WorldWideScience

Sample records for partial ionization cross

  1. Ionization of xenon by electrons: Partial cross sections for single, double, and triple ionization

    International Nuclear Information System (INIS)

    Mathur, D.; Badrinathan, C.

    1987-01-01

    High-sensitivity measurements of relative partial cross sections for single, double, and triple ionization of Xe by electron impact have been carried out in the energy region from threshold to 100 eV using a crossed-beam apparatus incorporating a quadrupole mass spectrometer. The weighted sum of the relative partial cross sections at 50 eV are normalized to the total ionization cross section of Rapp and Englander-Golden to yield absolute cross-section functions. Shapes of the partial cross sections for single and double ionization are difficult to account for within a single-particle picture. Comparison of the Xe + data with 4d partial photoionization cross-section measurements indicates the important role played by many-body effects in describing electron-impact ionization of high-Z atoms

  2. Total, partial and differential ionization cross sections in proton-hydrogen collisions at low energy

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Shiyang [Graduate University for Advanced Studies, School of Mathematical and Physical Science, Toki, Gifu (Japan); Pichl, Lukas [University of Aizu, Foundation of Computer Science Laboratory, Aizuwakamatsu, Fukushima (Japan); Kimura, Mineo [Yamaguchi Univ., Graduate School of Science and Engineering, Ube, Yamaguchi (Japan); Kato, Takako [National Inst. for Fusion Science, Toki, Gifu (Japan)

    2003-01-01

    Single-differential, partial and total ionization cross sections for the proton-hydrogen collision system at low energy range (0.1-10 keV/amu) are determined by using the electron translation factor corrected molecular-orbital close-coupling method. Full convergence of ionization cross sections as a function of H{sub 2}{sup +} molecular basis size is achieved by including up to 10 bound states, and 11 continuum partial waves. The present cross sections are in an excellent agreement with the recent experiments of Shah et al., but decrease more rapidly than the cross sections measured by Pieksma et al. with decreasing energy. The calculated cross section data are included in this report. (author)

  3. Physics of partially ionized plasmas

    CERN Document Server

    Krishan, Vinod

    2016-01-01

    Plasma is one of the four fundamental states of matter; the other three being solid, liquid and gas. Several components, such as molecular clouds, diffuse interstellar gas, the solar atmosphere, the Earth's ionosphere and laboratory plasmas, including fusion plasmas, constitute the partially ionized plasmas. This book discusses different aspects of partially ionized plasmas including multi-fluid description, equilibrium and types of waves. The discussion goes on to cover the reionization phase of the universe, along with a brief description of high discharge plasmas, tokomak plasmas and laser plasmas. Various elastic and inelastic collisions amongst the three particle species are also presented. In addition, the author demonstrates the novelty of partially ionized plasmas using many examples; for instance, in partially ionized plasma the magnetic induction is subjected to the ambipolar diffusion and the Hall effect, as well as the usual resistive dissipation. Also included is an observation of kinematic dynam...

  4. Mass spectrometric determination of partial electron impact ionization cross sections of No, No2, and N2O from threshold up to 180 eV

    International Nuclear Information System (INIS)

    Kim, Y. B.

    1982-01-01

    Electron impact ionization of nitric oxide (NO), nitrogen dioxide (NO 2 ) and nitrous oxide (N 2 O) has been studied as a function of electron energy up to 180 eV with a double focussing mass spectrometer Varian MAT CH5 and an improved Nier type electron impact ion source. Relative partial ionization cross sections were measured for the processes NO + + 2e, NO ++ + 3e, and NO 2 + e -> NO + 2 + 2e, NO ++ + 3e and N 2 O + e -> N 2 O + + 2e. An accurate measurement of the cross section ratios q(NO 2+ /NO)/q(NO + /NO) and q(NO 2 2 /NO 2 )/q(NO + 2 /NO 2 ) has been made. Relative cross section functions were calibrated absolutely with two different normalization methods. Moreover, both metastable and collision induced dissociations of N 2 O + were studied quantitatively using the technique of decoupling the acceleration and deflection electric fields. Using the n- th root extrapolation the following ionization potentials have been derived from the cross section functions near threshold: NO + (X 1 Σ + ); NO ++ ; NO + 2 ; NO 2 ++ ; N 2 O + (X 2 π). These results are compared with previous measurements and theoretical calculations, where available. Part of the results presented have been already published in seven papers by the author. (Author)

  5. Neutral Atom Diffusion in a Partially Ionized Prominence Plasma

    Science.gov (United States)

    Gilbert, Holly

    2010-01-01

    The support of solar prominences is normally described in terms of a magnetic force on the prominence plasma that balances the solar gravitational force. Because the prominence plasma is only partially ionized. it is necessary to consider in addition the support of the neutral component of the prominence plasma. This support is accomplished through a frictional interaction between the neutral and ionized components of the plasma, and its efficacy depends strongly on the degree of ionization of the plasma. More specifically, the frictional force is proportional to the relative flow of neutral and ion species, and for a sufficiently weakly ionized plasma, this flow must be relatively large to produce a frictional force that balances gravity. A large relative flow, of course, implies significant draining of neutral particles from the prominence. We evaluate the importance of this draining effect for a hydrogen-helium plasma, and consider the observational evidence for cross-field diffusion of neutral prominence material,

  6. Absolute partial photoionization cross sections of ethylene

    Science.gov (United States)

    Grimm, F. A.; Whitley, T. A.; Keller, P. R.; Taylor, J. W.

    1991-07-01

    Absolute partial photoionization cross sections for ionization out of the first four valence orbitals to the X 2B 3u, A 2B 3g, B 2A g and C 2B 2u states of the C 2H 4+ ion are presented as a function of photon energy over the energy range from 12 to 26 eV. The experimental results have been compared to previously published relative partial cross sections for the first two bands at 18, 21 and 24 eV. Comparison of the experimental data with continuum multiple scattering Xα calculations provides evidence for extensive autoionization to the X 2B 3u state and confirms the predicted shape resonances in ionization to the A 2B 3g and B 2A g states. Identification of possible transitions for the autoionizing resonances have been made using multiple scattering transition state calculations on Rydberg excited states.

  7. Theory on a partially ionized gas centrifuge

    International Nuclear Information System (INIS)

    Berg, M.S. van den.

    1982-01-01

    This thesis contains a study of some flow processes occurring in the Gaswhirl experiments. In this apparatus a partially ionized gas is forced into rotation by an azimuthal electromagnetic force. After a short introduction in which a motivation is given of our research project, a comprehensive treatment is presented of the principle of rotating plasmas. Further, a historical review is given of rotating plasma systems. A derivation of the fundamental equations is given which describe the flow system mathematically and these are applied to rotating plasmas. The occurrence of secondary flows with radial and axial components is considered. This qualitative picture of secondary whirls is confirmed by measurements reported in the next chapter. The last chapter offers a possible explanation of the occurrence of the transition process in the Gaswhirl apparatus. (Auth.)

  8. MICROWAVE INTERACTIONS WITH INHOMOGENEOUS PARTIALLY IONIZED PLASMA

    Energy Technology Data Exchange (ETDEWEB)

    Kritz, A. H.

    1962-11-15

    Microwave interactions with inhomogeneous plasmas are often studied by employing a simplified electromagnetic approach, i.e., by representing the effects of the plasma by an effective dielectric coefficient. The problems and approximations associated with this procedure are discussed. The equation describing the microwave field in an inhomogeneous partially ionized plasma is derived, and the method that is applied to obtain the reflected, transmitted, and absorbed intensities in inhomogeneous plasmas is presented. The interactions of microwaves with plasmas having Gaussian electron density profiles are considered. The variation of collision frequency with position is usually neglected. In general, the assumption of constant collision frequency is not justified; e.g., for a highly ionized plasma, the electron density profile determines, in part, the profile of the electron-ion collision frequency. The effect of the variation of the collision frequency profile on the interaction of microwaves with inhomogeneous plasmas is studied in order to obtain an estimate of the degree of error that may result when constant collision frequency is assumed instead of a more realistic collision frequency profile. It is shown that the degree of error is of particular importance when microwave analysis is used as a plasma diagnostic. (auth)

  9. Heating and ionization in MHD shock waves propagating into partially ionized plasma

    International Nuclear Information System (INIS)

    Bighel, L.; Collins, A.R.; Cramer, N.F.; Watson-Munro, C.N.

    1975-09-01

    A model of the structure of MHD switch-on shocks propagating in a partially ionized plasma, in which the primary dissipation mechanism is friction between ions and neutrals, is here compared favourably with experimental results. Four degrees of upstream ionization were studied, ranging from almost complete to very small ionization. (author)

  10. Heating and ionization in MHD shock wave propagating into partially ionized plasma

    International Nuclear Information System (INIS)

    Bighel, L.; Collins, A.R.; Cramer, N.F.; Watson-Munro, C.N.

    1975-09-01

    A model of the structure of MHD switch-on shocks propagating in a partially ionized plasma, in which the primary dissipation mechanism is friction between ions and neutrals, is here compared favourably with experimental results. Four degrees of upstream ionization were studied, ranging from almost complete to very small ionization. (author)

  11. Tachyonic ionization cross sections of hydrogenic systems

    Energy Technology Data Exchange (ETDEWEB)

    Tomaschitz, Roman [Department of Physics, Hiroshima University, 1-3-1 Kagami-yama, Higashi-Hiroshima 739-8526 (Japan)

    2005-03-11

    Transition rates for induced and spontaneous tachyon radiation in hydrogenic systems as well as the transversal and longitudinal ionization cross sections are derived. We investigate the interaction of the superluminal radiation field with matter in atomic bound-bound and bound-free transitions. Estimates are given for Ly-{alpha} transitions effected by superluminal quanta in hydrogen-like ions. The tachyonic photoelectric effect is scrutinized, in the Born approximation and at the ionization threshold. The angular maxima occur at different scattering angles in the transversal and longitudinal cross sections, which can be used to sift out longitudinal tachyonic quanta in a photon flux. We calculate the tachyonic ionization and recombination cross sections for Rydberg states and study their asymptotic scaling with respect to the principal quantum number. At the ionization threshold of highly excited states of order n {approx} 10{sup 4}, the longitudinal cross section starts to compete with photoionization, in recombination even at lower levels.

  12. The multiple ionization of helium induced by partially stripped carbon ions

    International Nuclear Information System (INIS)

    Cai Xiaohong; Chen Ximeng; Shen Ziyong

    1996-01-01

    The ratios of the double to single ionization cross sections of helium impacted by partially stripped C q+ ions (q = 1,2,3,4) in energy range of 1.5-7.5 MeV were measured by using the time of flight procedure. The n-body classical trajectory Monte Carlo calculation was carried out to get the Olson-Schlachter scaling. The single and double ionization cross sections of helium were obtained by comparing the cross section ratios of the present work with the Olson-Schlachter scaling

  13. ALFVEN WAVES IN A PARTIALLY IONIZED TWO-FLUID PLASMA

    Energy Technology Data Exchange (ETDEWEB)

    Soler, R.; Ballester, J. L.; Terradas, J. [Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Carbonell, M., E-mail: roberto.soler@uib.es, E-mail: joseluis.ballester@uib.es, E-mail: jaume.terradas@uib.es, E-mail: marc.carbonell@uib.es [Departament de Matematiques i Informatica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)

    2013-04-20

    Alfven waves are a particular class of magnetohydrodynamic waves relevant in many astrophysical and laboratory plasmas. In partially ionized plasmas the dynamics of Alfven waves is affected by the interaction between ionized and neutral species. Here we study Alfven waves in a partially ionized plasma from the theoretical point of view using the two-fluid description. We consider that the plasma is composed of an ion-electron fluid and a neutral fluid, which interact by means of particle collisions. To keep our investigation as general as possible, we take the neutral-ion collision frequency and the ionization degree as free parameters. First, we perform a normal mode analysis. We find the modification due to neutral-ion collisions of the wave frequencies and study the temporal and spatial attenuation of the waves. In addition, we discuss the presence of cutoff values of the wavelength that constrain the existence of oscillatory standing waves in weakly ionized plasmas. Later, we go beyond the normal mode approach and solve the initial-value problem in order to study the time-dependent evolution of the wave perturbations in the two fluids. An application to Alfven waves in the low solar atmospheric plasma is performed and the implication of partial ionization for the energy flux is discussed.

  14. MAGNETOACOUSTIC WAVES IN A PARTIALLY IONIZED TWO-FLUID PLASMA

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Roberto; Ballester, Jose Luis [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Carbonell, Marc, E-mail: roberto.soler@uib.es, E-mail: joseluis.ballester@uib.es, E-mail: marc.carbonell@uib.es [Departament de Matemàtiques i Informàtica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)

    2013-11-01

    Compressible disturbances propagate in a plasma in the form of magnetoacoustic waves driven by both gas pressure and magnetic forces. In partially ionized plasmas the dynamics of ionized and neutral species are coupled due to ion-neutral collisions. As a consequence, magnetoacoustic waves propagating through a partially ionized medium are affected by ion-neutral coupling. The degree to which the behavior of the classic waves is modified depends on the physical properties of the various species and on the relative value of the wave frequency compared to the ion-neutral collision frequency. Here, we perform a comprehensive theoretical investigation of magnetoacoustic wave propagation in a partially ionized plasma using the two-fluid formalism. We consider an extensive range of values for the collision frequency, ionization ratio, and plasma β, so that the results are applicable to a wide variety of astrophysical plasmas. We determine the modification of the wave frequencies and study the frictional damping due to ion-neutral collisions. Approximate analytic expressions for the frequencies are given in the limit case of strongly coupled ions and neutrals, while numerically obtained dispersion diagrams are provided for arbitrary collision frequencies. In addition, we discuss the presence of cutoffs in the dispersion diagrams that constrain wave propagation for certain combinations of parameters. A specific application to propagation of compressible waves in the solar chromosphere is given.

  15. MAGNETOACOUSTIC WAVES IN A PARTIALLY IONIZED TWO-FLUID PLASMA

    International Nuclear Information System (INIS)

    Soler, Roberto; Ballester, Jose Luis; Carbonell, Marc

    2013-01-01

    Compressible disturbances propagate in a plasma in the form of magnetoacoustic waves driven by both gas pressure and magnetic forces. In partially ionized plasmas the dynamics of ionized and neutral species are coupled due to ion-neutral collisions. As a consequence, magnetoacoustic waves propagating through a partially ionized medium are affected by ion-neutral coupling. The degree to which the behavior of the classic waves is modified depends on the physical properties of the various species and on the relative value of the wave frequency compared to the ion-neutral collision frequency. Here, we perform a comprehensive theoretical investigation of magnetoacoustic wave propagation in a partially ionized plasma using the two-fluid formalism. We consider an extensive range of values for the collision frequency, ionization ratio, and plasma β, so that the results are applicable to a wide variety of astrophysical plasmas. We determine the modification of the wave frequencies and study the frictional damping due to ion-neutral collisions. Approximate analytic expressions for the frequencies are given in the limit case of strongly coupled ions and neutrals, while numerically obtained dispersion diagrams are provided for arbitrary collision frequencies. In addition, we discuss the presence of cutoffs in the dispersion diagrams that constrain wave propagation for certain combinations of parameters. A specific application to propagation of compressible waves in the solar chromosphere is given

  16. Dynamic conductivity and partial ionization in dense fluid hydrogen

    Science.gov (United States)

    Zaghoo, Mohamed

    2018-04-01

    A theoretical description for optical conduction experiments in dense fluid hydrogen is presented. Different quantum statistical approaches are used to describe the mechanism of electronic transport in hydrogen's high-temperature dense phase. We show that at the onset of the metallic transition, optical conduction could be described by a strong rise in atomic polarizability, due to increased ionization, whereas in the highly degenerate limit, the Ziman weak scattering model better accounts for the observed saturation of reflectance. The inclusion of effects of partial ionization in the highly degenerate region provides great agreement with experimental results. Hydrogen's fluid metallic state is revealed to be a partially ionized free-electron plasma. Our results provide some of the first theoretical transport models that are experimentally benchmarked, as well as an important guide for future studies.

  17. Approximate thermodynamic state relations in partially ionized gas mixtures

    International Nuclear Information System (INIS)

    Ramshaw, John D.

    2004-01-01

    Thermodynamic state relations for mixtures of partially ionized nonideal gases are often approximated by artificially partitioning the mixture into compartments or subvolumes occupied by the pure partially ionized constituent gases, and requiring these subvolumes to be in temperature and pressure equilibrium. This intuitively reasonable procedure is easily shown to reproduce the correct thermal and caloric state equations for a mixture of neutral (nonionized) ideal gases. The purpose of this paper is to point out that (a) this procedure leads to incorrect state equations for a mixture of partially ionized ideal gases, whereas (b) the alternative procedure of requiring that the subvolumes all have the same temperature and free electron density reproduces the correct thermal and caloric state equations for such a mixture. These results readily generalize to the case of partially degenerate and/or relativistic electrons, to a common approximation used to represent pressure ionization effects, and to two-temperature plasmas. This suggests that equating the subvolume electron number densities or chemical potentials instead of pressures is likely to provide a more accurate approximation in nonideal plasma mixtures

  18. Turbulent Dynamics of Partially-Ionized Fluids in 2D

    Science.gov (United States)

    Benavides, S.; Flierl, G.

    2017-12-01

    Ionization occurs in the upper atmospheres of Hot Jupiters, as well asthe interiors of Gas Giants, leading to Magnetohydrodynamic (MHD) effectswhich can significantly alter the flow. The interactions of these MHDregions with the non-ionized atmosphere will occur in transitionregions where only a fraction of the fluid is ionized. We areexploring the dynamics of Partially-Ionized MHD (PIMHD) using a twofluid model - one neutral and one ionized and subject to MHD -coupled by a collision, or Joule heating, term proportional to thedifference in velocities. By varying both the ionization fraction aswell as the collision frequency (coupling), we examine the parameterspace of 2D PIMHD turbulence in hopes of better understanding itscharacteristics in certain, possibly realistic, regimes. We payparticular attention to the Joule heating term and its role indissipation and energy exchange between the two species. Thisknowledge will serve as the basis to further studies in which we lookat, in a more realistic setting, the PIMHD dynamics in Gas Giant orHot Jupiter atmospheres.

  19. MAGNETOHYDRODYNAMIC WAVES IN A PARTIALLY IONIZED FILAMENT THREAD

    International Nuclear Information System (INIS)

    Soler, R.; Oliver, R.; Ballester, J. L.

    2009-01-01

    Oscillations and propagating waves are commonly seen in high-resolution observations of filament threads, i.e., the fine-structures of solar filaments/prominences. Since the temperature of prominences is typically of the order of 10 4 K, the prominence plasma is only partially ionized. In this paper, we study the effect of neutrals on the wave propagation in a filament thread modeled as a partially ionized homogeneous magnetic flux tube embedded in an homogeneous and fully ionized coronal plasma. Ohmic and ambipolar magnetic diffusion are considered in the basic resistive magnetohydrodynamic (MHD) equations. We numerically compute the eigenfrequencies of kink, slow, and Alfven linear MHD modes and obtain analytical approximations in some cases. We find that the existence of propagating modes is constrained by the presence of critical values of the longitudinal wavenumber. In particular, the lower and upper frequency cutoffs of kink and Alfven waves owe their existence to magnetic diffusion parallel and perpendicular to magnetic field lines, respectively. The slow mode only has a lower frequency cutoff, which is caused by perpendicular magnetic diffusion and is significantly affected by the ionization degree. In addition, ion-neutral collision is the most efficient damping mechanism for short wavelengths, while ohmic diffusion dominates in the long-wavelength regime.

  20. Theory of vortex flows in partially ionized magnetoplasmas

    Energy Technology Data Exchange (ETDEWEB)

    Jovanovic, D.; Shukla, P.K

    2004-06-07

    A complete theory for vortex flows in partially ionized magnetoplasmas is presented. Accurate analytical and numerical results are obtained concerning the structure of a Burger's vortex and a tripolar vortex. A novel type of rotating tripolar vortices with elliptic cores are found in the systems dominated by the convection in incompressible flows, but whose generation is triggered by the diffusive and compressible effects. Our vortex flow models successfully explain recent observations from laboratory magnetoplasmas and geophysical flows.

  1. Turbulence effect on Ohm's law in partially ionized plasmas

    International Nuclear Information System (INIS)

    Numano, M.

    1977-01-01

    An investigation of the effect of nonuniformity on electric current flow in partially ionized plasmas is made. An Ohm's law for a nonuniform plasma was derived, from which Rosa's equation is obtained as a special case. Making use of this new Ohm's law, the effective electrical conductivity and Hall coefficient are determined for isotropically turbulent plasmas. They are found to be in good agreement with the results obtained previously. (author)

  2. Equation of state of partially-ionized dense plasmas

    International Nuclear Information System (INIS)

    Rogers, F.J.

    1989-01-01

    This paper describes methods for calculating the equation of state of partially-ionized dense plasmas. The term dense plasma is used rather than strongly coupled plasma, since it is possible that at plasma conditions such that only a few levels can be observed spectroscopically the plasma coupling parameters are not large. Due mainly to their importance in theoretical astrophysics, the properties of partially ionized plasmas have been of interest for a long while. More recently, this interest has intensified due to the development of methods for producing partially ionized plasmas in the laboratory. This has opened up large programs of experimental investigation and of practical application. In this paper we consider detailed statistical mechanical methods that explicitly treat the distribution over ionic species and their energy level structure. These detailed approaches are generally characterized as being in the ''chemical picture'' when a free energy expression is minimized or in the ''physical picture'' when the starting point is the grand canonical ensemble. 52 refs., 2 tabs

  3. Simulations of Hall reconnection in partially ionized plasmas

    Science.gov (United States)

    Innocenti, Maria Elena; Jiang, Wei; Lapenta, Giovanni

    2017-04-01

    Magnetic reconnection occurs in the Hall, partially ionized regime in environments as diverse as molecular clouds, protostellar disks and regions of the solar chromosphere. While much is known about Hall reconnection in fully ionized plasmas, Hall reconnection in partially ionized plasmas is, in comparison, still relatively unexplored. This notwithstanding the fact that partial ionization is expected to affect fundamental processes in reconnection such as the transition from the slow, fluid to the fast, kinetic regime, the value of the reconnection rate and the dimensions of the diffusion regions [Malyshkin and Zweibel 2011 , Zweibel et al. 2011]. We present here the first, to our knowledge, fully kinetic simulations of Hall reconnection in partially ionized plasmas. The interaction of electrons and ions with the neutral background is realistically modelled via a Monte Carlo plug-in coded into the semi-implicit, fully kinetic code iPic3D [Markidis 2010]. We simulate a plasma with parameters compatible with the MRX experiments illustrated in Zweibel et al. 2011 and Lawrence et al. 2013, to be able to compare our simulation results with actual experiments. The gas and ion temperature is T=3 eV, the ion to electron temperature ratio is Tr=0.44, ion and electron thermal velocities are calculated accordingly resorting to a reduced mass ratio and a reduced value of the speed of light to reduce the computational costs of the simulations. The initial density of the plasma is set at n= 1.1 1014 cm-3 and is then left free to change during the simulation as a result of gas-plasma interaction. A set of simulations with initial ionisation percentage IP= 0.01, 0.1, 0.2, 0.6 is presented and compared with a reference simulation where no background gas is present (full ionization). In this first set of simulations, we assume to be able to externally control the initial relative densities of gas and plasma. Within this parameter range, the ion but not the electron population is

  4. Re-ionization of a partially ionized plasma by an Alfven wave of moderate amplitude

    International Nuclear Information System (INIS)

    Brennan, M.H.; Sawley, M.L.

    1980-01-01

    The use of forced magnetic-acoustic oscillations to investigate the effect of a torsional hydromagnetic (Alfven) wave pulse of moderate amplitude on the properties of a partially ionized afterglow helium plasma is reported. Observations of the magnetic flux associated with the oscillations, measured at a number of frequencies are used to determine radial density profiles and to provide estimates of plasma temperature. The torsional wave is shown to cause significant re-ionization of the plasma with no corresponding increase in the plasma temperature. The presence of a number of energetic particles is evidenced by the production of a significant number of doubly charged helium ions. (author)

  5. Electrostatic perturbations in partially ionized plasma with the effects of ionization and recombination

    International Nuclear Information System (INIS)

    Vranjes, J.; Tanaka, M.Y.; Kono, M.; Poedts, S.

    2004-01-01

    The behavior of the electrostatic ion acoustic mode in a partially ionized plasma is studied in the presence of collisions which involve processes of ionization and recombination, taking into account the dynamics of the neutrals caused by elastic and inelastic collisions with ions. The application of the model to space plasmas, which are usually subject to gravity, is discussed in detail. A dispersion equation which includes the effects of ionization and recombination is derived and the stability/instability conditions are discussed. Parameters applicable to a region of the upper solar chromosphere are used and the increment of the ion sound wave is calculated yielding an unstable ion sound wave for wavelengths larger than 20 km

  6. Fluid description of multi-component solar partially ionized plasma

    International Nuclear Information System (INIS)

    Khomenko, E.; Collados, M.; Vitas, N.; Díaz, A.

    2014-01-01

    We derive self-consistent formalism for the description of multi-component partially ionized solar plasma, by means of the coupled equations for the charged and neutral components for an arbitrary number of chemical species, and the radiation field. All approximations and assumptions are carefully considered. Generalized Ohm's law is derived for the single-fluid and two-fluid formalism. Our approach is analytical with some order-of-magnitude support calculations. After general equations are developed, we particularize to some frequently considered cases as for the interaction of matter and radiation

  7. Fully differential cross sections for heavy particle impact ionization

    Energy Technology Data Exchange (ETDEWEB)

    McGovern, M; Walters, H R J [Department of Applied Mathematics and Theoretical Physics, Queen' s University, Belfast BT7 1NN (United Kingdom); Assafrao, D; Mohallem, J R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, P.O Box 702, 30123-970 Belo Horizonte, MG (Brazil); Whelan, Colm T, E-mail: mmcgovern06@qub.ac.u [Department of Physics, Old Dominion University, Norfolk, VA 23529-0116 (United States)

    2009-11-15

    We describe a procedure for extracting fully differential ionization cross sections from an impact parameter coupled pseudostate treatment of the collision. Some examples from antiproton impact ionization of atomic Hydrogen are given.

  8. Parabolic versus spherical partial cross sections for photoionization excitation of He near threshold

    International Nuclear Information System (INIS)

    Bouri, C.; Selles, P.; Malegat, L.; Kwato Njock, M. G.

    2006-01-01

    Spherical and parabolic partial cross sections and asymmetry parameters, defined in the ejected electron frame, are presented for photoionization excitation of the helium atom at 0.1 eV above its double ionization threshold. A quantitative law giving the dominant spherical partial wave l dom for each excitation level n is obtained. The parabolic partial cross sections are shown to satisfy the same approximate selection rules as the related Rydberg series of doubly excited states (K,T) n A . The analysis of radial and angular correlations reveals the close relationship between double excitation, ionization excitation, and double ionization. Opposite to a widespread belief, the observed value of the asymmetry parameter is shown to result from the interplay of radial correlations and symmetry constraints, irrespective of angular correlations. Finally, the measurement of parabolic partial cross sections is proposed as a challenge to experimentalists

  9. Alfven wave propagation in a partially ionized plasma

    International Nuclear Information System (INIS)

    Watts, Christopher; Hanna, Jeremy

    2004-01-01

    Results from a laboratory study of the dispersion relation of Alfven waves propagating through a partially ionized plasma are presented. The plasma is generated using a helicon source, creating a high density, current-free discharge, where the source can be adjusted to one of several modes with varying neutral fraction. Depending on the neutral fraction, the measured dispersion curve of shear Alfven waves can change significantly. Measurement results are compared with theoretical predictions of the effect of neutral particles on Alfven wave propagation. In fitting the theory, the neutral fraction is independently estimated using two simple particle transport models, one collisionless, the other collisional. The two models predict comparable neutral fractions, and agree well with the neutral fraction required for the Alfven dispersion theory

  10. Nonlinear acoustic waves in partially ionized collisional plasmas

    International Nuclear Information System (INIS)

    Rao, N.N.; Kaup, D.J.; Shukla, P.K.

    1991-01-01

    Nonlinear propagation of acoustic-type waves in a partially ionized three-component collisional plasma consisting of electrons, ions and neutral particles is investigated. For bidirectional propagation, it is shown that the small- but finite-amplitude waves are governed by the Boussinesq equation, which for unidirectional propagation near the acoustic speed reduces to the usual Korteweg-de Vries equation. For large-amplitude waves, it is demonstrated that the relevant fluid equations are integrable in a stationary frame, and the parameter values for the existence of finite-amplitude solutions are explicitly obtained. In both cases, the different temperatures of the individual species, are taken into account. The relevance of the results to the earth's ionospheric plasma in the lower altitude ranges is pointed out. (author)

  11. On the thermal raleigh problem in partially ionized argon

    International Nuclear Information System (INIS)

    Hutten Mansfeld, A.C.B.

    1976-01-01

    A partially ionized gas is created by the reflection of a shock wave with incident Mach numbers in the range 7 to 10 and an initial pressure of 5 Torr against the cold end wall of a shock tube. Heat exchange between the plasma and this cold wall induces several relaxation processes in the thermal boundary layer. Of these, relaxation of i) the electron and heavy particles temperature and ii) the degree of ionization towards a local thermodynamic equilibrium state are considered. In the model, transport and relaxation processes are treated simultaneously. A classification on the basis of relaxation phenomena is performed, i.e., simplified sets of equations are obtained in a systematic way from the frozen or equilibrium limits of the relaxation processes. A finite difference numerical solution for the different models is obtained. Because the boundary conditions are of mixed type and the relaxation processes show aspects of stiffness, the application of a backward implicit discretization scheme is necessary. As a diagnostic tool, a two wavelength version of the laser schlieren method is used. The measurements provide time histories of both the electron and atom number density gradients

  12. Determination of composition and physical properties of partially ionized plasmas in the function of temperature

    International Nuclear Information System (INIS)

    Zaporowski, B.

    1992-01-01

    The investigations of various kinds of partially ionized plasma were conducted for the pressure of 0.1 MPa and in the range of temperature of 298.15 K to 24000 K. The physical properties of various kinds of partially ionized plasma depend mainly of their composition and temperature. The composition of particular kinds of partially ionized plasmas varies also in the function of temperature. Simultaneous going on of physical and chemical processes in plasma is the reason of difficulties in the calculations of plasma's physical properties. The use of the laws of macroscopic thermodynamics for the calculations of physical properties of partially ionized plasma is impossible. There are enough exact methods for measuring of physical properties of partially ionized plasma. For these reasons the theoretical method using the base of statistic physics was used to calculate the composition and physical properties of various kinds of partially ionized plasma. (author) 2 refs., 2 figs

  13. Partial cross sections of helium satellites at medium photon energies

    Energy Technology Data Exchange (ETDEWEB)

    Wehlitz, R.; Sellin, I.A. [Univ. of Tennessee, Knoxville, TN (United States); Hemmers, O. [Univ. of Nevada, Las Vegas, NV (United States)] [and others

    1997-04-01

    Still of current interest is the important role of single ionization with excitation compared to single ionization alone. The coupling between the electrons and the incoming photon is a single-particle operator. Thus, an excitation in addition to an ionization, leading to a so-called satellite line in a photoelectron spectrum, is entirely due to electron-electron interaction and probes the electron correlation in the ground and final state. Therefore the authors have undertaken the study of the intensity of helium satellites He{sup +}nl (n = 2 - 6) relative to the main photoline (n = 1) as a function of photon energy at photon energies well above threshold up to 900 eV. From these results they could calculate the partial cross-sections of the helium satellites. In order to test the consistency of their satellite-to-1s ratios with published double-to-single photoionization ratios, the authors calculated the double-to-single photoionization ratio from their measured ratios using the theoretical energy-distribution curves of Chang and Poe and Le Rouzo and Dal Cappello which proved to be valid for photon energies below 120 eV. These calculated double-to-single ionization ratios agree fairly well with recent ion measurements. In the lower photon energy range the authors ratios agree better with the ratios of Doerner et al. while for higher photon energies the agreement is better with the values of Levin et al.

  14. Partial cross sections of helium satellites at medium photon energies

    International Nuclear Information System (INIS)

    Wehlitz, R.; Sellin, I.A.; Hemmers, O.

    1997-01-01

    Still of current interest is the important role of single ionization with excitation compared to single ionization alone. The coupling between the electrons and the incoming photon is a single-particle operator. Thus, an excitation in addition to an ionization, leading to a so-called satellite line in a photoelectron spectrum, is entirely due to electron-electron interaction and probes the electron correlation in the ground and final state. Therefore the authors have undertaken the study of the intensity of helium satellites He + nl (n = 2 - 6) relative to the main photoline (n = 1) as a function of photon energy at photon energies well above threshold up to 900 eV. From these results they could calculate the partial cross-sections of the helium satellites. In order to test the consistency of their satellite-to-1s ratios with published double-to-single photoionization ratios, the authors calculated the double-to-single photoionization ratio from their measured ratios using the theoretical energy-distribution curves of Chang and Poe and Le Rouzo and Dal Cappello which proved to be valid for photon energies below 120 eV. These calculated double-to-single ionization ratios agree fairly well with recent ion measurements. In the lower photon energy range the authors ratios agree better with the ratios of Doerner et al. while for higher photon energies the agreement is better with the values of Levin et al

  15. The Electron Temperature of a Partially Ionized Gas in an Electric Field

    International Nuclear Information System (INIS)

    Robben, F.

    1968-03-01

    The electron temperature of a partially ionized gas in an electric field can be determined by the collision rate for momentum transfer and the collision rate for energy transfer. Mean values of these rates are defined such that a simple expression for the electron temperature is obtained, and which depends, among other things, on the ratio of these mean rates. This ratio is calculated in the Lorentz approximation for power law cross sections, and also as a function of the degree of ionization for a helium plasma. It is pointed out that the complete results of refined transport theory can be used in calculating electron mobility and electron temperature in a multicomponent plasma without undue difficulty

  16. The Electron Temperature of a Partially Ionized Gas in an Electric Field

    Energy Technology Data Exchange (ETDEWEB)

    Robben, F

    1968-03-15

    The electron temperature of a partially ionized gas in an electric field can be determined by the collision rate for momentum transfer and the collision rate for energy transfer. Mean values of these rates are defined such that a simple expression for the electron temperature is obtained, and which depends, among other things, on the ratio of these mean rates. This ratio is calculated in the Lorentz approximation for power law cross sections, and also as a function of the degree of ionization for a helium plasma. It is pointed out that the complete results of refined transport theory can be used in calculating electron mobility and electron temperature in a multicomponent plasma without undue difficulty.

  17. COLLISIONLESS SHOCKS IN A PARTIALLY IONIZED MEDIUM. II. BALMER EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Morlino, G.; Bandiera, R.; Blasi, P.; Amato, E. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)

    2012-12-01

    Strong shocks propagating into a partially ionized medium are often associated with optical Balmer lines. This emission is due to impact excitation of neutral hydrogen by hot protons and electrons in the shocked gas. The structure of such Balmer-dominated shocks has been computed in a previous paper, where the distribution function of neutral particles was derived from the appropriate Boltzmann equation including coupling with ions and electrons through charge exchange and ionization. This calculation showed how the presence of neutrals can significantly modify the shock structure through the formation of a neutral-induced precursor ahead of the shock. Here we follow up on our previous work and investigate the properties of the resulting Balmer emission, with the aim of using the observed radiation as a diagnostic tool for shock parameters. Our main focus is on supernova remnant shocks, and we find that, for typical parameters, the H{alpha} emission typically has a three-component spectral profile, where (1) a narrow component originates from upstream cold hydrogen atoms, (2) a broad component comes from hydrogen atoms that have undergone charge exchange with shocked protons downstream of the shock, and (3) an intermediate component is due to hydrogen atoms that have undergone charge exchange with warm protons in the neutral-induced precursor. The relative importance of these three components depends on the shock velocity, on the original degree of ionization, and on the electron-ion temperature equilibration level. The intermediate component, which is the main signature of the presence of a neutral-induced precursor, becomes negligible for shock velocities {approx}< 1500 km s{sup -1}. The width of the intermediate line reflects the temperature in the precursor, while the width of the narrow one is left unaltered by the precursor. In addition, we show that the profiles of both the intermediate and broad components generally depart from a thermal distribution, as a

  18. Total and ionization cross sections of electron scattering by fluorocarbons

    International Nuclear Information System (INIS)

    Antony, B K; Joshipura, K N; Mason, N J

    2005-01-01

    Electron impact total cross sections (50-2000 eV) and total ionization cross sections (threshold to 2000 eV) are calculated for typical plasma etching molecules CF 4 , C 2 F 4 , C 2 F 6 , C 3 F 8 and CF 3 I and the CF x (x 1-3) radicals. The total elastic and inelastic cross sections are determined in the spherical complex potential formalism. The sum of the two gives the total cross section and the total inelastic cross section is used to calculate the total ionization cross sections. The present total and ionization cross sections are found to be consistent with other theories and experimental measurements, where they exist. Our total cross section results for CF x (x = 1-3) radicals presented here are first estimates on these species

  19. Partial cross sections in H- photodetachment

    International Nuclear Information System (INIS)

    Halka, M.

    1993-04-01

    This dissertation reports experimental measurements of partial decay cross sections in the H - photodetachment spectrum. Observed decays of the 1 P 0 H -** (n) doubly-excitedresonances to the H(N=2) continuum are reported for n=2,3, and 4 from 1990 runs in which the author participated. A recent analysis of 1989 data revealing effects of static electric fields on the partial decay spectrum above 13.5 eV is also presented. The experiments were performed at the High Resolution Atomic Beam Facility. the Los Alamos Meson Physics Facility, with a relativistic H - beam (β=0.842)intersecting a ND:YAG laser. Variation of the intersection angle amounts to Doppler-shifting the photon energy, allowing continuous tuning of the laser energy as viewed from the moving ions' frame

  20. Determination of molecular ionization cross sections in an ICR spectrometer

    International Nuclear Information System (INIS)

    Takashima, K.; Riveros, J.M.

