Creation and dynamical co-evolution of electron and ion channel transport barriers

International Nuclear Information System (INIS)

Newman, D.E.

2002-01-01

A wide variety of magnetic confinement devices have found transitions to an enhanced confinement regime. Simple dynamical models have been able to capture much of the dynamics of these barriers however an open question has been the disconnected nature of the electron thermal transport channel sometimes observed in the presence of a standard ('ion channel' barrier. By adding to simple barrier model an evolution equation for electron fluctuations we can investigate the interaction between the formation of the standard ion channel barrier and the somewhat less common electron channel barrier. Barrier formation in the electron channel is even more sensitive to the alignment of the various gradients making up the sheared radial electric field than the ion barrier is. Electron channel heat transport is found to significantly increase after the formation of the ion channel barrier but before the electron channel barrier is formed. This increased transport is important in the barrier evolution. (author)

Production, transport and charge capture measurements of highly charged recoil ions

International Nuclear Information System (INIS)

Trebus, U.E.

1989-01-01

An experiment is described to study highly charged recoil ions on-line to the heavy accelerator UNILAC at GSI. The highly charged recoil ions are produced by heavy-ion bombardment of a gas target. Subsequently the slow highly charged recoil ions are extracted from the ionization volume, and guided through a beam transport line to a Wien filter for charge state selection and to a collision region to study charge transfer processes. Several experiments were carried out to show the efficient charge state separation. Charge states up to q = 15 were observed. When using a retarding field analyzer cross sections for single electron capture were determined for different charge states of Xe q+ for q = 4 to 11 and He gas. The experiments demonstrated increasing charge transfer cross sections with increasing charge state q and indicated the effect of near resonant charge capture for q = 6. The flexible data acquisition system used, is described and other future experiments, such as for instance in flight ion-trapping are indicated in the appendix

Ion-Molecule Reaction Dynamics.

Science.gov (United States)

Meyer, Jennifer; Wester, Roland

2017-05-05

We review the recent advances in the investigation of the dynamics of ion-molecule reactions. During the past decade, the combination of single-collision experiments in crossed ion and neutral beams with the velocity map ion imaging detection technique has enabled a wealth of studies on ion-molecule reactions. These methods, in combination with chemical dynamics simulations, have uncovered new and unexpected reaction mechanisms, such as the roundabout mechanism and the subtle influence of the leaving group in anion-molecule nucleophilic substitution reactions. For this important class of reactions, as well as for many fundamental cation-molecule reactions, the information obtained with crossed-beam imaging is discussed. The first steps toward understanding micro-solvation of ion-molecule reaction dynamics are presented. We conclude with the presentation of several interesting directions for future research.

Theory of nuclear excitation by electron capture for heavy ions

Energy Technology Data Exchange (ETDEWEB)

Gagyi-Palffy, A.

2006-07-01

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

Electron capture to autoionizing states of multiply charged ions

International Nuclear Information System (INIS)

Mack, E.M.

1987-01-01

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

Dynamics and control of robot for capturing objects in space

Science.gov (United States)

Huang, Panfeng

Space robots are expected to perform intricate tasks in future space services, such as satellite maintenance, refueling, and replacing the orbital replacement unit (ORU). To realize these missions, the capturing operation may not be avoided. Such operations will encounter some challenges because space robots have some unique characteristics unfound on ground-based robots, such as, dynamic singularities, dynamic coupling between manipulator and space base, limited energy supply and working without a fixed base, and so on. In addition, since contacts and impacts may not be avoided during capturing operation. Therefore, dynamics and control problems of space robot for capturing objects are significant research topics if the robots are to be deployed for the space services. A typical servicing operation mainly includes three phases: capturing the object, berthing and docking the object, then repairing the target. Therefore, this thesis will focus on resolving some challenging problems during capturing the object, berthing and docking, and so on. In this thesis, I study and analyze the dynamics and control problems of space robot for capturing objects. This work has potential impact in space robotic applications. I first study the contact and impact dynamics of space robot and objects. I specifically focus on analyzing the impact dynamics and mapping the relationship of influence and speed. Then, I develop the fundamental theory for planning the minimum-collision based trajectory of space robot and designing the configuration of space robot at the moment of capture. To compensate for the attitude of the space base during the capturing approach operation, a new balance control concept which can effectively balance the attitude of the space base using the dynamic couplings is developed. The developed balance control concept helps to understand of the nature of space dynamic coupling, and can be readily applied to compensate or minimize the disturbance to the space base

Electron capture by fast protons from helium-like ions

International Nuclear Information System (INIS)

Samanta, R.; Purkait, M.

2011-01-01

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

Electron capture by multicharged ions at eV energies

International Nuclear Information System (INIS)

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

1988-01-01

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

Recent progress in nonperturbative electromagnetic lepton-pair production with capture in relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Wells, J.C.; Oberacker, V.E.; Umar, A.S.

1993-01-01

The prospect of new colliding-beam accelerators capable of producing collisions of highly stripped high-Z ions, at fixed-target energies per nucleon up to 20 TeV or more, has motivated much interest in lepton-pair production from the QED vacuum. The time-dependent and essentially classical electromagnetic fields involved in such collisions contain larger Fourier components which give rise to sizable lepton-pair production in addition to many other exotic particles. The process of electron-positron production with electron capture is a principal beam-loss mechanism for highly charged ions in a storage ring. In this process, the electron is created in a bound state of one of the participant heavy ions (most likely the 1s state), thus changing the ion's charge state and causing it to be deflected out of the beam. There is a long and sometimes controversial history concerning the use of perturbative methods in studying electromagnetic lepton-pair production; however, reliable perturbative calculations have been used as input into design models for the Relativistic Heavy-Ion Collider (RHIC). Applying perturbation theory to these processes at high energies and small impact parameters results in probabilities which violate unitarity, and cross sections which violate the Froissart bound. This evidence, along with the initial nonperturbative studies, suggests that higher-order QED effects will be important for extreme relativistic collisions. Clearly, large nonperturbative effects in electron-pair production with capture would have important implications for RHIC. In this paper, the authors briefly discuss recent progress in nonperturbative studies of the capture problem. In Section 2, they state the Dirac equation for a lepton in the time-dependent external field of a heavy ion which must be solved to compute lepton-capture probabilities. Section 4 surveys results from recent applications of coupled-channel and lattice techniques to the lepton-capture problem

Multiple electron capture in close ion-atom collisions

International Nuclear Information System (INIS)

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

1989-01-01

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

The ion capturing effect of 5° SiOx alignment films in liquid crystal devices

Science.gov (United States)

Huang, Yi; Bos, Philip J.; Bhowmik, Achintya

2010-09-01

We show that SiOx, deposited at 5° to the interior surface of a liquid crystal cell allows for a surprisingly substantial reduction in the ion concentration of liquid crystal devices. We have investigated this effect and found that this type of film, due to its surface morphology, captures ions from the liquid crystal material. Ion adsorption on 5° SiOx film obeys the Langmuir isotherm. Experimental results shown allow estimation of the ion capturing capacity of these films to be more than an order of 10 000/μm2. These types of materials are useful for new types of very low power liquid crystal devices such as e-books.

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

International Nuclear Information System (INIS)

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

1981-01-01

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

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

International Nuclear Information System (INIS)

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

2004-01-01

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

Electron capture by Ne3+ ions from atomic hydrogen

International Nuclear Information System (INIS)

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

2004-01-01

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

Electron capture by Ne3+ ions from atomic hydrogen

Science.gov (United States)

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

2004-05-01

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

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

International Nuclear Information System (INIS)

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

1986-01-01

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

Dynamics in ion-molecule collisions at high velocities: One- and two-electron processes

International Nuclear Information System (INIS)

Wang, Yudong.

1992-01-01

This dissertation addresses the dynamic interactions in ion-molecule collisions. Theoretical methods are developed for single and multiple electron transitions in fast collisions with diatomic molecules by heavy-ion projectiles. Various theories and models are developed to treat the three basic inelastic processes (excitation, ionization and charge transfer) involving one and more electrons. The development, incorporating the understanding of ion-atom collision theories with some unique characteristics for molecular targets, provides new insights into phenomena that are absent from collisions with atomic targets. The influence from the multiple scattering centers on collision dynamics is assessed. For diatomic molecules, effects due to a fixed molecular orientation or alignment are calculated and compared with available experimental observations. Compared with excitation and ionization, electron capture, which probes deeper into the target, presents significant two-center interference and strong orientation dependence. Attention has been given in this dissertation to exploring mechanisms for two-and multiple electron transitions. Application of independent electron approximation to transfer excitation from molecular hydrogen is studied. Electron-electron interaction originated from projectile and target nuclear centers is studied in conjunction with the molecular nature of target. Limitations of the present theories and models as well as possible new areas for future theoretical and experimental applications are also discussed. This is the first attempt to describe multi-electron processes in molecular dynamics involving fast highly charged ions

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

Energy Technology Data Exchange (ETDEWEB)

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

1986-01-01

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

Recoil separators for radiative capture using radioactive ion beams. Recent advances and detection techniques

Energy Technology Data Exchange (ETDEWEB)

Ruiz, Chris [TRIUMF, Vancouver, BC (Canada); Greife, Uwe; Hager, Ulrike [Colorado School of Mines, Golden, CO (United States)

2014-06-15

Radiative capture reactions involving the fusion of hydrogen or helium are ubiquitous in the stellar history of the universe, and are some of the most important reactions in the processes that govern nucleosynthesis and energy generation in both static and explosive scenarios. However, radiative capture reactions pose some of the most difficult experimental challenges due to extremely small cross sections. With the advent of recoil separators and techniques in inverse kinematics, it is now possible to measure radiative capture reactions on very short-lived radioactive nuclei, and in the presence of high experimental backgrounds. In this paper we review the experimental needs for making measurements of astrophysical importance on radiative capture reactions. We also review some of the important historical advances in the field of recoil separators as well as describe current techniques and performance milestones, including descriptions of some of the separators most recently working at radioactive ion beam facilities, such as DRAGON at TRIUMF and the DRS at the Holifield Radioactive Ion Beam Facility. We will also summarize some of the scientific highlight measurements at the RIB facilities. (orig.)

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

International Nuclear Information System (INIS)

Gilbody, H B; McCullough, R W

2004-01-01

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

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

International Nuclear Information System (INIS)

Jung, Young-Dae; Kato, Daiji

2009-05-01

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

Electron capture in ion-molecule collisions at intermediate energy

International Nuclear Information System (INIS)

Kumura, M.

1986-01-01

Recent progress of theoretical charge transfer study in ion-molecule collisions at the intermediate energy is reviewed. Concept of close and distant collisions obtained from extensive ion-atom collision studies is identified so that it can be utilized to model two distinct collision processes. For a close collision, explicit representation of the whole collision complex is necessary to describe collision dynamics correctly, while a model potential approach for molecule is appropriate for a distant collision. It is shown that these two distinct models are indeed capable of reproducing experimental charge transfer cross sections. Some remarks for further theoretical study of ion-molecule collisions are also given. 21 refs., 8 figs

Electron capture by multicharged ions from hydrogen atoms at eV energies

International Nuclear Information System (INIS)

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

1990-01-01

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

77 FR 19408 - Dynamic Mobility Applications and Data Capture Management Programs; Notice of Public Meeting

Science.gov (United States)

2012-03-30

... DEPARTMENT OF TRANSPORTATION Dynamic Mobility Applications and Data Capture Management Programs... stakeholders an update on the Data Capture and Management (DCM) and Dynamic Mobility Applications (DMA... critical issues designed to garner stakeholder feedback. About the Dynamic Mobility Application and Data...

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

International Nuclear Information System (INIS)

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

2000-11-01

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

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

Science.gov (United States)

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

2003-03-07

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

Ion Dynamics at Shocks: Ion Reflection and Beam Formation at Quasi-perpendicular Shocks

International Nuclear Information System (INIS)

Kucharek, Harald; Moebius, Eberhard

2005-01-01

The physics of collisionless shocks is controlled by the ion dynamics. The generation of gyrating ions by reflection as well as the formation of field-aligned ion beams are essential parts of this dynamic. On the one hand reflection is most likely the first interaction of ions with the shock before they undergo the downstream thermalization process. On the other hand field-aligned ion beams, predominately found at the quasi-perpendicular bow shock, propagate into the distant foreshock region and may create wave activity. We revisit ion reflection, the source and basic production mechanism of field-aligned ion beams, by using multi-spacecraft measurements and contrast these observations with existing theories. Finally, we propose an alternative production mechanism

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

International Nuclear Information System (INIS)

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

1992-03-01

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

Dynamic Operation and Simulation of Post-Combustion CO2 Capture

DEFF Research Database (Denmark)

Gaspar, Jozsef; Gladis, Arne; Jørgensen, John Bagterp

2016-01-01

Thermal power need to operate, on a daily basis, with frequent and fast load changes to balance the large variations of intermittent energy sources, such as wind and solar energy. To make the integration of carbon capture to power plants economically and technically feasible, the carbon capture...... process has to be able to follow these fast and large load changes without decreasing the overall performance of the carbon capture plant. Therefore, dynamic models for simulation, optimization and control system design are essential. In this work, we compare the transient behavior of the model against...

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

NARCIS (Netherlands)

POSTHUMUS, JH; MORGENSTERN, R

1992-01-01

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

Influence of capture to excited states of multiply charged ion beams colliding with small molecules

International Nuclear Information System (INIS)

Montenegro, P; Monti, J M; Fojón, O A; Hanssen, J; Rivarola, R D

2015-01-01

Electron capture by multiply charged ions impacting on small molecules is theoretically investigated. Particular attention is paid to the case of biological targets. The interest is focused on the importance of the transition to excited final states which can play a dominant role on the total capture cross sections. Projectiles at intermediate and high collision energies are considered. Comparison with existing experimental data is shown. (paper)

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

International Nuclear Information System (INIS)

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

1991-01-01

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

Structure and dynamics of aqueous solution of uranyl ions

International Nuclear Information System (INIS)

Chopra, Manish; Choudhury, Niharendu

2014-01-01

The present work describes a molecular dynamics simulation study of structure and dynamics of aqueous solution of uranyl ions in water. Structural properties of the system in terms of radial distribution functions and dynamical characteristics as obtained through velocity autocorrelation function and mean square displacements have been analyzed. The results for radial distribution functions show the oxygen of water to form the first solvation shell at 2.4 Å around the uranium atom, whereas the hydrogen atoms of water are distributed around the uranium atom with the major peak at around 3.0 Å. Analyses of transport behaviors of ions and water through MSD indicates that the diffusion of the uranyl ion is much less as compared to that of the water molecules. It is also observed that the dynamical behavior of water molecules gets modified due to the presence of uranyl ion. The effect of increase in concentration of uranyl ions on the structure and dynamics of water molecules is also studied

Dynamic electrochemical measurement of chloride ions

NARCIS (Netherlands)

Abbas, Yawar; de Graaf, Derk B.; Olthuis, Wouter; van den Berg, Albert

2016-01-01

This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver chloride electrode is used extensively for potentiometric measurement of chloride ions concentration in electrolyte. In this measurement,

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

International Nuclear Information System (INIS)

Wang Fei; Gou Bingcong

2008-01-01

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

Prototype Development: Context-Driven Dynamic XML Ophthalmologic Data Capture Application

Science.gov (United States)

Schwei, Kelsey M; Kadolph, Christopher; Finamore, Joseph; Cancel, Efrain; McCarty, Catherine A; Okorie, Asha; Thomas, Kate L; Allen Pacheco, Jennifer; Pathak, Jyotishman; Ellis, Stephen B; Denny, Joshua C; Rasmussen, Luke V; Tromp, Gerard; Williams, Marc S; Vrabec, Tamara R; Brilliant, Murray H

2017-01-01

Background The capture and integration of structured ophthalmologic data into electronic health records (EHRs) has historically been a challenge. However, the importance of this activity for patient care and research is critical. Objective The purpose of this study was to develop a prototype of a context-driven dynamic extensible markup language (XML) ophthalmologic data capture application for research and clinical care that could be easily integrated into an EHR system. Methods Stakeholders in the medical, research, and informatics fields were interviewed and surveyed to determine data and system requirements for ophthalmologic data capture. On the basis of these requirements, an ophthalmology data capture application was developed to collect and store discrete data elements with important graphical information. Results The context-driven data entry application supports several features, including ink-over drawing capability for documenting eye abnormalities, context-based Web controls that guide data entry based on preestablished dependencies, and an adaptable database or XML schema that stores Web form specifications and allows for immediate changes in form layout or content. The application utilizes Web services to enable data integration with a variety of EHRs for retrieval and storage of patient data. Conclusions This paper describes the development process used to create a context-driven dynamic XML data capture application for optometry and ophthalmology. The list of ophthalmologic data elements identified as important for care and research can be used as a baseline list for future ophthalmologic data collection activities. PMID:28903894

Quench dynamics of two coupled zig-zag ion chains

Energy Technology Data Exchange (ETDEWEB)

Klumpp, Andrea, E-mail: andrea.klumpp@physnet.uni-hamburg.de [Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Liebchen, Benno [SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD (United Kingdom); Schmelcher, Peter [Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg (Germany)

2016-08-06

We explore the non-equilibrium dynamics of two coupled zig-zag chains of trapped ions in a double well potential. Following a quench of the potential barrier between both wells, the induced coupling between both chains due to the long-range interaction of the ions leads to the complete loss of order in the radial direction. The resulting dynamics is however not exclusively irregular but leads to phases of motion during which various ordered structures appear with ions arranged in arcs, lines and crosses. We quantify the emerging order by introducing a suitable measure and complement our analysis of the ion dynamics using a normal mode analysis showing a decisive population transfer between only a few distinguished modes. - Highlights: • Novel dynamical phenomenology of two coupled zig-zag ion chains following a trap quench is explored. • Transient ordered ion configurations are unraveled in non-equilibrium dynamics dominated by irregular behavior. • A measure for the diagnosis of this transient order is introduced and applied. • Energy transfer between a few eigen modes is identified as the key mechanism for the occurrence of the ordered configurations.

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

International Nuclear Information System (INIS)

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

1985-01-01

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

Radiative double electron capture in fast heavy ion-atom collisions

International Nuclear Information System (INIS)

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

1996-01-01

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

Dynamics of fragment capture for cluster structures of weakly bound 7Li

Directory of Open Access Journals (Sweden)

Shrivastava A.

2013-12-01

Full Text Available Role of cluster structures of 7Li on reaction dynamics have been studied by performing exclusive measurements of prompt-γ rays from residues with scattered particles at energy, E/Vb = 1.6, with 198Pt target. Yields of the residues resulting after capture of t and 4,5,6He, corresponding to different excitation energies of the composite system were estimated. The results were compared with three body classical-dynamical model for breakup fusion, constrained by the measured fusion, α and t capture cross-sections. The cross-section of residues from capture of α and t agreed well with the prediction of the model showing dominance of the two step process - breakup fusion, while those from tightly bound 6He showed massive transfer to be the dominant mechanism.

Capture of impurity atoms by defects and the distribution of the complexes under ion bormbardment of growing films

International Nuclear Information System (INIS)

Radzhabov, T.D.; Iskanderova, Z.A.; Arutyunova, E.O.; Samigulin, K.R.

1982-01-01

Theoretical study of capture of impurity gas atoms with defects during ion introduction of the impurity in the process of film growth with simultaneous diffusion has been carried out. Concentration profiles of forned impurity-defect complexes have been calculated analytically and numerically by means of a computer in film depth and in a substrate; basic peculiarities of impurity component formation captured with defects in a wide range of changing basic experimental parameters have been revealed. Effect of impurity capture with defects on amount and distribution of total concentration of impurity atoms and intensity of complete absorption of bombarding ions in films have been analyzed. Shown is a possibility for producing films with a high concentration level and almost uniform distribution of the impurity-defect complexes for real, achievable an experiment, values of process parameters as well as a possibility for increasing complete absorption of gaseous impurity wiht concentration growth of capture defects-traps

Hydration and Ion Pairing in Aqueous Mg2+ and Zn2+ Solutions: Force-Field Description Aided by Neutron Scattering Experiments and Ab Initio Molecular Dynamics Simulations.

Science.gov (United States)

Duboué-Dijon, Elise; Mason, Philip E; Fischer, Henry E; Jungwirth, Pavel

2018-04-05

Magnesium and zinc dications possess the same charge and have an almost identical size, yet they behave very differently in aqueous solutions and play distinct biological roles. It is thus crucial to identify the origins of such different behaviors and to assess to what extent they can be captured by force-field molecular dynamics simulations. In this work, we combine neutron scattering experiments in a specific mixture of H 2 O and D 2 O (the so-called null water) with ab initio molecular dynamics simulations to probe the difference in the hydration structure and ion-pairing properties of chloride solutions of the two cations. The obtained data are used as a benchmark to develop a scaled-charge force field for Mg 2+ that includes electronic polarization in a mean field way. We show that using this electronic continuum correction we can describe aqueous magnesium chloride solutions well. However, in aqueous zinc chloride specific interaction terms between the ions need to be introduced to capture ion pairing quantitatively.

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

International Nuclear Information System (INIS)

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

1978-01-01

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

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Molecular ions, Rydberg spectroscopy and dynamics

International Nuclear Information System (INIS)

Jungen, Ch.

2015-01-01

Ion spectroscopy, Rydberg spectroscopy and molecular dynamics are closely related subjects. Multichannel quantum defect theory is a theoretical approach which draws on this close relationship and thereby becomes a powerful tool for the study of systems consisting of a positively charged molecular ion core interacting with an electron which may be loosely bound or freely scattering

Molecular ions, Rydberg spectroscopy and dynamics

Energy Technology Data Exchange (ETDEWEB)

Jungen, Ch. [Laboratoire Aimé Cotton, Université de Paris-Sud, 91405 Orsay (France)

2015-01-22

Ion spectroscopy, Rydberg spectroscopy and molecular dynamics are closely related subjects. Multichannel quantum defect theory is a theoretical approach which draws on this close relationship and thereby becomes a powerful tool for the study of systems consisting of a positively charged molecular ion core interacting with an electron which may be loosely bound or freely scattering.

Dynamical calculations of nuclear fission and heavy-ion reactions

International Nuclear Information System (INIS)

Nix, J.R.; Sierk, A.J.

1984-01-01

With the goal of determining the magnitude and mechanism of nuclear dissipation from comparisons of predictions with experimental data, we describe recent calculations in a unified macroscopic-microscopic approach to large-amplitude collective nuclear motion such as occurs in fission and heavy-ion reactions. We describe the time dependence of the distribution function in phase space of collective coordinates and momenta by a generalized Fokker-Planck equation. The nuclear potential energy of deformation is calculated as the sum of repulsive Coulomb and centrifugal energies and an attractive Yukawa-plus-exponential potential, the inertia tensor is calculated for a superposition of rigid-body rotation and incompressible, nearly irrotational flow by use of the Werner-Wheeler method, and the dissipation ensor that describes the conversion of collective energy into single-particle excitation energy is calculated for two prototype mechanisms that represent opposite extremes of large and small dissipation. We solve the generalized Hamilton equations of motion for the first moments of the distribution function to obtain the mean translational fission-fragment kinetic energy and mass of a third fragment that sometimes forms between the two end fragments, as well as dynamical thresholds, capture cross sections, and ternary events in heavy-ion reactions. 33 references

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

International Nuclear Information System (INIS)

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

1997-01-01

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

On some problems of the dynamics of protons captured by geomagnetic fields

International Nuclear Information System (INIS)

Kudela, K.; Dubinski, Yu.

1977-01-01

Problems on the dynamics of protons captured by the geomagnetic field is reviewed using new experimental data obtained from artificial satellites. The problems on radial and pitch-angular diffusion of high-energy protons on different L-shells are considered. A good agreement is shown to exist between experimental data and diffusion analysis results. The experimental researches of the changes in the fluxes of quasi-captured, captured, and spilled protons are interpreted as a result of the scattering of protons on lowfrequency waves in the magnetosphere. Presented are the graphs of measurement of the flux of spilled and quasi-ca.ptured protons on different L-shells according to the data obtained from the ''ESRO-1A'' and ''Intercosmos-5'' satellites. To clarify the dynamics of the interaction of protons with waves, it is acknowledged as necessary to pay attention to enhancing the role played by a complex character of experiments

From Brownian Dynamics to Markov Chain: An Ion Channel Example

KAUST Repository

Chen, Wan

2014-02-27

A discrete rate theory for multi-ion channels is presented, in which the continuous dynamics of ion diffusion is reduced to transitions between Markovian discrete states. In an open channel, the ion permeation process involves three types of events: an ion entering the channel, an ion escaping from the channel, or an ion hopping between different energy minima in the channel. The continuous dynamics leads to a hierarchy of Fokker-Planck equations, indexed by channel occupancy. From these the mean escape times and splitting probabilities (denoting from which side an ion has escaped) can be calculated. By equating these with the corresponding expressions from the Markov model, one can determine the Markovian transition rates. The theory is illustrated with a two-ion one-well channel. The stationary probability of states is compared with that from both Brownian dynamics simulation and the hierarchical Fokker-Planck equations. The conductivity of the channel is also studied, and the optimal geometry maximizing ion flux is computed. © 2014 Society for Industrial and Applied Mathematics.

Ion-ion dynamic structure factor, acoustic modes, and equation of state of two-temperature warm dense aluminum

Science.gov (United States)

Harbour, L.; Förster, G. D.; Dharma-wardana, M. W. C.; Lewis, Laurent J.

2018-04-01

The ion-ion dynamical structure factor and the equation of state of warm dense aluminum in a two-temperature quasiequilibrium state, with the electron temperature higher than the ion temperature, are investigated using molecular-dynamics simulations based on ion-ion pair potentials constructed from a neutral pseudoatom model. Such pair potentials based on density functional theory are parameter-free and depend directly on the electron temperature and indirectly on the ion temperature, enabling efficient computation of two-temperature properties. Comparison with ab initio simulations and with other average-atom calculations for equilibrium aluminum shows good agreement, justifying a study of quasiequilibrium situations. Analyzing the van Hove function, we find that ion-ion correlations vanish in a time significantly smaller than the electron-ion relaxation time so that dynamical properties have a physical meaning for the quasiequilibrium state. A significant increase in the speed of sound is predicted from the modification of the dispersion relation of the ion acoustic mode as the electron temperature is increased. The two-temperature equation of state including the free energy, internal energy, and pressure is also presented.

Capture of ions by vortex lines in pure 4He and 3He--4He solutions

International Nuclear Information System (INIS)

Ostermeier, R.M.; Glaberson, W.I.

1975-01-01

Measurements of the capture cross section for the negative ion by vortex lines in pure 4 He and a 0.94 percent solution of 3 He in 4 He are presented. A measurable capture of positive ions was not observed in either system. In pure 4 He the departure of the experimental data from the predictions of stochastic theory at lower temperatures is explained in terms of a simple breakdown in that theory, and lifetime effects are shown to be of only secondary importance. The decrease in cross section with decreasing temperature, due essentially to a reduced number density of rotons, is predicted by the results of a Monte Carlo calculation. The cross section in the solution follows stochastic theory to significantly lower temperatures, but at about 1 K there again occurs a marked discrepancy. Measurements of the ion trapping lifetime at low temperatures indicate that it is the finite lifetime that accounts for this discrepancy. Elimination of lifetime effects results in fair agreement between the cross section data in the solution and the predictions of stochastic theory. (11 figures) (auth)

Dynamical limitations to heavy ion fusion

International Nuclear Information System (INIS)

Back, B.B.

1983-01-01

Dynamical limitations to heavy ion fusion reaction are considered. The experimental signatures and the importance of a quasi-fission process are examined. The anaular distributions of fission fragments for the 32 S+ 208 Pb and 16 O+ 238 U systems are presented. It is shown that the observations of quasi-fission for even rather ''light'' heavy ions poeess severe limitations on the fusion process. This result may consequently be responsible for the lack of success of the search for super heavy elements in heavy ion fusion reactions

Prototype Development: Context-Driven Dynamic XML Ophthalmologic Data Capture Application.

Science.gov (United States)

Peissig, Peggy; Schwei, Kelsey M; Kadolph, Christopher; Finamore, Joseph; Cancel, Efrain; McCarty, Catherine A; Okorie, Asha; Thomas, Kate L; Allen Pacheco, Jennifer; Pathak, Jyotishman; Ellis, Stephen B; Denny, Joshua C; Rasmussen, Luke V; Tromp, Gerard; Williams, Marc S; Vrabec, Tamara R; Brilliant, Murray H

2017-09-13

The capture and integration of structured ophthalmologic data into electronic health records (EHRs) has historically been a challenge. However, the importance of this activity for patient care and research is critical. The purpose of this study was to develop a prototype of a context-driven dynamic extensible markup language (XML) ophthalmologic data capture application for research and clinical care that could be easily integrated into an EHR system. Stakeholders in the medical, research, and informatics fields were interviewed and surveyed to determine data and system requirements for ophthalmologic data capture. On the basis of these requirements, an ophthalmology data capture application was developed to collect and store discrete data elements with important graphical information. The context-driven data entry application supports several features, including ink-over drawing capability for documenting eye abnormalities, context-based Web controls that guide data entry based on preestablished dependencies, and an adaptable database or XML schema that stores Web form specifications and allows for immediate changes in form layout or content. The application utilizes Web services to enable data integration with a variety of EHRs for retrieval and storage of patient data. This paper describes the development process used to create a context-driven dynamic XML data capture application for optometry and ophthalmology. The list of ophthalmologic data elements identified as important for care and research can be used as a baseline list for future ophthalmologic data collection activities. ©Peggy Peissig, Kelsey M Schwei, Christopher Kadolph, Joseph Finamore, Efrain Cancel, Catherine A McCarty, Asha Okorie, Kate L Thomas, Jennifer Allen Pacheco, Jyotishman Pathak, Stephen B Ellis, Joshua C Denny, Luke V Rasmussen, Gerard Tromp, Marc S Williams, Tamara R Vrabec, Murray H Brilliant. Originally published in JMIR Medical Informatics (http://medinform.jmir.org), 13.09.2017.

Continuous CO2 capture and MSWI fly ash stabilization, utilizing novel dynamic equipment

International Nuclear Information System (INIS)

Jiang Jianguo; Du Xuejuan; Chen Maozhe; Zhang Chang

2009-01-01

Novel dynamic equipment with gas in and out continuously was developed to study the capture capacity of CO 2 . Municipal solid waste incineration (MSWI) fly ash has a high capture rate of CO 2 in CO 2 -rich gas. Fly ash can sequester pure CO 2 rapidly, and its capacity is 16.3 g CO 2 /100 g fly ash with no water added and 21.4 g CO 2 /100 g fly ash with 20% water added. For simulated incineration gas containing 12% CO 2 , the capture rate decreased and the capacity was 13.2 g CO 2 /100 g fly ash with no water added and 18.5 g CO 2 /100 g fly ash with 20% water added. After accelerated carbonation, the C and O contents increased, indicating CO 2 capture in the fly ash; CO 2 combines with Ca(OH) 2 to form CaCO 3 , which increased the CaCO 3 content from 12.5 to 54.3%. The leaching of Pb markedly decreased from 24.48 to 0.111 mg/L. - Novel dynamic equipment designed to capture CO 2 by fly ash is more suitable for engineering application.

A dynamic capacity degradation model and its applications considering varying load for a large format Li-ion battery

International Nuclear Information System (INIS)

Ouyang, Minggao; Feng, Xuning; Han, Xuebing; Lu, Languang; Li, Zhe; He, Xiangming

2016-01-01

Highlights: • A dynamic capacity degradation model for large format Li-ion battery is proposed. • The change of the model parameters directly link with the degradation mechanisms. • The model can simulate the fading behavior of Li-ion battery under varying loads. • The model can help evaluate the longevity of a battery system under specific load. • The model can help predict the evolution of cell variations within a battery pack. - Abstract: The capacity degradation of the lithium ion battery should be well predicted during battery system design. Therefore, high-fidelity capacity degradation models that are suitable for the task of capacity prediction are required. This paper proposes a novel capacity degradation model that can simulate the degradation dynamics under varying working conditions for large-format lithium ion batteries. The degradation model is built based on a mechanistic and prognostic model (MPM) whose parameters are closely linked with the degradation mechanisms of lithium ion batteries. Chemical kinetics was set to drive the parameters of the MPM to change as capacity degradation continues. With the dynamic parameters of the MPM, the capacity predicted by the degradation model decreases as the cycle continues. Accelerated aging tests were conducted on three types of commercial lithium ion batteries to calibrate the capacity degradation model. The good fit with the experimental data indicates that the model can capture the degradation mechanisms well for different types of commercial lithium ion batteries. Furthermore, the calibrated model can be used to (1) evaluate the longevity of a battery system under a specific working load and (2) predict the evolution of cell variations within a battery pack when different cell works at different conditions. Correlated applications are discussed using the calibrated degradation model.

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

Energy Technology Data Exchange (ETDEWEB)

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

2001-02-26

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

Radiative electron capture

International Nuclear Information System (INIS)

Biggerstaff, J.A.; Appleton, B.R.; Datz, S.; Moak, C.D.; Neelavathi, V.N.; Noggle, T.S.; Ritchie, R.H.; VerBeek, H.

1975-01-01

Some data are presented for radiative electron capture by fast moving ions. The radiative electron capture spectrum is shown for O 8+ in Ag, along with the energy dependence of the capture cross-section. A discrepancy between earlier data, theoretical prediction, and the present data is pointed out. (3 figs) (U.S.)

Storage ion trap of an 'In-Flight Capture' type for precise mass measurement of radioactive nuclear reaction products and fission fragments

International Nuclear Information System (INIS)

Tarantin, N.I.

2001-01-01

Data on nuclear masses provide a basis for creating and testing various nuclear models. A tandem system of FLNR comprised of the U-400M cyclotron, the COMBAS magnetic separator and the mass-spectrometric ion trap of an 'in-flight capture' type is considered as a possible complex for producing of the short-lived nuclei in fragmentation reactions by heavy ions and for precise mass measurement of these nuclei. The plan of scientific and technical FLNR research includes a project DRIBs for producing beams of accelerated radioactive nuclear reaction products and photofission fragments. This project proposes also precise mass measurements of the fission fragment with the help of the ion trap. The in-flight entrance of the ions and their capture in the mass-spectrometric ion trap using the monochromatizing degrader, the static electric and magnetic fields and a new invention, a magnetic unidirectional transporting ventil, is considered

Dynamic culture substrate that captures a specific extracellular matrix protein in response to light

International Nuclear Information System (INIS)

Nakanishi, Jun; Nakayama, Hidekazu; Horiike, Yasuhiro; Yamaguchi, Kazuo; Garcia, Andres J

2011-01-01

The development of methods for the off-on switching of immobilization or presentation of cell-adhesive peptides and proteins during cell culture is important because such surfaces are useful for the analysis of the dynamic processes of cell adhesion and migration. This paper describes a chemically functionalized gold substrate that captures a genetically tagged extracellular matrix protein in response to light. The substrate was composed of mixed self-assembled monolayers (SAMs) of three disulfide compounds containing (i) a photocleavable poly(ethylene glycol) (PEG), (ii) nitrilotriacetic acid (NTA) and (iii) hepta(ethylene glycol) (EG 7 ). Although the NTA group has an intrinsic high affinity for oligohistidine tag (His-tag) sequences in its Ni 2+ -ion complex, the interaction was suppressed by the steric hindrance of coexisting PEG on the substrate surface. Upon photoirradiation of the substrate to release the PEG chain from the surface, this interaction became possible and hence the protein was captured at the irradiated regions, while keeping the non-specific adsorption of non-His-tagged proteins blocked by the EG 7 underbrush. In this way, we selectively immobilized a His-tagged fibronectin fragment (FNIII 7-10 ) to the irradiated regions. In contrast, when bovine serum albumin-a major serum protein-was added as a non-His-tagged protein, the surface did not permit its capture, with or without irradiation. In agreement with these results, cells were selectively attached to the irradiated patterns only when a His-tagged FNIII 7-10 was added to the medium. These results indicate that the present method is useful for studying the cellular behavior on the specific extracellular matrix protein in cell-culturing environments.

Dynamic culture substrate that captures a specific extracellular matrix protein in response to light

Energy Technology Data Exchange (ETDEWEB)

Nakanishi, Jun; Nakayama, Hidekazu; Horiike, Yasuhiro [World Premier International (WPI) Research Center Initiative, International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science - NIMS (Japan); Yamaguchi, Kazuo [Department of Chemistry, Faculty of Science and Research Institute for Photofunctionalized Materials, Kanagawa University (Japan); Garcia, Andres J, E-mail: NAKANISHI.Jun@nims.go.jp [Institute for Bioengineering and Bioscience, Woodruff School of Mechanical Engineering, Georgia Institute of Technology (United States)

2011-08-15

The development of methods for the off-on switching of immobilization or presentation of cell-adhesive peptides and proteins during cell culture is important because such surfaces are useful for the analysis of the dynamic processes of cell adhesion and migration. This paper describes a chemically functionalized gold substrate that captures a genetically tagged extracellular matrix protein in response to light. The substrate was composed of mixed self-assembled monolayers (SAMs) of three disulfide compounds containing (i) a photocleavable poly(ethylene glycol) (PEG), (ii) nitrilotriacetic acid (NTA) and (iii) hepta(ethylene glycol) (EG{sub 7}). Although the NTA group has an intrinsic high affinity for oligohistidine tag (His-tag) sequences in its Ni{sup 2+}-ion complex, the interaction was suppressed by the steric hindrance of coexisting PEG on the substrate surface. Upon photoirradiation of the substrate to release the PEG chain from the surface, this interaction became possible and hence the protein was captured at the irradiated regions, while keeping the non-specific adsorption of non-His-tagged proteins blocked by the EG{sub 7} underbrush. In this way, we selectively immobilized a His-tagged fibronectin fragment (FNIII{sub 7-10}) to the irradiated regions. In contrast, when bovine serum albumin-a major serum protein-was added as a non-His-tagged protein, the surface did not permit its capture, with or without irradiation. In agreement with these results, cells were selectively attached to the irradiated patterns only when a His-tagged FNIII{sub 7-10} was added to the medium. These results indicate that the present method is useful for studying the cellular behavior on the specific extracellular matrix protein in cell-culturing environments.

Dynamic culture substrate that captures a specific extracellular matrix protein in response to light

Directory of Open Access Journals (Sweden)

Jun Nakanishi, Hidekazu Nakayama, Kazuo Yamaguchi, Andres J Garcia and Yasuhiro Horiike

2011-01-01

Full Text Available The development of methods for the off–on switching of immobilization or presentation of cell-adhesive peptides and proteins during cell culture is important because such surfaces are useful for the analysis of the dynamic processes of cell adhesion and migration. This paper describes a chemically functionalized gold substrate that captures a genetically tagged extracellular matrix protein in response to light. The substrate was composed of mixed self-assembled monolayers (SAMs of three disulfide compounds containing (i a photocleavable poly(ethylene glycol (PEG, (ii nitrilotriacetic acid (NTA and (iii hepta(ethylene glycol (EG7. Although the NTA group has an intrinsic high affinity for oligohistidine tag (His-tag sequences in its Ni2+-ion complex, the interaction was suppressed by the steric hindrance of coexisting PEG on the substrate surface. Upon photoirradiation of the substrate to release the PEG chain from the surface, this interaction became possible and hence the protein was captured at the irradiated regions, while keeping the non-specific adsorption of non-His-tagged proteins blocked by the EG7 underbrush. In this way, we selectively immobilized a His-tagged fibronectin fragment (FNIII7–10 to the irradiated regions. In contrast, when bovine serum albumin—a major serum protein—was added as a non-His-tagged protein, the surface did not permit its capture, with or without irradiation. In agreement with these results, cells were selectively attached to the irradiated patterns only when a His-tagged FNIII7-10 was added to the medium. These results indicate that the present method is useful for studying the cellular behavior on the specific extracellular matrix protein in cell-culturing environments.

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

International Nuclear Information System (INIS)

Kimura, M.

1989-01-01

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

Design of a 'two-ion-source' charge breeder with a dual frequency ECR ion source

International Nuclear Information System (INIS)

Naik, D.; Naik, V.; Chakrabarti, A.; Dechoudhury, S.; Nayak, S.K.; Pandey, H.K.; Nakagawa, T.

2005-01-01

A charge breeder, 'two-ion-source' has been designed which consists of a surface ionisation source followed by an ECR ion source working in two-frequency mode. In this system low charge state ion beam (1+)of radioactive atoms are obtained from the first ion source close to the target chamber and landed into the ECR where those are captured and become high charged state after undergoing a multi ionisation process. This beam dynamics design has been done to optimise the maximum possible transfer of 1 + beam from the first ion source into the ECR, its full capture within the ECR zone and design of an efficient dual frequency ECR. The results shows that 1 + beam of 100 nA and 1μA (A=100) are successfully transmitted and it's beam size at the centre of ECR zone are 12 mm and 21 mm respectively, which are very less than 65 mm width ECR zone of dual frequency ECR heating at 14 GHz and 10 GHz. (author)

Ball lightning dynamics and stability at moderate ion densities

International Nuclear Information System (INIS)

Morrow, R

2017-01-01

A general mechanism is presented for the dynamics and structure of ball lightning and for the maintenance of the ball lightning structure for several seconds. Results are obtained using a spherical geometry for air at atmospheric pressure, by solving the continuity equations for electrons, positive ions and negative ions coupled with Poisson’s equation. A lightning strike can generate conditions in the lightning channel with a majority of positive nitrogen ions, and a minority of negative oxygen ions and electrons. The calculations are initiated with electrons included; however, at the moderate ion densities chosen the electrons are rapidly lost to form negative ions, and after 1 µ s their influence on the ion dynamics is negligible. Further development after 1 µ s is followed using a simpler set of equations involving only positive ions and negative ions, but including ion diffusion. The space-charge electric field generated by the majority positive ions drives them from the centre of the distribution and drives the minority negative ions and electrons towards the centre of the distribution. In the central region the positive and negative ion distributions eventually overlap exactly and their space-charge fields cancel resulting in zero electric field, and the plasma ball formed is quite stable for a number of seconds. The formation of such plasma balls is not critically dependent on the initial diameter of the ion distributions, or the initial density of minority negative ions. The ion densities decrease relatively slowly due to mutual neutralization of positive and negative ions. The radiation from this neutralization process involving positive nitrogen ions and negative oxygen ions is not sufficient to account for the reported luminosity of ball lightning and some other source of luminosity is shown to be required; the plasma ball model used could readily incorporate other ions in order to account for the luminosity and range of colours reported for ball

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

International Nuclear Information System (INIS)

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

2002-01-01

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

Double electron transfer in ion-atom collisions

International Nuclear Information System (INIS)

Martinez, A.E

1990-01-01

Continuum distorted wave (CDW) and CDW-EIS (electron-ion scattering) approximations are used to study the resonant double capture by collision of alpha particles on He targets for intermediate and high energies. Calculations of total cross-sections based on the Independent Event Approximation are presented. A good agreement with experimental results was found, even without the inclusion of the dynamic and angular correlation of captured electrons. (Author). 11 refs., 1 fig

EJECTION AND CAPTURE DYNAMICS IN RESTRICTED THREE-BODY ENCOUNTERS

International Nuclear Information System (INIS)

Kobayashi, Shiho; Hainick, Yanir; Sari, Re'em; Rossi, Elena M.

2012-01-01

We study the tidal disruption of binaries by a massive point mass (e.g., the black hole at the Galactic center), and we discuss how the ejection and capture preference between unequal-mass binary members depends on which orbit they approach the massive object. We show that the restricted three-body approximation provides a simple and clear description of the dynamics. The orbit of a binary with mass m around a massive object M should be almost parabolic with an eccentricity of |1 – e| ∼ 1/3 1/3 times the binary rotation velocity, it would be abruptly disrupted, and the energy change at the encounter can be evaluated in a simple disruption model. We evaluate the probability distributions for the ejection and capture of circular binary members and for the final energies. In principle, for any hyperbolic (elliptic) orbit, the heavier member has more chance to be ejected (captured), because it carries a larger fraction of the orbital energy. However, if the orbital energy is close to zero, the difference between the two members becomes small, and there is practically no ejection and capture preferences. The preference becomes significant when the orbital energy is comparable to the typical energy change at the encounter. We discuss its implications to hypervelocity stars and irregular satellites around giant planets.

Dynamical components in the heavy-ion optical

International Nuclear Information System (INIS)

Hussein, M.S.

1980-03-01

Dynamical components in the heavy-ion optical potential are calculated. Special emphasis is given to the dynamical components resulting from coupling to inelastic channels at sub-barrier energies. The component arising from both Coulomb and nuclear coupling is calculated to lowest order using the one-energy-shell approximation for the channel Green's function. A similar approximation is used to calculate the dynamical components arising from particle transfer coupling. (Author) [pt

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

International Nuclear Information System (INIS)

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

2014-01-01

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

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

International Nuclear Information System (INIS)

Hanafy, H.

