu, Betty; Kang, Soo-Young; Akthakul, Ariya; Ramadurai, Nithin; Pilkenton, Morgan; Patel, Alpesh; Nashat, Amir; Anderson, Daniel G; Sakamoto, Fernanda H; Gilchrest, Barbara A; Anderson, R Rox; Langer, Robert

    2016-08-01

    We report the synthesis and application of an elastic, wearable crosslinked polymer layer (XPL) that mimics the properties of normal, youthful skin. XPL is made of a tunable polysiloxane-based material that can be engineered with specific elasticity, contractility, adhesion, tensile strength and occlusivity. XPL can be topically applied, rapidly curing at the skin interface without the need for heat- or light-mediated activation. In a pilot human study, we examined the performance of a prototype XPL that has a tensile modulus matching normal skin responses at low strain (<40%), and that withstands elongations exceeding 250%, elastically recoiling with minimal strain-energy loss on repeated deformation. The application of XPL to the herniated lower eyelid fat pads of 12 subjects resulted in an average 2-grade decrease in herniation appearance in a 5-point severity scale. The XPL platform may offer advanced solutions to compromised skin barrier function, pharmaceutical delivery and wound dressings. PMID:27159017

  11. Elastic constants of calcite

    USGS Publications Warehouse

    Peselnick, L.; Robie, R.A.

    1962-01-01

    The recent measurements of the elastic constants of calcite by Reddy and Subrahmanyam (1960) disagree with the values obtained independently by Voigt (1910) and Bhimasenachar (1945). The present authors, using an ultrasonic pulse technique at 3 Mc and 25??C, determined the elastic constants of calcite using the exact equations governing the wave velocities in the single crystal. The results are C11=13.7, C33=8.11, C44=3.50, C12=4.82, C13=5.68, and C14=-2.00, in units of 1011 dyncm2. Independent checks of several of the elastic constants were made employing other directions and polarizations of the wave velocities. With the exception of C13, these values substantially agree with the data of Voigt and Bhimasenachar. ?? 1962 The American Institute of Physics.

  12. Mechanics of elastic networks.

    PubMed

    Norris, Andrew N

    2014-12-01

    We consider a periodic lattice structure in d=2 or 3 dimensions with unit cell comprising Z thin elastic members emanating from a similarly situated central node. A general theoretical approach provides an algebraic formula for the effective elasticity of such frameworks. The method yields the effective cubic elastic constants for three-dimensional space-filling lattices with Z=4, 6, 8, 12 and 14, the last being the 'stiffest' lattice proposed by Gurtner & Durand (Gurtner & Durand 2014 Proc. R. Soc. A470, 20130611. (doi:10.1098/rspa.2013.0611)). The analytical expressions provide explicit formulae for the effective properties of pentamode materials, both isotropic and anisotropic, obtained from the general formulation in the stretch-dominated limit for Z=d+1.

  13. The Calculus of Elasticity

    ERIC Educational Resources Information Center

    Gordon, Warren B.

    2006-01-01

    This paper examines the elasticity of demand, and shows that geometrically, it may be interpreted as the ratio of two simple distances along the tangent line: the distance from the point on the curve to the x-intercept to the distance from the point on the curve to the y-intercept. It also shows that total revenue is maximized at the transition…

  14. Elastic and Inelastic Collisions

    ERIC Educational Resources Information Center

    Gluck, Paul

    2010-01-01

    There have been two articles in this journal that described a pair of collision carts used to demonstrate vividly the difference between elastic and inelastic collisions. One cart had a series of washers that were mounted rigidly on a rigid wooden framework, the other had washers mounted on rubber bands stretched across a framework. The rigidly…

  15. The Law of Elasticity

    ERIC Educational Resources Information Center

    Cocco, Alberto; Masin, Sergio Cesare

    2010-01-01

    Participants estimated the imagined elongation of a spring while they were imagining that a load was stretching the spring. This elongation turned out to be a multiplicative function of spring length and load weight--a cognitive law analogous to Hooke's law of elasticity. Participants also estimated the total imagined elongation of springs joined…

  16. Hydrodynamic Elastic Magneto Plastic

    1985-02-01

    The HEMP code solves the conservation equations of two-dimensional elastic-plastic flow, in plane x-y coordinates or in cylindrical symmetry around the x-axis. Provisions for calculation of fixed boundaries, free surfaces, pistons, and boundary slide planes have been included, along with other special conditions.

  17. Frequency dependent elastic impedance inversion for interstratified dispersive elastic parameters

    NASA Astrophysics Data System (ADS)

    Zong, Zhaoyun; Yin, Xingyao; Wu, Guochen

    2016-08-01

    The elastic impedance equation is extended to frequency dependent elastic impedance equation by taking partial derivative to frequency. With this equation as the forward solver, a practical frequency dependent elastic impedance inversion approach is presented to implement the estimation of the interstratified dispersive elastic parameters which makes full use of the frequency information of elastic impedances. Three main steps are included in this approach. Firstly, the elastic Bayesian inversion is implemented for the estimation of elastic impedances from different incident angle. Secondly, with those estimated elastic impedances, their variations are used to estimate P-wave velocity and S-wave velocity. Finally, with the prior elastic impedance and P-wave and S-wave velocity information, the frequency dependent elastic variation with incident angle inversion is presented for the estimation of the interstratified elastic parameters. With this approach, the interstratified elastic parameters rather than the interface information can be estimated, making easier the interpretation of frequency dependent seismic attributes. The model examples illustrate the feasibility and stability of the proposed method in P-wave velocity dispersion and S-wave velocity dispersion estimation. The field data example validates the possibility and efficiency in hydrocarbon indication of the estimated P-wave velocity dispersion and S-wave velocity dispersion.

  18. Elastic platonic shells.

    PubMed

    Yong, Ee Hou; Nelson, David R; Mahadevan, L

    2013-10-25

    On microscopic scales, the crystallinity of flexible tethered or cross-linked membranes determines their mechanical response. We show that by controlling the type, number, and distribution of defects on a spherical elastic shell, it is possible to direct the morphology of these structures. Our numerical simulations show that by deflating a crystalline shell with defects, we can create elastic shell analogs of the classical platonic solids. These morphologies arise via a sharp buckling transition from the sphere which is strongly hysteretic in loading or unloading. We construct a minimal Landau theory for the transition using quadratic and cubic invariants of the spherical harmonic modes. Our approach suggests methods to engineer shape into soft spherical shells using a frozen defect topology.

  19. Elasticity of liquid marbles.

    PubMed

    Asare-Asher, Samuel; Connor, Jason N; Sedev, Rossen

    2015-07-01

    Liquid marbles are liquid droplets covered densely with small particles. They exhibit hydrophobic properties even on hydrophilic surfaces and this behaviour is closely related to the Cassie wetting state and the phenomenon of superhydrophobicity. Typical liquid marbles are of millimetre size but their properties are analogous to smaller capsules and droplets of Pickering emulsions. We study water marbles covered with an uneven multilayer of polyethylene particles. Their elastic properties were assessed under quasi-static conditions. The liquid marbles are highly elastic and can sustain a reversible deformation of up to 30%. The spring constant is of the same order of magnitude as that for bare water droplets. Therefore the elasticity of the liquid marble is provided mainly by the liquid menisci between the particles. Upon further compression, the spring constant increases up to the point of breakage. This increase may be due to capillary attraction acting across the emerging cracks in the particle coating. The stress-strain curve for liquid marbles is similar to that obtained with liquid-filled microcapsules. A mechanical scaling description proposed for capsules is qualitatively applicable for liquid marbles. The exact mechanical role of the multilayer particle network remains elusive.

  20. On the magnetorotational instability and elastic buckling

    PubMed Central

    Vasil, Geoffrey M.

    2015-01-01

    This paper demonstrates an equivalence between rotating magnetized shear flows and a stressed elastic beam. This results from finding the same form of dynamical equations after an asymptotic reduction of the axis-symmetric magnetorotational instability (MRI) under the assumption of almost-critical driving. The analysis considers the MRI dynamics in a non-dissipative near-equilibrium regime. Both the magnetic and elastic systems reduce to a simple one-dimensional wave equation with a non-local nonlinear feedback. Under transformation, the equation comprises a large number of mean-field interacting Duffing oscillators. This system was the first proven example of a strange attractor in a partial differential equation. Finding the same reduced equation in two natural applications suggests the model might result from other applications and could fall into a universal class based on symmetry. PMID:27547088

  1. Stationary patterns in centrifugally driven interfacial elastic fingering.

    PubMed

    Carvalho, Gabriel D; Gadêlha, Hermes; Miranda, José A

    2014-12-01

    A vortex sheet formalism is used to search for equilibrium shapes in the centrifugally driven interfacial elastic fingering problem. We study the development of interfacial instabilities when a viscous fluid surrounded by another of smaller density flows in the confined environment of a rotating Hele-Shaw cell. The peculiarity of the situation is associated to the fact that, due to a chemical reaction, the two-fluid boundary becomes an elastic layer. The interplay between centrifugal and elastic forces leads to the formation of a rich variety of stationary shapes. Visually striking equilibrium morphologies are obtained from the numerical solution of a nonlinear differential equation for the interface curvature (the shape equation), determined by a zero vorticity condition. Classification of the various families of shapes is made via two dimensionless parameters: an effective bending rigidity (ratio of elastic to centrifugal effects) and a geometrical radius of gyration. PMID:25615189

  2. Stationary patterns in centrifugally driven interfacial elastic fingering

    NASA Astrophysics Data System (ADS)

    Carvalho, Gabriel D.; Gadêlha, Hermes; Miranda, José A.