    1976-01-01

    Ionization cross sections have been determined for simple gases at 75eV in an ICR spectrometer. Results obtained using a calibrated ion gauge as a pressure indicator yield values which are consistently higher than accepted values by as much as 15%. These results suggest that a more convenient way to measure pressure in ICR experiments might be to record the total ion current and to use the tabulated ionization cross sections where available [pt

  1. Triply differential cross sections for ionization of helium by electrons

    International Nuclear Information System (INIS)

    Brauner, M.; Briggs, J.S.; Broad, J.T.

    1991-01-01

    A correlated three-body continuum wavefunction, already successfully employed to describe hydrogen atom impact ionization, is used to calculate the triply-differential cross section for electron impact ionization of helium. A good description is obtained of all the major structure in the differential cross sections in both symmetric and asymmetric geometries. It is demonstrated how interference between the various projectile-target interactions is necessary to reproduce the experimentally observed structure. (author)

  2. Influence of collective nonideal shielding on fusion reaction in partially ionized classical nonideal plasmas

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2017-04-01

    The collective nonideal effects on the nuclear fusion reaction process are investigated in partially ionized classical nonideal hydrogen plasmas. The effective pseudopotential model taking into account the collective and plasma shielding effects is applied to describe the interaction potential in nonideal plasmas. The analytic expressions of the Sommerfeld parameter, the fusion penetration factor, and the cross section for the nuclear fusion reaction in nonideal plasmas are obtained as functions of the nonideality parameter, Debye length, and relative kinetic energy. It is found that the Sommerfeld parameter is suppressed due to the influence of collective nonideal shielding. However, the collective nonideal shielding is found to enhance the fusion penetration factor in partially ionized classical nonideal plasmas. It is also found that the fusion penetration factors in nonideal plasmas represented by the pseudopotential model are always greater than those in ideal plasmas represented by the Debye-Hückel model. In addition, it is shown that the collective nonideal shielding effect on the fusion penetration factor decreases with an increase of the kinetic energy.

  3. Absolute total and partial dissociative cross sections of pyrimidine at electron and proton intermediate impact velocities

    Energy Technology Data Exchange (ETDEWEB)

    Wolff, Wania, E-mail: wania@if.ufrj.br; Luna, Hugo; Sigaud, Lucas; Montenegro, Eduardo C. [Instituto de Física, Universidade Federal do Rio de Janeiro, PO 68528, 21941-972 Rio de Janeiro, RJ (Brazil); Tavares, Andre C. [Departamento de Física, Pontificia Universidade Católica do Rio de Janeiro, PO 38071, Rua Marquês de São Vicente 225, 22453-900 Rio de Janeiro, RJ (Brazil)

    2014-02-14

    Absolute total non-dissociative and partial dissociative cross sections of pyrimidine were measured for electron impact energies ranging from 70 to 400 eV and for proton impact energies from 125 up to 2500 keV. MOs ionization induced by coulomb interaction were studied by measuring both ionization and partial dissociative cross sections through time of flight mass spectrometry and by obtaining the branching ratios for fragment formation via a model calculation based on the Born approximation. The partial yields and the absolute cross sections measured as a function of the energy combined with the model calculation proved to be a useful tool to determine the vacancy population of the valence MOs from which several sets of fragment ions are produced. It was also a key point to distinguish the dissociation regimes induced by both particles. A comparison with previous experimental results is also presented.

  4. Penning ionization cross sections of excited rare gas atoms

    International Nuclear Information System (INIS)

    Ukai, Masatoshi; Hatano, Yoshihiko.

    1988-01-01

    Electronic energy transfer processes involving excited rare gas atoms play one of the most important roles in ionized gas phenomena. Penning ionization is one of the well known electronic energy transfer processes and has been studied extensively both experimentally and theoretically. The present paper reports the deexcitation (Penning ionization) cross sections of metastable state helium He(2 3 S) and radiative He(2 1 P) atoms in collision with atoms and molecules, which have recently been obtained by the authors' group by using a pulse radiolysis method. Investigation is made of the selected deexcitation cross sections of He(2 3 S) by atoms and molecules in the thermal collisional energy region. Results indicate that the cross sections are strongly dependent on the target molecule. The deexcitation probability of He(2 3 S) per collision increases with the excess electronic energy of He(2 3 S) above the ionization potential of the target atom or molecule. Another investigation, made on the deexcitation of He(2 1 P), suggests that the deexcitation cross section for He(2 1 P) by Ar is determined mainly by the Penning ionization cross section due to a dipole-dipole interaction. Penning ionization due to the dipole-dipole interaction is also important for deexcitation of He(2 1 P) by the target molecules examined. (N.K.)

  5. 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)

  6. Pressure of a partially ionized hydrogen gas : numerical results from exact low temperature expansions

    OpenAIRE

    Alastuey , Angel; Ballenegger , Vincent

    2010-01-01

    8 pages; International audience; We consider a partially ionized hydrogen gas at low densities, where it reduces almost to an ideal mixture made with hydrogen atoms in their ground-state, ionized protons and ionized electrons. By performing systematic low-temperature expansions within the physical picture, in which the system is described as a quantum electron-proton plasma interacting via the Coulomb potential, exact formulae for the first five leading corrections to the ideal Saha equation ...

  7. Comments on evaluation of energy of partial discharges in ionization chambers

    International Nuclear Information System (INIS)

    Lechowski, Z.

    1980-01-01

    A method of evaluation of energy of partial discharges in ionization chambers which are intended for investigation on electric strength of insulating materials is presented. It is demonstrated that an ionization chamber must be considered as a set of discharge sources and that for energy evaluation an amplitude analysis of apparent charge of discharges is useful. (author)

  8. Cross Sections for Inner-Shell Ionization by Electron Impact

    Energy Technology Data Exchange (ETDEWEB)

    Llovet, Xavier, E-mail: xavier@ccit.ub.edu [Centres Científics i Tecnològics, Universitat de Barcelona, Lluís Solé i Sabarís 1-3, 08028 Barcelona (Spain); Powell, Cedric J. [Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8370 (United States); Salvat, Francesc [Facultat de Física (ECM and ICC), Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Jablonski, Aleksander [Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw (Poland)

    2014-03-15

    An analysis is presented of measured and calculated cross sections for inner-shell ionization by electron impact. We describe the essentials of classical and semiclassical models and of quantum approximations for computing ionization cross sections. The emphasis is on the recent formulation of the distorted-wave Born approximation by Bote and Salvat [Phys. Rev. A 77, 042701 (2008)] that has been used to generate an extensive database of cross sections for the ionization of the K shell and the L and M subshells of all elements from hydrogen to einsteinium (Z = 1 to Z = 99) by electrons and positrons with kinetic energies up to 1 GeV. We describe a systematic method for evaluating cross sections for emission of x rays and Auger electrons based on atomic transition probabilities from the Evaluated Atomic Data Library of Perkins et al. [Lawrence Livermore National Laboratory, UCRL-ID-50400, 1991]. We made an extensive comparison of measured K-shell, L-subshell, and M-subshell ionization cross sections and of Lα x-ray production cross sections with the corresponding calculated cross sections. We identified elements for which there were at least three (for K shells) or two (for L and M subshells) mutually consistent sets of cross-section measurements and for which the cross sections varied with energy as expected by theory. The overall average root-mean-square deviation between the measured and calculated cross sections was 10.9% and the overall average deviation was −2.5%. This degree of agreement between measured and calculated ionization and x-ray production cross sections was considered to be very satisfactory given the difficulties of these measurements.

  9. Cross section data for ionization of important cyanides

    International Nuclear Information System (INIS)

    Kaur, Jaspreet; Antony, Bobby

    2015-01-01

    Highlights: • Multi centre spherical complex optical potential formalism used to find the CS. • Effective method (CSP-ic) to derive ionization contribution from inelastic CS. • Result shows excellent accord with previous results and consistent behaviour. • Maiden attempt to find CS for many cyanide molecules. • Strong correlation observed between peak of ionization with target properties. - Abstract: This article presents cross section calculations for interactions of important cyanides with electrons possessing energies beginning from ionization threshold of the target molecule to 5 keV. These data are pursued to meet the ever increasing demand for cross sections by the relevant atomic and molecular community for modelling astrophysical, atmospheric and technological domains. The calculations have been executed using an amalgam of multi centre spherical complex optical potential (MSCOP) formalism and complex scattering potential-ionization contribution (CSP-ic) method. Cross sections are compared with experimental and theoretical data wherever available. Strong correlations are observed for the cross sections which affirms consistent and reliable cross sections. Isomeric effect has been interpreted using variation of cross section with structure and target properties. Our cross sections will be tabulated in atomic collision database for use in modelling various statistical and dynamical quantities.

  10. Cross section data for ionization of important cyanides

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Jaspreet; Antony, Bobby, E-mail: bka.ism@gmail.com

    2015-11-15

    Highlights: • Multi centre spherical complex optical potential formalism used to find the CS. • Effective method (CSP-ic) to derive ionization contribution from inelastic CS. • Result shows excellent accord with previous results and consistent behaviour. • Maiden attempt to find CS for many cyanide molecules. • Strong correlation observed between peak of ionization with target properties. - Abstract: This article presents cross section calculations for interactions of important cyanides with electrons possessing energies beginning from ionization threshold of the target molecule to 5 keV. These data are pursued to meet the ever increasing demand for cross sections by the relevant atomic and molecular community for modelling astrophysical, atmospheric and technological domains. The calculations have been executed using an amalgam of multi centre spherical complex optical potential (MSCOP) formalism and complex scattering potential-ionization contribution (CSP-ic) method. Cross sections are compared with experimental and theoretical data wherever available. Strong correlations are observed for the cross sections which affirms consistent and reliable cross sections. Isomeric effect has been interpreted using variation of cross section with structure and target properties. Our cross sections will be tabulated in atomic collision database for use in modelling various statistical and dynamical quantities.

  11. Quantum statistical mechanics of dense partially ionized hydrogen.

    Science.gov (United States)

    Dewitt, H. E.; Rogers, F. J.

    1972-01-01

    The theory of dense hydrogenic plasmas beginning with the two component quantum grand partition function is reviewed. It is shown that ionization equilibrium and molecular dissociation equilibrium can be treated in the same manner with proper consideration of all two-body states. A quantum perturbation expansion is used to give an accurate calculation of the equation of state of the gas for any degree of dissociation and ionization. In this theory, the effective interaction between any two charges is the dynamic screened potential obtained from the plasma dielectric function. We make the static approximation; and we carry out detailed numerical calculations with the bound and scattering states of the Debye potential, using the Beth-Uhlenbeck form of the quantum second virial coefficient. We compare our results with calculations from the Saha equation.

  12. Saha and temperature relaxation approximations for the study of ionization instability in partially ionized plasma

    International Nuclear Information System (INIS)

    Numano, M.

    1976-01-01

    The growth rates for the ionization instability obtained using the Saha and temperature relaxation approximations are compared with those obtained from an exact treatment, and the requirements for validity of these two approximations are obtained analytically. For the range of plasma parameters pertinent to MHD power generation it is found that the Saha approximation is valid for relatively high electron temperature, which it becomes inapplicable as the electron temperature is decreased. On the other hand, the temperature relaxation approximation is accurate over a wide range of electron temperature. It is found also that the marginal condition for the ionization instability is correctly obtained from both approximations. (author)

  13. A drift-ordered short mean-free path description of a partially ionized magnetized plasma

    International Nuclear Information System (INIS)

    Simakov, Andrei N

    2009-01-01

    Neutral particles that are present at the edge of plasma magnetic confinement devices can play an important role in energy and momentum transport, and their effects should be accounted for. This work uses the drift ordering to derive a closed fluid description for a collisional, magnetized, partially ionized plasma. Charge-exchange, ionization and recombination processes are taken into account. It is assumed that electron distribution function is unaffected by atomic processes, so that electron-ion momentum and energy exchange are described by the usual expressions for a fully ionized plasma, and that neutral-neutral collisions are unimportant. The collisional fluid equations derived herein generalize the drift-ordered description of a fully ionized collisional plasma (Catto P J et al 2004 Phys. Plasmas 11 90), agree with the MHD-ordered description of a partially ionized plasma (Helander P et al 1994 Phys. Plasmas 1 3174) in the large-flow limit and can be used to describe both turbulent and collisional behavior of a partially ionized plasma.

  14. ALFVÉN WAVES IN A PARTIALLY IONIZED TWO-FLUID PLASMA

    International Nuclear Information System (INIS)

    Soler, R.; Ballester, J. L.; Terradas, J.; Carbonell, M.

    2013-01-01

    Alfvén waves are a particular class of magnetohydrodynamic waves relevant in many astrophysical and laboratory plasmas. In partially ionized plasmas the dynamics of Alfvén waves is affected by the interaction between ionized and neutral species. Here we study Alfvén waves in a partially ionized plasma from the theoretical point of view using the two-fluid description. We consider that the plasma is composed of an ion-electron fluid and a neutral fluid, which interact by means of particle collisions. To keep our investigation as general as possible, we take the neutral-ion collision frequency and the ionization degree as free parameters. First, we perform a normal mode analysis. We find the modification due to neutral-ion collisions of the wave frequencies and study the temporal and spatial attenuation of the waves. In addition, we discuss the presence of cutoff values of the wavelength that constrain the existence of oscillatory standing waves in weakly ionized plasmas. Later, we go beyond the normal mode approach and solve the initial-value problem in order to study the time-dependent evolution of the wave perturbations in the two fluids. An application to Alfvén waves in the low solar atmospheric plasma is performed and the implication of partial ionization for the energy flux is discussed.

  15. Adiabatic theory of Wannier threshold laws and ionization cross sections

    International Nuclear Information System (INIS)

    Macek, J.H.; Ovchinnikov, S.Y.

    1994-01-01

    Adiabatic energy eigenvalues of H 2 + are computed for complex values of the internuclear distance R. The infinite number of bound-state eigenenergies are represented by a function ε(R) that is single valued on a multisheeted Riemann surface. A region is found where ε(R) and the corresponding eigenfunctions exhibit harmonic-oscillator structure characteristic of electron motion on a potential saddle. The Schroedinger equation is solved in the adiabatic approximation along a path in the complex R plane to compute ionization cross sections. The cross section thus obtained joins the Wannier threshold region with the keV energy region, but the exponent near the ionization threshold disagrees with well-accepted values. Accepted values are obtained when a lowest-order diabatic correction is employed, indicating that adiabatic approximations do not give the correct zero velocity limit for ionization cross sections. Semiclassical eigenvalues for general top-of-barrier motion are given and the theory is applied to the ionization of atomic hydrogen by electron impact. The theory with a first diabatic correction gives the Wannier threshold law even for this case

  16. Electron-impact ionization cross section of rubidium

    International Nuclear Information System (INIS)

    Kim, Y.; Migdalek, J.; Siegel, W.; Bieron, J.

    1998-01-01

    A theoretical model for electron-impact ionization cross section has been applied to Rb and the theoretical cross section (from the threshold to 1 keV in incident energy) is in good agreement with the recent experimental data obtained using Rb atoms trapped in a magneto-optical trap. The theoretical model, called the binary-encounter endash dipole (BED) model, combines a modified Mott cross section with the high-energy behavior of Born cross sections. To obtain the continuum dipole oscillator strength df/dE of the 5s electron required in the BED model, we used Dirac-Fock continuum wave functions with a core polarization potential that reproduced the known position of the Cooper minimum in the photoionization cross section. For inner-shell ionization, we used a simpler version of df/dE, which retained the hydrogenic shape. The contributions of the 4p→4d, 5s, and 5p autoionizing excitations were estimated using the plane-wave Born approximation. As a by-product, we also present the dipole oscillator strengths for the 5s→np 1/2 and 5s→np 3/2 transitions for high principal quantum numbers n near the ionization threshold obtained from the Dirac-Fock wave functions with the same core polarization potential as that used for the continuum wave functions. copyright 1998 The American Physical Society

  17. Absolute cross-section measurements of inner-shell ionization

    Science.gov (United States)

    Schneider, Hans; Tobehn, Ingo; Ebel, Frank; Hippler, Rainer

    1994-12-01

    Cross section ratios for K- and L-shell ionization of thin silver and gold targets by positron and electron impact have been determined at projectile energies of 30 70 keV. The experimental results are confirmed by calculations in plane wave Born approximation (PWBA) which include an electron exchange term and account for the deceleration or acceleration of the incident projectile in the nuclear field of the target atom. We report first absolute cross sections for K- and L-shell ionization of silver and gold targets by lepton impact in the threshold region. We have measured the corresponding cross sections for electron (e-) impact with an electron gun and the same experimental set-up.

  18. Effects of ionizing radiation and partial hepatectomy on messenger RNA synthesis

    International Nuclear Information System (INIS)

    Abdel-Halim, M.N.

    1979-01-01

    Newly synthesized messenger RNA, as measured by a 40 min uptake of the radioactive precursor (6- 14 C) orotic acid, was studied in the regenerating livers of non-irradiated and gamma-irradiated (1800 rad) adrenal-intact and adrenalectomized rats 24 and 48 hours after partial hepatectomy. Two groups of rats, one with and one without adrenal glands were each divided into four subgroups: (1) control rats, (2) irradiated rats, (3) partially hepatectomized rats and (4) irradiated, partially hepatectomized rats. The radioactive profile of polyribosome formation and distribution was determined by sucrose density gradient centrifugation (10 to 40 per cent). The result of this study indicates that ionizing radiation decreases the synthesis of newly formed messenger RNA in regenerating livers of adrenal-intact rats. However, adrenalectomy largely abolished that inhibition. These data suggest that the decrease in messenger RNA synthesis may be explained by the disturbance of adrenal hormones induced by partial hepatectomy and ionizing radiation. (author)

  19. A semi-empirical concept for the calculation of electron-impact ionization cross sections of neutral and ionized fullerenes

    International Nuclear Information System (INIS)

    Deutsch, H.; Scheier, P.; Maerk, T.D.; Becker, K.

    2002-01-01

    A semi-empirical approach to the calculation of cross section functions (absolute value and energy dependence) for the electron-impact ionization of several neutral and ionized fullerenes C 60 n+ (n =0-3) was developed, for which reliable experimental data have been reported. In particular, it is proposed a modification of the simplistic assumption that the ionization cross section of a cluster/fullerene is given as the product of the monomer ionization cross section and a factor m a , where 'm' is the number of monomers in the ensemble and 'a' is a constant. A comparison between these calculations and the available experimental data reveals good agreement for n = 0,103. In the case of ionization of C 60 2+ (n = 2) the calculation lies significantly below the measured cross section which it was interpret as an indication that additional indirect ionization processes are present for this charge state. (nevyjel)

  20. Influence of relaxation processes on the structure of a thermal boundary layer in partially ionized argon

    International Nuclear Information System (INIS)

    Dongen, M.E.H. van; Eck, R.B. van P. van; Hagebeuk, H.J.L.; Hirschberg, A.; Hutten-Mansfeld, A.C.B.; Jager, H.J.; Willems, J.F.H.

    1981-01-01

    A model for the unsteady thermal boundary-layer development at the end wall of a shock tube, in partially ionized atmospheric argon, is proposed. Consideration is given to ionization and thermal relaxation processes. In order to obtain some insight into the influence of the relaxation processes on the structure of the boundary layer, a study of the frozen and equilibrium limits has been carried out. The transition from a near-equilibrium situation in the outer part of the boundary layer towards a frozen situation near the wall is determined numerically. Experimental data on the electron and atom density profiles obtained from laser schlieren and absorption measurements are presented. A quantitative agreement between theory and experiment is found for a moderate degree of ionization (3%). At a higher degree of ionization the structure of the boundary layer is dominated by the influence of radiation cooling, which has been neglected in the model. (author)

  1. Partial cross sections near the higher resonances

    International Nuclear Information System (INIS)

    Falk-Vairant, P.; Valladas, G.

    1961-07-01

    As a continuation of the report given at the 10. Rochester Conference, recent measurements of charge-exchange cross section and π 0 production in π - -p interactions are presented here. Section 1 gives a summary of the known results for the elastic, inelastic, and charge-exchange cross sections. Section 2 presents the behavior of the cross sections in the T=1/2 state, in order to discuss the resonances at 600 and 890 MeV. Section 3 discusses the charge-exchange scattering and the interference term between the T=1/2 and T=3/2 states. Section 4 presents some comments on inelastic processes. This report is reprinted from 'Reviews of Modern Physics', Vol. 33, No. 3, 362-367, July, 1961

  2. PHYSICS OF A PARTIALLY IONIZED GAS RELEVANT TO GALAXY FORMATION SIMULATIONS-THE IONIZATION POTENTIAL ENERGY RESERVOIR

    Energy Technology Data Exchange (ETDEWEB)

    Vandenbroucke, B.; De Rijcke, S.; Schroyen, J. [Department of Physics and Astronomy, Ghent University, Krijgslaan 281, S9, B-9000 Gent (Belgium); Jachowicz, N. [Department of Physics and Astronomy, Ghent University, Proeftuinstraat 86, B-9000 Gent (Belgium)

    2013-07-01

    Simulation codes for galaxy formation and evolution take on board as many physical processes as possible beyond the standard gravitational and hydrodynamical physics. Most of this extra physics takes place below the resolution level of the simulations and is added in a ''sub-grid'' fashion. However, these sub-grid processes affect the macroscopic hydrodynamical properties of the gas and thus couple to the ''on-grid'' physics that is explicitly integrated during the simulation. In this paper, we focus on the link between partial ionization and the hydrodynamical equations. We show that the energy stored in ions and free electrons constitutes a potential energy term which breaks the linear dependence of the internal energy on temperature. Correctly taking into account ionization hence requires modifying both the equation of state and the energy-temperature relation. We implemented these changes in the cosmological simulation code GADGET2. As an example of the effects of these changes, we study the propagation of Sedov-Taylor shock waves through an ionizing medium. This serves as a proxy for the absorption of supernova feedback energy by the interstellar medium. Depending on the density and temperature of the surrounding gas, we find that up to 50% of the feedback energy is spent ionizing the gas rather than heating it. Thus, it can be expected that properly taking into account ionization effects in galaxy evolution simulations will drastically reduce the effects of thermal feedback. To the best of our knowledge, this potential energy term is not used in current simulations of galaxy formation and evolution.

  3. PHYSICS OF A PARTIALLY IONIZED GAS RELEVANT TO GALAXY FORMATION SIMULATIONS—THE IONIZATION POTENTIAL ENERGY RESERVOIR

    International Nuclear Information System (INIS)

    Vandenbroucke, B.; De Rijcke, S.; Schroyen, J.; Jachowicz, N.

    2013-01-01

    Simulation codes for galaxy formation and evolution take on board as many physical processes as possible beyond the standard gravitational and hydrodynamical physics. Most of this extra physics takes place below the resolution level of the simulations and is added in a ''sub-grid'' fashion. However, these sub-grid processes affect the macroscopic hydrodynamical properties of the gas and thus couple to the ''on-grid'' physics that is explicitly integrated during the simulation. In this paper, we focus on the link between partial ionization and the hydrodynamical equations. We show that the energy stored in ions and free electrons constitutes a potential energy term which breaks the linear dependence of the internal energy on temperature. Correctly taking into account ionization hence requires modifying both the equation of state and the energy-temperature relation. We implemented these changes in the cosmological simulation code GADGET2. As an example of the effects of these changes, we study the propagation of Sedov-Taylor shock waves through an ionizing medium. This serves as a proxy for the absorption of supernova feedback energy by the interstellar medium. Depending on the density and temperature of the surrounding gas, we find that up to 50% of the feedback energy is spent ionizing the gas rather than heating it. Thus, it can be expected that properly taking into account ionization effects in galaxy evolution simulations will drastically reduce the effects of thermal feedback. To the best of our knowledge, this potential energy term is not used in current simulations of galaxy formation and evolution.

  4. Enzymatic digestibility of peptides cross-linked by ionizing radiation

    International Nuclear Information System (INIS)

    Dizdaroglu, M.; Gajewski, E.; Simic, M.G.

    1984-01-01

    Digestibility by proteolytic enzymes of peptides cross-linked by ionizing radiation was investigated. Small peptides of alanine and phenylalanine were chosen as model compounds and aminopeptidases and carboxypeptidases were used as proteolytic enzymes. Peptides exposed to γ-radiation in aqueous solution were analysed by high-performance liquid chromatography before and after hydrolysis by aminopeptidase M, leucine aminopeptidase carboxypeptidase A and carboxypeptidase Y. The results obtained clearly demonstrate the different actions of these enzymes on cross-linked aliphatic and aromatic peptides. Peptide bonds of cross-linked dipeptides of alanine were completely resistant to enzymatic hydrolysis whereas the enzymes, except for carboxypeptidase Y, cleaved all peptide bonds of cross-linked peptides of phenylalanine. The actions of the enzymes on these particular compounds are discussed in detail. (author)

  5. Screening of ionic cores in partially ionized plasmas within linear response

    International Nuclear Information System (INIS)

    Gericke, D. O.; Vorberger, J.; Wuensch, K.; Gregori, G.

    2010-01-01

    We employ a pseudopotential approach to investigate the screening of ionic cores in partially ionized plasmas. Here, the effect of the tightly bound electrons is condensed into an effective potential between the (free) valence electrons and the ionic cores. Even for weak electron-ion coupling, the corresponding screening clouds show strong modifications from the Debye result for elements heavier than helium. Modifications of the theoretically predicted x-ray scattering signal and implications on measurements are discussed.

  6. Near threshold electron impact ionization cross section for tellurium atoms

    International Nuclear Information System (INIS)

    Chipev, F.F.; Chernyshova, I.V.; Kontros, J.E.; Shpenik, O.B.

    2004-01-01

    Full text: Up today electron-impact ionization is one of the most intensively investigated processes in atomic and molecular physics [1]. These experiments however, are associated with difficulties: high temperatures and densities are required to produce atomic beams and monochromatic intensive electron beams. A crossed electron and atomic beams scattering geometry was employed to measure the ionization efficiency curve for tellurium atoms. Our electron spectrometer comprises two serially mounted hypocycloidal electron energy analyzers [2], the first being the monochromator and the second - the scattered electron analyzer. The whole spectrometer is immersed into the homogenous magnetic field. Great care was taken in selecting the value of the extracting potential at the electrode, mounted normally to the atomic beam direction. By careful choosing this potential as low as possible (∼1.4 V), its influence on the motion of the monochromatized electrons in the collision region was minimized and the full collection of the formed ions was reached. The atom beam was produced using a compact effusion source made of the stainless steel with a microchannel exit to minimise the angular divergency of the beam. The temperature of the microchannel plate was taken about 50 K higher than that of the metal vapour in the heated reservoir. This atomic beam source enabled to produce an atomic beam with the concentration of two orders of magnitude higher than that in the case of a standard effusion source. A typical value of the electron energy spread was 0.15 eV (FWHM) in the 0.1-15 eV energy range. The primary electron beam current was equal to 10 -7 A. Such values of electron energy spread and beam current for the primary electron beam passing through the collision chamber were chosen to provide identical conditions for carrying out all the measurements. The energy scale was calibrated with the accuracy of ± 0.05 eV. The measured ionization cross-section normalized to the results

  7. Survey of experimental and theoretical electron-impact ionization cross sections for transition metal ions in low stages of ionization

    International Nuclear Information System (INIS)

    Pindzola, M.S.; Griffin, D.C.; Bottcher, C.

    1985-03-01

    Electron-ion crossed beams measurements and distorted-wave theory have been employed to make a study of electron-impact ionization for transition metal ions in low stages of ionization. The atomic ions Ti+, Ti 2 +, Ti 3 +, Fe+, Fe 2 +, Fe 3 +, Fe 4 +, Ni+, Ni 2 +, Ni 3 +, Cu+, Cu 2 +, and Cu 3 + are examined

  8. DAMPING OF MAGNETOHYDRODYNAMIC TURBULENCE IN PARTIALLY IONIZED PLASMA: IMPLICATIONS FOR COSMIC RAY PROPAGATION

    International Nuclear Information System (INIS)

    Xu, Siyao; Yan, Huirong; Lazarian, A.

    2016-01-01

    We study the damping processes of both incompressible and compressible magnetohydrodynamic (MHD) turbulence in a partially ionized medium. We start from the linear analysis of MHD waves, applying both single-fluid and two-fluid treatments. The damping rates derived from the linear analysis are then used in determining the damping scales of MHD turbulence. The physical connection between the damping scale of MHD turbulence and the cutoff boundary of linear MHD waves is investigated. We find two branches of slow modes propagating in ions and neutrals, respectively, below the damping scale of slow MHD turbulence, and offer a thorough discussion of their propagation and dissipation behavior. Our analytical results are shown to be applicable in a variety of partially ionized interstellar medium (ISM) phases and the solar chromosphere. The importance of neutral viscosity in damping the Alfvenic turbulence in the interstellar warm neutral medium and the solar chromosphere is demonstrated. As a significant astrophysical utility, we introduce damping effects to the propagation of cosmic rays in partially ionized ISM. The important role of turbulence damping in both transit-time damping and gyroresonance is identified.

  9. Total and partial recombination cross sections for F6+

    International Nuclear Information System (INIS)

    Mitnik, D.M.; Pindzola, M.S.; Badnell, N.R.

    1999-01-01

    Total and partial recombination cross sections for F 6+ are calculated using close-coupling and distorted-wave theory. For total cross sections, close-coupling and distorted-wave results, which include interference between the radiative and dielectronic pathways, are found to be in good agreement with distorted-wave results based on a sum of independent processes. Total cross sections near zero energy are dominated by contributions from low-energy dielectronic recombination resonances. For partial cross sections, the close-coupling and distorted-wave theories predict strong interference for recombination into the final recombined ground state 1s 2 2s 21 S 0 of F 5+ , but only weak interference for recombination into the levels of the 1s 2 2s2p configuration. copyright 1999 The American Physical Society

  10. ANALYTIC FITS FOR PARTIAL PHOTOIONIZATION CROSS-SECTIONS

    NARCIS (Netherlands)

    VERNER, DA; YAKOVLEV, DG

    We present a compact, uniform and complete set of analytic fits to the partial Hartree-Dirac-Slater photoionization cross sections for the ground state shells of all atoms and ions of elements from H to Zn (Z less-than-or-equal-to 30). Comparison with experiment and theory demonstrates generally

  11. DYNAMICS OF CORONAL RAIN AND DESCENDING PLASMA BLOBS IN SOLAR PROMINENCES. II. PARTIALLY IONIZED CASE

    Energy Technology Data Exchange (ETDEWEB)

    Oliver, R.; Soler, R.; Terradas, J. [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Zaqarashvili, T. V., E-mail: ramon.oliver@uib.es [Institute of Physics, IGAM, University of Graz, Universitätsplatz 5, 8010, Graz (Austria)

    2016-02-20

    Coronal rain clumps and prominence knots are dense condensations with chromospheric to transition region temperatures that fall down in the much hotter corona. Their typical speeds are in the range 30–150 km s{sup −1} and of the order of 10–30 km s{sup −1}, respectively, i.e., they are considerably smaller than free-fall velocities. These cold blobs contain a mixture of ionized and neutral material that must be dynamically coupled in order to fall together, as observed. We investigate this coupling by means of hydrodynamic simulations in which the coupling arises from the friction between ions and neutrals. The numerical simulations presented here are an extension of those of Oliver et al. to the partially ionized case. We find that, although the relative drift speed between the two species is smaller than 1 m s{sup −1} at the blob center, it is sufficient to produce the forces required to strongly couple charged particles and neutrals. The ionization degree has no discernible effect on the main results of our previous work for a fully ionized plasma: the condensation has an initial acceleration phase followed by a period with roughly constant velocity, and, in addition, the maximum descending speed is clearly correlated with the ratio of initial blob to environment density.

  12. Formation of β-FeSi 2 thin films by partially ionized vapor deposition

    Science.gov (United States)

    Harada, Noriyuki; Takai, Hiroshi

    2003-05-01

    The partially ionized vapor deposition (PIVD) is proposed as a new method to realize low temperature formation of β-FeSi 2 thin films. In this method, Fe is evaporated by E-gun and a few percents of Fe atoms are ionized. We have investigated influences of the ion content and the accelerating voltage of Fe ions on the structural properties of β-FeSi 2 films deposited on Si substrates. It was confirmed that β-FeSi 2 can be formed on Si(1 0 0) substrate by PIVD even at substrate temperature as low as 350, while FeSi by the conventional vacuum deposition. It was concluded that the influence of Fe ions on preferential orientation of β-FeSi 2 depends strongly on the content and the acceleration energy of ions.

  13. Formation of {beta}-FeSi{sub 2} thin films by partially ionized vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Noriyuki; Takai, Hiroshi

    2003-05-01

    The partially ionized vapor deposition (PIVD) is proposed as a new method to realize low temperature formation of {beta}-FeSi{sub 2} thin films. In this method, Fe is evaporated by E-gun and a few percents of Fe atoms are ionized. We have investigated influences of the ion content and the accelerating voltage of Fe ions on the structural properties of {beta}-FeSi{sub 2} films deposited on Si substrates. It was confirmed that {beta}-FeSi{sub 2} can be formed on Si(1 0 0) substrate by PIVD even at substrate temperature as low as 350, while FeSi by the conventional vacuum deposition. It was concluded that the influence of Fe ions on preferential orientation of {beta}-FeSi{sub 2} depends strongly on the content and the acceleration energy of ions.

  14. Advanced carbon-based material C60 modification using partially ionized cluster and energetic beams

    International Nuclear Information System (INIS)

    Du Yuancheng; Ren Zhongmin; Ning Zhifeng; Xu Ning; Li Fuming

    1997-01-01

    Two processes have been undertaken using Partially ionized cluster deposition (PICBD) and energetic ion bombardment beams deposition (IBD) respectively. C 60 films deposited by PICBD at V=0 and 65 V, which result in highly textured close-packed structure in orientation (110) and being more polycrystalline respectively, the resistance of C 60 films to oxygen diffusion contamination will be improved. In the case of PICBD, the ionized C 60 soccer-balls molecules in the evaporation beams will be fragmented in collision with the substrate under the elevated accelerating fields Va. As a new synthetic IBD processing, two low energy (400 and 1000 eV) nitrogen ion beams have been used to bombard C 60 films to synthesize the carbon nitride films

  15. (n,{alpha}) cross section measurement of gaseous sample using gridded ionization chamber. Cross section determination

    Energy Technology Data Exchange (ETDEWEB)

    Sanami, Toshiya; Baba, Mamoru; Saito, Keiichiro; Ibara, Yasutaka; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

    1997-03-01

    We are developing a method of (n,{alpha}) cross section measurement using gaseous samples in a gridded ionization chamber (GIC). This method enables cross section measurements in large solid angle without the distortion by the energy loss in a sample, but requires a method to estimate the detection efficiency. We solve this problem by using GIC signals and a tight neutron collimation. The validity of this method was confirmed through the {sup 12}C(n,{alpha}{sub 0}){sup 9}Be measurement. We applied this method to the {sup 16}O(n,{alpha}){sup 13}C cross section around 14.1 MeV. (author)

  16. How to identify partial exposures to ionizing radiation? Proposal for a cytogenetic method

    International Nuclear Information System (INIS)

    Fernandes, T.S.; Silva, E.B.; Pinto, M.M.P.L.; Amaral, A.; Lloyd, David

    2013-01-01

    In cases of radiological incidents or in occupational exposures to ionizing radiation, the majority of exposures are not related to the total body, but only partial. In this context, if the cytogenetic dosimetry is performed, there will be an underestimation of the absorbed dose due to the dilution of irradiated cells with non-irradiated cells. Considering the norms of NR 32 - Safety and Health in the Work of Health Service - which recommends cytogenetic dosimetry in the investigation of accidental exposures to ionizing radiations, it is necessary to develop of a tool to provide a better identification of partial exposures. With this aim, a partial body exposure was simulated by mixing, in vitro, 70% of blood irradiated with 4 Gy of X-rays with 30% of unirradiated blood from the same healthy donor. Aliquots of this mixture were cultured for 48 and 72 hours. Prolonging the time of cell culture from 48 to 72 hours produced no significant change in the yield of dicentrics. However, when only M1 (first division cells) were analyzed, the frequency of dicentrics per cell was increased. Prolonging the time of cell culture allowed cells in mitotic delay by irradiation to reach metaphase, and thus provides enough time for the damage to be visualized. The results of this research present the proposed method as an important tool in the investigation of exposed individuals, allowing associating the cytogenetic analysis with the real percentage of irradiated cells, contributing significantly for the decision making in terms of occupational health. (author)

  17. On the effect of electron's runaway in partially ionized hydrogen semiclassical nonideal plasma

    International Nuclear Information System (INIS)

    Turekhanova, K.M.

    2011-01-01

    Complete text of publication follows. The effect of runaway electrons occurs frequently in tokamak plasmas. The majority of experiments in tokamak research have been devoted to the study of confinement properties of runaway electrons. Runaway electrons are reason of various destroying untolarance in tokamak plasmas. At high plasma density, when the critical energy is comparable with the rest energy the multiplication of runaway electrons accelerate at the sacrifice of increase of plasma density. The plasma conductivity is determined by electrons with energy several times higher than the thermal one and does not practically depend on slower electrons distribution. It is important to analyze the probability of runaway electrons at investigation of physical properties of nonideal plasmas under external electric field and running numerical simulations of their. The present paper is devoted to the investigation of effect of runaway electrons in partially ionized hydrogen dense plasma using the effective potentials of particle's interaction. At the investigation of composition of plasma we used the Saha equation with corrections to nonideality (lowering of ionization potentials). The Saha equation was solved for obtaining of plasma ionization stages at the different number density and temperature. As well, when take into account quantum-mechanical diffraction and screening effects, whereas free path of electrons increases with increase of plasma coupling parameter. The condition for appearance of runaway electrons in semiclassical partially ionized plasma is more favorable in regime of dense plasma. In summary it means that the probability of runaway electron in dense plasma is more than the same in rarified plasma that is possibly connected with formation of some ordered structures in dense plasma.