2005-01-01

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

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

International Nuclear Information System (INIS)

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

1995-01-01

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

Effect of total pressure on sulfur capture of Ca-ion exchanged coal; Kaatsu jokenka ni okeru Ca-tanjitan no datsuryu koka

Energy Technology Data Exchange (ETDEWEB)

Lin, S.; Benjamin, G.; Abe, H.; Harano, A.; Takarada, T. [Gunma University, Gunma (Japan). Faculty of Engineering

1996-10-28

In relation to coal gasification and combustion under high pressure as highly efficient coal utilization, the effect of total pressure and sintering on the SO2 capture ability of Ca-ion exchanged coal and other desulfurizing agents were studied. In experiment, specimens were filled into a small pressurized reactor to heat them under high-pressure N2 atmosphere. After the completion of combustion reaction of char at 850{degree}C, SO2, CO2 and CO gases were measured at an outlet while flowing SO2/N2. As the experimental result, all of the S content in Ca-ion exchanged coal was not absorbed by Ca content in coal during pyrolysis and combustion, resulting in discharge of 36% of the S content. Since Ca-ion exchanged coal is fast in combustion reaction, most of the S content was desulfurized by coal ash. The ash content yielded from Ca-ion exchanged coal was more excellent in SO2 capture ability than limestone even under higher pressure. In the case of CO2 partial pressure lower than equilibrium CO2 pressure for CaCO3 decomposition, the capture ability decreased with an increase in total pressure, while in higher CO2 partial pressure, it was improved. 1 ref., 7 figs., 2 tabs.

Multicharged Ion-induced simple molecule fragmentation dynamics

International Nuclear Information System (INIS)

Tarisien, M.

2003-10-01

The aim of this work is to study the dynamics of swift multicharged ion-induced fragmentation of diatomic (CO) and triatomic (CO 2 ) molecules. Performed at the GANIL facility, this study used the Recoil Ion Momentum Spectroscopy technique (RIMS), which consists of a time-of-flight mass spectrometer, coupled with a multi-hit capability position sensitive detector (delay line anode). The high-resolution measurement of the kinetic energy distribution released (KER) during the CO fragmentation points out the limitation of the Coulomb Explosion Model, revealing, for example, the di-cation CO 2 + electronic state contribution in the case of C + /O + fragmentation pathway. Furthermore, the multi-ionization cross section dependence with the orientation of the internuclear axis of CO is compared with a geometrical model calculation. Finally, different behaviours are observed for the dissociation dynamics of a triatomic molecule (CO 2 ). While triple ionization leads mainly to a synchronous concerted fragmentation dynamics, a weak fraction of dissociating molecule follows a sequential dynamics involving CO 2 + metastable states. In the case of double ionization, (CO 2 ) 2+ di-cation dissociation dynamics is asynchronously concerted and has been interpreted using a simple model involving an asymmetrical vibration of the molecule. (author)

Dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons

Science.gov (United States)

Saha, Asit; Pal, Nikhil; Chatterjee, Prasanta

2014-10-01

The dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons has been investigated in the framework of perturbed and non-perturbed Kadomtsev-Petviashili (KP) equations. Applying the reductive perturbation technique, we have derived the KP equation in electron-positron-ion magnetoplasma with kappa distributed electrons and positrons. Bifurcations of ion acoustic traveling waves of the KP equation are presented. Using the bifurcation theory of planar dynamical systems, the existence of the solitary wave solutions and the periodic traveling wave solutions has been established. Two exact solutions of these waves have been derived depending on the system parameters. Then, using the Hirota's direct method, we have obtained two-soliton and three-soliton solutions of the KP equation. The effect of the spectral index κ on propagations of the two-soliton and the three-soliton has been shown. Considering an external periodic perturbation, we have presented the quasi periodic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas.

Dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons

Energy Technology Data Exchange (ETDEWEB)

Saha, Asit, E-mail: asit-saha123@rediffmail.com, E-mail: prasantachatterjee1@rediffmail.com [Department of Mathematics, Sikkim Manipal Institute of Technology, Majitar, Rangpo, East-Sikkim 737136 (India); Department of Mathematics, Siksha Bhavana, Visva Bharati University, Santiniketan-731235 (India); Pal, Nikhil; Chatterjee, Prasanta, E-mail: asit-saha123@rediffmail.com, E-mail: prasantachatterjee1@rediffmail.com [Department of Mathematics, Siksha Bhavana, Visva Bharati University, Santiniketan-731235 (India)

2014-10-15

The dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons has been investigated in the framework of perturbed and non-perturbed Kadomtsev-Petviashili (KP) equations. Applying the reductive perturbation technique, we have derived the KP equation in electron-positron-ion magnetoplasma with kappa distributed electrons and positrons. Bifurcations of ion acoustic traveling waves of the KP equation are presented. Using the bifurcation theory of planar dynamical systems, the existence of the solitary wave solutions and the periodic traveling wave solutions has been established. Two exact solutions of these waves have been derived depending on the system parameters. Then, using the Hirota's direct method, we have obtained two-soliton and three-soliton solutions of the KP equation. The effect of the spectral index κ on propagations of the two-soliton and the three-soliton has been shown. Considering an external periodic perturbation, we have presented the quasi periodic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas.

Single capture and transfer ionization in collisions of Clq+ projectile ions incident on helium

International Nuclear Information System (INIS)

Wong, K.L.; Ben-Itzhak, I.; Cocke, C.L.; Giese, J.P.; Richard, P.

1995-01-01

The Kansas State University linac has been used to measure the ratio of the cross sections for the processes of transfer ionization (TI) and single capture (SC) for 2 MeV/amu Cl q+ where q=7, 9, 13, 14, and 15 projectile ions incident on a helium target. The ratio was determined using a helium gas jet target by measuring coincidences between projectile-ion and recoil-ion final charge states. The σ TI /σ SC for Cl q+ were compared to measurements of bare F 9+ and hydrogenlike F 8+ and O 7+ taken at the same velocity. The ratios deviate from a q 2 scaling which is predicted in the perturbative regime. This deviation is attributed to screening by the projectile electrons for low q=7 and 9, and to the collision being non-perturbative for high q. A possible saturation effect in the ratio was observed for q similar 14. (orig.)

Development of high intensity ion sources for a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy

International Nuclear Information System (INIS)

Bergueiro, J.; Igarzabal, M.; Suarez Sandin, J.C.; Somacal, H.R.; Thatar Vento, V.; Huck, H.; Valda, A.A.; Repetto, M.

2011-01-01

Several ion sources have been developed and an ion source test stand has been mounted for the first stage of a Tandem-Electrostatic-Quadrupole facility For Accelerator-Based Boron Neutron Capture Therapy. A first source, designed, fabricated and tested is a dual chamber, filament driven and magnetically compressed volume plasma proton ion source. A 4 mA beam has been accelerated and transported into the suppressed Faraday cup. Extensive simulations of the sources have been performed using both 2D and 3D self-consistent codes.

Development of high intensity ion sources for a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy

Energy Technology Data Exchange (ETDEWEB)

Bergueiro, J. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica (Argentina)] [CONICET, Buenos Aires (Argentina); Igarzabal, M.; Suarez Sandin, J.C. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica (Argentina); Somacal, H.R. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica (Argentina)] [Escuela de Ciencia y Tecnologia, Universidad Nacional de San Martin (Argentina); Thatar Vento, V. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica (Argentina)] [CONICET, Buenos Aires (Argentina); Huck, H.; Valda, A.A. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica (Argentina)] [Escuela de Ciencia y Tecnologia, Universidad Nacional de San Martin (Argentina); Repetto, M. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica (Argentina)

2011-12-15

Several ion sources have been developed and an ion source test stand has been mounted for the first stage of a Tandem-Electrostatic-Quadrupole facility For Accelerator-Based Boron Neutron Capture Therapy. A first source, designed, fabricated and tested is a dual chamber, filament driven and magnetically compressed volume plasma proton ion source. A 4 mA beam has been accelerated and transported into the suppressed Faraday cup. Extensive simulations of the sources have been performed using both 2D and 3D self-consistent codes.

Beam dynamics in heavy ion induction LINACS

International Nuclear Information System (INIS)

Smith, L.

1981-10-01

Interest in the use of an induction linac to accelerate heavy ions for the purpose of providing the energy required to initiate an inertially confined fusion reaction has stimulated a theoretical effort to investigate various beam dynamical effects associated with high intensity heavy ion beams. This paper presents a summary of the work that has been done so far; transverse, longitudinal and coupled longitudinal transverse effects are discussed

Radiative electron capture studied in relativistic heavy-ion atom collisions

International Nuclear Information System (INIS)

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

1994-08-01

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

Dynamic imaging of cell-free and cell-associated viral capture in mature dendritic cells.

Science.gov (United States)

Izquierdo-Useros, Nuria; Esteban, Olga; Rodriguez-Plata, Maria T; Erkizia, Itziar; Prado, Julia G; Blanco, Julià; García-Parajo, Maria F; Martinez-Picado, Javier

2011-12-01

Dendritic cells (DCs) capture human immunodeficiency virus (HIV) through a non-fusogenic mechanism that enables viral transmission to CD4(+) T cells, contributing to in vivo viral dissemination. Although previous studies have provided important clues to cell-free viral capture by mature DCs (mDCs), dynamic and kinetic insight on this process is still missing. Here, we used three-dimensional video microscopy and single-particle tracking approaches to dynamically dissect both cell-free and cell-associated viral capture by living mDCs. We show that cell-free virus capture by mDCs operates through three sequential phases: virus binding through specific determinants expressed in the viral particle, polarized or directional movements toward concrete regions of the cell membrane and virus accumulation in a sac-like structure where trapped viral particles display a hindered diffusive behavior. Moreover, real-time imaging of cell-associated viral transfer to mDCs showed a similar dynamics to that exhibited by cell-free virus endocytosis leading to viral accumulation in compartments. However, cell-associated HIV type 1 transfer to mDCs was the most effective pathway, boosted throughout enhanced cellular contacts with infected CD4(+) T cells. Our results suggest that in lymphoid tissues, mDC viral uptake could occur either by encountering cell-free or cell-associated virus produced by infected cells generating the perfect scenario to promote HIV pathogenesis and impact disease progression. © 2011 John Wiley & Sons A/S.

The dynamics of electron and ion holes in a collisionless plasma

Directory of Open Access Journals (Sweden)

B. Eliasson

2005-01-01

Full Text Available We present a review of recent analytical and numerical studies of the dynamics of electron and ion holes in a collisionless plasma. The new results are based on the class of analytic solutions which were found by Schamel more than three decades ago, and which here work as initial conditions to numerical simulations of the dynamics of ion and electron holes and their interaction with radiation and the background plasma. Our analytic and numerical studies reveal that ion holes in an electron-ion plasma can trap Langmuir waves, due the local electron density depletion associated with the negative ion hole potential. Since the scale-length of the ion holes are on a relatively small Debye scale, the trapped Langmuir waves are Landau damped. We also find that colliding ion holes accelerate electron streams by the negative ion hole potentials, and that these streams of electrons excite Langmuir waves due to a streaming instability. In our Vlasov simulation of two colliding ion holes, the holes survive the collision and after the collision, the electron distribution becomes flat-topped between the two ion holes due to the ion hole potentials which work as potential barriers for low-energy electrons. Our study of the dynamics between electron holes and the ion background reveals that standing electron holes can be accelerated by the self-created ion cavity owing to the positive electron hole potential. Vlasov simulations show that electron holes are repelled by ion density minima and attracted by ion density maxima. We also present an extension of Schamel's theory to relativistically hot plasmas, where the relativistic mass increase of the accelerated electrons have a dramatic effect on the electron hole, with an increase in the electron hole potential and in the width of the electron hole. A study of the interaction between electromagnetic waves with relativistic electron holes shows that electromagnetic waves can be both linearly and nonlinearly

Simulation of dynamic magnetic particle capture and accumulation around a ferromagnetic wire

Energy Technology Data Exchange (ETDEWEB)

Choomphon-anomakhun, Natthaphon [Department of Physics, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330 (Thailand); Ebner, Armin D. [Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Natenapit, Mayuree [Department of Physics, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330 (Thailand); Ritter, James A. [Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

2017-04-15

A new approach for modeling high gradient magnetic separation (HGMS)-type systems during the time-dependent capture and accumulation of magnetic particles by a ferromagnetic wire was developed. This new approach assumes the fluid (slurry) viscosity, comprised of water and magnetic particles, is a function of the magnetic particle concentration in the fluid, with imposed maxima on both the particle concentration and fluid viscosity to avoid unrealistic limits. In 2-D, the unsteady-state Navier-Stokes equations for compressible fluid flow and the unsteady-state continuity equations applied separately to the water and magnetic particle phases in the slurry were solved simultaneously, along with the Laplace equations for the magnetic potential applied separately to the slurry and wire, to evaluate the velocities and concentrations around the wire in a narrow channel using COMSOL Multiphysics. The results from this model revealed very realistic magnetically attractive and repulsive zones forming in time around the wire. These collection zones formed their own impermeable viscous phase during accumulation that was also magnetic with its area and magnetism impacting locally both the fluid flow and magnetic fields around the wire. These collection zones increased with an increase in the applied magnetic field. For a given set of conditions, the capture ability peaked and then decreased to zero at infinite time during magnetic particle accumulation in the collection zones. Predictions of the collection efficiency from a steady-state, clean collector, trajectory model could not show this behavior; it also agreed only qualitatively with the dynamic model and then only at the early stages of collection and more so at a higher applied magnetic field. Also, the collection zones decreased in size when the accumulation regions included magnetic particle magnetization (realistic) compared to when they excluded it (unrealistic). Overall, this might be the first time a mathematical

Development of high intensity ion sources for a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy.

Science.gov (United States)

Bergueiro, J; Igarzabal, M; Sandin, J C Suarez; Somacal, H R; Vento, V Thatar; Huck, H; Valda, A A; Repetto, M; Kreiner, A J

2011-12-01

Several ion sources have been developed and an ion source test stand has been mounted for the first stage of a Tandem-Electrostatic-Quadrupole facility For Accelerator-Based Boron Neutron Capture Therapy. A first source, designed, fabricated and tested is a dual chamber, filament driven and magnetically compressed volume plasma proton ion source. A 4 mA beam has been accelerated and transported into the suppressed Faraday cup. Extensive simulations of the sources have been performed using both 2D and 3D self-consistent codes. Copyright © 2011 Elsevier Ltd. All rights reserved.

Aqueous vanadium ion dynamics relevant to bioinorganic chemistry: A review.

Science.gov (United States)

Kustin, Kenneth

2015-06-01

Aqueous solutions of the four highest vanadium oxidation states exhibit four diverse colors, which only hint at the diverse reactions that these ions can undergo. Cationic vanadium ions form complexes with ligands; anionic vanadium ions form complexes with ligands and self-react to form isopolyanions. All vanadium species undergo oxidation-reduction reactions. With a few exceptions, elucidation of the dynamics of these reactions awaited the development of fast reaction techniques before the kinetics of elementary ligation, condensation, reduction, and oxidation of the aqueous vanadium ions could be investigated. As the biological roles played by endogenous and therapeutic vanadium expand, it is appropriate to bring the results of the diverse kinetics studies under one umbrella. To achieve this goal this review presents a systematic examination of elementary aqueous vanadium ion dynamics. Copyright © 2014 Elsevier Inc. All rights reserved.

IBiSA_Tools: A Computational Toolkit for Ion-Binding State Analysis in Molecular Dynamics Trajectories of Ion Channels.

Directory of Open Access Journals (Sweden)

Kota Kasahara

Full Text Available Ion conduction mechanisms of ion channels are a long-standing conundrum. Although the molecular dynamics (MD method has been extensively used to simulate ion conduction dynamics at the atomic level, analysis and interpretation of MD results are not straightforward due to complexity of the dynamics. In our previous reports, we proposed an analytical method called ion-binding state analysis to scrutinize and summarize ion conduction mechanisms by taking advantage of a variety of analytical protocols, e.g., the complex network analysis, sequence alignment, and hierarchical clustering. This approach effectively revealed the ion conduction mechanisms and their dependence on the conditions, i.e., ion concentration and membrane voltage. Here, we present an easy-to-use computational toolkit for ion-binding state analysis, called IBiSA_tools. This toolkit consists of a C++ program and a series of Python and R scripts. From the trajectory file of MD simulations and a structure file, users can generate several images and statistics of ion conduction processes. A complex network named ion-binding state graph is generated in a standard graph format (graph modeling language; GML, which can be visualized by standard network analyzers such as Cytoscape. As a tutorial, a trajectory of a 50 ns MD simulation of the Kv1.2 channel is also distributed with the toolkit. Users can trace the entire process of ion-binding state analysis step by step. The novel method for analysis of ion conduction mechanisms of ion channels can be easily used by means of IBiSA_tools. This software is distributed under an open source license at the following URL: http://www.ritsumei.ac.jp/~ktkshr/ibisa_tools/.

Structure and Dynamics of Negative Ions

International Nuclear Information System (INIS)

None

2000-01-01

This report describes progress made during the final three-year grant period 1997-2000. During this period, we experimentally investigated the structure and dynamics of negative ions by detaching the outermost electron in controlled processes induced by photon-, electron- and heavy particle-impact. In this manner we studied, at a fundamental level, the role of electron correlation in the structure and dynamics of simple, few-particle atomic systems. Our measurements have provided sensitive tests of the ability of theory to go beyond the independent electron model

Static harmonization of dynamically harmonized Fourier transform ion cyclotron resonance cell.

Science.gov (United States)

Zhdanova, Ekaterina; Kostyukevich, Yury; Nikolaev, Eugene

2017-08-01

Static harmonization in the Fourier transform ion cyclotron resonance cell improves the resolving power of the cell and prevents dephasing of the ion cloud in the case of any trajectory of the charged particle, not necessarily axisymmetric cyclotron (as opposed to dynamic harmonization). We reveal that the Fourier transform ion cyclotron resonance cell with dynamic harmonization (paracell) is proved to be statically harmonized. The volume of the statically harmonized potential distribution increases with an increase in the number of trap segments.

Interatomic Coulombic electron capture

International Nuclear Information System (INIS)

Gokhberg, K.; Cederbaum, L. S.

2010-01-01

In a previous publication [K. Gokhberg and L. S. Cederbaum, J. Phys. B 42, 231001 (2009)] we presented the interatomic Coulombic electron capture process--an efficient electron capture mechanism by atoms and ions in the presence of an environment. In the present work we derive and discuss the mechanism in detail. We demonstrate thereby that this mechanism belongs to a family of interatomic electron capture processes driven by electron correlation. In these processes the excess energy released in the capture event is transferred to the environment and used to ionize (or to excite) it. This family includes the processes where the capture is into the lowest or into an excited unoccupied orbital of an atom or ion and proceeds in step with the ionization (or excitation) of the environment, as well as the process where an intermediate autoionizing excited resonance state is formed in the capturing center which subsequently deexcites to a stable state transferring its excess energy to the environment. Detailed derivation of the asymptotic cross sections of these processes is presented. The derived expressions make clear that the environment assisted capture processes can be important for many systems. Illustrative examples are presented for a number of model systems for which the data needed to construct the various capture cross sections are available in the literature.

Molecular dynamics and brownian dynamics investigation of ion permeation and anesthetic halothane effects on a proton-gated ion channel.

Science.gov (United States)

Cheng, Mary Hongying; Coalson, Rob D; Tang, Pei

2010-11-24

Bacterial Gloeobacter violaceus pentameric ligand-gated ion channel (GLIC) is activated to cation permeation upon lowering the solution pH. Its function can be modulated by anesthetic halothane. In the present work, we integrate molecular dynamics (MD) and Brownian dynamics (BD) simulations to elucidate the ion conduction, charge selectivity, and halothane modulation mechanisms in GLIC, based on recently resolved X-ray crystal structures of the open-channel GLIC. MD calculations of the potential of mean force (PMF) for a Na(+) revealed two energy barriers in the extracellular domain (R109 and K38) and at the hydrophobic gate of transmembrane domain (I233), respectively. An energy well for Na(+) was near the intracellular entrance: the depth of this energy well was modulated strongly by the protonation state of E222. The energy barrier for Cl(-) was found to be 3-4 times higher than that for Na(+). Ion permeation characteristics were determined through BD simulations using a hybrid MD/continuum electrostatics approach to evaluate the energy profiles governing the ion movement. The resultant channel conductance and a near-zero permeability ratio (P(Cl)/P(Na)) were comparable to experimental data. On the basis of these calculations, we suggest that a ring of five E222 residues may act as an electrostatic gate. In addition, the hydrophobic gate region may play a role in charge selectivity due to a higher dehydration energy barrier for Cl(-) ions. The effect of halothane on the Na(+) PMF was also evaluated. Halothane was found to perturb salt bridges in GLIC that may be crucial for channel gating and open-channel stability, but had no significant impact on the single ion PMF profiles.

Preferential solvation, ion pairing, and dynamics of concentrated aqueous solutions of divalent metal nitrate salts

Science.gov (United States)

Yadav, Sushma; Chandra, Amalendu

2017-12-01

We have investigated the characteristics of preferential solvation of ions, structure of solvation shells, ion pairing, and dynamics of aqueous solutions of divalent alkaline-earth metal nitrate salts at varying concentration by means of molecular dynamics simulations. Hydration shell structures and the extent of preferential solvation of the metal and nitrate ions in the solutions are investigated through calculations of radial distribution functions, tetrahedral ordering, and also spatial distribution functions. The Mg2+ ions are found to form solvent separated ion-pairs while the Ca2+ and Sr2+ ions form contact ion pairs with the nitrate ions. These findings are further corroborated by excess coordination numbers calculated through Kirkwood-Buff G factors for different ion-ion and ion-water pairs. The ion-pairing propensity is found to be in the order of Mg(NO3) 2 lead to the presence of substantial dynamical heterogeneity in these solutions of strongly interacting ions. The current study helps us to understand the molecular details of hydration structure, ion pairing, and dynamics of water in the solvation shells and also of ion diffusion in aqueous solutions of divalent metal nitrate salts.

Longitudinal and transverse dynamics of ions from residual gas in an electron accelerator

Science.gov (United States)

Gamelin, A.; Bruni, C.; Radevych, D.

2018-05-01

The ion cloud produced from residual gas in an electron accelerator can degrade machine performances and produce instabilities. The ion dynamics in an accelerator is governed by the beam-ion interaction, magnetic fields and eventual mitigation strategies. Due to the fact that the beam has a nonuniform transverse size along its orbit, the ions move longitudinally and accumulate naturally at some points in the accelerator. In order to design effective mitigation strategies it is necessary to understand the ion dynamics not only in the transverse plane but also in the longitudinal direction. After introducing the physics behind the beam-ion interaction, we show how to get accumulation points for a realistic electron storage ring lattice. Simulations of the ion cloud dynamics, including the effect of magnetic fields on the ions, clearing electrodes and clearing gaps are shown. Longitudinal ion trapping due to the magnetic mirror effect in the dipole fringe fields is also detailed. Finally, the effectiveness of clearing electrode using longitudinal clearing fields is discussed and compared to clearing electrodes producing transverse field only.

Molecular dynamics simulations of ion range profiles for heavy ions in light targets

Energy Technology Data Exchange (ETDEWEB)

Lan, C. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); State Key Laboratory of Nuclear Physics and Technology, Peking University, 100871 (China); Xue, J.M. [State Key Laboratory of Nuclear Physics and Technology, Peking University, 100871 (China); Zhang, Y., E-mail: Zhangy1@ornl.gov [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Morris, J.R. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Zhu, Z. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Gao, Y.; Wang, Y.G.; Yan, S. [State Key Laboratory of Nuclear Physics and Technology, Peking University, 100871 (China); Weber, W.J. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2012-09-01

The determination of stopping powers for slow heavy ions in targets containing light elements is important to accurately describe ion-solid interactions, evaluate ion irradiation effects and predict ion ranges for device fabrication and nuclear applications. Recently, discrepancies of up to 40% between the experimental results and SRIM (Stopping and Range of Ions in Matter) predictions of ion ranges for heavy ions with medium and low energies (<{approx}25 keV/nucleon) in light elemental targets have been reported. The longer experimental ion ranges indicate that the stopping powers used in the SRIM code are overestimated. Here, a molecular dynamics simulation scheme is developed to calculate the ion ranges of heavy ions in light elemental targets. Electronic stopping powers generated from both a reciprocity approach and the SRIM code are used to investigate the influence of electronic stopping on ion range profiles. The ion range profiles for Au and Pb ions in SiC and Er ions in Si, with energies between 20 and 5250 keV, are simulated. The simulation results show that the depth profiles of implanted ions are deeper and in better agreement with the experiments when using the electronic stopping power values derived from the reciprocity approach. These results indicate that the origin of the discrepancy in ion ranges between experimental results and SRIM predictions in the low energy region may be an overestimation of the electronic stopping powers used in SRIM.

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Nuclear dynamics in heavy ion induced fusion-fission reactions

International Nuclear Information System (INIS)

Kapoor, S.S.

1992-01-01

Heavy ion induced fission and fission-like reactions evolve through a complex nuclear dynamics encountered in the medium energy nucleus-nucleus collisions. In the recent years, measurements of the fragment-neutron and fragment-charged particle angular correlations in heavy ion induced fusion-fission reactions, have provided new information on the dynamical times of nuclear deformations of the initial dinuclear complex to the fission saddle point and the scission point. From the studies of fragment angular distributions in heavy ion induced fission it has been possible to infer the relaxation times of the dinuclear complex in the K-degree of freedom and our recent measurements on the entrance channel dependence of fragment anisotropies have provided an experimental signature of the presence of fissions before K-equilibration. This paper reviews recent experimental and theoretical status of the above studies with particular regard to the questions relating to dynamical times, nuclear dissipation and the effect of nuclear dissipation on the K-distributions at the fission saddle in completely equilibrated compound nucleus. (author). 19 refs., 9 figs

Dynamical chaos of plasma ions in electrostatic waves

International Nuclear Information System (INIS)

Fasoli, A.; Kleiber, R.; Tran, M.Q.; Paris, P.J.; Skiff, F.

1992-09-01

Chaos generated by the interaction between charged particles and electrostatic plasma waves has been observed in a linear magnetized plasma. The macroscopic wave properties, the kinetic ion dielectric response and the microscopic heating mechanisms have been investigated via optical diagnostic techniques based on laser induced fluorescence. Observations of test-particle dynamical evolution indicate an exponential separation of initially close ion trajectories. (author) 5 figs., 20 refs

Lithium-ion battery dynamic model for wide range of operating conditions

DEFF Research Database (Denmark)

Stroe, Ana-Irina; Stroe, Daniel-Ioan; Swierczynski, Maciej Jozef

2017-01-01

In order to analyze the dynamic behavior of a Lithium-ion (Li-ion) battery and to determine their suitability for various applications, battery models are needed. An equivalent electrical circuit model is the most common way of representing the behavior of a Li-ion battery. There are different...... characterization tests performed for a wide range of operating conditions (temperature, load current and state-of-charge) on a commercial available 13Ah high-power lithium titanate oxide battery cell. The obtained results were used to parametrize the proposed dynamic model of the battery cell. To assess...

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

International Nuclear Information System (INIS)

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

1998-01-01

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

The molecular dynamics simulation of ion-induced ripple growth

International Nuclear Information System (INIS)

Suele, P.; Heinig, K.-H.

2009-01-01

The wavelength-dependence of ion-sputtering induced growth of repetitive nanostructures, such as ripples has been studied by molecular dynamics (MD) simulations in Si. The early stage of the ion erosion driven development of ripples has been simulated on prepatterned Si stripes with a wavy surface. The time evolution of the height function and amplitude of the sinusoidal surface profile has been followed by simulated ion-sputtering. According to Bradley-Harper (BH) theory, we expect correlation between the wavelength of ripples and the stability of them. However, we find that in the small ripple wavelength (λ) regime BH theory fails to reproduce the results obtained by molecular dynamics. We find that at short wavelengths (λ 35 nm is stabilized in accordance with the available experimental results. According to the simulations, few hundreds of ion impacts in λ long and few nanometers wide Si ripples are sufficient for reaching saturation in surface growth for for λ>35 nm ripples. In another words, ripples in the long wavelength limit seems to be stable against ion-sputtering. A qualitative comparison of our simulation results with recent experimental data on nanopatterning under irradiation is attempted.

Electron-capture cross sections for low-energy highly charged neon and argon ions from molecular and atomic hydrogen

International Nuclear Information System (INIS)

Can, C.; Gray, T.J.; Varghese, S.L.; Hall, J.M.; Tunnell, L.N.

1985-01-01

Electron-capture cross sections for low-velocity (10 6 --10 7 cm/s) highly charged Ne/sup q/+ (2< or =q< or =7) and Ar/sup q/+ (2< or =q< or =10)= projectiles incident on molecular- and atomic-hydrogen targets have been measured. A recoil-ion source that used the collisions of fast heavy ions (1 MeV/amu) with target gas atoms was utilized to produce slow highly charged ions. Atomic hydrogen was produced by dissociating hydrogen molecules in a high-temperature oven. Measurements and analysis of the data for molecular- and atomic-hydrogen targets are discussed in detail. The measured absolute cross sections are compared with published data and predictions of theoretical models

Nonperturbative electromagnetic muon-pair production with capture in peripheral relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Wells, J.C.

1991-01-01

We discuss preliminary calculations of impact-parameter-dependent probabilities and cross sections for muon-pair production with capture of the negative muon into the K-shell of the target caused by the time-dependent electromagnetic fields generated in peripheral relativistic heavy-ion collisions. Our approach is nonperturbative in that we calculate probabilities by solving the time-dependent Dirac equation on a three-dimensional Cartesian lattice using the basis-spline collocation method. Use of the axial gauge for the electromagnetic potentials produces an interaction easier to implement on the lattice than the Lorentz gauge. 19 refs., 5 figs

ION ACOUSTIC TURBULENCE, ANOMALOUS TRANSPORT, AND SYSTEM DYNAMICS IN HALL EFFECT THRUSTERS

Science.gov (United States)

2017-06-30

NUMBER (Include area code) 30 June 2017 Briefing Charts 26 May 2017 - 30 June 2017 ION ACOUSTIC TURBULENCE, ANOMALOUS TRANSPORT, AND SYSTEM DYNAMICS ...Robert Martin N/A ION ACOUSTIC TURBULENCE, ANOMALOUS TRANSPORT, AND SYSTEM DYNAMICS IN HALL EFFECT THRUSTERS Robert Martin1, Jonathan Tran2 1AIR FORCE...Approved for Public Release; Distribution is Unlimited. PA# 17394 1 / 13 OUTLINE 1 INTRODUCTION 2 TRANSPORT 3 DYNAMIC SYSTEM 4 SUMMARY AND CONCLUSION

Dynamical ion transfer between coupled Coulomb crystals in a double-well potential.

Science.gov (United States)

Klumpp, Andrea; Zampetaki, Alexandra; Schmelcher, Peter

2017-09-01

We investigate the nonequilibrium dynamics of coupled Coulomb crystals of different sizes trapped in a double well potential. The dynamics is induced by an instantaneous quench of the potential barrier separating the two crystals. Due to the intra- and intercrystal Coulomb interactions and the asymmetric population of the potential wells, we observe a complex reordering of ions within the two crystals as well as ion transfer processes from one well to the other. The study and analysis of the latter processes constitutes the main focus of this work. In particular, we examine the dependence of the observed ion transfers on the quench amplitude performing an analysis for different crystalline configurations ranging from one-dimensional ion chains via two-dimensional zigzag chains and ring structures to three-dimensional spherical structures. Such an analysis provides us with the means to extract the general principles governing the ion transfer dynamics and we gain some insight on the structural disorder caused by the quench of the barrier height.

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

International Nuclear Information System (INIS)

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

1987-01-01

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

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

Science.gov (United States)

Bertulani, C. A.

2018-01-01

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

Surface dynamics of voltage-gated ion channels

Science.gov (United States)

Heine, Martin; Ciuraszkiewicz, Anna; Voigt, Andreas; Heck, Jennifer; Bikbaev, Arthur

2016-01-01

ABSTRACT Neurons encode information in fast changes of the membrane potential, and thus electrical membrane properties are critically important for the integration and processing of synaptic inputs by a neuron. These electrical properties are largely determined by ion channels embedded in the membrane. The distribution of most ion channels in the membrane is not spatially uniform: they undergo activity-driven changes in the range of minutes to days. Even in the range of milliseconds, the composition and topology of ion channels are not static but engage in highly dynamic processes including stochastic or activity-dependent transient association of the pore-forming and auxiliary subunits, lateral diffusion, as well as clustering of different channels. In this review we briefly discuss the potential impact of mobile sodium, calcium and potassium ion channels and the functional significance of this for individual neurons and neuronal networks. PMID:26891382

Dynamics of fast ions in Tokamaks

International Nuclear Information System (INIS)

Helander, P.

1994-01-01

Fast ions play a prominent role in the heating of tokamak plasmas by, e.g. neutral-beam injection, ion-cyclotron-resonance heating, and alpha-particle heating. In this thesis, a number of physical and mathematical problems concerning the dynamics of fast ions in tokamaks are addressed. First, the motion under adiabatic perturbations is studied. The frequencies of instabilities excited in tokamaks sometimes vary slowly with time. The existence of an adiabatic invariant of particle motion in such circumstances is shown to lead to a rapid convection of particles in the radial direction. Generalized adiabatic invariants are constructed for systems where the slowly varying parameter is subjected to small, but rapidly varying, fluctuations. Second, the onset of stochastic motion under resonant perturbations is considered. It is shown that the finite width of fast-ion drift orbits significantly affects the threshold for stochastic motion caused by magnetic field ripple or ion-cyclotron-resonance heating. Finite-orbit-width effects are also shown to reduce the strength of resonant interaction between alpha particles and internal kink modes. Third, the diffusive motion in the stochastic regime is analysed mathematically. Monte Carlo operators for the motion on long time-scales are constructed, and the validity of the quasilinear diffusion coefficient is examined. Finally, the effects of close ion collisions are investigated. It is demonstrated that close encounters with fast ions produce a high-energy tail in the distribution functions of impurity ions, and that close collisions between fusion-generated alpha particles give rise to a population of such particles with energies extending up to twice the birth energy. 44 refs

Time-dependent nonlinear Jaynes-Cummings dynamics of a trapped ion

Science.gov (United States)

Krumm, F.; Vogel, W.

2018-04-01

In quantum interaction problems with explicitly time-dependent interaction Hamiltonians, the time ordering plays a crucial role for describing the quantum evolution of the system under consideration. In such complex scenarios, exact solutions of the dynamics are rarely available. Here we study the nonlinear vibronic dynamics of a trapped ion, driven in the resolved sideband regime with some small frequency mismatch. By describing the pump field in a quantized manner, we are able to derive exact solutions for the dynamics of the system. This eventually allows us to provide analytical solutions for various types of time-dependent quantities. In particular, we study in some detail the electronic and the motional quantum dynamics of the ion, as well as the time evolution of the nonclassicality of the motional quantum state.

Dynamical coupling of electrons and ions in Xray-induced dynamics

International Nuclear Information System (INIS)

Saalmann, Ulf; Camacho, Abraham; Rost, Jan-Michael

2015-01-01

Photo-absorption from short and intense Xray pulses by a molecule or a cluster triggers a complicated electron and ion dynamics. Whereas the excitation process concerns largely core-shell electrons, there are various subsequent relaxation channels like electronic decays and ionic Coulomb explosion. We will discuss the interplay of those processes for molecular clusters and fullerenes. (paper)

Continuous desalting of refolded protein solution improves capturing in ion exchange chromatography: A seamless process.

Science.gov (United States)

Walch, Nicole; Jungbauer, Alois

2017-06-01

Truly continuous biomanufacturing processes enable an uninterrupted feed stream throughout the whole production without the need for holding tanks. We have utilized microporous anion and cation exchangers into which only salts, but not proteins, can penetrate into the pores for desalting of protein solutions, while diafiltration or dilution is usually employed for feed adjustments. Anion exchange and cation exchange chromatography columns were connected in series to remove both anions and cations. To increase operation performance, a continuous process was developed comprised of four columns. Continuous mode was achieved by staggered cycle operation, where one set of columns, consisting of one anion exchange and one cation exchange column, was loaded during the regeneration of the second set. Refolding, desalting and subsequent ion exchange capturing with a scFv as the model protein was demonstrated. The refolding solution was successfully desalted resulting in a consistent conductivity below 0.5 mS/cm from initial values of 10 to 11 mS/cm. With continuous operation process time could be reduced by 39% while productivity was increased to 163% compared to batch operation. Desalting of the protein solution resulted in up to 7-fold higher binding capacities in the subsequent ion exchange capture step with conventional protein binding resins. © 2017 The Authors. Biotechnology Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamic monitoring of transmembrane potential changes: a study of ion channels using an electrical double layer-gated FET biosensor.

Science.gov (United States)

Pulikkathodi, Anil Kumar; Sarangadharan, Indu; Chen, Yi-Hong; Lee, Geng-Yen; Chyi, Jen-Inn; Lee, Gwo-Bin; Wang, Yu-Lin

2018-03-27

In this research, we have designed, fabricated and characterized an electrical double layer (EDL)-gated AlGaN/GaN high electron mobility transistor (HEMT) biosensor array to study the transmembrane potential changes of cells. The sensor array platform is designed to detect and count circulating tumor cells (CTCs) of colorectal cancer (CRC) and investigate cellular bioelectric signals. Using the EDL FET biosensor platform, cellular responses can be studied in physiological salt concentrations, thereby eliminating complex automation. Upon investigation, we discovered that our sensor response follows the transmembrane potential changes of captured cells. Our whole cell sensor platform can be used to monitor the dynamic changes in the membrane potential of cells. The effects of continuously changing electrolyte ion concentrations and ion channel blocking using cadmium are investigated. This methodology has the potential to be used as an electrophysiological probe for studying ion channel gating and the interaction of biomolecules in cells. The sensor can also be a point-of-care diagnostic tool for rapid screening of diseases.

Beam-front dynamics and ion acceleration in drifting intense relativistic electron beams

International Nuclear Information System (INIS)

Alexander, K.F.; Hintze, W.

1976-01-01

Collective ion acceleration at the injection of a relativistic electron beam into a low-pressure gas or a plasma is discussed and its strong dependence on the beam-front dynamics is shown. A simple one-dimensional model taking explicitly into account the motion and ionizing action of the ions in the beam-front region is developed for the calculation of the beam drift velocity. The obtained pressure dependence is in good agreement with experimental data. The energy distribution is shown of the ions accelerated in the moving potential well of the space charge region. Scaling laws for the beam-front dynamics and ion acceleration are derived. (J.U.)

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

DEFF Research Database (Denmark)

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

2003-01-01

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

Dynamic Synchronous Capture Algorithm for an Electromagnetic Flowmeter.

Science.gov (United States)

Fanjiang, Yong-Yi; Lu, Shih-Wei

2017-04-10

This paper proposes a dynamic synchronous capture (DSC) algorithm to calculate the flow rate for an electromagnetic flowmeter. The characteristics of the DSC algorithm can accurately calculate the flow rate signal and efficiently convert an analog signal to upgrade the execution performance of a microcontroller unit (MCU). Furthermore, it can reduce interference from abnormal noise. It is extremely steady and independent of fluctuations in the flow measurement. Moreover, it can calculate the current flow rate signal immediately (m/s). The DSC algorithm can be applied to the current general MCU firmware platform without using DSP (Digital Signal Processing) or a high-speed and high-end MCU platform, and signal amplification by hardware reduces the demand for ADC accuracy, which reduces the cost.

Generation of monoenergetic ion beams via ionization dynamics (Conference Presentation)

Science.gov (United States)

Lin, Chen; Kim, I. Jong; Yu, Jinqing; Choi, Il Woo; Ma, Wenjun; Yan, Xueqing; Nam, Chang Hee

2017-05-01

The research on ion acceleration driven by high intensity laser pulse has attracted significant interests in recent decades due to the developments of laser technology. The intensive study of energetic ion bunches is particularly stimulated by wide applications in nuclear fusion, medical treatment, warm dense matter production and high energy density physics. However, to implement such compact accelerators, challenges are still existing in terms of beam quality and stability, especially in applications that require higher energy and narrow bandwidth spectra ion beams. We report on the acceleration of quasi-mono-energetic ion beams via ionization dynamics in the interaction of an intense laser pulse with a solid target. Using ionization dynamics model in 2D particle-in-cell (PIC) simulations, we found that high charge state contamination ions can only be ionized in the central spot area where the intensity of sheath field surpasses their ionization threshold. These ions automatically form a microstructure target with a width of few micron scale, which is conducive to generate mono-energetic beams. In the experiment of ultraintense (< 10^21 W/cm^2) laser pulses irradiating ultrathin targets each attracted with a contamination layer of nm-thickness, high quality < 100 MeV mono-energetic ion bunches are generated. The peak energy of the self-generated micro-structured target ions with respect to different contamination layer thickness is also examined This is relatively newfound respect, which is confirmed by the consistence between experiment data and the simulation results.

Heavy ion radiative capture. A study of the 12C(12C,γ) reaction using a large germanium detector array

International Nuclear Information System (INIS)

Jenkins, D.G.; Lister, C.J.; Carpenter, M.P.

2002-01-01

A new technique has been developed to investigate the little-explored phenomenon of heavy ion radiative capture. Employing a state-of-the-art germanium detector array (GAMMASPHERE) in a novel fashion as a sum energy calorimeter it is possible to separate the radiative capture channel from overwhelming competition from particle emission channels with exquisite sensitivity. By studying in detail the decay pathways and the intermediate states populated in the decay, it is possible to learn information relevant to the hypothesis of nuclear molecular states. (author)

Immersion autometallography: histochemical in situ capturing of zinc ions in catalytic zinc-sulfur nanocrystals.

Science.gov (United States)

Danscher, Gorm; Stoltenberg, Meredin; Bruhn, Mikkel; Søndergaard, Chris; Jensen, Dorete

2004-12-01

In the mid-1980s, two versions of Timm's original immersion sulfide silver method were published. The authors used immersion of tissue in a sulfide solution as opposed to Timm, who used immersion of tissue blocks in hydrogen sulfide-bubbled alcohol. The autometallography staining resulting from the "sulfide only immersion" was not particularly impressive, but the significance of this return to an old approach became obvious when Wenzel and co-workers presented their approach in connection with introduction by the Palmiter group of zinc transporter 3 (ZnT3). The Wenzel/Palmiter pictures are the first high-resolution, high-quality pictures taken from tissues in which free and loosely bound zinc ions have been captured in zinc-sulfur nanocrystals by immersion. The trick was to place formalin-fixed blocks of mouse brains in a solution containing 3% glutaraldehyde and 0.1% sodium sulfide, ingredients used for transcardial perfusion in the zinc-specific NeoTimm method. That the NeoTimm technique results in silver enhancement of zinc-sulfur nanocrystals has been proved by proton-induced X-ray multielement analyses (PIXE) and in vivo chelation with diethyldithiocarbamate (DEDTC). The aims of the present study were (a) to make the immersion-based capturing of zinc ions in zinc-sulfur nanocrystals work directly on sections and slices of fixed brain tissue, (b) to work out protocols that ensure zinc specificity and optimal quality of the staining, (c) to apply "immersion autometallography" (iZnSAMG) to other tissues that contain zinc-enriched (ZEN) cells, and (d) to make the immersion approach work on unfixed fresh tissue.

The effects of electron transfer on the energy loss of slow He2+, C2+, and C4+ ions penetrating a graphene fragment

International Nuclear Information System (INIS)

Mao, Fei; Zhang, Chao; Gao, Cong-Zhang; Dai, Jinxia; Zhang, Feng-Shou

2014-01-01

Electronic energy loss in the collision processes of slow ions with a graphene fragment is investigated by combining ab initio time-dependent density functional theory calculations for electrons with molecular dynamics simulations for ions in real time and real space. We study the electronic energy loss of slow He 2+ , C 2+ , and C 4+ ions penetrating the graphene fragment as a function of the ion velocity, and establish the velocity-proportional energy loss for low-charged ions down to 0.1 a.u. One mechanism clarified in the simulations for electron transfer is polarization capture, which is effective for bare ions at low velocities. The other one is resonance capture, by which the incident ion can capture electrons from the graphene fragment to its electron affinity levels, which have the same, or nearly the same, energy as those of the electron donor levels. The results demonstrate that the nonlinear behavior of energy loss of C 4+ is attributed to the large number of electrons captured by this multi-charged ion during the collision. (paper)

Relativistic quantum dynamics in strong fields: Photon emission from heavy, few-electron ions

International Nuclear Information System (INIS)

Fritzsche, S.; Stoehlker, T.

2005-03-01

Recent progress in the study of the photon emission from highly-charged heavy ions is reviewed. These investigations show that high-Z ions provide a unique tool for improving the understanding of the electron-electron and electron-photon interaction in the presence of strong fields. Apart from the bound-state transitions, which are accurately described in the framework of quantum electrodynamics, much information has been obtained also from the radiative capture of (quasi-) free electrons by high-Z ions. Many features in the observed spectra hereby confirm the inherently relativistic behavior of even the simplest compound quantum systems in nature. (orig.)

Toward Capturing Momentary Changes of Heart Rate Variability by a Dynamic Analysis Method.