    2014-12-01

    A vortex sheet formalism is used to search for equilibrium shapes in the centrifugally driven interfacial elastic fingering problem. We study the development of interfacial instabilities when a viscous fluid surrounded by another of smaller density flows in the confined environment of a rotating Hele-Shaw cell. The peculiarity of the situation is associated to the fact that, due to a chemical reaction, the two-fluid boundary becomes an elastic layer. The interplay between centrifugal and elastic forces leads to the formation of a rich variety of stationary shapes. Visually striking equilibrium morphologies are obtained from the numerical solution of a nonlinear differential equation for the interface curvature (the shape equation), determined by a zero vorticity condition. Classification of the various families of shapes is made via two dimensionless parameters: an effective bending rigidity (ratio of elastic to centrifugal effects) and a geometrical radius of gyration.

  3. Nucleon elastic form factors

    SciTech Connect

    D. Day

    2007-03-01

    The nucleon form factors are still the subject of active investigation even after an experimental effort spanning 50 years. This is because they are of critical importance to our understanding of the electromagnetic properties of nuclei and provide a unique testing ground for QCD motivated models of nucleon structure. Progress in polarized beams, polarized targets and recoil polarimetry have allowed an important and precise set of data to be collected over the last decade. I will review the experimental status of elastic electron scattering from the nucleon along with an outlook for future progress.

  4. Mobility of a gas-pressurized elastic glove for extravehicular activity

    NASA Astrophysics Data System (ADS)

    Tanaka, Kunihiko; Abe, Chikara; Iwata, Chihiro; Yamagata, Kenji; Murakami, Naoko; Tanaka, Masao; Tanaka, Nobuyuki; Morita, Hironobu

    2010-04-01

    Usability of a gas-pressurized elastic glove for extravehicular activity (EVA) was evaluated by comparing its performance with that of a non-elastic glove like that in the current EVA suit. The right hands of eight healthy volunteers were studied in a chamber. The bare hand at normal ambient pressure, and at -220 mmHg of the chamber pressure (producing the same pressure differential as the current US EVA suit) with each of the gloves. No significant difference in cutaneous blood flow or skin temperature was observed between the gloves. Range of motion (ROM) in the proximal interphalangeal joint of the middle finger with the elastic glove (87.4±4.9°) was significantly wider than that with the non-elastic glove (70.6±2.3°), but the surface electromyography (EMG) amplitude during flexion with the elastic glove was significantly smaller than that with the non-elastic glove (29.3±2.7 mV vs. 46.7±2.3 mV for elastic and non-elastic gloves, respectively). The elastic glove also allowed smaller reduction in grip strength and longer endurance time than the non-elastic glove (-44.3±6.0% vs. -59.4±1.5% from the bare hand grip strength, 26.3±5.7% vs. 10.9±3.1% of the bare hand endurance time, for elastic and non-elastic glove, respectively). The static effects of non-elastic and elastic gloves are similar, but the mobility of the elastic glove is better than that of the non-elastic glove like the one used in the current EVA suit.

  5. Elastic emission polishing

    SciTech Connect

    Loewenthal, M.; Loseke, K.; Dow, T.A.; Scattergood, R.O.

    1988-12-01

    Elastic emission polishing, also called elastic emission machining (EEM), is a process where a stream of abrasive slurry is used to remove material from a substrate and produce damage free surfaces with controlled surface form. It is a noncontacting method utilizing a thick elasto-hydrodynamic film formed between a soft rotating ball and the workpiece to control the flow of the abrasive. An apparatus was built in the Center, which consists of a stationary spindle, a two-axis table for the workpiece, and a pump to circulate the working fluid. The process is controlled by a programmable computer numerical controller (CNC), which presently can operate the spindle speed and movement of the workpiece in one axis only. This apparatus has been used to determine material removal rates on different material samples as a function of time, utilizing zirconium oxide (ZrO{sub 2}) particles suspended in distilled water as the working fluid. By continuing a study of removal rates the process should become predictable, and thus create a new, effective, yet simple tool for ultra-precision mechanical machining of surfaces.

  6. Polysoaps: Configurations and Elasticity

    NASA Astrophysics Data System (ADS)

    Halperin, A.

    1997-03-01

    Simple polymers are very long, flexible, linear molecules. Amphiphiles, soaps, are small molecules comprising of a part that prefers water over oil and a part that prefers oil over water. By combining the two we arrive at an interesting, little explored, class of materials: Polysoaps. These comprise of a water soluble backbone incorporating, at intervals, covalently bound amphiphilic monomers. In water, the polymerised amphiphiles aggregate into self assembled units known as micelles. This induces a dramatic modification of the spatial configurations of the polymers. What were featureless random coils now exhibit intramolecular, hierachial self organisation. Due to this self organisation it is necessary to modify the paradigms describing the large scale behaviour of these polymers: Their configurations, dimensions and elasticity. Understanding the behaviour of these polymers is of practical interest because of their wide range of industrial applications, ranging from cosmetics to paper coating. It is of fundamental interest because polysoaps are characterised by a rugged free energy landscape that is reminiscent of complex systems such as proteins and glasses. The talk concerns theoretical arguments regarding the following issues: (i) The design parameters that govern the spatial configurations of the polysoaps, (ii) The interaction between polysoaps and free amphiphiles, (iii) The effect of the intramolecular self organisation on the elasticity of the chains.

  7. Studies of elastic e-NH3 collisions

    NASA Technical Reports Server (NTRS)

    Pritchard, H. P.; Lima, M. A. P.; Mckoy, V.

    1989-01-01

    Differential and momentum-transfer cross sections for the elastic scattering of electrons by NH3 have been obtained for collision energies of between 2.5 and 20 eV using the fixed-nuclei static-exchange approximation of the Schwinger variational principle. At intermediate and large scattering angles, good agreement is found between calculated and relative experimental cross sections. The differential cross sections reveal evidence of a weak d-wave enhancement around 8 eV.

  8. Design guidance for elastic followup

    SciTech Connect

    Naugle, F.V.

    1983-01-01

    The basic mechanism of elastic followup is discussed in relation to piping design. It is shown how mechanistic insight gained from solutions for a two-bar problem can be used to identify dominant design parameters and to determine appropriate modifications where elastic followup is a potential problem. It is generally recognized that quantitative criteria are needed for elastic followup in the creep range where badly unbalanced lines can pose potential problems. Approaches for criteria development are discussed.

  9. Mathematical Models for Elastic Structures

    NASA Astrophysics Data System (ADS)

    Villaggio, Piero

    1997-10-01

    During the seventeenth century, several useful theories of elastic structures emerged, with applications to civil and mechanical engineering problems. Recent and improved mathematical tools have extended applications into new areas such as mathematical physics, geomechanics, and biomechanics. This book offers a critically filtered collection of the most significant theories dealing with elastic slender bodies. It includes mathematical models involving elastic structures that are used to solve practical problems with particular emphasis on nonlinear problems.

  10. Thermo-elastic behaviour of liquid crystal elastomer

    NASA Astrophysics Data System (ADS)

    J, Jessy P.; Mani, Santosh A.; Amare, Jyoti R.; Gharde, Rita A.

    2015-06-01

    The effect of temperature on Liquid Crystal Elastomer was studied to understand thermo-elastic behaviour of these fantastic soft materials. The investigations were performed using Polarizing Microscopy Studies (PMS) and Differential Thermal Analysis (DTA). The relative length shows hysteresis as function of temperature. As temperature increases, the length shrinks, while it returns to original shape on cooling.

  11. Stress Formulation in Three-Dimensional Elasticity

    NASA Technical Reports Server (NTRS)

    Patnaik, Surya N.; Hopkins, Dale A.

    2001-01-01

    The theory of elasticity evolved over centuries through the contributions of eminent scientists like Cauchy, Navier, Hooke Saint Venant, and others. It was deemed complete when Saint Venant provided the strain formulation in 1860. However, unlike Cauchy, who addressed equilibrium in the field and on the boundary, the strain formulation was confined only to the field. Saint Venant overlooked the compatibility on the boundary. Because of this deficiency, a direct stress formulation could not be developed. Stress with traditional methods must be recovered by backcalculation: differentiating either the displacement or the stress function. We have addressed the compatibility on the boundary. Augmentation of these conditions has completed the stress formulation in elasticity, opening up a way for a direct determination of stress without the intermediate step of calculating the displacement or the stress function. This Completed Beltrami-Michell Formulation (CBMF) can be specialized to derive the traditional methods, but the reverse is not possible. Elasticity solutions must be verified for the compliance of the new equation because the boundary compatibility conditions expressed in terms of displacement are not trivially satisfied. This paper presents the variational derivation of the stress formulation, illustrates the method, examines attributes and benefits, and outlines the future course of research.

  12. Nonlinear elasticity of semiflexible filament networks.

    PubMed

    Meng, Fanlong; Terentjev, Eugene M

    2016-08-10

    We develop a continuum theory for equilibrium elasticity of a network of crosslinked semiflexible filaments, spanning the full range between flexible entropy-driven chains to stiff athermal rods. We choose the 3-chain constitutive model of network elasticity over several plausible candidates, and derive analytical expressions for the elastic energy at arbitrary strain, with the corresponding stress-strain relationship. The theory fits well to a wide range of experimental data on simple shear in different filament networks, quantitatively matching the differential shear modulus variation with stress, with only two adjustable parameters (which represent the filament stiffness and the pre-tension in the network, respectively). The general theory accurately describes the crossover between the positive and negative Poynting effect (normal stress on imposed shear) on increasing the stiffness of filaments forming the network. We discuss the network stability (the point of marginal rigidity) and the phenomenon of tensegrity, showing that filament pre-tension on crosslinking into the network determines the magnitude of linear modulus G0. PMID:27444846

  13. Nonlinear elasticity of semiflexible filament networks.

    PubMed

    Meng, Fanlong; Terentjev, Eugene M

    2016-08-10

    We develop a continuum theory for equilibrium elasticity of a network of crosslinked semiflexible filaments, spanning the full range between flexible entropy-driven chains to stiff athermal rods. We choose the 3-chain constitutive model of network elasticity over several plausible candidates, and derive analytical expressions for the elastic energy at arbitrary strain, with the corresponding stress-strain relationship. The theory fits well to a wide range of experimental data on simple shear in different filament networks, quantitatively matching the differential shear modulus variation with stress, with only two adjustable parameters (which represent the filament stiffness and the pre-tension in the network, respectively). The general theory accurately describes the crossover between the positive and negative Poynting effect (normal stress on imposed shear) on increasing the stiffness of filaments forming the network. We discuss the network stability (the point of marginal rigidity) and the phenomenon of tensegrity, showing that filament pre-tension on crosslinking into the network determines the magnitude of linear modulus G0.