  18. Electron-impact ionization doubly differential cross sections of helium

    International Nuclear Information System (INIS)

    Bray, Igor; Fursa, Dmitry V; Stelbovics, Andris T

    2003-01-01

    The convergent close-coupling (CCC) method is applied to the calculation of electron-helium ionization doubly differential cross sections (DDCSs) at low to intermediate incident energies. We re-examine the CCC calculations and measurements of Roeder et al (1997 J. Phys. B: At. Mol. Opt. Phys. 30 1309-22) by making allowance for the step-function behaviour of the underlying CCC-calculated amplitudes. As done previously, the experimental DDCS were normalized at energies below 100 eV using the 100 eV CCC calculation to determine analyser properties at several secondary energies. In addition, substantially larger calculations are presented, to check the convergence. The agreement between the experiment and the calculations as a whole is much improved on the situation reported earlier

  19. What fills the space between the partially ionized clouds in the local interstellar medium

    International Nuclear Information System (INIS)

    Linsky, Jeffrey; Redfield, Seth

    2015-01-01

    The interstellar matter located between the warm clouds in the LISM and in the Local Cavity is now thought to be photoionized gas with temperatures in the range 10,000-20,000 K. While the hot stars ε CMa and β CMa are the primary photoionizing sources in the LISM, hot white dwarfs also contribute. We consider whether the Stromgren sphere gas produced by very local hot white dwarfs like Sirius B can be important in explaining the local intercloud gas. We find that the Stromgren sphere of Sirius can at least partially explain the intercloud gas in the lines of sight to several nearby stars. We also suggest that the partially ionized warm clouds like the Local Interstellar Cloud in which the Sun is located may be in part Strömgren sphere shells

  20. Partial Photoionization Cross Sections and Angular Distributions for Double Excitation of Helium up to the N=13 Threshold

    International Nuclear Information System (INIS)

    Czasch, A.; Schoeffler, M.; Hattass, M.; Schoessler, S.; Jahnke, T.; Weber, Th.; Staudte, A.; Titze, J.; Wimmer, C.; Kammer, S.; Weckenbrock, M.; Voss, S.; Grisenti, R.E.; Jagutzki, O.; Schmidt, L.Ph.H.; Schmidt-Boecking, H.; Doerner, R.; Rost, J.M.; Schneider, T.; Liu, C.-N.

    2005-01-01

    Partial photoionization cross sections σ N (E γ ) and photoelectron angular distributions β N (E γ ) were measured for the final ionic states He + (N>4) in the region between the N=8 and N=13 thresholds (E γ >78.155 eV) using the cold target recoil ion momentum spectroscopy technique (COLTRIMS). Comparison of the experimental data with two independent sets of theoretical predictions reveals disagreement for the branching ratios to the various He N + states. The angular distributions just below the double ionization threshold suggest an excitation process for highly excited N states similar to the Wannier mechanism for double ionization

  1. Influence of partial ionization and scattering states on the solar interior structure

    International Nuclear Information System (INIS)

    Ulrich, R.K.

    1982-01-01

    The equation of state for the solar interior is normally assumed to be a fully ionized gas corrected by the Debye-Hueckel Coulomb interaction, partial degeneracy, and radiation pressure. The assumption of full ionization is dropped in this paper, and the influence of scattering states is included. The theory of scattering states appears to be new to astrophysics. This theory has been developed by Larkin and is discussed thoroughly by Ebeling, Kraft, and Kremp. The effect of scattering states eliminates the need to invoke a process of ''pressure ionization'' for which no satisfactory theory exists. Six solar models which include varying forms of the equation of state are discussed. The Saha equation without scattering states gives a neutrino counting rate of 7.41 SNU for the 37 Cl experiment, while assumed ionization for T>3 x 10 5 K gives 8.87 SNU, and the Saha equation with the lowest order effect of scattering states (Planck-Larkin equation) gives 8.83 SNU. Inclusion of the second virial coefficient due to scattering states brings the result to 9.02 SNU. The changes of quantities such as central temperature and the temperature at the base of the convective envelope are small and bear a similar relationship among the models. The initial hydrogen abundance of the model including the second virial coefficient due to scattering states is in good agreement with that found for the Orion nebula and B stars, i.e., log (N/sub He//N/sub H/)+12 = 10.97

  2. Calculated Cross Sections for the Electron Impact Ionization of Molecular Ions

    Science.gov (United States)

    Deutsch, H.; Becker, K.; Defrance, P.; Onthong, U.; Parajuli, R.; Probst, M.; Matt-Leubner, S.; Maerk, T.

    2002-10-01

    We report the results of the application of the semi- classical Deutsch-Märk (DM) formalism to the calculation of the absolute electron-impact ionization cross section of the molecular ions H2+, N2+, O2+, CD+, CO+, CO2+, H3O+, and CH4+ for which experimental data have been reported . Where available, we also compare our calculated cross sections with calculated cross sections using the BEB method of Kim and co-workers. The level of agreement between the experimentally determined and calculated cross section is satisfactory in some cases. In all cases, the calculated cross sections exceed the measured cross sections which is not surprising in view of the experimental complications in measuring ionization cross sections of molecular ions due to the presence of competing channels such as ionization dissociative ionization, and dissociative excitation. Work supported in part by FWF, OEAW, and NASA.

  3. Calculation of total and ionization cross sections for electron scattering by primary benzene compounds

    Science.gov (United States)

    Singh, Suvam; Naghma, Rahla; Kaur, Jaspreet; Antony, Bobby

    2016-07-01

    The total and ionization cross sections for electron scattering by benzene, halobenzenes, toluene, aniline, and phenol are reported over a wide energy domain. The multi-scattering centre spherical complex optical potential method has been employed to find the total elastic and inelastic cross sections. The total ionization cross section is estimated from total inelastic cross section using the complex scattering potential-ionization contribution method. In the present article, the first theoretical calculations for electron impact total and ionization cross section have been performed for most of the targets having numerous practical applications. A reasonable agreement is obtained compared to existing experimental observations for all the targets reported here, especially for the total cross section.

  4. Calculation of total and ionization cross sections for electron scattering by primary benzene compounds

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Suvam; Naghma, Rahla; Kaur, Jaspreet; Antony, Bobby, E-mail: bka.ism@gmail.com [Atomic and Molecular Physics Lab, Department of Applied Physics, Indian School of Mines, Dhanbad (India)

    2016-07-21

    The total and ionization cross sections for electron scattering by benzene, halobenzenes, toluene, aniline, and phenol are reported over a wide energy domain. The multi-scattering centre spherical complex optical potential method has been employed to find the total elastic and inelastic cross sections. The total ionization cross section is estimated from total inelastic cross section using the complex scattering potential-ionization contribution method. In the present article, the first theoretical calculations for electron impact total and ionization cross section have been performed for most of the targets having numerous practical applications. A reasonable agreement is obtained compared to existing experimental observations for all the targets reported here, especially for the total cross section.

  5. Pressure of a partially ionized hydrogen gas: numerical results from exact low temperature expansions

    Energy Technology Data Exchange (ETDEWEB)

    Alastuey, A. [Laboratoire de Physique, ENS Lyon, CNRS, Lyon (France); Ballenegger, V. [Institut UTINAM, Universite de Franche-Comte, CNRS, Besancon (France)

    2010-01-15

    We consider a partially ionized hydrogen gas at low densities, where it reduces almost to an ideal mixture made with hydrogen atoms in their ground-state, ionized protons and ionized electrons. By performing systematic low-temperature expansions within the physical picture, in which the system is described as a quantum electron-proton plasma interacting via the Coulomb potential, exact formulae for the first.ve leading corrections to the ideal Saha equation of state have been derived[A. Alastuey, V. Ballenegger et al., J. Stat. Phys. 130, 1119 (2008)]. Those corrections account for all effects of interactions and thermal excitations up to order exp(E{sub H} /kT) included, where E{sub H} {approx_equal} -13.6 eV is the ground state energy of the hydrogen atom. Among the.ve leading corrections, three are easy to evaluate, while the remaining ones involve suitably truncated internal partition functions of H{sub 2} molecules and H{sup -} and H{sub 2}{sup +} ions, for which no analytical formulae are available in closed form. We estimate those partitions functions at.nite temperature via a simple phenomenology based on known values of rotational and vibrational energies. This allows us to compute numerically the leading deviations to the Saha pressure along several isotherms and isochores. Our values are compared with those of the OPAL tables (for pure hydrogen) calculated within the ACTEX method (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Process and device for the polymerization and/or cross-linking by ionizing radiations of a resin component of a composite material part

    International Nuclear Information System (INIS)

    Beziers, D.

    1985-01-01

    An electron beam is directed on a target for the production of X-rays with adequate dose for resin cross-linking. Means are provided for relative motion between ionizing radiations and the irradiated object for partial or total exposure to radiations. The part can be polymerized by electron-beam or X-rays in function of its thickness [fr

  7. Shear flow instability in a partially-ionized plasma sheath around a fast-moving vehicle

    International Nuclear Information System (INIS)

    Sotnikov, V. I.; Mudaliar, S.; Genoni, T. C.; Rose, D. V.; Oliver, B. V.; Mehlhorn, T. A.

    2011-01-01

    The stability of ion acoustic waves in a sheared-flow, partially-ionized compressible plasma sheath around a fast-moving vehicle in the upper atmosphere, is described and evaluated for different flow profiles. In a compressible plasma with shear flow, instability occurs for any velocity profile, not just for profiles with an inflection point. A second-order differential equation for the electrostatic potential of excited ion acoustic waves in the presence of electron and ion collisions with neutrals is derived and solved numerically using a shooting method with boundary conditions appropriate for a finite thickness sheath in contact with the vehicle. We consider three different velocity flow profiles and find that in all cases that neutral collisions can completely suppress the instability.

  8. Study on the electromagnetic waves propagation characteristics in partially ionized plasma slabs

    Directory of Open Access Journals (Sweden)

    Zhi-Bin Wang

    2016-05-01

    Full Text Available Propagation characteristics of electromagnetic (EM waves in partially ionized plasma slabs are studied in this paper. Such features are significant to applications in plasma antennas, blackout of re-entry flying vehicles, wave energy injection to plasmas, and etc. We in this paper developed a theoretical model of EM wave propagation perpendicular to a plasma slab with a one-dimensional density inhomogeneity along propagation direction to investigate essential characteristics of EM wave propagation in nonuniform plasmas. Particularly, the EM wave propagation in sub-wavelength plasma slabs, where the geometric optics approximation fails, is studied and in comparison with thicker slabs where the geometric optics approximation applies. The influences of both plasma and collisional frequencies, as well as the width of the plasma slab, on the EM wave propagation characteristics are discussed. The results can help the further understanding of propagation behaviours of EM waves in nonuniform plasma, and applications of the interactions between EM waves and plasmas.

  9. A consistent model for the equilibrium thermodynamic functions of partially ionized flibe plasma with Coulomb corrections

    International Nuclear Information System (INIS)

    Zaghloul, Mofreh R.

    2003-01-01

    Flibe (2LiF-BeF2) is a molten salt that has been chosen as the coolant and breeding material in many design studies of the inertial confinement fusion (ICF) chamber. Flibe plasmas are to be generated in the ICF chamber in a wide range of temperatures and densities. These plasmas are more complex than the plasma of any single chemical species. Nevertheless, the composition and thermodynamic properties of the resulting flibe plasmas are needed for the gas dynamics calculations and the determination of other design parameters in the ICF chamber. In this paper, a simple consistent model for determining the detailed plasma composition and thermodynamic functions of high-temperature, fully dissociated and partially ionized flibe gas is presented and used to calculate different thermodynamic properties of interest to fusion applications. The computed properties include the average ionization state; kinetic pressure; internal energy; specific heats; adiabatic exponent, as well as the sound speed. The presented results are computed under the assumptions of local thermodynamic equilibrium (LTE) and electro-neutrality. A criterion for the validity of the LTE assumption is presented and applied to the computed results. Other attempts in the literature are assessed with their implied inaccuracies pointed out and discussed

  10. A partially ionized plasma modeling; Un modele de plasma partiellement ionise

    Energy Technology Data Exchange (ETDEWEB)

    Le Thanh, K.C.; Raviart, P.A

    2003-07-01

    We propose a model for the partially ionized plasma sheaths near the anode of an anodic spot electric arc where the cathode is considered as an electron emitter. A fluid description takes into account the heating and the ionization of the plasma induced by the electron beam. As physical hypothesis we assume that the condition of charge neutrality is valid. According that the electron mass can be neglected compared to the ion mass, we can assume that ions and atoms have the same velocity and the same temperature. Electrons and heavy particles are then regarded as two separate fluids coexisting in the plasma. Governing equations are then multi-fluid equations with relaxation correction to the local thermodynamic equilibrium (LTE) and heating by Joule effect. Equations are solved by an operator splitting procedure. That is we first discretize the homogeneous conservation laws (i.e. without source terms) by a finite volume method. The second step is to solve the ordinary differential system (i.e, governing equation without transport terms) with an implicit scheme. (authors)

  11. Oscillator strength of partially ionized high-Z atom on Hartree-Fock Slater model

    International Nuclear Information System (INIS)

    Nakamura, S.; Nishikawa, T.; Takabe, H.; Mima, K.

    1991-01-01

    The Hartree-Fock Slater (HFS) model has been solved for the partially ionized gold ions generated when an intense laser light is irradiated on a gold foil target. The resultant energy levels are compared with those obtained by a simple screened hydrogenic model with l-splitting effect (SHML). It is shown that the energy levels are poorly model by SHML as the ionization level becomes higher. The resultant wave functions are used to evaluate oscillator strength of important line radiations and compared with those obtained by a simple model using hydrogenic wave functions. Its demonstrated that oscillator strength of the 4p-4d and 4d-4f lines are well modeled by the simple method, while the 4-5 transitions such as 4f-5g, 4d-5f, 4p-5d, and 4f-5p forming the so-called N-band emission are poorly modeled and HFS results less strong line emissions. (author)

  12. INJECTION TO RAPID DIFFUSIVE SHOCK ACCELERATION AT PERPENDICULAR SHOCKS IN PARTIALLY IONIZED PLASMAS

    Energy Technology Data Exchange (ETDEWEB)

    Ohira, Yutaka, E-mail: ohira@phys.aoyama.ac.jp [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara 252-5258 (Japan)

    2016-08-10

    We present a three-dimensional hybrid simulation of a collisionless perpendicular shock in a partially ionized plasma for the first time. In this simulation, the shock velocity and upstream ionization fraction are v {sub sh} ≈ 1333 km s{sup −1} and f {sub i} ∼ 0.5, which are typical values for isolated young supernova remnants (SNRs) in the interstellar medium. We confirm previous two-dimensional simulation results showing that downstream hydrogen atoms leak into the upstream region and are accelerated by the pickup process in the upstream region, and large magnetic field fluctuations are generated both in the upstream and downstream regions. In addition, we find that the magnetic field fluctuations have three-dimensional structures and the leaking hydrogen atoms are injected into the diffusive shock acceleration (DSA) at the perpendicular shock after the pickup process. The observed DSA can be interpreted as shock drift acceleration with scattering. In this simulation, particles are accelerated to v ∼ 100 v {sub sh} ∼ 0.3 c within ∼100 gyroperiods. The acceleration timescale is faster than that of DSA in parallel shocks. Our simulation results suggest that SNRs can accelerate cosmic rays to 10{sup 15.5} eV (the knee) during the Sedov phase.

  13. Ionizing feedback from massive stars in massive clusters - III. Disruption of partially unbound clouds

    Science.gov (United States)

    Dale, J. E.; Ercolano, B.; Bonnell, I. A.

    2013-03-01

    We extend our previous smoothed particle hydrodynamics parameter study of the effects of photoionization from O-stars on star-forming clouds to include initially unbound clouds. We generate a set of model clouds in the mass range 104-106 M⊙ with initial virial ratios Ekin/Epot = 2.3, allow them to form stars and study the impact of the photoionizing radiation produced by the massive stars. We find that, on the 3 Myr time-scale before supernovae are expected to begin detonating, the fraction of mass expelled by ionizing feedback is a very strong function of the cloud escape velocities. High-mass clouds are largely unaffected dynamically, while low-mass clouds have large fractions of their gas reserves expelled on this time-scale. However, the fractions of stellar mass unbound are modest and significant portions of the unbound stars are so only because the clouds themselves are initially partially unbound. We find that ionization is much more able to create well-cleared bubbles in the unbound clouds, owing to their intrinsic expansion, but that the presence of such bubbles does not necessarily indicate that a given cloud has been strongly influenced by feedback. We also find, in common with the bound clouds from our earlier work, that many of the systems simulated here are highly porous to photons and supernova ejecta, and that most of them will likely survive their first supernova explosions.

  14. Electron-impact ionization of SiCl{sub 3} using an improved crossed fast-neutral-beam - electron-beam apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, J M; Gutkin, M V; Tarnovsky, V; Becker, K [Department of Physics and Engineering Physics, Stevens Institute of Technology, Hoboken, NJ 07030 (United States)], E-mail: kbecker@poly.edu

    2008-05-15

    The fast-neutral-beam technique is a versatile approach to the determination of absolute cross sections for electron-impact ionization of atoms, stable molecules as well as free radicals and metastable species. A fast neutral beam of the species under study is prepared by charge-transfer neutralization of a mass-selected ion beam and the species are subsequently ionized by an electron beam. Mass- and energy-dispersive selection separates singly from multiply charged ions and parent from fragment ions and allows the determination of partial ionization cross sections. Here we describe some major improvements that were made recently to the fast-beam apparatus that has been used extensively for ionization cross section measurements for the past 15 years in our group. Experiments using well-established ionization cross sections in conjunction with extensive ion trajectory simulations were carried out to test the satisfactory performance of the modified fast-neutral-beam apparatus. We also report absolute partial cross sections for the formation of various singly charged positive ions produced by electron impact on SiCl{sub 3} for impact energies from threshold to 200 eV in the modified fast-beam apparatus.

  15. Partial wave analysis for folded differential cross sections

    Science.gov (United States)

    Machacek, J. R.; McEachran, R. P.

    2018-03-01

    The value of modified effective range theory (MERT) and the connection between differential cross sections and phase shifts in low-energy electron scattering has long been recognized. Recent experimental techniques involving magnetically confined beams have introduced the concept of folded differential cross sections (FDCS) where the forward (θ ≤ π/2) and backward scattered (θ ≥ π/2) projectiles are unresolved, that is the value measured at the angle θ is the sum of the signal for particles scattered into the angles θ and π - θ. We have developed an alternative approach to MERT in order to analyse low-energy folded differential cross sections for positrons and electrons. This results in a simplified expression for the FDCS when it is expressed in terms of partial waves and thereby enables one to extract the first few phase shifts from a fit to an experimental FDCS at low energies. Thus, this method predicts forward and backward angle scattering (0 to π) using only experimental FDCS data and can be used to determine the total elastic cross section solely from experimental results at low-energy, which are limited in angular range.

  16. Cross section determination for the higher ionization of rare gas ions by electron collisions

    International Nuclear Information System (INIS)

    Becker, R.; Frodl, R.; Klein, H.; Schmidt, W.; Clausnitzer, G.; Klinger, H.; Mueller, A.; Salzborn, E.; Fuchs, G.; Viehboeck, F.

    1975-01-01

    The higher ionization of rare gas ions is reported on, which were excited by an electron beam using a crossed-beam technique. A detector for the identification of metastable excited rare gas ions was developed. (WL) [de

  17. Partial radiative recombination cross sections for excited states of hydrogen

    International Nuclear Information System (INIS)

    Fazio, P.M.

    1984-01-01

    In calculating the radiative recombination cross sections for interstellar H II regions, usually only the electric dipole term in the expansion of the interaction Hamiltonian is kept. The dipole and quadrupole transition strengths in closed analytical form are calculated here using the Coulomb wave functions because results for any electron energy and for recombination into any angular momentum state of hydrogen are needed. Several interesting effects are found. First, the transition probabilities are maximum for recombination into specific intermediate angular momentum states at low energies (w < 2eV) and where the free state angular momentum is greater than that of the bound state. Further, that specific intermediate angular momentum state depends on the kinetic energy of the free electron. This behavior is in contrast to the normal behavior of the transition strengths where recombination into s states is greatest and decreases with increasing angular momentum. Second, the quadrupole matrix elements vanish for certain velocities of the free electron. This leads to minima in the corresponding quadrupole cross sections when plotted as a function of the free electron's kinetic energy. Finally, the partial cross sections for highly excited states are greater than previously calculated because of the additional effects of the quadrupole transitions

  18. Threshold law for ionization cross sections in the Temkin-Poet model

    International Nuclear Information System (INIS)

    Macek, J.H.; Ihra, W.

    1997-01-01

    An integral representation of wave functions for the Temkin-Poet model of electron impact on atomic hydrogen is given. Approximate wave functions are evaluated analytically for large hyperradius to extract the ionization S-matrix element. An ionization cross section of the form exp[-aE -1/6 +bE 1/6 ], where a and b are positive constants, is derived. The exponential suppression of ionization for small E appears to be the quantum counterpart of the delayed onset of ionization in the classical theory for this model. copyright 1997 The American Physical Society

  19. The Physics of Partially Ionized Gas with Applications to Processes in the Interstellar Medium

    International Nuclear Information System (INIS)

    Greenfield, E. J.; Jokipii, J. R.; Giacalone, Joe

    2011-01-01

    The dynamical equations for a partially ionized plasma are a matter of some recent controversy. Understanding this problem is important in understanding the interaction of the interstellar medium with the heliosphere and for understanding the spectrum of interstellar turbulence. If collision scales are much smaller than the internal interaction scales such as the ion gyroradius, the fluid approximation may be used. The analysis then must deal with at least three fluids (protons, electrons, and neutrals) which are coupled to each other by collisions and/or electromagnetic fields. Often, the proton and electron gyro-radii are much smaller than the collision length scales, so the electric and magnetic fields dominate the motions of the electrons and protons. In this case, the only important particle-particle collisions are those of the electrons and protons with the neutral atoms. Since the three species have, in general, different velocities, it is not immediately clear which fluid velocity to use. This ambiguity in the choice of fluid velocity has led to recent confusion regarding the physics of partially ionized plasmas. If the neutrals have a significant fraction of the mass, working in the center-of-mass coordinate frame can result in dynamical equations that differ greatly from those of ideal MHD. This is because the magnetic field is not frozen into the frame moving at the center-of-mass velocity, which leads to additional effects on the magnetic field that can be difficult to understand intuitively. To the extent that the electron mass is negligible, the magnetic field is actually found to be frozen into the frame moving with the electron bulk velocity. If we then take U to be the bulk velocity of the proton fluid the resulting dynamical equations closely resemble those of ideal MHD with the exception of the Hall term in the induction equation. Similarly, the frequently used Cowling conductivity also depends on the choice of coordinate frame. These conclusions

  20. Electron ionization of open/closed chain isocarbonic molecules relevant in plasma processing: Theoretical cross sections

    International Nuclear Information System (INIS)

    Patel, Umang R.; Joshipura, K. N.; Pandya, Siddharth H.; Kothari, Harshit N.

    2014-01-01

    In this paper, we report theoretical electron impact ionization cross sections from threshold to 2000 eV for isocarbonic open chain molecules C 4 H 6 , C 4 H 8 , C 4 F 6 including their isomers, and closed chain molecules c-C 4 H 8 and c-C 4 F 8 . Theoretical formalism employed presently, viz., Complex Scattering Potential-ionization contribution method has been used successfully for a variety of polyatomic molecules. The present ionization calculations are very important since results available for the studied targets are either scarce or none. Our work affords comparison of C 4 containing hydrocarbon versus fluorocarbon molecules. Comparisons of the present ionization cross sections are made wherever possible, and new ionization data are also presented

  1. Ionization

    International Nuclear Information System (INIS)

    2002-01-01

    This document reprints the text of the French by-law from January 8, 2002 relative to the approval and to the controls and verifications of facilities devoted to the ionizing of food products for human beings and animals. The by-law imposes the operators of such facilities to perform measurements and dosimetric verifications all along the ionization process. (J.S.)

  2. Energy and angle differential cross sections for the electron-impact double ionization of helium

    International Nuclear Information System (INIS)

    Colgan, James P.; Pindzola, M.S.; Robicheaux, F.

    2008-01-01

    Energy and angle differential cross sections for the electron-impact double ionization of helium are calculated using a non-perturbative time-dependent close-coupling method. Collision probabilities are found by projection of a time evolved nine dimensional coordinate space wave function onto fully antisymmetric products of spatial and spin functions representing three outgoing Coulomb waves. At an incident energy of 106 eV, we present double energy differential cross sections and pentuple energy and angle differential cross sections. The pentuple energy and angle differential cross sections are found to be in relative agreement with the shapes observed in recent (e,3e) reaction microscope experiments. Integration of the differential cross sections over all energies and angles yields a total ionization cross section that is also in reasonable agreement with absolute crossed-beams experiments.

  3. Molecular data for a biochemical model of DNA damage: Electron impact ionization and dissociative ionization cross sections of DNA bases and sugar-phosphate backbone

    International Nuclear Information System (INIS)

    Huo, Winifred M.; Dateo, Christopher E.; Fletcher, Graham D.

    2006-01-01

    As part of the database for building up a biochemical model of DNA radiation damage, electron impact ionization cross sections of sugar-phosphate backbone and DNA bases have been calculated using the improved binary-encounter dipole (iBED) model. It is found that the total ionization cross sections of C 3 ' - and C 5 ' -deoxyribose-phosphate, two conformers of the sugar-phosphate backbone, are close to each other. Furthermore, the sum of the ionization cross sections of the separate deoxyribose and phosphate fragments is in close agreement with the C 3 ' - and C 5 ' -deoxyribose-phosphate cross sections, differing by less than 10%, an indication that a building-up principle may be applicable. Of the four DNA bases, the ionization cross section of guanine is the largest, then in decreasing order, adenine, thymine, and cytosine. The order is in accordance with the known propensity of oxidation of the bases by ionizing radiation. Dissociative ionization (DI), a process that both ionizes and dissociates a molecule, is investigated for cytosine. The DI cross section for the formation of H and (cytosine-H1) + , with the cytosine ion losing H at the 1 position, is also reported. The threshold of this process is calculated to be 16.9eV. Detailed analysis of ionization products such as in DI is important to trace the sequential steps in the biochemical process of DNA damage

  4. A data acquisition system for measuring ionization cross section in laser multi-step resonant ionization experiment

    International Nuclear Information System (INIS)

    Qian Dongbin; Guo Yuhui; Zhang Dacheng; Chinese Academy of Sciences, Beijing; Ma Xinwen; Zhao Zhizheng; Wang Yanyu; Zu Kailing

    2006-01-01

    A CAMAC data acquisition system for measuring ionization cross section in laser multi-step resonant ionization experiment is described. The number of scalers in the front-end CAMAC can be adjusted by changing the data read-out table files. Both continuous and manual acquisition models are available, and there is a wide adjustable range from 1 ms to 800 s with the acquisition time unit. The long-term stability, Δt/t, for the data acquisition system with an acquisition time unit of 100 s was measured to be better than ±0.01%, thus validating its reliability in long-term online experimental data acquisition. The time response curves for three electrothermal power-meters were also measured by this DAQ system. (authors)

  5. Multi-fluid Approach to High-frequency Waves in Plasmas. II. Small-amplitude Regime in Partially Ionized Media

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Gómez, David; Soler, Roberto; Terradas, Jaume, E-mail: david.martinez@uib.es [Departament de Física, Universitat de les Illes Balears, E-07122, Palma de Mallorca (Spain)

    2017-03-01

    The presence of neutral species in a plasma has been shown to greatly affect the properties of magnetohydrodynamic waves. For instance, the interaction between ions and neutrals through momentum transfer collisions causes the damping of Alfvén waves and alters their oscillation frequency and phase speed. When the collision frequencies are larger than the frequency of the waves, single-fluid magnetohydrodynamic approximations can accurately describe the effects of partial ionization, since there is a strong coupling between the various species. However, at higher frequencies, the single-fluid models are not applicable and more complex approaches are required. Here, we use a five-fluid model with three ionized and two neutral components, which takes into consideration Hall’s current and Ohm’s diffusion in addition to the friction due to collisions between different species. We apply our model to plasmas composed of hydrogen and helium, and allow the ionization degree to be arbitrary. By analyzing the corresponding dispersion relation and numerical simulations, we study the properties of small-amplitude perturbations. We discuss the effect of momentum transfer collisions on the ion-cyclotron resonances and compare the importance of magnetic resistivity, and ion–neutral and ion–ion collisions on the wave damping at various frequency ranges. Applications to partially ionized plasmas of the solar atmosphere are performed.

  6. Measurement of 18O + 10B fusion cross section and construction of a position sensitive ionization chamber

    International Nuclear Information System (INIS)

    Added, N.

    1987-01-01

    The 18 O + 10 B fusion reaction has been investigated within the bombarding energy range of 29,0 MeV lab 0 lab 0 angular range. For this purpose, a high resolution position sensitive ionization chamber has been developed and constructed. Experimental results compared to model predictions and experimental systematics found in the literature allows to reject compound nucleus limitation to the fusion cross section up to energies as high as five times the coulomb barrier. Statistical model fits to the residues elementary distributions reveal a quite difuse partial fusion cross section in the angular momentum space. Systematic analysis of fusion barrier height (V B ) and radius (R B ) for neighbouring nuclei point out the importance of the nuclear matter difuseness in the competition between the fusion and quasi-direct process. Calculations within this framework were performed. (author) [pt

  7. Isoelectronic sequence fits to configuration-averaged photoionization cross sections and ionization energies

    International Nuclear Information System (INIS)

    Clark, R.E.H.; Cowan, R.D.; Bobrowicz, F.W.

    1986-01-01

    Hartree--Fock wave functions have been used to calculate configuration -averaged photoionization cross sections and ionization energies for orbitals 1s< or =nl< or =5g in He-like through Al-like isoelectroni csequences. The photoionization cross sections have been fitted as a function of the nuclear charge, Z, and photon energy, X, in threshold units, with average error of less than 10%. The ionization energies have been fitted as a function of Z with errors of less than 0.5%

  8. Calculation of the differential cross sections of excitation and ionization of a helium atom by electrons

    International Nuclear Information System (INIS)

    Demkin, V.P.; Pecheritsyn, A.A.

    1995-01-01

    Equations for the amplitudes and differential cross sections of electronic excitation and ionization of a helium atom are derived in the approximation of a open-quotes frozenclose quotes ion core. The wave functions of the discrete states are chosen in the form of generalized hydrogenlike orbitals. The radial wave functions of the continuous spectrum are determined by solving the equation of motion numerically. The differential excitation cross sections of excitation of the 2p, 3p, and 4p levels and ionization of a helium atom by electrons are calculated in the energy range up to 50 eV. Estimates are obtained for the nonorthogonal wave functions in the amplitudes of the excitation and ionization processes. It is shown that the given method is more compatible with experiment than the Born method

  9. Hartree--Slater calculation of the cross section for L-shell ionization of argon by simple heavy charged particles

    International Nuclear Information System (INIS)

    Choi, B.

    1975-01-01

    The cross sections for L-shell and subshell ionization by direct Coulomb excitation of argon by incident heavy charged particles are evaluated. Incident particles are described in the plane-wave Born approximation, and nonrelativistic Hartree-Slater (HS) wave functions are used for the atomic electrons. Form factors, energy distributions, and ionization cross sections are compared with those obtained from screened hydrogenic wave functions. At most incident energies, the HS results for the total ionization cross section are only slightly smaller than those obtained with screened hydrogenic wave functions, but considerable discrepancies are found for form factors and energy distributions near the ionization threshold

  10. Elastic, excitation, ionization and charge transfer cross sections of current interest in fusion energy research

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, D.R.; Krstic, P.S. [Oak Ridge National Lab. TN (United States). Physics Div.

    1997-01-01

    Due to the present interest in modeling and diagnosing the edge and divertor plasma regions in magnetically confined fusion devices, we have sought to provide new calculations regarding the elastic, excitation, ionization, and charge transfer cross sections in collisions among relevant ions, neutrals, and isotopes in the low-to intermediate-energy regime. We summarize here some of our recent work. (author)

  11. 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.

  12. Electron impact ionization of B-like ion N2+. Resonance enhancement of the single-channel cross section

    International Nuclear Information System (INIS)

    Li Guohe; Qian Xingzhong; Pan Soufu

    1998-01-01

    The electron impact ionization cross sections of B-like ion N 2+ are calculated in the Coulomb-Born no exchange approximation by using R-matrix method, and the single differential cross section is given. The calculated results exhibit the Rydberg series of resonances. The resonance enhancement of the single-channel cross section is significantly greater than direct ionization cross section. It is agreement with that of Chidichimo

  13. Collision effects on propagation characteristics of electromagnetic waves in a sub-wavelength plasma slab of partially ionized dense plasmas

    Science.gov (United States)

    Bowen, LI; Zhibin, WANG; Qiuyue, NIE; Xiaogang, WANG; Fanrong, KONG; Zhenyu, WANG

    2018-01-01

    Intensive collisions between electrons and neutral particles in partially ionized plasmas generated in atmospheric/sub-atmospheric pressure environments can sufficiently affect the propagation characteristics of electromagnetic waves, particularly in the sub-wavelength regime. To investigate the collisional effect in such plasmas, we introduce a simplified plasma slab model with a thickness on the order of the wavelength of the incident electromagnetic wave. The scattering matrix method (SMM) is applied to solve the wave equation in the plasma slab with significant nonuniformity. Results show that the collisions between the electrons and the neutral particles, as well as the incident angle and the plasma thickness, can disturb the transmission and reduce reflection significantly.

  14. Effects of dust-charge fluctuations on the potential of an array of projectiles in a partially ionized dusty plasma

    International Nuclear Information System (INIS)

    Ali, S.; Nasim, M.H.; Murtaza, G.

    2003-01-01

    The expressions for the Debye and the wake potential are derived by incorporating dust-charge fluctuations of a single projectile, as well as of an array of dust grain projectiles, propagating through a partially ionized dusty plasma with a constant velocity. Numerically, the effects of the dust-charge fluctuations and the dust-neutral collisions on the electrostatic potential for a single, three, six and ten projectiles are examined. The dust-charge relaxation rate modifies the shape of the Debye as well as the wake potential. For smaller values of the relaxation rates a potential well is formed instead of Debye potential

  15. Bias-induced migration of ionized donors in amorphous oxide semiconductor thin-film transistors with full bottom-gate and partial top-gate structures

    Directory of Open Access Journals (Sweden)

    Mallory Mativenga

    2012-09-01

    Full Text Available Bias-induced charge migration in amorphous oxide semiconductor thin-film transistors (TFTs confirmed by overshoots of mobility after bias stressing dual gated TFTs is presented. The overshoots in mobility are reversible and only occur in TFTs with a full bottom-gate (covers the whole channel and partial top-gate (covers only a portion of the channel, indicating a bias-induced uneven distribution of ionized donors: Ionized donors migrate towards the region of the channel that is located underneath the partial top-gate and the decrease in the density of ionized donors in the uncovered portion results in the reversible increase in mobility.

  16. Partial dissociative emission cross sections and product state distributions of the resulting photofragments

    Energy Technology Data Exchange (ETDEWEB)

    Picconi, David; Grebenshchikov, Sergy Yu., E-mail: Sergy.Grebenshchikov@ch.tum.de

    2016-12-20

    This paper relates the partial cross section of a continuous optical emission into a given scattering channel of the lower electronic state to the photofragment population. This allows one to infer partial emission cross sections ‘non-optically’ from product state distributions; in computations, explicit construction of exact scattering states is therefore avoided. Applications to the emission spectra of NaI, CO{sub 2}, and pyrrole are given. It is also demonstrated that a similar relationship holds between partial cross sections of dissociative photoionization and distributions of ionic fragments over final product channels.

  17. Mirroring behavior of partial photodetachment and photoionization cross sections in the neighborhood of a resonance

    International Nuclear Information System (INIS)

    Liu, C.; Starace, A.F.

    1999-01-01

    Partial photodetachment and photoionization cross sections corresponding to highly excited residual atoms or ions are shown analytically to mirror one another in the neighborhood of a resonance. More precisely, any two groupings of partial cross sections are shown here to have components whose variations with energy near a resonance are equal in magnitude and opposite in direction. This work extends an analysis of Starace [Phys. Rev. A 16, 231 (1977)] for the behavior of partial cross sections near a resonance to the case when the ρ 2 parameter of Fano and Cooper [Phys. Rev. 137, A1364 (1965)] tends to zero. copyright 1999 The American Physical Society

  18. Mirroring behavior of partial photodetachment and photoionization cross sections in the neighborhood of a resonance

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.; Starace, A.F. [Department of Physics and Astronomy, The University of Nebraska, Lincoln, Nebraska 68588-0111 (United States)

    1999-03-01

    Partial photodetachment and photoionization cross sections corresponding to highly excited residual atoms or ions are shown analytically to mirror one another in the neighborhood of a resonance. More precisely, any two groupings of partial cross sections are shown here to have components whose variations with energy near a resonance are equal in magnitude and opposite in direction. This work extends an analysis of Starace [Phys. Rev. A {bold 16}, 231 (1977)] for the behavior of partial cross sections near a resonance to the case when the {rho}{sup 2} parameter of Fano and Cooper [Phys. Rev. {bold 137}, A1364 (1965)] tends to zero. {copyright} {ital 1999} {ital The American Physical Society}

  19. Theoretical calculation of fully differential cross sections for electron-impact ionization of hydrogen molecules

    International Nuclear Information System (INIS)

    Gao Junfang; Madison, D H; Peacher, J L

    2006-01-01

    We have recently proposed the orientation averaged molecular orbital (OAMO) approximation for calculating fully differential cross sections (FDCS) for electron-impact ionization of molecules averaged over all molecular orientations. Orientation averaged FDCS were calculated for electron-impact ionization of nitrogen molecules using the distorted wave impulse approximation (DWIA) and the molecular three-body distorted wave (M3DW) approximation. In this paper, we use the same methods to examine the FDCS for ionization of hydrogen molecules. It is found that the DWIA yields reasonable results for high-energy incident electrons. While the DWIA breaks down for low-energy electrons, the M3DW gives reasonable results down to incident-electron energies around 35 eV

  20. The temporal behaviour of MHD waves in a partially ionized prominence-like plasma: Effect of heating and cooling

    Science.gov (United States)

    Ballester, J. L.; Carbonell, M.; Soler, R.; Terradas, J.