Directory of Open Access Journals (Sweden)

Haoshi Zhang

Full Text Available The analysis of heart rate variability (HRV has been performed on long-term electrocardiography (ECG recordings (12~24 hours and short-term recordings (2~5 minutes, which may not capture momentary change of HRV. In this study, we present a new method to analyze the momentary HRV (mHRV. The ECG recordings were segmented into a series of overlapped HRV analysis windows with a window length of 5 minutes and different time increments. The performance of the proposed method in delineating the dynamics of momentary HRV measurement was evaluated with four commonly used time courses of HRV measures on both synthetic time series and real ECG recordings from human subjects and dogs. Our results showed that a smaller time increment could capture more dynamical information on transient changes. Considering a too short increment such as 10 s would cause the indented time courses of the four measures, a 1-min time increment (4-min overlapping was suggested in the analysis of mHRV in the study. ECG recordings from human subjects and dogs were used to further assess the effectiveness of the proposed method. The pilot study demonstrated that the proposed analysis of mHRV could provide more accurate assessment of the dynamical changes in cardiac activity than the conventional measures of HRV (without time overlapping. The proposed method may provide an efficient means in delineating the dynamics of momentary HRV and it would be worthy performing more investigations.

Lithium-ion battery capacity fading dynamics modelling for formulation optimization: A stochastic approach to accelerate the design process

International Nuclear Information System (INIS)

Tao, Laifa; Cheng, Yujie; Lu, Chen; Su, Yuzhuan; Chong, Jin; Jin, Haizu; Lin, Yongshou; Noktehdan, Azadeh

2017-01-01

Highlights: •The model is linked to known physicochemical degradation processes and material properties. •Aging dynamics of various battery formulations can be understood by the proposed model. •Large number of experiments will be reduced to accelerate the battery design process. •This approach can describe batteries under various operating conditions. •The proposed model is simple and easily implemented. -- Abstract: A five-state nonhomogeneous Markov chain model, which is an effective and promising way to accelerate the Li-ion battery design process by investigating the capacity fading dynamics of different formulations during the battery design phase, is reported. The parameters of this model are linked to known physicochemical degradation dynamics and material properties. Herein, the states and behaviors of the active materials in Li-ion batteries are modelled. To verify the efficiency of the proposed model, a dataset from approximately 3 years of cycling capacity fading experiments of various formulations using several different materials provided by Contemporary Amperex Technology Limited (CATL), as well as a NASA dataset, are employed. The capabilities of the proposed model for different amounts (50%, 70%, and 90%) of available experimental capacity data are tested and analyzed to assist with the final design determination for manufacturers. The average relative errors of life cycling prediction acquired from these tests are less than 2.4%, 0.8%, and 0.3%, even when only 50%, 70%, and 90% of the data, respectively, is available for different anode materials, electrolyte materials, and individual batteries. Furthermore, the variance is 0.518% when only 50% of the data are available; i.e., one can save at least 50% of the total experimental time and cost with an accuracy greater than 97% in the design phase, which demonstrates an effective and promising way to accelerate the Li-ion battery design process. The qualitative and quantitative analyses

Influence of surface oxidation on ion dynamics and capacitance in porous and nonporous carbon electrodes

Energy Technology Data Exchange (ETDEWEB)

Dyatkin, Boris [Drexel Univ., Philadelphia, PA (United States); Zhang, Yu [Vanderbilt Univ., Nashville, TN (United States); Mamontov, Eugene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kolesnikov, Alexander I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cheng, Yongqiang [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Meyer, III, Harry M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cummings, Peter T. [Vanderbilt Univ., Nashville, TN (United States); Gogotsi, Yury G. [Drexel Univ., Philadelphia, PA (United States)

2016-04-07

Here, we investigate the influence of surface chemistry and ion confinement on capacitance and electrosorption dynamics of room-temperature ionic liquids (RTILs) in supercapacitors. Using air oxidation and vacuum annealing, we produced defunctionalized and oxygen-rich surfaces of carbide-derived carbons (CDCs) and graphene nanoplatelets (GNPs). While oxidized surfaces of porous CDCs improve capacitance and rate handling abilities of ions, defunctionalized nonporous GNPs improve charge storage densities on planar electrodes. Quasi-elastic neutron scattering (QENS) and inelastic neutron scattering (INS) probed the structure, dynamics, and orientation of RTIL ions confined in divergently functionalized pores. Oxidized, ionophilic surfaces draw ions closer to pore surfaces and enhance potential-driven ion transport during electrosorption. Molecular dynamics (MD) simulations corroborated experimental data and demonstrated the significance of surface functional groups on ion orientations, accumulation densities, and capacitance.

Dynamics of an ion chain in a harmonic potential

International Nuclear Information System (INIS)

Morigi, Giovanna; Fishman, Shmuel

2004-01-01

Cold ions in anisotropic harmonic potentials can form ion chains of various sizes. Here, the density of ions is not uniform, and thus the eigenmodes are not phononic-like waves. We study chains of N>>1 ions and evaluate analytically the long-wavelength modes and the density of states in the short-wavelength limit. These results reproduce with good approximation the dynamics of chains consisting of dozens of ions. Moreover, they allow one to determine the critical transverse frequency required for the stability of the linear structure, which is found to be in agreement with results obtained by different theoretical methods [D. H. E. Dubin, Phys. Rev. Lett. 71, 2753 (1993)] and by numerical simulations [J. P. Schiffer, Phys. Rev. Lett. 70, 818 (1993)]. We introduce and explore the thermodynamic limit for the ion chain. The thermodynamic functions are found to exhibit deviations from extensivity

Structure and dynamics of highly charged heavy ions studied with the electron beam ion trap in Tokyo

International Nuclear Information System (INIS)

Nakamura, Nobuyuki; Hu, Zhimin; Watanabe, Hirofumi; Li, Yueming; Kato, Daiji; Currell, Fred J.; Tong Xiaomin; Watanabe, Tsutomu; Ohtani, Shunsuke

2011-01-01

In this paper, we present the structure and the dynamics of highly charged heavy ions studied through dielectronic recombination (DR) observations performed with the Tokyo electron beam ion trap. By measuring the energy dependence of the ion abundance ratio in the trap at equilibrium, we have observed DR processes for open shell systems very clearly. Remarkable relativistic effects due to the generalized Breit interaction have been clearly shown in DR for highly charged heavy ions. We also present the first result for the coincidence measurement of two photons emitted from a single DR event.

CONTRIBUTIONS OF INTRACELLULAR IONS TO Kv CHANNEL VOLTAGE SENSOR DYNAMICS.

Directory of Open Access Journals (Sweden)

Samuel eGoodchild

2012-06-01

Full Text Available Voltage sensing domains of Kv channels control ionic conductance through coupling of the movement of charged residues in the S4 segment to conformational changes at the cytoplasmic region of the pore domain, that allow K+ ions to flow. Conformational transitions within the voltage sensing domain caused by changes in the applied voltage across the membrane field are coupled to the conducting pore region and the gating of ionic conductance. However, several other factors not directly linked to the voltage dependent movement of charged residues within the voltage sensor impact the dynamics of the voltage sensor, such as inactivation, ionic conductance, intracellular ion identity and block of the channel by intracellular ligands. The effect of intracellular ions on voltage sensor dynamics is of importance in the interpretation of gating current measurements and the physiology of pore/voltage sensor coupling. There is a significant amount of variability in the reported kinetics of voltage sensor deactivation kinetics of Kv channels attributed to different mechanisms such as open state stabilization, immobilization and relaxation processes of the voltage sensor. Here we separate these factors and focus on the causal role that intracellular ions can play in allosterically modulating the dynamics of Kv voltage sensor deactivation kinetics. These considerations are of critical importance in understanding the molecular determinants of the complete channel gating cycle from activation to deactivation.

Dynamical limitations to heavy-ion fusion

International Nuclear Information System (INIS)

Back, B.B.

1983-01-01

In spite of the many attempts to synthesize superheavy elements in recent years, these efforts have not yet been successful. Recent improved theoretical models of heavy-ion fusion reactions suggest that the formation of super-heavy elements is hindered by the dynamics of the process. Several recent experiments lend support to these theories. The necessity of an excess radial velocity (extra push) over the Coulomb barrier in order to induce fusion is observed experimentally as predicted by the theory. So is a new reaction mechanism, called quasi-fission which tend to exhaust the part of the reaction cross section, which would otherwise lead to fusion. The present study shows that the angular distribution of fragments from quasi-fission processes are very sensitive to the occurrence of this reaction mechanism. A slight modification of one parameter in the theory demanded by the observation of quasi-fission for lighter projectiles via the angular distributions, has the consequence of posing even more-stringent limitations on heavy-ion-fusion reactions. This reduces even further the possibility for synthesizing and identifying superheavy elements in heavy-ion-fusion reactions

Differential Single-Capture Cross Sections for Fast Alpha–Helium Collisions

International Nuclear Information System (INIS)

Ghanbari-Adivi, Ebrahim; Ghavaminia, Hoda

2014-01-01

A four-body theoretical study of the single charge transfer process in collision of energetic alpha ions with helium atoms in their ground states is presented. The model utilizes the Coulomb–Born distorted wave approximation with correct boundary conditions to calculate the single-electron capture differential and integral cross sections. The influence of the dynamic and static electron correlations on the capture probability is investigated. The results of the calculations are compared with the recent experimental measurements for differential cross sections and with the other theoretical manipulations. The results for scattering at extreme forward angles are in good agreement with the experimental measurements, but in other scattering angles the agreement is poor. However, the present four-body results for integral cross sections are in excellent agreement with the experimental data. (author)

Anode plasma dynamics in an extraction applied-B ion diode: effects on divergence, ion species and parasitic load

International Nuclear Information System (INIS)

Greenly, J.B.; Appartaim, R.K.; Olson, J.C.

1996-01-01

Analysis of data from the LION (1.2 MV, 300 kA, 40 ns) extraction applied-B diode allows a number of inferences regarding the effect of anode plasma dynamics on ion beam divergence, ion species composition, and diode impedance and power coupling. The two dominant features of anode plasma dynamics observed on LION are (1) plasma expansion away from the solid anode surface and into the accelerating gap during the beam pulse, and (2) evolution of the composition of the plasma during the pulse. The data presented in this paper characterize the plasma expansion, and suggest a possible picture of the mechanism of the plasma dynamics that could produce these basic features. (J.U.). 2 figs., 5 refs

Anode plasma dynamics in an extraction applied-B ion diode: effects on divergence, ion species and parasitic load

Energy Technology Data Exchange (ETDEWEB)

Greenly, J B; Appartaim, R K; Olson, J C [Cornell Univ., Ithaca, NY (United States). Lab. of Plasma Studies

1997-12-31

Analysis of data from the LION (1.2 MV, 300 kA, 40 ns) extraction applied-B diode allows a number of inferences regarding the effect of anode plasma dynamics on ion beam divergence, ion species composition, and diode impedance and power coupling. The two dominant features of anode plasma dynamics observed on LION are (1) plasma expansion away from the solid anode surface and into the accelerating gap during the beam pulse, and (2) evolution of the composition of the plasma during the pulse. The data presented in this paper characterize the plasma expansion, and suggest a possible picture of the mechanism of the plasma dynamics that could produce these basic features. (J.U.). 2 figs., 5 refs.

Theoretical progress in studying the characteristic x-ray emission from heavy few-electron ions

International Nuclear Information System (INIS)

Surzhykov, Andrey; Stohlker, Thomas; Fritzsche, Stephan; Kabachnik, Nikolai M

2009-01-01

Recent theoretical progress in the study of the x-ray characteristic emission from highly-charged, few-electron ions is reviewed. These investigations show that the bound-state radiative transitions in high-Z ions provide a unique tool for better understanding the interplay between the structural and dynamical properties of heavy ions. In order to illustrate such an interplay, detailed calculations are presented for the K α1 decay of the helium-like uranium ions U 90+ following radiative electron capture, Coulomb excitation and dielectronic recombination processes.

Molecular dynamics studies of the ion beam induced crystallization in silicon

International Nuclear Information System (INIS)

Marques, L.A.; Caturla, M.J.; Huang, H.

1995-01-01

We have studied the ion bombardment induced amorphous-to-crystal transition in silicon using molecular dynamics techniques. The growth of small crystal seeds embedded in the amorphous phase has been monitored for several temperatures in order to get information on the effect of the thermal temperature increase introduced by the incoming ion. The role of ion-induced defects on the growth has been also studied

Design and Beam Dynamics Studies of a Multi-Ion Linac Injector for the JLEIC Ion Complex

Energy Technology Data Exchange (ETDEWEB)

Ostroumov, P. N.; Plastun, A. S.; Mustapha, B.; Conway, Z. A.

2016-01-01

The electron-ion collider (JLEIC) being proposed at JLab requires a new ion accelerator complex which includes a linac capable of delivering any ion beam from hydrogen to lead to the booster. We are currently developing a linac which consists of several ion sources, a normal conducting (NC) front end, up to 5 MeV/u, and a SC section for energies > 5 MeV/u. This design work is focused on the beam dynamics and electrodynamics studies performed to design efficient and cost-effective accelerating structures for both the NC and SC sections of the linac. Currently, we are considering two separate RFQs for the heavy-ion and light-ion beams including polarized beams, and different types of NC accelerating structures downstream of the RFQ. Quarter-wave and half-wave resonators can be effectively used in the SC section.

Ion colliders

Energy Technology Data Exchange (ETDEWEB)

Fischer, W.

2011-12-01

Ion colliders are research tools for high-energy nuclear physics, and are used to test the theory of Quantum Chromo Dynamics (QCD). The collisions of fully stripped high-energy ions create matter of a temperature and density that existed only microseconds after the Big Bang. Ion colliders can reach higher densities and temperatures than fixed target experiments although at a much lower luminosity. The first ion collider was the CERN Intersecting Storage Ring (ISR), which collided light ions [77Asb1, 81Bou1]. The BNL Relativistic Heavy Ion Collider (RHIC) is in operation since 2000 and has collided a number of species at numerous energies. The CERN Large Hadron Collider (LHC) started the heavy ion program in 2010. Table 1 shows all previous and the currently planned running modes for ISR, RHIC, and LHC. All three machines also collide protons, which are spin-polarized in RHIC. Ion colliders differ from proton or antiproton colliders in a number of ways: the preparation of the ions in the source and the pre-injector chain is limited by other effects than for protons; frequent changes in the collision energy and particle species, including asymmetric species, are typical; and the interaction of ions with each other and accelerator components is different from protons, which has implications for collision products, collimation, the beam dump, and intercepting instrumentation devices such a profile monitors. In the preparation for the collider use the charge state Z of the ions is successively increased to minimize the effects of space charge, intrabeam scattering (IBS), charge change effects (electron capture and stripping), and ion-impact desorption after beam loss. Low charge states reduce space charge, intrabeam scattering, and electron capture effects. High charge states reduce electron stripping, and make bending and acceleration more effective. Electron stripping at higher energies is generally more efficient. Table 2 shows the charge states and energies in the

Ion colliders

International Nuclear Information System (INIS)

Fischer, W.

2010-01-01

Ion colliders are research tools for high-energy nuclear physics, and are used to test the theory of Quantum Chromo Dynamics (QCD). The collisions of fully stripped high-energy ions create matter of a temperature and density that existed only microseconds after the Big Bang. Ion colliders can reach higher densities and temperatures than fixed target experiments although at a much lower luminosity. The first ion collider was the CERN Intersecting Storage Ring (ISR), which collided light ions (77Asb1, 81Bou1). The BNL Relativistic Heavy Ion Collider (RHIC) is in operation since 2000 and has collided a number of species at numerous energies. The CERN Large Hadron Collider (LHC) started the heavy ion program in 2010. Table 1 shows all previous and the currently planned running modes for ISR, RHIC, and LHC. All three machines also collide protons, which are spin-polarized in RHIC. Ion colliders differ from proton or antiproton colliders in a number of ways: the preparation of the ions in the source and the pre-injector chain is limited by other effects than for protons; frequent changes in the collision energy and particle species, including asymmetric species, are typical; and the interaction of ions with each other and accelerator components is different from protons, which has implications for collision products, collimation, the beam dump, and intercepting instrumentation devices such a profile monitors. In the preparation for the collider use the charge state Z of the ions is successively increased to minimize the effects of space charge, intrabeam scattering (IBS), charge change effects (electron capture and stripping), and ion-impact desorption after beam loss. Low charge states reduce space charge, intrabeam scattering, and electron capture effects. High charge states reduce electron stripping, and make bending and acceleration more effective. Electron stripping at higher energies is generally more efficient. Table 2 shows the charge states and energies in the

Anion capture and sensing with cationic boranes: on the synergy of Coulombic effects and onium ion-centred Lewis acidity.

Science.gov (United States)

Zhao, Haiyan; Leamer, Lauren A; Gabbaï, François P

2013-06-21

Stimulated by the growing importance and recognized toxicity of anions such as fluoride, cyanide and azides, we have, in the past few years, developed a family of Lewis acidic triarylboranes that can be used for the complexation of these anions in organic and protic solvents, including water. A central aspect of our approach lies in the decoration of the boranes with peripheral ammonium, phosphonium, sulfonium stibonium or telluronium groups. The presence of these cationic groups provides a Coulombic drive for the capture of the anion, leading to boranes that can be used in aqueous solutions where anion hydration and/or protonation are usually competitive. The anion affinity of these boranes can be markedly enhanced by narrowing the separation between the anion binding site (i.e. the boron atom) and the onium ion. In such systems, the latent Lewis acidity of the onium ion also plays a role as manifested by the formation of B-X→E (E = P, S, Sb, or Te; X = F, CN or N3) chelate motifs that provide additional stability to the resulting complexes. These effects, which are maximum in stibonium and telluronium boranes, show that the Lewis acidity of heavy onium ions can be exploited for anion coordination and capture. The significance of these advances is illustrated by the development of applications in anion sensing, fluorination chemistry and (18)F radiolabeling for positron emission tomography.

Role of the cluster structure of {sup 7}Li in the dynamics of fragment capture

Energy Technology Data Exchange (ETDEWEB)

Shrivastava, A., E-mail: aradhana@barc.gov.in [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Navin, A. [GANIL, CEA/DSM - CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); Diaz-Torres, A. [ECT, Villa Tambosi, I-38123 Villazzano, Trento (Italy); Nanal, V. [DNAP, Tata Institute of Fundamental Research, Mumbai 400005 (India); Ramachandran, K. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Rejmund, M. [GANIL, CEA/DSM - CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); Bhattacharyya, S. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India); Chatterjee, A.; Kailas, S. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Lemasson, A. [GANIL, CEA/DSM - CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); Palit, R. [DNAP, Tata Institute of Fundamental Research, Mumbai 400005 (India); Parkar, V.V. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Pillay, R.G. [DNAP, Tata Institute of Fundamental Research, Mumbai 400005 (India); Rout, P.C. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sawant, Y. [DNAP, Tata Institute of Fundamental Research, Mumbai 400005 (India)

2013-01-08

Exclusive measurements of prompt {gamma}-rays from the heavy-residues with various light charged particles in the {sup 7}Li + {sup 198}Pt system, at an energy near the Coulomb barrier (E/V{sub b}{approx}1.6) are reported. Recent dynamic classical trajectory calculations, constrained by the measured fusion, {alpha}- and t-capture cross-sections have been used to explain the excitation energy dependence of the residue cross-sections. These calculations distinctly illustrate a two-step process, breakup followed by fusion, in case of the capture of t and {alpha} clusters; whereas for {sup 6}He+p and {sup 5}He+d configurations, massive transfer is inferred to be the dominant mechanism. The present work clearly demonstrates the role played by the cluster structures of {sup 7}Li in understanding the reaction dynamics at energies around the Coulomb barrier.

Surface modification of M50 steel by dual-ion-beam dynamic mixing

International Nuclear Information System (INIS)

Kuang Yuanzhu; Jan Jun; Qin Ouyang

1994-01-01

TaN films have many attractive characteristics, and so have been used for electronic and mechanical applications. There are many methods used for deposition of TaN films. Recently, the ion-beam dynamic mixing method has been used for thin film deposition and materials modification. In order to obtain high performance, stoichiometric composition and good adhesion we have deposited TaN films by a dual-ion-beam dynamic mixing method. This paper introduces the deposition and properties of TaN films on M50 steel by dual-ion-beam dynamic mixing. The microstructure of films was analysed by X-ray diffraction and Auger electron spectroscopy (AES). The microhardness, resistance to wear and erosion of these films were determined. The results showed that (1) the TaN films were successfully deposited on M50 steel by this method, (2) the performance, resistance to wear and erosion of M50 steel were improved by ion-beam-mixing deposition of the TaN thin films, (3) AES showed there was a mixed layer on the film interface, (4) the microhardness of the thin film depends on microstructure and thickness and (5) the microstructure and quality of the films depends on the deposition conditions, so it is important to select the proper operational parameters of ion sources. ((orig.))

Kinetic modeling of particle dynamics in H− negative ion sources (invited)

International Nuclear Information System (INIS)

Hatayama, A.; Shibata, T.; Nishioka, S.; Ohta, M.; Yasumoto, M.; Nishida, K.; Yamamoto, T.; Miyamoto, K.; Fukano, A.; Mizuno, T.

2014-01-01

Progress in the kinetic modeling of particle dynamics in H − negative ion source plasmas and their comparisons with experiments are reviewed, and discussed with some new results. Main focus is placed on the following two topics, which are important for the research and development of large negative ion sources and high power H − ion beams: (i) Effects of non-equilibrium features of EEDF (electron energy distribution function) on H − production, and (ii) extraction physics of H − ions and beam optics

Mode coupling theory analysis of electrolyte solutions: Time dependent diffusion, intermediate scattering function, and ion solvation dynamics.

Science.gov (United States)

Roy, Susmita; Yashonath, Subramanian; Bagchi, Biman

2015-03-28

A self-consistent mode coupling theory (MCT) with microscopic inputs of equilibrium pair correlation functions is developed to analyze electrolyte dynamics. We apply the theory to calculate concentration dependence of (i) time dependent ion diffusion, (ii) intermediate scattering function of the constituent ions, and (iii) ion solvation dynamics in electrolyte solution. Brownian dynamics with implicit water molecules and molecular dynamics method with explicit water are used to check the theoretical predictions. The time dependence of ionic self-diffusion coefficient and the corresponding intermediate scattering function evaluated from our MCT approach show quantitative agreement with early experimental and present Brownian dynamic simulation results. With increasing concentration, the dispersion of electrolyte friction is found to occur at increasingly higher frequency, due to the faster relaxation of the ion atmosphere. The wave number dependence of intermediate scattering function, F(k, t), exhibits markedly different relaxation dynamics at different length scales. At small wave numbers, we find the emergence of a step-like relaxation, indicating the presence of both fast and slow time scales in the system. Such behavior allows an intriguing analogy with temperature dependent relaxation dynamics of supercooled liquids. We find that solvation dynamics of a tagged ion exhibits a power law decay at long times-the decay can also be fitted to a stretched exponential form. The emergence of the power law in solvation dynamics has been tested by carrying out long Brownian dynamics simulations with varying ionic concentrations. The solvation time correlation and ion-ion intermediate scattering function indeed exhibit highly interesting, non-trivial dynamical behavior at intermediate to longer times that require further experimental and theoretical studies.

Study of the interaction of potassium ion channel protein with micelle by molecular dynamics simulation

Science.gov (United States)

Shantappa, Anil; Talukdar, Keka

2018-04-01

Ion channels are proteins forming pore inside the body of all living organisms. This potassium ion channel known as KcsA channel and it is found in the each cell and nervous system. Flow of various ions is regulated by the function of the ion channels. The nerve ion channel protein with protein data bank entry 1BL8, which is basically an ion channel protein in Streptomyces Lividans and which is taken up to form micelle-protein system and the system is analyzed by using molecular dynamics simulation. Firstly, ion channel pore is engineered by CHARMM potential and then Micelle-protein system is subjected to molecular dynamics simulation. For some specific micelle concentration, the protein unfolding is observed.

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

Science.gov (United States)

Ki, Dae-Han; Jung, Young-Dae

2012-09-07

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

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

International Nuclear Information System (INIS)

Ki, Dae-Han; Jung, Young-Dae

2012-01-01

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

Interactions of heavy ions with biomolecules: a dynamical microscopic approach

International Nuclear Information System (INIS)

Zhang Fengshou; Beijing Radiation Center, Beijing; National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou

2006-01-01

The status of studying biology system therapy with X-rays, γ-rays, neutron, proton, and heavy ions is reviewed. The depth dose profile, called Bragg profile, makes heavy ion an ideal tool for radiotherapy. The physical process of therapy with heavy ions is analyzed and a 3-step interaction processes of heavy ions with biomolecules is proposed, that is, nuclear fragmentation in nuclear interaction, electron excitation in Coulomb interaction, and the biomolecules relaxation in surroundings, finally leads to a new structure of biomolecule. Since this physical process is the base of the following chemical process and biological process, a dynamical microscopic approach is strongly demanded to be built. (authors)

Porous solid ion exchange wafer for immobilizing biomolecules

Science.gov (United States)

Arora, Michelle B.; Hestekin, Jamie A.; Lin, YuPo J.; St. Martin, Edward J.; Snyder, Seth W.

2007-12-11

A porous solid ion exchange wafer having a combination of a biomolecule capture-resin and an ion-exchange resin forming a charged capture resin within said wafer. Also disclosed is a porous solid ion exchange wafer having a combination of a biomolecule capture-resin and an ion-exchange resin forming a charged capture resin within said wafer containing a biomolecule with a tag. A separate bioreactor is also disclosed incorporating the wafer described above.

Memory-induced nonlinear dynamics of excitation in cardiac diseases.

Science.gov (United States)

Landaw, Julian; Qu, Zhilin

2018-04-01

Excitable cells, such as cardiac myocytes, exhibit short-term memory, i.e., the state of the cell depends on its history of excitation. Memory can originate from slow recovery of membrane ion channels or from accumulation of intracellular ion concentrations, such as calcium ion or sodium ion concentration accumulation. Here we examine the effects of memory on excitation dynamics in cardiac myocytes under two diseased conditions, early repolarization and reduced repolarization reserve, each with memory from two different sources: slow recovery of a potassium ion channel and slow accumulation of the intracellular calcium ion concentration. We first carry out computer simulations of action potential models described by differential equations to demonstrate complex excitation dynamics, such as chaos. We then develop iterated map models that incorporate memory, which accurately capture the complex excitation dynamics and bifurcations of the action potential models. Finally, we carry out theoretical analyses of the iterated map models to reveal the underlying mechanisms of memory-induced nonlinear dynamics. Our study demonstrates that the memory effect can be unmasked or greatly exacerbated under certain diseased conditions, which promotes complex excitation dynamics, such as chaos. The iterated map models reveal that memory converts a monotonic iterated map function into a nonmonotonic one to promote the bifurcations leading to high periodicity and chaos.

Solvation of ions in the gas-phase: a molecular dynamics simulation

Science.gov (United States)

Cabarcos, Orlando M.; Lisy, James M.

1996-07-01

Molecular dynamics simulations have been performed on the collision between a cesium ion and a cluster of twenty methanol molecules. This process, generating a solvated ion, was studied over a range (1 to 25 eV) of eight collision energies. Preliminary analysis of this gas phase solvation has included the distribution of final ion cluster sizes, fragmentation patterns, solvation timescales and energetics. Two distinct patterns have emerged: a ballistic penetration of the neutral cluster at the higher collision energies and an evaporative evolution of the cluster ion at lower collision energies.

A Variety of Activation Methods Employed in 'Activated-Ion' Electron Capture Dissociation Mass Spectrometry: A Test against Bovine Ubiquitin 7+ Ions

International Nuclear Information System (INIS)

Oh, Han Bin; McLafferty, Fred W.

2006-01-01

Fragmentation efficiencies of various 'activated-ion' electron capture dissociation (AI-ECD) methods are compared for a model system of bovine ubiquitin 7+ cations. In AI-ECD studies, sufficient internal energy was given to protein cations prior to ECD application using IR laser radiation, collisions, blackbody radiation, or in-beam collisions, in turn. The added energy was utilized in increasing the population of the precursor ions with less intra-molecular noncovalent bonds or enhancing thermal fluctuations of the protein cations. Removal of noncovalent bonds resulted in extended structures, which are ECD friendly. Under their best conditions, a variety of activation methods showed a similar effectiveness in ECD fragmentation. In terms of the number of fragmented inter-residue bonds, IR laser/blackbody infrared radiation and 'in-beam' activation were almost equally efficient with ∼70% sequence coverage, while collisions were less productive. In particular, 'in-beam' activation showed an excellent effectiveness in characterizing a pre-fractionated single kind of protein species. However, its inherent procedure did not allow for isolation of the protein cations of interest

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

International Nuclear Information System (INIS)

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

2003-01-01

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

Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions

Energy Technology Data Exchange (ETDEWEB)

Bradforth, S.E.

1992-11-01

The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound [yields] bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN[sup [minus

Fast-ion dynamics in the TEXTOR tokamak measured by collective Thomson scattering

DEFF Research Database (Denmark)

Bindslev, H.; Nielsen, S.K.; Porte, L.

2006-01-01

Here we present the first measurements by collective Thomson scattering of the evolution of fast-ion populations in a magnetically confined fusion plasma. 150 kW and 110 Ghz radiation from a gyrotron were scattered in the TEXTOR tokamak plasma with energetic ions generated by neutral beam injection...... and ion cyclotron resonance heating. The temporal behavior of the spatially resolved fast-ion velocity distribution is inferred from the received scattered radiation. The fast-ion dynamics at sawteeth and the slowdown after switch off of auxiliary heating is resolved in time. The latter is shown...

Collisionally induced stochastic dynamics of fast ions in solids

International Nuclear Information System (INIS)

Burgdoerfer, J.

1989-01-01

Recent developments in the theory of excited state formation in collisions of fast highly charged ions with solids are reviewed. We discuss a classical transport theory employing Monte-Carlo sampling of solutions of a microscopic Langevin equation. Dynamical screening by the dielectric medium as well as multiple collisions are incorporated through the drift and stochastic forces in the Langevin equation. The close relationship between the extrinsically stochastic dynamics described by the Langevin and the intrinsic stochasticity in chaotic nonlinear dynamical systems is stressed. Comparison with experimental data and possible modification by quantum corrections are discussed. 49 refs., 11 figs

Dynamic sheath studies in plasma source ion implantation

International Nuclear Information System (INIS)

Schever, J.T.; Shamim, M.; Conrad, J.R.

1990-01-01

Plasma Source Ion Implantation (PSII) is a non-line-of-sight method for materials processing in which a target is immersed in a plasma and pulse biased to a high negative voltage (∼ 50 kV). A model of the dynamic sheath which forms under these conditions has been developed and applied to planar, cylindrical and spherical geometries. This model assumes that the transient sheath obeys the Child-Langmuir law for space charge limited emission at each instant during the propagation. Ions uncovered by the propagating sheath edge supply the space charge limited current. This yields an equation relating sheath edge velocity to position, which can be integrated to obtain the sheath edge position as a function of time. The same procedure used in cylindrical and spherical geometry results in a similar equation which must be integrated numerically. Comparison of results of experimental measurements, our model and simulation will be presented for the dynamic sheath edge position and target current waveform. Measurements of implanted dose uniformity of wedge shaped targets are also presented

A study of trapped ion dynamics by photon-correlation and pulse-probe techniques

International Nuclear Information System (INIS)

Rink, J.; Dholakia, K.; Zs, G.; Horvath, K.; Hernandez-Pozos, J. L.; Power, W.; Segal, D. M.; Thompson, R. C.; Walker, T.

1995-01-01

We demonstrate non-evasive methods for observing ion and ion cloud oscillation frequencies in a quadrupole ion trap. These trap resonances are measured for small clouds using a photon correlation technique. For large clouds the rotation frequency can be detected with the help of an additional pulsed probe laser. We show applications of the photon correlation method such as estimating the dynamic properties of a combined trap and detecting ion crystals

Transient dynamics in cavity electromagnetically induced transparency with ion Coulomb crystals

Science.gov (United States)

Albert, Magnus; Dantan, Aurélien; Drewsen, Michael

2018-03-01

We experimentally investigate the transient dynamics of an optical cavity field interacting with large ion Coulomb crystals in a situation of electromagnetically induced transparency (EIT). EIT is achieved by injecting a probe field at the single photon level and a more intense control field with opposite circular polarization into the same mode of an optical cavity to couple Zeeman substates of a metastable level in ? ions. The EIT interaction dynamics are investigated both in the frequency-domain - by measuring the probe field steady state reflectivity spectrum - and in the time-domain - by measuring the progressive buildup of transparency. The experimental results are observed to be in excellent agreement with theoretical predictions taking into account the inhomogeneity of the control field in the interaction volume, and confirm the high degree of control on light-matter interaction that can be achieved with ion Coulomb crystals in optical cavities.

Statistical estimate of factors influence on sorption of Mo(Ⅵ) ions by tin hydroxide in dynamic conditions

International Nuclear Information System (INIS)

Parshutkin, V.V.; Granovskiy, Yu.V.; Prozorovskaya, Z.N.

1986-01-01

Present work is devoted to statistical estimate of factors influence on sorption of Mo(Ⅵ) ions by tin hydroxide in dynamic conditions. The influence of different factors on the process of sorption of Co(Ⅵ) ions by cryo-granular tin hydroxide in dynamic conditions is studied and optimal conditions of their extraction from aqueous solutions are considered. It is defined that factors significant affect the sorption process in dynamic conditions are: concentration of Mo(Ⅵ) ions in solution; the mass of sorbent; the rate of transmission of solution through the layer of sorbent; concentration of SO 4 2- ions in solution.

A new gamma-ray diagnostic for energetic ion distributions - The Compton tail on the neutron capture line

International Nuclear Information System (INIS)

Vestrand, W.T.

1990-01-01

This paper presents a new radiation diagnostic for assaying the energy spectrum and the angular distribution of energetic ions incident on thick hydrogen-rich thermal targets. This diagnostic compares the number of emergent photons in the narrow neutron capture line at 2.223 MeV to the number of Compton scattered photons that form a low-energy tail on the line. It is shown that the relative strength of the tail can be used as a measure of the hardness of the incident ion-energy spectrum. Application of this diagnostic to solar flare conditions is the main thrust of the work presented here. It is examined how the strength of the Compton tail varies with flare viewing angle and the angular distribution of the flare-accelerated particles. Application to compact X-ray binary systems is also briefly discussed. 39 refs

Recoil ion spectroscopy with heavy ions

International Nuclear Information System (INIS)

Beyer, H.F.; Mann, R.

1984-01-01

This chapter examines the production of very high charge state ions in single ion-atom collisions. Topics considered include some aspects of highly ionized atoms, experimental approaches, the production of highly charged target ions (monoatomic targets, recoil energy distribution, molecular fragmentation, outer-shell rearrangement, lifetime measurements, a comparison of projectile-, target-, and plasma-ion stripping), and secondary collision experiments (selective electron capture, potential applications). The heavy-ion beams for the described experiments were provided by accelerators such as tandem Van de Graaff facility and the UNILAC

The Crossed-Beam Scattering Method in Studies of Ion-Molecule Reaction Dynamics

Czech Academy of Sciences Publication Activity Database

Herman, Zdeněk

2001-01-01

Roč. 212, - (2001), s. 413-443 ISSN 1387-3806 R&D Projects: GA ČR GA203/00/0632 Institutional research plan: CEZ:AV0Z4040901 Keywords : ion-molecule reaction dynamics * ion scattering * experimental methods Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.176, year: 2001

Quantifying microstructural dynamics and electrochemical activity of graphite and silicon-graphite lithium ion battery anodes

Science.gov (United States)

Pietsch, Patrick; Westhoff, Daniel; Feinauer, Julian; Eller, Jens; Marone, Federica; Stampanoni, Marco; Schmidt, Volker; Wood, Vanessa

2016-09-01

Despite numerous studies presenting advances in tomographic imaging and analysis of lithium ion batteries, graphite-based anodes have received little attention. Weak X-ray attenuation of graphite and, as a result, poor contrast between graphite and the other carbon-based components in an electrode pore space renders data analysis challenging. Here we demonstrate operando tomography of weakly attenuating electrodes during electrochemical (de)lithiation. We use propagation-based phase contrast tomography to facilitate the differentiation between weakly attenuating materials and apply digital volume correlation to capture the dynamics of the electrodes during operation. After validating that we can quantify the local electrochemical activity and microstructural changes throughout graphite electrodes, we apply our technique to graphite-silicon composite electrodes. We show that microstructural changes that occur during (de)lithiation of a pure graphite electrode are of the same order of magnitude as spatial inhomogeneities within it, while strain in composite electrodes is locally pronounced and introduces significant microstructural changes.

Dipole-Guided Electron Capture Causes Abnormal Dissociations of Phosphorylated Pentapeptides

DEFF Research Database (Denmark)

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

2011-01-01

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

Dynamics from seconds to hours in Hodgkin-Huxley model with time-dependent ion concentrations and buffer reservoirs.

Directory of Open Access Journals (Sweden)

Niklas Hübel

2014-12-01

Full Text Available The classical Hodgkin-Huxley (HH model neglects the time-dependence of ion concentrations in spiking dynamics. The dynamics is therefore limited to a time scale of milliseconds, which is determined by the membrane capacitance multiplied by the resistance of the ion channels, and by the gating time constants. We study slow dynamics in an extended HH framework that includes time-dependent ion concentrations, pumps, and buffers. Fluxes across the neuronal membrane change intra- and extracellular ion concentrations, whereby the latter can also change through contact to reservoirs in the surroundings. Ion gain and loss of the system is identified as a bifurcation parameter whose essential importance was not realized in earlier studies. Our systematic study of the bifurcation structure and thus the phase space structure helps to understand activation and inhibition of a new excitability in ion homeostasis which emerges in such extended models. Also modulatory mechanisms that regulate the spiking rate can be explained by bifurcations. The dynamics on three distinct slow times scales is determined by the cell volume-to-surface-area ratio and the membrane permeability (seconds, the buffer time constants (tens of seconds, and the slower backward buffering (minutes to hours. The modulatory dynamics and the newly emerging excitable dynamics corresponds to pathological conditions observed in epileptiform burst activity, and spreading depression in migraine aura and stroke, respectively.

Dynamics from seconds to hours in Hodgkin-Huxley model with time-dependent ion concentrations and buffer reservoirs.

Science.gov (United States)

Hübel, Niklas; Dahlem, Markus A

2014-12-01

The classical Hodgkin-Huxley (HH) model neglects the time-dependence of ion concentrations in spiking dynamics. The dynamics is therefore limited to a time scale of milliseconds, which is determined by the membrane capacitance multiplied by the resistance of the ion channels, and by the gating time constants. We study slow dynamics in an extended HH framework that includes time-dependent ion concentrations, pumps, and buffers. Fluxes across the neuronal membrane change intra- and extracellular ion concentrations, whereby the latter can also change through contact to reservoirs in the surroundings. Ion gain and loss of the system is identified as a bifurcation parameter whose essential importance was not realized in earlier studies. Our systematic study of the bifurcation structure and thus the phase space structure helps to understand activation and inhibition of a new excitability in ion homeostasis which emerges in such extended models. Also modulatory mechanisms that regulate the spiking rate can be explained by bifurcations. The dynamics on three distinct slow times scales is determined by the cell volume-to-surface-area ratio and the membrane permeability (seconds), the buffer time constants (tens of seconds), and the slower backward buffering (minutes to hours). The modulatory dynamics and the newly emerging excitable dynamics corresponds to pathological conditions observed in epileptiform burst activity, and spreading depression in migraine aura and stroke, respectively.

Measuring radiation damage dynamics by pulsed ion beam irradiation: 2016 project annual report

Energy Technology Data Exchange (ETDEWEB)

Kucheyev, Sergei O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-01-04

The major goal of this project is to develop and demonstrate a novel experimental approach to access the dynamic regime of radiation damage formation in nuclear materials. In particular, the project exploits a pulsed-ion-beam method in order to gain insight into defect interaction dynamics by measuring effective defect interaction time constants and defect diffusion lengths. For Year 3, this project had the following two major milestones: (i) the demonstration of the measurement of thermally activated defect-interaction processes by pulsed ion beam techniques and (ii) the demonstration of alternative characterization techniques to study defect dynamics. As we describe below, both of these milestones have been met.

Loss pattern of Pb ions with charge changing processes in the LEIR ring

CERN Document Server

Pasternak, J

2004-01-01

Avalanche like pressure rise and an associated decrease of the beam lifetime, caused by (i) beam loss due to charge exchange interactions with rest gas molecules and (ii) ion impact induced outgassing, is a potential limitation for heavy ion accelerators. The vacuum system of the LEIR ring has to be upgraded carefully to avoid that these phenomena prevent the machine from reaching design performance. The loss pattern of Pb ions having captured an electron presented in this report allows to estimate whether the low dynamic pressure needed for LEIR is reachable. Efficient interception of lost ions with low beam loss induced outgassing absorber blocks, installed at appropriate locations is promising.

Atom capture and loss in ion molecule collisions

International Nuclear Information System (INIS)

Breinig, M.; Lasley, S.E.; Gaither, C.C. III.

1985-01-01

Progress is reported in measuring the energy and angular distribution of protons emerging with velocity close to the beam velocity from the target region when Ar + beams collide with a CH 4 target and ArH + beams collide with a He target at asymptotically high speeds. The protons result from the transfer of a target constituent to the projectile (atom capture) or from the dissociation of the projectile molecule in the collision (atom loss). For atom capture processes the Thomas peak is clearly observed. 10 refs., 3 figs

Multiaperture ion beam extraction from gas-dynamic electron cyclotron resonance source of multicharged ions

International Nuclear Information System (INIS)

Sidorov, A.; Dorf, M.; Zorin, V.; Bokhanov, A.; Izotov, I.; Razin, S.; Skalyga, V.; Rossbach, J.; Spaedtke, P.; Balabaev, A.

2008-01-01

Electron cyclotron resonance ion source with quasi-gas-dynamic regime of plasma confinement (ReGIS), constructed at the Institute of Applied Physics, Russia, provides opportunities for extracting intense and high-brightness multicharged ion beams. Despite the short plasma lifetime in a magnetic trap of a ReGIS, the degree of multiple ionization may be significantly enhanced by the increase in power and frequency of the applied microwave radiation. The present work is focused on studying the intense beam quality of this source by the pepper-pot method. A single beamlet emittance measured by the pepper-pot method was found to be ∼70 π mm mrad, and the total extracted beam current obtained at 14 kV extraction voltage was ∼25 mA. The results of the numerical simulations of ion beam extraction are found to be in good agreement with experimental data

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

International Nuclear Information System (INIS)

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

1978-01-01

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

Dynamics of ions in the selectivity filter of the KcsA channel: Towards a coupled Brownian particle description

OpenAIRE

Cosseddu, Salvatore M.; Khovanov, Igor A.; Allen, Michael P.; Rodger, P. M.; Luchinsky, Dmitry G.; McClintock, Peter V. E.

2013-01-01

The statistical and dynamical properties of ions in the selectivity filter of the KcsA ion channel are considered on the basis of molecular dynamics (MD) simulations of the KcsA protein embedded in a lipid membrane surrounded by an ionic solution. A new approach to the derivation of a Brownian dynamics (BD) model of ion permeation through the filter is discussed, based on unbiased MD simulations. It is shown that depending on additional assumptions, ion’s dynamics can be described either by u...

Discrete time population dynamics of a two-stage species with recruitment and capture

International Nuclear Information System (INIS)

Ladino, Lilia M.; Mammana, Cristiana; Michetti, Elisabetta; Valverde, Jose C.

2016-01-01

This work models and analyzes the dynamics of a two-stage species with recruitment and capture factors. It arises from the discretization of a previous model developed by Ladino and Valverde (2013), which represents a progress in the knowledge of the dynamics of exploited populations. Although the methods used here are related to the study of discrete-time systems and are different from those related to continuous version, the results are similar in both the discrete and the continuous case what confirm the skill in the selection of the factors to design the model. Unlike for the continuous-time case, for the discrete-time one some (non-negative) parametric constraints are derived from the biological significance of the model and become fundamental for the proofs of such results. Finally, numerical simulations show different scenarios of dynamics related to the analytical results which confirm the validity of the model.

Ion Selectivity Mechanism in a Bacterial Pentameric Ligand-Gated Ion Channel

International Nuclear Information System (INIS)

Wang, Hailong; Cheng, Xiaolin

2011-01-01

The proton-gated ion channel from Gloeobacter violaceus (GLIC) is a prokaryotic homolog of the eukaryotic nicotinic acetylcholine receptor (nAChR) that responds to the binding of neurotransmitter acetylcholine and mediates fast signal transmission. Recent emergence of a high resolution crystal structure of GLIC captured in a potentially open state allowed detailed, atomic-level insight into ion conduction and selectivity mechanisms in these channels. Herein, we have examined the barriers to ion conduction and origins of ion selectivity in the GLIC channel by the construction of potential of mean force (PMF) profiles for sodium and chloride ions inside the transmembrane region. Our calculations reveal that the GLIC channel is open for a sodium ion to transport, but presents a ∼10 kcal/mol free energy barrier for a chloride ion, which arises primarily from the unfavorable interactions with a ring of negatively charged glutamate residues (E-2) at the intracellular end and a ring of hydrophobic residues (I9) in the middle of the transmembrane domain. Our collective findings further suggest that the charge selection mechanism can, to a large extent, be attributed to the narrow intracellular end and a ring of glutamate residues in this position their strong negative electrostatics and ability to bind cations. By contrast, E19 at the extracellular entrance only plays a minor role in ion selectivity of GLIC. In addition to electrostatics, both ion hydration and protein dynamics are found to be crucial for ion conduction as well, which explains why a chloride ion experiences a much greater barrier than a sodium ion in the hydrophobic region of the pore.