  14. Elasticity of ``Fuzzy'' Biomembranes

    NASA Astrophysics Data System (ADS)

    Evans, E.; Rawicz, W.

    1997-09-01

    Sensitive micropipet methods have been used to measure the elastic stretch modulus and bending rigidity of biomembranes studded with water-soluble polymers. The fully extended lengths of the chemically grafted chains ranged from 10-50× the length of the embedding membrane lipid. Concentrations of the polymer were varied from 1-10× the surface density needed for isolated chains to touch, nominally satisfying the scaling theory requirement for semidilute brushes. Over this range, the membrane stretch modulus was unchanged by the polymer layers, but the bending rigidity increased by as much as 10kBT. Surprisingly, the increase in rigidity deviated significantly from scaling theory predictions, revealing a large marginal brush regime between dilute mushrooms and a semidilute brush.

  15. Elastic recoil detection

    NASA Astrophysics Data System (ADS)

    Bik, W. M. A.; Habraken, F. H. P. M.

    1993-07-01

    In elastic recoil detection (ERD) one determines the yield and energy of particles ejected out of the surface region of samples under MeV ion bombardment. By application of this surface and thin film analysis technique one can obtain quantitative information concerning the depth distribution of light elements in a sample to be analysed. The quantitativity and the depth resolving power are based on knowledge of the recoil cross section and the stopping power of high-energy ions in matter. This paper reviews the fundamentals of this technique and the various experimental methods for recoil identification. Furthermore, important features for material analysis, such as detection limits, depth resolution and elemental range are discussed. Some emphasis is put on the conversion of the spectral contribution of the elements to atomic concentrations in the films for several representative cases. Throughout the review numerous examples are given to illustrate the features of ERD and to demonstrate empirically the accuracy of the quantification method.

  16. The optimal elastic flagellum

    NASA Astrophysics Data System (ADS)

    Spagnolie, Saverio E.; Lauga, Eric

    2010-03-01

    Motile eukaryotic cells propel themselves in viscous fluids by passing waves of bending deformation down their flagella. An infinitely long flagellum achieves a hydrodynamically optimal low-Reynolds number locomotion when the angle between its local tangent and the swimming direction remains constant along its length. Optimal flagella therefore adopt the shape of a helix in three dimensions (smooth) and that of a sawtooth in two dimensions (nonsmooth). Physically, biological organisms (or engineered microswimmers) must expend internal energy in order to produce the waves of deformation responsible for the motion. Here we propose a physically motivated derivation of the optimal flagellum shape. We determine analytically and numerically the shape of the flagellar wave which leads to the fastest swimming for a given appropriately defined energetic expenditure. Our novel approach is to define an energy which includes not only the work against the surrounding fluid, but also (1) the energy stored elastically in the bending of the flagellum, (2) the energy stored elastically in the internal sliding of the polymeric filaments which are responsible for the generation of the bending waves (microtubules), and (3) the viscous dissipation due to the presence of an internal fluid. This approach regularizes the optimal sawtooth shape for two-dimensional deformation at the expense of a small loss in hydrodynamic efficiency. The optimal waveforms of finite-size flagella are shown to depend on a competition between rotational motions and bending costs, and we observe a surprising bias toward half-integer wave numbers. Their final hydrodynamic efficiencies are above 6%, significantly larger than those of swimming cells, therefore indicating available room for further biological tuning.

  17. Elastic model of dry friction

    SciTech Connect

    Larkin, A. I.; Khmelnitskii, D. E.

    2013-09-15

    Friction of elastic bodies is connected with the passing through the metastable states that arise at the contact of surfaces rubbing against each other. Three models are considered that give rise to the metastable states. Friction forces and their dependence on the pressure are calculated. In Appendix A, the contact problem of elasticity theory is solved with adhesion taken into account.

  18. The First Law of Elasticity

    ERIC Educational Resources Information Center

    Girill, T. R.

    1972-01-01

    The Boyle-Mariotte gas law was formulated in terms of pneumatic springs," subsumed by Hooke under his own stress-strain relation, and generally regarded as a law of elasticity. The subsequent development of Boyle's principle and elasticity provide thought-provoking test cases for Kuhn's notations of paradigm and puzzle solving in physics.…

  19. Programmable shape transformation of elastic spherical domes.

    PubMed

    Abdullah, Arif M; Braun, Paul V; Hsia, K Jimmy

    2016-07-20

    We investigate mismatch strain driven programmable shape transformation of spherical domes and report the effects of different geometric and structural characteristics on dome behavior in response to applied mismatch strain. We envision a bilayer dome design where the differential swelling of the inner layer with respect to the passive outer layer in response to changes in dome surroundings (such as the introduction of an organic solvent) introduces mismatch strain within the bilayer system and causes dome shape transformation. Finite element analysis reveals that, in addition to snap-through, spherical domes undergo bifurcation buckling and eventually gradual bending to morph into cylinders with increasing mismatch strain. Besides demonstrating how the snap-through energy barrier depends on the spherical dome shape, our analysis identifies three distinct groups of dome geometries based on their mismatch strain-transformed configuration relationships. Our experiments with polymer-based elastic bilayer domes that exhibit differential swelling in organic solvents qualitatively confirm the finite element predictions. We establish that, in addition to externally applied stimuli (mismatch strain), bilayer spherical dome morphing can be tuned and hence programmed through its geometry and structural characteristics. Incorporation of an elastic instability mechanism such as snap-through within the framework of stimuli-responsive functional devices can improve their response time which is otherwise controlled by diffusion. Hence, our proposed design guidelines can be used to realize deployable, multi-functional, reconfigurable, and therefore, adaptive structures responsive to a diverse set of stimuli across multiple length scales.

  20. Elasticity theory of smectic and canonic mesophases

    SciTech Connect

    Stallinga, S.; Vertogen, G. )

    1995-01-01

    The general theory of elasticity for smectic and canonic mesophases is formulated, starting from the assumption that the equilibrium state is spatially periodic. The various surface terms appearing in the deformation free energy density are considered as well. The effective description of the elastic behavior of a general nonchiral smectic mesophase involves one positional elastic constant, 16 bulk orientational elastic constants, and six surface orientational elastic constants. One additional bulk orientational elastic constant is required for the description of a general chiral smectic mesophase. The effective description of the elastic behavior of a general nonchiral canonic mesophase involves six positional elastic constants and three bulk orientational elastic constants. In this case the property of chirality does not introduce additional orientational elastic constants. The elastic constants for some relevant smectic and canonic mesophases are given, including the elastic constants for the antiferroelectric Sm-[ital C][sub [ital A

  1. Elastic scattering of electrons from Rb, Cs and Fr atoms

    NASA Astrophysics Data System (ADS)

    Gangwar, R. K.; Tripathi, A. N.; Sharma, L.; Srivastava, R.

    2010-04-01

    Differential, integrated elastic, momentum-transfer and total cross sections as well as differential S, T and U spin parameters for scattering of electrons from rubidium, caesium and francium atoms in the incident energy range up to 300 eV are calculated using a relativistic Dirac equation. The projectile electron-target atom interaction is represented by both real and complex parameter-free optical potentials for obtaining the solution of a Dirac equation for scattered electrons. The Dirac-Fock wavefunctions have been used to represent the Rb, Cs and Fr target atoms. The results of differential cross sections and spin asymmetry parameter S for e-Rb and e-Cs have been compared with the available experimental and theoretical results. Detailed results are reported for the elastic scattering of electrons from the ground states of a francium atom for the first time in the wide range of incident electron energies. The results of electron-Fr elastic scattering show the similar features to those obtained in the case of e-Rb and e-Cs elastic scattering.

  2. Skin blood flow with elastic compressive extravehicular activity space suit.

    PubMed

    Tanaka, Kunihiko; Gotoh, Taro M; Morita, Hironobu; Hargens, Alan R

    2003-10-01

    During extravehicular activity (EVA), current space suits are pressurized with 100% oxygen at approximately 222 mmHg. A tight elastic garment, or mechanical counter pressure (MCP) suit that generates pressure by compression, may have several advantages over current space suit technology. In this study, we investigated local microcirculatory effects produced with negative ambient pressure with an MCP sleeve. The MCP glove and sleeve generated pressures similar to the current space suit. MCP remained constant during negative pressure due to unchanged elasticity of the material. Decreased skin capillary blood flow and temperature during MCP compression was counteracted by greater negative pressure or a smaller pressure differential.