    2018-01-01

    Context. During heating or cooling processes in prominences, the plasma microscopic parameters are modified due to the change of temperature and ionization degree. Furthermore, if waves are excited on this non-stationary plasma, the changing physical conditions of the plasma also affect wave dynamics. Aims: Our aim is to study how temporal variation of temperature and microscopic plasma parameters modify the behaviour of magnetohydrodynamic (MHD) waves excited in a prominence-like hydrogen plasma. Methods: Assuming optically thin radiation, a constant external heating, the full expression of specific internal energy, and a suitable energy equation, we have derived the profiles for the temporal variation of the background temperature. We have computed the variation of the ionization degree using a Saha equation, and have linearized the single-fluid MHD equations to study the temporal behaviour of MHD waves. Results: For all the MHD waves considered, the period and damping time become time dependent. In the case of Alfvén waves, the cut-off wavenumbers also become time dependent and the attenuation rate is completely different in a cooling or heating process. In the case of slow waves, while it is difficult to distinguish the slow wave properties in a cooling partially ionized plasma from those in an almost fully ionized plasma, the period and damping time of these waves in both plasmas are completely different when the plasma is heated. The temporal behaviour of the Alfvén and fast wave is very similar in the cooling case, but in the heating case, an important difference appears that is related with the time damping. Conclusions: Our results point out important differences in the behaviour of MHD waves when the plasma is heated or cooled, and show that a correct interpretation of the observed prominence oscillations is very important in order to put accurate constraints on the physical situation of the prominence plasma under study, that is, to perform prominence

  1. Quantum-mechanical predictions of electron-induced ionization cross sections of DNA components

    International Nuclear Information System (INIS)

    Champion, Christophe

    2013-01-01

    Ionization of biomolecules remains still today rarely investigated on both the experimental and the theoretical sides. In this context, the present work appears as one of the first quantum mechanical approaches providing a multi-differential description of the electron-induced ionization process of the main DNA components for impact energies ranging from the target ionization threshold up to about 10 keV. The cross section calculations are here performed within the 1st Born approximation framework in which the ejected electron is described by a Coulomb wave whereas the incident and the scattered electrons are both described by a plane wave. The biological targets of interest, namely, the DNA nucleobases and the sugar-phosphate backbone, are here described by means of the GAUSSIAN 09 system using the restricted Hartree-Fock method with geometry optimization. The theoretical predictions also obtained have shown a reasonable agreement with the experimental total ionization cross sections while huge discrepancies have been pointed out with existing theoretical models, mainly developed within a semi-classical framework.

  2. Review of experimental cross sections for K-shell ionization by light ions

    International Nuclear Information System (INIS)

    Paul, H.; Muhr, J.

    1986-01-01

    We review experimental K-shell ionization cross sections using a data file containing about 7800 total X-ray or Auger production cross sections taken from the literature for which Z 1 /Z 2 1 and Z 2 are the atomic numbers of projectile and target. We compare various recent collections of K-shell fluorescence yields ω, and we use Krause's tables to convert the data to ionization cross sections. For every projectile, we normalize these data using the theoretical cross section due to Brandt and Lapicki (ECPSSR). We show them plotted versus log xi (where xi is the scaled projectile velocity) in the appendix, and we average them in equal intervals Δ log xi. A statistical criterion is used to exclude references with discrepant data. We find that the average normalized cross section anti s is mostly close to unity (i.e., ECPSSR describes the data well), but that there are also significant deviations at certain values of xi. For almost all projectiles, anti s decreases below unity for log xi 2 for small and for large log xi. We approximate anti s by analytical functions of log xi and thus produce ''reference'' cross sections for selected proton energies and targets. For heavier projectiles (and also for protons on light targets), additional systematic deviations develop: a maximum of anti s around log xi=-0.6 and a minimum around log xi=-0.3. Above log xi=-0.1, the influence of multiple ionization and of electron capture by the projectile becomes noticeable with increasing Z 1 . X-ray cross sections for light solid or gaseous targets (Z 2 2 >5). (orig.)

  3. Electron-impact excitation and ionization cross sections for ground state and excited helium atoms

    International Nuclear Information System (INIS)

    Ralchenko, Yu.; Janev, R.K.; Kato, T.; Fursa, D.V.; Bray, I.; Heer, F.J. de

    2008-01-01

    Comprehensive and critically assessed cross sections for the electron-impact excitation and ionization of ground state and excited helium atoms are presented. All states (atomic terms) with n≤4 are treated individually, while the states with n≥5 are considered degenerate. For the processes involving transitions to and from n≥5 levels, suitable cross section scaling relations are presented. For a large number of transitions, from both ground and excited states, convergent close coupling calculations were performed to achieve a high accuracy of the data. The evaluated/recommended cross section data are presented by analytic fit functions, which preserve the correct asymptotic behavior of the cross sections. The cross sections are also displayed in graphical form

  4. Fully differential cross sections for low to intermediate energy perpendicular plane ionization of xenon atoms

    Energy Technology Data Exchange (ETDEWEB)

    Purohit, G., E-mail: ghanshyam.purohit@spsu.ac.in; Singh, P.; Patidar, V.

    2014-12-15

    Highlights: • We present triply differential cross section (TDCS) results for the perpendicular plane ionization of xenon atoms. • The TDCS has been calculated in the modified distorted wave Born approximation formalism. • The effects of target polarization and post collision interaction have also been included. • The polarization potential, higher order effects and PCI has been found to be useful in the description of TDCS. - Abstract: Triple differential cross section (TDCS) results are reported for the perpendicular plane ionization of Xe (5p) at incident electron energies 5 eV, 10 eV, 20 eV, and 40 eV above ionization potential. The modified distorted wave Born approximation formalism with first as well as the second order Born terms has been used to calculate the TDCS. Effects of target polarization and post collision interaction have also been included. We compare the (e, 2e) TDCS results of our calculation with the recent available experimental data and theoretical results and discuss the process contributing to structure seen in the differential cross section. It has been observed from the present study that the second order effect and target polarization make significant contribution in description of collision dynamics of xenon at the low and intermediate energy for the perpendicular emission of electrons.

  5. Double- and triple-differential cross sections for electron-impact ionization of helium

    International Nuclear Information System (INIS)

    Biswas, R.; Sinha, C.

    1995-01-01

    Triple- (TDCS) and double- (DDCS) differential cross sections have been calculated for single ionization in electron-helium collisions for asymmetric geometry at intermediate and medium high energies. The TDCS and DDCS results have been presented for different kinematical situations and have been compared with the corresponding experiments. In the present prescription, the final-state wave function involves the correlation between the two continuum electrons and satisfies the three-body asymptotic boundary condition (for asymmetric geometry), which is an important criterion for reliable ionization cross sections. The sensitivity of the ionization cross sections (particularly of the TDCS) with respect to the choice of the bound-state wave function of the He atom has also been studied, using two different forms of wave function of the He atom. The binary-to-recoil peak intensity ratio against momentum transfer in TDCS is found to be in closer agreement with the experiment for the simple Hylleraas wave function than for the Hartree-Fock wave function. The DDCS results are found to be in good agreement with the experimental data of Mueller-Fiedler et al. [J. Phys. B 19, 1211 (1986)] for lower ejected energy (E 2 ), while for higher E 2 the results are closer to the measurements of Shyn et al. [Phys. Rev. A 19, 557 (1979)] and Avaldi et al. [Nuovo Cimento D 9, 97 (1987)

  6. Fully differential cross sections for low to intermediate energy perpendicular plane ionization of xenon atoms

    International Nuclear Information System (INIS)

    Purohit, G.; Singh, P.; Patidar, V.

    2014-01-01

    Highlights: • We present triply differential cross section (TDCS) results for the perpendicular plane ionization of xenon atoms. • The TDCS has been calculated in the modified distorted wave Born approximation formalism. • The effects of target polarization and post collision interaction have also been included. • The polarization potential, higher order effects and PCI has been found to be useful in the description of TDCS. - Abstract: Triple differential cross section (TDCS) results are reported for the perpendicular plane ionization of Xe (5p) at incident electron energies 5 eV, 10 eV, 20 eV, and 40 eV above ionization potential. The modified distorted wave Born approximation formalism with first as well as the second order Born terms has been used to calculate the TDCS. Effects of target polarization and post collision interaction have also been included. We compare the (e, 2e) TDCS results of our calculation with the recent available experimental data and theoretical results and discuss the process contributing to structure seen in the differential cross section. It has been observed from the present study that the second order effect and target polarization make significant contribution in description of collision dynamics of xenon at the low and intermediate energy for the perpendicular emission of electrons

  7. Ionization of molecules by electron impact: Differential and total cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Rezkallah, Z. [Laboratoire de Physique Quantique et Systemes Dynamiques, Departement de physique, Faculte des sciences, Universite Ferhat Abbas, Setif 19000 (Algeria); Houamer, S., E-mail: hosalim@yahoo.com [Laboratoire de Physique Quantique et Systemes Dynamiques, Departement de physique, Faculte des sciences, Universite Ferhat Abbas, Setif 19000 (Algeria); Dal Cappello, C. [Laboratoire de Physique Moleculaire et des Collisions, Universite Paul Verlaine-Metz, Institut de Physique, 1 Boulevard Arago, 57078 Metz Cedex 3 (France); Charpentier, I. [Laboratoire de Physique et Mecanique des Materiaux, Universite Paul Verlaine-Metz UMR 7554, ile du Saulcy, 57045 Metz Cedex 1 (France); Roy, A.C. [School of Mathematical Sciences, Ramakrishna Mission Vivekananda University, Belur Math 711202, West Bengal (India)

    2011-12-01

    The first Born approximation is applied to calculate differential and total ionization cross sections of a set of small molecules, namely, HF, H{sub 2}O, NH{sub 3} and CH{sub 4} by electron impact. The molecular targets are described by single center molecular orbitals consisting of linear combinations of atomic orbitals (MO-LCAO). First, we have considered electron momentum spectroscopy experiments to check the accuracy of the wave functions. The triply, doubly, singly differential and total cross sections are then evaluated in a systematic way for a variety of kinematics. The results are discussed and compared with experiments.

  8. Doubly differential cross sections for ionization of helium by electron impact

    International Nuclear Information System (INIS)

    Ray, H.; Werner, U.; Roy, A.C.

    1991-01-01

    The Glauber approximation is used to calculate doubly differential cross sections (DDCS's) for electron-impact ionization of helium at incident energies of 100, 300, and 500 eV. Angular dependences of the cross sections are presented for the primary (scattered) electrons. The present calculation is done for the case where the energy of the primary electron is large compared with that of the secondary (ejected) electron. A comparison is made of the present DDCS with the results of other calculations and experiment

  9. Differential cross sections for single ionization of H2 by 75keV proton impact

    International Nuclear Information System (INIS)

    Chowdhury, U; Schulz, M; Madison, D H

    2012-01-01

    We have calculated Triply differential cross sections (TDCS) and doubly differential cross sections (DDCS) for single ionization of H 2 by 75 keV proton impact using the molecular 3 body distorted wave Eikonal initial state (M3DW-EIS) approach. Previously published measured DDCS-P (differential in the projectile scattering angle and integrated over the ejected electron angles) found pronounced structures at relatively large angles which were interpreted as an interference resulting from the two-centered potential of the molecule.

  10. (n, {alpha}) cross section measurement of light nuclei using gridded ionization chamber and gaseous sample

    Energy Technology Data Exchange (ETDEWEB)

    Sanami, Toshiya; Baba, Mamoru; Saito, Keiichiro; Ibara, Yasutaka; Yamazaki, Tetsuro; Sato, Jun; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan)

    1998-03-01

    We have developed a measuring method of (n, {alpha}) cross section by using gaseous sample in a gridded ionization chamber. In this study, we measured the {sup 12}C(n, {alpha}{sub 0}) and the {sup 16}O(n, {alpha}{sub 0}), (n, {alpha}{sub 123}) cross sections for En=11.5 and 12.8 MeV neutrons. We also deduced the {sup 12}C(n, x{alpha}) spectrum and analyzed the data by a kinematic calculation combined with the reaction data of the {sup 12}C(n, n`3{alpha}). (author)

  11. Experimental and theoretical determinations of the absolute ionization cross section of alkali metals by electron impact in the energy range from 100 to 2000 eV

    International Nuclear Information System (INIS)

    Jalin, Rene

    1972-01-01

    The absolute electron impact ionization cross sections for the alkali metals in the energy range between 100 eV and 2000 eV were measured by the non-modulated crossed beam technique. The neutral beam of alkali atoms is produced by a Knudsen cell and crossed at right angles with the electron beam. The ions formed are collected on a plate and their intensity determined with a D.C. amplifier. The neutral beam is condensed on a cold trap cooled with liquid nitrogen, this temperature being much lower than that required to obtain total condensation. The amount of metal deposited is measured by the isotopic dilution technique and by atomic absorption, and the density of the atoms in the neutral beam is calculated. The total absolute ionization cross sections can then be determined. All possible errors have been carefully analyzed and their magnitudes estimated. The absolute ionization cross section for Li at an energy of 500 eV is: Q Li = 0,358 x 10 -16 cm 2 . This value is half of that obtained by Mac Farland and Kinney. The partial ionization cross sections for the singly and multiply charged ions is determined with a mass spectrometer attached to this apparatus. For the singly charged ions, the variation of the cross section with the energy of the ionizing electrons is in agreement with the optically allowed transition law: Q = A log BE/E. From the variation of Q with E, the squared matrix elements of the transition moment (|M i |) 2 are determined for all the elements studied. New calculations of the ionization cross section of Li and Na were performed in the framework of the Born-Bethe approximation as modified by Gaudin and Botter to take into account collisions with large momentum variation of the incident electron. Hartree-Fock type wave functions for the ground state atom (tabulated by Clementi) were used. The calculated values are in good agreement with our experimental results and with the former theoretical results calculated by various methods. This work also

  12. Secondary-electron-production cross sections for electron-impact ionization of helium

    International Nuclear Information System (INIS)

    Goruganthu, R.R.; Bonham, R.A.

    1986-01-01

    Measurements of the double-differential cross sections (DDCS) as a function of the ejected energy, angle, and primary energy for electron-impact ionization of helium are reported at incident energies of 200, 500, 1000, and 2000 eV. The ejection angle is varied from 30 0 to 150 0 in steps of 15 0 . The cross sections were obtained by use of a crossed-beam apparatus with an effusive gas source and a pulsed electron beam. Scattered and ejected electrons were energy analyzed by time-of-flight analysis from 2 eV to the primary energy as a function of the ejection angle. The relative measurements were normalized by matching the experimental elastic differential cross sections to absolute measurements at selected angles. Comparisons of the DDCS with available literature values revealed significant differences. At 2000 eV impact energy, first-Born-approximation calculations of the DDCS were found to be in agreement with the present data for ejected energies between 2 and 40 eV. At large angles and lower incident energies the Born calculation results are lower than the present DDCS. The DDCS were fitted with a Legendre-polynomial expansion as a function of ejection angle for fixed ejected and primary energies. The energy distributions of ejected electrons derived from these fits are presented and used to calculate the total ionization cross section

  13. Inclusive and exclusive cross sections for multiple ionization by fast, highly charged ions in the independent-electron approximation

    International Nuclear Information System (INIS)

    Ben-Itzhak, I.; Gray, T.J.; Legg, J.C.; McGuire, J.H.

    1988-01-01

    Cross sections for the ionization of n of N electrons with equal single-electron ionization probability P are considered. When both N and the projectile charge q are large, the cross sections for single and double ionization are both found to be approximately linear in q at 1 MeVamu. The ratio of double-to-single-ionization cross sections is independent of q. Moreover, first-order perturbation theory for the single-electron ionization probability P, which varies as q 2 , is found to be applicable due to the damping of contributions with large P caused by factors of (1-P)/sup N/ - /sup n/. For large P there are differences between the inclusive probability P and the probability NP commonly used for a target with N electrons. Both of these probabilities differ significantly from the exclusive probability NP(1-P)/sup N/ -1 for the ionization of only one electron. For large N and large q, the exclusive ionization probabilities for removing exactly n of the N electrons tend to be concentrated in somewhat separate ranges of impact parameters b, defining impact-parameter ''windows.'' The windows which we obtain using the quantum-mechanical semiclassical-Coulomb-approximation (SCA) probabilities are similar to those using classical Monte Carlo calculations. Model calculations, based on analytic fits to the SCA probabilities, are used to obtain approximate analytic expressions for single- and double-ionization cross sections and for the impact-parameter windows

  14. COLLISIONLESS SHOCKS IN A PARTIALLY IONIZED MEDIUM. III. EFFICIENT COSMIC RAY ACCELERATION

    Energy Technology Data Exchange (ETDEWEB)

    Morlino, G.; Blasi, P.; Bandiera, R.; Amato, E. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi, 5, I-50125 Firenze (Italy); Caprioli, D. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States)

    2013-05-10

    In this paper, we present the first formulation of the theory of nonlinear particle acceleration in collisionless shocks in the presence of neutral hydrogen in the acceleration region. The dynamical reaction of the accelerated particles, the magnetic field amplification, and the magnetic dynamical effects on the shock are also included. The main new aspect of this study, however, consists of accounting for charge exchange and the ionization of a neutral hydrogen, which profoundly change the structure of the shock, as discussed in our previous work. This important dynamical effect of neutrals is mainly associated with the so-called neutral return flux, namely the return of hot neutrals from the downstream region to upstream, where they deposit energy and momentum through charge exchange and ionization. We also present the self-consistent calculation of Balmer line emission from the shock region and discuss how to use measurements of the anomalous width of the different components of the Balmer line to infer cosmic ray acceleration efficiency in supernova remnants showing Balmer emission: the broad Balmer line, which is due to charge exchange of hydrogen atoms with hot ions downstream of the shock, is shown to become narrower as a result of the energy drainage into cosmic rays, while the narrow Balmer line, due to charge exchange in the cosmic-ray-induced precursor, is shown to become broader. In addition to these two well-known components, the neutral return flux leads to the formation of a third component with an intermediate width: this too contains information on ongoing processes at the shock.

  15. Partial sums of lagged cross-products of AR residuals and a test for white noise

    NARCIS (Netherlands)

    de Gooijer, J.G.

    2008-01-01

    Partial sums of lagged cross-products of AR residuals are defined. By studying the sample paths of these statistics, changes in residual dependence can be detected that might be missed by statistics using only the total sum of cross-products. Also, a test statistic for white noise is proposed. It is

  16. Calculations on charge state and energy loss of argon ions in partially and fully ionized carbon plasmas.

    Science.gov (United States)

    Barriga-Carrasco, Manuel D; Casas, David; Morales, Roberto

    2016-03-01

    The energy loss of argon ions in a target depends on their velocity and charge density. At the energies studied in this work, it depends mostly on the free and bound electrons in the target. Here the random-phase approximation is used for analyzing free electrons at any degeneracy. For the plasma-bound electrons, an interpolation between approximations for low and high energies is applied. The Brandt-Kitagawa (BK) model is employed to depict the projectile charge space distribution, and the stripping criterion of Kreussler et al. is used to determine its equilibrium charge state Q(eq). This latter criterion implies that the equilibrium charge state depends slightly on the electron density and temperature of the plasma. On the other hand, the effective charge Q(eff) is obtained as the ratio between the energy loss of the argon ion and that of the proton for the same plasma conditions. This effective charge Q(eff) is larger than the equilibrium charge state Q(eq) due to the incorporation of the BK charge distribution. Though our charge-state estimations are not exactly the same as the experimental values, our energy loss agrees quite well with the experiments. It is noticed that the energy loss in plasmas is higher than that in the same cold target of about, ∼42-62.5% and increases with carbon plasma ionization. This confirms the well-known enhanced plasma stopping. It is also observed that only a small part of this energy loss enhancement is due to an increase of the argon charge state, namely only ∼2.2 and 5.1%, for the partially and the fully ionized plasma, respectively. The other contribution is connected with a better energy transfer to the free electrons at plasma state than to the bound electrons at solid state of about, ∼38.8-57.4%, where higher values correspond to a fully ionized carbon plasma.

  17. Cross sections for ionization of tetrahydrofuran by protons at energies between 300 and 3000 keV

    Science.gov (United States)

    Wang, Mingjie; Rudek, Benedikt; Bennett, Daniel; de Vera, Pablo; Bug, Marion; Buhr, Ticia; Baek, Woon Yong; Hilgers, Gerhard; Rabus, Hans

    2016-05-01

    Double-differential cross sections for ionization of tetrahydrofuran by protons with energies from 300 to 3000 keV were measured at the Physikalisch-Technische Bundesanstalt ion accelerator facility. The electrons emitted at angles between 15∘ and 150∘ relative to the ion-beam direction were detected with an electrostatic hemispherical electron spectrometer. Single-differential and total ionization cross sections have been derived by integration. The experimental results are compared to the semiempirical Hansen-Kocbach-Stolterfoht model as well as to the recently reported method based on the dielectric formalism. The comparison to the latter showed good agreement with experimental data in a broad range of emission angles and energies of secondary electrons. The scaling property of ionization cross sections for tetrahydrofuran was also investigated. Compared to molecules of different size, the ionization cross sections of tetrahydrofuran were found to scale with the number of valence electrons at large impact parameters.

  18. Biological Dosimetry Using Micronucleus Assay in Simulated Partial-Body Exposure to Ionizing Radiation

    Directory of Open Access Journals (Sweden)

    S. Purnami

    2017-08-01

    Full Text Available In radiation accidents, it is common that only several parts of the body are exposed to radiation. As a consequence there is a mixture of exposed and unexposed lymphocytes in peripheral blood cells of the samples. This phenomenon will cause the dose value estimated using the exposed lymphocytes to be lower than the actual dose. In this study, an assessment of partial body exposures using micronucleus assay by estimating the partial body dose and fraction of irradiated blood was conducted. An optimal D0 value also has been determined in this study to estimate the fraction of irradiated cells. Peripheral blood lymphocytes (PBLs from three healthy donors were irradiated in vitro with 2 Gy of X-rays. Partial radiation exposure was simulated by mixing the irradiated and non-irradiated blood in different proportions. The proportions of mixtures of blood samples irradiated in vitro were 5, 10, 15, 20, and 30 %. Blood samples were then cultured and harvested based on micronuclei assay protocol. At least 2000 binucleated cells with well-preserved cytoplasm were scored for the MN frequency. Dose Estimate 5.1 software was used to calculate the dispersion index (σ2/y and normalized unit of this index (U in each proportion of bloods. The fractions of irradiated cells were calculated with CABAS (Chromosomal Aberration Calculation Software for several different D0 values (2.7; 3.8; 5.4. The results showed that D0 value at 5.4 gave the closest results to the actual proportion of irradiated bloods, while for the dose estimation the estimated doses value from all proportions in all donors were higher than the actual dose. The factor that may cause this phenomenon was that the dose response calibration curve used to predict the radiation dose was not constructed in the laboratory used. Overall it can be concluded that a biodosimetry using MN assay can be used to estimate the radiation dose in partial body exposure. In order to establish a biodosimetry using MN

  19. Absolute cross sections for photoionization of Xeq+ ions (1 ⩽ q ⩽ 5) at the 3d ionization threshold

    International Nuclear Information System (INIS)

    Schippers, S; Ricz, S; Buhr, T; Borovik, A Jr; Hellhund, J; Holste, K; Huber, K; Schäfer, H-J; Schury, D; Klumpp, S; Mertens, K; Martins, M; Flesch, R; Ulrich, G; Rühl, E; Jahnke, T; Lower, J; Metz, D; Schmidt, L P H; Schöffler, M

    2014-01-01

    The photon-ion merged-beams technique has been employed at the new Photon-Ion spectrometer at PETRA III for measuring multiple photoionization of Xe q+ (q = 1–5) ions. Total ionization cross sections have been obtained on an absolute scale for the dominant ionization reactions of the type hν + Xe q+ → Xe r+ + (q − r)e − with product charge states q + 2 ⩽ r ⩽ q + 5. Prominent ionization features are observed in the photon-energy range 650–750 eV, which are associated with excitation or ionization of an inner-shell 3d electron. Single-configuration Dirac–Fock calculations agree quantitatively with the experimental cross sections for non-resonant photoabsorption, but fail to reproduce all details of the measured ionization resonance structures. (paper)

  20. K- and L-shell ionization cross sections for deuterons calculated in the ECPSSR theory

    International Nuclear Information System (INIS)

    Cohen, D.D.

    1989-01-01

    Ionization cross sections for K and L subshells are tabulated according to target atomic number and incident deuteron energy. Deuteron energies between 100 keV and 10 MeV and selected targets between C and Am for the K shell and between Ar and Am for the L subshells are used. The cross sections have been calculated in the plane-wave Born approximation (PWBA) with corrections for energy loss (E), Coulomb deflection (C), perturbed stationary states (PSS), and relativistic (R) effects (ECPSSR). Differences between the computational approach of Cohen and Harrigan and that of Brandt and Lapicki are delineated, and the ratios of the resulting cross sections are tabulated. Copyright 1989 Academic Press, Inc

  1. Power absorption of high-frequency electromagnetic waves in a partially ionized magnetized plasma

    International Nuclear Information System (INIS)

    Guo Bin; Wang Xiaogang

    2005-01-01

    Power absorption of high-frequency electromagnetic waves in a uniformly magnetized plasma layer covering a highly conducting surface is studied under atmosphere conditions. It is assumed that the system consists of not only electrons and positive ions but negative ions as well. By a general formula derived in our previous work [B. Guo and X. G. Wang, Plasma Sci. Tech. 7, 2645 (2005)], the total power absorption in the plasma layer with multiple reflections between an air-plasma interface and the conducting surface is computed. The results show that although the existence of negative ions greatly reduces the total power absorption, the magnetization of the plasma can, however, partially enhance it. Parameter dependence of the effects is calculated and discussed

  2. Absolute cross sections for the ionization-excitation of helium by electron impact

    Science.gov (United States)

    Bellm, S.; Lower, J.; Weigold, E.; Bray, I.; Fursa, D. V.; Bartschat, K.; Harris, A. L.; Madison, D. H.

    2008-09-01

    In a recent publication we presented detailed experimental and theoretical results for the electron-impact-induced ionization of ground-state helium atoms. The purpose of that work was to refine theoretical approaches and provide further insight into the Coulomb four-body problem. Cross section ratios were presented for transitions leading to excited states, relative to those leading to the ground state, of the helium ion. We now build on that study by presenting individual relative triple-differential ionization cross sections (TDCSs) for an additional body of experimental data measured at lower values of scattered-electron energies. This has been facilitated through the development of new electron-gun optics which enables us to accurately characterize the spectrometer transmission at low energies. The experimental results are compared to calculations resulting from a number of different approaches. For ionization leading to He+(1s2)1S , cross sections are calculated by the highly accurate convergent close-coupling (CCC) method. The CCC data are used to place the relative experimental data on to an absolute scale. TDCSs describing transitions to the excited states are calculated through three different approaches, namely, through a hybrid distorted- wave+R -matrix (close-coupling) model, through the recently developed four-body distorted-wave model, and by a first Born approximation calculation. Comparison of the first- and second-order theories with experiment allows for the accuracy of the different theoretical approaches to be assessed and gives insight into which physical aspects of the problem are most important to accurately model.

  3. Secondary-electron-production cross sections for electron-impact ionization of molecular nitrogen

    International Nuclear Information System (INIS)

    Goruganthu, R.R.; Wilson, W.G.; Bonham, R.A.

    1987-01-01

    Measurements of the double-differential cross section (DDCS), as a function of the ejected energy, angle, and primary energy for electron-impact ionization of molecular nitrogen are reported at incident energies of 200, 500, 1000, and 2000 eV. The ejection angle was varied from 30 0 to 150 0 in steps of 15 0 . The cross sections were obtained by use of a crossed-beam apparatus with an effusive gas source and a pulsed electron beam. Scattered and ejected electrons were energy analyzed by time-of-flight analysis from below 2 eV to the primary energy. The relative measurements were placed on an absolute scale by matching the experimental elastic differential cross sections to absolute measurements at each primary energy. Comparisons of the DDCS with previous reported values revealed significant differences. The DDCS were fitted to a Legendre polynomial expansion as a function of the ejection angle. Platzman plot analysis was carried out on the energy distributions determined from the fit coefficients. The total ionization cross sections at these primary energies were deduced from this plot. An autoionization feature at 2.3 eV was observed for the first time in measurements of this nature and has been assigned as due to a Rydberg state converging to the B 2 Σ/sub u/ + ionic state which decays to the X 2 Σ/sub g/ + ground state of N 2 + . An analysis of the autoionization lines observed in the present work in the range 0.4--2.5 eV is also presented

  4. Cross-Field Current Instabilities in Thin Ionization Layers and the Enhanced Aurora

    International Nuclear Information System (INIS)

    Johnson, Jay R.; Okuda, Hideo

    2008-01-01

    Nearly half of the time, auroral displays exhibit thin, bright layers known as 'enhanced aurora'. There is a substantial body of evidence that connects these displays with thin, dense, heavy ion layers in the E-region. Based on the spectral characteristics of the enhanced layers, it is believed that they result when wave-particle interaction heats ambient electrons to energies at or just above the 17 eV ionization energy of N2. While there are several possible instabilities that could produce suprathermal electrons in thin layers, there has been no clear theoretical investigation which examines in detail how wave instabilities in the thin ionization layers could develop and produce the suprathermal electrons. We examine instabilities which would occur in thin, dense, heavy ion layers using extensive analytical analysis combined with particle simulations. We analyze a cross field current instability that is found to be strongly unstable in the heavy ion layers. Electrostatic simulations show that substantial heating of the ambient electrons occurs with energization at or above the N2 ionization energy.

  5. Kinetic models of partially ionized complex plasmas in the low frequency regime

    International Nuclear Information System (INIS)

    Tolias, P.; Ratynskaia, S.; Angelis, U. de

    2011-01-01

    The results from three kinetic models of complex plasmas taking into account collisions with neutrals are compared in the low-frequency regime: The ''full'' model which considers the absorption of plasma fluxes on dust particles and dust charge fluctuations, the ''multi-component'' model where both these effects are neglected, and the ''standard'' model which takes into account the dust charge perturbations but not the absorption of fluxes. We derive and numerically evaluate expressions of the low frequency responses of these models, also taking into account the modification of the capture cross-sections due to the effect of neutrals. The role of plasma sources and collisions with neutrals is assessed by computing the plasma permittivities and static permittivities for all the three models.

  6. Kinetic theory of cross-modulation in a weakly ionized plasma

    International Nuclear Information System (INIS)

    Garrett, A.J.M.

    1991-01-01

    Cross-modulation in plasma is an electromagnetic wave interaction in which the modulation of one 'disturbing' wave is imposed nonlinearly on the transport properties of the medium, and thence onto a second, 'wanted' wave propagating linearly through it. This analysis is restricted to weakly ionized plasma with allowance for ambient magnetic field, as in the lower ionosphere. A kinetic description is used, based on the Boltzmann equation for the electrons, with electron-molecule collisions described by Boltzmann's collision integral. Because of the small mass ratio this simplifies to a differential form. There is no cross-modulation if the collision frequency is independent of collision speed, when contributions from all parts of velocity space cancel. (author)

  7. Computation of electron-impact K-shell ionization cross sections of atoms

    International Nuclear Information System (INIS)

    Uddin, M.A.; Haque, A.K.F.; Billah, M. Masum; Basak, A.K.; Karim, K.R.; Saha, B.C.

    2005-01-01

    The total cross sections of electron impact single K-shell ionization of atomic targets, with a wide range of atomic numbers from Z=6-50, are evaluated in the energy range up to about 10 MeV employing the recently proposed modified version of the improved binary-encounter dipole (RQIBED) model [Uddin et al., Phys. Rev. A 70, 032706 (2004)], which incorporates the ionic and relativistic effects. The experimental cross sections for all targets are reproduced satisfactorily even in the relativistic energies using fixed generic values of the two parameters in the RQIBED model. The relativistic effect is found to be significant in all targets except for C, being profound in Ag and Sn

  8. Differential and total cross sections for the ionization of water molecule by electron impact

    International Nuclear Information System (INIS)

    Houamer, S.; Dal Cappello, C.; Mansouri, A.

    2007-01-01

    A theoretical approach is presented to calculate multiply differential and total cross sections of the ionization of H 2 O molecule in the vapour phase. The wave function of the target is described by molecular orbitals consisting of a linear combination of slater type atomic orbitals centered on the heaviest atom which is the oxygen atom in this case. The calculations are carried out in the first Born approximation where the projectile is described by a plane wave while the ejected electron is described by a coulomb wave taking into account its interaction with the residual ion. The spherical average over the Euler solid angle due to the randomly oriented gaseous target molecule is carried out analytically using the rotation matrix properties. The differential and total cross sections are thus evaluated without any special difficulty and compared with experiments and distorted wave calculations. Fair agreements are observed

  9. Differential cross sections for single ionization of H2 by 75-keV proton impact

    International Nuclear Information System (INIS)

    Chowdhury, U.; Schulz, M.; Madison, D. H.

    2011-01-01

    We have calculated triply differential cross sections (TDCS) and doubly differential cross sections (DDCS) for single ionization of H 2 by 75-keV proton impact using the molecular three-body distorted-wave-eikonal initial-state (M3DW-EIS) approach. Previously published measured DDCS (differential in the projectile scattering angle and integrated over the ejected electron angles) found pronounced structures at relatively large angles that were interpreted as an interference resulting from the two-centered potential of the molecule. Theory treating H 2 as atomic H multiplied by a molecular interference factor only predicts the observed structure when assumptions are made about the molecular orientation. Here we apply the M3DW-EIS method, which does not rely on such an ad hoc approach, but rather treats the interference from first principles.

  10. Integral elastic, electronic-state, ionization, and total cross sections for electron scattering with furfural

    Science.gov (United States)

    Jones, D. B.; da Costa, R. F.; Varella, M. T. do N.; Bettega, M. H. F.; Lima, M. A. P.; Blanco, F.; García, G.; Brunger, M. J.

    2016-04-01

    We report absolute experimental integral cross sections (ICSs) for electron impact excitation of bands of electronic-states in furfural, for incident electron energies in the range 20-250 eV. Wherever possible, those results are compared to corresponding excitation cross sections in the structurally similar species furan, as previously reported by da Costa et al. [Phys. Rev. A 85, 062706 (2012)] and Regeta and Allan [Phys. Rev. A 91, 012707 (2015)]. Generally, very good agreement is found. In addition, ICSs calculated with our independent atom model (IAM) with screening corrected additivity rule (SCAR) formalism, extended to account for interference (I) terms that arise due to the multi-centre nature of the scattering problem, are also reported. The sum of those ICSs gives the IAM-SCAR+I total cross section for electron-furfural scattering. Where possible, those calculated IAM-SCAR+I ICS results are compared against corresponding results from the present measurements with an acceptable level of accord being obtained. Similarly, but only for the band I and band II excited electronic states, we also present results from our Schwinger multichannel method with pseudopotentials calculations. Those results are found to be in good qualitative accord with the present experimental ICSs. Finally, with a view to assembling a complete cross section data base for furfural, some binary-encounter-Bethe-level total ionization cross sections for this collision system are presented.

  11. Integral elastic, electronic-state, ionization, and total cross sections for electron scattering with furfural

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Costa, R. F. da [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo (Brazil); Departamento de Física, Universidade Federal do Espírito Santo, 29075-910, Vitória, Espírito Santo (Brazil); Varella, M. T. do N. [Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo (Brazil); Bettega, M. H. F. [Departamento de Física, Universidade Federal do Paraná, CP 19044, 81531-990 Curitiba, Paraná (Brazil); Lima, M. A. P. [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo (Brazil); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid E-28040 (Spain); García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2016-04-14

    We report absolute experimental integral cross sections (ICSs) for electron impact excitation of bands of electronic-states in furfural, for incident electron energies in the range 20–250 eV. Wherever possible, those results are compared to corresponding excitation cross sections in the structurally similar species furan, as previously reported by da Costa et al. [Phys. Rev. A 85, 062706 (2012)] and Regeta and Allan [Phys. Rev. A 91, 012707 (2015)]. Generally, very good agreement is found. In addition, ICSs calculated with our independent atom model (IAM) with screening corrected additivity rule (SCAR) formalism, extended to account for interference (I) terms that arise due to the multi-centre nature of the scattering problem, are also reported. The sum of those ICSs gives the IAM-SCAR+I total cross section for electron–furfural scattering. Where possible, those calculated IAM-SCAR+I ICS results are compared against corresponding results from the present measurements with an acceptable level of accord being obtained. Similarly, but only for the band I and band II excited electronic states, we also present results from our Schwinger multichannel method with pseudopotentials calculations. Those results are found to be in good qualitative accord with the present experimental ICSs. Finally, with a view to assembling a complete cross section data base for furfural, some binary-encounter-Bethe-level total ionization cross sections for this collision system are presented.

  12. Integral elastic, electronic-state, ionization, and total cross sections for electron scattering with furfural

    International Nuclear Information System (INIS)

    Jones, D. B.; Costa, R. F. da; Varella, M. T. do N.; Bettega, M. H. F.; Lima, M. A. P.; Blanco, F.; García, G.; Brunger, M. J.