The role of Frenkel defect diffusion in dynamic annealing in ion-irradiated Si

Energy Technology Data Exchange (ETDEWEB)

Wallace, J. B.; Aji, L. B. Bayu; Martin, A. A.; Shin, S. J.; Shao, L.; Kucheyev, S. O.

2017-01-06

The formation of stable radiation damage in crystalline solids often proceeds via complex dynamic annealing processes, involving migration and interaction of ballistically-generated point defects. The dominant dynamic annealing processes, however, remain unknown even for crystalline Si. Here, we use a pulsed ion beam method to study defect dynamics in Si bombarded in the temperature range from -20 to 140 °C with 500 keV Ar ions. Results reveal a defect relaxation time constant of ~10–0.2 ms, which decreases monotonically with increasing temperature. The dynamic annealing rate shows an Arrhenius dependence with two well-defined activation energies of 73 ± 5 meV and 420 ± 10 meV, below and above 60 °C, respectively. Rate theory modeling, bench-marked against this data, suggests a crucial role of both vacancy and interstitial diffusion, with the dynamic annealing rate limited by the migration and interaction of vacancies.

Revealing the Solvation Structure and Dynamics of Carbonate Electrolytes in Lithium-Ion Batteries by Two-Dimensional Infrared Spectrum Modeling.

Science.gov (United States)

Liang, Chungwen; Kwak, Kyungwon; Cho, Minhaeng

2017-12-07

Carbonate electrolytes in lithium-ion batteries play a crucial role in conducting lithium ions between two electrodes. Mixed solvent electrolytes consisting of linear and cyclic carbonates are commonly used in commercial lithium-ion batteries. To understand how the linear and cyclic carbonates introduce different solvation structures and dynamics, we performed molecular dynamics simulations of two representative electrolyte systems containing either linear or cyclic carbonate solvents. We then modeled their two-dimensional infrared (2DIR) spectra of the carbonyl stretching mode of these carbonate molecules. We found that the chemical exchange process involving formation and dissociation of lithium-ion/carbonate complexes is responsible for the growth of 2DIR cross peaks with increasing waiting time. In addition, we also found that cyclic carbonates introduce faster dynamics of dissociation and formation of lithium-ion/carbonate complexes than linear carbonates. These findings provide new insights into understanding the lithium-ion mobility and its interplay with solvation structure and ultrafast dynamics in carbonate electrolytes used in lithium-ion batteries.

Three-stage classical molecular dynamics model for simulation of heavy-ion fusion

Directory of Open Access Journals (Sweden)

Godre Subodh S.

2015-01-01

Full Text Available A three-stage Classical Molecular Dynamics (3S-CMD approach for heavy-ion fusion is developed. In this approach the Classical Rigid-Body Dynamics simulation for heavy-ion collision involving light deformed nucleus is initiated on their Rutherford trajectories at very large initial separation. Collision simulation is then followed by relaxation of the rigid-body constrains for one or both the colliding nuclei at distances close to the barrier when the trajectories of all the nucleons are obtained in a Classical Molecular Dynamics approach. This 3S-CMD approach explicitly takes into account not only the long range Coulomb reorientation of the deformed collision partner but also the internal vibrational excitations of one or both the nuclei at distances close to the barrier. The results of the dynamical simulation for 24Mg+208Pb collision show significant modification of the fusion barrier and calculated fusion cross sections due to internal excitations.

Extraction of highly charged ions from the Berlin Electron Beam Ion Trap for interactions with a gas target

International Nuclear Information System (INIS)

Allen, F.I.; Biedermann, C.; Radtke, R.; Fussmann, G.

2006-01-01

Highly charged ions are extracted from the Berlin Electron Beam Ion Trap for investigations of charge exchange with a gas target. The classical over-the-barrier model for slow highly charged ions describes this process, whereby one or more electrons are captured from the target into Rydberg states of the ion. The excited state relaxes via a radiative cascade of the electron to ground energy. The cascade spectra are characteristic of the capture state. We investigate x-ray photons emitted as a result of interactions between Ar 17+ ions at energies ≤5q keV with Ar atoms. Of particular interest is the velocity dependence of the angular momentum capture state l c

Influence of nonelectrostatic ion-ion interactions on double-layer capacitance

Science.gov (United States)

Zhao, Hui

2012-11-01

Recently a Poisson-Helmholtz-Boltzmann (PHB) model [Bohinc , Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.85.031130 85, 031130 (2012)] was developed by accounting for solvent-mediated nonelectrostatic ion-ion interactions. Nonelectrostatic interactions are described by a Yukawa-like pair potential. In the present work, we modify the PHB model by adding steric effects (finite ion size) into the free energy to derive governing equations. The modified PHB model is capable of capturing both ion specificity and ion crowding. This modified model is then employed to study the capacitance of the double layer. More specifically, we focus on the influence of nonelectrostatic ion-ion interactions on charging a double layer near a flat surface in the presence of steric effects. We numerically compute the differential capacitance as a function of the voltage under various conditions. At small voltages and low salt concentrations (dilute solution), we find out that the predictions from the modified PHB model are the same as those from the classical Poisson-Boltzmann theory, indicating that nonelectrostatic ion-ion interactions and steric effects are negligible. At moderate voltages, nonelectrostatic ion-ion interactions play an important role in determining the differential capacitance. Generally speaking, nonelectrostatic interactions decrease the capacitance because of additional nonelectrostatic repulsion among excess counterions inside the double layer. However, increasing the voltage gradually favors steric effects, which induce a condensed layer with crowding of counterions near the electrode. Accordingly, the predictions from the modified PHB model collapse onto those computed by the modified Poisson-Boltzmann theory considering steric effects alone. Finally, theoretical predictions are compared and favorably agree with experimental data, in particular, in concentrated solutions, leading one to conclude that the modified PHB model adequately predicts the diffuse

Plasma channel and Z-pinch dynamics for heavy ion transport

Energy Technology Data Exchange (ETDEWEB)

Ponce-Marquez, David [Univ. of California, Berkeley, CA (United States)

2002-01-01

A self stabilized, free standing, z-pinch plasma channel has been proposed to deliver the high intensity heavy ion beam from the end of a driver to the fuel target in a heavy ion inertial fusion power plant. The z-pinch relaxes emittance and energy spread requirements requiring a lower cost driver. A z-pinch transport would reduce the number of beam entry port holes to the target chamber from over a hundred to four as compared to neutralized ballistic focusing thus reducing the driver hardware exposure to neutron flux. Experiments where a double pulse discharge technique is used, z-pinch plasma channels with enhanced stability are achieved. Typical parameters are 7 kV pre-pulse discharge and 30 kV main bank discharge with 50 kA of channel current in a 7 torr background gas atmosphere. This work is an experimental study of these plasma channels examining the relevant physics necessary to understand and model such plasmas. Laser diagnostics measured the dynamical properties of neutrals and plasma. Schlieren and phase contrast techniques probe the pre-pulse gas dynamics and infrared interferometry and faraday effect polarimetry are used on the z-pinch to study its electron density and current distribution. Stability and repeatability of the z-pinch depend on the initial conditions set by the pre-pulse. Results show that the z-pinch channel is wall stabilized by an on-axis gas density depression created by the pre-pulse through hydrodynamic expansion where the ratio of the initial gas density to the final gas density is > 10/1. The low on-axis density favors avalanching along the desired path for the main bank discharge. Pinch time is around 2 s from the main bank discharge initiation with a FWHM of ~ 2 cm. Results also show that typical main bank discharge plasma densities reach 10¹⁷ cm^-3 peak on axis for a 30 kV, 7 torr gas nitrogen discharge. Current rise time is limited by the circuit-channel inductance with the highest contribution to the

Coupled acoustic-gravity field for dynamic evaluation of ion exchange with a single resin bead.

Science.gov (United States)

Kanazaki, Takahiro; Hirawa, Shungo; Harada, Makoto; Okada, Tetsuo

2010-06-01

A coupled acoustic-gravity field is efficient for entrapping a particle at the position determined by its acoustic properties rather than its size. This field has been applied to the dynamic observation of ion-exchange reactions occurring in a single resin bead. The replacement of counterions in an ion-exchange resin induces changes in its acoustic properties, such as density and compressibility. Therefore, we can visually trace the advancement of an ion-exchange reaction as a time change in the levitation position of a resin bead entrapped in the field. Cation-exchange reactions occurring in resin beads with diameters of 40-120 microm are typically completed within 100-200 s. Ion-exchange equilibrium or kinetics is often evaluated with off-line chemical analyses, which require a batch amount of ion exchangers. Measurements with a single resin particle allow us to evaluate ion-exchange dynamics and kinetics of ions including those that are difficult to measure by usual off-line analyses. The diffusion properties of ions in resins have been successfully evaluated from the time change in the levitation positions of resin beads.

From Brownian Dynamics to Markov Chain: An Ion Channel Example

KAUST Repository

Chen, Wan; Erban, Radek; Chapman, S. Jonathan

2014-01-01

is illustrated with a two-ion one-well channel. The stationary probability of states is compared with that from both Brownian dynamics simulation and the hierarchical Fokker-Planck equations. The conductivity of the channel is also studied, and the optimal

Capturing Dynamics of Biased Attention: Are New Attention Variability Measures the Way Forward?

Directory of Open Access Journals (Sweden)

Anne-Wil Kruijt

Full Text Available New indices, calculated on data from the widely used Dot Probe Task, were recently proposed to capture variability in biased attention allocation. We observed that it remains unclear which data pattern is meant to be indicative of dynamic bias and thus to be captured by these indices. Moreover, we hypothesized that the new indices are sensitive to SD differences at the response time (RT level in the absence of bias.Randomly generated datasets were analyzed to assess properties of the Attention Bias Variability (ABV and Trial Level Bias Score (TL-BS indices. Sensitivity to creating differences in 1 RT standard deviation, 2 mean RT, and 3 bias magnitude were assessed. In addition, two possible definitions of dynamic attention bias were explored by creating differences in 4 frequency of bias switching, and 5 bias magnitude in the presence of constant switching.ABV and TL-BS indices were found highly sensitive to increasing SD at the response time level, insensitive to increasing bias, linearly sensitive to increasing bias magnitude in the presence of bias switches, and non-linearly sensitive to increasing the frequency of bias switches. The ABV index was also found responsive to increasing mean response times in the absence of bias.Recently proposed DPT derived variability indices cannot uncouple measurement error from bias variability. Significant group differences may be observed even if there is no bias present in any individual dataset. This renders the new indices in their current form unfit for empirical purposes. Our discussion focuses on fostering debate and ideas for new research to validate the potentially very important notion of biased attention being dynamic.

Doppler coherence imaging of ion dynamics in VINETA.II and ASDEX-upgrade

Energy Technology Data Exchange (ETDEWEB)

Gradic, Dorothea; Ford, Oliver; Wolf, Robert [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); Lunt, Tilmann [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

2016-07-01

In magnetically confining plasma experiments, diagnosis of ion flows is of great importance to measure the plasma response to the magnetic field or the exhaust particle flows in the divertor areas. Doppler coherence imaging spectroscopy (CIS) is a relatively new technique for the observation of plasma bulk ion dynamics. It is a passive optical diagnostic enabling line-integrated measurements to obtain 2D images of the ion flow and ion temperature. The general principle is similar to traditional Doppler spectroscopy, however CIS uses an imaging interferometer to perform narrow-bandwidth Fourier spectroscopy. A major advantage of the coherence imaging technique is the large amount of spatial information recovered. This allows tomographic inversion of the line-integrated measurements. With existing CIS setups, scrape-off-layer and high field side edge impurity flows could be observed in the MAST, core and edge poloidal He II flows in the WEGA stellarator and divertor impurity flows in DIII-D. The main objective of this study is the research of ion dynamics in the small linear plasma experiment VINETA.II and ASDEX-Upgrade. First Doppler CIS measurements from Ar-II plasma discharges in VINETA.II and He-II, C-III divertor flows in ASDEX-Upgrade and their preliminary interpretation will be presented.

Capturing dynamic processes of change in GROW mutual help groups for mental health.

Science.gov (United States)

Finn, Lizzie D; Bishop, Brian J; Sparrow, Neville

2009-12-01

The need for a model that can portray dynamic processes of change in mutual help groups for mental health (MHGMHs) is emphasized. A dynamic process model has the potential to capture a more comprehensive understanding of how MHGMHs may assist their members. An investigation into GROW, a mutual help organization for mental health, employed ethnographic, phenomenological and collaborative research methods. The study examined how GROW impacts on psychological well being. Study outcomes aligned with the social ecological paradigm (Maton in Understanding the self-help organization: frameworks and findings. Sage, Thousand Oaks 1994) indicating multifactorial processes of change at and across three levels of analysis: group level, GROW program/community level and individual level. Outcome themes related to life skills acquisition and a change in self-perception in terms of belonging within community and an increased sense of personal value. The GROW findings are used to assist development of a dynamic multi-dimensional process model to explain how MHGMHs may promote positive change.

DYNAMICS OF HIGH ENERGY IONS AT A STRUCTURED COLLISIONLESS SHOCK FRONT

Energy Technology Data Exchange (ETDEWEB)

Gedalin, M. [Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva (Israel); Dröge, W.; Kartavykh, Y. Y., E-mail: gedalin@bgu.ac.il [Institute for Theoretical Physics and Astrophysics, University of Würzburg, Würzburg (Germany)

2016-07-10

Ions undergoing first-order Fermi acceleration at a shock are scattered in the upstream and downstream regions by magnetic inhomogeneities. For high energy ions this scattering is efficient at spatial scales substantially larger than the gyroradius of the ions. The transition from one diffusive region to the other occurs via crossing the shock, and the ion dynamics during this crossing is mainly affected by the global magnetic field change between the upstream and downstream region. We study the effects of the fine structure of the shock front, such as the foot-ramp-overshoot profile and the phase-standing upstream and downstream magnetic oscillations. We also consider time dependent features, including reformation and large amplitude coherent waves. We show that the influence of the spatial and temporal structure of the shock front on the dependence of the transition and reflection on the pitch angle of the ions is already weak at ion speeds five times the speed of the upstream flow.

Technique for increasing dynamic range of space-borne ion composition instruments

International Nuclear Information System (INIS)

Burch, J.L.; Miller, G.P.; Santos, A. de los; Pollock, C.J.; Pope, S.E.; Valek, P. W.; Young, D.T.

2005-01-01

The dynamic range of ion composition spectrometers is limited by several factors, including saturation of particle counters and spillover of signals from highly dominant species into channels tuned to minor species. Instruments designed for composition measurements of hot plasmas in space can suffer greatly from both of these problems because of the wide energy range required and the wide disparity in fluxes encountered in various regions of interest. In order to detect minor ions in regions of very weak fluxes, geometry factors need to be as large as possible within the mass and volume resources available. As a result, problems with saturation by the dominant fluxes and spillover to minor-ion channels in plasma regions with intense fluxes become especially acute. This article reports on a technique for solving the dynamic-range problem in the few eV to several keV energy/charge range that is of central importance for space physics research where the dominant ion is of low mass/charge (typically H + ), and the minor ions are of higher mass/charge (typically O + ). The technique involves employing a radio-frequency modulation of the deflection electric field in the back section of an electrostatic analyzer in a time-of-flight instrument. This technique is shown to reduce H + counts by a controllable amount of up to factors of 1000 while reducing O + counts by only a few percent that can be calibrated

Dynamics of beam-driven Langmuir and ion-acoustic waves including electrostatic decay

International Nuclear Information System (INIS)

Li, B.; Willes, A.J.; Robinson, P.A.; Cairns, I.H.

2003-01-01

The evolution of Langmuir waves and ion-acoustic waves stimulated by a hot electron beam in an initially homogeneous plasma is investigated numerically in time, position, and wave number space. Quasilinear interactions between the beam particles and Langmuir waves, nonlinear interactions between the Langmuir and ion-acoustic waves through Langmuir decay processes, and spontaneous emission are taken into account in the kinetic theory employed. For illustrative parameters of those in the solar wind near 1 a.u., nonlinear Langmuir decays are observed to transfer the beam-driven Langmuir waves rapidly out of resonance. The scattered Langmuir waves then undergo further decays, moving sequentially toward small wave numbers, until decay is kinematically prohibited. The main features of the evolution of Langmuir and ion-acoustic waves are spatially inhomogeneous. The scattered Langmuir spectra increase and eventually reach or exceed the beam-driven Langmuir spectra at a given spatial location (except in regions where further decays proceed). The ion-acoustic waves are relatively weak and subject to damping at the later stages of their evolution. The development of fine structures in the product Langmuir and ion-acoustic waves are observed, due to depletion of their energy by decay and dominant damping effects, respectively. The propagation of the beam is essentially unaffected by the operation of the decay process. The decay process is thus slaved to the primary beam-plasma evolution, as assumed in previous studies. A variation of the ratio of electron temperature to ion temperature is found to affect not only the ion-acoustic wave levels through effects on the damping rate, but also the dynamics of decay via effects on the decay rate. The latter was not addressed in previous studies. Furthermore, spontaneous emission of ion-acoustic waves is found to affect the dynamics of decay, thus its inclusion is necessary to correctly model the Langmuir and ion-acoustic spectra

Getting the ion-protein interactions right in molecular dynamics simulations

Czech Academy of Sciences Publication Activity Database

Duboué-Dijon, Elise; Mason, Philip E.; Jungwirth, Pavel

2017-01-01

Roč. 46, Suppl 1 (2017), S66 ISSN 0175-7571. [IUPAB congress /19./ and EBSA congress /11./. 16.07.2017-20.07.2017, Edinburgh] Institutional support: RVO:61388963 Keywords : ion-protein interaction * molecular dynamics simulations * neutron scattering * insulin Subject RIV: BO - Biophysics

POTENTIALS OF IMAGE BASED ACTIVE RANGING TO CAPTURE DYNAMIC SCENES

Directory of Open Access Journals (Sweden)

B. Jutzi

2012-09-01

Full Text Available Obtaining a 3D description of man-made and natural environments is a basic task in Computer Vision and Remote Sensing. To this end, laser scanning is currently one of the dominating techniques to gather reliable 3D information. The scanning principle inherently needs a certain time interval to acquire the 3D point cloud. On the other hand, new active sensors provide the possibility of capturing range information by images with a single measurement. With this new technique image-based active ranging is possible which allows capturing dynamic scenes, e.g. like walking pedestrians in a yard or moving vehicles. Unfortunately most of these range imaging sensors have strong technical limitations and are not yet sufficient for airborne data acquisition. It can be seen from the recent development of highly specialized (far-range imaging sensors – so called flash-light lasers – that most of the limitations could be alleviated soon, so that future systems will be equipped with improved image size and potentially expanded operating range. The presented work is a first step towards the development of methods capable for application of range images in outdoor environments. To this end, an experimental setup was set up for investigating these proposed possibilities. With the experimental setup a measurement campaign was carried out and first results will be presented within this paper.

Modelling of caesium dynamics in the negative ion sources at BATMAN and ELISE

Science.gov (United States)

Mimo, A.; Wimmer, C.; Wünderlich, D.; Fantz, U.

2017-08-01

The knowledge of Cs dynamics in negative hydrogen ion sources is a primary issue to achieve the ITER requirements for the Neutral Beam Injection (NBI) systems, i.e. one hour operation with an accelerated ion current of 40 A of D- and a ratio between negative ions and co-extracted electrons below one. Production of negative ions is mostly achieved by conversion of hydrogen/deuterium atoms on a converter surface, which is caesiated in order to reduce the work function and increase the conversion efficiency. The understanding of the Cs transport and redistribution mechanism inside the source is necessary for the achievement of high performances. Cs dynamics was therefore investigated by means of numerical simulations performed with the Monte Carlo transport code CsFlow3D. Simulations of the prototype source (1/8 of the ITER NBI source size) have shown that the plasma distribution inside the source has the major effect on Cs dynamics during the pulse: asymmetry of the plasma parameters leads to asymmetry in Cs distribution in front of the plasma grid. The simulated time traces and the general simulation results are in agreement with the experimental measurements. Simulations performed for the ELISE testbed (half of the ITER NBI source size) have shown an effect of the vacuum phase time on the amount and stability of Cs during the pulse. The sputtering of Cs due to back-streaming ions was reproduced by the simulations and it is in agreement with the experimental observation: this can become a critical issue during long pulses, especially in case of continuous extraction as foreseen for ITER. These results and the acquired knowledge of Cs dynamics will be useful to have a better management of Cs and thus to reduce its consumption, in the direction of the demonstration fusion power plant DEMO.

Photodissociation spectroscopy and dynamics of free radicals, clusters, and ions

Energy Technology Data Exchange (ETDEWEB)

Choi, Hyeon [Univ. of California, Berkeley, CA (United States)

1999-12-01

The photodissociation spectroscopy and dynamics of free radicals and ions is studied to characterize the dissociative electronic states in these species. To accomplish this, a special method of radical production, based on the photodetachment of the corresponding negative ion, has been combined with the technique of fast beam photofragment translational spectroscopy. The photofragment yield as a function of photon energy is obtained, mapping out the dissociative and predissociative electronic states. Branching ratios to various product channels, the translational energy distributions of the fragments, and bond dissociation energies are then determined at selected photon energies. The detailed picture of photodissociation dynamics is provided with the aid of ab initio calculations and a statistical model to interpret the observed data. Important reaction intermediates in combustion reactions have been studied: CCO, C₂H₅O, and linear C_n (n = 4--6).

Ion optics and beam dynamics optimization at the HESR storage ring for the SPARC experiments with highly charged heavy ions

International Nuclear Information System (INIS)

Kovalenko, Oleksandr

2015-01-01

The High-Energy Storage Ring (HESR) is a part of an upcoming International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt. A key part of a scientific program, along with antiproton physics, will be physics with highly-charged heavy ions. Phase-space cooled beams together with fixed internal target will provide an excellent environment for storage ring experiments at the HESR for the SPARC collaboration. Until recently, however, the existing ion optical lattice for the HESR was designed only for the experiments with antiproton beams. The thesis presents a new ion optical mode developed specifically for the operation of the HESR with highly charged heavy ions. The presence of the errors, such as beam momentum spread, magnetic field impurities or magnets misalignments, leads to disruption of beam dynamics: exciting of resonant motion and loss of beam stability. Within the paper, these effects are investigated with the help of numerical codes for particle accelerator design and simulation MAD-X and MIRKO. A number of correction techniques are applied to minimize the nonlinear impact on the beam dynamics and improve the experimental conditions. The application of the analytical and numerical tools is demonstrated in the experiment with uranium U 90+ beam at the existing storage ring ESR, GSI.

Ion optics and beam dynamics optimization at the HESR storage ring for the SPARC experiments with highly charged heavy ions

Energy Technology Data Exchange (ETDEWEB)

Kovalenko, Oleksandr

2015-06-24

The High-Energy Storage Ring (HESR) is a part of an upcoming International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt. A key part of a scientific program, along with antiproton physics, will be physics with highly-charged heavy ions. Phase-space cooled beams together with fixed internal target will provide an excellent environment for storage ring experiments at the HESR for the SPARC collaboration. Until recently, however, the existing ion optical lattice for the HESR was designed only for the experiments with antiproton beams. The thesis presents a new ion optical mode developed specifically for the operation of the HESR with highly charged heavy ions. The presence of the errors, such as beam momentum spread, magnetic field impurities or magnets misalignments, leads to disruption of beam dynamics: exciting of resonant motion and loss of beam stability. Within the paper, these effects are investigated with the help of numerical codes for particle accelerator design and simulation MAD-X and MIRKO. A number of correction techniques are applied to minimize the nonlinear impact on the beam dynamics and improve the experimental conditions. The application of the analytical and numerical tools is demonstrated in the experiment with uranium U{sup 90+} beam at the existing storage ring ESR, GSI.

Kinetic modeling of particle dynamics in H{sup −} negative ion sources (invited)

Energy Technology Data Exchange (ETDEWEB)

Hatayama, A., E-mail: akh@ppl.appi.keio.ac.jp; Shibata, T.; Nishioka, S.; Ohta, M.; Yasumoto, M.; Nishida, K.; Yamamoto, T. [Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522 (Japan); Miyamoto, K. [Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima 772-8502 (Japan); Fukano, A. [Monozukuri Department, Tokyo Metropolitan College of Industrial Technology, Shinagawa, Tokyo 140-0011 (Japan); Mizuno, T. [Department of Management Science, College of Engineering, Tamagawa University, Machida, Tokyo 194-8610 (Japan)

2014-02-15

Progress in the kinetic modeling of particle dynamics in H{sup −} negative ion source plasmas and their comparisons with experiments are reviewed, and discussed with some new results. Main focus is placed on the following two topics, which are important for the research and development of large negative ion sources and high power H{sup −} ion beams: (i) Effects of non-equilibrium features of EEDF (electron energy distribution function) on H{sup −} production, and (ii) extraction physics of H{sup −} ions and beam optics.

Ion sources for medical accelerators

Science.gov (United States)

Barletta, W. A.; Chu, W. T.; Leung, K. N.

1998-02-01

Advanced injector systems for proton synchrotrons and accelerator-based boron neutron capture therapy systems are being developed at the Lawrence Berkeley National Laboratory. Multicusp ion sources, particularly those driven by radio frequency, have been tested for these applications. The use of a radio frequency induction discharge provides clean, reliable, and long-life source operation. It has been demonstrated that the multicusp ion source can provide good-quality positive hydrogen ion beams with a monatomic ion fraction higher than 90%. The extractable ion current densities from this type of source can meet the injector requirements for both proton synchrotron and accelerator-based boron neutron capture therapy projects.

Capturing Context-Related Change in Emotional Dynamics via Fixed Moderated Time Series Analysis.

Science.gov (United States)

Adolf, Janne K; Voelkle, Manuel C; Brose, Annette; Schmiedek, Florian

2017-01-01

Much of recent affect research relies on intensive longitudinal studies to assess daily emotional experiences. The resulting data are analyzed with dynamic models to capture regulatory processes involved in emotional functioning. Daily contexts, however, are commonly ignored. This may not only result in biased parameter estimates and wrong conclusions, but also ignores the opportunity to investigate contextual effects on emotional dynamics. With fixed moderated time series analysis, we present an approach that resolves this problem by estimating context-dependent change in dynamic parameters in single-subject time series models. The approach examines parameter changes of known shape and thus addresses the problem of observed intra-individual heterogeneity (e.g., changes in emotional dynamics due to observed changes in daily stress). In comparison to existing approaches to unobserved heterogeneity, model estimation is facilitated and different forms of change can readily be accommodated. We demonstrate the approach's viability given relatively short time series by means of a simulation study. In addition, we present an empirical application, targeting the joint dynamics of affect and stress and how these co-vary with daily events. We discuss potentials and limitations of the approach and close with an outlook on the broader implications for understanding emotional adaption and development.

Characteristics and dynamics of the boundary layer in RF-driven sources for negative hydrogen ions

International Nuclear Information System (INIS)

Wimmer, Christian

2014-01-01

The design of the neutral beam injection system of the upcoming ITER fusion device is based on the IPP (Max-Planck-Institut fuer Plasmaphysik, Garching) prototype source for negative hydrogen ions. The latter consists of a driver, in which hydrogen (or deuterium) molecules are dissociated in a large degree in a hydrogen plasma; the plasma expands then towards the plasma grid, on which negative hydrogen ions are formed by conversion of atoms or positive ions by the surface process and are extracted in the following accompanied by the co-extraction of electrons via a three grid system. Electrons are removed out of the extracted beam prior full acceleration using deflection magnets, bending them onto the second grid. The thermal load limits the tolerable amount of co-extracted electrons. A magnetic filter field in the expansion chamber reduces the electron temperature and density, on the one hand in order to minimize the destruction process of negative hydrogen ions by electron collisions and on the other hand in order to reduce the co-extracted electron current density. Caesium is evaporated into the source for an effective production of negative hydrogen ions, lowering the work function of the plasma grid. Due to the high chemical reactivity of caesium, the high vacuum condition in the source and the plasma-wall interaction, complex redistribution processes of Cs take place in the ion source. The boundary layer is the plasma volume between the magnetic filter field and the plasma grid, in which the most important physics of the negative ion source takes place: the production of negative hydrogen ions at the plasma grid, their transport through the plasma and the following extraction. A deeper understanding of the plasma and Cs dynamics in the boundary layer is desirable in order to achieve a stable long-pulse operation as well as to identify possible future improvements. For this reason, the boundary layer of the prototype source has been characterized in this work

Coupled-channel calculations of partial capture cross sections in multiply charged ion collisions with hydrogen

International Nuclear Information System (INIS)

Hansen, J.P.; Taulbjerg, K.; University of Tennessee, Knoxville, Tennessee 37996)

1989-01-01

Partial cross sections for electron capture in 1--50-keV collisions of Ar 6+ and Ar 8+ with atomic hydrogen have been calculated using an atomic expansion including two complete principal shells of final states (n=4,5 for Ar 6+ and n=5,6 for Ar 8+ ). The qualitative structure of the results is in good accord with a reaction window picture. The results for Ar 6+ ions are in agreement with published experimental data when precaution is taken with respect to uncertainties in absolute normalization of the data and with respect to a proper analysis of translation energy spectra at lower impact energies. The limited experimental data for Ar 8+ do not agree with the present results

Capturing complexity in work disability research: application of system dynamics modeling methodology.

Science.gov (United States)

Jetha, Arif; Pransky, Glenn; Hettinger, Lawrence J

2016-01-01

Work disability (WD) is characterized by variable and occasionally undesirable outcomes. The underlying determinants of WD outcomes include patterns of dynamic relationships among health, personal, organizational and regulatory factors that have been challenging to characterize, and inadequately represented by contemporary WD models. System dynamics modeling (SDM) methodology applies a sociotechnical systems thinking lens to view WD systems as comprising a range of influential factors linked by feedback relationships. SDM can potentially overcome limitations in contemporary WD models by uncovering causal feedback relationships, and conceptualizing dynamic system behaviors. It employs a collaborative and stakeholder-based model building methodology to create a visual depiction of the system as a whole. SDM can also enable researchers to run dynamic simulations to provide evidence of anticipated or unanticipated outcomes that could result from policy and programmatic intervention. SDM may advance rehabilitation research by providing greater insights into the structure and dynamics of WD systems while helping to understand inherent complexity. Challenges related to data availability, determining validity, and the extensive time and technical skill requirements for model building may limit SDM's use in the field and should be considered. Contemporary work disability (WD) models provide limited insight into complexity associated with WD processes. System dynamics modeling (SDM) has the potential to capture complexity through a stakeholder-based approach that generates a simulation model consisting of multiple feedback loops. SDM may enable WD researchers and practitioners to understand the structure and behavior of the WD system as a whole, and inform development of improved strategies to manage straightforward and complex WD cases.

Dynamic simulation and optimization of an industrial-scale absorption tower for CO2 capturing from ethane gas

Directory of Open Access Journals (Sweden)

Babak Pouladi

2016-11-01

Full Text Available This article considers a process technology based on absorption for CO2 capturing of ethane gas in phase 9 and 10 of south pars in Iran using diethanolamine (DEA as absorbent solvent. This CO2 capture plant was designed to achieve 85% CO2 recovery and obtain 19 ppm the CO2 concentration in the outlet of absorber. ASPEN–HYSYS software was used for the dynamic simulation of a commercial-scale CO2 capture plant and amine Pkg equation was chosen from the fluid property package for calculating the thermodynamic properties of the process. A static approach for optimization was used to evaluate the optimum conditions. This research revealed that pressure variation does not have any considerable changes in the absorption process, while both amine inlet temperature and volumetric flow rate increment enhance the absorption tower efficiency. The effect of temperature was very significant as shown in the dynamic study plots. The optimum condition for CO2 absorption from a stream of ethane gas with molar flow rate of 2118 kg mol h−1 was obtained 75 m3  h−1 of amine at 53 °C and 24 bar. This optimized condition is acceptable from economical, safe as well as feasible point of view.

Experimental investigation of the formation of negative hydrogen ions in collisions between positive ions and atomic or molecular targets

International Nuclear Information System (INIS)

Lattouf, Elie

2013-01-01

The formation of the negative hydrogen ion (H - ) in collisions between a positive ion and a neutral atomic or molecular target is studied experimentally at impact energies of a few keV. The doubly-differential cross sections for H - formation are measured as a function of the kinetic energy and emission angle for the collision systems OH + + Ar and O + + H 2 O at 412 eV/a.m.u. These H - ions can be emitted at high energies (keV) in hard quasi-elastic two-body collisions involving a large momentum transfer to the H center. However, H - anions are preferentially emitted at low energy (eV) due to soft many-body (≥ 2) collisions resulting in a low momentum transfer. The formation of H - ions by electron capture follows excitation or ionization of the molecule. The molecular fragmentation dynamics is modeled to simulate the emission of H - ions. The overall good agreement between the simulation and the experiment leads to the understanding of most of the experimental observations. (author) [fr

Dynamics of fast ions during sawtooth oscillations in the TEXTOR tokamak measured by collective Thomson scattering

DEFF Research Database (Denmark)

Nielsen, Stefan Kragh; Salewski, Mirko; Bindslev, Henrik

2011-01-01

Experimental investigations of sawteeth interaction with fast ions measured by collective Thomson scattering on TEXTOR are presented. Time-resolved measurements of localized 1D fast-ion distribution functions allow us to study fast-ion dynamics during several sawtooth cycles. Sawtooth oscillation...

Electrodiffusive model for astrocytic and neuronal ion concentration dynamics.

Directory of Open Access Journals (Sweden)

Geir Halnes

Full Text Available The cable equation is a proper framework for modeling electrical neural signalling that takes place at a timescale at which the ionic concentrations vary little. However, in neural tissue there are also key dynamic processes that occur at longer timescales. For example, endured periods of intense neural signaling may cause the local extracellular K(+-concentration to increase by several millimolars. The clearance of this excess K(+ depends partly on diffusion in the extracellular space, partly on local uptake by astrocytes, and partly on intracellular transport (spatial buffering within astrocytes. These processes, that take place at the time scale of seconds, demand a mathematical description able to account for the spatiotemporal variations in ion concentrations as well as the subsequent effects of these variations on the membrane potential. Here, we present a general electrodiffusive formalism for modeling of ion concentration dynamics in a one-dimensional geometry, including both the intra- and extracellular domains. Based on the Nernst-Planck equations, this formalism ensures that the membrane potential and ion concentrations are in consistency, it ensures global particle/charge conservation and it accounts for diffusion and concentration dependent variations in resistivity. We apply the formalism to a model of astrocytes exchanging ions with the extracellular space. The simulations show that K(+-removal from high-concentration regions is driven by a local depolarization of the astrocyte membrane, which concertedly (i increases the local astrocytic uptake of K(+, (ii suppresses extracellular transport of K(+, (iii increases axial transport of K(+ within astrocytes, and (iv facilitates astrocytic relase of K(+ in regions where the extracellular concentration is low. Together, these mechanisms seem to provide a robust regulatory scheme for shielding the extracellular space from excess K(+.

Photodissociation and charge transfer dynamics of negative ions studied with femtosecond photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Zanni, Martin Thomas [Univ. of California, Berkeley, CA (United States)

1999-12-01

This dissertation presents studies aimed at understanding the potential energy surfaces and dynamics of isolated negative ions, and the effects of solvent on each. Although negative ions play important roles in atmospheric and solution phase chemistry, to a large extent the ground and excited state potential energy surfaces of gas phase negative ions are poorly characterized, and solvent effects even less well understood. In an effort to fill this gap, the author's coworkers and the author have developed a new technique, anion femtosecond photoelectron spectroscopy, and applied it to gas phase photodissociation and charge transfer processes. Studies are presented that (1) characterize the ground and excited states of isolated and clustered anions, (2) monitor the photodissociation dynamics of isolated and clustered anions, and (3) explore the charge-transfer-to-solvent states of atomic iodide clustered with polar and non-polar solvents.

Photodissociation and charge transfer dynamics of negative ions studied with femtosecond photoelectron spectroscopy

International Nuclear Information System (INIS)

Zanni, Martin T.

1999-01-01

This dissertation presents studies aimed at understanding the potential energy surfaces and dynamics of isolated negative ions, and the effects of solvent on each. Although negative ions play important roles in atmospheric and solution phase chemistry, to a large extent the ground and excited state potential energy surfaces of gas phase negative ions are poorly characterized, and solvent effects even less well understood. In an effort to fill this gap, the author's coworkers and the author have developed a new technique, anion femtosecond photoelectron spectroscopy, and applied it to gas phase photodissociation and charge transfer processes. Studies are presented that (1) characterize the ground and excited states of isolated and clustered anions, (2) monitor the photodissociation dynamics of isolated and clustered anions, and (3) explore the charge-transfer-to-solvent states of atomic iodide clustered with polar and non-polar solvents

Comparison of linear intrascan and interscan dynamic ranges of Orbitrap and ion-mobility time-of-flight mass spectrometers.

Science.gov (United States)

Kaufmann, Anton; Walker, Stephan

2017-11-30

The linear intrascan and interscan dynamic ranges of mass spectrometers are important in metabolome and residue analysis. A large linear dynamic range is mandatory if both low- and high-abundance ions have to be detected and quantitated in heavy matrix samples. These performance criteria, as provided by modern high-resolution mass spectrometry (HRMS), were systematically investigated. The comparison included two generations of Orbitraps, and an ion mobility quadrupole time-of-flight (QTOF) system In addition, different scan modes, as provided by the utilized instruments, were investigated. Calibration curves of different compounds covering a concentration range of five orders of magnitude were measured to evaluate the linear interscan dynamic range. The linear intrascan dynamic range and the resulting mass accuracy were evaluated by repeating these measurements in the presence of a very intense background. Modern HRMS instruments can show linear dynamic ranges of five orders of magnitude. Often, however, the linear dynamic range is limited by the detection capability (sensitivity and selectivity) and by the electrospray ionization. Orbitraps, as opposed to TOF instruments, show a reduced intrascan dynamic range. This is due to the limited C-trap and Orbitrap capacity. The tested TOF instrument shows poorer mass accuracies than the Orbitraps. In contrast, hyphenation with an ion-mobility device seems not to affect the linear dynamic range. The linear dynamic range of modern HRMS instrumentation has been significantly improved. This also refers to the virtual absence of systematic mass shifts at high ion abundances. The intrascan dynamic range of the current Orbitrap technology may still be a limitation when analyzing complex matrix extracts. On the other hand, the linear dynamic range is not only limited by the detector technology, but can also be shortened by peripheral devices, where the ionization and transfer of ions take place. Copyright © 2017 John Wiley

Basic atomic interactions of accelerated heavy ions in matter atomic interactions of heavy ions

CERN Document Server

Tolstikhina, Inga; Winckler, Nicolas; Shevelko, Viacheslav

2018-01-01

This book provides an overview of the recent experimental and theoretical results on interactions of heavy ions with gaseous, solid and plasma targets from the perspective of atomic physics. The topics discussed comprise stopping power, multiple-electron loss and capture processes, equilibrium and non-equilibrium charge-state fractions in penetration of fast ion beams through matter including relativistic domain. It also addresses mean charge-states and equilibrium target thickness in ion-beam penetrations, isotope effects in low-energy electron capture, lifetimes of heavy ion beams, semi-empirical formulae for effective cross sections. The book is intended for researchers and graduate students working in atomic, plasma and accelerator physics.

Structure and Dynamics of Water on Aqueous Barium Ion and the {001} Barite Surface

International Nuclear Information System (INIS)

Stack, Andrew G.; Rustad, James R.

2007-01-01

The structure of water and its dynamics affect a number of fundamental properties of an interface. Yet, these properties are often inaccessible experimentally and computational studies including solvent are comparatively few. Here, we estimate the structure and kinetics of water exchange of aqueous barium ions and barium ions within the {001} barite surface using molecular dynamics and the reactive flux method. For the aqueous ion, the Ba-O distance to water in the first hydration shell was found to be 280 pm with a coordination number of 8.3, and the best estimate of the exchange rate constant is 4.8 x 10 9 s -1 , closely matching experimental estimates. For the barite surface, the first shell water distance was 282 pm, with a coordination number of 0.9 and the best estimate of the rate constant for exchange is 1.7 x 10 10 s -1 , 3.5 times faster than that of the aqueous ion.

Fast-ion dynamics in the TEXTOR tokamak measured by collective Thomson scattering

International Nuclear Information System (INIS)

Bindslev, H; Nielsen, S K; Porte, L; Hoekzema, J A; Korsholm, S B; Meo, F; Michelsen, P K; Michelsen, S; Oosterbeek, J W; Tsakadze, E L; Westerhof, E; Woskov, P

2007-01-01

The dynamics of fast ion populations in the TEXTOR tokamak are measured by collective Thomson scattering of millimetre wave radiation generated by a gyrotron operated at 110 GHz and 100-150 kW. Temporal evolution of the energetic ion velocity distribution at switch on of neutral beam injection (NBI) and the slowdown after switch off of NBI are measured. The turn on phase of the NBI has, furthermore, been measured in plasmas with a range of electron densities and temperatures. All of these measurements are shown to be in good agreement with simple Fokker-Planck modelling. Bulk ion rotation velocity is also measured

Recent recoil ion momentum spectroscopy experiments at KSU

International Nuclear Information System (INIS)

Abdallah, M.; Cocke, C.L.; Kravis, S.; Montenegro, E.C.; Moshammer, R.; Saleh, L.; Ullrich, J.; Varghese, S.L.; Wolff, W.; Wolf, H.

1997-01-01

Recoil momentum spectroscopy is used to study collisions involving both fast and slow projectiles on He targets. Experiments have been performed on electron capture and loss from fast ions from the KSU LINAC and slow ions from the KSU CRYEBIS using a supersonic jets with a momentum resolution below 0.5 au. Using fast ions, the final states populated in electron capture from He by 10 MeV F 8+ have been resolved with a Q-value resolution of 18 eV, sufficient to separate final channels in which the He + ion is left excited from those in which He + is left in its ground state. With slow ions, electron capture from He by slow bare Ne ions has been studied. A few recent results are discussed. copyright 1997 American Institute of Physics

Calcium ions in aqueous solutions: Accurate force field description aided by ab initio molecular dynamics and neutron scattering

Science.gov (United States)

Martinek, Tomas; Duboué-Dijon, Elise; Timr, Štěpán; Mason, Philip E.; Baxová, Katarina; Fischer, Henry E.; Schmidt, Burkhard; Pluhařová, Eva; Jungwirth, Pavel

2018-06-01

We present a combination of force field and ab initio molecular dynamics simulations together with neutron scattering experiments with isotopic substitution that aim at characterizing ion hydration and pairing in aqueous calcium chloride and formate/acetate solutions. Benchmarking against neutron scattering data on concentrated solutions together with ion pairing free energy profiles from ab initio molecular dynamics allows us to develop an accurate calcium force field which accounts in a mean-field way for electronic polarization effects via charge rescaling. This refined calcium parameterization is directly usable for standard molecular dynamics simulations of processes involving this key biological signaling ion.

Dynamical simulation of heavy ion collisions; VUU and QMD method

International Nuclear Information System (INIS)

Niita, Koji

1992-01-01

We review two simulation methods based on the Vlasov-Uehling-Uhlenbeck (VUU) equation and Quantum Molecular Dynamics (QMD), which are the most widely accepted theoretical framework for the description of intermediate-energy heavy-ion reactions. We show some results of the calculations and compare them with the experimental data. (author)

Molecular Dynamics Simulation of the Antiamoebin Ion Channel: Linking Structure and Conductance

Science.gov (United States)

Wilson, Michael A.; Wei, Chenyu; Bjelkmar, Paer; Wallace, B. A.; Pohorille, Andrew

2011-01-01

Molecular dynamics simulations were carried out in order to ascertain which of the potential multimeric forms of the transmembrane peptaibol channel, antiamoebin, is consistant with its measured conductance. Estimates of the conductance obtained through counting ions that cross the channel and by solving the Nernst-Planck equation yield consistent results, indicating that the motion of ions inside the channel can be satisfactorily described as diffusive.The calculated conductance of octameric channels is markedly higher than the conductance measured in single channel recordings, whereas the tetramer appears to be non-conducting. The conductance of the hexamer was estimated to be 115+/-34 pS and 74+/-20 pS, at 150 mV and 75 mV, respectively, in satisfactory agreement with the value of 90 pS measured at 75 mV. On this basis we propose that the antiamoebin channel consists of six monomers. Its pore is large enough to accommodate K(+) and Cl(-) with their first solvation shells intact. The free energy barrier encountered by K(+) is only 2.2 kcal/mol whereas Cl(-) encounters a substantially higher barrier of nearly 5 kcal/mol. This difference makes the channel selective for cations. Ion crossing events are shown to be uncorrelated and follow Poisson statistics. keywords: ion channels, peptaibols, channel conductance, molecular dynamics

Exploring Ion-Ion Interactions in Aqueous Solutions by a Combination of Molecular Dynamics and Neutron Scattering

Czech Academy of Sciences Publication Activity Database

Kohagen, Miriam; Pluhařová, E.; Mason, Philip E.; Jungwirth, Pavel

2015-01-01

Roč. 6, č. 9 (2015), s. 1563-1567 ISSN 1948-7185 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : ion pairing * molecular dynamics * neutron scattering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 8.539, year: 2015 http://pubs.acs.org/doi/pdf/10.1021/acs.jpclett.5b00060

Dynamical scenario of intermediary mass fragments formation in heavy ion collisions

International Nuclear Information System (INIS)

Ayik, S.; Belkacem, M.; Gregoire, C.; Stryjewski, J.; Suraud, E.