  3. Calcification of medial elastic fibers and aortic elasticity.

    PubMed

    Niederhoffer, N; Lartaud-Idjouadiene, I; Giummelly, P; Duvivier, C; Peslin, R; Atkinson, J

    1997-04-01

    We tested the hypothesis that a simple change in wall composition (medial calcium overload of elastic fibers) can decrease aortic elasticity. Calcium overload was produced by hypervitaminosis D plus nicotine (VDN) in the young rat. Two months later, measurement of central aortic mean blood pressure in the unanesthetized, unrestrained rat showed that the VDN rat suffered from isolated systolic hypertension but that mean blood pressure was normal. Wall thickness and internal diameter determined after in situ pressurized fixation were unchanged, as was calculated wall stress. Wall stiffness was estimated from (1) elastic modulus (determined with the Moens-Korteweg equation and values for aortic pulse wave velocity in the unanesthetized, unrestrained rat and arterial dimensions) and (2) isobaric elasticity (= slope relating pulse wave velocity to mean intraluminal pressure in the phenylephrine-infused, pithed rat preparation). Both increased after VDN, and both were significantly correlated to the wall content of calcium and the elastin-specific amino acids desmosine and isodesmosine. Left ventricular hypertrophy occurred in the VDN model, and left ventricular mass was related to isobaric elasticity. In conclusion, elastocalcinosis induces destruction of elastic fibers, which leads to arterial stiffness, and the latter may be involved in the development of left ventricular hypertrophy in a normotensive model.

  4. Differential cross section for π-p-->γn from 427 to 625 MeV/c

    NASA Astrophysics Data System (ADS)

    Kim, G. J.; Arends, J.; Briscoe, W. J.; Engelage, J.; Nefkens, B. M. K.; Sadler, M. E.; Ziock, H. J.

    1989-07-01

    Differential cross sections for π-p-->γn have been determined from 427 to 625 MeV/c, mainly at 90° and 110° c.m. The data were obtained by combining measurements of the Panofsky ratio in flight with known charge-exchange cross sections. The results are compared with γn-->π-p data derived from γd experiments; the difference is typically 30%. The radiative decay amplitudes of neutral πN resonances are therefore uncertain by at least 30%.

  5. Flame resistant elastic elastomeric fibers

    NASA Technical Reports Server (NTRS)

    Howarth, J. T.; Massucco, A. A.

    1972-01-01

    Development of materials to improve flame resistance of elastic elastomeric fibers is discussed. Two approaches, synthesis of polyether based urethanes and modification of synthesized urethanes with flame ratardant additives, are described. Specific applications of both techniques are presented.

  6. Measuring How Elastic Arteries Function.

    ERIC Educational Resources Information Center

    DeMont, M. Edwin; MacGillivray, Patrick S.; Davison, Ian G.; McConnell, Colin J.

    1997-01-01

    Describes a procedure used to measure force and pressure in elastic arteries. Discusses the physics of the procedure and recommends the use of bovine arteries. Explains the preparation of the arteries for the procedure. (DDR)

  7. Elasticity of crystalline molecular explosives

    SciTech Connect

    Hooks, Daniel E.; Ramos, Kyle J.; Bolme, C. A.; Cawkwell, Marc J.

    2015-04-14

    Crystalline molecular explosives are key components of engineered explosive formulations. In precision applications a high degree of consistency and predictability is desired under a range of conditions to a variety of stimuli. Prediction of behaviors from mechanical response and failure to detonation initiation and detonation performance of the material is linked to accurate knowledge of the material structure and first stage of deformation: elasticity. The elastic response of pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX), and cyclotetramethylene tetranitramine (HMX), including aspects of material and measurement variability, and computational methods are described in detail. Experimental determinations of elastic tensors are compared, and an evaluation of sources of error is presented. Furthermore, computed elastic constants are also compared for these materials and for triaminotrinitrobenzene (TATB), for which there are no measurements.

  8. Elasticity of crystalline molecular explosives

    DOE PAGESBeta

    Hooks, Daniel E.; Ramos, Kyle J.; Bolme, C. A.; Cawkwell, Marc J.

    2015-04-14

    Crystalline molecular explosives are key components of engineered explosive formulations. In precision applications a high degree of consistency and predictability is desired under a range of conditions to a variety of stimuli. Prediction of behaviors from mechanical response and failure to detonation initiation and detonation performance of the material is linked to accurate knowledge of the material structure and first stage of deformation: elasticity. The elastic response of pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX), and cyclotetramethylene tetranitramine (HMX), including aspects of material and measurement variability, and computational methods are described in detail. Experimental determinations of elastic tensors are compared, andmore » an evaluation of sources of error is presented. Furthermore, computed elastic constants are also compared for these materials and for triaminotrinitrobenzene (TATB), for which there are no measurements.« less

  9. Elastic protectors for ultrasound injection

    SciTech Connect

    Barkhatov, V.A.; Nesterova, L.A.

    1995-07-01

    A new material has been developed for elastic protectors on ultrasonic probes: sonar rubber. This combines low ultrasonic absorption, high strength, and wear resistance, and so the rubber can be used in sensor designs.

  10. Elastic Properties of Mantle Minerals

    NASA Astrophysics Data System (ADS)

    Duffy, T. S.; Stan, C. V.

    2012-12-01

    The most direct information about the interior structure of the Earth comes from seismic wave velocities. Interpretation of seismic data requires an understanding of how sound velocities and elastic properties of minerals vary with pressure, temperature, crystal structure, and composition as well as the role of anelasticity, melts, etc. More generally, elastic moduli are important for understanding many solid-state phenomena including mechanical stability, interatomic interactions, material strength, compressibility, and phase transition mechanisms. The database of mineral elasticity measurements has been growing rapidly in recent years. In this work, we report initial results of an ongoing survey of our current knowledge of mineral elasticity at both ambient conditions and high pressures and temperatures. The analysis is selective, emphasizing single crystal measurements but also incorporating polycrystalline measurements and volume compression data as appropriate. The goal is to synthesize our current understanding of mineral elasticity in terms of structure and composition, and to identify the major remaining needs for experimental and theoretical work. Clinopyroxenes (Cpx) provide an example of our approach. A wide range of clinopyroxene compositions are found geologically and Mg-, Ca-, and Na-rich clinopyroxenes are expected to be important components in the upper mantle. The single-crystal elastic properties of a number of endmember Cpx compositions have been measured and these exhibit a range of ~25% in shear velocity. Those with monovalent cations (spodumene, jadeite) in the M2 site exhibit the highest velocities while Fe-rich (hendenbergit, acmite) compositions have the lowest velocities. The effects on velocity due to a wide range of chemical substitutions can be defined, but there are important discrepancies and omissions in the database. New measurements of omphacites, intermediate diopside-hedenbergite compositions, aegerine/acmite, augite, etc. are

  11. Do we understand elastic scattering up to LHC energies?

    NASA Astrophysics Data System (ADS)

    Soffer, Jacques

    2013-04-01

    The measurements of high energy ¯pp and pp elastic at ISR, SPS, and Tevatron colliders have provided usefull informations on the behavior of the scattering amplitude. A large step in energy domain is accomplished with the LHC collider presently running, giving a unique opportunity to improve our knowledge on the asymptotic regime of the elastic scattering amplitude and to verify the validity of our theoretical approach, to describe the total cross section σtot(s), the total elastic cross section σel(s), the ratio of the real to imaginary parts of the forward amplitude ρ(s) and the differential cross section dσ (s,t)/dt.

  12. Mathematical modeling of spinning elastic bodies for modal analysis.

    NASA Technical Reports Server (NTRS)

    Likins, P. W.; Barbera, F. J.; Baddeley, V.

    1973-01-01

    The problem of modal analysis of an elastic appendage on a rotating base is examined to establish the relative advantages of various mathematical models of elastic structures and to extract general inferences concerning the magnitude and character of the influence of spin on the natural frequencies and mode shapes of rotating structures. In realization of the first objective, it is concluded that except for a small class of very special cases the elastic continuum model is devoid of useful results, while for constant nominal spin rate the distributed-mass finite-element model is quite generally tractable, since in the latter case the governing equations are always linear, constant-coefficient, ordinary differential equations. Although with both of these alternatives the details of the formulation generally obscure the essence of the problem and permit very little engineering insight to be gained without extensive computation, this difficulty is not encountered when dealing with simple concentrated mass models.

  13. Effects of nanosecond pulse electric fields on cellular elasticity.

    PubMed

    Dutta, Diganta; Asmar, Anthony; Stacey, Michael

    2015-05-01

    We investigated the effects of a single 60 nanosecond pulsed electric field (nsPEF) of low (15 kV/cm) and high (60 kV/cm) field strengths on cellular morphology and membrane elasticity in Jurkat cells using fluorescent microscopy and atomic force microscopy (AFM). We performed force displacement measurements on cells using AFM and calculated the Young's modulus for membrane elasticity. Differential effects were observed depending upon pulsing conditions. We found that a single nsPEF of low field strength did not induce any apparent cytoskeletal breakdown and had minor morphological changes. Interestingly, force measurements and calculation of Young's modulus showed a significant decrease in membrane elasticity. A single nsPEF of high field strength induced stark morphological changes due to disruption of the actin cytoskeleton and a marked decrease in elasticity likely caused by irreversible membrane damage. We suggest that the cellular morphology is mainly dependent on stabilization by the actin cytoskeleton, while the elasticity changes are partially dependent on the cytoskeletal integrity.

  14. Models for elastic shells with incompatible strains

    PubMed Central

    Lewicka, Marta; Mahadevan, L.; Pakzad, Mohammad Reza

    2014-01-01

    The three-dimensional shapes of thin lamina, such as leaves, flowers, feathers, wings, etc., are driven by the differential strain induced by the relative growth. The growth takes place through variations in the Riemannian metric given on the thin sheet as a function of location in the central plane and also across its thickness. The shape is then a consequence of elastic energy minimization on the frustrated geometrical object. Here, we provide a rigorous derivation of the asymptotic theories for shapes of residually strained thin lamina with non-trivial curvatures, i.e. growing elastic shells in both the weakly and strongly curved regimes, generalizing earlier results for the growth of nominally flat plates. The different theories are distinguished by the scaling of the mid-surface curvature relative to the inverse thickness and growth strain, and also allow us to generalize the classical Föppl–von Kármán energy to theories of prestrained shallow shells. PMID:24808750

  15. Variational calculation of electron elastic scattering by atomic helium

    NASA Astrophysics Data System (ADS)

    Chernek, P. J.