    2016-01-01

    We report absolute experimental integral cross sections (ICSs) for electron impact excitation of bands of electronic-states in furfural, for incident electron energies in the range 20–250 eV. Wherever possible, those results are compared to corresponding excitation cross sections in the structurally similar species furan, as previously reported by da Costa et al. [Phys. Rev. A 85, 062706 (2012)] and Regeta and Allan [Phys. Rev. A 91, 012707 (2015)]. Generally, very good agreement is found. In addition, ICSs calculated with our independent atom model (IAM) with screening corrected additivity rule (SCAR) formalism, extended to account for interference (I) terms that arise due to the multi-centre nature of the scattering problem, are also reported. The sum of those ICSs gives the IAM-SCAR+I total cross section for electron–furfural scattering. Where possible, those calculated IAM-SCAR+I ICS results are compared against corresponding results from the present measurements with an acceptable level of accord being obtained. Similarly, but only for the band I and band II excited electronic states, we also present results from our Schwinger multichannel method with pseudopotentials calculations. Those results are found to be in good qualitative accord with the present experimental ICSs. Finally, with a view to assembling a complete cross section data base for furfural, some binary-encounter-Bethe-level total ionization cross sections for this collision system are presented.

  13. Surface oxidation on thin films affects ionization cross section induced by proton beam

    International Nuclear Information System (INIS)

    Bertol, Ana Paula Lamberti; Vasconcellos, M.A.Z.; Hinrichs, Ruth; Limandri, Silvina; Trincavelli, Jorge

    2012-01-01

    Full text: In microanalysis techniques such as Particle Induced X-ray Emission (PIXE), the transformation from intensity to concentration is made by standard less software that needs exact values of fundamental parameters such as the ionization cross section, transition probabilities of the different electronic levels, and fluorescent yield. The three parameters together measure the photon generating probability of an electronic transition and can be determined experimentally under the name of production cross section. These measurements are performed on thin films, with thickness around 10 nm, but most studies do not take into account any spontaneous surface oxidation. In this work, in the attempt to obtain cross section values of Al, Si and Ti, in metallic and oxide films, the influence of surface oxidation on the metallic films was established. Simulations considering the oxidation with the software SIMNRA on the Rutherford backscattering (RBS) spectra obtained from the films provided mass thickness values used to calculate the cross section data that were compared with theoretical values (PWBA and ECPSSR), and with experimental values and empirical adjustments from other studies. The inclusion of the natural oxidation affects the values of cross section, and may be one of the causes of discrepancies between the experimental values published in literature. (author)

  14. Electron ejection cross sections in electron and ion impact ionization: Ab initio and semiempirical calculations

    International Nuclear Information System (INIS)

    Manson, S.T.; Miller, J.H.; Pacific Northwest Lab., Richland, WA)

    1983-01-01

    Ionization cross sections for heavy ions and electrons incident on various atoms and molecules are required in the modeling of the interaction of radiation with matter. For each case, the energy distribution of secondary electrons (the single differential cross section, SDCS) is needed over a broad range of projectile and secondary electron (delta-ray) energies. In many cases the energy and angular distribution of secondary electrons (the double differential cross section, DDCS) is also necessary. Clearly, it would be desirable to have laboratory SDCS and DDCS measurements for all of the cases required. For a variety of reasons, this is not yet possible. Thus, one must turn elsewhere to obtain the needed cross sections. In this paper, we discuss cross sections obtained in two different ways; ab initio theory based on the first Born approximation, and a semi-empirical method based on the Bethe-Born Approximation. In both cases, results on helium will be presented since the largest amount of data is available in this case. Applications of both methods to other target species are given in the references. The accuracy of the methods and plans for the near future are also discussed. 23 references, 6 figures

  15. Detrended partial cross-correlation analysis of two nonstationary time series influenced by common external forces

    Science.gov (United States)

    Qian, Xi-Yuan; Liu, Ya-Min; Jiang, Zhi-Qiang; Podobnik, Boris; Zhou, Wei-Xing; Stanley, H. Eugene

    2015-06-01

    When common factors strongly influence two power-law cross-correlated time series recorded in complex natural or social systems, using detrended cross-correlation analysis (DCCA) without considering these common factors will bias the results. We use detrended partial cross-correlation analysis (DPXA) to uncover the intrinsic power-law cross correlations between two simultaneously recorded time series in the presence of nonstationarity after removing the effects of other time series acting as common forces. The DPXA method is a generalization of the detrended cross-correlation analysis that takes into account partial correlation analysis. We demonstrate the method by using bivariate fractional Brownian motions contaminated with a fractional Brownian motion. We find that the DPXA is able to recover the analytical cross Hurst indices, and thus the multiscale DPXA coefficients are a viable alternative to the conventional cross-correlation coefficient. We demonstrate the advantage of the DPXA coefficients over the DCCA coefficients by analyzing contaminated bivariate fractional Brownian motions. We calculate the DPXA coefficients and use them to extract the intrinsic cross correlation between crude oil and gold futures by taking into consideration the impact of the U.S. dollar index. We develop the multifractal DPXA (MF-DPXA) method in order to generalize the DPXA method and investigate multifractal time series. We analyze multifractal binomial measures masked with strong white noises and find that the MF-DPXA method quantifies the hidden multifractal nature while the multifractal DCCA method fails.

  16. Measurement of differential (n,x{alpha}) cross section using 4{pi} gridded ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Sanami, Toshiya; Baba, Mamoru; Matsuyama, Shigeo; Kiyosumi, Takehide; Nauchi, Yasushi; Saito, Keiichiro; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering; Kawano, Toshihiko

    1997-03-01

    We carried out the measurements of high resolution {alpha} emission spectra of {sup 58}Ni and {sup nat}Ni between 4.5 and 6.5 MeV, and {sup 12}C(n,x{alpha}) cross section using a 4{pi} gridded ionization chamber. In Ni measurement, overall energy resolution was improved to around 200 keV by optimizing a sample thickness and a neutron source width. Measured alpha spectra showed separate peaks corresponding to the ground and low-lying excited states of the residual nucleus ({sup 55}Fe). These results were compared with another direct measurement and statistical model calculations. In {sup 12}C measurement, GIC was applied for (n,x{alpha}) reactions of light nuclei. This application is difficult to (n,x{alpha}) cross sections of light nuclei, because of the influences of large recoil energy and multi-body break-up. We developed new methods which eliminate the effects of recoil nuclei and multi-body break-up and applied them to {sup 12}C(n,x{alpha}) reaction at En=14.1 MeV. In our experiment, the {sup 12}C(n,{alpha}{sub 0}){sup 9}Be angular differential cross section and {sup 12}C(n,n`3{alpha}) cross section were obtained. (author)

  17. Absolute experimental cross sections for the electron impact ionization of rubidium. Technical summary report

    International Nuclear Information System (INIS)

    Hughes, D.W.; Feeney, R.K.

    1980-01-01

    The absolute cross sections for the double, triple, and quadruple ionization of Rb + ions by electron impact have been measured from below their respective thresholds to approximately 3000 eV. This determination has been accomplished using a crossed beam facility in which monoenergetic beams of ions and electrons are caused to intersect at right angles in a well-defined collision volume. Multiply charged, product ions born as a result of the electron impact are deflected into their respective detectors by cascaded electrostatic analyzers. The multiply charged beam current component is measured by means of a vibrating reed electrometer operating in the rate-of-charge mode. The required singly charged rubidium ions are produced in a thermionic ion source and pass through a series of focusing, collimating and deflecting structures before entering the interaction region. A thermionically generated, rectangular electron beam intercepts the target ions in a spatially designated collision volume. Just prior to entering this interaction region the two beams can be made to pass through a movable slit scanner which determines their spatial profiles. The various charged particle currents, energies and beam current density distributions represent the experimental data from which the desired absolute cross sections have been determined. The results obtained with this technique are compared with available theoretical predictions of the appropriate cross sections

  18. Communication: Electron ionization of DNA bases

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, M. A.; Krishnakumar, E., E-mail: ekkumar@tifr.res.in

    2016-04-28

    No reliable experimental data exist for the partial and total electron ionization cross sections for DNA bases, which are very crucial for modeling radiation damage in genetic material of living cell. We have measured a complete set of absolute partial electron ionization cross sections up to 500 eV for DNA bases for the first time by using the relative flow technique. These partial cross sections are summed to obtain total ion cross sections for all the four bases and are compared with the existing theoretical calculations and the only set of measured absolute cross sections. Our measurements clearly resolve the existing discrepancy between the theoretical and experimental results, thereby providing for the first time reliable numbers for partial and total ion cross sections for these molecules. The results on fragmentation analysis of adenine supports the theory of its formation in space.

  19. Level-resolved distorted-wave cross-sections of electron impact ionization of Ar{sup 5+}

    Energy Technology Data Exchange (ETDEWEB)

    Yumak, A; Yavuz, I; Altun, Z, E-mail: zikalt@superonline.co [Department of Physics, Marmara University, Istanbul, 34722 (Turkey)

    2009-11-01

    Electron impact ionization cross sections of Ar{sup 5+} were calculated using configuration-average (CADW) and level-resolved (LRDW) distorted-wave methods. Direct ionization cross-sections of 2s, 2p, 3s and 3p subshells were calculated within a CADW approximation. The contributions from the excitation autoionization channels were evaluated assuming single excitations from the 2s, 2p, and 3s subshells and in both CADW and LRDW methods. The radiative stabilization of the excitation autoionization channels were found to reduce the excitation autoionization by a small amount.

  20. The role of projectile interactions in triply differential cross sections for excitation-ionization of helium

    Energy Technology Data Exchange (ETDEWEB)

    Dey, R., E-mail: ritud@ipp.mpg.d [Max-Planck Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany); Roy, A.C. [School of Mathematical Sciences, Ramakrishna Mission Vivekananda University, Belur Math 711 202, West Bengal (India)

    2011-02-01

    We report triply differential cross section (TDCS) for the simultaneous excitation-ionization of helium by electron impact for both coplanar and non-coplanar geometry. In the coplanar case, calculations have been performed for an incident energy of 500 eV and low ejection energies (3 and 10 eV), whereas in the noncoplanar case we have considered impact energies in the range 1240-4260 eV for a symmetric geometry. The present calculation is based on the eikonal approximation due to Glauber. We have incorporated the effect of post-collision interaction in the Glauber approximation. A comparison is made of the present calculations with the results of other theoretical methods and recent experiments. The Glauber results are in reasonably good agreement with the experiment for small scattering angles.

  1. Electron capture to the continuum manifestation in fully differential cross sections for ion impact single ionization

    Science.gov (United States)

    Ciappina, M. F.; Fojón, O. A.; Rivarola, R. D.

    2018-04-01

    We present theoretical calculations of single ionization of He atoms by protons and multiply charged ions. The kinematical conditions are deliberately chosen in such a way that the ejected electron velocity matches the projectile impact velocity. The computed fully differential cross sections (FDCS) in the scattering plane using the continuum-distorted wave-eikonal initial state show a distinct peaked structure for a polar electron emission angle θ k = 0°. This element is absent when a first order theory is employed. Consequently, we can argue that this peak is a clear manifestation of a three-body effect, not observed before in FDCS. We discuss a possible interpretation of this new feature.

  2. Experimental and theoretical double differential cross sections for electron impact ionization of methane

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, Murat; Ozer, Zehra Nur, E-mail: zehraerengil@aku.edu.tr; Ulu, Melike; Dogan, Mevlut [e-COL Laboratory, Department of Physics, Afyon Kocatepe University, Afyonkarahisar 03200 (Turkey); Champion, Christophe [Centre d’Etudes Nucléaires de Bordeaux Gradignan, CNRS/IN2P3, Université de Bordeaux, Gradignan 33170 (France)

    2016-04-28

    Experimental and theoretical double differential cross sections (DDCSs) for electron-induced ionization of methane (CH{sub 4}) are here reported for primary energies ranging from 50 eV to 350 eV and ejection angles between 25° and 130°. Experimental DDCSs are compared with theoretical predictions performed within the first Born approximation Coulomb wave. In this model, the initial molecular state is described by using single center wave functions, the incident (scattered) electron being described by a plane wave, while a Coulomb wave function is used for modeling the secondary ejected electron. A fairly good agreement may be observed between theory and experiment with nevertheless an expected systematic overestimation of the theory at low-ejection energies (<50 eV).

  3. Cross sections and coherence terms for associative ionization of two differently excited Na(3p) atoms

    International Nuclear Information System (INIS)

    Meijer, H.A.J.; Pelgrim, T.J.C.; Heideman, H.G.M.; Morgenstern, R.; Andersen, N.

    1988-01-01

    The associative ionization process in thermal Na(3p)-Na(3p) encounters has been studied in a series of crossed-beam experiments where the light polarization of the two laser beams preparing the excited atoms before collision was varied independently. It is shown how in this way maximum possible information for our geometry is extracted about the dependence of the ion formation process on the shape and spatial orientation of the electron clouds of the two approaching atoms, including all coherence terms. The experimental findings are discussed in the light of recent theoretical results for the states of the Na 2 molecule. It is concluded that just a few of the possible geometrical approaches are favourable for molecular-ion formation. (orig.)

  4. Double ionization of the hydrogen sulfide molecule by electron impact: Influence of the target orientation on multiple differential cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Imadouchene, N. [Laboratoire de Mécanique, Structures et Energétique Université Mouloud Mammeri de Tizi-Ouzou, B.P. 17, Tizi-Ouzou 15000 (Algeria); Aouchiche, H., E-mail: h_aouchiche@yahoo.fr [Laboratoire de Mécanique, Structures et Energétique Université Mouloud Mammeri de Tizi-Ouzou, B.P. 17, Tizi-Ouzou 15000 (Algeria); Champion, C. [Centre d’Etudes Nucléaires de Bordeaux Gradignan, Université Bordeaux, CNRS/IN2P3, Boîte Postale 120, Gradignan 33175 (France)

    2016-07-15

    Highlights: • The double ionization of the H{sub 2}S molecule is here theoretically studied. • The orientation dependence of the differential cross sections is scrutinized. • The specific double ionizing mechanisms are clearly identified. - Abstract: Multiple differential cross sections of double ionization of hydrogen sulfide molecule impacted by electrons are here investigated within the first Born approximation. In the initial state, the incident electron is represented by a plane wave function whereas the target is described by means of a single-center molecular wave function. In the final state, the two ejected electrons are described by Coulomb wave functions coupled by the Gamow factor, whereas the scattered electron is described by a plane wave. In this work, we analyze the role played by the molecular target orientation in the double ionization of the four outermost orbitals, namely 2b{sub 1}, 5a{sub 1}, 2b{sub 2} and 4a{sub 1} in considering the particular case of two electrons ejected from the same orbital. The contribution of each final state to the double ionization process is studied in terms of shape and magnitude for specific molecular orientations and for each molecular orbital we identified the mechanisms involved in the double ionization process, namely, the Shake-Off and the Two-Step 1.

  5. Electrospray ionization mass spectrometry and partial least squares discriminant analysis applied to the quality control of olive oil.

    Science.gov (United States)

    Alves, Junia O; Botelho, Bruno G; Sena, Marcelo M; Augusti, Rodinei

    2013-10-01

    Direct infusion electrospray ionization mass spectrometry in the positive ion mode [ESI(+)-MS] is used to obtain fingerprints of aqueous-methanolic extracts of two types of olive oils, extra virgin (EV) and ordinary (OR), as well as of samples of EV olive oil adulterated by the addition of OR olive oil and other edible oils: corn (CO), sunflower (SF), soybean (SO) and canola (CA). The MS data is treated by the partial least squares discriminant analysis (PLS-DA) protocol aiming at discriminating the above-mentioned classes formed by the genuine olive oils, EV (1) and OR (2), as well as the EV adulterated samples, i.e. EV/SO (3), EV/CO (4), EV/SF (5), EV/CA (6) and EV/OR (7). The PLS-DA model employed is built with 190 and 70 samples for the training and test sets, respectively. For all classes (1-7), EV and OR olive oils as well as the adulterated samples (in a proportion varying from 0.5 to 20.0% w/w) are properly classified. The developed methodology required no ions identification and demonstrated to be fast, as each measurement lasted about 3 min including the extraction step and MS analysis, and reliable, because high sensitivities (rate of true positives) and specificities (rate of true negatives) were achieved. Finally, it can be envisaged that this approach has potential to be applied in quality control of EV olive oils. Copyright © 2013 John Wiley & Sons, Ltd.

  6. Collaborative Research: A Model of Partially Ionized Plasma Flows with Kinetic Treatment of Neutral Atoms and Nonthermal Ions

    International Nuclear Information System (INIS)

    Pogorelov, Nikolai; Zhang, Ming

    2016-01-01

    Interactions of flows of partially ionized, magnetized plasma are frequently accompanied by the presence of both thermal and non-thermal (pickup) ion components. Such interactions cannot be modeled using traditional MHD equations and require more advanced approaches to treat them. If a nonthermal component of ions is formed due to charge exchange and collisions between the thermal (core) ions and neutrals, it experiences the action of magnetic field, its distribution function is isotropized, and it soon acquires the velocity of the ambient plasma without being thermodynamically equilibrated. This situation, e. g., takes place in the outer heliosphere -- the part of interstellar space beyond the solar system whose properties are determined by the solar wind interaction with the local interstellar medium. This is also possible in laboratory, at million degrees and above, when plasma is conducting electricity far too well, which makes Ohmic heating ineffective. To attain the target temperatures one needs additional heating eventually playing a dominant role. Among such sources is a so-called neutral particle beam heating. This is a wide-spread technique (Joint European Torus and International Thermonuclear Experimental Reactor experiments) based on the injection of powerful beams of neutral atoms into ohmically preheated plasma. In this project we have investigated the energy and density separation between the thermal and nonthermal components in the solar wind and interstellar plasmas. A new model has been developed in which we solve the ideal MHD equations for mixture of all ions and the kinetic Boltzmann equation to describe the transport of neutral atoms. As a separate capability, we can treat the flow of neutral atoms in a multi-component fashion, where neutral atoms born in each thermodynamically distinct region are governed by the Euler gas dynamic equations. We also describe the behavior of pickup ions either kinetically, using the Fokker--Planck equation, or

  7. Collaborative Research: A Model of Partially Ionized Plasma Flows with Kinetic Treatment of Neutral Atoms and Nonthermal Ions

    Energy Technology Data Exchange (ETDEWEB)

    Pogorelov, Nikolai [Univ. of Alabama, Huntsville, AL (United States); Zhang, Ming [Florida Inst. of Technology, Melbourne, FL (United States)

    2016-07-31

    Interactions of flows of partially ionized, magnetized plasma are frequently accompanied by the presence of both thermal and non-thermal (pickup) ion components. Such interactions cannot be modeled using traditional MHD equations and require more advanced approaches to treat them. If a nonthermal component of ions is formed due to charge exchange and collisions between the thermal (core) ions and neutrals, it experiences the action of magnetic field, its distribution function is isotropized, and it soon acquires the velocity of the ambient plasma without being thermodynamically equilibrated. This situation, e. g., takes place in the outer heliosphere –- the part of interstellar space beyond the solar system whose properties are determined by the solar wind interaction with the local interstellar medium. This is also possible in laboratory, at million degrees and above, when plasma is conducting electricity far too well, which makes Ohmic heating ineffective. To attain the target temperatures one needs additional heating eventually playing a dominant role. Among such sources is a so-called neutral particle beam heating. This is a wide-spread technique (Joint European Torus and International Thermonuclear Experimental Reactor experiments) based on the injection of powerful beams of neutral atoms into ohmically preheated plasma. In this project we have investigated the energy and density separation between the thermal and nonthermal components in the solar wind and interstellar plasmas. A new model has been developed in which we solve the ideal MHD equations for mixture of all ions and the kinetic Boltzmann equation to describe the transport of neutral atoms. As a separate capability, we can treat the flow of neutral atoms in a multi-component fashion, where neutral atoms born in each thermodynamically distinct region are governed by the Euler gas dynamic equations. We also describe the behavior of pickup ions either kinetically, using the Fokker--Planck equation

  8. Collaborative Research: A Model of Partially Ionized Plasma Flows with Kinetic Treatment of Neutral Atoms and Nonthermal Ions

    Energy Technology Data Exchange (ETDEWEB)

    Pogorelov, Nikolai [Univ. of Alabama, Huntsville, AL (United States). Dept. of Space Science. Center for Space Plasma and; Zhang, Ming [Florida Inst. of Technology, Melbourne, FL (United States). Physics and Space Sciences Dept.; Borovikov, Sergey [Univ. of Alabama, Huntsville, AL (United States). Dept. of Space Science. Center for Space Plasma and Aeronomic Research; Heerikhuisen, Jacob [Univ. of Alabama, Huntsville, AL (United States). Dept. of Space Science. Center for Space Plasma and Aeronomic Research; Zank, Gary [Univ. of Alabama, Huntsville, AL (United States). Dept. of Space Science. Center for Space Plasma and Aeronomic Research; Gamayunov, Konstantin [Florida Inst. of Technology, Melbourne, FL (United States). Physics and Space Sciences Dept.; Colella, Phillip [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-07-31

    Interactions of flows of partially ionized, magnetized plasma are frequently accompanied by the presence of both thermal and non-thermal (pickup) ion components. Such interactions cannot be modeled using traditional MHD equations and require more advanced approaches to treat them. If a nonthermal component of ions is formed due to charge exchange and collisions between the thermal (core) ions and neutrals, it experiences the action of magnetic field, its distribution function is isotropized, and it soon acquires the velocity of the ambient plasma without being thermodynamically equilibrated. This situation, e. g., takes place in the outer heliosphere - the part of interstellar space beyond the solar system whose properties are determined by the solar wind interaction with the local interstellar medium. This is also possible in laboratory, at million degrees and above, when plasma is conducting electricity far too well, which makes Ohmic heating ineffective. To attain the target temperatures one needs additional heating eventually playing a dominant role. Among such sources is a so-called neutral particle beam heating. This is a wide-spread technique (Joint European Torus and International Thermonuclear Experimental Reactor experiments) based on the injection of powerful beams of neutral atoms into ohmically preheated plasma. In this project we have investigated the energy and density separation between the thermal and nonthermal components in the solar wind and interstellar plasmas. A new model has been developed in which we solve the ideal MHD equations for mixture of all ions and the kinetic Boltzmann equation to describe the transport of neutral atoms. As a separate capability, we can treat the flow of neutral atoms in a multi-component fashion, where neutral atoms born in each thermodynamically distinct regions are governed by the Euler gas dynamic equations. We also describe the behavior of pickup ions either kinetically, using the Fokker–Planck equation, or

  9. Effect of surface potential and intrinsic magnetic field on resistance of a body in a supersonic flow of rarefied partially ionized gas

    International Nuclear Information System (INIS)

    Shuvalov, V.A.

    1986-01-01

    The character of flow over a body, structure of the perturbed zone, and flow resistance in a supersonic flow of rarefied partially ionized gas are determined by the intrinsic magnetic field and surface potential of the body. There have been practically no experimental studies of the effect of intrinsic magnetic field on flow of a rarefied plasma. Studies of the effect of surface potential have been limited to the case R/λd 10 2 (where R is the characteristic dimension of the body and λd is the Debye radius). At the same time R/λd > 10 2 , the regime of flow over a large body, is of the greatest practical interest. The present study will consider the effect of potential and intrinsic magnetic field on resistance of a large (R/λd > 10 2 ) axisymmetric body (disk, sphere) in a supersonic flow of rarefield partially ionized gas

  10. Code implementation of partial-range angular scattering cross sections: GAMMER and MORSE

    International Nuclear Information System (INIS)

    Ward, J.T. Jr.

    1978-01-01

    A partial-range (finite-element) method has been previously developed for representing multigroup angular scattering in Monte Carlo photon transport. Computer application of the method, with preliminary quantitative results is discussed here. A multigroup photon cross section processing code, GAMMER, was written which utilized ENDF File 23 point data and the Klein--Nishina formula for Compton scattering. The cross section module of MORSE, along with several execution routines, were rewritten to permit use of the method with photon transport. Both conventional and partial-range techniques were applied for comparison to calculating angular and spectral penetration of 6-MeV photons through a six-inch iron slab. GAMMER was found to run 90% faster than SMUG, with further improvement evident for multiple-media situations; MORSE cross section storage was reduced by one-third; cross section processing, greatly simplified; and execution time, reduced by 15%. Particle penetration was clearly more forward peaked, as moment accuracy is retained to extremly high order. This method of cross section treatment offers potential savings in both storage and handling, as well as improved accuracy and running time in the actual execution phase. 3 figures, 4 tables

  11. Partial and total electronic stopping cross sections of atoms and solids for protons

    International Nuclear Information System (INIS)

    Kaneko, Toshiaki.

    1990-12-01

    Based on a wave packet theory (Phys. Rev. A40, 2188(1989); Phys. Stat. Sol. (B)156,49(1989)), partial and total electronic cross sections of target elements in atomic and solid phases with atomic number Z ranging from 2 (He) to 92 (U) are tabulated shell by shell for protons with velocity v from 0.2V 0 to 2OV 0 (V 0 =2.18 x 10 8 cm/s). (author)

  12. Triple differential cross section for the ionization of helium by electronic impact

    Energy Technology Data Exchange (ETDEWEB)

    Diallo, Saidou, E-mail: saidou40@yahoo.fr [Laboratoire de Physique des Plasmas et de Recherches Interdisciplinaires, Universite Cheikh Anta Diop, Faculte des Sciences et Techniques, Departement de Physique, BP: 5005 Dakar-Fann (Senegal); Faye, I.G.; Diedhiou, I.A.; Tall, M.S.; Gomis, L.; Diatta, C.S. [Laboratoire de Physique des Plasmas et de Recherches Interdisciplinaires, Universite Cheikh Anta Diop, Faculte des Sciences et Techniques, Departement de Physique, BP: 5005 Dakar-Fann (Senegal)

    2011-12-01

    We report results of analytical triple differential cross sections (TDCS) for the single ionization of the helium iso-electronic ions by the electron impact. A two variational parameters wave function is used to evaluate the TDCS. This study shows the accuracy of the TDCS for helium atom and helium like ions in the first Born approximation (FBA) at high incident energy domain. The theory is quite acceptable as a fast calculation of the triple differential cross section, particularly at high energies where other theories and methods are cumbersome. A comparison is made of our calculations with previous results of the other theoretical methods and experiment. The FBA results obtained here with the two variational parameters wave function are in good agreement with the experiment data at high incident energy. The results show that the electron correlation effects are important around the maxima and influence only the extrema magnitude but not their positions. The calculations presented here are extanded to the cases where the energies of the outgoing electrons are more equal.

  13. Total and single differential cross sections for the electron impact ionization of the ground state of helium

    International Nuclear Information System (INIS)

    Singh, T.S.C.; Choudhury, K.B.; Singh, M.B.; Deb, N.C.; Mukherjee, S.C.; Mazumdar, P.S.

    1997-01-01

    Total cross sections (TCS) and single differential cross sections (SDCS) have been computed for the single ionization of the ground state of helium by electron impact in a distorted wave formalism which takes into account the effects of the initial and final channel distortions. The present TCS and SDCS results are in fair agreement with the measured values and other theoretical predictions for the incident electron energy E i > 150 eV. (orig.)

  14. Collision energy-resolved study of the emission cross-section and the Penning ionization cross-section in the reaction of BrCN with He*(2 3S)

    Science.gov (United States)

    Kanda, Kazuhiro; Yamakita, Yoshihiro; Ohno, Koichi

    2001-12-01

    The dissociative excitation of BrCN producing CN(B 2Σ +) fragment by the collision of He *(2 3S) was investigated by the collision energy-resolved electron and emission spectroscopy using time-of-flight method with a high-intensity He * beam. The Penning electrons ejected from BrCN and the subsequent CN ( B2Σ +- X2Σ +) emission were measured as a function of collision energy in the range of 90-180 meV. The formation of CN ( B2Σ +) is concluded to proceed dominantly via the promotion of an electron from Π-character orbital, by comparison between the collision energy dependence of the partial Penning ionization cross-sections and the CN ( B2Σ +- X2Σ +) emission cross-section.

  15. Fully differential cross sections for the single ionization of helium by fast ions: Classical model calculations

    Science.gov (United States)

    Sarkadi, L.

    2018-04-01

    Fully differential cross sections (FDCSs) have been calculated for the single ionization of helium by 1- and 3-MeV proton and 100-MeV/u C6 + ion impact using the classical trajectory Monte Carlo (CTMC) method in the nonrelativistic, three-body approximation. The calculations were made employing a Wigner-type model in which the quantum-mechanical position distribution of the electron is approximated by a weighted integral of the microcanonical distribution over a range of the binding energy of the electron. In the scattering plane, the model satisfactorily reproduces the observed shape of the binary peak. In the region of the peak the calculated FDCSs agree well with the results of continuum-distorted-wave calculations for all the investigated collisions. For 1-MeV proton impact the experimentally observed shift of the binary peak with respect to the first Born approximation is compared with the shifts obtained by different higher-order quantum-mechanical theories and the present CTMC method. The best result was achieved by CTMC, but still a large part of the shift remained unexplained. Furthermore, it was found that the classical theory failed to reproduce the shape of the recoil peak observed in the experiments, it predicts a much narrower peak. This indicates that the formation of the recoil peak is dominated by quantum-mechanical effects. For 100-MeV/u C6 + ion impact the present CTMC calculations confirmed the existence of the "double-peak" structure of the angular distribution of the electron in the plane perpendicular to the momentum transfer, in accordance with the observation, the prediction of an incoherent semiclassical model, and previous CTMC results. This finding together with wave-packet calculations suggests that the "C6 + puzzle" may be solved by considering the loss of the projectile coherence. Experiments to be conducted using ion beams of anisotropic coherence are proposed for a more differential investigation of the ionization dynamics.

  16. (e, 2e) triple differential cross sections for the simultaneous ionization and excitation of helium

    Energy Technology Data Exchange (ETDEWEB)

    Dupre, C.; Lahmam-Bennani, A.; Duguet, A. (Paris-11 Univ., 91-Orsay (France). Lab. des Collisions Atomiques et Moleculaires (France)); Mota-Furtado, F. (Univ. Nova de Lisboa (Portugal). Dept. de Fisica); O' Mahoney, P.F. (Royal Holloway and Bedford New College, Egham (United Kingdom). Dept. of Mathematics); Dal Cappello, C. (Inst. de Physique, Metz (France). Lab. de Physique Moleculaire et des Collisions)

    1992-01-14

    We present absolute triple differential cross sections (TDCS) measurements for ionization of helium leaving the ion in both n = 1 and n = 2 final states, obtained under asymmetric geometry at an incident energy {approx}5.5 keV and ejected electron energies of 5, 10 and 75 eV. The kinematics are chosen to correspond either to a constant ejection energy, or to a constant energy transfer to the target. Angular distributions are measured at both constant ejection angle ({theta}{sub a}mode) and at constant scattering angle ({theta}{sub b} mode). In the {theta}{sub a} mode experiments, the momentum transfer dependence of the n = 2 triple differential generalized oscillator strength is investigated here for the first time. In both modes, the n = 2 angular distributions show several new features which are not present for the n = 1 ones, and which tend to vanish as the ejected energy is increased. They are attributed to final state interactions between the ejected electron and the excited ion. Comparison with first-order theoretical models shows the inadequacy of a Coulomb wave representation of the ejected electron, while in the R-matrix formalism it is found that a five-state multichannel calculation qualitatively describes the shape (but not the amplitude) of the TDCS measured in the {theta}{sub b}mode. Comparison is also made with the photoionization in the dipolar limit where the momentum transfer approaches zero. When integrated over the ejection direction, the double differential generalized oscillator strength ratio for ionization to the n = 1 and n = 2 states in found to agree with a recent first Born close coupling prediction. (author).

  17. Identification of mammalian proteins cross-linked to DNA by ionizing radiation.

    Science.gov (United States)

    Barker, Sharon; Weinfeld, Michael; Zheng, Jing; Li, Liang; Murray, David

    2005-10-07

    Ionizing radiation (IR) is an important environmental risk factor for various cancers and also a major therapeutic agent for cancer treatment. Exposure of mammalian cells to IR induces several types of damage to DNA, including double- and single-strand breaks, base and sugar damage, as well as DNA-DNA and DNA-protein cross-links (DPCs). Little is known regarding the biological consequences of DPCs. Identifying the proteins that become cross-linked to DNA by IR would be an important first step in this regard. We have therefore undertaken a proteomics study to isolate and identify proteins involved in IR-induced DPCs. DPCs were induced in AA8 Chinese hamster ovary or GM00637 human fibroblast cells using 0-4 gray of gamma-rays under either aerated or hypoxic conditions. DPCs were isolated using a recently developed method, and proteins were identified by mass spectrometry. We identified 29 proteins as being cross-linked to DNA by IR under aerated and/or hypoxic conditions. The identified proteins include structural proteins, actin-associated proteins, transcription regulators, RNA-splicing components, stress-response proteins, cell cycle regulatory proteins, and GDP/GTP-binding proteins. The involvement of several proteins (actin, histone H2B, and others) in DPCs was confirmed by using Western blot analysis. The dose responsiveness of DPC induction was examined by staining one-dimensional SDS-polyacrylamide gels with SYPRO Tangerine followed by analysis using fluorescence imaging. Quantitation of the fluorescence signal indicated no significant difference in total yields of IR-induced DPCs generated under aerated or hypoxic conditions, although differences were observed for several individual protein bands.

  18. Photoionization using the xchem approach: Total and partial cross sections of Ne and resonance parameters above the 2 s22 p5 threshold

    Science.gov (United States)

    Marante, Carlos; Klinker, Markus; Kjellsson, Tor; Lindroth, Eva; González-Vázquez, Jesús; Argenti, Luca; Martín, Fernando

    2017-08-01

    The XCHEM approach interfaces well established quantum chemistry packages with scattering numerical methods in order to describe single-ionization processes in atoms and molecules. This should allow one to describe electron correlation in the continuum at the same level of accuracy as quantum chemistry methods do for bound states. Here we have applied this method to study multichannel photoionization of Ne in the vicinity of the autoionizing states lying between the 2 s22 p5 and 2 s 2 p6 ionization thresholds. The calculated total photoionization cross sections are in very good agreement with the absolute measurement of Samson et al. [J. Electron Spectrosc. Relat. Phenom. 123, 265 (2002), 10.1016/S0368-2048(02)00026-9], and with independent benchmark calculations performed at the same level of theory. From these cross sections, we have extracted resonance positions, total autoionization widths, Fano profile parameters, and correlation parameters for the lowest three autoionizing states. The values of these parameters are in good agreement with those reported in earlier theoretical and experimental work. We have also evaluated β asymmetry parameter and partial photoionization cross sections and, from the latter, partial autoionization widths and Starace parameters for the same resonances, not yet available in the literature. Resonant features in the calculated β parameter are in good agreement with the experimental observations. We have found that the three lowest resonances preferentially decay into the 2 p-1ɛ d continuum rather than into the 2 p-1ɛ s one [Phys. Rev. A 89, 043415 (2014), 10.1103/PhysRevA.89.043415], in agreement with previous expectations, and that in the vicinity of the resonances the partial 2 p-1ɛ s cross section can be larger than the 2 p-1ɛ d one, in contrast with the accepted idea that the latter should amply dominate in the whole energy range. These results show the potential of the XCHEM approach to describe highly correlated process

  19. Universal cross sections for K-shell ionization by low-velocity protons; importance of relativistic and energy-loss effects

    International Nuclear Information System (INIS)

    Zander, A.R.; Lapicki, G.

    1981-01-01

    When Z 1 2 , inner-shell ionization of a target atom of atomic number Z 2 by a projectile of atomic number Z 1 occurs predominately via removal of an inner-shell electron to the target atom continuum (direct ionization). Electron capture contributes then insignificantly to the ionization, and thus the predictions of perturbativein-Z 1 /Z 2 theories of direct ionization can be tested through comparison with measured ionization cross sections. We present such a comparison with the recently reported data for K-shell ionization of the Z 2 =22, 26, 28, and 30 elements by 60-150 keV protons (Z 1 =1). These ionization cross sections were inferred from x-ray production measurements using Krause's fluorescence yields

  20. (e,3e) and (e,3-1e) differential cross sections for the double ionization of water molecule

    International Nuclear Information System (INIS)

    Mansouri, A.; Dal Cappello, C.; Kada, I.; Champion, C.; Roy, A.C.

    2009-01-01

    We report new results for differential cross sections for the double ionization of water molecule by 1 keV electron impact. The present calculation is based on the first Born approximation. We describe the water molecule by a single centre wave function of Moccia. For the final state, an approximation of the well-known 3C wave function is used. An extensive study has been made by varying the angles of detection and the energies of each ejected electron. We have investigated the double ionization of each molecular state (1b 1 , 3a 1 , 1b 2 and 2a 1 ) and identified the mechanisms of this process.

  1. Chronic ethanol or nicotine treatment results in partial cross-tolerance between these agents.

    Science.gov (United States)

    Burch, J B; de Fiebre, C M; Marks, M J; Collins, A C

    1988-01-01

    Female DBA/2Ibg mice were treated chronically (21 days) with ethanol- or dextrin-containing liquid diets or infused chronically with nicotine (8 mg/kg/h) or saline for 10 days. The responses of these animals to challenge doses of ethanol (2.5 g/kg) or nicotine (1 or 2 mg/kg) were measured using a test battery consisting of respiration rate, acoustic startle response, Y-maze crosses and rears, heart rate and body temperature. Chronic ethanol-treated animals were tolerant to the effects elicited by a challenge dose of ethanol on four of the six measures and were cross-tolerant to nicotine's effects on the acoustic startle test. Chronic nicotine-treated animals were tolerant to nicotine's effects on five of the six measures and cross-tolerant to ethanol's effects on heart rate and body temperature. Thus, partial cross-tolerance between ethanol and nicotine exists. Chronic nicotine treatment resulted in significant increases in L-[3H]-nicotine binding in six of seven brain regions and in alpha-[125I]-bungarotoxin binding in three of seven brain regions. Chronic ethanol treatment failed to alter the binding of either ligand. Therefore, the cross-tolerance that develops between ethanol and nicotine is not totally dependent on alterations in the number of brain nicotinic receptors.