1989-01-01

We briefly remind the possible dynamical scenario of fragments formation in heavy-ion collisions at some tens fo MeV/A. We discuss how present day dynamical models can describe fragment formation. We next turn to the Boltzmann-Langevin formalism which provides a well defined theoretical framework for the understanding of the growing of the dynamical instabilities leading to multifragmentation. We present a first numerical solution of the Boltzmann-Langevin equation and we apply the formalism to the onset of multifragmentation of the 40 Ca + 40 Ca system between 20 and 60 MeV/A beam energy [fr

Dynamics of water and ions in clays of type montmorillonite by microscopic simulation and quasi-elastic neutron scattering

International Nuclear Information System (INIS)

Malikova, N.

2005-09-01

Montmorillonite clays in low hydration states, with Na + and Cs + compensating counter ions, are investigated by a combination of microscopic simulation and quasi-elastic neutron scattering to obtain information on the local structure and dynamics of water and ions in the interlayer. At first predictions of simulation into the dynamics of water and ions at elevate temperatures are shown (0 deg C 80 deg C, pertinent for the radioactive waste disposal scenario) Marked difference is observed between the modes of diffusion of the Na + and C + counter ions. In water dynamics, a significant step towards bulk water behaviour is seen on transition from the mono- to bilayer states. Secondly, a detailed comparison between simulation and quasi-elastic neutron scattering (Neutron Spin Echo and Time-of-Flight) regarding ambient temperature water dynamics is presented. Overall, the approaches are found to be in good agreement with each other and limitations of each of the methods are clearly shown. (author)

Lutetium(III) aqua ion: On the dynamical structure of the heaviest lanthanoid hydration complex

Energy Technology Data Exchange (ETDEWEB)

Sessa, Francesco; D’Angelo, Paola, E-mail: p.dangelo@uniroma1.it [Dipartimento di Chimica, Università di Roma “La Sapienza,” P. le A. Moro 5, 00185 Roma (Italy); Spezia, Riccardo [CNRS, UMR 8587, Laboratoire Analyse et Modelisation Pour la Biologie et l’Environnement, Université d’Evry Val d’Essonne, Blvd. F. Mitterrand, 91025 Evry Cedex (France)

2016-05-28

The structure and dynamics of the lutetium(III) ion in aqueous solution have been investigated by means of a polarizable force field molecular dynamics (MD). An 8-fold square antiprism (SAP) geometry has been found to be the dominant configuration of the lutetium(III) aqua ion. Nevertheless, a low percentage of 9-fold complexes arranged in a tricapped trigonal prism (TTP) geometry has been also detected. Dynamic properties have been explored by carrying out six independent MD simulations for each of four different temperatures: 277 K, 298 K, 423 K, 632 K. The mean residence time of water molecules in the first hydration shell at room temperature has been found to increase as compared to the central elements of the lanthanoid series in agreement with previous experimental findings. Water exchange kinetic rate constants at each temperature and activation parameters of the process have been determined from the MD simulations. The obtained structural and dynamical results suggest that the water exchange process for the lutetium(III) aqua ion proceeds with an associative mechanism, in which the SAP hydration complex undergoes temporary structural changes passing through a 9-fold TTP intermediate. Such results are consistent with the water exchange mechanism proposed for heavy lanthanoid atoms.

Dynamical effects prior to heavy ion fusion

International Nuclear Information System (INIS)

Mikhajlova, T.I.; Mikhajlov, I.N.; Molodtsova, I.V.; Di Toro, M.

2002-01-01

Dynamical effects in the initial phase of fusion reactions are studied following the evolution of two colliding 100 Mo ions. The role of elastic forces associated with the Fermi-surface deformation is shown by comparing the results obtained with and without taking the memory effects into account. The Bass barrier separating fused and scattered configurations and the lower bound for the extra push energy are estimated. Examples of cases are shown in which the excitation energy and deformation dependence of the friction parameter are fictitious and simulate the effects of collective motion related with the Fermi-surface deformations

Resonant electron capture by aspartame and aspartic acid molecules.

Science.gov (United States)

Muftakhov, M V; Shchukin, P V

2016-12-30

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

Mitochondrial membranes with mono- and divalent salt: changes induced by salt ions on structure and dynamics

DEFF Research Database (Denmark)

Pöyry, Sanja; Róg, Tomasz; Karttunen, Mikko

2009-01-01

We employ atomistic simulations to consider how mono- (NaCl) and divalent (CaCl(2)) salt affects properties of inner and outer membranes of mitochondria. We find that the influence of salt on structural properties is rather minute, only weakly affecting lipid packing, conformational ordering......, and membrane electrostatic potential. The changes induced by salt are more prominent in dynamical properties related to ion binding and formation of ion-lipid complexes and lipid aggregates, as rotational diffusion of lipids is slowed down by ions, especially in the case of CaCl(2). In the same spirit, lateral...... diffusion of lipids is slowed down rather considerably for increasing concentration of CaCl(2). Both findings for dynamic properties can be traced to the binding of ions with lipid head groups and the related changes in interaction patterns in the headgroup region, where the binding of Na(+) and Ca(2+) ions...

Mechanisms of Acceleration and Retardation of Water Dynamics by Ions

Czech Academy of Sciences Publication Activity Database

Stirnemann, G.; Wernersson, Erik; Jungwirth, Pavel; Laage, D.

2013-01-01

Roč. 135, č. 32 (2013), s. 11824-11831 ISSN 0002-7863 R&D Projects: GA ČR GBP208/12/G016 Grant - others:European Research Council(XE) FP7-279977 Institutional support: RVO:61388963 Keywords : ions * water * molecular dynamics * NMR * IR Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 11.444, year: 2013

Dynamic behavior of IREB in a collective ion acceleration experiment

International Nuclear Information System (INIS)

Fine, T.A.; Rhee, M.J.

1989-01-01

The authors report an experimental study of dynamic behavior of net current in conjunction with collective ion acceleration. In the presence of neutral gas, either puffed in or released from the anode foil, the IREB injected is subject to the charge and current neutralizations, resulting in a complicated time and space dependent beam distribution in the drift tube. To investigate the dynamic behavior of the current in the drift tube, typically a 0.5 MeV, 70 kA, 100 ns electron beam of 2.54 cm diam is injected through a foil anode into a drift tube of 15 cm diam. Reproducibility of experiment was improved by using a specially designed anode system with a foil changer which allowed the production of many shots of high current electron beam without disturbing the vacuum condition. The net currents were measured by a Rogowski coil built in the anode system, and a movable Faraday cup along the drift tube. The ions accelerated were diagnosed mainly by a Thomson spectrometer system placed at the end of the drift tube

Dynamic rayed aurora and enhanced ion-acoustic radar echoes

Directory of Open Access Journals (Sweden)

E. M. Blixt

2005-01-01

Full Text Available The generation mechanism for naturally enhanced ion-acoustic echoes is still debated. One important issue is how these enhancements are related to auroral activity. All events of enhanced ion-acoustic echoes observed simultaneously with the EISCAT Svalbard Radar (ESR and with high-resolution narrow field-of-view auroral imagers have been collected and studied. Characteristic of all the events is the appearance of very dynamic rayed aurora, and some of the intrinsic features of these auroral displays are identified. Several of these identified features are directly related to the presence of low energy (10-100eV precipitating electrons in addition to the higher energy population producing most of the associated light. The low energy contribution is vital for the formation of the enhanced ion-acoustic echoes. We argue that this type of aurora is sufficient for the generation of naturally enhanced ion-acoustic echoes. In one event two imagers were used to observe the auroral rays simultaneously, one from the radar site and one 7km away. The data from these imagers shows that the auroral rays and the strong backscattering filaments (where the enhanced echoes are produced are located on the same field line, which is in contrast to earlier statements in the litterature that they should be separated.

Nuclear muon capture

CERN Document Server

Mukhopadhyay, N C

1977-01-01

Our present knowledge of the nuclear muon capture reactions is surveyed. Starting from the formation of the muonic atom, various phenomena, having a bearing on the nuclear capture, are reviewed. The nuclear reactions are then studied from two angles-to learn about the basic muon+nucleon weak interaction process, and to obtain new insights on the nuclear dynamics. Future experimental prospects with the newer generation muon 'factories' are critically examined. Possible modification of the muon+nucleon weak interaction in complex nuclei remains the most important open problem in this field. (380 refs).

Nano-memory-element applications of carbon nanocapsule encapsulating potassium ions: molecular dynamics study

International Nuclear Information System (INIS)

Kang, Jeong Won; Hwang, Ho Jung

2004-01-01

We investigated the internal dynamics of ionic fluidic shuttle memory elements consisting of potassium ions encapsulated in C 640 nanocapsules. The systems proposed were the encapsulated-ion shuttle memory devices such as (13 K + ) at C 640 , (3 K + -C 60 -2 K + ) at C 640 and (5 K + -C 60 ) at C 640 . The energetics and the operating responses of ionic fluidic shuttle memory devices, such as transitions between the two states of the C 640 capsule, were examined by using classical molecular dynamics simulations of the shuttle media in the C 640 capsule under external force fields. The operating force fields for stable operations of the shuttle memory device were investigated.

Cross sections for one-electron capture by highly stripped ions of Be, B and C from H2 and Ar below 10 keV

International Nuclear Information System (INIS)

Takagi, S.; Ohtani, S.; Kadota, K.; Fujita, J.

1982-03-01

Cross sections for one-electron capture by highly stripped ions of Be, B and C from H 2 and Ar are measured at low energies below 10 keV. The cross sections are nearly independent of the collision energy investigated. The distinct oscillation with incident ionic charge g in the cross sections are observed. (author)

Spectroscopic investigation of the charge dynamics of heavy ions penetrating solid and gaseous targets

International Nuclear Information System (INIS)

Korostiy, S.

2007-01-01

This thesis presents the study of the slowing down process of fast heavy ions inside matter. In the framework of this research, the influence of the target density on the stopping process is investigated. Experiments on the interaction of 48 Ca 6+ - 48 Ca 10+ and 26 Mg 5+ ion beams with initial energies of 11.4 MeV/u and 5.9 MeV/u with solid and gaseous targets have been carried out. A novel diagnostic method, X-ray spectroscopy of K-shell projectile radiation, is used to determine the ion charge state in relation to its velocity during the penetration of fast heavy ions inside the stopping material. A spatially resolved analysis of the projectile and target radiation in solids is achieved for the first time. The application of low-density silica aerogels as stopping media provided a stretching of the ion stopping length by 20 - 100 times in comparison with solid quartz. The Doppler Effect observed on the projectile K-shell spectra is used to calculate the ion velocity in dependence on the ion penetration depth in the target material. A comparative analysis of K α spectra of fast heavy ions is performed in solid (silica aerogels) and gaseous targets (Ar and Ne gases) at the same ion energy. It is shown that the dominant role of collisions in dense matter leads to an increase of the effective ionization cross section at high ion velocity and suppression of the electron capture to the projectile ion excited states at low ion velocity. As a result, an increase of the ion charge state in dense matter is observed. The experimentally detected effects are interpreted with numerical calculations of the projectile population kinetics, which are in good agreement with measurements. (orig.)

Spectroscopic investigation of the charge dynamics of heavy ions penetrating solid and gaseous targets

Energy Technology Data Exchange (ETDEWEB)

Korostiy, S

2007-01-15

This thesis presents the study of the slowing down process of fast heavy ions inside matter. In the framework of this research, the influence of the target density on the stopping process is investigated. Experiments on the interaction of {sup 48}Ca{sup 6+}-{sup 48}Ca{sup 10+} and {sup 26}Mg{sup 5+} ion beams with initial energies of 11.4 MeV/u and 5.9 MeV/u with solid and gaseous targets have been carried out. A novel diagnostic method, X-ray spectroscopy of K-shell projectile radiation, is used to determine the ion charge state in relation to its velocity during the penetration of fast heavy ions inside the stopping material. A spatially resolved analysis of the projectile and target radiation in solids is achieved for the first time. The application of low-density silica aerogels as stopping media provided a stretching of the ion stopping length by 20 - 100 times in comparison with solid quartz. The Doppler Effect observed on the projectile K-shell spectra is used to calculate the ion velocity in dependence on the ion penetration depth in the target material. A comparative analysis of K{sub {alpha}} spectra of fast heavy ions is performed in solid (silica aerogels) and gaseous targets (Ar and Ne gases) at the same ion energy. It is shown that the dominant role of collisions in dense matter leads to an increase of the effective ionization cross section at high ion velocity and suppression of the electron capture to the projectile ion excited states at low ion velocity. As a result, an increase of the ion charge state in dense matter is observed. The experimentally detected effects are interpreted with numerical calculations of the projectile population kinetics, which are in good agreement with measurements. (orig.)

State-selective electron capture

International Nuclear Information System (INIS)

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

1988-01-01

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

A Collimation Scheme for Ions Changing Charge State in the LEIR Ring

CERN Document Server

Pasternak, Jaroslaw; Carli, Christian; Chanel, Michel; Mahner, Edgar

2005-01-01

Avalanche-like pressure rise and an associated decrease of the beam life-time, caused by (i) beam loss due to charge exchange interactions with rest gas molecules and (ii) electron capture from the electron beam of the electron cooler and (iii) ion impact induced outgassing, is a potential limitation for heavy ion accelerators. The vacuum system of the LEIR ring as to be upgraded to reach the dynamical vacuum pressure in the low 10-12 Torr range necessary to reach design performance. A collimation system to intercept lost ions by absorber blocks made of low beam-induced outgassing material will be installed. This paper reviews the collimation scheme and simulations of beam loss patterns around the ring.

Bistable dynamics underlying excitability of ion homeostasis in neuron models.

Directory of Open Access Journals (Sweden)

Niklas Hübel

2014-05-01

Full Text Available When neurons fire action potentials, dissipation of free energy is usually not directly considered, because the change in free energy is often negligible compared to the immense reservoir stored in neural transmembrane ion gradients and the long-term energy requirements are met through chemical energy, i.e., metabolism. However, these gradients can temporarily nearly vanish in neurological diseases, such as migraine and stroke, and in traumatic brain injury from concussions to severe injuries. We study biophysical neuron models based on the Hodgkin-Huxley (HH formalism extended to include time-dependent ion concentrations inside and outside the cell and metabolic energy-driven pumps. We reveal the basic mechanism of a state of free energy-starvation (FES with bifurcation analyses showing that ion dynamics is for a large range of pump rates bistable without contact to an ion bath. This is interpreted as a threshold reduction of a new fundamental mechanism of ionic excitability that causes a long-lasting but transient FES as observed in pathological states. We can in particular conclude that a coupling of extracellular ion concentrations to a large glial-vascular bath can take a role as an inhibitory mechanism crucial in ion homeostasis, while the Na⁺/K⁺ pumps alone are insufficient to recover from FES. Our results provide the missing link between the HH formalism and activator-inhibitor models that have been successfully used for modeling migraine phenotypes, and therefore will allow us to validate the hypothesis that migraine symptoms are explained by disturbed function in ion channel subunits, Na⁺/K⁺ pumps, and other proteins that regulate ion homeostasis.

Coincident Auger electron and recoil ion momentum spectroscopy for low-energy ion-atom collisions

International Nuclear Information System (INIS)

Laurent, G.; Tarisien, M.; Flechard, X.; Jardin, P.; Guillaume, L.; Sobocinski, P.; Adoui, L.; Bordenave-Montesquieu, A.; Bordenave-Montesquieu, D.; Chesnel, J.-Y.; Fremont, F.; Hennecart, D.; Lienard, E.; Maunoury, L.; Moretto-Capelle, P.; Cassimi, A.

2003-01-01

The recoil ion momentum spectroscopy (RIMS) method combined with the detection of Auger electrons has been used successfully to analyse double electron capture following O 6+ + He collisions at low impact velocities. Although RIMS and Auger spectroscopies are known to be efficient tools to obtain details on the primary processes occurring during the collision, the conjunction of both techniques provides new insights on the electron capture process. In the present experiment, triple coincidence detection of the scattered projectile, the target recoil ion and the Auger electron allows for a precise identification of the doubly excited states O 4+ (1s 2 nln ' l ' ) populated after double electron-capture events

Hard photons a probe of the heavy ion collision dynamics

International Nuclear Information System (INIS)

Schutz, Y.

1994-01-01

Heavy-ion collisions have proven to be a unique tool to study the nucleus in extreme states, with values of energy, spin and isospin far away from those encountered in the nucleus in its ground state. Heavy-ion collisions provide also the only mean to form and study in the laboratory nuclear matter under conditions of density and temperature which could otherwise only be found in stellar objects like neutron stars and super-novae. the goal of such studies is to establish the equation of state of nuclear matter and the method consist in searching the collective behaviour in which heavy-ion collisions differ from a superposition of many nucleon-nucleon collisions. Among the various probes of collective effects, like flow, multifragmentation, or subthreshold particles, we have selected hard photons because they provide, together with dileptons, the only unperturbed probe of a phase of the collision well localized in space and time. The origin of hard photons, defined as the photons building up the spectrum beyond the energy of the giant dipole resonance (E γ > 30∼MeV), is attributed predominantly to the bremsstrahlung radiation emitted incoherently in individual neutron-proton collisions. Their energy reflects the combination of the beam momentum and the momenta induced by the Fermi motion of the nucleons within the collision zone. Therefore, at intermediate energies, hard photons probe the dynamical phase space distribution of participant nucleons and they convey information on the densities reached in heavy-ion collisions, the size and life time of the dense photon source and the compressibility of nuclear matter. The techniques we have developed include intensity interferometry and exclusive measurements scanning with high resolution the whole range of impact parameters. The interpretation of our data is guided by dynamical phase space calculations of the BUU type

Analysis methods for fast impurity ion dynamics data

International Nuclear Information System (INIS)

Den Hartog, D.J.; Almagri, A.F.; Prager, S.C.; Fonck, R.J.

1994-08-01

A high resolution spectrometer has been developed and used on the MST reversed-field pinch (RFP) to measure passively impurity ion temperatures and flow velocities with 10 μs temporal resolution. Such measurements of MHD-scale fluctuations are particularly relevant in the RFP because the flow velocity fluctuation induced transport of current (the ''MHD dynamo'') may produce the magnetic field reversal characteristic of an RFP. This instrument will also be used to measure rapid changes in the equilibrium flow velocity, such as occur during locking and H-mode transition. The precision of measurements made to date is <0.6 km/s. The authors are developing accurate analysis techniques appropriate to the reduction of this fast ion dynamics data. Moment analysis and curve-fitting routines have been evaluated for noise sensitivity and robustness. Also presented is an analysis method which correctly separates the flux-surface average of the correlated fluctuations in u and B from the fluctuations due to rigid shifts of the plasma column

Multicharged Ion-induced simple molecule fragmentation dynamics; Dynamique de la fragmentation de molecules simples induite par impact d'ion multicharge

Energy Technology Data Exchange (ETDEWEB)

Tarisien, M

2003-10-01

The aim of this work is to study the dynamics of swift multicharged ion-induced fragmentation of diatomic (CO) and triatomic (CO{sub 2}) molecules. Performed at the GANIL facility, this study used the Recoil Ion Momentum Spectroscopy technique (RIMS), which consists of a time-of-flight mass spectrometer, coupled with a multi-hit capability position sensitive detector (delay line anode). The high-resolution measurement of the kinetic energy distribution released (KER) during the CO fragmentation points out the limitation of the Coulomb Explosion Model, revealing, for example, the di-cation CO{sub 2}{sup +} electronic state contribution in the case of C{sup +}/O{sup +} fragmentation pathway. Furthermore, the multi-ionization cross section dependence with the orientation of the internuclear axis of CO is compared with a geometrical model calculation. Finally, different behaviours are observed for the dissociation dynamics of a triatomic molecule (CO{sub 2}). While triple ionization leads mainly to a synchronous concerted fragmentation dynamics, a weak fraction of dissociating molecule follows a sequential dynamics involving CO{sub 2}{sup +} metastable states. In the case of double ionization, (CO{sub 2}){sup 2+} di-cation dissociation dynamics is asynchronously concerted and has been interpreted using a simple model involving an asymmetrical vibration of the molecule. (author)

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

International Nuclear Information System (INIS)

Puerta, J.; Huber, B.A.

1985-03-01

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

Effects of Energetic Ion Outflow on Magnetospheric Dynamics

Science.gov (United States)

Kistler, L. M.; Mouikis, C.; Lund, E. J.; Menz, A.; Nowrouzi, N.

2016-12-01

There are two dominant regions of energetic ion outflow: the nightside auroral region and the dayside cusp. Processes in these regions can accelerate ions up to keV energies. Outflow from the nightside has direct access to the plasma sheet, while outflow from the cusp is convected over the polar cap and into the lobes. The cusp population can enter the plasma sheet from the lobe, with higher energy ions entering further down the tail than lower energy ions. During storm times, the O+ enhanced plasma sheet population is convected into the inner magnetosphere. The plasma that does not get trapped in the inner magnetosphere convects to the magnetopause where reconnection is taking place. An enhanced O+ population can change the plasma mass density, which may have the effect of decreasing the reconnection rate. In addition O+ has a larger gyroradius than H+ at the same velocity or energy. Because of this, there are larger regions where the O+ is demagnetized, which can lead to larger acceleration because the O+ can move farther in the direction of the electric field. In this talk we will review results from Cluster, Van Allen Probes, and MMS, on how outflow from the two locations affects magnetospheric dynamics. We will discuss whether enhanced O+ from either population has an effect on the reconnection rate in the tail or at the magnetopause. We will discuss how the two populations impact the inner magnetosphere during storm times. And finally, we will discuss whether either population plays a role in triggering substorms, particularly during sawtooth events.

Phase transition dynamics in ultrarelativistic heavy ion collisions

International Nuclear Information System (INIS)

Csernai, L.P.; Zabrodin, E.E.; Moscow State Univ.

1993-01-01

We investigate various problems related to the dynamics of a first-order phase transition from quarkgluon plasma to hadronic matter in ultra-relativistic heavy ion collisions. These include nucleation, growth and fusion of hadronic bubbles in either the Bjorken longitudinal hydrodynamic expansion model or the Cooper-Frye-Schonberg spherical hydrodynamic expansion model. With reasonable input parameters the conversion of one phase into the other is relatively close to the idealized adiabatic Maxwell construction, although one can choose parameters such that the conversion is strongly out of equilibrium. (orig.)

Phase transition dynamics in ultrarelativistic heavy ion collisions

International Nuclear Information System (INIS)

Csernai, L.P.; Kapusta, J.I.; Kluge, Gy.; Hungarian Academy of Sciences, Budapest; Zabrodin, E.E.; Moskovskij Gosudarstvennyj Univ., Moscow

1992-12-01

Various problems were investigated concerning the dynamics of a first-order phase transition from quark-gluon plasma to hadronic matter in ultra-relativistic heavy ion collisions. These include nucleation, growth and fusion of hadronic bubbles in either the Bjorken longitudinal hydrodynamic expansion model or the Cooper-Frye-Schonberg spherical hydrodynamic expansion model. With reasonable input parameters the conversion of one phase into the other is relatively close to the idealized adiabatic Maxwell construction, although one can choose parameters such that the conversion is strongly out of equilibrium. (author) 10 refs.; 7 figs

Flexible dynamic operation of solar-integrated power plant with solvent based post-combustion carbon capture (PCC) process

International Nuclear Information System (INIS)

Qadir, Abdul; Sharma, Manish; Parvareh, Forough; Khalilpour, Rajab; Abbas, Ali

2015-01-01

Highlights: • Flexible operation of power and PCC plant may significantly increase operational revenue. • Higher optimal carbon capture rates observed with solar thermal energy input. • Solar thermal repowering of the power plant provides highest net revenue. • Constant optimal capture rate observed for one of the flexible operation cases. • Up to 42% higher revenue generation observed between two cases with solar input. - Abstract: This paper examines flexible operation of solvent-based post-combustion carbon capture (PCC) for the reduction of power plant carbon emissions while minimizing revenue loss due to the reduced power plant electricity output. The study is conducted using a model superstructure enveloping three plants; a power plant, a PCC plant and a solar thermal field where the power plant and PCC plant are operated flexibly under the influence of hourly electricity market and weather conditions. Reduced (surrogate) models for the reboiler duty and auxiliary power requirement for the carbon capture plant are generated and applied to simulate and compare four cases, (A) power plant with PCC, (B) power plant with solar assisted PCC, (C) power plant with PCC and solar repowering – variable net electricity output and (D) power plant with PCC and solar repowering – fixed net electricity output. Such analyses are conducted under dynamic conditions including power plant part-load operation while varying the capture rate to optimize the revenue of the power plant. Each case was simulated with a lower carbon price of $25/tonne-CO 2 and a higher price of $50/tonne-CO 2 . The comparison of cases B–D found that optimal revenue generation for case C can be up to 42% higher than that of solar-assisted PCC (case B). Case C is found to be the most profitable with the lowest carbon emissions intensity and is found to exhibit a constant capture rate for both carbon prices. The optimal revenue for case D is slightly lower than case C for the lower carbon

Incremental learning for automated knowledge capture

Energy Technology Data Exchange (ETDEWEB)

Benz, Zachary O. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Basilico, Justin Derrick [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Davis, Warren Leon [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dixon, Kevin R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jones, Brian S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Nathaniel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wendt, Jeremy Daniel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2013-12-01

People responding to high-consequence national-security situations need tools to help them make the right decision quickly. The dynamic, time-critical, and ever-changing nature of these situations, especially those involving an adversary, require models of decision support that can dynamically react as a situation unfolds and changes. Automated knowledge capture is a key part of creating individualized models of decision making in many situations because it has been demonstrated as a very robust way to populate computational models of cognition. However, existing automated knowledge capture techniques only populate a knowledge model with data prior to its use, after which the knowledge model is static and unchanging. In contrast, humans, including our national-security adversaries, continually learn, adapt, and create new knowledge as they make decisions and witness their effect. This artificial dichotomy between creation and use exists because the majority of automated knowledge capture techniques are based on traditional batch machine-learning and statistical algorithms. These algorithms are primarily designed to optimize the accuracy of their predictions and only secondarily, if at all, concerned with issues such as speed, memory use, or ability to be incrementally updated. Thus, when new data arrives, batch algorithms used for automated knowledge capture currently require significant recomputation, frequently from scratch, which makes them ill suited for use in dynamic, timecritical, high-consequence decision making environments. In this work we seek to explore and expand upon the capabilities of dynamic, incremental models that can adapt to an ever-changing feature space.

Nuclear structure studies with low-energy light ions: fundamental and applied

International Nuclear Information System (INIS)

Mazumdar, I.

2016-01-01

Studies in low and medium energy nuclear physics have been dominated by heavy-ion induced reactions for last five decades. Heavy-ion induced nuclear reactions have enriched our knowledge of the structural evolutions and intricacies of reaction dynamics of the nuclear many-body systems. However, the emergence and rise of heavy-ion physics have seen a general decline in studies with low- and medium-energy light-ion beams. The harsh reality of dwindling number of low-energy light ion facilities adversely affect research in nuclear physics. Very low-energy and high current light-ion facilities immediately conjures up in our minds the studies in nuclear astrophysics. Measurements of light-ion capture cross sections and astrophysical S factors are the major themes of research at most of the light-ion facilities. However, the importance low energy light-ion beams is multifarious. A variety of measurements providing vital support and inputs to heavy-ion research can only be carried out at the low-energy, light-ion facilities. Light-ion beams are also useful for generation of mono-energetic neutron beams. In this talk I will draw from some of our recent measurements to show the importance of light-ion beams in nuclear astrophysics and also in applied nuclear physics. (author)

Transverse acceptance calculation for continuous ion beam injection into the electron beam ion trap charge breeder of the ReA post-accelerator

Energy Technology Data Exchange (ETDEWEB)

Kittimanapun, K., E-mail: kritsadak@slri.or.th [National Superconducting Cyclotron Laboratory (NSCL), Michigan State University (MSU), 640 S. Shaw Lane, East Lansing, Michigan 48824 (United States); Synchrotron Light Research Institute (SLRI), 111 University Avenue, Muang District, Nakhon Ratchasima, 30000 (Thailand); Baumann, T.M.; Lapierre, A.; Schwarz, S. [National Superconducting Cyclotron Laboratory (NSCL), Michigan State University (MSU), 640 S. Shaw Lane, East Lansing, Michigan 48824 (United States); Bollen, G. [National Superconducting Cyclotron Laboratory (NSCL), Michigan State University (MSU), 640 S. Shaw Lane, East Lansing, Michigan 48824 (United States); Facility for Rare Isotope Beams (FRIB), Michigan State University, 640 S. Shaw Lane, East Lansing, Michigan 48824 (United States)

2015-11-11

The ReA post-accelerator at the National Superconducting Cyclotron Laboratory (NSCL) employs an electron beam ion trap (EBIT) as a charge breeder. A Monte-Carlo simulation code was developed to calculate the transverse acceptance phase space of the EBIT for continuously injected ion beams and to determine the capture efficiency in dependence of the transverse beam emittance. For this purpose, the code records the position and time of changes in charge state of injected ions, leading either to capture or loss of ions. To benchmark and validate the code, calculated capture efficiencies were compared with results from a geometrical model and measurements. The results of the code agree with the experimental findings within a few 10%. The code predicts a maximum total capture efficiency of 50% for EBIT parameters readily achievable and an efficiency of up to 80% for an electron beam current density of 1900 A/cm{sup 2}.

Energy and material balance of CO2 capture from ambient air.

Science.gov (United States)

Zeman, Frank

2007-11-01

Current Carbon Capture and Storage (CCS) technologies focus on large, stationary sources that produce approximately 50% of global CO2 emissions. We propose an industrial technology that captures CO2 directly from ambient air to target the remaining emissions. First, a wet scrubbing technique absorbs CO2 into a sodium hydroxide solution. The resultant carbonate is transferred from sodium ions to calcium ions via causticization. The captured CO2 is released from the calcium carbonate through thermal calcination in a modified kiln. The energy consumption is calculated as 350 kJ/mol of CO2 captured. It is dominated by the thermal energy demand of the kiln and the mechanical power required for air movement. The low concentration of CO2 in air requires a throughput of 3 million cubic meters of air per ton of CO2 removed, which could result in significant water losses. Electricity consumption in the process results in CO2 emissions and the use of coal power would significantly reduce to net amount captured. The thermodynamic efficiency of this process is low but comparable to other "end of pipe" capture technologies. As another carbon mitigation technology, air capture could allow for the continued use of liquid hydrocarbon fuels in the transportation sector.

CAPTURE OF TROJANS BY JUMPING JUPITER

International Nuclear Information System (INIS)

Nesvorný, David; Vokrouhlický, David; Morbidelli, Alessandro

2013-01-01

Jupiter Trojans are thought to be survivors of a much larger population of planetesimals that existed in the planetary region when planets formed. They can provide important constraints on the mass and properties of the planetesimal disk, and its dispersal during planet migration. Here, we tested a possibility that the Trojans were captured during the early dynamical instability among the outer planets (aka the Nice model), when the semimajor axis of Jupiter was changing as a result of scattering encounters with an ice giant. The capture occurs in this model when Jupiter's orbit and its Lagrange points become radially displaced in a scattering event and fall into a region populated by planetesimals (that previously evolved from their natal transplanetary disk to ∼5 AU during the instability). Our numerical simulations of the new capture model, hereafter jump capture, satisfactorily reproduce the orbital distribution of the Trojans and their total mass. The jump capture is potentially capable of explaining the observed asymmetry in the number of leading and trailing Trojans. We find that the capture probability is (6-8) × 10 –7 for each particle in the original transplanetary disk, implying that the disk contained (3-4) × 10 7 planetesimals with absolute magnitude H disk ∼ 14-28 M Earth , is consistent with the mass deduced from recent dynamical simulations of the planetary instability.

Ion beam dynamics in the acceleration region of the Vincy Cyclotron

International Nuclear Information System (INIS)

Tomic, S.; Samsonov, E.

1998-01-01

Modern concept of heavy ion cyclotrons assumes a tendency of decreasing the gaps between magnet poles, enabling better efficiency of the magnetic field circuit. This restricts possible solutions of acceleration structure and imposes the necessity of installing the dees in valleys of magnetic structures. This approach, which is accepted in the VINCY Cyclotron, requires a detailed study of the ion beam dynamics in the acceleration region. Consequently, we analyzed ion beams with eta = 1,05 and 0.25 in radial and axial phase space. Also, the energy spread in emittances and the influence of the first harmonic of the magnetic field on the radial betatron oscillations are discussed. The transformation of coherent into incoherent radial oscillations as well as the effect to radial off-centering on the beam vertical size at Walkinshaw resonance location, is pointed out (author)

Fast calculator for X-ray emission due to Radiative Recombination and Radiative Electron Capture in relativistic heavy-ion atom collisions

Science.gov (United States)

Herdrich, M. O.; Weber, G.; Gumberidze, A.; Wu, Z. W.; Stöhlker, Th.

2017-10-01

In experiments with highly charged, fast heavy ions the Radiative Recombination (RR) and Radiative Electron Capture (REC) processes have significant cross sections in an energy range of up to a few GeV / u . They are some of the most important charge changing processes in collisions of heavy ions with atoms and electrons, leading to the emission of a photon along with the formation of the ground and excited atomic states. Hence, for the understanding and planning of experiments, in particular for X-ray spectroscopy studies, at accelerator ring facilities, such as FAIR, it is crucial to have a good knowledge of these cross sections and the associated radiation characteristics. In the frame of this work a fast calculator, named RECAL, for the RR and REC process is presented and its capabilities are demonstrated with the analysis of a recently conducted experiment at the Experimental Storage Ring (ESR) at the GSI Helmholtz Center for Heavy Ion Research in Darmstadt, Germany. A method is presented to determine unknown X-ray emission cross sections via normalization of the recorded spectra to REC cross sections calculated by RECAL.

Coincident Auger electron and recoil ion momentum spectroscopy for low-energy ion-atom collisions

Energy Technology Data Exchange (ETDEWEB)

Laurent, G. E-mail: glaurent@ganil.fr; Tarisien, M.; Flechard, X.; Jardin, P.; Guillaume, L.; Sobocinski, P.; Adoui, L.; Bordenave-Montesquieu, A.; Bordenave-Montesquieu, D.; Chesnel, J.-Y.; Fremont, F.; Hennecart, D.; Lienard, E.; Maunoury, L.; Moretto-Capelle, P.; Cassimi, A

2003-05-01

The recoil ion momentum spectroscopy (RIMS) method combined with the detection of Auger electrons has been used successfully to analyse double electron capture following O{sup 6+} + He collisions at low impact velocities. Although RIMS and Auger spectroscopies are known to be efficient tools to obtain details on the primary processes occurring during the collision, the conjunction of both techniques provides new insights on the electron capture process. In the present experiment, triple coincidence detection of the scattered projectile, the target recoil ion and the Auger electron allows for a precise identification of the doubly excited states O{sup 4+} (1s{sup 2}nln{sup '}l{sup '}) populated after double electron-capture events.

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

DEFF Research Database (Denmark)

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

2008-01-01

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

Production and sympathetic cooling of complex molecular ions

Energy Technology Data Exchange (ETDEWEB)

Zhang, Chaobo

2008-06-24

This thesis reports on experimental and theoretical studies of the sympathetic cooling of complex molecular ions demonstrating that this general method for cooling atomic and molecular ions is reliable and efficient. For this purpose, complex molecular ions and barium ions have been confined simultaneously in a linear Paul trap. The complex molecular ions are generated in an electrospray ionization system and transferred to the trap via a 2 m long octopole ion guide. These molecular ions are pre-cooled by room temperature helium buffer gas so that they can be captured by the trap. The atomic barium ions are loaded from a barium evaporator oven and are laser-cooled by a 493 nm cooling laser and a 650 nm repumping laser. Due to the mutual Coulomb interaction among these charged particles, the kinetic energy of the complex molecular ions can be reduced significantly. In our experiments we have demonstrated the sympathetic cooling of various molecules (CO{sub 2}, Alexa Fluor 350, glycyrrhetinic acid, cytochrome c) covering a wide mass range from a few tens to 13000 amu. In every case the molecular ions could be cooled down to millikelvin temperatures. Photo-chemical reactions of the {sup 138}Ba{sup +} ions in the ({sup 2}P{sub 1/2}) excited state with gases such as O{sub 2}, CO{sub 2}, or N{sub 2}O, could be observed. If the initial {sup 138}Ba{sup +} ion ensemble is cold, the produced {sup 138}BaO{sup +} ions are cold as well, with a similar temperature as the laser-cooled barium ions (a few tens of millikelvin). The back-reaction of {sup 138}BaO{sup +} ions with neutral CO to {sup 138}Ba{sup +} is possible and was observed in our experiments as well. A powerful molecular dynamics (MD) simulation program has been developed. With this program dynamic properties of ion ensembles, such as sympathetic interactions or heating effects, have been investigated and experimental results have been analyzed to obtain, for example, ion numbers and temperatures. Additionally, the

Production and sympathetic cooling of complex molecular ions

International Nuclear Information System (INIS)

Zhang, Chaobo

2008-01-01

This thesis reports on experimental and theoretical studies of the sympathetic cooling of complex molecular ions demonstrating that this general method for cooling atomic and molecular ions is reliable and efficient. For this purpose, complex molecular ions and barium ions have been confined simultaneously in a linear Paul trap. The complex molecular ions are generated in an electrospray ionization system and transferred to the trap via a 2 m long octopole ion guide. These molecular ions are pre-cooled by room temperature helium buffer gas so that they can be captured by the trap. The atomic barium ions are loaded from a barium evaporator oven and are laser-cooled by a 493 nm cooling laser and a 650 nm repumping laser. Due to the mutual Coulomb interaction among these charged particles, the kinetic energy of the complex molecular ions can be reduced significantly. In our experiments we have demonstrated the sympathetic cooling of various molecules (CO 2 , Alexa Fluor 350, glycyrrhetinic acid, cytochrome c) covering a wide mass range from a few tens to 13000 amu. In every case the molecular ions could be cooled down to millikelvin temperatures. Photo-chemical reactions of the 138 Ba + ions in the ( 2 P 1/2 ) excited state with gases such as O 2 , CO 2 , or N 2 O, could be observed. If the initial 138 Ba + ion ensemble is cold, the produced 138 BaO + ions are cold as well, with a similar temperature as the laser-cooled barium ions (a few tens of millikelvin). The back-reaction of 138 BaO + ions with neutral CO to 138 Ba + is possible and was observed in our experiments as well. A powerful molecular dynamics (MD) simulation program has been developed. With this program dynamic properties of ion ensembles, such as sympathetic interactions or heating effects, have been investigated and experimental results have been analyzed to obtain, for example, ion numbers and temperatures. Additionally, the feasibility of nondestructive spectroscopy via an optical dipole excitation

Electron capture by highly stripped ions

International Nuclear Information System (INIS)

Greenland, P.T.

1981-06-01

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

Highly Sensitive and Selective Potassium Ion Detection Based on Graphene Hall Effect Biosensors

Directory of Open Access Journals (Sweden)

Xiangqi Liu

2018-03-01

Full Text Available Potassium (K+ ion is an important biological substance in the human body and plays a critical role in the maintenance of transmembrane potential and hormone secretion. Several detection techniques, including fluorescent, electrochemical, and electrical methods, have been extensively investigated to selectively recognize K+ ions. In this work, a highly sensitive and selective biosensor based on single-layer graphene has been developed for K+ ion detection under Van der Pauw measurement configuration. With pre-immobilization of guanine-rich DNA on the graphene surface, the graphene devices exhibit a very low limit of detection (≈1 nM with a dynamic range of 1 nM–10 μM and excellent K+ ion specificity against other alkali cations, such as Na+ ions. The origin of K+ ion selectivity can be attributed to the fact that the formation of guanine-quadruplexes from guanine-rich DNA has a strong affinity for capturing K+ ions. The graphene-based biosensors with improved sensing performance for K+ ion recognition can be applied to health monitoring and early disease diagnosis.

Atomic Data for Neutron-capture Elements I. Photoionization and Recombination Properties of Low-charge Selenium Ions

Science.gov (United States)

Sterling, N. C.; Witthoeft, Michael

2011-01-01

We present multi-configuration Breit-Pauli AUTOSTRUCTURE calculations of distorted-wave photoionization (PI) cross sections. and total and partial final-state resolved radiative recombination (RR) and dielectronic recombination (DR) rate coefficients for the first six ions of the trans-iron element Se. These calculations were motivated by the recent detection of Se emission lines in a large number of planetary nebulae. Se is a potentially useful tracer of neutron-capture nucleosynthesis. but accurate determinations of its abundance in photoionized nebulae have been hindered by the lack of atomic data governing its ionization balance. Our calculations were carried out in intermediate coupling with semi re1ativistic radial wavefunctions. PI and recombination data were determined for levels within the ground configuration of each ion, and experimental PI cross-section measurements were used to benchmark our results. For DR, we allowed (Delta)n = 0 core excitations, which are important at photoionized plasma temperatures. We find that DR is the dominant recombination process for each of these Se ions at temperatures representative of photoionized nebulae (approx.10(exp 4) K). In order to estimate the uncertainties of these data, we compared results from three different configuration-interaction expansions for each ion, and also tested the sensitivity of the results to the radial scaling factors in the structure calculations. We find that the internal uncertainties are typically 30-50% for the direct PI cross sections and approx.10% for the computed RR rate coefficients, while those for low-temperature DR can be considerably larger (from 15-30% up to two orders of magnitude) due to the unknown energies of near-threshold autoionization resonances. These data are available at the CDS, and fitting coefficients to the total RR and DR rate coefficients are presented. The results are suitable for incorporation into photoionization codes used to numerically simulate

Circular Orbit Target Capture Using Space Tether-Net System

Directory of Open Access Journals (Sweden)

Guang Zhai

2013-01-01

Full Text Available The space tether-net system for on-orbit capture is proposed in this paper. In order to research the dynamic behaviors during system deployment, both free and nonfree deployment dynamics in circular orbit are developed; the system motion with respect to Local Vertical and Local Horizontal frame is also researched with analysis and simulation. The results show that in the case of free deployment, the capture net follows curve trajectories due to the relative orbit dynamic perturbation, and the initial deployment velocities are planned by state transformation equations for static and floating target captures; in the case of non-free deployment, the system undergoes an altitude libration along the Local Vertical, and the analytical solutions that describe the attitude libration are obtained by using variable separation and integration. Finally, the dynamics of postdeployment system is also proved marginally stable if the critical initial conditions are satisfied.

Trapping of slow recoil ions: past results and speculations on the future

International Nuclear Information System (INIS)

Prior, M.H.

1983-01-01

A simple electrostatic ion trap has been utilized to capture low energy recoil ions made by fast heavy ion impact upon a neon gas target. The heavy ion beams have been provided by the LBL SuperHILAC and the work has so far concentrated upon studies of the decay of the trapped ion population in time following creation by the pulsed HILAC beam (3.3 msec pulse length, 36Hz repetition rate). The various charge states decay predominantly via electron capture collisions with the ambient gas in the ion trap. By varying the gas composition and density, one can determine the electron capture rate constants from which an effective (velocity averaged) capture cross-section can be obtained. The uniqueness of this work lies in the high charge states, up to Ne 10 + (fully stripped), and the low mean collision energies available (in the range 1.0 to 70.0 eV)

Electron capture rate of a composite of partially ionized atomic nuclei

International Nuclear Information System (INIS)

Yokoi, K.; Takahashi, K.

1979-01-01

Electron captures (or more generally β-transitions) are known to play key roles at various stages of stellar evolution and in many nucleosynthesis processes. With decreasing temperatures and densities, the bound electron captures start to compete with the free electron captures, and eventually in the low-temperature, low-density limit the total capture rate shall converge to that of the orbital electrons observed in laboratory. The authors calculate the occupation probabilities of the electron orbits and the electron capture rates in a mixture of atoms and ions which are supposedly under a chemical equilibrium. (orig./AH)

An experiment on the dynamics of ion implantation and sputtering of surfaces

Energy Technology Data Exchange (ETDEWEB)

Wright, G. M.; Barnard, H. A.; Kesler, L. A.; Peterson, E. E.; Stahle, P. W.; Sullivan, R. M.; Whyte, D. G.; Woller, K. B. [Plasma Science and Fusion Center, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States)

2014-02-15

A major impediment towards a better understanding of the complex plasma-surface interaction is the limited diagnostic access to the material surface while it is undergoing plasma exposure. The Dynamics of ION Implantation and Sputtering Of Surfaces (DIONISOS) experiment overcomes this limitation by uniquely combining powerful, non-perturbing ion beam analysis techniques with a steady-state helicon plasma exposure chamber, allowing for real-time, depth-resolved in situ measurements of material compositions during plasma exposure. Design solutions are described that provide compatibility between the ion beam analysis requirements in the presence of a high-intensity helicon plasma. The three primary ion beam analysis techniques, Rutherford backscattering spectroscopy, elastic recoil detection, and nuclear reaction analysis, are successfully implemented on targets during plasma exposure in DIONISOS. These techniques measure parameters of interest for plasma-material interactions such as erosion/deposition rates of materials and the concentration of plasma fuel species in the material surface.