    1982-12-01

    The elastic-scattering of electrons from atomic helium in the ground state is investigated. It is shown that for low energy incident electrons the scattering problem reduced to solving an ordinary integro-differential equation for the scattering wave-function. A method is discussed to obtain approximate solutions to the integro-differential equation by variational principles. The extremum condition of the variational method is formulated into a general N x N matrix equation which reduces to a 2 x 2 eigen-value matrix problem for the phase-shift of the scattering electron. An algorithm is presented to obtain the collisional cross-section for elastic scattering as a function of incident electron energy.

  16. Nonlocal three-dimensional theory of elasticity with application to free vibration of functionally graded nanoplates on elastic foundations

    NASA Astrophysics Data System (ADS)

    Ansari, R.; Shahabodini, A.; Faghih Shojaei, M.

    2016-02-01

    In the present work, a three-dimensional (3D) elastic plate model capturing the small scale effects is developed for the free vibration of functionally graded (FG) nanoplates resting on elastic foundations. The theoretical model is formulated employing the nonlocal differential constitutive relations of Eringen in conjunction with the 3D equations of motion of elasticity.The material properties are assumed to vary continuously along the thickness of the nanoplate in accordance with the power law formulation. Through extending the generalized differential quadrature (GDQ) method to the three-dimensional case, the governing equations are simultaneously discretized in every three coordinate directions and are then recast to the standard form of an eigen value problem. Solving the acquired problem, the natural frequencies of the nanoplates with different boundary conditions are calculated. The convergence behavior of the numerical results is checked out and comparison studies are conducted to make sure of the accuracy and reliability of the present model. Finally, the dependence of the vibration behavior of the nanoplate on edge conditions, elastic coefficients of the foundation, scale coefficient, mode number, material and geometric parameters are discussed.

  17. Buckling modes of elastic thin films on elastic substrates

    NASA Astrophysics Data System (ADS)

    Mei, Haixia; Huang, Rui; Chung, Jun Young; Stafford, Christopher M.; Yu, Hong-Hui

    2007-04-01

    Two buckling modes have been observed in thin films: buckle delamination and wrinkling. This letter identifies the conditions for selecting the favored buckling modes for elastic films on elastic substrates. Transition from one buckling mode to another is predicted as the stiffness ratio between the substrate and the film or is predicted for variation of the stiffness ratio between the substrate and the film or variation of theinterfacial defect size. The theoretical results are demonstrated experimentally by observing the coexistence of both buckling modes and mode transition in one film-substrate system.

  18. Elastically deformable 3D organs for haptic surgical simulation.

    PubMed

    Webster, Roger; Haluck, Randy; Ravenscroft, Rob; Mohler, Betty; Crouthamel, Eric; Frack, Tyson; Terlecki, Steve; Sheaffer, Jeremy

    2002-01-01

    This paper describes a technique for incorporating real-time elastically deformable 3D organs in haptic surgical simulators. Our system is a physically based particle model utilizing a mass-springs-damper connectivity with an implicit predictor to speed up calculations during each time step. The solution involves repeated application of Newton's 2ndd Law of motion: F = ma using an implicit solver for numerically solving the differential equations.

  19. Neutral Current Elastic Interactions in MiniBooNE

    SciTech Connect

    Dharmapalan, Ranjan; /Alabama U.

    2011-10-01

    Neutral Current Elastic (NCE) interactions in MiniBooNE are discussed. In the neutrino mode MiniBooNE reported: the flux averaged NCE differential cross section as a function of four-momentum transferred squared, an axial mass (M{sub A}) measurement, and a measurement of the strange quark spin content of the nucleon, {Delta}s. In the antineutrino mode we present the background-subtracted data which is compared with the Monte Carlo predictions.

  20. Mapping Elasticity at the Nanoscale

    NASA Astrophysics Data System (ADS)

    Stan, Gheorghe; Price, William

    2006-03-01

    In the last few years Atomic Force Acoustic Microscopy has been developed to investigate the elastic response of materials at the nanoscale ^[1],[2]. We have extended this technique to the real-time mapping of nanomechanical properties of material surfaces. This mapping allows us to investigate the local variation of elastic properties with nanometer resolution and to reduce the uncertainties that arise from single measurements. Quantitative measurements are acquired by first performing an accurate calibration of the elastic properties of the Atomic Force Microscope’s probes with respect to single crystal reference materials. A wide variety of surfaces with different mechanical properties have been investigated to illustrate the applicability of this technique. ^[1] U. Rabe et al., Surf. Interface Anal. 33 , 65 (2002)^[2] D.C. Hurley et al., J. Appl. Phys. 94, 2347 (2003)

  1. Biodegradable stents with elastic memory.

    PubMed

    Venkatraman, Subbu S; Tan, Lay Poh; Joso, Joe Ferry D; Boey, Yin Chiang Freddy; Wang, Xintong

    2006-03-01

    This work reports, for the first time, the development of a fully biodegradable polymeric stent that can self-expand at body temperatures (approximately 37 degrees C), using the concept of elastic memory. This self-expansion is necessary in fully polymeric stents, to overcome the problem of elastic recoil following balloon expansion in a body vessel. Bi-layered biodegradable stent prototypes were produced from poly-L-lactic acid (PLLA) and poly glycolic acid (PLGA) polymers. Elastic memory was imparted to the stents by temperature conditioning. The thickness and composition of each layer in the stents are critical parameters that affect the rate of self-expansion at 37 degrees C, as well as the collapse strengths of the stents. The rate of self-expansion of the stents, as measured at 37 degrees C, exhibits a maximum with layer thickness. The Tg of the outer layer is another significant parameter that affects the overall rate of expansion.

  2. Price and Income Elasticities of Iranian Exports

    NASA Astrophysics Data System (ADS)

    Atrkar Roshan, Sedigheh

    This study investigates the export demand elasticities at the aggregate and disaggregated levels over the period 1977 to 2001 for Iran. By utilizing an export demand model and using time series techniques that account for the nonstationarity in the data, the price and income elasticities of demand are estimated by commodity class. As the elasticities of demand for various categories of exports are different, while they are crucial for policy determination. Based upon the estimated results, price and income elasticities are almost similar to those obtained in earlier studies in the case of developing countries. The main findings of this paper demonstrate that, price elasticities are smaller than -1 for all exports categories, whereas the income elasticities are found to be greater than one. The results also suggested, the income elasticities of industrial goods are higher compared to other export categories, while the lower elasticities are found in primary exports. The price and income elasticity estimates have also good statistical properties.

  3. Thermal fluctuations and rubber elasticity.

    PubMed

    Xing, Xiangjun; Goldbart, Paul M; Radzihovsky, Leo

    2007-02-16

    The effects of thermal elastic fluctuations in rubbery materials are examined. It is shown that, due to their interplay with the incompressibility constraint, these fluctuations qualitatively modify the large-deformation stress-strain relation, compared to that of classical rubber elasticity. To leading order, this mechanism provides a simple and generic explanation for the peak structure of Mooney-Rivlin stress-strain relation and shows good agreement with experiments. It also leads to the prediction of a phonon correlation function that depends on the external deformation. PMID:17359034

  4. Thermal Fluctuations and Rubber Elasticity

    NASA Astrophysics Data System (ADS)

    Xing, Xiangjun; Goldbart, Paul M.; Radzihovsky, Leo

    2007-02-01

    The effects of thermal elastic fluctuations in rubbery materials are examined. It is shown that, due to their interplay with the incompressibility constraint, these fluctuations qualitatively modify the large-deformation stress-strain relation, compared to that of classical rubber elasticity. To leading order, this mechanism provides a simple and generic explanation for the peak structure of Mooney-Rivlin stress-strain relation and shows good agreement with experiments. It also leads to the prediction of a phonon correlation function that depends on the external deformation.

  5. Cellular Uptake of Elastic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Yi, Xin; Shi, Xinghua; Gao, Huajian

    2011-08-01

    A fundamental understanding of cell-nanomaterial interaction is of essential importance to nanomedicine and safe applications of nanotechnology. Here we investigate the adhesive wrapping of a soft elastic vesicle by a lipid membrane. We show that there exist a maximum of five distinct wrapping phases based on the stability of full wrapping, partial wrapping, and no wrapping states. The wrapping phases depend on the vesicle size, adhesion energy, surface tension of membrane, and bending rigidity ratio between vesicle and membrane. These results are of immediate interest to the study of vesicular transport and endocytosis or phagocytosis of elastic particles into cells.

  6. Elastic constants for 8-OCB

    NASA Astrophysics Data System (ADS)

    Czechowski, Grzegorz; Zywucki, B.; Jadzyn, Jan

    1993-10-01

    The Frederiks transitions for the n-octyloxycyanobiphenyl (8-OCB) placed in the external magnetic and electric field as a function of the temperature have been studied. On the basis of threshold values Bc and Uc, the elastic constants for splay, bend and twist modes are determined. The magnetic anisotropy of 8-OCB as a function of temperature has been determined. The K11 and K33 elastic constants show the pretransitional nematic- smectic A effect. The values of critical exponents obtained from the temperature dependence of K11 and K33 in the vicinity of N-SA phase transition are discussed.