  2. Photodouble ionization differential cross sections for D2 with various electron energy sharing conditions

    International Nuclear Information System (INIS)

    Seccombe, D.P.; Collins, S.A.; Reddish, T.J.; Selles, P.; Malegat, L.; Huetz, A.; Kazansky, A.K.

    2002-01-01

    The mutual angular distributions of the two ejected electrons following direct photodouble ionization have been measured for D 2 at an excess energy (E) of 25 eV using linearly polarized light. These (γ, 2e) 'triple' differential cross sections (TDCSs) were obtained for asymmetric electron energy conditions with energy sharing ratios (R=E 2 /E 1 ) of R=24, 11.5, 4 and 2.57. In all cases the 'reference' electron (energy = E 1 ) was oriented along the direction of the electric field vector (ε) and detected in coincidence with a second electron (energy = E 2 ) coplanar with ε and the photon beam direction (kγ). For comparison, helium TDCSs were obtained for the same E and R values under nearly identical spectrometer conditions. These show very good agreement with the results of hyperspherical-R-matrix with semi-classical outgoing waves calculations, thus providing even more confidence in the D 2 TDCSs where there is as yet no accurate ab initio theory. The similarities and differences between the experimental results associated with the two targets are qualitatively discussed in terms of Feagin's model (Feagin J M 1998 J. Phys. B: At. Mol. Opt. Phys. 31 L729). (author)

  3. Testing an ionization chamber with gaseous samples and measurements of the (n, alpha) reaction cross sections

    CERN Document Server

    Gledenov, Yu M; Salatskii, V I; Sedyshev, P V; Andrzejewski, J; Szalanski, P

    1999-01-01

    A new ionization chamber with gaseous samples (GIC) has been designed and tested on the thermal and resonance neutron beams of FLNP's neutron sources. The exposed gas volume serves as a target for neutrons. The obtained thermal cross sections for the sup 1 sup 7 O(n, alpha) sup 1 sup 4 C, sup 2 sup 1 Ne(n, alpha) sup 1 sup 8 O and sup 3 sup 6 Ar(n, alpha) sup 3 sup 3 S reactions are (233+-12) mb, (0.18+-0.09) mb and (5.43+-0.27) mb, respectively. These measurements have been performed on a pure beam of thermal neutrons from the high flux reactor IBR-2; and they demonstrated high efficiency and reliability of the method. Compared to samples on substrates, the application of gaseous samples makes the beam background essentially lower, and what is more important, the background component is totally absent due to the absence of Li and B microimpurities in gaseous samples while they do present in the samples on substrates. The method is also applicable to measurements with resonance neutrons. The recovery capabili...

  4. Behavior of partial cross sections and branching ratios in the neighborhood of a resonance

    International Nuclear Information System (INIS)

    Starace, A.F.

    1977-01-01

    Starting from the treatment of Fano for the behavior of the total cross section in a photoionization (or electron-ion scattering) experiment in the vicinity of a resonance, we present a theoretical formula for the behavior of an individual final-state channel in the neighborhood of a resonance. This result is then used to derive another theoretical formula for the behavior of the ratio of two partial cross sections (i.e., the branching ratio) in the vicinity of a resonance. This branching-ratio formula depends on the profile parameters q, GAMMA, and rho 2 for the resonance, on the branching ratio outside the resonance, and on two new parameters which are explicitly related to scattering-matrix elements and phase shifts

  5. How to identify partial exposures to ionizing radiation? Proposal for a cytogenetic method; Como identificar exposicoes parciais as radiacoes ionizantes? Proposta de um metodo citogenetico

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, T.S.; Silva, E.B.; Pinto, M.M.P.L.; Amaral, A., E-mail: thiagosalazar@hotmail.com [Universidade Federal de Pernambuco (LAMBDA/UFPE), Recife, PE (Brazil). Departamento de Energia Nuclear. Lab. de Modelagem e Biodosimetria Aplicada; Lloyd, David [Health Protection Agency, Oxford (United Kingdom). Radiation Protection Division

    2013-08-15

    In cases of radiological incidents or in occupational exposures to ionizing radiation, the majority of exposures are not related to the total body, but only partial. In this context, if the cytogenetic dosimetry is performed, there will be an underestimation of the absorbed dose due to the dilution of irradiated cells with non-irradiated cells. Considering the norms of NR 32 - Safety and Health in the Work of Health Service - which recommends cytogenetic dosimetry in the investigation of accidental exposures to ionizing radiations, it is necessary to develop of a tool to provide a better identification of partial exposures. With this aim, a partial body exposure was simulated by mixing, in vitro, 70% of blood irradiated with 4 Gy of X-rays with 30% of unirradiated blood from the same healthy donor. Aliquots of this mixture were cultured for 48 and 72 hours. Prolonging the time of cell culture from 48 to 72 hours produced no significant change in the yield of dicentrics. However, when only M1 (first division cells) were analyzed, the frequency of dicentrics per cell was increased. Prolonging the time of cell culture allowed cells in mitotic delay by irradiation to reach metaphase, and thus provides enough time for the damage to be visualized. The results of this research present the proposed method as an important tool in the investigation of exposed individuals, allowing associating the cytogenetic analysis with the real percentage of irradiated cells, contributing significantly for the decision making in terms of occupational health. (author)

  6. New approach to analyzing and evaluating cross sections for partial photoneutron reactions

    International Nuclear Information System (INIS)

    Varlamov, V. V.; Ishkhanov, B. S.; Orlin, V. N.

    2012-01-01

    The presence of substantial systematic discrepancies between the results of different experiments devoted to determining cross sections for partial photoneutron reactions—first of all, (γ, n), (γ, 2n), and (γ, 3n) reactions—is a strong motivation for studying the reliability and authenticity of these data and for developing methods for taking into account and removing the discrepancies in question. In order to solve the first problem, we introduce objective absolute criteria involving transitional photoneutron-multiplicity functions F 1 , F 2 , F 3 , …; by definition, their values cannot exceed 1.0, 0.5, 0.33, …, respectively. With the aim of solving the second problem, we propose a new experimental-theoretical approach. In this approach, reaction cross sections are evaluated by simultaneously employing experimental data on the cross section for the total photoneutron yield, σ expt (γ, xn) = σ expt (γ, n) + 2σ expt (γ, 2n) + 3σ expt (γ, 3n) + …, which are free from drawbacks plaguing experimental methods for sorting neutrons in multiplicity, and the results obtained by calculating the functions F theor 1 , F theor 2 , F theor 3 , … on the basis of the modern model of photonuclear reactions. The reliability and authenticity of data on the cross sections for (γ, n), (γ, 2n), and (γ, 3n) partial reactions—σ eval (γ, in) = F i theor σ expt (γ, xn)—were evaluated for the 90 Zr, 115 In, 112,114,116,117,118,119,120,122,124 Sn, 159 Tb, and 197 Au nuclei.

  7. Effects of Coulomb repulsion in the inner-shell ionization cross-section by protons, deuterons and alpha-particles

    International Nuclear Information System (INIS)

    Magno, C.; Milazzo, M.; Pizzi, C.; Porro, F.; Rota, A.; Riccobono, G.

    1979-01-01

    A critical survey has been made of the currently accepted BEA theory for inner-shell atomic-ionization processes. This review has led to the introduction of an effective ion energy which accounts for the slowing-down of the ion in the nuclear Coulomb field. The effect of the ion deflection, also due to the nuclear Coulomb field, is analyzed. Relativistic effects in the collision of ions with K-shell electrons have been taken into account. A tentative qualitative explanation for the experimentally observed nonexistence of a threshold energy for ionization is given in the framework of the BEA theory. Ionization cross-sections for Rb, Sr, Zr, Cd, In, Sb, W by protons in the energy range from 500 keV to 3 MeV have been measured. Also measurements of ionization cross-sections by deuterons in the energy range from 800 keV to 2.6 MeV on Rb, Sr, Zr, Cd, Sb and by He ions in the energy range from 1.4 MeV to 2.8 MeV on Cd and Sb have been performed. Results are compared with those of other authors and in the context of the corrections introduced in the BEA theory. (author)

  8. Composite multilobe descriptors for cross-spectral recognition of full and partial face

    Science.gov (United States)

    Cao, Zhicheng; Schmid, Natalia A.; Bourlai, Thirimachos

    2016-08-01

    Cross-spectral image matching is a challenging research problem motivated by various applications, including surveillance, security, and identity management in general. An example of this problem includes cross-spectral matching of active infrared (IR) or thermal IR face images against a dataset of visible light images. A summary of recent developments in the field of cross-spectral face recognition by the authors is presented. In particular, it describes the original form and two variants of a local operator named composite multilobe descriptor (CMLD) for facial feature extraction with the purpose of cross-spectral matching of near-IR, short-wave IR, mid-wave IR, and long-wave IR to a gallery of visible light images. The experiments demonstrate that the variants of CMLD outperform the original CMLD and other recently developed composite operators used for comparison. In addition to different IR spectra, various standoff distances from close-up (1.5 m) to intermediate (50 m) and long (106 m) are also investigated. Performance of CMLD I to III is evaluated for each of the three cases of distances. The newly developed operators, CMLD I to III, are further utilized to conduct a study on cross-spectral partial face recognition where different facial regions are compared in terms of the amount of useful information they contain for the purpose of conducting cross-spectral face recognition. The experimental results show that among three facial regions considered in the experiments the eye region is the most informative for all IR spectra at all standoff distances.

  9. Doubly differential cross sections of low-energy electrons emitted in the ionization of molecular hydrogen by bare carbon ions

    International Nuclear Information System (INIS)

    Tribedi, L.C.; Richard, P.; Ling, D.; Wang, Y.D.; Lin, C.D.; Moshammer, R.; Kerby, G.W. III; Gealy, M.W.; Rudd, M.E.

    1996-01-01

    We have measured the double differential cross sections (DDCS) (d 2 σ/d var-epsilon ed Ω e ) of low-energy electron emission in the ionization of H 2 bombarded by bare carbon ions of energy 30 MeV. The energy and angular distributions of the electron DDCS have been obtained for 12 different emission angles and for electron energies varying between 0.1 and 300 eV. We have also deduced the single differential and total ionization cross section from the measured DDCS. The data have been compared with the predictions of first Born approximations and the CDW-EIS (continuum distorted wave endash eikonal initial state) model. The CDW-EIS model provides an excellent agreement with the data. copyright 1996 The American Physical Society

  10. Partial Fourier techniques in single-shot cross-term spatiotemporal encoded MRI.

    Science.gov (United States)

    Zhang, Zhiyong; Frydman, Lucio

    2018-03-01

    Cross-term spatiotemporal encoding (xSPEN) is a single-shot approach with exceptional immunity to field heterogeneities, the images of which faithfully deliver 2D spatial distributions without requiring a priori information or using postacquisition corrections. xSPEN, however, suffers from signal-to-noise ratio penalties due to its non-Fourier nature and due to diffusion losses-especially when seeking high resolution. This study explores partial Fourier transform approaches that, acting along either the readout or the spatiotemporally encoded dimensions, reduce these penalties. xSPEN uses an orthogonal (e.g., z) gradient to read, in direct space, the low-bandwidth (e.g., y) dimension. This substantially changes the nature of partial Fourier acquisitions vis-à-vis conventional imaging counterparts. A suitable theoretical analysis is derived to implement these procedures, along either the spatiotemporally or readout axes. Partial Fourier single-shot xSPEN images were recorded on preclinical and human scanners. Owing to their reduction in the experiments' acquisition times, this approach provided substantial sensitivity gains vis-à-vis previous implementations for a given targeted in-plane resolution. The physical origins of these gains are explained. Partial Fourier approaches, particularly when implemented along the low-bandwidth spatiotemporal dimension, provide several-fold sensitivity advantages at minimal costs to the execution and processing of the single-shot experiments. Magn Reson Med 79:1506-1514, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  11. Newly calculated absolute cross-section for the electron-impact ionization of C2H2+

    International Nuclear Information System (INIS)

    Deutsch, H.; Becker, K.; Defrance, P.; Probst, M.; Mark, T.D.; Limtrakul, J.

    2006-01-01

    New measurements of the cross-section for electron impact ionization of the molecular ion C 2 H 2 + have been carried out recently. These data differ significantly from earlier data, because cross-sections corresponding to all the possible dissociative ionization processes were determined. The new data in conjunction with the significant discrepancies between the earlier data and the results of various calculations, which disagreed among themselves by a factor of 3, motivated a renewed attempt to apply the semi-classical Deutsch-Mark (DM) formalism to the calculation of the absolute electron-impact ionization cross-section of this molecular ion. A quantum chemical molecular orbital population analysis for both the neutral molecule and the ion revealed that in the case of C 2 H 2 + the singly occupied molecular orbital (i.e. the 'missing' electron) is highly localized near the site of a C atom in the molecule. This information is explicitly incorporated in our formalism. The results obtained by taking the ionic character directly into account are in excellent agreement with the recent experimental data. (authors)

  12. Partial neutron capture cross sections of actinides using cold neutron prompt gamma activation analysis

    International Nuclear Information System (INIS)

    Genreith, Christoph

    2015-01-01

    Nuclear waste needs to be characterized for its safe handling and storage. In particular long-lived actinides render the waste characterization challenging. The results described in this thesis demonstrate that Prompt Gamma Neutron Activation Analysis (PGAA) with cold neutrons is a reliable tool for the non-destructive analysis of actinides. Nuclear data required for an accurate identification and quantification of actinides was acquired. Therefore, a sample design suitable for accurate and precise measurements of prompt γ-ray energies and partial cross sections of long-lived actinides at existing PGAA facilities was presented. Using the developed sample design the fundamental prompt γ-ray data on 237 Np, 241 Am and 242 Pu were measured. The data were validated by repetitive analysis of different samples at two individual irradiation and counting facilities - the BRR in Budapest and the FRM II in Garching near Munich. Employing cold neutrons, resonance neutron capture by low energetic resonances was avoided during the experiments. This is an improvement over older neutron activation based works at thermal reactor neutron energies. 152 prompt γ-rays of 237 Np were identified, as well as 19 of 241 Am, and 127 prompt γ-rays of 242 Pu. In all cases, both high and lower energetic prompt γ-rays were identified. The most intense line of 237 Np was observed at an energy of E γ =182.82(10) keV associated with a partial capture cross section of σ γ =22.06(39) b. The most intense prompt γ-ray lines of 241 Am and of 242 Pu were observed at E γ =154.72(7) keV with σ γ =72.80(252) b and E γ =287.69(8) keV with σ γ =7.07(12) b, respectively. The measurements described in this thesis provide the first reported quantifications on partial radiative capture cross sections for 237 Np, 241 Am and 242 Pu measured simultaneously over the large energy range from 45 keV to 12 MeV. Detailed uncertainty assessments were performed and the validity of the given uncertainties was

  13. The electron-impact ionization of Ar and Kr revisited: A critical analysis of double-to-single ionization cross section ratio measurements using the fast-atom-beam technique

    International Nuclear Information System (INIS)

    Tarnovsky, V.; Becker, K.

    1992-01-01

    We report new measurements of the absolute electron-impact double ionization cross sections for Ar and Kr and of the ratios of double-to-single ionization for impact energies from threshold to 200 eV using the crossed electron-beam - fast-atom-beam technique. The work was motivated by the recently highlighted spread of about 30% in the Ar 2+ /Ar + ionization cross section ratios obtained by several groups using different experimental techniques. Such a spread is inconsistent with statistical uncertainties of typically 3% or less that were quoted for the various reported ratios. A similar situation exists for Kr where the spread among the recently published Kr 2+ /Kr + ionization cross section ratios is about 15%. We made an attempt to identify all potential systematic errors inherent to the fast-beam technique that could affect the measurement of cross section ratios with special emphasis on those systematic errors that could influence the detection of singly and doubly charged product ions differently. We found Ar 2+ /Ar + and Kr 2+ /Kr + cross section ratios of, respectively 0.066±0.007 and 0.087±0.008 at 100 eV which confirm earlier measurements using the same experimental technique. The error limits on cross sections ratios of multiple-to-single ionization for the same target atom and at least ±10% for ratios of single ionization cross sections for different target species. Our error limits are dominated by systematic uncertainties of the apparatus which do not cancel when cross section ratios are measured, since the ratios are obtained under similar, but not identical experimental conditions. (orig.)

  14. 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

  15. COLLISIONLESS SHOCKS IN A PARTIALLY IONIZED MEDIUM. I. NEUTRAL RETURN FLUX AND ITS EFFECTS ON ACCELERATION OF TEST PARTICLES

    Energy Technology Data Exchange (ETDEWEB)

    Blasi, P.; Morlino, G.; Bandiera, R.; Amato, E. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi, 5, I-50125 Firenze (Italy); Caprioli, D. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08540 (United States)

    2012-08-20

    A collisionless shock may be strongly modified by the presence of neutral atoms through the processes of charge exchange between ions and neutrals and ionization of the latter. These two processes lead to exchange of energy and momentum between charged and neutral particles both upstream and downstream of the shock. In particular, neutrals that suffer a charge exchange downstream with shock-heated ions generate high-velocity neutrals that have a finite probability of returning upstream. These neutrals might then deposit heat in the upstream plasma through ionization and charge exchange, thereby reducing the fluid Mach number. A consequence of this phenomenon, which we refer to as the neutral return flux, is a reduction of the shock compression factor and the formation of a shock precursor upstream. The scale length of the precursor is determined by the ionization and charge-exchange interaction lengths of fast neutrals moving toward upstream infinity. In the case of a shock propagating in the interstellar medium, the effects of ion-neutral interactions are especially important for shock velocities <3000 km s{sup -1}. Such propagation velocities are common among shocks associated with supernova remnants, the primary candidate sources for the acceleration of Galactic cosmic rays. We then investigate the effects of the return flux of neutrals on the spectrum of test particles accelerated at the shock. We find that, for shocks slower than {approx}3000 km s{sup -1}, the particle energy spectrum steepens appreciably with respect to the naive expectation for a strong shock, namely, {proportional_to}E{sup -2}.

  16. Determination of the absolute two-photon ionization cross section of He by an XUV free electron laser

    International Nuclear Information System (INIS)

    Sato, Takahiro; Iwasaki, Atsushi; Ishibashi, Kazuki; Okino, Tomoya; Yamanouchi, Kaoru; Adachi, Junichi; Yagishita, Akira; Yazawa, Hiroki; Aoyma, Makoto; Yabashi, Makina; Nagasono, Mitsuru; Higashiya, Atsushi; Ishikawa, Tetsuya; Kannari, Fumihiko; Yamakawa, Koichi; Midorikawa, Katsumi; Nakano, Hidetoshi

    2011-01-01

    The resonant and non-resonant two-photon single ionization processes of He were investigated using intense free electron laser light in the extreme ultraviolet (XUV) region (53.4-61.4 nm) covering the 1s-2p and 1s-3p resonant transitions of He. On the basis of the dependences of the yield of He + on the XUV light-field intensity at 53.4, 58.4, 56.0 and 61.4 nm, the absolute values of the two-photon ionization cross sections of He at the four different wavelengths and their dependence on the light-field intensity were determined for the first time. (fast track communication)

  17. Partial radiative-recombination cross sections for excited states of hydrogen

    International Nuclear Information System (INIS)

    Fazio, P.M.; Copeland, G.E.

    1985-01-01

    The squares of the dipole and quadrupole matrix elements for the free-to-bound transitions of hydrogen up to bound states Vertical Barn = 20,l = 19> are derived in closed analytic form as a function of the kinetic energy of the free electron. Coulomb wave functions are used for the free as well as the bound states and, thus, the results are good for any electron energy. Several interesting effects are found. First, the transition probabilities are maximum for recombination into specific intermediate-angular-momentum states at low energies (w<1 eV) and where the free-state angular momentum is greater than that of the bound state. Further, that specific intermediate-angular-momentum state depends on the kinetic energy of the free electron. This behavior is in contrast to the ''normal'' behavior of the transition strengths where recombination into s states is greatest and decreases with increasing angular momentum. Second, the quadrupole matrix elements vanish for certain velocities of the free electron. These ''zeros'' produce minima in the corresponding quadrupole cross sections. Finally, the calculated partial cross sections for recombination into high-angular-momentum states are greater when quadrupole transitions are included

  18. Absolute experimental cross sections for the ionization of singly charged barium ions by electron impact: Technical summary report

    International Nuclear Information System (INIS)

    Feeney, R.K.; Hooper, J.W.

    1971-01-01

    The absolute cross sections for the single ionization of Ba + ions by electron impact have been measured as a function of incident electron energy over the electron energy range from below threshold (10.001 eV) to approximately 1000 eV. It is found that the cross section increases from 1.94 x 10 -16 cm 2 to 3.76 x 10 -16 cm 2 between 15.5 and 18 eV actual incident electron energy. This rapid rise is interpreted as the onset of autoionization. Some evidence of structure occurring near the peak of the cross section curve such as found in the isoelectronic system of Cs is observed, but the relative magnitude of the apparent structure is of the same order as the 90% random error confidence limits and thus cannot conclusively be regarded as being present. 56 refs., 16 figs., 7 tabs

  19. Errata and update to ;Experimental cross sections for L-shell X-ray production and ionization by protons;

    Science.gov (United States)

    Miranda, J.; Lapicki, G.

    2018-01-01

    A compilation of experimental L-shell X-ray production and ionization cross sections induced by proton impact was published recently (Miranda and Lapicki, 2014), collecting 15 439 experimental cross sections. The database covers an energy range from 10 keV to 1 GeV, and targets from 10Ne to 95Am. A correction to several tabulated values that were in error, as well as an update including new data published after 2012 and older references not found previously are given in the present work. The updated data base increased the total number of experimental cross sections by 3.1% to 15 921. A new analysis of the total number of experimental points per year shows that the possible saturation in the cumulative total number of data is increased to 15 950 ± 110 points.

  20. Calculations of elastic, ionization and total cross sections for inert gases upon electron impact: threshold to 2 keV

    Energy Technology Data Exchange (ETDEWEB)

    Vinodkumar, Minaxi [V P and R P T P Science College, Vallabh Vidyanagar 388 120, Gujarat (India); Limbachiya, Chetan [P S Science College, Kadi 382 715, Gujarat (India); Antony, Bobby [Department of Environmental, Earth and Atmospheric Sciences, University of Massachusetts Lowell, 265 Riverside Street, Lowell, MA 01854-5045 (United States); Joshipura, K N [Department of Physics, Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat (India)

    2007-08-28

    In this paper we report comprehensive calculations of total elastic (Q{sub el}), total ionization (Q{sub ion}) and total (complete) cross sections (Q{sub T}) for the impact of electrons on inert gases (He, Ne, Ar, Kr and Xe) at energies from about threshold to 2000 eV. We have employed the spherical complex optical potential (SCOP) formalism to evaluate Q{sub el} and Q{sub T} and used the complex spherical potential-ionization contribution (CSP-ic) method to derive Q{sub ion}. The dependence of Q{sub T} on polarizability and incident energy is presented for these targets through an analytical formula. Mutual comparison of various cross sections is provided to show their relative contribution to the total cross sections Q{sub T}. Comparison of Q{sub T} for all these targets is carried out to present a general theoretical picture of collision processes. The present calculations also provide information, hitherto sparse, on the excitation processes of these atomic targets. These results are compared with available experimental and other theoretical data and overall good agreement is observed.

  1. Some of the results of the protection measures in the field of ionizing radiation at FRY border crossings

    International Nuclear Information System (INIS)

    Benderac, R.; Kokotovic, J.; Kolundzija, V.

    2002-01-01

    Full text: SUMMARY: The paper describes some of the results of the protection measures in the field of ionizing radiation at FRY border crossings where there were placed stationary monitors of gamma-radiation. The Institute of Security as licensed institution for ionizing radiation detection, designed and placed stationary devices MZ - 100 at border crossings check points named Kelebija, Horgos, Vatin, Gradina, Presevo, Djeneral Jankovic, Batrovci and the ship lock 'Djerdap-I'. CONCLUSION: Over the several years ago IAEA and its member states as well as other international organizations have become increasingly aware of the consequences which might result from illegal activities involving these materials. Therefore initiatives to strengthen physical protection regime are strongly supported and steps towards improving security of nuclear and other radioactive material have already been taken. Yugoslavia as IAEA member state wishes to contribute to the all together efforts in reducing the possibility of illegal activities such as theft, sabotage and trafficking, involving nuclear materials and other radioactive materials, and on the associated proliferation threat and radiation risks. Therefore relevant national bodies prepare project proposal titled 'PREVENTION OF ILLICIT TRAFFICKING IN NUCLEAR AND RADIOACTIVE MATERIALS IN THE FEDERAL REPUBLIC OF YUGOSLAVIA'. Significant work is ahead in this field, since harmonization of radiological control at our border crossings must be achieved. (author)

  2. On the SCA-description of the energy- and impact parameter dependence of K-shell ionization cross sections

    International Nuclear Information System (INIS)

    Trautmann, D.; Kauer, T.

    1989-01-01

    We present the application of the SCA-model to impact-parameter and energy-dependent K-shell ionization cross sections for several projectile-target combinations. Then we discuss the successes and failures of the SCA-description and investigate the additional approximations still existing in this approach. It is shown that after the introduction of a fully time-dependent perturbed electronic boundstate wave function many of the former discrepancies between experiment and theory can be resolved and in general very good agreement is obtained. (orig.)

  3. Effects of dose and of partial body ionizing radiation on taste aversion learning in rats with lesions of the area postrema

    International Nuclear Information System (INIS)

    Rabin, B.M.; Hunt, W.A.; Lee, J.

    1984-01-01

    The effect of area postrema lesions on the acquisition of a conditioned taste aversion following partial body exposure to ionizing radiation was investigated in rats exposed to head-only irradiation at 100, 200 and 300 rad or to body-only irradiation at 100 and 200 rad. Following head-only irradiation area postrema lesions produced a significant attenuation of the radiation-induced taste aversion at all dose levels, although the rats still showed a significant reduction in sucrose preference. Following body-only exposure, area postrema lesions completely disrupted the acquisition of the conditioned taste aversion. The results are interpreted as indicating that: (a) the acquisition of a conditioned taste aversion following body-only exposure is mediated by the area postrema; and (b) taste aversion learning following radiation exposure to the head-only is mediated by both the area postrema and a mechanism which is independent of the area postrema

  4. Two-dimensional Radiative Magnetohydrodynamic Simulations of Partial Ionization in the Chromosphere. II. Dynamics and Energetics of the Low Solar Atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Sykora, Juan [Bay Area Environmental Research Institute, Petaluma, CA 94952 (United States); Pontieu, Bart De; Hansteen, Viggo H. [Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA 94304 (United States); Carlsson, Mats; Gudiksen, Boris V. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Nóbrega-Siverio, Daniel, E-mail: juanms@lmsal.com [Instituto de Astrofísica de Canarias, E-38200 La Laguna (Tenerife) (Spain)

    2017-09-20

    We investigate the effects of interactions between ions and neutrals on the chromosphere and overlying corona using 2.5D radiative MHD simulations with the Bifrost code. We have extended the code capabilities implementing ion–neutral interaction effects using the generalized Ohm’s law, i.e., we include the Hall term and the ambipolar diffusion (Pedersen dissipation) in the induction equation. Our models span from the upper convection zone to the corona, with the photosphere, chromosphere, and transition region partially ionized. Our simulations reveal that the interactions between ionized particles and neutral particles have important consequences for the magnetothermodynamics of these modeled layers: (1) ambipolar diffusion increases the temperature in the chromosphere; (2) sporadically the horizontal magnetic field in the photosphere is diffused into the chromosphere, due to the large ambipolar diffusion; (3) ambipolar diffusion concentrates electrical currents, leading to more violent jets and reconnection processes, resulting in (3a) the formation of longer and faster spicules, (3b) heating of plasma during the spicule evolution, and (3c) decoupling of the plasma and magnetic field in spicules. Our results indicate that ambipolar diffusion is a critical ingredient for understanding the magnetothermodynamic properties in the chromosphere and transition region. The numerical simulations have been made publicly available, similar to previous Bifrost simulations. This will allow the community to study realistic numerical simulations with a wider range of magnetic field configurations and physics modules than previously possible.

  5. Partially ionized gas flow and heat transfer in the separation, reattachment, and redevelopment regions downstream of an abrupt circular channel expansion.

    Science.gov (United States)

    Back, L. H.; Massier, P. F.; Roschke, E. J.

    1972-01-01

    Heat transfer and pressure measurements obtained in the separation, reattachment, and redevelopment regions along a tube and nozzle located downstream of an abrupt channel expansion are presented for a very high enthalpy flow of argon. The ionization energy fraction extended up to 0.6 at the tube inlet just downstream of the arc heater. Reattachment resulted from the growth of an instability in the vortex sheet-like shear layer between the central jet that discharged into the tube and the reverse flow along the wall at the lower Reynolds numbers, as indicated by water flow visualization studies which were found to dynamically model the high-temperature gas flow. A reasonably good prediction of the heat transfer in the reattachment region where the highest heat transfer occurred and in the redevelopment region downstream can be made by using existing laminar boundary layer theory for a partially ionized gas. In the experiments as much as 90 per cent of the inlet energy was lost by heat transfer to the tube and the nozzle wall.

  6. Correlation of pontic design and partial edentulous areas: A one year cross sectional study

    Directory of Open Access Journals (Sweden)

    Nikzad S.

    2008-12-01

    Full Text Available "nBackground and Aim: By definition, pontic is an artificial replacement of missing tooth (teeth which is essentially used to establish function and esthetics. In order to this fact that, pontic(s is not completely the same as tooth (teeth to be replaced, it may not be concern as a simple type of restoration to achieve the best result, it must be design from the esthetically and hygienically point of view as well as comfort, demand and tissue health of patient. The main purpose of this study is to investigate the pontic designs and their relationship to edentulous partial aras. "nMaterials and Methods: 73 pontics in 57 patients have been included in this cross-sectional study. These patients were under treatment in the department of prosthodontics. A primary cast was achieved from each patient and then the cross-sectional contour of edentulous ridge was depicted. For each patient the type of pontic design was derived from textbook standards and then compared with the design of actual verified Prosthesis at delivery. The shape of tissue surface of each denture was determined by a low viscous impression material. The result of each comparison was recorded in a chart data set. "nResults: The most common pontic design was Modified ridge lap with frequency of 93.2%. The type of ridge was %45.2 normal, %19.2 class I, %8.2 class II and %27.4 class III, respectively. %72.6 of pontics tested have inappropriate design in tissue surface. "nConclusion: It seems that in a high percentage of cases the tissue surface contour of prescribed pontics in department of prosthodontics was incorrect and more attention must be paid to the education of students and technicians.

  7. Analysis of Data on the Cross Sections for Electron-Impact Ionization and Excitation of Electronic States of Atomic Hydrogen (Review)

    Science.gov (United States)

    Shakhatov, V. A.; Lebedev, Yu. A.

    2018-01-01

    A review is given of experimental and theoretical data on the cross sections for ionization, excitation, and deexcitation of atomic hydrogen. The set of the cross sections required to calculate the electron energy distribution function and find the level-to-level rate coefficients needed to solve balance equations for the densities of neutral and charged particles in hydrogen plasma is determined.

  8. Partial and total electronic stopping cross sections of atoms for a singly charged helium ion, Part 2

    International Nuclear Information System (INIS)

    Kaneko, T.; Nishikori, M.; Yamato, N.

    1991-08-01

    Partial and total electronic stopping cross sections of atoms with Z (55 ≤ Z ≤ 92) for a He + ion are tabulated as the second part of NIFS-DATA-11 (1991) on the basis of the wave-packet theory. (author)

  9. Numerical simulation of fuel assembly thermohydraulics of fast reactors with the partial blockage of cross section under the coolant

    International Nuclear Information System (INIS)

    Zhukov, A.V.; Sorokin, A.P.

    2000-01-01

    The problems of numerical modeling of thermohydraulics in assembly of fuel elements of fast reactors with the partial blockage of cross-section under the coolant are considered. The information about existing codes constructed on use of subchannel technique and model of porous body are presented. The results of calculation obtained by these codes are presented. (author)

  10. Petroleomics by electrospray ionization FT-ICR mass spectrometry coupled to partial least squares with variable selection methods: prediction of the total acid number of crude oils.

    Science.gov (United States)

    Terra, Luciana A; Filgueiras, Paulo R; Tose, Lílian V; Romão, Wanderson; de Souza, Douglas D; de Castro, Eustáquio V R; de Oliveira, Mirela S L; Dias, Júlio C M; Poppi, Ronei J

    2014-10-07

    Negative-ion mode electrospray ionization, ESI(-), with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was coupled to a Partial Least Squares (PLS) regression and variable selection methods to estimate the total acid number (TAN) of Brazilian crude oil samples. Generally, ESI(-)-FT-ICR mass spectra present a power of resolution of ca. 500,000 and a mass accuracy less than 1 ppm, producing a data matrix containing over 5700 variables per sample. These variables correspond to heteroatom-containing species detected as deprotonated molecules, [M - H](-) ions, which are identified primarily as naphthenic acids, phenols and carbazole analog species. The TAN values for all samples ranged from 0.06 to 3.61 mg of KOH g(-1). To facilitate the spectral interpretation, three methods of variable selection were studied: variable importance in the projection (VIP), interval partial least squares (iPLS) and elimination of uninformative variables (UVE). The UVE method seems to be more appropriate for selecting important variables, reducing the dimension of the variables to 183 and producing a root mean square error of prediction of 0.32 mg of KOH g(-1). By reducing the size of the data, it was possible to relate the selected variables with their corresponding molecular formulas, thus identifying the main chemical species responsible for the TAN values.

  11. Induction of DNA–protein cross-links by ionizing radiation and their elimination from the genome

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Toshiaki; Mitsusada, Yusuke [Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Salem, Amir M.H. [Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Department of Pathology, Medical Research Division, National Research Centre, El-Bohouth St., Dokki, Giza 12311 (Egypt); Shoulkamy, Mahmoud I. [Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Department of Zoology, Biological Science Building, Faculty of Science, Minia University, Minia 61519 (Egypt); Sugimoto, Tatsuya [Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Hirayama, Ryoichi; Uzawa, Akiko [Research Center for Charged Particle Therapy, National Institute of Radiological Sciences (NIRS), Chiba 263-8555 (Japan); Furusawa, Yoshiya [Development and Support Center, National Institute of Radiological Sciences (NIRS), Chiba 263-8555 (Japan); Ide, Hiroshi, E-mail: ideh@hiroshima-u.ac.jp [Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan)

    2015-01-15

    Highlights: • Normoxic and hypoxic mouse tumors were irradiated with X-rays and C-ion beams. • DNA–protein cross-links (DPCs) and DNA double-strand breaks (DSBs) were analyzed. • C-ion beams produced more DPCs than did X-rays in normoxic and hypoxic tumor cells. • DPCs were eliminated from the genome much more slowly than DSBs. • Persisting DPCs may have deleterious effects on cells in conjunction with DSBs. - Abstract: Ionizing radiation produces various types of DNA lesions, such as base damage, single-strand breaks, double-strand breaks (DSBs), and DNA–protein cross-links (DPCs). Of these, DSBs are the most critical lesions underlying the lethal effects of ionizing radiation. With DPCs, proteins covalently trapped in DNA constitute strong roadblocks to replication and transcription machineries, and hence can be lethal to cells. The formation of DPCs by ionizing radiation is promoted in the absence of oxygen, whereas that of DSBs is retarded. Accordingly, the contribution of DPCs to the lethal events in irradiated cells may not be negligible for hypoxic cells, such as those present in tumors. However, the role of DPCs in the lethal effects of ionizing radiation remains largely equivocal. In the present study, normoxic and hypoxic mouse tumors were irradiated with X-rays [low linear energy transfer (LET) radiation] and carbon (C)-ion beams (high LET radiation), and the resulting induction of DPCs and DSBs and their removal from the genome were analyzed. X-rays and C-ion beams produced more DPCs in hypoxic tumors than in normoxic tumors. Interestingly, the yield of DPCs was slightly but statistically significantly greater (1.3- to 1.5-fold) for C-ion beams than for X-rays. Both X-rays and C-ion beams generated two types of DPC that differed according to their rate of removal from the genome. This was also the case for DSBs. The half-lives of the rapidly removed components of DPCs and DSBs were similar (<1 h), but those of the slowly removed components

  12. Electron Impact Ionization of C60

    International Nuclear Information System (INIS)

    Duenser, B.; Lezius, M.; Scheier, P.; Deutsch, H.; Maerk, T.D.

    1995-01-01

    Absolute partial and total cross sections for the electron impact ionization of C 60 have been measured using a novel approach for the absolute calibration. The results obtained reveal not only an anomalous large parent ion cross section (as compared to the other ionization channels), but also anomalies for the production of multiply charged parent and fragment ions. This special behavior has its origin in the specific electronic and geometric structure of C 60 . Semiclassical calculations for singly charged ions support the measured data

  13. Triple differential cross section for the near threshold single ionization of helium atoms for equal energy sharing

    Energy Technology Data Exchange (ETDEWEB)

    Purohit, G., E-mail: ghanshyam.purohit@spsu.ac.in [Department of Physics, School of Engineering, Sir Padampat Singhania University, Bhatewar, Udaipur 313 601 (India); Singh, P. [Department of Physics, School of Engineering, Sir Padampat Singhania University, Bhatewar, Udaipur 313 601 (India); Dorn, A.; Ren, X. [Max Planck Institute for Nuclear Physics, 69117 Heidelberg (Germany); Patidar, V. [Department of Physics, School of Engineering, Sir Padampat Singhania University, Bhatewar, Udaipur 313 601 (India)

    2016-05-15

    Highlights: • Present paper describes electron impact single ionization of helium atoms near threshold. • This energy range provided challenges to theoretical models due to presence of several physical effects at low energies such as second order processes, PCI, polarization, etc. • Inclusion of second Born term and target polarization is helpful to analyze the measurements. • Present paper also describes usefulness of post collisional interaction in the collision dynamics at low energies. - Abstract: Low energy electron impact single ionization triple differential cross section (TDCS) results are reported for the helium atoms in the threshold regime at 1 eV, 3 eV and 5 eV excess energy. TDCSs are calculated in the doubly symmetric kinematics for the coplanar to perpendicular emission of electrons. Present attempt to calculate TDCS in the second Born approximation and treating target polarization and post collision interaction is helpful to analyze the available measurements. The second order processes, target polarization and post collision interaction (PCI) have been found to be significant in describing the trends of TDCS and helpful to produce reasonably good agreement with measurements.