An experiment on the dynamics of ion implantation and sputtering of surfaces

International Nuclear Information System (INIS)

Wright, G. M.; Barnard, H. A.; Kesler, L. A.; Peterson, E. E.; Stahle, P. W.; Sullivan, R. M.; Whyte, D. G.; Woller, K. B.

2014-01-01

A major impediment towards a better understanding of the complex plasma-surface interaction is the limited diagnostic access to the material surface while it is undergoing plasma exposure. The Dynamics of ION Implantation and Sputtering Of Surfaces (DIONISOS) experiment overcomes this limitation by uniquely combining powerful, non-perturbing ion beam analysis techniques with a steady-state helicon plasma exposure chamber, allowing for real-time, depth-resolved in situ measurements of material compositions during plasma exposure. Design solutions are described that provide compatibility between the ion beam analysis requirements in the presence of a high-intensity helicon plasma. The three primary ion beam analysis techniques, Rutherford backscattering spectroscopy, elastic recoil detection, and nuclear reaction analysis, are successfully implemented on targets during plasma exposure in DIONISOS. These techniques measure parameters of interest for plasma-material interactions such as erosion/deposition rates of materials and the concentration of plasma fuel species in the material surface

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

International Nuclear Information System (INIS)

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

1987-01-01

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

12C+16O sub-barrier radiative capture cross-section measurements

International Nuclear Information System (INIS)

Goasduff, A.; Courtin, S.; Haas, F.; Beck, C.; Lebhertz, D.; Jenkins, D.G.; Fallis, J.; Ruiz, C.; Hutcheon, D.A.; Amandruz, P.A.; Davis, C.; Hager, U.; Ottewell, D.; Ruprecht, G.

2011-01-01

We have performed a heavy ion radiative capture reaction between two light heavy ions, 12 C and 16 O, leading to 28 Si. The present experiment has been performed below Coulomb barrier energies in order to reduce the phase space and to try to shed light on structural effects. Obtained γ-spectra display a previously unobserved strong feeding of intermediate states around 11 MeV at these energies. This new decay branch is not fully reproduced by statistical nor semi-statistical decay scenarios and may imply structural effects. Radiative capture cross-sections are extracted from the data. (authors)

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

International Nuclear Information System (INIS)

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

1984-01-01

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

Dynamic Modeling and Control Studies of a Two-Stage Bubbling Fluidized Bed Adsorber-Reactor for Solid-Sorbent CO{sub 2} Capture

Energy Technology Data Exchange (ETDEWEB)

Modekurti, Srinivasarao; Bhattacharyya, Debangsu; Zitney, Stephen E.

2013-07-31

A one-dimensional, non-isothermal, pressure-driven dynamic model has been developed for a two-stage bubbling fluidized bed (BFB) adsorber-reactor for solid-sorbent carbon dioxide (CO{sub 2}) capture using Aspen Custom Modeler® (ACM). The BFB model for the flow of gas through a continuous phase of downward moving solids considers three regions: emulsion, bubble, and cloud-wake. Both the upper and lower reactor stages are of overflow-type configuration, i.e., the solids leave from the top of each stage. In addition, dynamic models have been developed for the downcomer that transfers solids between the stages and the exit hopper that removes solids from the bottom of the bed. The models of all auxiliary equipment such as valves and gas distributor have been integrated with the main model of the two-stage adsorber reactor. Using the developed dynamic model, the transient responses of various process variables such as CO{sub 2} capture rate and flue gas outlet temperatures have been studied by simulating typical disturbances such as change in the temperature, flowrate, and composition of the incoming flue gas from pulverized coal-fired power plants. In control studies, the performance of a proportional-integral-derivative (PID) controller, feedback-augmented feedforward controller, and linear model predictive controller (LMPC) are evaluated for maintaining the overall CO{sub 2} capture rate at a desired level in the face of typical disturbances.

Beam dynamics studies of the Heavy Ion Fusion Accelerator injector

International Nuclear Information System (INIS)

Henestroza, E.; Yu, S.S.; Eylon, S.

1995-04-01

A driver-scale injector for the Heavy Ion Fusion Accelerator project has been built at LBL. This machine has exceeded the design goals of high voltage (> 2 MV), high current (> 0.8 A of K + ) and low normalized emittance (< 1 π mm-mr). The injector consists of a 750 keV diode pre-injector followed by an electrostatic quadrupole accelerator (ESQ) which provides strong (alternating gradient) focusing for the space-charge dominated beam and simultaneously accelerates the ions to 2 MeV. The fully 3-D PIC code WARP together with EGUN and POISSON were used to design the machine and analyze measurements of voltage, current and phase space distributions. A comparison between beam dynamics characteristics as measured for the injector and corresponding computer calculations will be presented

Application of the GEM Inventory Data Capture Tools for Dynamic Vulnerability Assessment and Recovery Modelling

Science.gov (United States)

Verrucci, Enrica; Bevington, John; Vicini, Alessandro

2014-05-01

A set of open-source tools to create building exposure datasets for seismic risk assessment was developed from 2010-13 by the Inventory Data Capture Tools (IDCT) Risk Global Component of the Global Earthquake Model (GEM). The tools were designed to integrate data derived from remotely-sensed imagery, statistically-sampled in-situ field data of buildings to generate per-building and regional exposure data. A number of software tools were created to aid the development of these data, including mobile data capture tools for in-field structural assessment, and the Spatial Inventory Data Developer (SIDD) for creating "mapping schemes" - statistically-inferred distributions of building stock applied to areas of homogeneous urban land use. These tools were made publically available in January 2014. Exemplar implementations in Europe and Central Asia during the IDCT project highlighted several potential application areas beyond the original scope of the project. These are investigated here. We describe and demonstrate how the GEM-IDCT suite can be used extensively within the framework proposed by the EC-FP7 project SENSUM (Framework to integrate Space-based and in-situ sENSing for dynamic vUlnerability and recovery Monitoring). Specifically, applications in the areas of 1) dynamic vulnerability assessment (pre-event), and 2) recovery monitoring and evaluation (post-event) are discussed. Strategies for using the IDC Tools for these purposes are discussed. The results demonstrate the benefits of using advanced technology tools for data capture, especially in a systematic fashion using the taxonomic standards set by GEM. Originally designed for seismic risk assessment, it is clear the IDCT tools have relevance for multi-hazard risk assessment. When combined with a suitable sampling framework and applied to multi-temporal recovery monitoring, data generated from the tools can reveal spatio-temporal patterns in the quality of recovery activities and resilience trends can be

The Effects of Space-Charge on the Dynamics of the Ion Booster in the Jefferson Lab EIC (JLEIC)

Energy Technology Data Exchange (ETDEWEB)

Bogacz, Alex [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Nissen, Edward [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2017-05-01

Optimization of the booster synchrotron design to operate in the extreme space-charge dominated regime is proposed. This study is motivated by the ultra-high luminosity promised by the JLEIC accelerator complex, which poses several beam dynamics and lattice design challenges for its individual components. We examine the effects of space charge on the dynamics of the booster synchrotron for the proposed JLEIC electron ion collider. This booster will inject and accumulate protons and heavy ions at an energy of 280 MeV and then engage in a process of acceleration and electron cooling to bring it to its extraction energy of 8 GeV. This would then be sent into the ion collider ring part of JLEIC. In order to examine the effects of space charge on the dynamics of this process we use the software SYNERGIA.

Multi-scale modeling of carbon capture systems

Energy Technology Data Exchange (ETDEWEB)

Kress, Joel David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-03-03

The development and scale up of cost effective carbon capture processes is of paramount importance to enable the widespread deployment of these technologies to significantly reduce greenhouse gas emissions. The U.S. Department of Energy initiated the Carbon Capture Simulation Initiative (CCSI) in 2011 with the goal of developing a computational toolset that would enable industry to more effectively identify, design, scale up, operate, and optimize promising concepts. The first half of the presentation will introduce the CCSI Toolset consisting of basic data submodels, steady-state and dynamic process models, process optimization and uncertainty quantification tools, an advanced dynamic process control framework, and high-resolution filtered computationalfluid- dynamics (CFD) submodels. The second half of the presentation will describe a high-fidelity model of a mesoporous silica supported, polyethylenimine (PEI)-impregnated solid sorbent for CO₂ capture. The sorbent model includes a detailed treatment of transport and amine-CO₂- H₂O interactions based on quantum chemistry calculations. Using a Bayesian approach for uncertainty quantification, we calibrate the sorbent model to Thermogravimetric (TGA) data.

The influence of polarizability and charge transfer on specific ion effects in the dynamics of aqueous salt solutions

Science.gov (United States)

Nguyen, Mary; Rick, Steven W.

2018-06-01

The diffusion rates for water molecules in salt solutions depend on the identity of the ions, as well as their concentration. Among the alkali metal ions, cesium and potassium increase and sodium strongly decreases the diffusion constant of water. The origin of the difference can be understood by examining the simulation results using different potential models. In this work, aqueous solutions of salts are simulated with a variety of models. Commonly used non-polarizable models, which otherwise reproduce many experimental properties, do not capture the trend in the diffusion constant, while models which include polarization and/or charge transfer interactions do. For the non-polarizable models, the diffusion constant decreases too strongly with salt concentration. The changes in the water diffusion constant with increasing salt concentration match the diffusion constant of the ion. The ion diffusion constant is dependent on the residence time for water in the ion solvation shell. The non-polarizable models over-estimate the residence time, relative to the translational diffusion constant and so tend to under-estimate the ion and water diffusion constants.

Measurements of fast ion spatial dynamics during magnetic activity in the RFP

Science.gov (United States)

Goetz, J. A.; Anderson, J. K.; Bonofiglo, P.; Kim, J.; McConnell, R.; Magee, R. M.

2017-10-01

Fast ions in the RFP are only weakly affected by a stochastic magnetic field and behave nearly classically in concentration too low to excite Alfvenic activity. At high fast ion concentration sourced by H-NBI in 300kA RFP discharges, a substantial drop in core-localized high pitch fast ions is observed during bursts of coupled EPM and IAE (magnetic island-induced Alfven eigenmode) activity (100-200kHz) through neutral particle analysis. Sourcing instead fast deuterium with NBI, the DD fusion products can measure the dynamics of the fast ion density profile. Both a collimated neutron detector and a new 3MeV fusion proton detector loaned by TriAlpha Energy measure the fast ion density profile with 5cm spatial resolution and 100 μs temporal resolution. In D-NBI, the bursting EPM is excited at slightly lower frequency and the IAE activity is nearly absent, likely due to an isotope effect and loss of wave-particle interaction. In these cases, neutral particle analysis shows little change in the core-localized high pitch fast ion content, and the fusion product profile indicates little change in the fast ion density profile, leaving unexplained the mechanism removing EPM drive. We measure a substantial redistribution of the fast ion profile due to strong lower-frequency ( 30kHz) MHD activity that accompanies the current profile relaxation in the RFP. Profile flattening is strongest in low bulk density discharges, which often occur with a total increase in global neutron flux from acceleration of the beam ions. Work supported by US DoE.

BEAM DYNAMICS STUDIES FOR A COMPACT CARBON ION LINAC FOR THERAPY

Energy Technology Data Exchange (ETDEWEB)

Plastun, A.; Mustapha, B.; Nassiri, A.; Ostroumov, P.

2016-05-01

Feasibility of an Advanced Compact Carbon Ion Linac (ACCIL) for hadron therapy is being studied at Argonne National Laboratory in collaboration with RadiaBeam Technologies. The 45-meter long linac is designed to deliver 109 carbon ions per second with variable energy from 45 MeV/u to 450 MeV/u. S-band structure provides the acceleration in this range. The carbon beam energy can be adjusted from pulse to pulse, making 3D tumor scanning straightforward and fast. Front end accelerating structures such as RFQ, DTL and coupled DTL are designed to operate at lower frequencies. The design of the linac was accompanied with extensive end-to-end beam dynamics studies which are presented in this paper.

Dynamics of the single and double ionization of helium in fast proton collisions

International Nuclear Information System (INIS)

Doerner, R.; Schmidt-Boecking, H.

1991-08-01

A new experimental approach, designed to measure differential ionisation and electron capture cross sections for relativistic heavy ion beams, has been developed and was used to investigate dynamic mechanisms of Helium single and double ionisation in collisions with fast protons. Detailed insight into the dynamics of the ionisation process has been obtained. The experimental results prove, that the many-body momentum exchange between all particles involved, the projectile and target nucleus as well as the emitted electrons, has to be incorporated in order to correctly describe the ionisation collision dynamics. For the proton on Helium collision system the transverse momenta of projectile and recoil-ion were found to be of comparable magnitude only for very close collisions and large scattering angles above 1 mrad, which contribute less than 3% to the total ionisation cross section. (orig./HSI) [de

Nuclear quantum many-body dynamics: from collective vibrations to heavy-ion collisions

International Nuclear Information System (INIS)

Simenel, Cedric

2012-01-01

This report gives a summary of my research on nuclear dynamics during the past ten years. The choice of this field has been motivated by the desire to understand the physics of complex systems obeying quantum mechanics. In particular, the interplay between collective motion and single-particle degrees of freedom is a source of complex and fascinating behaviours. For instance, giant resonances are characterised by a collective vibration of many nucleons, but their decay may occur by the emission of a single nucleon. Another example could be taken from the collision of nuclei where the transfer of few nucleons may have a strong impact on the formation of a compound system is non trivial. To describe these complex systems, one needs to solve the quantum many-body problem. The description of the dynamics of composite systems can be very challenging, especially when two such systems interact. An important goal of nuclear physics is to find a unified way to describe the dynamics of nuclear systems. Ultimately, the same theoretical model should be able to describe vibrations, rotations, fission, all the possible outcomes of heavy-ion collisions (elastic and inelastic scattering, particle transfer, fusion, and multifragmentation), and even the dynamics of neutron star crust. This desire for a global approach to nuclear dynamics has strongly influenced my research activities. In particular, all the numerical applications presented in this report have been obtained from few numerical codes solving equations derived from the same variational principle. Beside the quest for a unified model of nuclear dynamics, possible applications of heavy-ion collisions such as the formation of new nuclei is also a strong motivation for the experimental and theoretical studies of reaction mechanisms. This report is not a review article, but should be considered as a reading guide of the main papers my collaborators and myself have published. It also gives the opportunity to detail some

Dynamic plasma screening effects on semiclassical inelastic electron endash ion collisions in dense plasmas

International Nuclear Information System (INIS)

Jung, Y.

1997-01-01

In dense plasmas, dynamic plasma screening effects are investigated on 1s→2p dipole transition probabilities for electron-impact excitation of hydrogenic ions. The electron endash ion interaction potential is considered by introduction of the plasma dielectric function. A semiclassical straight-line trajectory method is applied to the path of the projectile electron in order to visualize the semiclassical transition probability as a function of the impact parameter, projectile energy, and plasma parameters. The transition probability including the dynamic plasma screening effect is always greater than that including the static plasma screening effect. When the projectile velocity is smaller than the electron thermal velocity, the dynamic polarization screening effect becomes the static plasma screening effect. When the projectile velocity is greater than the electron thermal velocity, then the interaction potential is almost unshielded. The difference between the dynamic and static plasma screening effects is more significant for low-energy projectiles. It is also found that the static plasma screening formula obtained by the Debye endash Hueckel model overestimates the plasma screening effects on the atomic excitation processes in dense plasmas. copyright 1997 American Institute of Physics

Neutrino Signals in Electron-Capture Storage-Ring Experiments

Directory of Open Access Journals (Sweden)

Avraham Gal

2016-06-01

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

Charge changing collision cross sections of atomic ions

International Nuclear Information System (INIS)

Bliman, S.; Dousson, S.; Geller, R.; Jacquot, B.; Van Houtte, D.

1980-05-01

A device has been built to measure charge changing cross sections of atomic ions. It consists of an E.C.R. ion source (Micromafios) that delivers oxygen ions up to charge + 8, argon ions up to charge + 13. The ion source potential may be varied from 1 up to 10 kVolts. A first magnet is used to charge analyze the extracted beam. For a given charge state, the ion beam is passed in a collision cell whose pressure may be varied. The ions undergoing collisions on the target are analyzed by a second magnet and collected. The single collision condition is checked. Different collisions are considered: 1- Charge exchange collisions of argon ions with charge 2<=Z<=12 on argon. Cross sections for capture of 1, 2 and 3 electrons are given. 2- Stripping of argon ions (1<=Z<=4) on argon atoms. 3- Charge exchange of oxygen ions (2<=Z<=8) colliding on deuterium. One and two electron capture cross sections are presented

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

Science.gov (United States)

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

2017-08-23

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

Ion-induced ionization and capture cross sections for DNA nucleobases impacted by light ions

International Nuclear Information System (INIS)

Champion, Christophe; Hanssen, Jocelyn; Galassi, Mariel E; Fojón, Omar; Rivarola, Roberto D; Weck, Philippe F

2012-01-01

Two quantum mechanical models (CB1 and CDW-EIS) are here presented for describing electron ionization and electron capture induced by heavy charged particles in DNA bases. Multiple differential and total cross sections are determined and compared with the scarce existing experimental data.

Orientational order and dynamics of water in bulk and in aqueous solutions of uranyl ions

International Nuclear Information System (INIS)

Chopra, Manish; Choudhury, Niharendu

2014-01-01

Molecular dynamics simulations in canonical ensemble of aqueous solutions of uranyl nitrate and bulk water at ambient condition have been carried out to investigate orientational order and dynamics of water. The orientational distributions of water around a central water molecule in bulk water and around a uranyl ion in an aqueous uranyl solution have been calculated. Orientational dynamics of water in bulk and in aqueous uranyl nitrate solution have also been analysed. (author)

Temperature dynamics and velocity scaling laws for interchange driven, warm ion plasma filaments

DEFF Research Database (Denmark)

Olsen, Jeppe Miki Busk; Madsen, Jens; Nielsen, Anders Henry

2016-01-01

The influence of electron and ion temperature dynamics on the radial convection of isolated structures in magnetically confined plasmas is investigated by means of numerical simulations. It is demonstrated that the maximum radial velocity of these plasma blobs roughly follows the inertial velocity...

Dynamical and statistical aspects of intermediate energy heavy ion collisions

International Nuclear Information System (INIS)

Knoll, J.

1987-01-01

The lectures presented deal with three different topics relevant for the discussion of nuclear collisions at medium to high energies. The first lecture concerns a subject of general interest, the description of statistical systems and their dynamics by the concept of missing information. If presents an excellent scope to formulate statistical theories in such a way that they carefully keep track of the known (relevant) information while maximizing the ignorance about the irrelevant, unknown information. The last two lectures deal with quite actual questions of intermediate energy heavy-ion collisions. These are the multi-fragmentation dynamics of highly excited nuclear systems, and the so called subthreshold particle production. All three subjects are self-contained, and can be read without the knowledge about the other ones. (orig.)

Membrane Anchoring and Ion-Entry Dynamics in P-type ATPase Copper Transport

DEFF Research Database (Denmark)

Grønberg, Christina; Sitsel, Oleg; Lindahl, Erik

2016-01-01

Cu(+)-specific P-type ATPase membrane protein transporters regulate cellular copper levels. The lack of crystal structures in Cu(+)-binding states has limited our understanding of how ion entry and binding are achieved. Here, we characterize the molecular basis of Cu(+) entry using molecular-dynamics...... simulations, structural modeling, and in vitro and in vivo functional assays. Protein structural rearrangements resulting in the exposure of positive charges to bulk solvent rather than to lipid phosphates indicate a direct molecular role of the putative docking platform in Cu(+) delivery. Mutational analyses...... and simulations in the presence and absence of Cu(+) predict that the ion-entry path involves two ion-binding sites: one transient Met148-Cys382 site and one intramembranous site formed by trigonal coordination to Cys384, Asn689, and Met717. The results reconcile earlier biochemical and x-ray absorption data...

Phase transition dynamics in ultra-relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Csernai, L.P.; Kapusta, J.I.; Kluge, G.Y.; Zabrodin, E.E.

1992-11-01

The authors investigate various problems related to the dynamics of a first-order phase transition from quark-gluon plasma to hadronic matter in ultra-relativistic heavy ion collisions. These include nucleation, growth and fusion of hadronic bubbles in either the Bjorken longitudinal hydrodynamic expansion model or the Cooper-Frye-Schonberg spherical hydrodynamic expansion model. With reasonable input parameters the conversion of one phase into the other is relatively close to the idealized adiabatic Maxwell construction, although one can choose parameters such that the conversion is strongly out of equilibrium. 10 refs., 7 figs

Outer-shell transitions in collisions between multiply charged ions and atoms

International Nuclear Information System (INIS)

Bloemen, E.W.P.

1980-01-01

The study of collisions between multiply charged ions and atoms (molecules) is of importance in different areas of research. Usually, the most important process is capture of an electron from the target atom into the projectile ion. In most cases the electron goes to an excited state of the projectile ion. These electron capture processes are studied. The author also studied direct excitation of the target atom and of the projectile ion. (Auth.)

On the role of quantum ion dynamics for the anomalous melting of lithium

Science.gov (United States)

Elatresh, Sabri; Bonev, Stanimir

2011-03-01

Lithium has attracted a lot of interest in relation to a number of counterintuitive electronic and structural changes that it exhibits under pressure. One of the most remarkable properties of dense lithium is its anomalous melting. This behavior was first predicted theoretically based on first-principles molecular dynamics (FPMD) simulations, which treated the ions classically. The lowest melting temperature was determined to be about 275~K at 65~GPa. Recent experiments measured a melting temperature about 100~K lower at the same pressure. In this talk, we will present FPMD calculations of solid and liquid lithium free energies up to 100 GPa that take into account ion quantum dynamics. We examine the significance of the quantum effects for the finite-temperature phase boundaries of lithium and, in particular, its melting curve. Work supported by NSERC, Acenet, and LLNL under Contract DE-AC52-07NA27344.

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

International Nuclear Information System (INIS)

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

1999-01-01

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

Fluorescence profiles and cooling dynamics of laser-cooled Mg+ ions in a linear rf ion trap

International Nuclear Information System (INIS)

Zhao Xianzhen; Ryjkov, Vladimir L.; Schuessler, Hans A.

2006-01-01

Fluorescence line profiles and their implications on the cooling dynamics of the Mg + ions stored in a linear rf trap are studied. The line profile is dictated by the temperature of the ion cloud at different laser detunings. The upper bound of the lowest temperature was estimated for different values of the rf trapping potential amplitude and the buffer gas pressure. A general trend of this ultimate temperature to increase with the rf trapping voltage and buffer gas pressure is expected, with an abrupt change at some critical value corresponding to the transition to and from a strongly correlated liquid or crystal state. While on the one hand this expectation was confirmed when the buffer gas pressure was varied; on the other hand the influence of the amplitude of the trapping voltage on the ultimate temperature shows an interesting new feature of first dipping down before the sharp increase occurs

The dynamics of Ca2+ ions within the solvation shell of calbindin D9k.

Directory of Open Access Journals (Sweden)

Elad Project

Full Text Available The encounter of a Ca(2+ ion with a protein and its subsequent binding to specific binding sites is an intricate process that cannot be fully elucidated from experimental observations. We have applied Molecular Dynamics to study this process with atomistic details, using Calbindin D9k (CaB as a model protein. The simulations show that in most of the time the Ca(2+ ion spends within the Debye radius of CaB, it is being detained at the 1st and 2nd solvation shells. While being detained near the protein, the diffusion coefficient of the ion is significantly reduced. However, due to the relatively long period of detainment, the ion can scan an appreciable surface of the protein. The enhanced propagation of the ion on the surface has a functional role: significantly increasing the ability of the ion to scan the protein's surface before being dispersed to the bulk. The contribution of this mechanism to Ca(2+ binding becomes significant at low ion concentrations, where the intervals between successive encounters with the protein are getting longer. The efficiency of the surface diffusion is affected by the distribution of charges on the protein's surface. Comparison of the Ca(2+ binding dynamics in CaB and its E60D mutant reveals that in the wild type (WT protein the carboxylate of E60 function as a preferred landing-site for the Ca(2+ arriving from the bulk, followed by delivering it to the final binding site. Replacement of the glutamate by aspartate significantly reduced the ability to transfer Ca(2+ ions from D60 to the final binding site, explaining the observed decrement in the affinity of the mutated protein to Ca(2+.

RNA Structural Dynamics As Captured by Molecular Simulations: A Comprehensive Overview

Science.gov (United States)

2018-01-01

With both catalytic and genetic functions, ribonucleic acid (RNA) is perhaps the most pluripotent chemical species in molecular biology, and its functions are intimately linked to its structure and dynamics. Computer simulations, and in particular atomistic molecular dynamics (MD), allow structural dynamics of biomolecular systems to be investigated with unprecedented temporal and spatial resolution. We here provide a comprehensive overview of the fast-developing field of MD simulations of RNA molecules. We begin with an in-depth, evaluatory coverage of the most fundamental methodological challenges that set the basis for the future development of the field, in particular, the current developments and inherent physical limitations of the atomistic force fields and the recent advances in a broad spectrum of enhanced sampling methods. We also survey the closely related field of coarse-grained modeling of RNA systems. After dealing with the methodological aspects, we provide an exhaustive overview of the available RNA simulation literature, ranging from studies of the smallest RNA oligonucleotides to investigations of the entire ribosome. Our review encompasses tetranucleotides, tetraloops, a number of small RNA motifs, A-helix RNA, kissing-loop complexes, the TAR RNA element, the decoding center and other important regions of the ribosome, as well as assorted others systems. Extended sections are devoted to RNA–ion interactions, ribozymes, riboswitches, and protein/RNA complexes. Our overview is written for as broad of an audience as possible, aiming to provide a much-needed interdisciplinary bridge between computation and experiment, together with a perspective on the future of the field. PMID:29297679

Chaotic Dynamics Mediates Brain State Transitions, Driven by Changes in Extracellular Ion Concentrations

DEFF Research Database (Denmark)

Rasmussen, Rune; H. Jensen, Mogens; L. Heltberg, Mathias

2017-01-01

Previous studies have suggested that changes in extracellular ion concentrations initiate the transition from an activity state that characterizes sleep in cortical neurons to states that characterize wakeful- ness. However, because neuronal activity and extra- cellular ion concentrations...... are interdependent, isolating their unique roles during sleep-wake transitions is not possible in vivo. Here, we extend the Averaged-Neuron model and demonstrate that, although changes in extracellular ion concentrations occur concurrently, decreasing the conductance of calcium-dependent potassium channels initiates...... the transition from sleep to wakefulness. We find that sleep is governed by stable, self-sustained oscillations in neuronal firing patterns, whereas the quiet awake state and active awake state are both governed by irregular oscillations and chaotic dynamics; transitions between these separable awake states...

Photodissociation dynamics of Ar2(+) and Ar3(+) excited by 527 nm photons.

Science.gov (United States)

Lepère, V; Picard, Y J; Barat, M; Fayeton, J A; Lucas, B; Béroff, K

2009-05-21

The photofragmentation dynamics of Ar(2)(+) and Ar(3)(+) clusters has been investigated at a 527 nm wavelength (2.35 eV) using a setup that allows simultaneous detection of the ionic and neutral fragments in a coincidence experiment. Measurement of positions and times of flight enables in principle a complete description of the fragmentation dynamics. The photofragmentation dynamics of Ar(3)(+) clusters is similar to that of Ar(2)(+) with, in addition, the ejection of a third fragment that can be neutral or ionized via a resonant electron capture. This is attributed to the triangular geometry of the Ar(3)(+) ion.

Molecular dynamics simulation study of the "stay or leave" problem for two magnesium ions in gene transcription.

Science.gov (United States)

Wu, Shaogui

2017-06-01

Two magnesium ions play important roles in nucleotide addition cycle (NAC) of gene transcription. However, at the end of each NAC, why does one ion stay in the active site while the other ion leaves with product pyrophosphate (PP i )? This problem still remains obscure. In this work, we studied the problem using all-atom molecular dynamics simulation combined with steered molecular dynamics and umbrella sampling simulation methods. Our simulations reveal that although both ions are located in the active site after chemistry, their detailed positions are not symmetrical, leading to their different forces from surrounding groups. One ion makes weaker contacts with PP i than the whole protein. Hence, PP i release is less likely to take it away. The other one forms tighter contacts with PP i relative to the protein. The formed (Mg 2+ -PP i ) 2- complex is found to break the contacts with surrounding protein residues one by one so as to dissociate from the active site. This effectively avoids the coexistence of two ions in the active site after PP i release and guarantees a reasonable Mg 2+ ion number in the active site for the next NAC. The observations from this work can provide valuable information for comprehensively understanding the molecular mechanism of transcription. Proteins 2017; 85:1002-1007. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Dynamics of RF captured cooled proton beams

International Nuclear Information System (INIS)

Kells, W.; Mills, F.

1983-01-01

In the course of electron cooling experiments at the Electron Cooling Ring (ECR) at Fermilab, several peculiar features of the longitudinal phase space of cold protons (200 MeV) captured in RF buckets were observed. Here we present the experimental facts, present a simple theory, and summarize computer simulation results which support the theory and facts

ELECTRON-CAPTURE IN HIGHLY-CHARGED ION-ATOM COLLISIONS

NARCIS (Netherlands)

MORGENSTERN, R

1993-01-01

An attempt is made to identify the most important mechanisms responsible for the rearrangement of electrons during collisions between multiply charged ions and atoms at keV energies. It is discussed to which extent the influence of binding energy, angular momentum of heavy particles and electrons,

Dynamics of a single ion in a perturbed Penning trap: Octupolar perturbation

International Nuclear Information System (INIS)

Lara, Martin; Salas, J. Pablo

2004-01-01

Imperfections in the design or implementation of Penning traps may give rise to electrostatic perturbations that introduce nonlinearities in the dynamics. In this paper we investigate, from the point of view of classical mechanics, the dynamics of a single ion trapped in a Penning trap perturbed by an octupolar perturbation. Because of the axial symmetry of the problem, the system has two degrees of freedom. Hence, this model is ideal to be managed by numerical techniques like continuation of families of periodic orbits and Poincare surfaces of section. We find that, through the variation of the two parameters controlling the dynamics, several periodic orbits emanate from two fundamental periodic orbits. This process produces important changes (bifurcations) in the phase space structure leading to chaotic behavior

Femtosecond study of the effects of ions and hydrophobes on the dynamics of water.

Science.gov (United States)

van der Post, Sietse T; Tielrooij, Klaas-Jan; Hunger, Johannes; Backus, Ellen H G; Bakker, Huib J

2013-01-01

We study the effects of ions and hydrophobic molecular groups on the orientational dynamics of water using THz dielectric relaxation (THz-DR) and polarization-resolved femtosecond infrared (fs-IR) pump-probe spectroscopy. We measure the dynamics of water in solutions of NaI, NaCl, CsCl, guanidinium chloride (GndCl) and tetramethyl guanidinium chloride (TMGndCl) of different the static dipoles of their surrounding water molecules. With fs-IR we find that concentrations. With THz-DR we observe that strongly hydrated cations align the OD groups that form hydrogen bonds to halide anions reorient with two distinct time constants of 2 +/- 0.3 ps and 9 +/- 1 ps. The fast process is assigned to a wobbling motion of the OD group that keeps the hydrogen bond with the anion intact. The amplitude of this wobbling motion depends on the nature of both the anion and the counter cation. The replacement of four of the six hydrogen atoms of the weakly hydrated cation guanidinium by hydrophobic methyl groups leads to an exceptionally strong slowing down of the water dynamics. Hydrophobic groups thus appear to have a much stronger effect on the dynamics of water than ions. These findings give new insights in the mechanism of protein denaturation by GndCl and TMGndCl.

Quantum molecular dynamics study on energy transfer to the secondary electron in surface collision process of an ion

International Nuclear Information System (INIS)

Shibahara, M; Satake, S; Taniguchi, J

2008-01-01

In the present study the quantum molecular dynamics method was applied to an energy transfer problem to an electron during ionic surface collision process in order to elucidate how energy of ionic collision transfers to the emitted electrons. Effects of various physical parameters, such as the collision velocity and interaction strength between the observed electron and the classical particles on the energy transfer to the electron were investigated by the quantum molecular dynamics method when the potassium ion was collided with the surface so as to elucidate the energy path to the electron and the predominant factor of energy transfer to the electron. Effects of potential energy between the ion and the electron and that between the surface molecule and the electron on the electronic energy transfer were shown in the present paper. The energy transfer to the observed secondary electron through the potential energy term between the ion and the electron was much dependent on the ion collision energy although the energy increase to the observed secondary electron was not monotonous through the potential energy between the ion and surface molecules with the change of the ion collision energy

Low energy ion beam dynamics of NANOGAN ECR ion source

Energy Technology Data Exchange (ETDEWEB)

Kumar, Sarvesh, E-mail: sarvesh@iuac.res.in; Mandal, A.

2016-04-01

A new low energy ion beam facility (LEIBF) has been developed for providing the mass analyzed highly charged intense ion beams of energy ranging from a few tens of keV to a few MeV for atomic, molecular and materials sciences research. The new facility consists of an all permanent magnet 10 GHz electron cyclotron resonance (ECR) ion source (NANOGAN) installed on a high voltage platform (400 kV) which provides large currents of multiply charged ion beams. Higher emittance at low energy of intense ion beam puts a tremendous challenge to the beam optical design of this facility. The beam line consists of mainly the electrostatic quadrupoles, an accelerating section, analyzing cum switching magnet and suitable beam diagnostics including vacuum components. The accelerated ion beam is analyzed for a particular mass to charge (m/q) ratio as well as guided to three different lines along 75°, 90° and 105° using a large acceptance analyzing cum switching magnet. The details of transverse beam optics to all the beam lines with TRANSPORT and GICOSY beam optics codes are being described. Field computation code, OPERA 3D has been utilized to design the magnets and electrostatic quadrupoles. A theoretical estimation of emittance for optimized geometry of ion source is given so as to form the basis of beam optics calculations. The method of quadrupole scan of the beam is used to characterize the emittance of the final beam on the target. The measured beam emittance increases with m/q ratios of various ion beams similar to the trend observed theoretically.

Capture into resonance and phase space dynamics in optical centrifuge

Science.gov (United States)

Armon, Tsafrir; Friedland, Lazar

2016-05-01

The process of capture of a molecular enesemble into rotational resonance in the optical centrifuge is investigated. The adiabaticity and phase space incompressibility are used to find the resonant capture probability in terms of two dimensionless parameters P1 , 2 characterising the driving strength and the nonlinearity, and related to three characteristic time scales in the problem. The analysis is based on the transformation to action-angle variables and the single resonance approximation, yielding reduction of the three-dimensional rotation problem to one degree of freedom. The analytic results for capture probability are in a good agreement with simulations. The existing experiments satisfy the validity conditions of the theory. This work was supported by the Israel Science Foundation Grant 30/14.

Nascent chromatin capture proteomics determines chromatin dynamics during DNA replication and identifies unknown fork components

DEFF Research Database (Denmark)

Alabert, Constance; Bukowski-Wills, Jimi-Carlo; Lee, Sung-Po

2014-01-01

To maintain genome function and stability, DNA sequence and its organization into chromatin must be duplicated during cell division. Understanding how entire chromosomes are copied remains a major challenge. Here, we use nascent chromatin capture (NCC) to profile chromatin proteome dynamics during...... replication in human cells. NCC relies on biotin-dUTP labelling of replicating DNA, affinity purification and quantitative proteomics. Comparing nascent chromatin with mature post-replicative chromatin, we provide association dynamics for 3,995 proteins. The replication machinery and 485 chromatin factors...... such as CAF-1, DNMT1 and SUV39h1 are enriched in nascent chromatin, whereas 170 factors including histone H1, DNMT3, MBD1-3 and PRC1 show delayed association. This correlates with H4K5K12diAc removal and H3K9me1 accumulation, whereas H3K27me3 and H3K9me3 remain unchanged. Finally, we combine NCC enrichment...

DYNAMICS OF TIDALLY CAPTURED PLANETS IN THE GALACTIC CENTER

International Nuclear Information System (INIS)

Trani, Alessandro A.; Bressan, Alessandro; Mapelli, Michela; Spera, Mario

2016-01-01

Recent observations suggest ongoing planet formation in the innermost parsec of the Galactic center. The supermassive black hole (SMBH) might strip planets or planetary embryos from their parent star, bringing them close enough to be tidally disrupted. Photoevaporation by the ultraviolet field of young stars, combined with ongoing tidal disruption, could enhance the near-infrared luminosity of such starless planets, making their detection possible even with current facilities. In this paper, we investigate the chance of planet tidal captures by means of high-accuracy N -body simulations exploiting Mikkola's algorithmic regularization. We consider both planets lying in the clockwise (CW) disk and planets initially bound to the S-stars. We show that tidally captured planets remain on orbits close to those of their parent star. Moreover, the semimajor axis of the planetary orbit can be predicted by simple analytic assumptions in the case of prograde orbits. We find that starless planets that were initially bound to CW disk stars have mild eccentricities and tend to remain in the CW disk. However, we speculate that angular momentum diffusion and scattering by other young stars in the CW disk might bring starless planets into orbits with low angular momentum. In contrast, planets initially bound to S-stars are captured by the SMBH on highly eccentric orbits, matching the orbital properties of the clouds G1 and G2. Our predictions apply not only to planets but also to low-mass stars initially bound to the S-stars and tidally captured by the SMBH.

The ion-acoustic soliton: A gas-dynamic viewpoint

Science.gov (United States)

McKenzie, J. F.

2002-03-01

The properties of fully nonlinear ion-acoustic solitons are investigated by interpreting conservation of total momentum as the structure equation for the proton flow in the wave. In most studies momentum conservation is regarded as the first integral of the Poisson equation for the electric potential and is interpreted as being analogous to a particle moving in a pseudo-potential well. By adopting an essentially gas-dynamic viewpoint, which emphasizes momentum conservation and the properties of the Bernoulli-type energy equations, the crucial role played by the proton sonic point becomes apparent. The relationship (implied by energy conservation) between the electron and proton speeds in the transition yields a locus—the hodograph of the system-which shows that, in the first half of the soliton, the electrons initially lag behind the protons until the charge neutral point is reached, after which they run ahead of the protons. The system reaches an equilibrium point (the center of the soliton) before the proton flow goes sonic. It follows that the critical ion-acoustic Mach number, Mc, above which smooth, continuous solitons cannot be constructed, stems from the requirement that the two equilibrium points of the structure equation coalesce at the proton sonic point of the flow. In general the range of the ion-acoustic Mach numbers, Mep, in which solitons exist, is extended beyond the classical range 1ion-acoustic Mach number, can be between 1.3kTe and 10kTe depending upon the values of the adiabatic indices of the electrons and protons and the proton Mach number.

Utilization of ion source 'SUPERSHYPIE' in the study of low energy ion-atom and ion-molecule collisions

International Nuclear Information System (INIS)

Bazin, V.; Boduch, P.; Chesnel, J.Y.; Fremont, F.; Lecler, D.; Pacquet, J. Y.; Gaubert, G.; Leroy, R.

1999-01-01

Modifications in the ECR 4M ion source are described, which conducted to realization of the advanced source 'SUPERSHYPIE'. The Ar 8+ ion collision with Cs(6s,6p) were studied by photon spectroscopy at low energy, where the process is dominated by simple electron capture. Results obtained with 'SUPERSHYPIE' source are presented. The source was utilized also in ion-molecule collisions (CO, H 2 ) to study the spectra of recoil ions and Auger electron spectra in the Ar 17+ He collisions. The excellent performances of 'SUPERSHYPIE' in high charge production and concerning its accurate and fine control and stability are illustrated and underlined as compared with those of ECR 4M source

Proceedings of the Workshop on open problems in heavy ion reaction dynamics at VIVITRON energies

International Nuclear Information System (INIS)

Beck, F.A.

1993-01-01

Some problems of heavy ion reaction dynamics at the VIVITRON tandem accelerator and the experimental facilities are discussed at the meeting. Topics include light dinuclear systems, collision dynamics at low energies, fission evaporation and fusion of heavy nuclei and others. Most documents consist of transparencies presented at the workshop, texts of papers are missing. All items are indexed and abstracted for the INIS database. (K.A.)

Proceedings of the Workshop on open problems in heavy ion reaction dynamics at VIVITRON energies

Energy Technology Data Exchange (ETDEWEB)

Beck, F. A.

1993-07-01

Some problems of heavy ion reaction dynamics at the VIVITRON tandem accelerator and the experimental facilities are discussed at the meeting. Topics include light dinuclear systems, collision dynamics at low energies, fission evaporation and fusion of heavy nuclei and others. Most documents consist of transparencies presented at the workshop, texts of papers are missing. All items are indexed and abstracted for the INIS database. (K.A.).

Recent investigations on electronic capture in atomic collisions

International Nuclear Information System (INIS)

Rivarola, R.D.

1988-01-01

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

Collective flow as a probe of heavy-ion reaction dynamics

International Nuclear Information System (INIS)

Awes, T.C.

1997-01-01

Collective flow of nuclear matter probes the dynamics of heavy-ion reactions and can provide information about the nuclear-matter equation of state. In particular, the incident energy dependences of collective flow may be a sensitive means to deduce the existence of a Quark Gluon Plasma phase in the equation of state. Collective flow measurements from 30 A MeV to 200 A GeV incident energies are briefly reviewed. Preliminary results on collective flow from the WA98 experiment at the CERN SPS are presented

TARGET EXCITATION IN BARE ION XE/AR COLLISIONS STUDIED BY ELECTRON TARGET ION COINCIDENCES

NARCIS (Netherlands)

DENIJS, G; HOEKSTRA, R; MORGENSTERN, R

We present electron spectra resulting from collisions of bare ions N-15(7+) and C-13(6+) on Ar and the charge state distribution of target ions resulting from C-13(6+)-Xe collisions. From both type of experiments we find evidence that electron capture accompanied by target excitation is an important

The ion-acoustic soliton: A gas-dynamic viewpoint

International Nuclear Information System (INIS)

McKenzie, J.F.

2002-01-01

The properties of fully nonlinear ion-acoustic solitons are investigated by interpreting conservation of total momentum as the structure equation for the proton flow in the wave. In most studies momentum conservation is regarded as the first integral of the Poisson equation for the electric potential and is interpreted as being analogous to a particle moving in a pseudo-potential well. By adopting an essentially gas-dynamic viewpoint, which emphasizes momentum conservation and the properties of the Bernoulli-type energy equations, the crucial role played by the proton sonic point becomes apparent. The relationship (implied by energy conservation) between the electron and proton speeds in the transition yields a locus--the hodograph of the system-which shows that, in the first half of the soliton, the electrons initially lag behind the protons until the charge neutral point is reached, after which they run ahead of the protons. The system reaches an equilibrium point (the center of the soliton) before the proton flow goes sonic. It follows that the critical ion-acoustic Mach number, M c , above which smooth, continuous solitons cannot be constructed, stems from the requirement that the two equilibrium points of the structure equation coalesce at the proton sonic point of the flow. In general the range of the ion-acoustic Mach numbers, M ep , in which solitons exist, is extended beyond the classical range 1 ep 2 shaped pulses characteristic of weakly nonlinear waves and shows that solitons exist only if 1 ep e and 10kT e depending upon the values of the adiabatic indices of the electrons and protons and the proton Mach number

Molecular Dynamics Simulations of Collisional Cooling and Ordering of Multiply Charged Ions in a Penning Trap

International Nuclear Information System (INIS)

Holder, J.P.; Church, D.A.; Gruber, L.; DeWitt, H.E.; Beck, B.R.; Schneider, D.

2000-01-01

Molecular dynamics simulations are used to help design new experiments by modeling the cooling of small numbers of trapped multiply charged ions by Coulomb interactions with laser-cooled Be + ions. A Verlet algorithm is used to integrate the equations of motion of two species of point ions interacting in an ideal Penning trap. We use a time step short enough to follow the cyclotron motion of the ions. Axial and radial temperatures for each species are saved periodically. Direct heating and cooling of each species in the simulation can be performed by periodically rescaling velocities. Of interest are Fe 11+ due to a EUV-optical double resonance for imaging and manipulating the ions, and Ca 14+ since a ground state fine structure transition has a convenient wavelength in the tunable laser range

Na-ion dynamics in Quasi-1D compound NaV2O4

International Nuclear Information System (INIS)

Månsson, M; Umegaki, I; Nozaki, H; Higuchi, Y; Sugiyama, J; Kawasaki, I; Watanabe, I; Sakurai, H

2014-01-01

We have used the pulsed muon source at ISIS to study high-temperature Na-ion dynamics in the quasi-one-dimensional (Q1D) metallic antiferromagnet NaV 2 O 4 . By performing systematic zero-field and longitudinal-field measurements as a function of temperature we clearly distinguish that the hopping rate increases exponentially above T diff ≈ 250 K. The data is well fitted to an Arrhenius type equation typical for a diffusion process, showing that the Na-ions starts to be mobile above T diff . Such results make this compound very interesting for the tuning of Q1D magnetism using atomic-scale ion-texturing through the periodic potential from ordered Na-vacancies. Further, it also opens the door to possible use of NaV 2 O 4 and related compounds in energy related applications

Enhanced electron capture by fast heavy di-clusters exciting solids

International Nuclear Information System (INIS)

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

1985-01-01

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

Revisiting the issue of elite capture in participatory initiatives

DEFF Research Database (Denmark)

Lund, Jens Friis; Saito-Jensen, Moeko

2013-01-01

of resistance orchestrated by initially disadvantaged groups. Based on the cases we argue that studies of elite capture should be based on in-depth and longitudinal empirical investigations that carefully characterize forms and outcomes of elite capture and consider both the changing dynamics of social settings...