  7. Mesenchymal stem cells display different gene expression profiles compared to hyaline and elastic chondrocytes

    PubMed Central

    Zhai, Li-Jie; Zhao, Ke-Qing; Wang, Zhi-Qiang; Feng, Ya; Xing, Shuang-Chun

    2011-01-01

    Cartilage has a poor intrinsic repair capacity, requiring surgical intervention to effect biological repair. Tissue engineering technologies or regenerative medicine strategies are currently being employed to address cartilage repair. Mesenchymal stem cells (MSCs) are considered to be an excellent cell source for this application. However, the different gene expression profiles between the MSCs and differentiated cartilage remain unclear. In this report, we first examined the gene expression profiles between the MSCs, hyaline and elastic chondrocytes, and then identify candidate genes, which may be important in the process of MSC differentiation into hyaline and elastic cartilage. Several hundred differentially expressed genes were screened initially by microarray, including 417 simultaneously up-regulated genes in both hyaline and elastic chondrocytes, with 313 down-regulated genes. Several genes were identified that were up-regulated in hyaline chondrocytes while down-regulated in elastic chondrocytes. Both RT-PCR and western blot analysis were consistent with those results obtained by microarray analysis. Chondromodulinl (Chm1) was found to be highly expressed in MSCs differentiating to hyaline and elastic cartilage. Both collagen type II, alpha 1 (Col2a1) and cartilage homeo protein 1 (Cart1) were also highly upregulated and may be important early differentiation of MSCs to hyaline cartilage. PMID:21394289

  8. P(P bar)P elastic scattering and cosmic ray data

    NASA Technical Reports Server (NTRS)

    FAZAL-E-ALEEM; Saleem, M.

    1985-01-01

    It is shown that the total cross section for pp elastic scattering at cosmic ray energies, as well as the total cross section, the slope parameter b(s,t) and the differential cross section for small momentum transfer at ISR and collider energies for p(p)p elastic scattering can be simultaneously fitted by using a simple Regge pole model. The results of this theory is discussed in detail.

  9. Elastic modes and their computation

    SciTech Connect

    Hedstrom, G.W.

    1995-04-01

    In this note we summarize the theory of modes in stratified elastic media, and we discuss some of the considerations necessary to achieve reliable numerical computations. We also point out the consequences of the fact that the corresponding eigenvalue problem is not selfadjoint. 14 refs.

  10. Elastic forward scattering of gluons

    NASA Astrophysics Data System (ADS)

    Ermolaev, B. I.

    1995-06-01

    The colour octet and singlet parts of the elastic gg→ gg-scattering amplitude are evaluated in the Regge kinematical region s≫- t in the LLA, with iπ-terms taken into account, by constructing and solving a set of the infrared evolution equations.

  11. Pilot Study of Debt Elasticity

    ERIC Educational Resources Information Center

    Greiner, Keith; Girardi, Tony

    2006-01-01

    This report examines the relationship between student loan debt and the manner in which that debt is described. It focuses on three forms of description: (1) monthly payments, (2) total debt, and (3) income after graduation. The authors used the term elasticity to describe the relationship between consumers' college choices and the retention…

  12. HEMP. Hydrodynamic Elastic Magneto Plastic

    SciTech Connect

    Wilkins, M.L.; Levatin, J.A.

    1985-02-01

    The HEMP code solves the conservation equations of two-dimensional elastic-plastic flow, in plane x-y coordinates or in cylindrical symmetry around the x-axis. Provisions for calculation of fixed boundaries, free surfaces, pistons, and boundary slide planes have been included, along with other special conditions.

  13. Duration of an Elastic Collision

    ERIC Educational Resources Information Center

    de Izarra, Charles

    2012-01-01

    With a pedagogical goal, this paper deals with a study of the duration of an elastic collision of an inflatable spherical ball on a planar surface suitable for undergraduate studies. First, the force generated by the deformed spherical ball is obtained under assumptions that are discussed. The study of the motion of the spherical ball colliding…

  14. Elastic And Plastic Deformations In Butt Welds

    NASA Technical Reports Server (NTRS)

    Verderaime, V.

    1992-01-01

    Report presents study of mathematical modeling of stresses and strains, reaching beyond limits of elasticity, in bars and plates. Study oriented toward development of capability to predict stresses and resulting elastic and plastic strains in butt welds.

  15. Low-Energy Elastic Electron Scattering by Atomic Oxygen

    NASA Technical Reports Server (NTRS)

    Zatsarinny O.; Bartschat, K.; Tayal, S. S.

    2006-01-01

    The B-spline R-matrix method is employed to investigate the low-energy elastic electron scattering by atomic oxygen. Flexible non-orthogonal sets of radial functions are used to construct the target description and to represent the scattering functions. A detailed investigation regarding the dependence of the predicted partial and total cross sections on the scattering model and the accuracy of the target description is presented. The predicted angle-integrated elastic cross sections are in good agreement with experiment, whereas significant discrepancies are found in the angle-differential elastic cross sections near the forward direction. .The near-threshold results are found to strongly depend on the treatment of inner-core short-range correlation effects in the target description, as well as on a proper account of the target polarizability. A sharp increase in the elastic cross sections below 1 eV found in some earlier calculations is judged to be an artifact of an unbalanced description of correlation in the N-electron target structure and the (N+l)-electron-collision problems.

  16. Nonlinear elastic properties of particulate composites

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Chao; Jiang, Xiaohu

    1993-07-01

    A METHOD of computing effective elastic moduli of isotropic nonlinear composites is developed by using a perturbation scheme. It is demonstrated that only solutions from linear elasticity are needed in computing higher order moduli. As an application of the method, particulate composites of nonlinear elastic materials are analysed.

  17. Elasticity-based identification of tumor margins using Brillouin spectroscopy

    NASA Astrophysics Data System (ADS)

    Troyanova-Wood, Maria; Meng, Zhaokai; Yakovlev, Vladislav V.

    2016-03-01

    The purpose of this study is to demonstrate the efficacy of using Brillouin spectroscopy for differentiation between healthy and cancerous tissues. Previous studies of various cancers indicate that elasticity of the tumor differs from that of the surrounding tissue. We hypothesize that it is possible to distinguish between normal and malignant areas based on their Brillouin measurements. Brillouin spectroscopy is an emerging spectroscopic technique capable of assessing the local elasticity of samples by measuring the Brillouin shift. In the present study, we have used malignant melanoma tissue samples from Sinclair miniature swine to demonstrate the validity of our proposed application. We performed Brillouin measurements on healthy tissue, normal tumor and regressing tumor (as indicated by depigmentation of tissue). Overall, the tumors were found to be stiffer than the surrounding healthy tissue. However, the regressing tumor displayed the elastic properties closer to that of the healthy tissue. Based on the Brillouin measurements, we have successfully differentiated between the tumor and healthy tissues with a high degree of confidence (p<104 for normal tumor, p<0.05 for regressing tumor). Our results indicate that Brillouin spectroscopy is an appropriate tool to not only pinpoint tumor boundaries, but also to monitor tumor growth or evaluate its response to treatment.

  18. Linear elastic fracture mechanics primer

    NASA Technical Reports Server (NTRS)

    Wilson, Christopher D.

    1992-01-01

    This primer is intended to remove the blackbox perception of fracture mechanics computer software by structural engineers. The fundamental concepts of linear elastic fracture mechanics are presented with emphasis on the practical application of fracture mechanics to real problems. Numerous rules of thumb are provided. Recommended texts for additional reading, and a discussion of the significance of fracture mechanics in structural design are given. Griffith's criterion for crack extension, Irwin's elastic stress field near the crack tip, and the influence of small-scale plasticity are discussed. Common stress intensities factor solutions and methods for determining them are included. Fracture toughness and subcritical crack growth are discussed. The application of fracture mechanics to damage tolerance and fracture control is discussed. Several example problems and a practice set of problems are given.

  19. Elastic scattering in geometrical model

    NASA Astrophysics Data System (ADS)

    Plebaniak, Zbigniew; Wibig, Tadeusz

    2016-10-01

    The experimental data on proton-proton elastic and inelastic scattering emerging from the measurements at the Large Hadron Collider, calls for an efficient model to fit the data. We have examined the optical, geometrical picture and we have found the simplest, linear dependence of this model parameters on the logarithm of the interaction energy with the significant change of the respective slopes at one point corresponding to the energy of about 300 GeV. The logarithmic dependence observed at high energies allows one to extrapolate the proton-proton elastic, total (and inelastic) cross sections to ultra high energies seen in cosmic rays events which makes a solid justification of the extrapolation to very high energy domain of cosmic rays and could help us to interpret the data from an astrophysical and a high energy physics point of view.

  20. Elastic modulus of viral nanotubes

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Ge, Zhibin; Fang, Jiyu

    2008-09-01

    We report an experimental and theoretical study of the radial elasticity of tobacco mosaic virus (TMV) nanotubes. An atomic force microscope tip is used to apply small radial indentations to deform TMV nanotubes. The initial elastic response of TMV nanotubes can be described by finite-element analysis in 5nm indentation depths and Hertz theory in 1.5nm indentation depths. The derived radial Young’s modulus of TMV nanotubes is 0.92±0.15GPa from finite-element analysis and 1.0±0.2GPa from the Hertz model, which are comparable with the reported axial Young’s modulus of 1.1GPa [Falvo , Biophys. J. 72, 1396 (1997)].

  1. Elastic cone for Chinese calligraphy

    NASA Astrophysics Data System (ADS)

    Cai, Fenglei; Li, Haisheng

    2014-01-01

    The brush plays an important role in creating Chinese calligraphy. We regard a single bristle of a writing brush as an elastic rod and the brush tuft absorbing ink as an elastic cone, which naturally deforms according to the force exerted on it when painting on a paper, and the brush footprint is formed by the intersection region between the deformed tuft and the paper plane. To efficiently generate brush strokes, this paper introduces interpolation and texture mapping approach between two adjacent footprints, and automatically applies bristle-splitting texture to the stroke after long-time painting. Experimental results demonstrate that our method is effective and reliable. Users can create realistic calligraphy in real time.

  2. Improved Indentation Test for Measuring Nonlinear Elasticity

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.