  14. Triple differential cross section for the near threshold single ionization of helium atoms for equal energy sharing

    International Nuclear Information System (INIS)

    Purohit, G.; Singh, P.; Dorn, A.; Ren, X.; Patidar, V.

    2016-01-01

    Highlights: • Present paper describes electron impact single ionization of helium atoms near threshold. • This energy range provided challenges to theoretical models due to presence of several physical effects at low energies such as second order processes, PCI, polarization, etc. • Inclusion of second Born term and target polarization is helpful to analyze the measurements. • Present paper also describes usefulness of post collisional interaction in the collision dynamics at low energies. - Abstract: Low energy electron impact single ionization triple differential cross section (TDCS) results are reported for the helium atoms in the threshold regime at 1 eV, 3 eV and 5 eV excess energy. TDCSs are calculated in the doubly symmetric kinematics for the coplanar to perpendicular emission of electrons. Present attempt to calculate TDCS in the second Born approximation and treating target polarization and post collision interaction is helpful to analyze the available measurements. The second order processes, target polarization and post collision interaction (PCI) have been found to be significant in describing the trends of TDCS and helpful to produce reasonably good agreement with measurements.

  15. Fully differential cross sections for Li2+-impact ionization of Li(2s) and Li(2p)

    Science.gov (United States)

    Ghorbani, Omid; Ghanbari-Adivi, Ebrahim; Fabian Ciappina, Marcelo

    2018-05-01

    A semiclassical impact parameter version of the continuum distorted wave-Eikonal initial state theory is developed to study the differential ionization of Li atoms in collisions with Li2+ ions. Both post and prior forms of the transition amplitude are considered. The fully differential cross sections are calculated for the lithium targets in their ground and their first excited states and for the projectile ions at 16 MeV impact energy. The role of the inter-nuclear interaction as well as the significance of the post-prior discrepancy in the ejected electron spectra are investigated. The obtained results for ejection of the electron into the azimuthal plane are compared with the recent measurements and with their corresponding values obtained using a fully quantum mechanical version of the theory. In most of the cases, the consistency of the present approach with the experimental and the quantum theoretical data is reasonable. However, for 2p-state ionization, in the cases where no experimental data exist, there is a considerable difference between the two theoretical approaches. This difference is questionable and further experiments are needed to judge which theory makes a more accurate description of the collision dynamics.

  16. Ionization of liquid water by fast electron impact: multiple differential cross sections for the 1B1 orbital

    International Nuclear Information System (INIS)

    Fojon, O A; De Sanctis, M L; Stia, C R; Vuilleumier, R; Politis, M-F

    2011-01-01

    We present a theoretical study of single ionization of water molecules in liquid phase by impact of fast electrons in a coplanar geometry. Multiple differential cross sections are obtained through a first order model obtained within the framework of an independent electron approximation in which relaxation of the target is not taken into account. The wavefunctions for a single water molecule in the liquid phase are obtained through a Wannier orbital formalism and the ejected electron is described by means of Coulomb functions. We also present averaged calculations over all molecular orientations. A comparison with previous theoretical and experimental results, the latter corresponding to water in gaz phase, shows a good agreement. The main physical features of the reaction (such as binary and recoil peaks) present in measurements for vapor are also observed in the present theoretical predictions.

  17. Application of the binary-encounter theory to proton impact double ionization of atoms. [Cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A; Roy, B N [Bihar Univ. (India). Dept. of Physics

    1977-10-21

    Proton impact double ionisation of He has been investigated in the double-encounter model of Gryzinski (Phys. Rev.; 138A:305, 322 and 336 (1965)). The binary-encounter expressions developed by Vriens (Proc. Phys. Soc.; 89:13 (1966), Ibid 90:935 (1967)) along with an accurate quantum-mechanical velocity distribution for the bound electrons in both encounters have been used to obtain double-ionisation cross sections. These results have been compared with the experimental observations and earlier calculations by Gryzinski's method. The variation of sigmasub(+)/sigmasub(++) (single-ionisation cross section/double-ionisation cross section) with incident proton energy is also found to be in qualitative agreement with the experimentally observed variation.

  18. Thick-target method in the measurement of inner-shell ionization cross-sections by low-energy electron impact

    International Nuclear Information System (INIS)

    An, Z.; Wu, Y.; Liu, M.T.; Duan, Y.M.; Tang, C.H.

    2006-01-01

    In this paper, we have studied the thick-target method for the measurements of atomic inner-shell ionization cross-section or X-ray production cross-section by keV electron impact. We find that in the processes of electron impact on the thick targets, the ratios of the characteristic X-ray yields of photoelectric ionization by bremsstrahlung to the total characteristic X-ray yields are Z-dependent and shell-dependent, and the ratios also show the weak energy-dependence. In addition, in the lower incident energy region (i.e. U < 5-6), the contribution from the rediffusion effect and the secondary electrons can be negligible. In general, the thick-target method can be appropriately applied to the measurements of atomic inner-shell ionization cross-sections or X-ray production cross-sections by electron impact for low and medium Z elements in the lower incident electron energy (i.e. U < 5-6). The experimental accuracies by the thick-target method can reach to the level equivalent or superior to the accuracies of experimental data based on the thin-target method. This thick-target method has been applied to the measurement of K-shell ionization cross-sections of Ni element by electron impact in this paper

  19. Triple differential cross-sections for the ionization of metastable 2P ...

    Indian Academy of Sciences (India)

    2016-10-06

    Oct 6, 2016 ... Precise calculation of different types of cross-sections, such as ... our earlier methods on the hydrogenic 2S-state ioniza- tion results [35] is ... shows interesting qualitative fitness with the hydrogen- ..... area of research. There is ...

  20. A review of experimental L-shell ionization cross sections for light ion impact

    International Nuclear Information System (INIS)

    Orlic, I.

    1994-01-01

    More than 20 000 experimental L-shell cross sections data points for light ion impact are presently available. This number of data provides a solid ground for detailed statistical analysis and comparison with theoretical predictions. An overview of all available experimental data is given in this work. Discussed are annual growth and decline of published data, distribution of L-shell cross section data vs. target atomic number as well as distribution of number of data vs. incident ions. Data for proton impact were recently tabulated by this group and compared with the ECPSSR theoretical predictions in a usual manner: by plotting ratio S = σ exper. /σ theory vs. reduced velocity parameter for each individual subshell L1, L2 and L3, and separately for three groups of target atomic numbers. After applying statistical procedure recommended by the Particle Data Group, so called open-quotes reference cross sectionsclose quotes for proton impact were obtained. Statistical errors of reference cross sections obtained in such a way were significantly smaller than errors of individual experimental results which allowed for some generalization and comparison with theoretical predictions. A review of obtained results is presented in this work

  1. Singly differential electron emission cross sections for ionization of helium by protons

    International Nuclear Information System (INIS)

    Barna, I.F.; Gagyi-Palffy, A.C.; Gulyas, L.; Tokesi, K.; Burgdoerfer, J.

    2005-01-01

    Angular differential cross sections are calculated for electrons emitted in proton-helium collisions within the framework of the time-dependent coupled channel-method. The channel wave functions are constructed from Slater functions and Coulomb wave packets. As projectiles we consider protons with energies between 0.3 and 1.5 MeV. We compare our results with experimental data and other theoretical calculations using the first Born approximation, different distorted wave models and classical trajectory Monte Carlo simulations

  2. Measurement and calculation of excitation cross sections and level ionization by electron impact

    International Nuclear Information System (INIS)

    Blanco Rames, F.

    1990-01-01

    The experimental and theoretical study of the atomic structure in neutral noble gases is studied in this work. It mainly deals with the determination of total cross sections by electron impact and transition probabilities, including: Chapter 1: Theoretical introduction and the intermediate coupling description obtained for 420 levels of s, p and d configurations in neutral noble gases. Chapter 2: Experimental and theoretical values for electron collision cross sections are obtained for several levels of He, Ne, Ar and Kr. Our results as well as those available from existing bibliography are sumarized and compared. By means of an intermediate coupling treatment a number of regularities is found that provides us with some useful approximate semi empirical expressions. Chapter 3: Determination of lifetime and transition probabilities. Lifetime measurements are carried out by means of laser excitation and multichannel delayed coincidences technique. The experimental setup and electronics are also described. Chapter 4: Details the experimental setup developed for electron cross sections measurement by the optical method. The difficulties of this method and their treatment are also shown. (Author)

  3. First results of total and partial cross-section measurements of the 107Ag(p,γ)108Cd reaction

    Science.gov (United States)

    Heim, Felix; Mayer, Jan; Scholz, Philipp; Spieker, Mark; Zilges, Andreas

    2018-01-01

    The γ process is assumed to play an important role in the nucleosynthesis of the majority of the p nuclei. Since the network of the γ process includes so many different reactions and - mainly unstable - nuclei, cross-section values are predominantly calculated in the scope of the Hauser-Feshbach statistical model. The values heavily depend on the nuclear-physics input parameters. The results of total and partial cross-section measurements are used to improve the accuracy of the theoretical calculations. In order to extend the experimental database, the 107Ag(p,γ)108Cd reaction was studied via the in-beam method at the high-efficiency HPGe γ-ray spectrometer HORUS at the University of Cologne. Proton beams with energies between 3.5 MeV and 5.0 MeV were provided by the 10 MV FN-Tandem accelerator leading to the determination of four new total cross-section values. After slight adjustments of the nuclear level density and γ-ray strength function an excellent agreement between theoretical calculations and experimentally deduced values for both total and partial cross sections has been obtained.

  4. Ionization and charge exchange in atom collision with multicharged ion

    International Nuclear Information System (INIS)

    Presnyakov, L.P.; Uskov, D.B.

    1984-01-01

    Single-electron ionization and charge exchange are considered in collisions of an atom with an ion of charge Z> or =3 and at velocities v>Z -1 /sup // 3 . The approach is based on the Keldysh quasiclassical method. The ionization and charge exchange processes are described within the framework of a single formalism. Effects of rotation and translation are taken into account. The calculated total and partial cross sections agree well with the available experimental data. OFF

  5. Hybrid Quantum Mechanical-Quasi-Classical Model for Evaluating Ionization and Stripping Cross Sections in Atom-Ion Collisions

    CERN Document Server

    Kaganovich, I D; Startsev, E

    2005-01-01

    Ion-atom ionization cross sections are needed in many applications employing the propagation of fast ions through matter. When experimental data or full-scale theoretical calculations are non-existent, approximate methods must be used. The most robust and easy-to-use approximations include the Born approximation of quantum mechanics and the quasi-classical approach utilizing classical mechanics together with the Bohr-Sommerfeld quantization rule.* The simplest method to extend the validity of both approaches is to combine them, i.e., use the two different approaches but only for the regions of impact parameters in which they are valid, and sum the results to obtain the total cross section. We have recently investigated theoretically and experimentally the stripping of more than 18 different pairs of projectile and target atoms in the range of 3-38 MeV/amu to study the range of validity of various approximations. The results of the modified approach agree better with the experimental data than either the Born ...

  6. Coplanar asymmetric angles and symmetric energy sharing triple differential cross sections for 200 eV electron-impact ionization of Ar (3p)

    International Nuclear Information System (INIS)

    Ozer, Zehra N; Varol, Onur; Yavuz, Murat; Dogan, Mevlut; Amami, Sadek; Madison, Don

    2015-01-01

    We have measured triple differential cross sections (TDCSs) for electron-impact ionization of the 3p shell of Ar at 200 eV incident electron energy. The experiments have been performed in coplanar asymmetric energy sharing geometry. The experimental results are compared with the theoretical models of three body distorted wave (3DW) and distorted wave Born approximation (DWBA). (paper)

  7. WE-E-BRE-11: New Method to Simulate DNA Damage Using Ionization Cross-Sections and a Geometrical Nucleosome Model

    International Nuclear Information System (INIS)

    Pater, P; Seuntjens, J; El Naqa, I

    2014-01-01

    Purpose: To obtain probability distributions of various DNA damage types as a function of the incident electron kinetic energy. Methods: Using Geant4-DNA electron ionization cross-sections, we calculated path length distributions for electrons of energies between 10 eV and 1 MeV, defined as the length between two subsequent interactions. These path lengths were then convolved with probability distributions for the creation of same-strand damage, opposite-strand damage, clustered damage, isolated damage, and same DNA strand target damage. These probability distributions of DNA damage were obtained by a Monte Carlo routine calculating probabilities of interaction in DNA targets inside a nucleosome geometrical model. Results represent the probability of a secondary electron, initially created inside a DNA strand target, of undergoing its next interaction: (1) in the opposite strand (DSB), (2) in the same strand (SSB+), (3) in either the opposite or same-strand (clustered), (4) in the same DNA target (multiple-hit) or (5) more than 10 base pairs away (isolated). Results: Electrons with kinetic energy between 50 and 250 eV have a maximal probability of creating DSB, SSB+, clustered damage and multiple-hits in the same target The probabilities for these damage patterns have values of 2.5%, 4.3%, 6.7% and 5.4%, respectively. Isolated damage is most probable between 700 eV to 900 eV with a probability of 0.2%. Conclusion: We obtained DNA damage probability distributions as a function of electron incident energy. We showed that electrons with kinetic energies between 50 and 250 eV have the highest probability of producing complex forms of DNA damage (DSB, SSB+). We also showed that a double ionization within the same DNA target is the most frequent outcome occurring 5% of the time. It is expected that electron slowing down spectra can be convolved with our formalism to calculate source specific DNA damage patterns. Research grants from governments of Canada and Quebec. PP

  8. Triple-differential cross sections for target ionization with simultaneous projectile detachment in 200-keV H-+He collisions

    International Nuclear Information System (INIS)

    Ferger, T.; Najjari, B.; Moshammer, R.; Ullrich, J.; Schulz, M.; Fischer, D.

    2007-01-01

    We have performed a kinematically complete experiment for target ionization with simultaneous projectile detachment (TIPD) in 200-keV H - +He collisions. From the data we extracted triple-differential cross sections (TDCSs) for each electron separately. These TDCSs closely resemble corresponding data for single ionization by charged-particle impact. Surprisingly, the contributions from higher-order processes to TIPD, proceeding through two independent interactions of each electron with the core of the respective other collision partner, are found to be somewhat larger than the first-order process proceeding through the electron-electron interaction

  9. Comparison Of Quantum Mechanical And Classical Trajectory Calculations Of Cross Sections For Ion-Atom Impact Ionization of Negative - And Positive -Ions For Heavy Ion Fusion Applications

    International Nuclear Information System (INIS)

    Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.

    2003-01-01

    Stripping cross sections in nitrogen have been calculated using the classical trajectory approximation and the Born approximation of quantum mechanics for the outer shell electrons of 3.2GeV I - and Cs + ions. A large difference in cross section, up to a factor of six, calculated in quantum mechanics and classical mechanics, has been obtained. Because at such high velocities the Born approximation is well validated, the classical trajectory approach fails to correctly predict the stripping cross sections at high energies for electron orbitals with low ionization potential

  10. Electron-impact-ionization dynamics of S F6

    Science.gov (United States)

    Bull, James N.; Lee, Jason W. L.; Vallance, Claire

    2017-10-01

    A detailed understanding of the dissociative electron ionization dynamics of S F6 is important in the modeling and tuning of dry-etching plasmas used in the semiconductor manufacture industry. This paper reports a crossed-beam electron ionization velocity-map imaging study on the dissociative ionization of cold S F6 molecules, providing complete, unbiased kinetic energy distributions for all significant product ions. Analysis of these distributions suggests that fragmentation following single ionization proceeds via formation of S F5 + or S F3 + ions that then dissociate in a statistical manner through loss of F atoms or F2, until most internal energy has been liberated. Similarly, formation of stable dications is consistent with initial formation of S F4 2 + ions, which then dissociate on a longer time scale. These data allow a comparison between electron ionization and photoionization dynamics, revealing similar dynamical behavior. In parallel with the ion kinetic energy distributions, the velocity-map imaging approach provides a set of partial ionization cross sections for all detected ionic fragments over an electron energy range of 50-100 eV, providing partial cross sections for S2 +, and enables the cross sections for S F4 2 + from S F+ to be resolved.

  11. Partial gamma-ray cross section measurements in 109Ag(n, x n y p gamma) reactions

    Energy Technology Data Exchange (ETDEWEB)

    Fotiadis, Nikolaos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Devlin, Matthew James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nelson, Ronald Owen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carroll, James [US Army Research Laboratory, Adelphi, MD (United States)

    2015-06-02

    We report on absolute partial cross sections for production of discrete γ-rays using 109Ag(n, xnypγ) reactions with x ≤ 7 and y ≤ 1 in a total of 12 reaction channels. The data were taken using the GEANIE spectrometer comprised of 20 high-purity Ge detectors with 20 BGO escape-suppression shields. The broad-spectrum pulsed neutron beam of the Los Alamos Neutron Science Center’s (LANSCE) WNR facility provided neutrons in the energy range from 0.2 to 300 MeV. The time-of- flight technique was used to determine the incident neutron energies. Partial γ-ray cross sections have been measured for a total of 109 transitions and for neutron energies 0.8 MeV< En<300 MeV. An estimate of the population of isomers in the (n, n'), (n, 2n) and (n, 3n) channels was made.

  12. Absolute cross section measurement for the ionization of the K-shell of titanium and nickel by electron impact (50 KEV)

    International Nuclear Information System (INIS)

    Jessenberger, J.

    1974-01-01

    The yield of characteristic X-ray K radiation of titanium during bombardment with electrons in the energy region of 6-50 keV and of nickel at 9-50 keV was measured, and the cross sections for th ionization of the K shell of titanium and nickel were determined from this. The results obtained are compared with several theoretical models. (WL/LN) [de

  13. Kinetics of gravity-driven slug flow in partially wettable capillaries of varying cross section

    Science.gov (United States)

    Nissan, Alon; Wang, Qiuling; Wallach, Rony

    2016-11-01

    A mathematical model for slug (finite liquid volume) motion in not-fully-wettable capillary tubes with sinusoidally varying cross-sectional areas was developed. The model, based on the Navier-Stokes equation, accounts for the full viscous terms due to nonuniform geometry, the inertial term, the slug's front and rear meniscus hysteresis effect, and dependence of contact angle on flow velocity (dynamic contact angle). The model includes a velocity-dependent film that is left behind the advancing slug, reducing its mass. The model was successfully verified experimentally by recording slug movement in uniform and sinusoidal capillary tubes with a gray-scale high-speed camera. Simulation showed that tube nonuniformity has a substantial effect on slug flow pattern: in a uniform tube it is monotonic and depends mainly on the slug's momentary mass/length; an undulating tube radius results in nonmonotonic flow characteristics. The static nonzero contact angle varies locally in nonuniform tubes owing to the additional effect of wall slope. Moreover, the nonuniform cross-sectional area induces slug acceleration, deceleration, blockage, and metastable-equilibrium locations. Increasing contact angle further amplifies the geometry effect on slug propagation. The developed model provides a modified means of emulating slug flow in differently wettable porous media for intermittent inlet water supply (e.g., raindrops on the soil surface).

  14. 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

  15. Dynamics of the helium atom close to the full fragmentation threshold: Ionization excitation

    International Nuclear Information System (INIS)

    Bouri, C.; Selles, P.; Malegat, L.; Teuler, J.M.; Njock, M. Kwato; Kazansky, A.K.

    2005-01-01

    The hyperspherical R-matrix method with semiclassical outgoing waves, designed to provide accurate double-ionization cross sections, is extended to allow for the computation of ionization-excitation data of comparable quality. Accordingly, it appears now as a complete method for treating the correlated dynamics of two-electron atoms, in particular above their full fragmentation threshold. Cross sections σ n and asymmetry parameters β n are obtained for single photoionization of helium with excitation of the residual ion up to as high a level as n=50 at 0.1 eV above the double-ionization threshold. These data are extrapolated to infinite values of n in order to check widespread assumptions regarding this limit. Our data are found consistent with the assumed n -3 dependence of the partial ionization cross sections. However, the β ∞ =-0.636 obtained still lies far from the -1 value expected at the double-ionization threshold

  16. Ionization cross sections of the Au L subshells by electron impact from the L3 threshold to 100 keV

    Science.gov (United States)

    Barros, Suelen F.; Vanin, Vito R.; Maidana, Nora L.; Martins, Marcos N.; García-Alvarez, Juan A.; Santos, Osvaldo C. B.; Rodrigues, Cleber L.; Koskinas, Marina F.; Fernández-Varea, José M.

    2018-01-01

    We measured the cross sections for Au Lα, Lβ, Lγ, Lℓ and Lη x-ray production by the impact of electrons with energies from the L3 threshold to 100 keV using a thin Au film whose mass thickness was determined by Rutherford Backscattering Spectrometry. The x-ray spectra were acquired with a Si drift detector, which allowed to separate the components of the Lγ multiplet lines. The measured Lα, Lβ, {{L}}{γ }1, L{γ }{2,3,6}, {{L}}{γ }{4,4\\prime }, {{L}}{γ }5, {{L}}{\\ell } and Lη x-ray production cross sections were then employed to derive Au L1, L2 and L3 subshell ionization cross sections with relative uncertainties of 8%, 7% and 7%, respectively; these figures include the uncertainties in the atomic relaxation parameters. The correction for the increase in electron path length inside the Au film was estimated by means of Monte Carlo simulations. The experimental ionization cross sections are about 10% above the state-of-the-art distorted-wave calculations.

  17. Influence of Triply-Charged Ions and Ionization Cross-Sections in a Hybrid-PIC Model of a Hall Thruster Discharge

    Science.gov (United States)

    Smith, Brandon D.; Boyd, Iain D.; Kamhawi, Hani

    2014-01-01

    The sensitivity of xenon ionization rates to collision cross-sections is studied within the framework of a hybrid-PIC model of a Hall thruster discharge. A revised curve fit based on the Drawin form is proposed and is shown to better reproduce the measured crosssections at high electron energies, with differences in the integrated rate coefficients being on the order of 10% for electron temperatures between 20 eV and 30 eV. The revised fit is implemented into HPHall and the updated model is used to simulate NASA's HiVHAc EDU2 Hall thruster at discharge voltages of 300, 400, and 500 V. For all three operating points, the revised cross-sections result in an increase in the predicted thrust and anode efficiency, reducing the error relative to experimental performance measurements. Electron temperature and ionization reaction rates are shown to follow the trends expected based on the integrated rate coefficients. The effects of triply-charged xenon are also assessed. The predicted thruster performance is found to have little or no dependence on the presence of triply-charged ions. The fraction of ion current carried by triply-charged ions is found to be on the order of 1% and increases slightly with increasing discharge voltage. The reaction rates for the 0?III, I?III, and II?III ionization reactions are found to be of similar order of magnitude and are about one order of magnitude smaller than the rate of 0?II ionization in the discharge channel.

  18. Electron-Impact Ionization Cross Sections of H, He, N, O, Ar, Xe, Au, Pb Atoms and Their Ions in the Electron Energy Range from the Threshold up to 200 keV

    CERN Document Server

    Povyshev, V M; Shevelko, V P; Shirkov, G D; Vasina, E G; Vatulin, V V

    2001-01-01

    Single electron-impact ionization cross sections of H, He, N, O, Ar, Xe, Au, Pb atoms and their positive ions (i.e. all ionization stages) are presented in the electron energy range from the threshold up to 200 keV. The data-set for the cross sections has been created on the basis of available experimental data and calculations performed by the computer code ATOM. Consistent data for the ionization cross sections have been fitted by seven parameters using the LSM method. The accuracy of the calculated data presented is within a factor of 2 that in many cases is sufficient to solve the plasma kinetics problems. Contributions from excitation-autoionization and resonant-ionization processes as well as ionization of atoms and ions are not considered here. The results of the numerical calculations are compared with the well-known Lotz formulae for ionization of neutral atoms and positive ions. The material is illustrated by figures and includes tables of ionization cross sections, binding energies and fitting para...

  19. Impact on smoking of England's 2012 partial tobacco point of sale display ban: a repeated cross-sectional national study.

    Science.gov (United States)

    Kuipers, Mirte A G; Beard, Emma; Hitchman, Sara C; Brown, Jamie; Stronks, Karien; Kunst, Anton E; McNeill, Ann; West, Robert

    2017-03-01

    A partial tobacco point of sale (PoS) display ban was introduced in large shops (>280 m 2 floor area) in England on 6 April 2012. The aim of this study was to assess the medium-term effects of the partial tobacco PoS display ban on smoking in England. Data were used from 129 957 respondents participating in monthly, cross-sectional household surveys of representative samples of the English adult population aged 18+ years from January 2009 to February 2015. Interrupted-time series regression models assessed step changes in the level of current smoking and cigarette consumption in smokers and changes in the trends postban compared with preban. Models were adjusted for sociodemographic variables and e-cigarette use, seasonality and autocorrelation. Potential confounding by cigarette price was accounted for by time, as price was almost perfectly correlated with time. Following the display ban, there was no immediate step level change in smoking (-3.69% change, 95% CI -7.94 to 0.75, p=0.102) or in cigarette consumption (β -0.183, 95% CI -0.602 to 0.236). There was a significantly steeper decline in smoking post display ban (-0.46% change, 95% CI -0.72 to -0.20, p=0.001). This effect was demonstrated by respondents in manual occupations (-0.62% change, 95% CI -0.72 to -0.20, p=0.001), but not for those in non-manual occupations (-0.42, 95% CI -0.90 to 0.06, p=0.084). Cigarette consumption declined preban period (β -0.486, 95% CI -0.633 to -0.339, p<0.001), but no significant change in cigarette consumption trend was observed (β 0.019, 95% CI -0.006 to 0.042, p=0.131). The partial tobacco PoS display ban introduced in England in April 2012 did not lead to an immediate decline in smoking, but was followed by a decline in the trend of smoking prevalence that could not be accounted for by seasonal factors, e-cigarette use or price changes. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  20. Comparison of two equation-of-state models for partially ionized aluminum: Zel'dovich and Raizer's model versus the activity expansion code

    Science.gov (United States)

    Harrach, Robert J.; Rogers, Forest J.

    1981-09-01

    Two equation-of-state (EOS) models for multipy ionized matter are evaluated for the case of an aluminum plasma in the temperature range from about one eV to several hundred eV, spanning conditions of weak to strong ionization. Specifically, the simple analytical mode of Zel'dovich and Raizer and the more comprehensive model comprised by Rogers' plasma physics avtivity expansion code (ACTEX) are used to calculate the specific internal energy ɛ and average degree of ionization Z¯*, as functons of temperature T and density ρ. In the absence of experimental data, these results are compared against each other, covering almost five orders-of-magnitude variation in ɛ and the full range of Z¯* We find generally good agreement between the two sets of results, especially for low densities and for temperatures near the upper end of the rage. Calculated values of ɛ(T) agree to within ±30% over nearly the full range in T for densities below about 1 g/cm3. Similarly, the two models predict values of Z¯*(T) which track each other fairly well; above 20 eV the discrepancy is less than ±20% fpr ρ≲1 g/cm3. Where the calculations disagree, we expect the ACTEX code to be more accurate than Zel'dovich and Raizer's model, by virtue of its more detailed physics content.

  1. Comparison of two equation-of-state models for partially ionized aluminum: Zel'dovich and Raizer's model versus the activity expansion code

    Energy Technology Data Exchange (ETDEWEB)

    Harrach, R.J.; Rogers, F.J.

    1981-09-01

    Two equation-of-state (EOS) models for multipy ionized matter are evaluated for the case of an aluminum plasma in the temperature range from about one eV to several hundred eV, spanning conditions of weak to strong ionization. Specifically, the simple analytical mode of Zel'dovich and Raizer and the more comprehensive model comprised by Rogers' plasma physics avtivity expansion code (ACTEX) are used to calculate the specific internal energy epsilon and average degree of ionization Z-bar*, as functons of temperature T and density rho. In the absence of experimental data, these results are compared against each other, covering almost five orders-of-magnitude variation in epsilon and the full range of Z-bar* We find generally good agreement between the two sets of results, especially for low densities and for temperatures near the upper end of the rage. Calculated values of epsilon(T) agree to within +- 30% over nearly the full range in T for densities below about 1 g/cm/sup 3/. Similarly, the two models predict values of Z-bar*(T) which track each other fairly well; above 20 eV the discrepancy is less than +- 20% fpr rho< or approx. =1 g/cm/sup 3/. Where the calculations disagree, we expect the ACTEX code to be more accurate than Zel'dovich and Raizer's model, by virtue of its more detailed physics content.

  2. Method Development for Binding Media Analysis in Painting Cross-Sections by Desorption Electrospray Ionization-Mass Spectrometry (DESI-MS).

    Science.gov (United States)

    Watts, Kristen; Lagalante, Anthony

    2018-06-06

    Art conservation science is in need of a relatively nondestructive way of rapidly identifying the binding media within a painting cross-section and isolating binding media to specific layers within the cross-section. Knowledge of the stratigraphy of cross-sections can be helpful for removing possible unoriginal paint layers on the artistic work. Desorption electrospray ionization-mass spectrometry (DESI-MS) was used in ambient mode to study cross-sections from mock-up layered paint samples and samples from a 17th century baroque painting. The DESI spray was raster scanned perpendicular to the cross-section layers to maximize lateral resolution then analyzed with a triple quadrupole mass analyzer in linear ion trap mode. From these scans, isobaric mass maps were created to map the locations of masses indicative of particular binding media onto the cross-sections. Line paint-outs of pigments in different binding media showed specific and unique ions to distinguish between the modern acrylic media and the lipid containing binding media. This included: OP (EO) 9 surfactant in positive ESI for acrylic (m/z 621), and oleic (m/z 281), stearic (m/z 283), and azelaic (m/z 187) acids in negative ESI for oil and egg tempera. DESI-MS maps of mock-up cross-sections of layered pigmented binding media showed correlation between these ions and the layers with a spatial resolution of 100 μm. DESI-MS is effective in monitoring binding media within an intact painting cross-section via mass spectrometric methods. This includes distinguishing between lipid-containing and modern binding materials present in a known mockup cross section matrix as well as identifying lipid binding media in a 17th century baroque era painting. This article is protected by copyright. All rights reserved.

  3. Analysis of Excitation and Ionization of Atoms and Molecules by Electron Impact

    CERN Document Server

    Chaudhry, Afzal

    2011-01-01

    Analysis of Excitation and Ionization of Atoms and Molecules by Electron Impact, by Afzal Chaudhry and Hans Kleinpoppen, describes in detail the measurements of the partial and total doubly differential cross sections for the multiple-ionization of rare gas atoms by electron impact. These measurements show, among other trends, the role of Auger transitions in the production of multiply ionized atoms in the region where the incident electron energy is sufficient to produce inner shell ionization. Other processes like Coster-Kronig transitions and shake off also contribute towards increasing the charge of the ions. As discussed in the book, an incident electron having energy of 6 keV, for example, in a collision with xenon atom can remove up to nine electrons! The measurements of doubly differential cross sections for the dissociative and non-dissociative ionization of hydrogen, sulfur dioxide and sulfur hexa fluoride molecular gases are also explored. The results of the measurements for the sulfur dioxide mole...

  4. Electron impact ionization of heavy ions: some surprises

    International Nuclear Information System (INIS)

    Younger, S.M.

    1986-01-01

    This paper reports the results of calculations of electron impact ionization cross sections for a variety of heavy ions using a distorted wave Born-exchange approximation. The target is described by a Hartree-Fock wavefunction. The scattering matrix element is represented by a triple partial wave expansion over incident, scattered, and ejected (originally bound) continuum states. These partial waves are computed in the potentials associated with the initial target (incident and scattered waves) and the residual ion (ejected waves). A Gauss integration was performed over the distribution of energy between the two final state continuum electrons. For ionization of closed d- and f-subshells, the ejected f-waves were computed in frozen-core term-dependent Hartree-Fock potentials, which include the strong repulsive contribution in singlet terms which arises from the interaction of an excited orbital with an almost closed shell. Ground state correlation was included in some calculations of ionization of d 10 subshells

  5. Partial Cancellation

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Partial Cancellation. Full Cancellation is desirable. But complexity requirements are enormous. 4000 tones, 100 Users billions of flops !!! Main Idea: Challenge: To determine which cross-talker to cancel on what “tone” for a given victim. Constraint: Total complexity is ...

  6. Development of a method of partial discharge detection in extra-high voltage cross-linked polyethylene insulated cable lines

    International Nuclear Information System (INIS)

    Katsuta, G.; Toya, A.; Muraoka, K.; Endoh, T.; Sekii, Y.; Ikeda, C.

    1992-01-01

    This paper reports that deterioration in the insulation performance of extra-high voltage XLPE cables is believed to be attributable to the deterioration caused by partial discharges. In the authors study, after using an XLPE cable to investigate the behavior of partial discharges under various adverse conditions, we succeeded in developing a highly sensitive new method of measuring partial discharge in XLPE cable lines. Partial discharges in a 275 kV XLPE cable live line has been measured using this newly developed method. As a result, a detection sensitivity of 1 pC has been achieved

  7. Absolute triple differential cross section for electron-impact ionization of helium at 40 eV

    International Nuclear Information System (INIS)

    Roeder, J.; Ehrhardt, H.; Bray, I.; Fursa, D.V.; McCarthy, I.E.

    1995-01-01

    A combined experimental and theoretical study of ionization of the ground state of helium by 40 eV incident electrons is presented. Absolute in-plane and out-of-plane measurements are provided for the case of 4 eV slow electron energy. These are found to be in good agreement with the convergent close-coupling (CCC) calculations. Three calculations are presented, in order to demonstrate convergence, which couple a total of 87, 99 and 103 states. These also simultaneously yield results for the equal energy sharing kinematics which are found to be in good agreement with the available relative coplanar symmetric measurement. 30 refs., 8 figs

  8. Effect of telescopic distal extension removable partial dentures on oral health related quality of life and maximum bite force: A preliminary cross over study.

    Science.gov (United States)

    Elsyad, Moustafa Abdou; Mostafa, Aisha Zakaria

    2018-01-01

    This cross over study aimed to evaluate the effect of telescopic distal extension removable partial dentures on oral health related quality of life and maximum bite force MATERIALS AND METHODS: Twenty patients with complete maxillary edentulism and partially edentulous mandibles with anterior teeth only remaining were selected for this cross over study. All patients received complete maxillary dentures and mandibular partial removable dental prosthesis (PRDP, control). After 3 months of adaptation, PRDP was replaced with conventional telescopic partial dentures (TPD) or telescopic partial dentures with cantilevered extensions (TCPD) in a quasi-random method. Oral health related quality of life (OHRQoL) was measured using OHIP-14 questionnaire and Maximum bite force (MBF) was measured using a bite force transducer. Measurements were performed 3 months after using each of the following prostheses; PRDP, TPD, and TCPD. TCPD showed the OHIP-14 lowest scores (i.e., the highest patient satisfaction with their OHRQoL), followed by TPD, and PRDP showed the highest OHIP-14 scores (i.e., the lowest patient satisfaction with OHRQoL). TCPD showed the highest MBF (70.7 ± 3.71), followed by TPD (57.4 ± 3.43) and the lowest MBF (40.2 ± 2.20) was noted with PRDP. WITHIN The Limitations of This Study, Mandibular Telescopic Distal Extension Removable Partial Dentures with Cantilevered Extensions Were Associated with Improved Oral Health Related Quality of Life and Maximum Bite Force Compared to Telescopic or Conventional PRDP. Telescopic distal extension removable prostheses is an esthetic restoration in partially edentulous patients with free end saddle. This article describes the addition of cantilevered extensions of this prosthesis. The results showed that telescopic distal extension removable prostheses with cantilevered extensions were associated with improved oral health related quality of life and maximum bite force compared to telescopic or conventional RPDs

  9. Attenuation and cross-attenuation in taste aversion learning in the rat: Studies with ionizing radiation, lithium chloride and ethanol

    International Nuclear Information System (INIS)

    Rabin, B.M.; Hunt, W.A.; Lee, J.

    1988-01-01

    The preexposure paradigm was utilized to evaluate the similarity of ionizing radiation, lithium chloride and ethanol as unconditioned stimuli for the acquisition of a conditioned taste aversion. Three unpaired preexposures to lithium chloride (3.0 mEq/kg, IP) blocked the acquisition of a taste aversion when a novel sucrose solution was paired with either the injection of the same dose of lithium chloride or exposure to ionizing radiation (100 rad). Similar pretreatment with radiation blocked the acquisition of a radiation-induced aversion, but had no effect on taste aversions produced by lithium chloride (3.0 or 1.5 mEq/kg). Preexposure to ethanol (4 g/kg, PO) disrupted the acquisition of an ethanol-induced taste aversion, but not radiation- or lithium chloride-induced aversions. In contrast, preexposure to either radiation or lithium chloride attenuated an ethanol-induced taste aversion in intact rats, but not in rats with lesions of the area postrema. The results are discussed in terms of relationships between these three unconditioned stimuli and in terms of implications of these results for understanding the nature of the proximal unconditioned stimulus in taste aversion learning

  10. Continuous emission, lowering of the ionization potential and total excitation cross-sections of an atmospheric thermal plasma

    NARCIS (Netherlands)

    Rosado, R.J.; Schram, D.C.; Leclair, J.