Capturing multi-stage fuzzy uncertainties in hybrid system dynamics and agent-based models for enhancing policy implementation in health systems research.

Science.gov (United States)

Liu, Shiyong; Triantis, Konstantinos P; Zhao, Li; Wang, Youfa

2018-01-01

In practical research, it was found that most people made health-related decisions not based on numerical data but on perceptions. Examples include the perceptions and their corresponding linguistic values of health risks such as, smoking, syringe sharing, eating energy-dense food, drinking sugar-sweetened beverages etc. For the sake of understanding the mechanisms that affect the implementations of health-related interventions, we employ fuzzy variables to quantify linguistic variable in healthcare modeling where we employ an integrated system dynamics and agent-based model. In a nonlinear causal-driven simulation environment driven by feedback loops, we mathematically demonstrate how interventions at an aggregate level affect the dynamics of linguistic variables that are captured by fuzzy agents and how interactions among fuzzy agents, at the same time, affect the formation of different clusters(groups) that are targeted by specific interventions. In this paper, we provide an innovative framework to capture multi-stage fuzzy uncertainties manifested among interacting heterogeneous agents (individuals) and intervention decisions that affect homogeneous agents (groups of individuals) in a hybrid model that combines an agent-based simulation model (ABM) and a system dynamics models (SDM). Having built the platform to incorporate high-dimension data in a hybrid ABM/SDM model, this paper demonstrates how one can obtain the state variable behaviors in the SDM and the corresponding values of linguistic variables in the ABM. This research provides a way to incorporate high-dimension data in a hybrid ABM/SDM model. This research not only enriches the application of fuzzy set theory by capturing the dynamics of variables associated with interacting fuzzy agents that lead to aggregate behaviors but also informs implementation research by enabling the incorporation of linguistic variables at both individual and institutional levels, which makes unstructured linguistic data

Dynamics on the positron capture and accelerating sections of CLIC

CERN Document Server

Poirier, Freddy; Vivoli, Alessandro; Dadoun, Olivier; Lepercq, Pierre; Variola, Alessandro

2011-01-01

The CLIC Pre-Injector Linac for the e+ beam is composed of an Adiabatic Matching Device (AMD) followed by 4 (or 5) accelerating RF structures embedded in a solenoidal magnetic field. The accelerating sections are based on 2 GHz long travelling wave structures. In this note, the positrons capture strategy downstream the AMD is reviewed. The first RF structure can be phased either for full acceleration or for deceleration. In the latter case, the simulations results show that the number of e+ capture at the end of the 200 MeV Pre-Injector Linac is increased. Then the impact of the space charge is presented. Additional techniques are also studied to explore the potentiality of increasing the number of e+ namely an extra RF field at the beginning of the capture section and a higher solenoidal field.

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

Energy Technology Data Exchange (ETDEWEB)

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

1999-11-01

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

Collisions of low-energy multicharged ions

International Nuclear Information System (INIS)

Phaneuf, R.A.; Crandall, D.H.

1981-01-01

Experimental measurements of cross sections for collisions of multiply charged ions with atoms at the lowest attainable collision energies are reported. Emphasis is on electron capture from hydrogen atoms by multiply charged ions at energies below 1 keV/amu. The principal effort is the development of a merged-ion-atom-beams apparatus for studies down to 1 eV/amu relative energy

Studies on the dynamics of heavy ion collisions at intermediate energies

International Nuclear Information System (INIS)

David, C.; Hartnack, C; Aichelin, J.

1997-01-01

We use the Quantum Molecular Dynamics model for the investigation of the dynamics of heavy ion collisions at intermediate energies. A detailed comparison between different versions of the models demonstrate the influence of not exactly known parameters in the description of nuclei like interaction range or initial densities and thus describes the limits of predictive power. The dynamics of the reaction are discussed quite similarly in the different models. A radial expansion with a linear velocity profile is found at central collisions. A strong interaction of pions with nuclear matter is reported. This interaction is strongly influenced by the lifetime of baryonic resonances in nuclear matter. These lifetimes depend strongly on the mass distribution of the resonances. These mass distributions are influenced by the momentum distribution in the nuclei. Here the inclusion of the spectral function shows visible effects. These effects influence the energy dissipation in nuclei and thus enter e.g. into the analysis of p + A collisions for the GEDEON project. (author)

Understanding plume splitting of laser ablated plasma: A view from ion distribution dynamics

Energy Technology Data Exchange (ETDEWEB)

Wu, Jian; Li, Xingwen; Wei, Wenfu; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Shaanxi 710049 (China)

2013-11-15

Plume splitting in low-pressure ambient air was understood in view of ion distribution dynamics from the laser ablated Al plasma (1064 nm 0.57 J/mm{sup 2}) by combining fast photography and spatially resolved spectroscopy. In the beginning, the spectral lines were mainly from the Al III ion. Then, the Bragg peak in stopping power of the ambient gas to Al III could be the dominant reason for the enhanced emission from the fast moving part, and the recombination of Al III to Al I-II ions near the target surface was response to the radiations from the slow moving/stationary part. As the ambient gas pressure increased, stopping distances of the Al III decreased, and radiation from the air ions became pronounced. The laser shadowgraph image at 1100 Pa indicated that the shock wave front located between the fast moving and slow moving parts. Electron densities of the fast moving plasma, which peaked at the plasma front, were on the order of 10{sup 16} cm{sup −3}, and the electron temperatures were 2–3 eV.

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

Science.gov (United States)

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

2001-05-01

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

On experimental and theoretical studies of dynamics and particle production in p-nucleus and heavy ion reactions

Energy Technology Data Exchange (ETDEWEB)

Fokin, A.B

1998-11-01

Several experiments and theoretical models of intermediate energy heavy ion collision physics are presented in this thesis. Statistical and dynamical aspects of nuclear collisions are widely discussed these days, particularly in connection with the multifragmentation phenomenon and the possible link to a liquid-gas phase transition in the spinodal region of nuclear matter phase diagram. Experimental techniques which allow us to measure various parameters of hot and dense (equilibrated) regions (emission sources) formed in a heavy ion collision are well established nowadays. In recent CHIC (Celsius Heavy Ion Collaboration) experiments the properties of such sources were measured using slowly ramping mode of the CELSIUS storage ring. In this thesis the entropy and chaos production in nuclear collisions is discussed in connection with the t/d/p ratios. Subthreshold pion production explores collective effects in heavy ion collisions and brings additional information about the equation of state of nuclear matter. Continuous pion production excitation functions were measured in the beam energy region from far below the nucleon-nucleon threshold up to the delta dominant region. Mass and angular dependencies of pion production are discussed. A version of the molecular dynamics model which includes pion production in direct nucleon-nucleon collisions was developed and experimental data were analysed in the scope of this model. Properties of the emission sources formed in heavy ion collisions at energies below 50A MeV were studied in the experiments of fragmentation type performed by CHIC. Temperatures of these sources were extracted from fragment energy spectra and from `isotopic effect`. A version of the quantum molecular dynamics model, where the Pauli potential is introduced into the Hamiltonian, was combined with the statistical multifragmentation model and used to explore dynamical and statistical properties of the reaction development. The artificial neural networks

On experimental and theoretical studies of dynamics and particle production in p-nucleus and heavy ion reactions

International Nuclear Information System (INIS)

Fokin, A.B.

1998-11-01

Several experiments and theoretical models of intermediate energy heavy ion collision physics are presented in this thesis. Statistical and dynamical aspects of nuclear collisions are widely discussed these days, particularly in connection with the multifragmentation phenomenon and the possible link to a liquid-gas phase transition in the spinodal region of nuclear matter phase diagram. Experimental techniques which allow us to measure various parameters of hot and dense (equilibrated) regions (emission sources) formed in a heavy ion collision are well established nowadays. In recent CHIC (Celsius Heavy Ion Collaboration) experiments the properties of such sources were measured using slowly ramping mode of the CELSIUS storage ring. In this thesis the entropy and chaos production in nuclear collisions is discussed in connection with the t/d/p ratios. Subthreshold pion production explores collective effects in heavy ion collisions and brings additional information about the equation of state of nuclear matter. Continuous pion production excitation functions were measured in the beam energy region from far below the nucleon-nucleon threshold up to the delta dominant region. Mass and angular dependencies of pion production are discussed. A version of the molecular dynamics model which includes pion production in direct nucleon-nucleon collisions was developed and experimental data were analysed in the scope of this model. Properties of the emission sources formed in heavy ion collisions at energies below 50A MeV were studied in the experiments of fragmentation type performed by CHIC. Temperatures of these sources were extracted from fragment energy spectra and from 'isotopic effect'. A version of the quantum molecular dynamics model, where the Pauli potential is introduced into the Hamiltonian, was combined with the statistical multifragmentation model and used to explore dynamical and statistical properties of the reaction development. The artificial neural networks

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

CERN Multimedia

2002-01-01

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

Conformational Dynamics on the Extracellular Side of LeuT Controlled by Na+ and K+ Ions and the Protonation State of Glu(290)

DEFF Research Database (Denmark)

Khelashvili, George; Schmidt, Solveig Gaarde; Shi, Lei

2016-01-01

Na+ ions and substrate have left, and the transporter prepares for a new cycle. We compare the results with the consequences of binding Na+ in the same apo system. Analysis of >50-μs atomistic molecular dynamics and enhanced sampling trajectories of constructs with Glu290, either charged or neutral......Ions play key mechanistic roles in the gating dynamics of neurotransmitter:sodium symporters (NSSs). In recent microsecond scale molecular dynamics simulations of a complete model of the dopamine transporter, a NSS protein, we observed a partitioning of K+ ions from the intracellular side toward...... the unoccupied Na2 site of dopamine transporter following the release of the Na2-bound Na+. Here we evaluate with computational simulations and experimental measurements of ion affinities under corresponding conditions, the consequences of K+ binding in the Na2 site of LeuT, a bacterial homolog of NSS, when both...

Kinetic studies of ICF target dynamics with ePLAS

Science.gov (United States)

Mason, R. J.

2016-10-01

The ePLAS code was recently used1 to show that a modeling change from artificial to real viscosity can result in a decrease of the predicted performance of ICF targets. This code typically follows either fluid or PIC electrons with fluid ions in self-consistent E - and B - fields computed by the Implicit Moment Method2. For the present study the ions have instead been run as PIC particles undergoing Krook-like self-collisions. The ePLAS collision model continually redistributes the ion particle properties toward a local Maxwellian, while conserving the mean density, momentum and energy. Whereas the use of real viscosity captures large Knudsen Number effects as the active target dimensions shrink below the ion mean-free-path, the new kinetic modeling can manifest additional effects such as collisional shock precursors3 from the escape and streaming of the fastest particle ions. In 2D cylindrical geometry we will explore how such kinetic shock extensions might affect shell and core compression dynamics in ICF target implosions.

Dynamic energy spectrum and energy deposition in solid target by intense pulsed ion beams

Institute of Scientific and Technical Information of China (English)

Xiao Yu; Xiao-Yun Le; Zheng Liu; Jie Shen; Yu I.Isakova; Hao-Wen Zhong; Jie Zhang; Sha Yan; Gao-Long Zhang; Xiao-Fu Zhang

2017-01-01

A method for analyzing the dynamic energy spectrum of intense pulsed ion beam (IPIB) was proposed.Its influence on beam energy deposition in metal target was studied with IPIB produced by two types of magnetically insulated diodes (MID).The emission of IPIB was described with space charge limitation model,and the dynamic energy spectrum was further analyzed with time-of-flight method.IPIBs generated by pulsed accelerators of BIPPAB-450 (active MID) and TEMP-4M (passive MID) were studied.The dynamic energy spectrum was used to deduce the power density distribution of IPIB in the target with Monte Carlo simulation and infrared imaging diagnostics.The effect on the distribution and evolution of thermal field induced by the characteristics of IPIB dynamic energy spectrum was discussed.

Entirely irrelevant distractors can capture and captivate attention.

Science.gov (United States)

Forster, Sophie; Lavie, Nilli

2011-12-01

The question of whether a stimulus onset may capture attention when it is entirely irrelevant to the task and even in the absence of any attentional settings for abrupt onset or any dynamic changes has been highly controversial. In the present study, we designed a novel irrelevant capture task to address this question. Participants engaged in a continuous task making sequential forced choice (letter or digit) responses to each item in an alphanumeric matrix that remained on screen throughout many responses. This task therefore involved no attentional settings for onset or indeed any dynamic changes, yet the brief onset of an entirely irrelevant distractor (a cartoon picture) resulted in significant slowing of the two (Experiment 1) or three (Experiment 2) responses immediately following distractor appearance These findings provide a clear demonstration of attention being captured and captivated by a distractor that is entirely irrelevant to any attentional settings of the task.

Coupled forward-backward trajectory approach for nonequilibrium electron-ion dynamics

Science.gov (United States)

Sato, Shunsuke A.; Kelly, Aaron; Rubio, Angel

2018-04-01

We introduce a simple ansatz for the wave function of a many-body system based on coupled forward and backward propagating semiclassical trajectories. This method is primarily aimed at, but not limited to, treating nonequilibrium dynamics in electron-phonon systems. The time evolution of the system is obtained from the Euler-Lagrange variational principle, and we show that this ansatz yields Ehrenfest mean-field theory in the limit that the forward and backward trajectories are orthogonal, and in the limit that they coalesce. We investigate accuracy and performance of this method by simulating electronic relaxation in the spin-boson model and the Holstein model. Although this method involves only pairs of semiclassical trajectories, it shows a substantial improvement over mean-field theory, capturing quantum coherence of nuclear dynamics as well as electron-nuclear correlations. This improvement is particularly evident in nonadiabatic systems, where the accuracy of this coupled trajectory method extends well beyond the perturbative electron-phonon coupling regime. This approach thus provides an attractive route forward to the ab initio description of relaxation processes, such as thermalization, in condensed phase systems.

Crucial role of dynamic linker histone binding and divalent ions for DNA accessibility and gene regulation revealed by mesoscale modeling of oligonucleosomes

Science.gov (United States)

Collepardo-Guevara, Rosana; Schlick, Tamar

2012-01-01

Monte Carlo simulations of a mesoscale model of oligonucleosomes are analyzed to examine the role of dynamic-linker histone (LH) binding/unbinding in high monovalent salt with divalent ions, and to further interpret noted chromatin fiber softening by dynamic LH in monovalent salt conditions. We find that divalent ions produce a fiber stiffening effect that competes with, but does not overshadow, the dramatic softening triggered by dynamic-LH behavior. Indeed, we find that in typical in vivo conditions, dynamic-LH binding/unbinding reduces fiber stiffening dramatically (by a factor of almost 5, as measured by the elasticity modulus) compared with rigidly fixed LH, and also the force needed to initiate chromatin unfolding, making it consistent with those of molecular motors. Our data also show that, during unfolding, divalent ions together with LHs induce linker-DNA bending and DNA–DNA repulsion screening, which guarantee formation of heteromorphic superbeads-on-a-string structures that combine regions of loose and compact fiber independently of the characteristics of the LH–core bond. These structures might be important for gene regulation as they expose regions of the DNA selectively. Dynamic control of LH binding/unbinding, either globally or locally, in the presence of divalent ions, might constitute a mechanism for regulation of gene expression. PMID:22790986

Multi-Dielectric Brownian Dynamics and Design-Space-Exploration Studies of Permeation in Ion Channels.

Science.gov (United States)

Siksik, May; Krishnamurthy, Vikram

2017-09-01

This paper proposes a multi-dielectric Brownian dynamics simulation framework for design-space-exploration (DSE) studies of ion-channel permeation. The goal of such DSE studies is to estimate the channel modeling-parameters that minimize the mean-squared error between the simulated and expected "permeation characteristics." To address this computational challenge, we use a methodology based on statistical inference that utilizes the knowledge of channel structure to prune the design space. We demonstrate the proposed framework and DSE methodology using a case study based on the KcsA ion channel, in which the design space is successfully reduced from a 6-D space to a 2-D space. Our results show that the channel dielectric map computed using the framework matches with that computed directly using molecular dynamics with an error of 7%. Finally, the scalability and resolution of the model used are explored, and it is shown that the memory requirements needed for DSE remain constant as the number of parameters (degree of heterogeneity) increases.

Capture into resonance and phase-space dynamics in an optical centrifuge

Science.gov (United States)

Armon, Tsafrir; Friedland, Lazar

2016-04-01

The process of capture of a molecular ensemble into rotational resonance in the optical centrifuge is investigated. The adiabaticity and phase-space incompressibility are used to find the resonant capture probability in terms of two dimensionless parameters P1 ,2 characterizing the driving strength and the nonlinearity, and related to three characteristic time scales in the problem. The analysis is based on the transformation to action-angle variables and the single resonance approximation, yielding reduction of the three-dimensional rotation problem to one degree of freedom. The analytic results for capture probability are in good agreement with simulations. The existing experiments satisfy the validity conditions of the theory.

A dynamic mathematical model for packed columns in carbon capture plants

DEFF Research Database (Denmark)

Gaspar, Jozsef; Jørgensen, John Bagterp; Fosbøl, Philip Loldrup

2015-01-01

simulation using monoethanolamine (MEA) and piperazine (PZ) as solvent. MEA is considered as the base-case solvent in the carbon capture business. The effect of changes in the flue gas flow rate and changes in the available steam are investigated to determine their influence on the performance of the capture...

Influence of plasma density and plasma sheath dynamics on the ion implantation by plasma immersion technique

OpenAIRE

Ensinger, Wolfgang

1996-01-01

Influence of plasma density and plasma sheath dynamics on the ion implantation by plasma immersion technique / B. Rauschenbach ... - In: Nuclear instruments and methods in physics research. B. 113. 1996. S. 266-269

New source of MeV negative ion and neutral atom beams

International Nuclear Information System (INIS)

Ter-Avetisyan, S.; Braenzel, J.; Schnürer, M.; Prasad, R.; Borghesi, M.; Jequier, S.; Tikhonchuk, V.

2016-01-01

The scenario of “electron-capture and -loss” was recently proposed for the formation of negative ion and neutral atom beams with MeV kinetic energies. However, it does not explain why the formation of negative ions in a liquid spray is much more efficient than with an isolated atom. The role of atomic excited states in the charge-exchange processes is considered, and it is shown that it cannot account for the observed phenomena. The processes are more complex than the single electron-capture and -loss approach. It is suggested that the shell effects in the electronic structure of the projectile ion and/or target atoms may influence the capture/loss probabilities

New source of MeV negative ion and neutral atom beams

Energy Technology Data Exchange (ETDEWEB)

Ter-Avetisyan, S., E-mail: sargis@gist.ac.kr [Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712 (Korea, Republic of); Department of Physics and Photon Science, GIST, Gwangju 500-712 (Korea, Republic of); Braenzel, J.; Schnürer, M. [Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Berlin 12489 (Germany); Prasad, R. [Institute for Laser and Plasma Physics, Heinrich Heine University, Duesseldorf 40225 (Germany); Borghesi, M. [School of Mathematics and Physics, The Queen’s University of Belfast, Belfast BT7-1NN (United Kingdom); Jequier, S.; Tikhonchuk, V. [Centre Lasers Intenses et Applications, CEA, CNRS, University of Bordeaux, 33405 Talence (France)

2016-02-15

The scenario of “electron-capture and -loss” was recently proposed for the formation of negative ion and neutral atom beams with MeV kinetic energies. However, it does not explain why the formation of negative ions in a liquid spray is much more efficient than with an isolated atom. The role of atomic excited states in the charge-exchange processes is considered, and it is shown that it cannot account for the observed phenomena. The processes are more complex than the single electron-capture and -loss approach. It is suggested that the shell effects in the electronic structure of the projectile ion and/or target atoms may influence the capture/loss probabilities.

Classical molecular dynamics simulation of weakly-bound projectile heavy-ion reactions

Directory of Open Access Journals (Sweden)

Morker Mitul R.

2015-01-01

Full Text Available A 3-body classical molecular dynamics approach for heavy-ion reactions involving weakly bound projectiles is developed. In this approach a weakly bound projectile is constructed as a two-body cluster of the constituent tightly bound nuclei in a configuration corresponding to the observed breakup energy. This 3-body system with their individual nucleon configuration in their ground state is dynamically evolved for given initial conditions using the three-stage classical molecular dynamics approach (3S-CMD. Various levels of rigidbody constraints on the projectile constituents and the target are considered at appropriate stages. This 3-dimensional approach explicitly takes into account not only the long range Coulomb reorientation of the deformed collision partner but internal excitations and breakup probabilities at distances close to the barrier also. Dynamical simulations of 6Li+209Bi show all the possible reaction mechanism like complete fusion, incomplete fusion, scattering and breakup scattering. Complete fusion cross sections of 6Li+209Bi and 7Li+209Bi reactions are calculated in this approach with systematic relaxations of the rigid-body constraints on one or more constituent nuclei.

Charge transfer and excitation in high-energy ion-atom collisions

International Nuclear Information System (INIS)

Schlachter, A.S.; Berkner, K.H.; McDonald, R.J.

1986-11-01

Coincidence measurements of charge transfer and simultaneous projectile electron excitation provide insight into correlated two-electron processes in energetic ion-atom collisions. Projectile excitation and electron capture can occur simultaneously in a collision of a highly charged ion with a target atom; this process is called resonant transfer and excitation (RTE). The intermediate excited state which is thus formed can subsequently decay by photon emission or by Auger-electron emission. Results are shown for RTE in both the K shell of Ca ions and the L shell of Nb ions, for simultaneous projectile electron loss and excitation, and for the effect of RTE on electron capture

Ab initio molecular dynamics approach to a quantitative description of ion pairing in water

Czech Academy of Sciences Publication Activity Database

Pluhařová, Eva; Maršálek, Ondřej; Schmidt, B.; Jungwirth, Pavel

2013-01-01

Roč. 4, č. 23 (2013), s. 4177-4181 ISSN 1948-7185 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : ion pairing * charge transfer * water * ab initio molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.687, year: 2013

Background suppression by the DRAGON radiative capture facility at TRIUMF/ISAC

International Nuclear Information System (INIS)

Hutcheon, D.; Buchmann, L.; Chen, A.A.; D'Auria, J.M.; Davis, C.A.; Greife, U.; Hussein, A.; Ottewell, D.F.; Ouellet, C.V.; Parikh, A.; Parker, P.; Pearson, J.; Ruiz, C.; Ruprecht, G.; Trinczek, M.; Vockenhuber, C.

2008-01-01

The DRAGON facility at TRIUMF/ISAC detects reaction products following radiative capture of a hydrogen or helium target nucleus by an accelerated heavy ion. Capture reactions of interest in nuclear astrophysics may have reaction rates 10-14 orders of magnitude lower than the intensity of the incident beam: as well as efficiently transporting the heavy reaction product from the target to a suitable particle detector, the separator must provide most of the suppression of unreacted beam. We describe the features of beam background encountered in a range of proton- and alpha-capture experiments at the DRAGON facility.

Ejection of solvated ions from electrosprayed methanol/water nanodroplets studied by molecular dynamics simulations.

Science.gov (United States)

Ahadi, Elias; Konermann, Lars

2011-06-22

The ejection of solvated small ions from nanometer-sized droplets plays a central role during electrospray ionization (ESI). Molecular dynamics (MD) simulations can provide insights into the nanodroplet behavior. Earlier MD studies have largely focused on aqueous systems, whereas most practical ESI applications involve the use of organic cosolvents. We conduct simulations on mixed water/methanol droplets that carry excess NH(4)(+) ions. Methanol is found to compromise the H-bonding network, resulting in greatly increased rates of ion ejection and solvent evaporation. Considerable differences in the water and methanol escape rates cause time-dependent changes in droplet composition. Segregation occurs at low methanol concentration, such that layered droplets with a methanol-enriched periphery are formed. This phenomenon will enhance the partitioning of analyte molecules, with possible implications for their ESI efficiencies. Solvated ions are ejected from the tip of surface protrusions. Solvent bridging prior to ion secession is more extensive for methanol/water droplets than for purely aqueous systems. The ejection of solvated NH(4)(+) is visualized as diffusion-mediated escape from a metastable basin. The process involves thermally activated crossing of a ~30 kJ mol(-1) free energy barrier, in close agreement with the predictions of the classical ion evaporation model.

Ion dynamics in porous carbon electrodes in supercapacitors using in situ infrared spectroelectrochemistry.

Science.gov (United States)

Richey, Francis W; Dyatkin, Boris; Gogotsi, Yury; Elabd, Yossef A

2013-08-28

Electrochemical double layer capacitors (EDLCs), or supercapacitors, rely on electrosorption of ions by porous carbon electrodes and offer a higher power and a longer cyclic lifetime compared to batteries. Ionic liquid (IL) electrolytes can broaden the operating voltage window and increase the energy density of EDLCs. Herein, we present direct measurements of the ion dynamics of 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide in an operating EDLC with electrodes composed of porous nanosized carbide-derived carbons (CDCs) and nonporous onion-like carbons (OLCs) with the use of in situ infrared spectroelectrochemistry. For CDC electrodes, IL ions (both cations and anions) were directly observed entering and exiting CDC nanopores during charging and discharging of the EDLC. Conversely, for OLC electrodes, IL ions were observed in close proximity to the OLC surface without any change in the bulk electrolyte concentration during charging and discharging of the EDLC. This provides experimental evidence that charge is stored on the surface of OLCs in OLC EDLCs without long-range ion transport through the bulk electrode. In addition, for CDC EDLCs with mixed electrolytes of IL and propylene carbonate (PC), the IL ions were observed entering and exiting CDC nanopores, while PC entrance into the nanopores was IL concentration dependent. This work provides direct experimental confirmation of EDLC charging mechanisms that previously were restricted to computational simulations and theories. The experimental measurements presented here also provide deep insights into the molecular level transport of IL ions in EDLC electrodes that will impact the design of the electrode materials' structure for electrical energy storage.

Ion dynamics in moltmolti melkaltal nitrates

International Nuclear Information System (INIS)

Kamiyama, Takashi; Nakamura, Yoshio; Shibata, Kaoru; Suzuki, Kenji.

1993-01-01

Quasielastic neutron scattering experiments have been performed on simple molten alkali metal nitrates, RbNO 3 and LiNO 3 . The experiments were carried out by the medium resolution inverted geometry spectrometer LAM-40 at KENS neutron scattering facility in Japan. The measured spectra are composed of narrow and broad quasielastic spectra. We assigned that the broad component corresponds to the fast intra-ionic motions in a nitrate ion. From momentum dependence of integrated intensity for this component it is found that the motion of nitrate ions in RbNO 3 melt is mainly the librational one centered C 3 axis on the ion. On the other hand the intra-ionic motion in LiNo 3 is the librational motion cnetered C 3 axis on the nitrate ion which amplitude is smaller than in RbNO 3 melt. This fact shows that the motion of nitrate ions in LiNO 3 is restricted strongly by surrounding cations. (author)

Commercial Capabilities and Entrepreneurial Value Capturing in Dynamic Maritime Markets

DEFF Research Database (Denmark)

Sløk-Madsen, Stefan Kirkegaard

This paper develops and tests a theory of entrepreneurial value capturing in maritime markets. The framework is argued to be applicable in all maritime fields and other fields with similar attributes but is specifically tested on Oil Service companies operating in the North Sea region...... market process view; building on Kirznerian alertness, Hayekian capital heterogeneity, and Knightian uncertainty. The theory helps explain value capturing from a firm perspective but also subsequent new firm creation or value loss. The model is tested and relevant managerial implications, as well...

Fast ion-atom and ion-molecule collisions

CERN Document Server

2013-01-01

The principal goal of this book is to provide state-of-the art coverage of the non-relativistic three- and four-body theories at intermediate and high energy ion-atom and ion-molecule collisions. The focus is on the most frequently studied processes: electron capture, ionization, transfer excitation and transfer ionization. The content is suitable both for graduate students and experienced researchers. For these collisions, the literature has seen enormous renewal of activity in the development and applications of quantum-mechanical theories. This subject is of relevance in several branches of science and technology, like accelerator-based physics, the search for new sources of energy and high temperature fusion of light ions. Other important applications are in life sciences via medicine, where high-energy ion beams are used in radiotherapy for which a number of storage ring accelerators are in full operation, under construction or planned to be built worldwide. Therefore, it is necessary to review this fiel...

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

International Nuclear Information System (INIS)

Voitkiv, A B

2008-01-01

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

Propensity rules for orientation in singly-charged ion-atom collisions

International Nuclear Information System (INIS)

Nielsen, S.E.; Dubois, A.; Hansen, J.P.

1990-01-01

Orientation effects for electron capture and excitation in singly-charged ion-atom collisions are analysed using the atomic basis impact parameter method with full inclusion of electron translational factors. We find that the orientation preferences previously predicted for excitation in terms of propensity rules may still be observed when capture is present in ion-atom collisions. Furthermore, in spite of intricate behaviour of the direct capture couplings during the collision, we draw some parallel conclusions for the orientation of the capture states. We illustrate these perturbative predictions by close-coupling calculations for H + -Na(3s) collisions where clear propensity for orientation of the H(2p) capture state is demonstrated in impact parameter and velocity dependences. Finally we predict pronounced orientation effects for H(2s) and H(2p) capture in collisions of H + with initially oriented Na(3p) states. (author)

A hybrid gyrokinetic ion and isothermal electron fluid code for astrophysical plasma

Science.gov (United States)

Kawazura, Y.; Barnes, M.

2018-05-01

This paper describes a new code for simulating astrophysical plasmas that solves a hybrid model composed of gyrokinetic ions (GKI) and an isothermal electron fluid (ITEF) Schekochihin et al. (2009) [9]. This model captures ion kinetic effects that are important near the ion gyro-radius scale while electron kinetic effects are ordered out by an electron-ion mass ratio expansion. The code is developed by incorporating the ITEF approximation into AstroGK, an Eulerian δf gyrokinetics code specialized to a slab geometry Numata et al. (2010) [41]. The new code treats the linear terms in the ITEF equations implicitly while the nonlinear terms are treated explicitly. We show linear and nonlinear benchmark tests to prove the validity and applicability of the simulation code. Since the fast electron timescale is eliminated by the mass ratio expansion, the Courant-Friedrichs-Lewy condition is much less restrictive than in full gyrokinetic codes; the present hybrid code runs ∼ 2√{mi /me } ∼ 100 times faster than AstroGK with a single ion species and kinetic electrons where mi /me is the ion-electron mass ratio. The improvement of the computational time makes it feasible to execute ion scale gyrokinetic simulations with a high velocity space resolution and to run multiple simulations to determine the dependence of turbulent dynamics on parameters such as electron-ion temperature ratio and plasma beta.

Development of a tool to capture of the human movement for biometric analysis

International Nuclear Information System (INIS)

Chacon Taylor, Marco; Ortiz Cubero, Esteban

2013-01-01

A tool is developed for the measurement of stability static and dynamic of people. The Wii Remote TM was chosen as the system to capture body movement. The measurements of the gyroscopes and accelerometers are obtained from the wiimote adhered to a part of the human body. Dynamic stability parameters are calculated using the wiimote. Dynamic stability data are compared between IMU (Inertial Measurement Unit) and wiimote. The position, orientation, etc. are recreated from measurements of the wiimote. The study of new motion capture techniques is recommended for the analysis of dynamic stability [es

How can you capture cultural dynamics?

Directory of Open Access Journals (Sweden)

Yoshihisa eKashima

2014-09-01

Full Text Available Cross-cultural comparison is a critical method by which we can examine the interaction between culture and psychological processes. However, comparative methods tend to overlook cultural dynamics – the formation, maintenance, and transformation of cultures over time. The present article gives a brief overview of four different types of research designs that have been used to examine cultural dynamics in the literature: (1 cross-temporal methods that trace medium- to long-term changes in a culture; (2 cross-generational methods that explore medium-term implications of cultural transmission; (3 experimental simulation methods that investigate micro-level mechanisms of cultural dynamics; and (4 formal models and computer simulation methods often used to investigate long-term and macro-level implications of micro-level mechanisms. These methods differ in terms of level of analysis for which they are designed (micro vs. macro-level, scale of time for which they are typically used (short-, medium-, or long-term, and direction of inference (deductive vs. empirical method that they imply. The paper describes examples of these methods, discuss their strengths and weaknesses, and point to their complementarity in inquiries about cultural change. Because cultural dynamics research is about meaning over time, issues deriving from interpretation of meaning and temporal distance between researchers and objects of inquiry can pose threats to the validity of the research and its findings. The methodological question about hermeneutic circle is recalled and further inquiries are encouraged.

How can you capture cultural dynamics?

Science.gov (United States)

Kashima, Yoshihisa

2014-01-01

Cross-cultural comparison is a critical method by which we can examine the interaction between culture and psychological processes. However, comparative methods tend to overlook cultural dynamics – the formation, maintenance, and transformation of cultures over time. The present article gives a brief overview of four different types of research designs that have been used to examine cultural dynamics in the literature: (1) cross-temporal methods that trace medium- to long-term changes in a culture; (2) cross-generational methods that explore medium-term implications of cultural transmission; (3) experimental simulation methods that investigate micro-level mechanisms of cultural dynamics; and (4) formal models and computer simulation methods often used to investigate long-term and macro-level implications of micro-level mechanisms. These methods differ in terms of level of analysis for which they are designed (micro vs. macro-level), scale of time for which they are typically used (short-, medium-, or long-term), and direction of inference (deductive vs. empirical method) that they imply. The paper describes examples of these methods, discuss their strengths and weaknesses, and point to their complementarity in inquiries about cultural change. Because cultural dynamics research is about meaning over time, issues deriving from interpretation of meaning and temporal distance between researchers and objects of inquiry can pose threats to the validity of the research and its findings. The methodological question about hermeneutic circle is recalled and further inquiries are encouraged. PMID:25309476

CHAOTIC CAPTURE OF NEPTUNE TROJANS

International Nuclear Information System (INIS)

Nesvorny, David; Vokrouhlicky, David

2009-01-01

Neptune Trojans (NTs) are swarms of outer solar system objects that lead/trail planet Neptune during its revolutions around the Sun. Observations indicate that NTs form a thick cloud of objects with a population perhaps ∼10 times more numerous than that of Jupiter Trojans and orbital inclinations reaching ∼25 deg. The high inclinations of NTs are indicative of capture instead of in situ formation. Here we study a model in which NTs were captured by Neptune during planetary migration when secondary resonances associated with the mean-motion commensurabilities between Uranus and Neptune swept over Neptune's Lagrangian points. This process, known as chaotic capture, is similar to that previously proposed to explain the origin of Jupiter's Trojans. We show that chaotic capture of planetesimals from an ∼35 Earth-mass planetesimal disk can produce a population of NTs that is at least comparable in number to that inferred from current observations. The large orbital inclinations of NTs are a natural outcome of chaotic capture. To obtain the ∼4:1 ratio between high- and low-inclination populations suggested by observations, planetary migration into a dynamically excited planetesimal disk may be required. The required stirring could have been induced by Pluto-sized and larger objects that have formed in the disk.

Ion Dynamics Study of Potato Starch + Sodium Salts Electrolyte System

Directory of Open Access Journals (Sweden)

Tuhina Tiwari

2013-01-01

Full Text Available The effect of different anions, namely, SCN−, I−, and ClO4−, on the electrical properties of starch-based polymer electrolytes has been studied. Anion size and conductivity are having an inverse trend indicating systems to be predominantly anionic conductor. Impact of anion size and multiplet forming tendency is reflected in number of charge carriers and mobility, respectively. Ion dynamics study reveals the presence of different mechanisms in different frequency ranges. Interestingly, superlinear power law (SLPL is found to be present at <5 MHz frequency, which is further confirmed by dielectric data.

Transition to Collisionless Ion-Temperature-Gradient-Driven Plasma Turbulence: A Dynamical Systems Approach

International Nuclear Information System (INIS)

Kolesnikov, R.A.; Krommes, J.A.

2005-01-01

The transition to collisionless ion-temperature-gradient-driven plasma turbulence is considered by applying dynamical systems theory to a model with 10 degrees of freedom. The study of a four-dimensional center manifold predicts a 'Dimits shift' of the threshold for turbulence due to the excitation of zonal flows and establishes (for the model) the exact value of that shift

Molecular dynamic simulation of interaction of low-energy Ar and Xe ions with copper clusters at graphite surface

International Nuclear Information System (INIS)

Kornich, G.V.; Lozovskaya, L.I.; Betts, G.; Zaporozhchenko, V.I.; Faupel, F.

2005-01-01

One conducted molecular and dynamic simulation of sputtering of isolated clusters consisting of 13, 27 and 195 Cu atoms from the (0001) graphite surface by 200 eV energy Ar and Xe ions. It is shown that the factors of reflection of Ar and Xe ions from copper clusters differ from one another insignificantly, though the energy of the reflected Xe ions is essentially lower than that of Ar ions. The values of the factor of cluster sputtering by Xe ions are higher in contrast to sputtering by Ar ions. One identified two mechanisms of cluster sputtering resulting in the maximum of sputtering intensity at the polar angles near the normal one, and in periodicity of maximums within the azimuth distributions of sputtering intensity with 60 deg period [ru

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

Energy Technology Data Exchange (ETDEWEB)

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

1998-05-14

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

Energy landscapes for mobile ions in ion conducting solids

Indian Academy of Sciences (India)

molecular dynamics (MD) simulations yields quantitative predictions of the ion transport characteristics. As ... Solid electrolytes; bond valence analysis; ion transport in glasses. 1. .... clusters are considered to contribute only to a.c. conduc-.

High-precision spectrometer for studies of ion-induced and spontaneous fission dynamics

International Nuclear Information System (INIS)

Batenkov, O.; Elmgren, K.; Majorov, M.; Blomgren, J.; Conde, H.; Hultqvist, S.; Olsson, N.; Rahm, J.; Ramstroem, E.; Smirnov, S.; Veshikov, A.

1997-01-01

A spectrometer has been designed and built to investigate the dynamics of spontaneous and ion-induced fission processes. It consists of 8 neutron detectors surrounding a low mass scattering chamber containing the fissionable targets and two fission fragment telescopes. The spectrometer measures neutron spectra, and energy and angular correlations of neutrons, as well as kinetic energy, mass, and relative angle of fission fragments. A 252 Cf fission reference source is used for calibration. (orig.)

Charge steering of laser plasma accelerated fast ions in a liquid spray — creation of MeV negative ion and neutral atom beams

International Nuclear Information System (INIS)

Schnürer, M.; Abicht, F.; Priebe, G.; Braenzel, J.; Prasad, R.; Borghesi, M.; Andreev, A.; Nickles, P. V.; Jequier, S.; Tikhonchuk, V.; Ter-Avetisyan, S.

2013-01-01

The scenario of “electron capture and loss” has been recently proposed for the formation of negative ion and neutral atom beams with up to MeV kinetic energy [S. Ter-Avetisyan, et al., Appl. Phys. Lett. 99, 051501 (2011)]. Validation of these processes and of their generic nature is here provided in experiments where the ion source and the interaction medium have been spatially separated. Fast positive ions accelerated from a laser plasma source are sent through a cold spray where their charge is changed. Such formed neutral atom or negative ion has nearly the same momentum as the original positive ion. Experiments are released for protons, carbon, and oxygen ions and corresponding beams of negative ions and neutral atoms have been obtained. The electron capture and loss phenomenon is confirmed to be the origin of the negative ion and neutral atom beams. The equilibrium ratios of different charge components and cross sections have been measured. Our method is general and allows the creation of beams of neutral atoms and negative ions for different species which inherit the characteristics of the positive ion source

Low energy ion-molecule reaction dynamics and chemiionization kinetics: Progress report, February 1, 1985-January 31, 1988

International Nuclear Information System (INIS)

Farrar, J.M.

1988-01-01

The research program at Rochester is devoted to an understanding of the dynamics of elementary gas phase ionic reactions by using the molecular beam methods. We seek to elucidate pathways for energy disposal in elementary reactions, with the goal of using this information to understand the topology of the potential surfaces which govern the reaction, applying the results to ionic channels in combustion systems. We have made significant accomplishments in several distinct areas of research in crossed beam studies of ion-neutral reaction dynamics in the past three years. Our research has focused on the following topics and has resulted in 15 publications and submissions to major journals, with several additional manuscripts in preparation: dynamics of gas phase proton transfer reactions, gas phase carbon and methyl cation chemistry, reactive scattering from double minimum potentials, reactions of highly vibrationally excited ions: NH 3 + + D 2 , and electron and proton transfer reactions of anions. 9 refs

Non-Markovian dynamics of quantum systems: decay rate, capture and pure states

International Nuclear Information System (INIS)

Kanokov, Z.; Palchikov, Yu.V.; Antonenko, N.V.; Adamian, G.G.; Kanokov, Z.; Adamian, G.G.; Scheid, W.

2004-01-01

Full text: With the exact numerical solution of the equation for the reduced density matrix we found a minor role of the time dependence of the friction and diffusion coefficients in the escape rate from a potential well [1]. Since the used friction and diffusion coefficients were self- consistently under certain approximations derived, they preserve the positivity of the density matrix at any time. The mixed diffusion coefficient leads to a decrease of the escape rate. Since the used value of quantum diffusion coefficient in momentum is larger than the one following from a 'classic' treatment, the obtained escape rate is close to the rate calculated with the 'classic' set of diffusion coefficients. If the regime of motion is close to the under damped case or the temperature is small, the quasi-stationary escape rate can increase with friction. This is explained by the larger role of the increasing diffusion in the decay process. The agreement of the escape rate obtained with the analytical expressions in comparison to numerically calculated data depends on the characteristics of the considered system. The agreement is better in the overdamped regime. However, for any regime the deviations are not larger than in the case of the classical Kramers formula. Therefore, the analytical expressions can be applied in a large range of parameters for the potential and diffusion coefficients. We demonstrated that the uncertainty function is related to the linear entropy. The diffusion coefficients supplying the purity of states were elaborated for the non-Markovian dynamics. The obtained dependences of the capture probability on the friction proves that the quantum nature of this process should be taken into consideration when one calculates the capture cross section in nucleus-nucleus collisions

Resonant Ion Pair Formation in Electron Collisions with Ground State Molecular Ions

International Nuclear Information System (INIS)

Zong, W.; Dunn, G.H.; Djuric, N.; Greene, C.H.; Neau, A.; Zong, W.; Larsson, M.; Al-Khalili, A.; Neau, A.; Derkatch, A.M.; Vikor, L.; Shi, W.; Rosen, S.; Le Padellec, A.; Danared, H.; Ugglas, M. af

1999-01-01

Resonant ion pair formation from collisions of electrons with ground state diatomic molecular ions has been observed and absolute cross sections measured. The cross section for HD + is characterized by an abrupt threshold at 1.9thinspthinspeV and 14 resolved peaks in the range of energies 0≤E≤14 eV . The dominant mechanism responsible for the structures appears to be resonant capture and stabilization, modified by two-channel quantum interference. Data on HF + show structure correlated with photoionization of HF and with dissociative recombination of electrons with this ion. copyright 1999 The American Physical Society

History-dependent dynamics in a generic model of ion channels - an analytic study

Directory of Open Access Journals (Sweden)

Daniel Soudry

2010-04-01

Full Text Available Recent experiments have demonstrated that the timescale of adaptation of single neurons and ion channel populations to stimuli slows down as the length of stimulation increases; in fact, no upper bound on temporal time-scales seems to exist in such systems. Furthermore, patch clamp experiments on single ion channels have hinted at the existence of large, mostly unobservable, inactivation state spaces within a single ion channel. This raises the question of the relation between this multitude of inactivation states and the observed behavior. In this work we propose a minimal model for ion channel dynamics which does not assume any specific structure of the inactivation state space. The model is simple enough to render an analytical study possible. This leads to a clear and concise explanation of the experimentally observed exponential history-dependent relaxation in sodium channels in a voltage clamp setting, and shows that their recovery rate from slow inactivation must be voltage dependent. Furthermore, we predict that history-dependent relaxation cannot be created by overly sparse spiking activity. While the model was created with ion channel populations in mind, its simplicity and genericalness render it a good starting point for modeling similar effects in other systems, and for scaling up to higher levels such as single neurons which are also known to exhibit multiple time scales.

Dynamically biased statistical model for the ortho/para conversion in the H2 + H3+ → H3+ + H2 reaction

OpenAIRE

Gómez-Carrasco, Susana; González-Sánchez, Lola; Aguado, Alfredo; Sanz-Sanz, Cristina; Zanchet, Alexandre; Roncero, Octavio

2012-01-01

In this work we present a dynamically biased statistical model to describe the evolution of the title reaction from statistical to a more direct mechanism, using quasi-classical trajectories (QCT). The method is based on the one previously proposed by Park and Light [J. Chem. Phys. 126, 044305 (2007)10.1063/1.2430711]. A recent global potential energy surface is used here to calculate the capture probabilities, instead of the long-range ion-induced dipole interactions. The dynamical constrain...

Langevin Dynamics with Spatial Correlations as a Model for Electron-Phonon Coupling

Science.gov (United States)

Tamm, A.; Caro, M.; Caro, A.; Samolyuk, G.; Klintenberg, M.; Correa, A. A.