    2004-01-01

    A cylindrical-punch indentation technique has been developed as a means of measuring the nonlinear elastic responses of materials -- more specifically, for measuring the moduli of elasticity of materials in cases in which these moduli vary with applied loads. This technique offers no advantage for characterizing materials that exhibit purely linear elastic responses (constant moduli of elasticity, independent of applied loads). However, the technique offers a significant advantage for characterizing such important materials as plasma-sprayed thermal-barrier coatings, which, in cyclic loading, exhibit nonlinear elasticity with hysteresis related to compaction and sliding within their microstructures.

  3. Nuclear rainbow in elastic scattering of {sup 9}Be nuclei

    SciTech Connect

    Glukhov, Yu. A. Ogloblin, A. A.; Artemov, K. P.; Rudakov, V. P.

    2010-01-15

    A systematic investigation of the elastic scattering of the {sup 9}Be nucleus, which is among themost loosely bound stable nuclei was performed.Differential cross sections for elastic {sup 9}Be + {sup 16}O scattering were measured at a c.m. energy of 47.5 MeV (beam of 132-MeV {sup 16}O nuclei). Available data at different energy values and data for neighboring nuclei were included in our analysis. As a result, the very fact of rainbow scattering was reliably established for the first time in systems involving {sup 9}Be. In addition, the analysis in question made it possible to identify Airy minima and to determine unambiguously the nucleus-nucleus potential with a high probability.

  4. Elastic properties of epithelial cells probed by atomic force microscopy.

    PubMed

    Brückner, Bastian R; Janshoff, Andreas

    2015-11-01

    Cellular mechanics plays a crucial role in many biological processes such as cell migration, cell growth, embryogenesis, and oncogenesis. Epithelia respond to environmental cues comprising biochemical and physical stimuli through defined changes in cell elasticity. For instance, cells can differentiate between certain properties such as viscoelasticity or topography of substrates by adapting their own elasticity and shape. A living cell is a complex viscoelastic body that not only exhibits a shell architecture composed of a membrane attached to a cytoskeleton cortex but also generates contractile forces through its actomyosin network. Here we review cellular mechanics of single cells in the context of epithelial cell layers responding to chemical and physical stimuli. This article is part of a Special Issue entitled: Mechanobiology. PMID:26193077

  5. Structural mechanics and helical geometry of thin elastic composites.

    PubMed

    Wada, Hirofumi

    2016-09-21

    Helices are ubiquitous in nature, and helical shape transition is often observed in residually stressed bodies, such as composites, wherein materials with different mechanical properties are glued firmly together to form a whole body. Inspired by a variety of biological examples, the basic physical mechanism responsible for the emergence of twisting and bending in such thin composite structures has been extensively studied. Here, we propose a simplified analytical model wherein a slender membrane tube undergoes a helical transition driven by the contraction of an elastic ribbon bound to the membrane surface. We analytically predict the curvature and twist of an emergent helix as functions of differential strains and elastic moduli, which are confirmed by our numerical simulations. Our results may help understand shapes observed in different biological systems, such as spiral bacteria, and could be applied to novel designs of soft machines and robots.

  6. Structural mechanics and helical geometry of thin elastic composites.

    PubMed

    Wada, Hirofumi

    2016-09-21

    Helices are ubiquitous in nature, and helical shape transition is often observed in residually stressed bodies, such as composites, wherein materials with different mechanical properties are glued firmly together to form a whole body. Inspired by a variety of biological examples, the basic physical mechanism responsible for the emergence of twisting and bending in such thin composite structures has been extensively studied. Here, we propose a simplified analytical model wherein a slender membrane tube undergoes a helical transition driven by the contraction of an elastic ribbon bound to the membrane surface. We analytically predict the curvature and twist of an emergent helix as functions of differential strains and elastic moduli, which are confirmed by our numerical simulations. Our results may help understand shapes observed in different biological systems, such as spiral bacteria, and could be applied to novel designs of soft machines and robots. PMID:27510457

  7. Elastic fibres in health and disease.

    PubMed

    Kielty, Cay M

    2006-08-08

    Elastic fibres are a major class of extracellular matrix fibres that are abundant in dynamic connective tissues such as arteries, lungs, skin and ligaments. Their structural role is to endow tissues with elastic recoil and resilience. They also act as an important adhesion template for cells, and they regulate growth factor availability. Mutations in major structural components of elastic fibres, especially elastin, fibrillins and fibulin-5, cause severe, often life-threatening, heritable connective tissue diseases such as Marfan syndrome, supravalvular aortic stenosis and cutis laxa. Elastic-fibre function is also frequently compromised in damaged or aged elastic tissues. The ability to regenerate or engineer elastic fibres and tissues remains a significant challenge, requiring improved understanding of the molecular and cellular basis of elastic-fibre biology and pathology, and ability to regulate the spatiotemporal expression and assembly of its molecular components.

  8. Elastic fibres in health and disease.

    PubMed

    Baldwin, Andrew K; Simpson, Andreja; Steer, Ruth; Cain, Stuart A; Kielty, Cay M

    2013-08-20

    Elastic fibres are insoluble components of the extracellular matrix of dynamic connective tissues such as skin, arteries, lungs and ligaments. They are laid down during development, and comprise a cross-linked elastin core within a template of fibrillin-based microfibrils. Their function is to endow tissues with the property of elastic recoil, and they also regulate the bioavailability of transforming growth factor β. Severe heritable elastic fibre diseases are caused by mutations in elastic fibre components; for example, mutations in elastin cause supravalvular aortic stenosis and autosomal dominant cutis laxa, mutations in fibrillin-1 cause Marfan syndrome and Weill-Marchesani syndrome, and mutations in fibulins-4 and -5 cause autosomal recessive cutis laxa. Acquired elastic fibre defects include dermal elastosis, whereas inflammatory damage to fibres contributes to pathologies such as pulmonary emphysema and vascular disease. This review outlines the latest understanding of the composition and assembly of elastic fibres, and describes elastic fibre diseases and current therapeutic approaches.

  9. Avalanche dynamics of elastic interfaces.

    PubMed

    Le Doussal, Pierre; Wiese, Kay Jörg

    2013-08-01

    Slowly driven elastic interfaces, such as domain walls in dirty magnets, contact lines wetting a nonhomogeneous substrate, or cracks in brittle disordered material proceed via intermittent motion, called avalanches. Here we develop a field-theoretic treatment to calculate, from first principles, the space-time statistics of instantaneous velocities within an avalanche. For elastic interfaces at (or above) their (internal) upper critical dimension d≥d(uc) (d(uc)=2,4 respectively for long-ranged and short-ranged elasticity) we show that the field theory for the center of mass reduces to the motion of a point particle in a random-force landscape, which is itself a random walk [Alessandro, Beatrice, Bertotti, and Montorsi (ABBM) model]. Furthermore, the full spatial dependence of the velocity correlations is described by the Brownian-force model (BFM) where each point of the interface sees an independent Brownian-force landscape. Both ABBM and BFM can be solved exactly in any dimension d (for monotonous driving) by summing tree graphs, equivalent to solving a (nonlinear) instanton equation. We focus on the limit of slow uniform driving. This tree approximation is the mean-field theory (MFT) for realistic interfaces in short-ranged disorder, up to the renormalization of two parameters at d=d(uc). We calculate a number of observables of direct experimental interest: Both for the center of mass, and for a given Fourier mode q, we obtain various correlations and probability distribution functions (PDF's) of the velocity inside an avalanche, as well as the avalanche shape and its fluctuations (second shape). Within MFT we find that velocity correlations at nonzero q are asymmetric under time reversal. Next we calculate, beyond MFT, i.e., including loop corrections, the one-time PDF of the center-of-mass velocity u[over ·] for dimension d

  10. Young's modulus reconstruction for elasticity imaging of deep venous thrombosis: animal studies

    NASA Astrophysics Data System (ADS)

    Aglyamov, Salavat R.; Xie, Hua; Kim, Kang; Rubin, Jonathan M.; O'Donnell, Matthew; Wakefield, T. W.; Myers, D.; Emelianov, Stanislav Y.

    2004-04-01

    Recently, it was suggested that ultrasound elasticity imaging can be used to age deep vein thrombosis (DVT) since blood clot hardness changes with fibrin content. The main components of ultrasound elasticity imaging are deformation of the object, speckle or internal boundary tracking and evaluation of tissue motion, measurement of strain tensor components, and reconstruction of the spatial distribution of elastic modulus using strain images. In this paper, we investigate a technique for Young's modulus reconstruction to quantify ultrasound elasticity imaging of DVT. In-vivo strain imaging experiments were performed using Sprague-Dawley rats with surgically induced clots in the inferior vena cavas (IVC). In this model, the clot matures from acute to chronic in less than 10 days. Therefore, nearly every 24 hours the strain imaging experiments were performed to reveal temporal transformation of the clot. The measured displacement and strain images were then converted into maps of elasticity using model-based elasticity reconstruction where the blood clot within an occluded vein was approximated as a layered elastic cylinder surrounded by incompressible tissue. Results of this study demonstrate that Young's modulus gradually increases with clot maturity and can be used to differentiate clots providing a desperately needed clinical tool of DVT staging.

  11. Quantum diffraction grating: A possible new description of nuclear elastic scattering

    NASA Astrophysics Data System (ADS)

    Wojciechowski, H.

    2016-02-01

    The problem of discontinuous functions and their representations in the form of Legendre polynomial series in quantum nuclear scattering theory is presented briefly. The problem is quite old yet not adequately explained in numerous Quantum Theory textbooks and sometimes not correctly understood by physicists. Introduction of the generalized functions into the quantum scattering theory clarifies the problem and allows to propose new interpretations of nuclear elastic scattering phenomenon. The derived new forms of the full elastic scattering amplitudes and possibility of splitting them suggest existence of dynamical quantum diffraction grating around the nuclei. Particularly important fact is that this grating existing in the space around the nucleus makes considerable contribution to the experimental elastic differential cross-section. All these might be quite important in analyses of nuclear elastic scattering data and so require to be stated in a more detailed and clear way.

  12. Feynman's Proof and Non-Elastic Displacement Fields: Relationship Between Magnetic Field and Defects Field

    NASA Astrophysics Data System (ADS)

    Nakamura, Nozomu; Yamasaki, Kazuhito

    2016-08-01

    We consider the relationship between the magnetic field and the non-elastic displacement field including defects, from the viewpoints of non-commutativity of the positions and non-commutativity of the derivatives. The former non-commutativity is related to the magnetic field by Feynman's proof (1948), and the latter is related to the defect fields by the continuum theory of defects. We introduce the concept of differential geometry to the non-elastic displacement field and derive an extended relation that includes basic equations, such as Gauss's law for magnetism and the conservation law for dislocation density. The relation derived in this paper also extends the first Bianchi identity in linear approximation to include the effect of magnetism. These findings suggest that Feynman's approach with a non-elastic displacement field is useful for understanding the relationship between magnetism and non-elastic mechanics.

  13. Elasticity Imaging of Polymeric Media

    PubMed Central

    Sridhar, Mallika; Liu, Jie; Insana, Michael F.

    2009-01-01

    Viscoelastic properties of soft tissues and hydropolymers depend on the strength of molecular bonding forces connecting the polymer matrix and surrounding fluids. The basis for diagnostic imaging is that disease processes alter molecular-scale bonding in ways that vary the measurable stiffness and viscosity of the tissues. This paper reviews linear viscoelastic theory as applied to gelatin hydrogels for the purpose of formulating approaches to molecular-scale interpretation of elasticity imaging in soft biological tissues. Comparing measurements acquired under different geometries, we investigate the limitations of viscoelastic parameters acquired under various imaging conditions. Quasistatic (step-and-hold and low-frequency harmonic) stimuli applied to gels during creep and stress relaxation experiments in confined and unconfined geometries reveal continuous, bimodal distributions of respondance times. Within the linear range of responses, gelatin will behave more like a solid or fluid depending on the stimulus magnitude. Gelatin can be described statistically from a few parameters of low-order rheological models that form the basis of viscoelastic imaging. Unbiased estimates of imaging parameters are obtained only if creep data are acquired for greater than twice the highest retardance time constant and any steady-state viscous response has been eliminated. Elastic strain and retardance time images are found to provide the best combination of contrast and signal strength in gelatin. Retardance times indicate average behavior of fast (1–10 s) fluid flows and slow (50–400 s) matrix restructuring in response to the mechanical stimulus. Insofar as gelatin mimics other polymers, such as soft biological tissues, elasticity imaging can provide unique insights into complex structural and biochemical features of connectives tissues affected by disease. PMID:17408331

  14. Equilibrium theory for braided elastic filaments

    NASA Astrophysics Data System (ADS)

    van der Heijden, Gert

    Motivated by supercoiling of DNA and other filamentous structures, we formulate a theory for equilibria of 2-braids, i.e., structures formed by two elastic rods winding around each other in continuous contact and subject to a local interstrand interaction. Unlike in previous work no assumption is made on the shape of the contact curve. Rather, this shape is found as part of the solution. The theory is developed in terms of a moving frame of directors attached to one of the strands with one of the directors pointing to the position of the other strand. The constant-distance constraint is automatically satisfied by the introduction of what we call braid strains. The price we pay is that the potential energy involves arclength derivatives of these strains, thus giving rise to a second-order variational problem. The Euler-Lagrange equations for this problem give balance equations for the overall braid force and moment referred to the moving frame as well as differential equations that can be interpreted as effective constitutive relations encoding the effect that the second strand has on the first as the braid deforms under the action of end loads. Simple analytical cases are discussed first and used as starting solutions in parameter continuation studies to compute classes of both open and closed (linked or knotted) braid solutions.

  15. Elastic mismatch enhances cell motility

    NASA Astrophysics Data System (ADS)

    Bresler, Yony; Palmieri, Benoit; Grant, Martin

    In recent years, the study of physics phenomena in cancer has drawn considerable attention. In cancer metastasis, a soft cancer cell leaves the tumor, and must pass through the endothelium before reaching the bloodstream. Using a phase-field model we have shown that the elasticity mismatch between cells alone is sufficient to enhance the motility of thesofter cancer cell by means of bursty migration, in agreement with experiment. We will present further characterization of these behaviour, as well as new possible applications for this model.

  16. Variable Joint Elasticities in Running

    NASA Astrophysics Data System (ADS)

    Peter, Stephan; Grimmer, Sten; Lipfert, Susanne W.; Seyfarth, Andre

    In this paper we investigate how spring-like leg behavior in human running is represented at joint level. We assume linear torsion springs in the joints and between the knee and the ankle joint. Using experimental data of the leg dynamics we compute how the spring parameters (stiffness and rest angles) change during gait cycle. We found that during contact the joints reveal elasticity with strongly changing parameters and compare the changes of different parameters for different spring arrangements. The results may help to design and improve biologically inspired spring mechanisms with adjustable parameters.

  17. Elastic properties of spherically anisotropic piezoelectric composites

    NASA Astrophysics Data System (ADS)

    Wei, En-Bo; Gu, Guo-Qing; Poon, Ying-Ming

    2010-09-01

    Effective elastic properties of spherically anisotropic piezoelectric composites, whose spherically anisotropic piezoelectric inclusions are embedded in an infinite non-piezoelectric matrix, are theoretically investigated. Analytical solutions for the elastic displacements and the electric potentials under a uniform external strain are derived exactly. Taking into account of the coupling effects of elasticity, permittivity and piezoelectricity, the formula is derived for estimating the effective elastic properties based on the average field theory in the dilute limit. An elastic response mechanism is revealed, in which the effective elastic properties increase as inclusion piezoelectric properties increase and inclusion dielectric properties decrease. Moreover, a piezoelectric response mechanism, of which the effective piezoelectric response vanishes due to the symmetry of spherically anisotropic composite, is also disclosed.

  18. Elastic, Conductive, Polymeric Hydrogels and Sponges

    PubMed Central

    Lu, Yun; He, Weina; Cao, Tai; Guo, Haitao; Zhang, Yongyi; Li, Qingwen; Shao, Ziqiang; Cui, Yulin; Zhang, Xuetong

    2014-01-01

    As a result of inherent rigidity of the conjugated macromolecular chains resulted from the delocalized π-electron system along the polymer backbone, it has been a huge challenge to make conducting polymer hydrogels elastic by far. Herein elastic and conductive polypyrrole hydrogels with only conducting polymer as the continuous phase have been simply synthesized in the indispensable conditions of 1) mixed solvent, 2) deficient oxidant, and 3) monthly secondary growth. The elastic mechanism and oxidative polymerization mechanism on the resulting PPy hydrogels have been discussed. The resulting hydrogels show some novel properties, e.g., shape memory elasticity, fast functionalization with various guest objects, and fast removal of organic infectants from aqueous solutions, all of which cannot be observed from traditional non-elastic conducting polymer counterparts. What's more, light-weight, elastic, and conductive organic sponges with excellent stress-sensing behavior have been successfully achieved via using the resulting polypyrrole hydrogels as precursors. PMID:25052015

  19. Hummingbird tongues are elastic micropumps

    PubMed Central

    Rico-Guevara, Alejandro; Fan, Tai-Hsi; Rubega, Margaret A.

    2015-01-01

    Pumping is a vital natural process, imitated by humans for thousands of years. We demonstrate that a hitherto undocumented mechanism of fluid transport pumps nectar onto the hummingbird tongue. Using high-speed cameras, we filmed the tongue–fluid interaction in 18 hummingbird species, from seven of the nine main hummingbird clades. During the offloading of the nectar inside the bill, hummingbirds compress their tongues upon extrusion; the compressed tongue remains flattened until it contacts the nectar. After contact with the nectar surface, the tongue reshapes filling entirely with nectar; we did not observe the formation of menisci required for the operation of capillarity during this process. We show that the tongue works as an elastic micropump; fluid at the tip is driven into the tongue's grooves by forces resulting from re-expansion of a collapsed section. This work falsifies the long-standing idea that capillarity is an important force filling hummingbird tongue grooves during nectar feeding. The expansive filling mechanism we report in this paper recruits elastic recovery properties of the groove walls to load nectar into the tongue an order of magnitude faster than capillarity could. Such fast filling allows hummingbirds to extract nectar at higher rates than predicted by capillarity-based foraging models, in agreement with their fast licking rates. PMID:26290074

  20. Hummingbird tongues are elastic micropumps.

    PubMed

    Rico-Guevara, Alejandro; Fan, Tai-Hsi; Rubega, Margaret A

    2015-08-22

    Pumping is a vital natural process, imitated by humans for thousands of years. We demonstrate that a hitherto undocumented mechanism of fluid transport pumps nectar onto the hummingbird tongue. Using high-speed cameras, we filmed the tongue-fluid interaction in 18 hummingbird species, from seven of the nine main hummingbird clades. During the offloading of the nectar inside the bill, hummingbirds compress their tongues upon extrusion; the compressed tongue remains flattened until it contacts the nectar. After contact with the nectar surface, the tongue reshapes filling entirely with nectar; we did not observe the formation of menisci required for the operation of capillarity during this process. We show that the tongue works as an elastic micropump; fluid at the tip is driven into the tongue's grooves by forces resulting from re-expansion of a collapsed section. This work falsifies the long-standing idea that capillarity is an important force filling hummingbird tongue grooves during nectar feeding. The expansive filling mechanism we report in this paper recruits elastic recovery properties of the groove walls to load nectar into the tongue an order of magnitude faster than capillarity could. Such fast filling allows hummingbirds to extract nectar at higher rates than predicted by capillarity-based foraging models, in agreement with their fast licking rates. PMID:26290074