2018-05-01

Stochastic Langevin dynamics has been traditionally used as a tool to describe nonequilibrium processes. When utilized in systems with collective modes, traditional Langevin dynamics relaxes all modes indiscriminately, regardless of their wavelength. We propose a generalization of Langevin dynamics that can capture a differential coupling between collective modes and the bath, by introducing spatial correlations in the random forces. This allows modeling the electronic subsystem in a metal as a generalized Langevin bath endowed with a concept of locality, greatly improving the capabilities of the two-temperature model. The specific form proposed here for the spatial correlations produces a physical wave-vector and polarization dependency of the relaxation produced by the electron-phonon coupling in a solid. We show that the resulting model can be used for describing the path to equilibration of ions and electrons and also as a thermostat to sample the equilibrium canonical ensemble. By extension, the family of models presented here can be applied in general to any dense system, solids, alloys, and dense plasmas. As an example, we apply the model to study the nonequilibrium dynamics of an electron-ion two-temperature Ni crystal.

Simultaneous ion and neutral evaporation in aqueous nanodrops: experiment, theory, and molecular dynamics simulations.

Science.gov (United States)

Higashi, Hidenori; Tokumi, Takuya; Hogan, Christopher J; Suda, Hiroshi; Seto, Takafumi; Otani, Yoshio

2015-06-28

We use a combination of tandem ion mobility spectrometry (IMS-IMS, with differential mobility analyzers), molecular dynamics (MD) simulations, and analytical models to examine both neutral solvent (H2O) and ion (solvated Na(+)) evaporation from aqueous sodium chloride nanodrops. For experiments, nanodrops were produced via electrospray ionization (ESI) of an aqueous sodium chloride solution. Two nanodrops were examined in MD simulations: a 2500 water molecule nanodrop with 68 Na(+) and 60 Cl(-) ions (an initial net charge of z = +8), and (2) a 1000 water molecule nanodrop with 65 Na(+) and 60 Cl(-) ions (an initial net charge of z = +5). Specifically, we used MD simulations to examine the validity of a model for the neutral evaporation rate incorporating both the Kelvin (surface curvature) and Thomson (electrostatic) influences, while both MD simulations and experimental measurements were compared to predictions of the ion evaporation rate equation of Labowsky et al. [Anal. Chim. Acta, 2000, 406, 105-118]. Within a single fit parameter, we find excellent agreement between simulated and modeled neutral evaporation rates for nanodrops with solute volume fractions below 0.30. Similarly, MD simulation inferred ion evaporation rates are in excellent agreement with predictions based on the Labowsky et al. equation. Measurements of the sizes and charge states of ESI generated NaCl clusters suggest that the charge states of these clusters are governed by ion evaporation, however, ion evaporation appears to have occurred with lower activation energies in experiments than was anticipated based on analytical calculations as well as MD simulations. Several possible reasons for this discrepancy are discussed.

Three-Dimensional Dynamics of Breakout Afterburner Ion Acceleration Using High-Contrast Short-Pulse Laser and Nanoscale Targets

International Nuclear Information System (INIS)

Yin, L.; Albright, B. J.; Bowers, K. J.; Fernandez, J. C.; Jung, D.; Hegelich, B. M.

2011-01-01

Breakout afterburner (BOA) laser-ion acceleration has been demonstrated for the first time in the laboratory. In the BOA, an initially solid-density target undergoes relativistically induced transparency, initiating a period of enhanced ion acceleration. First-ever kinetic simulations of the BOA in three dimensions show that the ion beam forms lobes in the direction orthogonal to laser polarization and propagation. Analytic theory presented for the electron dynamics in the laser ponderomotive field explains how azimuthal symmetry breaks even for a symmetric laser intensity profile; these results are consistent with recent experiments at the Trident laser facility.

Micromotors to capture and destroy anthrax simulant spores.

Science.gov (United States)

Orozco, Jahir; Pan, Guoqing; Sattayasamitsathit, Sirilak; Galarnyk, Michael; Wang, Joseph

2015-03-07

Towards addressing the need for detecting and eliminating biothreats, we describe a micromotor-based approach for screening, capturing, isolating and destroying anthrax simulant spores in a simple and rapid manner with minimal sample processing. The B. globilli antibody-functionalized micromotors can recognize, capture and transport B. globigii spores in environmental matrices, while showing non-interactions with excess of non-target bacteria. Efficient destruction of the anthrax simulant spores is demonstrated via the micromotor-induced mixing of a mild oxidizing solution. The new micromotor-based approach paves a way to dynamic multifunctional systems that rapidly recognize, isolate, capture and destroy biological threats.

Two-electron excitation in slow ion-atom collisions: Excitation mechanisms and interferences among autoionizing states

International Nuclear Information System (INIS)

Kimura, M.; Rice Univ., Houston, TX

1990-01-01

The two-electron capture or excitation process resulting from collisions of H + and O 6+ ions with He atoms in the energy range from 0.5 keV/amu to 5 keV/amu is studied within a molecular representation. The collision dynamics for formation of doubly excited O 4+ ions and He** atoms and their (n ell, n'ell ') populations are analyzed in conjunction with electron correlations. Autoionizing states thus formed decay through the Auger process. An experimental study of an ejected electron energy spectrum shows ample structures in addition to two characteristic peaks that are identified by atomic and molecular autoionizations. These structures are attributable to various interferences among electronic states and trajectories. We examine the dominant sources of the interferences. 12 refs., 5 figs

Monte Carlo simulations of silicon sputtering by argon ions and an approach for comparison with molecular dynamic results

Energy Technology Data Exchange (ETDEWEB)

Feder, Rene; Frost, Frank; Mayr, Stefan G.; Neumann, Horst; Bundesmann, Carsten [Leibniz-Institut fuer Oberflaechenmodifizierung e.V., Leipzig (Germany)

2012-07-01

Ion beam sputter processes deliver some intrinsic features influencing the growing film properties. Utilisation of these features needs to know how primary ion properties and geometrical process conditions influence the energy and spatial distribution of the sputtered and scattered particles. Beside complex experiments simulations are helpful to explain the correlation between primary parameters and thin film properties. The paper presents first results of two simulation codes with completely different approaches: Monte Carlo (MC) calculations with help of the well known TRIM.SP code and Molecular Dynamics calculations with an in-house developed code. First results of both simulation principles are compared for Argon ion bombardment on a Silicon target. Furthermore, a special experimental setup is outlined for validation of modelling. The setup allows the variation of ion beam parameters (ion species, ion energy, ion incidence angle on the target) and the measurement of the properties of sputtered and scattered particles.

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

CERN Document Server

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

2016-01-01

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

Effects of fast monoenergetic electrons on the ion dynamics near the cathode in a pulsed direct current plasma sheath

International Nuclear Information System (INIS)

Sharifian, M.; Shokri, B.

2008-01-01

A detailed one-dimensional simulation of the ion dynamics of the plasma sheath near a substrate (cathode) in the presence of fast monoenergetic electrons has been carried out in this article. The sheath evolution is investigated by using a fluid model assuming that the ions, plasma electrons and monoenergetic, fast electrons act as three fluids (fluid approach). The effect of the density of fast electrons on the ion density, ion velocity, and ion energy near the cathode and the evolution of the sheath boundary in front of the cathode are separately explored. Also, the variation of the ion velocity and ion density at the vicinity of the cathode as a function of time is investigated in the absence and presence of the electron beam. Results indicate that the presence of fast electrons in the sheath causes significant change in the sheath thickness and therefore basically changes the ion velocity, ion density, and ion impact energy on the cathode compared to the absence of the electron beam case

Near-membrane dynamics and capture of TRPM8 channels within transient confinement domains.

Directory of Open Access Journals (Sweden)

Luis A Veliz

Full Text Available BACKGROUND: The cold and menthol receptor, TRPM8, is a non-selective cation channel expressed in a subset of peripheral neurons that is responsible for neuronal detection of environmental cold stimuli. It was previously shown that members of the transient receptor potential (TRP family of ion channels are translocated toward the plasma membrane (PM in response to agonist stimulation. Because the spatial and temporal dynamics of cold receptor cell-surface residence may determine neuronal activity, we hypothesized that the movement of TRPM8 to and from the PM might be a regulated process. Single particle tracking (SPT is a useful tool for probing the organization and dynamics of protein constituents in the plasma membrane. METHODOLOGY/PRINCIPAL FINDINGS: We used SPT to study the receptor dynamics and describe membrane/near-membrane behavior of particles containing TRPM8-EGFP in transfected HEK-293T and F-11 cells. Cells were imaged using total internal reflection fluorescence (TIRF microscopy and the 2D and 3D trajectories of TRPM8 molecules were calculated by analyzing mean-square particle displacement against time. Four characteristic types of motion were observed: stationary mode, simple Brownian diffusion, directed motion, and confined diffusion. In the absence of cold or menthol to activate the channel, most TRPM8 particles move in network covering the PM, periodically lingering for 2-8 s in confined microdomains of about 800 nm radius. Removing cholesterol with methyl-beta-cyclodextrin (MβCD stabilizes TRPM8 motion in the PM and is correlated with larger TRPM8 current amplitude that results from an increase in the number of available channels without a change in open probability. CONCLUSIONS/SIGNIFICANCE: These results reveal a novel mechanism for regulating TRPM8 channel activity, and suggest that PM dynamics may play an important role in controlling electrical activity in cold-sensitive neurons.

Highly Sensitive Aluminium(III) Ion Sensor Based on a Self-assembled Monolayer on a Gold Nanoparticles Modified Screen-printed Carbon Electrode.

Science.gov (United States)

See, Wong Pooi; Heng, Lee Yook; Nathan, Sheila

2015-01-01

A new approach for the development of a highly sensitive aluminium(III) ion sensor via the preconcentration of aluminium(III) ion with a self-assembled monolayer on a gold nanoparticles modified screen-printed carbon electrode and current mediation by potassium ferricyanide redox behavior during aluminium(III) ion binding has been attempted. A monolayer of mercaptosuccinic acid served as an effective complexation ligand for the preconcentration of trace aluminium; this led to an enhancement of aluminium(III) ion capture and thus improved the sensitivity of the sensor with a detection limit of down to the ppb level. Under the optimum experimental conditions, the sensor exhibited a wide linear dynamic range from 0.041 to 12.4 μM. The lower detection limit of the developed sensor was 0.037 μM (8.90 ppb) using a 10 min preconcentration time. The sensor showed excellent selectivity towards aluminium(III) ion over other interference ions.

Structure and dynamics of ion clusters in linear octupole traps: Phase diagrams, chirality, and melting mechanisms

International Nuclear Information System (INIS)

Yurtsever, E.; Onal, E. D.; Calvo, F.

2011-01-01

The stable structures and melting dynamics of clusters of identical ions bound by linear octupole radiofrequency traps are theoretically investigated by global optimization methods and molecular dynamics simulations. By varying the cluster sizes in the range of 10-1000 ions and the extent of trap anisotropy by more than one order of magnitude, we find a broad variety of stable structures based on multiple rings at small sizes evolving into tubular geometries at large sizes. The binding energy of these clusters is well represented by two contributions arising from isotropic linear and octupolar traps. The structures generally exhibit strong size effects, and chiral arrangements spontaneously emerge in many crystals. Sufficiently large clusters form nested, coaxial tubes with different thermal stabilities. As in isotropic octupolar clusters, the inner tubes melt at temperatures that are lower than the overall melting point.

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

NARCIS (Netherlands)

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

1994-01-01

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

Structural and Dynamical Properties of Alkaline Earth Metal Halides in Supercritical Water: Effect of Ion Size and Concentration.

Science.gov (United States)

Keshri, Sonanki; Tembe, B L

2017-11-22

Constant temperature-constant pressure molecular dynamics simulations have been performed for aqueous alkaline earth metal chloride [M 2+ -Cl - (M = Mg, Ca, Sr, and Ba)] solutions over a wide range of concentrations (0.27-5.55 m) in supercritical (SC) and ambient conditions to investigate their structural and dynamical properties. A strong influence of the salt concentration is observed on the ion-ion pair correlation functions in both ambient and SC conditions. In SC conditions, significant clustering is observed in the 0.27 m solution, whereas the reverse situation is observed at room temperature and this is also supported by the residence times of the clusters. The concentration and ion size (cation size) seem to have opposite effects on the average number of hydrogen bonds. The simulation results show that the self-diffusion coefficients of water, cations, and the chloride ion increase with increasing temperature, whereas they decrease with increasing salt concentration. The cluster size distribution shows a strong density dependence in both ambient and SC conditions. In SC conditions, cluster sizes display a near-Gaussian distribution, whereas the distribution decays monotonically in ambient conditions.

Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions

International Nuclear Information System (INIS)

Bradforth, S.E.

1992-11-01

The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound → bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN - , NCO - and NCS - . Transition state photoelectron spectra are presented for the following systems Br + HI, Cl + HI, F + HI, F + CH 3 0H,F + C 2 H 5 OH,F + OH and F + H 2 . A time dependent framework for the simulation and interpretation of the bound → free transition state photoelectron spectra is subsequently developed and applied to the hydrogen transfer reactions Br + HI, F + OH → O( 3 P, 1 D) + HF and F + H 2 . The theoretical approach for the simulations is a fully quantum-mechanical wave packet propagation on a collinear model reaction potential surface. The connection between the wavepacket time evolution and the photoelectron spectrum is given by the time autocorrelation function. For the benchmark F + H 2 system, comparisons with three-dimensional quantum calculations are made

AMUC: Associated Motion capture User Categories.

Science.gov (United States)

Norman, Sally Jane; Lawson, Sian E M; Olivier, Patrick; Watson, Paul; Chan, Anita M-A; Dade-Robertson, Martyn; Dunphy, Paul; Green, Dave; Hiden, Hugo; Hook, Jonathan; Jackson, Daniel G

2009-07-13

The AMUC (Associated Motion capture User Categories) project consisted of building a prototype sketch retrieval client for exploring motion capture archives. High-dimensional datasets reflect the dynamic process of motion capture and comprise high-rate sampled data of a performer's joint angles; in response to multiple query criteria, these data can potentially yield different kinds of information. The AMUC prototype harnesses graphic input via an electronic tablet as a query mechanism, time and position signals obtained from the sketch being mapped to the properties of data streams stored in the motion capture repository. As well as proposing a pragmatic solution for exploring motion capture datasets, the project demonstrates the conceptual value of iterative prototyping in innovative interdisciplinary design. The AMUC team was composed of live performance practitioners and theorists conversant with a variety of movement techniques, bioengineers who recorded and processed motion data for integration into the retrieval tool, and computer scientists who designed and implemented the retrieval system and server architecture, scoped for Grid-based applications. Creative input on information system design and navigation, and digital image processing, underpinned implementation of the prototype, which has undergone preliminary trials with diverse users, allowing identification of rich potential development areas.

Physiological reactions to capture in hibernating brown bears.

Science.gov (United States)

Evans, Alina L; Singh, Navinder J; Fuchs, Boris; Blanc, Stéphane; Friebe, Andrea; Laske, Timothy G; Frobert, Ole; Swenson, Jon E; Arnemo, Jon M

2016-01-01

Human disturbance can affect animal life history and even population dynamics. However, the consequences of these disturbances are difficult to measure. This is especially true for hibernating animals, which are highly vulnerable to disturbance, because hibernation is a process of major physiological changes, involving conservation of energy during a resource-depleted time of year. During the winters of 2011-15, we captured 15 subadult brown bears ( Ursus arctos ) and recorded their body temperatures ( n  = 11) and heart rates ( n = 10) before, during and after capture using biologgers. We estimated the time for body temperature and heart rate to normalize after the capture event. We then evaluated the effect of the captures on the pattern and depth of hibernation and the day of den emergence by comparing the body temperature of captured bears with that of undisturbed subadult bears ( n  = 11). Both body temperature and heart rate increased during capture and returned to hibernation levels after 15-20 days. We showed that bears required 2-3 weeks to return to hibernation levels after winter captures, suggesting high metabolic costs during this period. There were also indications that the winter captures resulted in delayed den emergence.

Dynamic dipole polarizabilities of the Li atom and the Be+ ion

International Nuclear Information System (INIS)

Tang Liyan; Yan Zongchao; Shi Tingyun; Mitroy, J.

2010-01-01

The dynamic dipole polarizabilities for Li atoms and Be + ions in the 2 2 S and 2 2 P states are calculated using the variational method with a Hylleraas basis. The present polarizabilities represent the definitive values in the nonrelativistic limit. Corrections due to relativistic effects are also estimated. Analytic representations of the polarizabilities for frequency ranges encompassing the n=3 excitations are presented. The recommended polarizabilities for 7 Li and 9 Be + are 164.11±0.03 a 0 3 and 24.489±0.004 a 0 3 , respectively.

Dynamics of water and ions in clays of type montmorillonite by microscopic simulation and quasi-elastic neutron scattering; Dynamique de l'eau et des ions dans des argiles de type montmorillonite par simulation microscopique et diffusion quasi-elastique des neutrons

Energy Technology Data Exchange (ETDEWEB)

Malikova, N

2005-09-15

Montmorillonite clays in low hydration states, with Na{sup +} and Cs{sup +} compensating counter ions, are investigated by a combination of microscopic simulation and quasi-elastic neutron scattering to obtain information on the local structure and dynamics of water and ions in the interlayer. At first predictions of simulation into the dynamics of water and ions at elevate temperatures are shown (0 deg C 80 deg C, pertinent for the radioactive waste disposal scenario) Marked difference is observed between the modes of diffusion of the Na{sup +} and C{sup +} counter ions. In water dynamics, a significant step towards bulk water behaviour is seen on transition from the mono- to bilayer states. Secondly, a detailed comparison between simulation and quasi-elastic neutron scattering (Neutron Spin Echo and Time-of-Flight) regarding ambient temperature water dynamics is presented. Overall, the approaches are found to be in good agreement with each other and limitations of each of the methods are clearly shown. (author)

Structure and dynamics of hydrated Fe(II) and Fe(III) ions. Quantum mechanical and molecular mechanical simulations

International Nuclear Information System (INIS)

Remsungnen, T.

2002-11-01

Classical molecular dynamics (MD) and combined em ab initio quantum mechanical/molecular mechanical molecular dynamics (QM/MM-MD) simulations have been performed to investigate structural, dynamical and energetical properties of Fe(II), and Fe(III) transition metal ions in aqueous solution. In the QM/MM-MD simulations the ion and its first hydration sphere were treated at the Hartree-Fock ab initio quantum mechanical level, while ab initio generated pair plus three-body potentials were employed for the remaining system. For the classical MD simulation the pair plus three-body potential were employed for all ion-water interactions. The coordination number of the first hydration shell is 100 % of 6 in both cases. The number of waters in the second hydration shell obtained from classical simulations are 13.4 and 15.1 for Fe(II) and Fe(III), respectively, while QM/MM-MD gives the values of 12.4 and 13.4 for Fe(II) and Fe(III). The energies of hydration obtained from MD and QM/MM-MD for Fe(II) are 520 and 500 kcal/mol, and for Fe(III) 1160 and 1100 kcal/mol respectively. The mean residence times of water in the second shell obtained from QM/MM-MD are 24 and 48 ps for Fe(II) and Fe(III), respectively. In contrast to the data obtained from classical MD simulation, the QM/MM-MD values are all in good agreement with the experimental data available. These investigations and results clearly indicate that many-body effects are essential for the proper description of all properties of the aqueous solution of both Fe(II) and Fe(III) ions. (author)

Some aspects of ion implantation in semiconductors

International Nuclear Information System (INIS)

Klose, H.

1982-01-01

The advantages and disadvantages of ion implantation in the application of semiconductor technology are reviewed in short. This article describes some aspects of the state of the art and current developments of nonconventional annealing procedures, ion beam gettering of deep impurities, special applications of ion implantation using low or high energy ions and GaAs-electronics, respectively. Radiation defects in Si and the nonexponential emission and capture processes in GaAsP are discussed. Final future trends of ion beam methods in semiconductor production technology are summarized. (author)

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

International Nuclear Information System (INIS)

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

2007-01-01

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

High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams

International Nuclear Information System (INIS)

Alejo, A.; Kar, S.; Ahmed, H.; Doria, D.; Borghesi, M.; Tebartz, A.; Ding, J.; Neumann, N.; Astbury, S.; Carroll, D. C.; Scott, G. G.; Higginson, A.; McKenna, P.; Wagner, F.; Roth, M.

2016-01-01

We report on the experimental characterisation of laser-driven ion beams using a Thomson Parabola Spectrometer (TPS) equipped with trapezoidally shaped electric plates, proposed by Gwynne et al. [Rev. Sci. Instrum. 85, 033304 (2014)]. While a pair of extended (30 cm long) electric plates was able to produce a significant increase in the separation between neighbouring ion species at high energies, deploying a trapezoidal design circumvented the spectral clipping at the low energy end of the ion spectra. The shape of the electric plate was chosen carefully considering, for the given spectrometer configuration, the range of detectable ion energies and species. Analytical tracing of the ion parabolas matches closely with the experimental data, which suggests a minimal effect of fringe fields on the escaping ions close to the wedged edge of the electrode. The analytical formulae were derived considering the relativistic correction required for the high energy ions to be characterised using such spectrometer.

High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams

Energy Technology Data Exchange (ETDEWEB)

Alejo, A.; Kar, S., E-mail: s.kar@qub.ac.uk; Ahmed, H.; Doria, D.; Borghesi, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN (United Kingdom); Tebartz, A.; Ding, J.; Neumann, N. [Institut für Kernphysik, Technische Universität Darmstadt, Schloßgartenstrasse 9, D-64289 Darmstadt (Germany); Astbury, S.; Carroll, D. C.; Scott, G. G. [Central Laser Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom); Higginson, A.; McKenna, P. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Wagner, F. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Roth, M. [Institut für Kernphysik, Technische Universität Darmstadt, Schloßgartenstraße 9, D-64289 Darmstadt (Germany)

2016-08-15

We report on the experimental characterisation of laser-driven ion beams using a Thomson Parabola Spectrometer (TPS) equipped with trapezoidally shaped electric plates, proposed by Gwynne et al. [Rev. Sci. Instrum. 85, 033304 (2014)]. While a pair of extended (30 cm long) electric plates was able to produce a significant increase in the separation between neighbouring ion species at high energies, deploying a trapezoidal design circumvented the spectral clipping at the low energy end of the ion spectra. The shape of the electric plate was chosen carefully considering, for the given spectrometer configuration, the range of detectable ion energies and species. Analytical tracing of the ion parabolas matches closely with the experimental data, which suggests a minimal effect of fringe fields on the escaping ions close to the wedged edge of the electrode. The analytical formulae were derived considering the relativistic correction required for the high energy ions to be characterised using such spectrometer.

High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams

Science.gov (United States)

Alejo, A.; Kar, S.; Tebartz, A.; Ahmed, H.; Astbury, S.; Carroll, D. C.; Ding, J.; Doria, D.; Higginson, A.; McKenna, P.; Neumann, N.; Scott, G. G.; Wagner, F.; Roth, M.; Borghesi, M.

2016-08-01

We report on the experimental characterisation of laser-driven ion beams using a Thomson Parabola Spectrometer (TPS) equipped with trapezoidally shaped electric plates, proposed by Gwynne et al. [Rev. Sci. Instrum. 85, 033304 (2014)]. While a pair of extended (30 cm long) electric plates was able to produce a significant increase in the separation between neighbouring ion species at high energies, deploying a trapezoidal design circumvented the spectral clipping at the low energy end of the ion spectra. The shape of the electric plate was chosen carefully considering, for the given spectrometer configuration, the range of detectable ion energies and species. Analytical tracing of the ion parabolas matches closely with the experimental data, which suggests a minimal effect of fringe fields on the escaping ions close to the wedged edge of the electrode. The analytical formulae were derived considering the relativistic correction required for the high energy ions to be characterised using such spectrometer.

Experiments with highly-charged heavy-ions performed at the storage ring ESR

International Nuclear Information System (INIS)

Mokler, P.H.

1992-01-01

The new heavy ion accelerator facility SIS/ESR was inaugurated in April 1990. During 1991 the experimental storage ring, ESR, has been commissioned. Highly-charged heavy ions from O 8+ up to Bi 82+ were successfully accumulated, cooled, and stored in the ring. Now all highly-charged, heavy ions can be provided for experiments at comfortable storage times and at energies roughly between 100 and 500 MeV/u. A report on the achievements and on the first experimental results will be given. For the experiments, special emphasis is put on capture processes in the electron cooler, i.e. on radiative and dielectronic recombination processes as well as on capture events of bound target electrons from a gas jet. In this case, the capture leads either directly (REC) or by cascading to X-ray emission, which is also exploited for a precision spectroscopy of the structure of the heaviest ions. Another exciting topic is the radioactive decay of highly charged ions: For instance the β-decay into bound atomic states, which is not possible for neutral atoms, was studied for stored naked Dy ions. (orig.)

Electronically excited negative ion resonant states in chloroethylenes

Energy Technology Data Exchange (ETDEWEB)

Khvostenko, O.G., E-mail: khv@mail.ru; Lukin, V.G.; Tuimedov, G.M.; Khatymova, L.Z.; Kinzyabulatov, R.R.; Tseplin, E.E.

2015-02-15

Highlights: • Several novel dissociative negative ion channels were revealed in chloroethylenes. • The electronically excited resonant states were recorded in all chloroethylenes under study. • The states were assigned to the inter-shell types, but not to the core-excited Feshbach one. - Abstract: The negative ion mass spectra of the resonant electron capture by molecules of 1,1-dichloroethylene, 1,2-dichloroethylene-cis, 1,2-dichloroethylene-trans, trichloroethylene and tetrachloroethylene have been recorded in the 0–12 eV range of the captured electron energy using static magnetic sector mass spectrometer modified for operation in the resonant electron capture regime. As a result, several novel low-intensive dissociation channels were revealed in the compounds under study. Additionally, the negative ion resonant states were recorded at approximately 3–12 eV, mostly for the first time. These resonant states were assigned to the electronically excited resonances of the inter-shell type by comparing their energies with those of the parent neutral molecules triplet and singlet electronically excited states known from the energy-loss spectra obtained by previous studies.

Potential of dynamically harmonized Fourier transform ion cyclotron resonance cell for high-throughput metabolomics fingerprinting: control of data quality.

Science.gov (United States)

Habchi, Baninia; Alves, Sandra; Jouan-Rimbaud Bouveresse, Delphine; Appenzeller, Brice; Paris, Alain; Rutledge, Douglas N; Rathahao-Paris, Estelle

2018-01-01

Due to the presence of pollutants in the environment and food, the assessment of human exposure is required. This necessitates high-throughput approaches enabling large-scale analysis and, as a consequence, the use of high-performance analytical instruments to obtain highly informative metabolomic profiles. In this study, direct introduction mass spectrometry (DIMS) was performed using a Fourier transform ion cyclotron resonance (FT-ICR) instrument equipped with a dynamically harmonized cell. Data quality was evaluated based on mass resolving power (RP), mass measurement accuracy, and ion intensity drifts from the repeated injections of quality control sample (QC) along the analytical process. The large DIMS data size entails the use of bioinformatic tools for the automatic selection of common ions found in all QC injections and for robustness assessment and correction of eventual technical drifts. RP values greater than 10 6 and mass measurement accuracy of lower than 1 ppm were obtained using broadband mode resulting in the detection of isotopic fine structure. Hence, a very accurate relative isotopic mass defect (RΔm) value was calculated. This reduces significantly the number of elemental composition (EC) candidates and greatly improves compound annotation. A very satisfactory estimate of repeatability of both peak intensity and mass measurement was demonstrated. Although, a non negligible ion intensity drift was observed for negative ion mode data, a normalization procedure was easily applied to correct this phenomenon. This study illustrates the performance and robustness of the dynamically harmonized FT-ICR cell to perform large-scale high-throughput metabolomic analyses in routine conditions. Graphical abstract Analytical performance of FT-ICR instrument equipped with a dynamically harmonized cell.

Electron capture and energy-gain spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Taulbjerg, K.

1989-01-01

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

Salmonella capture using orbiting magnetic microbeads

Science.gov (United States)

Owen, Drew; Ballard, Matthew; Mills, Zachary; Hanasoge, Srinivas; Hesketh, Peter; Alexeev, Alexander

2014-11-01

Using three-dimensional simulations and experiments, we examine capture of salmonella from a complex fluid sample flowing through a microfluidic channel. Capture is performed using orbiting magnetic microbeads, which can easily be extracted from the system for analysis after salmonella capture. Numerical simulations are used to model the dynamics of the system, which consists of a microchannel filled with a viscous fluid, model salmonella, magnetic microbeads and a series of angled parallel ridges lining the top of the microchannel. Simulations provide a statistical measure of the ability of the system to capture target salmonella. Our modeling findings guide the design of a lab-on-a-chip experimental device to be used for the detection of salmonella from complex food samples, allowing for the detection of the bacteria at the food source and preventing the consumption of contaminated food. Such a device can be used as a generic platform for the detection of a variety of biomaterials from complex fluids. This work is supported by a grant from the United States Department of Agriculture.

Sensitivity of ion-induced sputtering to the radial distribution of energy transfers: A molecular dynamics study

International Nuclear Information System (INIS)

Mookerjee, S.; Khan, S. A.; Roy, A.; Beuve, M.; Toulemonde, M.

2008-01-01

Using different models for the deposition of energy on the lattice and a classical molecular dynamics approach to the subsequent transport, we evaluate how the details of the energy deposition model influence sputtering yield from a Lennard-Jones target irradiated with a MeV/u ion beam. Two energy deposition models are considered: a uniform, instantaneous deposition into a cylinder of fixed radius around the projectile ion track, used in earlier molecular dynamics and fluid dynamics simulations of sputtering yields; and an energy deposition distributed in time and space based on the formalism developed in the thermal spike model. The dependence of the sputtering yield on the total energy deposited on the target atoms is very sensitive to the energy deposition model. To clarify the origin of this strong dependence, we explore the role of the radial expansion of the electronic system prior to the transfer of its energy to the lattice. The results imply that observables such as the sputtering yield may be used as signatures of the fast electron-lattice energy transfer in the electronic energy-loss regime, and indicate the need for more experimental and theoretical investigations of these processes

Entirely irrelevant distractors can capture and captivate attention

OpenAIRE

Forster, Sophie; Lavie, Nilli

2011-01-01

The question of whether a stimulus onset may capture attention when it is entirely irrelevant to the task and even in the absence of any attentional settings for abrupt onset or any dynamic changes has been highly controversial. In the present study, we designed a novel irrelevant capture task to address this question. Participants engaged in a continuous task making sequential forced choice (letter or digit) responses to each item in an alphanumeric matrix that remained on screen throughout ...

Assessing the ability of potential evapotranspiration models in capturing dynamics of evaporative demand across various biomes and climatic regimes with ChinaFLUX measurements

Science.gov (United States)

Zheng, Han; Yu, Guirui; Wang, Qiufeng; Zhu, Xianjin; Yan, Junhua; Wang, Huimin; Shi, Peili; Zhao, Fenghua; Li, Yingnian; Zhao, Liang; Zhang, Junhui; Wang, Yanfen

2017-08-01

Estimates of atmospheric evaporative demand have been widely required for a variety of hydrological analyses, with potential evapotranspiration (PET) being an important measure representing evaporative demand of actual vegetated surfaces under given metrological conditions. In this study, we assessed the ability of various PET models in capturing long-term (typically 2003-2011) dynamics of evaporative demand at eight ecosystems across various biomes and climatic regimes in China. Prior to assessing PET dynamics, we first examined the reasonability of fourteen PET models in representing the magnitudes of evaporative demand using eddy-covariance actual evapotranspiration (AET) as an indicator. Results showed that the robustness of the fourteen PET models differed somewhat across the sites, and only three PET models could produce reasonable magnitudes of evaporative demand (i.e., PET ≥ AET on average) for all eight sites, including the: (i) Penman; (ii) Priestly-Taylor and (iii) Linacre models. Then, we assessed the ability of these three PET models in capturing dynamics of evaporative demand by comparing the annual and seasonal trends in PET against the equivalent trends in AET and precipitation (P) for particular sites. Results indicated that nearly all the three PET models could faithfully reproduce the dynamics in evaporative demand for the energy-limited conditions at both annual and seasonal scales, while only the Penman and Linacre models could represent dynamics in evaporative demand for the water-limited conditions. However, the Linacre model was unable to reproduce the seasonal switches between water- and energy-limited states for some sites. Our findings demonstrated that the choice of PET models would be essential for the evaporative demand analyses and other related hydrological analyses at different temporal and spatial scales.

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

CERN Multimedia

2002-01-01

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

Ion distribution dynamics near the Earth's bow shock: first measurements with the 2D ion energy spectrometer CORALL on the INTERBALL/Tail-probe satellite

Directory of Open Access Journals (Sweden)

Yu. I. Yermolaev

1997-05-01

Full Text Available The dynamics of the ion distribution function near the Earth's bow shock is studied on the basis of quasi-3D measurements of ion energy spectra in the range of 30–24200 eV/q with the Russian-Cuban CORALL instrument on the INTERBALL/Tail-probe satellite. The instrument was designed for observations of magnetospheric plasma and measures ions, in an angular range of 36°–144° from the Earth-Sun direction. Ion populations generated by the Earth bow shock are often observed upstream from the bow shock. In the solar-wind stream compressed and heated by the passing of very dense magnetic cloud (CME, two types of these ion populations were measured upstream and before the bow shock crossing on 25 August 1995 at 07:37 UT. Both populations were observed in the energy range above 2 keV. At ~06:20 UT, when the angle between the direction of the interplanetary magnetic field and normal to the bow shock VBn was ≃ 43° the instrument observed a narrow, fast (~800 km/s field-aligned beam moving from the Earth. At ~07:30, when Bn ≃ 28°, the wide ion pitch-angle distribution was observed. A similar suprathermal ion population is observed in the magnetosheath simultaneously with the solar-wind ion population being heated and deflected from the Sun-Earth direction. The similarity of observations during the mentioned time-interval and under usual solar-wind conditions allows us to conclude that types of suprathermal ion populations upstream and downstream from the bow shock do not depend on the solar-wind disturbance generated by magnetic cloud.

Ion-ion interaction and energy transfer of 4+ transuranium ions in cerium tetrafluoride

International Nuclear Information System (INIS)

Liu, G.K.; Beitz, J.V.

1990-01-01

Dynamics of excited 5f electron states of the transuranium ions Cm 4+ and Bk 4+ in CeF 4 are compared. Based on time- and wavelength-resolved laser-induced fluorescence, excitation energy transfer processes have been probed. Depending on concentration and electronic energy level structure of the studied 4+ transuranium ion, the dominant energy transfer mechanisms were identified as cross relaxation, exciton-exciton annihilation, and trapping. Energy transfer rates derived from the fitting of the observed fluorescence decays to theoretical models, based on electric multipolar ion-ion interactions, are contrasted with prior studies of 4f states of 3+ lanthanide and 3d states of transition metal ions. 16 refs., 1 tab

Audiovisual Capture with Ambiguous Audiovisual Stimuli

Directory of Open Access Journals (Sweden)

Jean-Michel Hupé

2011-10-01

Full Text Available Audiovisual capture happens when information across modalities get fused into a coherent percept. Ambiguous multi-modal stimuli have the potential to be powerful tools to observe such effects. We used such stimuli made of temporally synchronized and spatially co-localized visual flashes and auditory tones. The flashes produced bistable apparent motion and the tones produced ambiguous streaming. We measured strong interferences between perceptual decisions in each modality, a case of audiovisual capture. However, does this mean that audiovisual capture occurs before bistable decision? We argue that this is not the case, as the interference had a slow temporal dynamics and was modulated by audiovisual congruence, suggestive of high-level factors such as attention or intention. We propose a framework to integrate bistability and audiovisual capture, which distinguishes between “what” competes and “how” it competes (Hupé et al., 2008. The audiovisual interactions may be the result of contextual influences on neural representations (“what” competes, quite independent from the causal mechanisms of perceptual switches (“how” it competes. This framework predicts that audiovisual capture can bias bistability especially if modalities are congruent (Sato et al., 2007, but that is fundamentally distinct in nature from the bistable competition mechanism.

Atomic physics at the Argonne PII ECR [electron cyclotron resonance] Ion Source

International Nuclear Information System (INIS)

Dunford, R.W.; Berry, H.G.; Billquist, P.J.; Pardo, R.C.; Zabransky, B.J.; Bakke, E.; Groeneveld, K.O.; Hass, M.; Raphaelian, M.L.A.

1987-01-01

An atomic physics beam line has been set up at the Argonne PII ECR Ion Source. The source is on a 350-kV high-voltage platform which is a unique feature of particular interest in work on atomic collisions. We describe our planned experimental program which includes: measurement of state-selective electron-capture cross sections, studies of doubly-excited states, precision spectroscopy of few-electron ions, tests of quantum electrodynamics, and studies of polarization transfer using optically pumped polarized alkali targets. The first experiments will be measurements of cross sections for electron capture into specific nl subshells in ion-atom collisions. Our method is to observe the characteristic radiation emitted after capture using a VUV spectrometer. Initial data from these experiments are presented. 12 refs., 4 figs

Microstructure of titanium oxide films synthesized by ion beam dynamic mixing

International Nuclear Information System (INIS)

Makino, Y.; Setsuhara, Y.; Miyake, S.

1994-01-01

The microstructure of titanium oxide films synthesized by the ion beam dynamic mixing (IBDM) method is investigated by glancing angle X-ray diffraction and multi-reflectance FT-IR methods. Titanium oxide films are identified as rutile phases having different degrees of (110) orientation. The IBDM rutile phase with a standard crystalline state is produced by controlling the ratio of the intensities between the (110) and (101) peaks of the rutile, I(110)/I(101), so as to approach the ratio to the value (=2.0) of ASTM standard rutile. The crystallite size of the rutile phase increases with increasing ratio of intensities of the two XRD peaks, I(110)/I(101). The increase of the crystallite size is suggested to be attributed to the increase of oxygen ion energy per Ti atom. From the dependence of the IR absorption near 500 cm -1 upon I(110)/I(101), it is indicated that the Ti-O bond strength is delicately affected by the degree of (110) orientation of the IBDM rultile phase. ((orig.))

Recent measurements of low energy charge exchange cross sections for collisions of multicharged ions on neutral atoms and molecules

International Nuclear Information System (INIS)

Havener, Charles C.

2001-01-01

At ORNL Multicharged Ion Research Facility (MIRF), charge exchange (CX) cross sections have been measured for multicharged ions (MCI) on neutral atoms and molecules. The ORNL ion-atom merged-beam apparatus was used to measure single electron capture by MCI from H at eV/amu energies. A gas cell was used to measure single and double electron capture by MCI from a variety of molecular targets at keV collision energies. The merged-beams experiment has been successful in providing benchmark total electron capture measurements for several collision systems with a variety of multicharged ions on H or D

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

NARCIS (Netherlands)

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

2008-01-01

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

Ion Dynamics in a Mixed-Cation Alkoxy-Ammonium Ionic Liquid Electrolyte for Sodium Device Applications.

Science.gov (United States)

Pope, Cameron R; Kar, Mega; MacFarlane, Douglas R; Armand, Michel; Forsyth, Maria; O'Dell, Luke A

2016-10-18

The ion dynamics in a novel sodium-containing room-temperature ionic liquid (IL) consisting of an ether-functionalised quaternary ammonium cation and bis(trifluoromethylsulfonyl)amide [NTf 2 ] anion with various concentrations of Na[NTf 2 ] have been characterised using differential scanning calorimetry, impedance spectroscopy, diffusometry and NMR relaxation measurements. The IL studied has been specifically designed to dissolve a relatively large concentration of Na[NTf 2 ] salt (over 2 mol kg -1 ) as this has been shown to improve ion transport and conductivity. Consistent with other studies, the measured ionic conductivity and diffusion coefficients show that the overall ionic mobility decreases with decreasing temperature and increasing salt content. NMR relaxation measurements provide evidence for correlated dynamics between the ether-functionalised ammonium and Na cations, possibly with the latter species acting as cross-links between multiple ammonium cations. Finally, preliminary cyclic voltammetry experiments show that this IL can undergo stable electrochemical cycling and could therefore be potentially useful as an electrolyte in a Na-based device. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of ion-neutral chemical reactions on dynamics of lightning-induced electric field

International Nuclear Information System (INIS)

Hiraki, Yasutaka

2009-01-01

Secondary lightning phenomena in the upper atmosphere called sprites attract interest from the viewpoint of atomic-molecular and plasma physics. Lightning-induced electric field accelerates the ionospheric electrons up to tens of electron-volts, inducing electrical breakdown as well as strong optical emissions, through electron impact ionization of molecules. A large-scale structure of sprites is constructed by collective dynamics of filamentary streamer discharges in a rarified gas, which in turn is controlled by the distribution of the background electric field. In this paper, we firstly reanalyze the relationship between quasi-static field formation and local ion chemistry with first-order perturbation techniques. Secondly, we investigate with a full ion chemical model the effects of electron attachment to oxygen molecules on its density in moderate cases of undervoltage lightning electric fields rather than the cases of intense ionization in streamers. We estimate the minimum values that are provided by the chemical balance with electron detachment from negative ions. We also investigate the recovery timescale of the electron density and find that the scale (≥1 s) is occasionally much larger than the interval of each lightning stroke (∼10 ms). We suggest that the subsequent sprite event as well as the field formation could be well affected by the ghost of the primary event. We discuss further the negative ion chemistry triggered by electron attachment in the nighttime mesosphere.

The dynamics of a neoclassical tearing mode (NTM) influenced by energetic ions on EAST

International Nuclear Information System (INIS)

Li, Erzhong; Xu, L; Shi, T; Zhao, H; Liu, Y; Ti, A; Zhang, J; Huang, J; Shen, B; Lin, S; Qian, J; Gong, X; Hu, L; Igochine, V; White, R; Zhu, Y

2016-01-01

In the 2014 year’s campaign of experimental advanced superconducting tokamak (EAST), a series of Magnetohydrodynamics (MHD) instabilities were observed as the launching of Neutral Beam Injection (NBI), the most interesting one of which is the neoclassical tearing mode (NTM). Evidence clearly shows that a kink mode present after a strong sawtooth-like (ST-like) crash leaves a perturbation near the location of the magnetic island, providing the initial seed. The interaction of energetic ions makes the magnetic island oscillate both in island width and in rotation frequency. Analysis indicates that the bulk plasma still dominates the dynamics of NTM, and the orbit excursion of energetic ions induces a polarization current and modifies the width and rotation frequency of the neoclassical magnetic island. (paper)

Molecular dynamics simulations to examine structure, energetics, and evaporation/condensation dynamics in small charged clusters of water or methanol containing a single monatomic ion.

Science.gov (United States)

Daub, Christopher D; Cann, Natalie M

2012-11-01

We study small clusters of water or methanol containing a single Ca(2+), Na(+), or Cl(-) ion with classical molecular dynamics simulations, using models that incorporate polarizability via the Drude oscillator framework. Evaporation and condensation of solvent from these clusters is examined in two systems, (1) for isolated clusters initially prepared at different temperatures and (2) those with a surrounding inert (Ar) gas of varying temperature. We examine these clusters over a range of sizes, from almost bare ions up to 40 solvent molecules. We report data on the evaporation and condensation of solvent from the clusters and argue that the observed temperature dependence of evaporation in the smallest clusters demonstrates that the presence of heated gas alone cannot, in most cases, solely account for bare ion production in electrospray ionization (ESI), neglecting the key contribution of the electric field. We also present our findings on the structure and energetics of the clusters as a function of size. Our data agree well with the abundant literature on hydrated ion clusters and offer some novel insight into the structure of methanol and ion clusters, especially those with a Cl(-) anion, where we observe the presence of chain-like structures of methanol molecules. Finally, we provide some data on the reparameterizations necessary to simulate ions in methanol using the separately developed Drude oscillator models for methanol and for ions in water.

Dynamic SIMS utilizing SF{sub 5}{sup +} polyatomic primary ion beams for drug delivery applications

Energy Technology Data Exchange (ETDEWEB)

Mahoney, Christine M.; Roberson, Sonya; Gillen, Greg

2004-06-15

The behavior of various biodegradable polymer films (e.g. polylactic acid, polyglycolic acid and polycaprolactone) as well as some model drugs (theophylline and 4-acetamidophenol) under dynamic SF{sub 5}{sup +} primary ion bombardment is explored. A series of polylactic acid films containing varying concentrations of 4-acetamidophenol are also analyzed under similar conditions. The resultant molecular depth profiles obtained from these polymer films doped with drug show very little degradation in molecular signal as a function of SF{sub 5}{sup +} primary ion dose, and it was found that the molecular ion signals of both polymer and drug remained constant for ion doses up to {approx}5x10{sup 15} ions/cm{sup 2}. In addition, the polymer film/Si interface was well defined which may imply that sputter-induced topography formation was not a significant limitation. These results suggest that the structure of the biodegradable polymers studied here which all have the common main chain structural unit, R-CO-O-R, allows for a greater ability to depth profile due to ease of bond cleavage. Most importantly, however, these results indicate that in these particular polymer systems, the distribution of the drug as a function of depth can be monitored.

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

International Nuclear Information System (INIS)

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

1985-01-01

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

Peri-dynamics

International Nuclear Information System (INIS)

Littlewood, D.

2015-01-01