    1979-01-01

    The authors present a Partial LTE (PLTE) model in which the ground state is overpopulated with respect to the other excited states. The relative overpopulation of the ground state as a function of the electron temperature, T/sub e/, is fairly sensitive to small variations in both the transition

  11. Generation of L sub-shell photo-ionization cross-sections for elements 18Z92 at energies .320-115.606 keV (A computer program 'LSPICS')

    International Nuclear Information System (INIS)

    Sharma, Ajay; Mittal, Raj

    2005-01-01

    L sub-shell photo-ionization cross-sections, σ Li , for elements 18Z92 at energies .320-115.606 keV have been generated from an empirical relation fitted to Scofield's L sub-shell photo-ionization cross-section values. The excitation energy E for an element is constrained by the condition that only L and higher shell vacancies are produced in the elements. The closeness of generated and existing values of Scofield's L sub-shell data recommends the use of generated values in the fields of atomic and molecular physics and for trace elemental analysis. For this purpose computer software 'LSPICS' has been developed. On personal computer LSPICS generates L sub-shell photo-ionization cross-section values in barns just by entering the atomic number of element and excitation photon energy in keV

  12. Cross sections for double K-shell ionization in slow heavy ion-atom collisions, ch. 4

    International Nuclear Information System (INIS)

    Hoogkamer, T.P.; Woerlee, P.H.; Saris, F.W.

    1977-01-01

    Cross sections for Ksub(αα) X-ray production have been measured in collisions of 200 keV N + → NH 3 , N 2 , H 2 O; O + → NH 3 , H 2 O and 200, 400, 600 keV Ne 2+ → Ne. Fluorescence yields for Ksub(αα) two-electron one-photon transitions have been estimated for N and O, whereas for Ne, theoretical values for the fluorescence yield are available. We have used these to obtain double K-shell ionizzation cross sections which are compared to calculated cross section based on the theory for rotational coupling in the transient quasimolecular state

  13. Charge transfer and ionization involving argon ions and neutral hydrogen

    International Nuclear Information System (INIS)

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

    2006-01-01

    We present classical trajectory Monte Carlo (CTMC) calculations of total and partial cross sections for capture and ionization in Ar 18+ , Ar 17+ , Ar 16+ +H(1s) collisions in the 30-300 keV amu -1 impact energy range. We specially focus on capture into high-lying states of the projectile, which are of paramount importance for diagnostics of fusion plasmas involving Ar q+ seeding. (letter to the editor)

  14. Single electron ionization and electron capture cross sections for (C{sup 6+}, H{sub 2}O) interaction within the Classical Trajectory Monte Carlo (CTMC) approach

    Energy Technology Data Exchange (ETDEWEB)

    Tran, H.N., E-mail: tranngochoang@tdt.edu.vn [Division of Nuclear Physics, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Dao, D.D. [Division of Nuclear Physics, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Incerti, S. [Division of Nuclear Physics, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Université de Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); Bernal, M.A. [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, SP (Brazil); Karamitros, M. [CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Université de Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); Nhan Hao, T.V. [Center of Research and Development, Duy Tan University, K7/25 Quang Trung, Danang (Viet Nam); Center for Theoretical and Computational Physics, College of Education, Hue University, 34 Le Loi Street, Hue City (Viet Nam); Dang, T.M. [VNUHCM-University of Science (Viet Nam); Francis, Z. [Saint Joseph University, Beyrouth (Lebanon)

    2016-01-01

    In this work, we present a derivation of cross sections for single ionization and electron capture processes within the Classical Trajectory Monte Carlo (CTMC) approach. Specifically, we have used a potential stemming from an ab initio calculation in Green et al.’s framework to describe the dynamics of the water molecule system. Proposing a modified version of the Classical Over-Barrier (COB) potential, we have found that a cut-off of roughly 28 a.u. on the initial distance of the projectile produced a reasonable accuracy. A global agreement has been obtained in our calculations compared to experimental and other theoretical results for C{sup 6+} ion energies ranging from 10 keV/u to 10 MeV/u.

  15. Absolute triple differential cross section for electron-impact ionization of helium at 50 eV. Letter to the Editor

    International Nuclear Information System (INIS)

    Roeder, J.; Ehrhardt, H.; Bray, I.; Fursa, D.V.; McCarthy, I.E.

    1995-01-01

    A combined experimental and theoretical study of 50 eV electron-impact ionization of helium is presented. The absolute coplanar triple differential cross sections (TDCS) are measured for 4 eV and 10 eV slow electrons for fixed scattering angles; -20 deg, -25 deg, -30 deg and -35 deg of the fast electron. The convergent close-coupling (CCC) theory is used to calculate these and is found to be in good quantitative agreement with experiment for the 4 eV case, but lower than the measurement for the 10 eV case. The shape of the CCC theory shows good agreement with previous relative coplanar symmetric TDCS measurements. 11 refs., 4 figs

  16. 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

  17. Increased ionization rate in laser enrichment

    International Nuclear Information System (INIS)

    Janes, G.S.; Pike, G.T.

    1977-01-01

    A system employing multiple, upper excitation levels in a technique for isotopically selective ionization to improve the ionization efficiency is described. Laser radiation is employed to excite particles with isotopic selectivity. Excitation is produced to a plurality of excited states below the ionization level with the result of increasing the number of available excited particles for ionization and thereby increasing the ionization cross section for improved system efficiency

  18. Ionizing and non-ionizing radiations

    International Nuclear Information System (INIS)

    1994-01-01

    The monograph is a small manual to get a knowledge of ionizing and non-ionizing radiations. The main chapters are: - Electromagnetic radiations - Ionizing and non-ionizing radiations - Non-ionizing electromagnetic radiations - Ionizing electromagnetic radiation - Other ionizing radiations - Ionizing radiation effects - The Nuclear Safety Conseil

  19. Method of determining the partial cross sections in a heavy liquid. Application to the production of strange particles by high energy π"-

    International Nuclear Information System (INIS)

    Lloret, Antonio

    1964-01-01

    This research thesis reports the study if the measurement of cross sections on proton, and more particularly the development of a method of determination of cross sections which takes problems raised by a heavy liquid into account. This method is applied with sufficiently high energies for the Fermi momentum to have no influence on cross sections. The author first presents the general method of determination of partial cross sections in a heavy liquid: case of a hydrogen chamber, ideal case of a heavy liquid chamber without possibility of secondary interactions nor evaporations, search for a formula removing secondary interactions, correction due to the fact that the number of neutrons is not equal to the number of protons in the mixture nuclei, application to cross sections of production of high energy strange particles, calculation of the number of produced high energy particles. The experiment is then presented with its chamber, its measurement and calculation techniques. The author then reports and discusses cross section calculations and compares results with those of previous experiments. The last part addresses the study of secondary interactions in nuclei

  20. Universal empirical fit to L-shell X-ray production cross sections in ionization by protons

    Science.gov (United States)

    Lapicki, G.; Miranda, J.

    2018-01-01

    A compilation published in 2014, with a recent 2017 update, contains 5730 experimental total L-shell X-ray production cross sections (XRPCS). The database covers an energy range from 10 keV to 1 GeV, and targets from 18Ar to 95Am. With only two adjustable parameters, universal fit to these data normalized to XRPCS calculated at proton velocity v1 equal to the electron velocity in the L-shell v2L, is obtained in terms of a single ratio of v1/v2L. This fit reproduces 97% of the compiled XRPCS to within a factor of 2.

  1. 'Saddle-point' ionization

    International Nuclear Information System (INIS)

    Gay, T.J.; Hale, E.B.; Irby, V.D.; Olson, R.E.; Missouri Univ., Rolla; Berry, H.G.

    1988-01-01

    We have studied the ionization of rare gases by protons at intermediate energies, i.e., energies at which the velocities of the proton and the target-gas valence electrons are comparable. A significant channel for electron production in the forward direction is shown to be 'saddle-point' ionization, in which electrons are stranded on or near the saddle-point of electric potential between the receding projectile and the ionized target. Such electrons yield characteristic energy spectra, and contribute significantly to forward-electron-production cross sections. Classical trajectory Monte Carlo calculations are found to provide qualitative agreement with our measurements and the earlier measurements of Rudd and coworkers, and reproduce, in detail, the features of the general ionization spectra. (orig.)

  2. Ionizing radiation

    International Nuclear Information System (INIS)

    Kruger, J.

    1989-01-01

    Ionizing radiation results in biological damage that differs from other hazardous substances and is highly dangerous to man. Ionizing radiation cannot be perceived by man's sense organs and the biological damage cannot be detected immediately afterwards (except in very high doses). Every human being is exposed to low doses of radiation. The structure of the atom; sources of ionizing radiation; radiation units; biological effects; norms for radiation protection; and the national control in South Africa are discussed. 1 fig., 5 refs

  3. Electron ionization and the Compton effect in double ionization of helium

    International Nuclear Information System (INIS)

    Samson, J.

    1994-01-01

    The author discusses ionization phenomena in helium, both photoionization and electron ionization. In particular he compares double ionization cross sections with total cross sections, as a function of electron energy, and photon energy. Data is discussed over the energy range up to 10 keV

  4. Measurements of Total and Partial Charge-changing Cross Sections for 200-400 MeV/nucleon 12C in Water and Polycarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Toshito, T.; /CREST, Japan Sci. Tech. Corp. /KEK, Tsukuba; Kodama, K.; /Aichi U. of Education; Sihver, L.; /Chalmers U. Tech.; Yusa, K.; /Gunma U., Maebashi; Ozaki, M.; /JAXA, Sagamihara; Amako, K.; Kameoka, S.; Murakami, K.; Sasaki, T.; /KEK, Tsukuba; Aoki, S.; /Kobe U.; Ban, T.; Fukuda, T.; Komatsu, M.; Kubota, H.; Naganawa, N.; Nakamura, T.; Nakano, T.; Natsume, M.; Niwa, K.; Takahashi, S.; Yoshida, J.; /Nagoya U. /Naruto U. of Education /NIRS, Chiba /SLAC /Toho U.

    2011-11-10

    We have studied charged nuclear fragments produced by 200 - 400 MeV/nucleon carbon ions, interacting with water and polycarbonate, using a newly developed emulsion detector. Total and partial charge-changing cross sections for the production of B, Be, and Li fragments were measured and compared with both previously published measurements, and model predictions. This study is of importance for validating and improving carbon ion therapy treatment planning systems, and for estimating the radiological risks for personnel on space missions, since carbon is a significant component of the Galactic Cosmic Rays.

  5. Ionizing radiations

    International Nuclear Information System (INIS)

    Anon.

    1999-01-01

    This is an update about the radiological monitoring in base nuclear installations. A departmental order of the 23. march 1999 (J.O.28. april, p.6309) determines the enabling rules by the Office of Protection against Ionizing Radiations of person having at one's disposal the results with names of individual exposure of workers put through ionizing radiations. (N.C.)

  6. Cellular determinants of the inverse cross sensitivity of mouse lymphoma L5178Y cell lines to ionizing radiation and hydrogen peroxide

    International Nuclear Information System (INIS)

    Kruszewski, M.

    1999-01-01

    The pair of L5178Y sublines (LY-R and LY-S) is exceptional among mammalian cell lines because of their unique inverse cross-sensitivity to ionizing radiation and hydrogen peroxide. The high sensitivity of LY-S cells to ionizing radiation is reasonably explained by the impairment of DNA double strand breaks rejoining. Although the enzymatic defect of LY-S cells is not yet identified, the more pronounced effect of DNA-dependent protein kinase (DNA-PK) inhibitor (OK-1035) on DNA damage repair after 8 Gy x-irradiation in LY-R cells than in LY-S cells, suggests that LY-S cells may be defective in DNA-PK activity or in the other enzymatic activities downstream from DNA-PK. An additional feature is a higher protection of DNA against ionizing radiation by nuclear proteins in LY-R cells. These data support the concept that nuclear matrix organization may contribute to the cellular susceptibility to DNA damaging agents. Ionizing radiation-sensitive LY-S cells suffer also more DNA base damage than ionizing radiation-resistant LY-R cells. However, the repair rates of the γ-ray-induced DNA base damage in LY sublines are related neither to the initial amounts of the damaged bases nor to the lethal or mutagenic effects of ionizing radiation. In contrast, hydrogen peroxide (H 2 O 2 ) sensitive LY-R cells suffer more DNA base damage after H 2 O 2 treatment. This may be due to the lower activity of catalase and/or the lower level of glutathione and other monobromobimane-reactive thiols in LY-R cells than in LY-S cells. However, the main cause of LY-R cells' sensitivity to H 2 O 2 seems to be a higher iron ion content in these cells as compared to LY-S cells. A higher content of iron ions and a higher iron:copper ratio is found in isolated nuclei of LY-R cells than in those of LY-S cells. This is further confirmed by a higher ''labile iron'' pool in LY-R cells than in LY-S cells. Further evidence of different ions content in LY cells and its influence on nuclear matrix organization

  7. Measurement of total and partial photon proton cross sections at 180 GeV center of mass energy

    International Nuclear Information System (INIS)

    Derrick, M.; Krakauer, D.; Magill, S.

    1994-03-01

    Photon proton cross sections for elastic light vector meson production, σ el γp , inelastic diffractive production, σ d γp , non-diffractive procution, σ nd γp , as well as the total cross section, σ γp tot , have been measured at an average γp center of mass energy of 180 GeV with the ZEUS detector at HERA. The resulting values are σ el γp =18±7 μb, σ d γp =33±8 μb, σ nd γp =91±11 μb, and σ γp tot =143±17 μb, where the errors include statistical and systematic errors added in quadrature. (orig.)

  8. Electron collision cross section sets of TMS and TEOS vapours

    Science.gov (United States)

    Kawaguchi, S.; Takahashi, K.; Satoh, K.; Itoh, H.

    2017-05-01

    Reliable and detailed sets of electron collision cross sections for tetramethylsilane [TMS, Si(CH3)4] and tetraethoxysilane [TEOS, Si(OC2H5)4] vapours are proposed. The cross section sets of TMS and TEOS vapours include 16 and 20 kinds of partial ionization cross sections, respectively. Electron transport coefficients, such as electron drift velocity, ionization coefficient, and longitudinal diffusion coefficient, in those vapours are calculated by Monte Carlo simulations using the proposed cross section sets, and the validity of the sets is confirmed by comparing the calculated values of those transport coefficients with measured data. Furthermore, the calculated values of the ionization coefficient in TEOS/O2 mixtures are compared with measured data to confirm the validity of the proposed cross section set.

  9. Ionizing Radiation Processing Technology

    International Nuclear Information System (INIS)

    Rida Tajau; Kamarudin Hashim; Jamaliah Sharif; Ratnam, C.T.; Keong, C.C.

    2017-01-01

    This book completely brief on the basic concept and theory of ionizing radiation in polymers material processing. Besides of that the basic concept of polymerization addition, cross-linking and radiation degradation also highlighted in this informative book. All of the information is from scientific writing based on comprehensive scientific research in polymerization industry which using the radiation ionizing. It is very useful to other researcher whose study in Nuclear Sciencea and Science of Chemical and Material to use this book as a guideline for them in future scientific esearch.

  10. Microscale Solubility Measurements of Matrix-Assisted Laser Desorption-Ionization (MALDI) Matrices Using Attenuated Total Reflection (ATR) Fourier Transform Infrared Spectroscopy (FT-IR) Coupled with Partial Least Squares (PLS) Analysis.

    Science.gov (United States)

    Gorre, Elsa; Owens, Kevin G

    2016-11-01

    In this work an attenuated total reflection Fourier transform infrared (FT-IR) absorption based method is used to measure the solubility of two matrix-assisted laser desorption-ionization (MALDI) matrices in a few pure solvents and mixtures of acetonitrile and water using low microliter amounts of solution. Results from a method that averages the values obtained from multiple calibration curves created by manual peak picking are compared to those predicted using a partial least squares (PLS) chemometrics approach. The PLS method provided solubility values that were in good agreement with the manual method with significantly greater ease of analysis. As a test, the solubility of adipic acid in acetone was measured using the two methods of analysis, and the values are in good agreement with solubility values reported in literature. The solubilities of the MALDI matrices α-cyano-4-hydroxy cinnamic acid (CHCA) and sinapinic acid (SA) were measured in a series of mixtures made from acetonitrile (ACN) and water; surprisingly, the results show a highly nonlinear trend. While both CHCA and SA show solubility values of less than 10 mg/mL in the pure solvents, the solubility value for SA increases to 56.3 mg/mL in a 75:25 v/v ACN:water mixture. This can have a significant effect on the matrix-to-analyte ratios in the MALDI experiment when sample protocols call for preparation of a saturated solution of the matrix in the chosen solvent system. © The Author(s) 2016.

  11. Ionization chambers

    International Nuclear Information System (INIS)

    Boag, J.W.

    1987-01-01

    Although a variety of solid-state and chemical methods for measuring radiation dose have been developed in recent decades and calorimetry can now provide an absolute standard of reference, ionization dosimetry retains its position as the most widely used, most convenient, and, in most situations, most accurate method of measuring either exposure or absorbed dose. The ionization chamber itself is the central element in this system of dosimetry. In this chapter the principles governing the construction and operation of ionization chambers of various types are examined. Since the ionization chambers now in general use are nearly all of commercial manufacture, the emphasis is on operating characteristics and interpretation of measurements rather than on details of construction, although some knowledge of the latter is often required when applying necessary corrections to the measured quantities. Examples are given of the construction of typical chambers designed for particular purposes, and the methods of calibrating them are discussed

  12. Calcium - ionized

    Science.gov (United States)

    ... diuretics Thrombocytosis (high platelet count) Tumors Vitamin A excess Vitamin D excess Lower-than-normal levels may be due to: Hypoparathyroidism Malabsorption Osteomalacia Pancreatitis Renal failure Rickets Vitamin D deficiency Alternative Names Free calcium; Ionized calcium ...

  13. Ionization detector

    International Nuclear Information System (INIS)

    Solomon, E.E.

    1980-01-01

    A safe and reliable apparatus for detecting products of combustion and aerosols in the atmosphere was developed which uses a beta source. It is easy to adjust for optimum performance. The ionization detector comprises a double chamber; one of the chambers is the basic sensing chamber. The sensing chamber is ported to both the secondary chambers to account for slow ambient changes in the atmosphere outside of the chamber. The voltages from the ionization chamber are adjusted with electrodes in each chamber. The ionization chamber contains baffles to direct the air to be sensed as well as an electrostatic screen. A unique electronic circuit provides an inexpensive and reliable means for detecting the signal change which occurs in the ionization chamber. The decision level of the alarm circuit can be adjusted to allow for any desired sensitivity. (D.N.)

  14. Collisional ionization

    International Nuclear Information System (INIS)

    Arnaud, M.

    1985-07-01

    In low density, thin plasmas (such as stellar coronae, interstellar medium, intracluster medium) the ionization process is governed by collision between electrons and ions in their ground state. In view of the recent improvements we thought an updating of ionization rates was really needed. The work is based on both experimental data and theoretical works and give separate estimates for the direct and autoionization rates

  15. Ionization chamber

    International Nuclear Information System (INIS)

    Jilbert, P.H.

    1975-01-01

    The invention concerns ionization chambers with particular reference to air-equivalent ionization chambers. In order to ensure that similar chambers have similar sensitivities and responses the surface of the chamber bounding the active volume carries a conducting material, which may be a colloidal graphite, arranged in the form of lines so that the area of the conducting material occupies only a small proportion of the area of said surface. (U.S.)

  16. Indirect contributions to electron-impact ionization of Li+ (1 s 2 s S31 ) ions: Role of intermediate double-K -vacancy states

    Science.gov (United States)

    Müller, A.; Borovik, A.; Huber, K.; Schippers, S.; Fursa, D. V.; Bray, I.

    2018-02-01

    Fine details of the cross section for electron-impact ionization of metastable two-electron Li+(1 s 2 s S31) ions are scrutinized by both experiment and theory. Beyond direct knockoff ionization, indirect ionization mechanisms proceeding via formation of intermediate double-K-vacancy (hollow) states either in a Li+ ion or in a neutral lithium atom and subsequent emission of one or two electrons, respectively, can contribute to the net production of Li2 + ions. The partial cross sections for such contributions are less than 4% of the total single-ionization cross section. The characteristic steps, resonances, and interference phenomena in the indirect ionization contribution are measured with an experimental energy spread of less than 0.9 eV and with a statistical relative uncertainty of the order of 1.7%, requiring a level of statistical uncertainty in the total single-ionization cross section of better than 0.05%. The measurements are accompanied by convergent-close-coupling calculations performed on a fine energy grid. Theory and experiment are in remarkable agreement concerning the fine details of the ionization cross section. Comparison with previous R-matrix results is less favorable.

  17. Intranasal P particle vaccine provided partial cross-variant protection against human GII.4 norovirus diarrhea in gnotobiotic pigs.

    Science.gov (United States)

    Kocher, Jacob; Bui, Tammy; Giri-Rachman, Ernawati; Wen, Ke; Li, Guohua; Yang, Xingdong; Liu, Fangning; Tan, Ming; Xia, Ming; Zhong, Weiming; Jiang, Xi; Yuan, Lijuan

    2014-09-01

    Noroviruses (NoVs) are the leading cause of nonbacterial acute gastroenteritis worldwide in people of all ages. The P particle is a novel vaccine candidate derived from the protruding (P) domain of the NoV VP1 capsid protein. This study utilized the neonatal gnotobiotic pig model to evaluate the protective efficacies of primary infection, P particles, and virus-like particles (VLPs) against NoV infection and disease and the T cell responses to these treatments. Pigs either were vaccinated intranasally with GII.4/1997 NoV (VA387)-derived P particles or VLPs or were inoculated orally with a GII.4/2006b NoV variant. At postinoculation day (PID) 28, pigs either were euthanized or were challenged with the GII.4/2006b variant and monitored for diarrhea and virus shedding for 7 days. The T cell responses in intestinal and systemic lymphoid tissues were examined. Primary NoV infection provided 83% homologous protection against diarrhea and 49% homologous protection against virus shedding, while the P particle and VLP vaccines provided cross-variant protection (47% and 60%, respectively) against diarrhea. The protection rates against diarrhea are significantly inversely correlated with T cell expansion in the duodenum and are positively correlated with T cell expansion in the ileum and spleen. The P particle vaccine primed for stronger immune responses than VLPs, including significantly higher numbers of activated CD4+ T cells in all tissues, gamma interferon-producing (IFN-γ+) CD8+ T cells in the duodenum, regulatory T cells (Tregs) in the blood, and transforming growth factor β (TGF-β)-producing CD4+ CD25- FoxP3+ Tregs in the spleen postchallenge, indicating that P particles are more immunogenic than VLPs at the same dose. In conclusion, the P particle vaccine is a promising vaccine candidate worthy of further development. The norovirus (NoV) P particle is a vaccine candidate derived from the protruding (P) domain of the NoV VP1 capsid protein. P particles can be

  18. Spin-selected velocity dependence of the associative ionization cross section in Na(3p)+Na(3p) collisions over the collision energy range from 2.4 to 290 meV

    International Nuclear Information System (INIS)

    Wang, M.; Keller, J.; Boulmer, J.; Weiner, J.

    1987-01-01

    We report new results on the direct measurement of the associative ionization (AI) cross section in collisions between velocity-selected and spin-oriented Na(3p) atoms. Improvements in the Doppler-shift velocity-selection technique permit measurement over an energy range spanning more than two orders of magnitude from subthermal to suprathermal regions. Spin orientations, parallel and antiparallel, enable determination of the excitation function (velocity dependence of the AI cross section) for the separate singlet and triplet manifolds of Na 2 states contributing to the AI process

  19. Propagation of sound and thermal waves in an ionizing-recombining hydrogen plasma: Revision of results

    International Nuclear Information System (INIS)

    Di Sigalotti, Leonardo G.; Sira, Eloy; Tremola, Ciro

    2002-01-01

    The propagation of acoustic and thermal waves in a heat conducting, hydrogen plasma, in which photoionization and photorecombination [H + +e - H+hν(χ)] processes are progressing, is re-examined here using linear analysis. The resulting dispersion equation is solved analytically and the results are compared with previous solutions for the same plasma model. In particular, it is found that wave propagation in a slightly and highly ionized hydrogen plasma is affected by crossing between acoustic and thermal modes. At temperatures where the plasma is partially ionized, waves of all frequencies propagate without the occurrence of mode crossing. These results disagree with those reported in previous work, thereby leading to a different physical interpretation of the propagation of small linear disturbances in a conducting, ionizing-recombining, hydrogen plasma

  20. Sampling procedures using optical-data and partial wave cross sections in a Monte Carlo code for simulating kilovolt electron and positron transport in solids

    International Nuclear Information System (INIS)

    Fernandez-Varea, J.M.; Salvat, F.; Liljequist, D.

    1994-09-01

    The details of a Monte Carlo code for computing the penetration and energy loss of electrons and positrons in solids are described. The code, intended for electrons and positrons with energies from ∼ 100 eV to ∼ 100 keV, is based on the simulation of individual elastic and inelastic collisions. Elastic collisions are simulated using differential cross sections computed by the relativistic partial wave method applied to a muffin-tin Dirac-Hartree-Fock-Slater potential. Inelastic collisions are simulated by means of a model based on optical and photoelectric data, which are extended to the non-zero momentum transfer region by means of somewhat different algorithms for valence electron excitations and inner-shell excitations. This report focuses on the description of detailed formulae and sampling methods. 10 refs, 3 figs, 8 tabs

  1. Ionization in matrix-assisted laser desorption/ionization: singly charged molecular ions are the lucky survivors.

    Science.gov (United States)

    Karas, M; Glückmann, M; Schäfer, J

    2000-01-01

    A new model for the ionization processes in UV matrix-assisted laser desorption/ionization (MALDI) which accounts for the major phenomena observed is presented and discussed. The model retains elements of earlier approaches, such as photoionization and photochemical reactions, but it redefines these in the light of new working questions, most importantly why only singly charged ions are detected. Based on experimental evidence, the formation of singly and multiply charged clusters by a deficiency/excess of ions and also by photoionization and subsequent photochemical processes is pointed out to be the major ionization processes, which typically occur in parallel. The generation of electrons and their partial loss into the surrounding vacuum and solid, on the one hand, results in a positively charged ion-neutral plume facilitating a high overall ionization yield. On the other hand, these electrons, and also the large excess of protonated matrix ions in the negative ion mode, induce effective ion reneutralization in the plume. These neutralization processes are most effective for the highly charged cluster ions initially formed. Their fragmentation behaviour is evidenced in fast metastable fragmentation characteristics and agrees well with an electron capture dissociation mechanism and the enthalpy transfer upon neutralization forms the rationale for the prominent fragmentation and intense chemical noise accompanying successful MALDI. Within the course of the paper, cross-correlations with other desorption/ionization techniques and with earlier discussions on their mechanisms are drawn. Copyright 2000 John Wiley & Sons, Ltd.

  2. Velocity dependence of the cross sections for Penning, rearrangement, and total ionization of H2 and D2 molecules by He (23S) and He (21S) metastable atoms

    International Nuclear Information System (INIS)

    Fort, J.; Bolzinger, T.; Corno, D.; Ebding, T.; Pesnelle, A.

    1978-01-01

    The velocity dependence of both the Penning and rearrangement ionization cross sections sigma/sub PI/ and sigma/sub RI/ for H 2 /sup ts+/ and HeH + ion production, as well as total ionization cross section sigma/sub TI/, resulting from the collisions of He (2 1 S) and He (2 3 S) with H 2 is measured over the relative-velocity range 2400--5300 m/sec (0.04--0.20 eV energy range) in a crossed-beam experiment by a time-of-flight technique. Characteristic cross-section ratios sigma/sub RI//sigma/sub TI/ and the relative magnitude of the cross sections sigma/sub RI/, sigma/sub PI/, and sigma/sub TI/ are reported. Comparison with some recent theoretical calculations is made; we observe a fair agreement in the triplet case except for sigma/sub RI/, but a strong difference in the singlet case

  3. McGISH identification and phenotypic description of leaf rust and yellow rust resistant partial amphiploids originating from a wheat × Thinopyrum synthetic hybrid cross.

    Science.gov (United States)

    Kruppa, Klaudia; Türkösi, Edina; Mayer, Marianna; Tóth, Viola; Vida, Gyula; Szakács, Éva; Molnár-Láng, Márta

    2016-11-01

    A Thinopyrum intermedium × Thinopyrum ponticum synthetic hybrid wheatgrass is an excellent source of leaf and stem rust resistance produced by N.V.Tsitsin. Wheat line Mv9kr1 was crossed with this hybrid (Agropyron glael) in Hungary in order to transfer its advantageous agronomic traits into wheat. As the wheat parent was susceptible to leaf rust, the transfer of resistance was easily recognizable in the progenies. Three different partial amphiploid lines with leaf rust resistance were selected from the wheat/Thinopyrum hybrid derivatives by multicolour genomic in situ hybridization. Chromosome counting on the partial amphiploids revealed 58 chromosomes (18 wheatgrass) in line 194, 56 (14 wheatgrass) in line 195 and 54 (12 wheatgrass) in line 196. The wheat chromosomes present in these lines were identified and the wheatgrass chromosomes were characterized by fluorescence in situ hybridization using the repetitive DNA probes Afa-family, pSc119.2 and pTa71. The 3D wheat chromosome was missing from the lines. Molecular marker analysis showed the presence of the Lr24 leaf rust resistance gene in lines 195 and 196. The morphological traits were evaluated in the field during two consecutive seasons in two different locations.

  4. Single and multiple ionization of sulfur atoms by electron impact

    International Nuclear Information System (INIS)

    Ziegler, D.L.

    1982-01-01

    Laboratory measurements of the cross sections for single, double, triple, and quadruple ionization of sulfur atoms by electron impact are presented for collision energies from threshold to 500 eV. The cross sections for single ionization of sulfur are measured relative to those of several elements whose absolute cross sections for single ionization are known. Cross sections for each multiple ionization process are then measured relative to those for single ionization. The configuration and operation of the apparatus for these measurements are described. The possible effects of excited sulfur reactants are examined, and the reported cross sections are felt to be characteristic of ground state sulfur atoms

  5. Experimental investigation of the triple differential cross section for electron impact ionization of N{sub 2} and CO{sub 2} molecules at intermediate impact energy and large ion recoil momentum

    Energy Technology Data Exchange (ETDEWEB)

    Lahmam-Bennani, A; Staicu Casagrande, E M; Naja, A, E-mail: azzedine.bennani@u-psud.f [Universite Paris-Sud 11, Laboratoire des Collisions Atomiques et Moleculaires (LCAM), Bat. 351, 91405 Orsay Cedex (France)

    2009-12-14

    The (e,2e) triple differential cross sections (TDCS) are measured for the ionization of nitrogen and carbon dioxide molecules in a coplanar asymmetric geometry for a wide range of ejected electron energies and at an incident energy about 500-700 eV. This kinematics corresponds to a large momentum imparted to the ion, and is meant to enhance the recoil scattering. The experimental binary and recoil angular distributions of the TDCS are characterized both by a shift towards larger angles with respect to the momentum transfer direction and by a large intensity in the recoil region, in particular for the ionization of the 'inner' N{sub 2}(2{sigma}{sub g}) molecular orbital. The data are compared with the results of calculations using the first Born approximation-two centre continuum (FBA-TCC) theoretical model for treating differential electron impact ionization. The experimentally observed shifts and recoil intensity enhancement are not predicted by the model calculations, which rather yield a TDCS symmetrically distributed around the momentum transfer direction, and completely fail in describing the recoil distribution. It is hoped that these new results will stimulate the development of more refined theories for correctly modelling single ionization of molecules.

  6. Microwave ionization of hydrogen atoms below the classical chaos border

    Energy Technology Data Exchange (ETDEWEB)

    Bluemel, R; Smilansky, U

    1987-01-01

    We present and discuss theoretical predictions for the occurrence of radiation induced ionization of hydrogen atoms in fields which are well below the classical ionization threshold. Strong ionization occurs due to enhanced population of a band of high n states which ionize easily. This enhancement happens only at rather narrowly defined field values, and is explained in terms of avoided crossings of Floquet levels.

  7. Ionizing radiations

    International Nuclear Information System (INIS)

    Newton, W.

    1984-01-01

    The purpose of this article is to simplify some of the relevant points of legislation, biological effects and protection for the benefit of the occupational health nurse not familiar with the nuclear industries. The subject is dealt with under the following headings; Understanding atoms. What is meant by ionizing radiation. Types of ionizing radiation. Effects of radiation: long and short term somatic effects, genetic effects. Control of radiation: occupational exposure, women of reproductive age, medical aspects, principles of control. The occupational health nurse's role. Emergency arrangements: national arrangements for incidents involving radiation, action to be taken by the nurse. Decontamination procedures: external and internal contamination. (U.K.)

  8. III. Penning ionization, associative ionization and chemi-ionization processes

    International Nuclear Information System (INIS)

    Cermak, V.

    1975-01-01

    Physical mechanisms of three important ionization processes in a cold plasma and the methods of their experimental study are discussed. An apparatus for the investigation of the Penning ionization using ionization processes of long lived metastable rare gas atoms is described. Methods of determining interaction energies and ionization rates from the measured energy spectra of the originating electrons are described and illustrated by several examples. Typical associative ionization processes are listed and the ionization rates are compared with those of the Penning ionization. Interactions with short-lived excited particles and the transfer of excitation without ionization are discussed. (J.U.)

  9. Ionization effects in electronic inner-shells of ionized atoms

    International Nuclear Information System (INIS)

    Shchornak, G.

    1983-01-01

    A review of the atomic physics of ionization atoms has been presented. Interaction and structure effects in atomic shells, correlated to the occurrence of vacancies in several subshells of the atom have been considered. The methods of calculations of atomic states and wave functions have been reviewed. The energy shift of characteristic X-rays is discussed as a function of the ionization stage of the atom. The influence of inner and outer-shell vacancies on the energy of the X-rays is shown in detail. The influence of chemical effects on the parameters of X-rays is also taken into account. Further on, the change of transition probabilities in radiative and non-radiative transitions by changing stage of ionization is discussed; and among them the leading part of Auger and Coster-Kronig transitions by the arearrangement of the atomic states is shown. The influence of non-radiative electronic transitions on ionization cross-sections for multiple ionization is discussed. Using these results, ionization cross-sections for direct and indirect processes for several ionization stages are given

  10. Ionizing radiation

    International Nuclear Information System (INIS)

    Dennis, J.A.

    1982-01-01

    The subject is discussed under the headings: characteristics of ionizing radiations; biological effects; comparison of radiation and other industrial risks; principles of protection; cost-benefit analysis; dose limits; the control and monitoring of radiation; reference levels; emergency reference levels. (U.K.)

  11. Ionizing radiation

    Science.gov (United States)

    Tobias, C. A.; Grigoryev, Y. G.

    1975-01-01

    The biological effects of ionizing radiation encountered in space are considered. Biological experiments conducted in space and some experiences of astronauts during space flight are described. The effects of various levels of radiation exposure and the determination of permissible dosages are discussed.

  12. TECHNIQUE OF EXTRACORPOREAL PARTIAL NEPHRECTOMY IN TERMS OF PHARMACO-COLD ISCHEMIA WITHOUT CROSSING THE URETER WITH RENAL VESSELS ORTHOTOPIC REPLANTATION IN PATIENTS WITH RENAL CELL CARCINOMA

    Directory of Open Access Journals (Sweden)

    Alexander Gritskevitch

    2015-01-01

    Full Text Available Background. The most difficult is to determine medical tactics in patients with renal cell carcinoma (RCC with intraparenchimal and central localization in the single, the only functioning kidney, as well as with a combination of tumor and other illnesses in contralateral kidney. Partial nephrectomy leading to renal replacement therapy results in life-threatening complications and poor prognosis. The priority is to develop organ-preserving treatment: from minimally invasive endoscopic surgery to ex vivo kidney resection. Aim: to develop a technique of extracorporeal partial nephrectomy in terms of pharmaco-cold ischemia without crossing the ureter with renal vessels orthotopic replantation in patients with RCC. Materials and methods. The study included 37 patients with pT1a-T3vN0M0-1G1-3 RCC with intraparenchymal and central tumor location. The average age of the patients was 55.32 ± 13.1 years. The ratio of men and women - 2.7:1. Bilateral renal tumors were observed in 3 (8.1% patients, and the RCC of the single functioning kidney in 6 (16.2% patients. One patient (2.7% was diagnosed RCC of a single kidney with intraluminal invasion (cava-renal form. Results. The mean operation time was 413.97 ± 89.14 minutes. The mean warm ischemia time – 8.39 ± 4.75 minutes. Cold ischemia lasted from 70 to 240 minutes, on the average 151.41 ± 41.29 min. The amount of blood loss made up 729.03 ± 481.4 ml. Perioperative complications were detected in 3 (8.1% patients. In two cases after starting the renal blood flow the kidney was found to be nonviable and had to be removed. And in one case the recurrent prosthetic thrombosis of the renal artery resulted in a renal scarring. Postoperative complications were observed in 18 (48.6% patients. According to Clavien-Dindo classification there were 8 low grade (I-II degree complications (44.4%, 8 other of III degree, and one IV degree complication, and there was one lethal case (V degree. Conclusion

  13. Proton induced K-shell ionization cross sections for a wide range of elements (4 ≤ Z ≤ 92 within ECPSSR theory and updated experimental data

    Directory of Open Access Journals (Sweden)

    B. Deghfel

    2014-10-01

    Full Text Available Within the individual treatment of the elements from beryllium (4Be to uranium (92U, the experimental databases are normalized to their corresponding values of the ECPSSR model to deduce the semi-empirical cross sections. These databases rely on the different compilations available in the literature and on the other data extracted from papers published from 1953 till 2010. In the present paper, a fourth order polynomial was used to fit very well the existing normalized database of K-shell ionization cross sections by proton. These procedures generate a new set of parameters for the sake of the quick calculation of the semi-empirical cross sections. A comparison is made between the deduced results and those obtained by using the ECPSSR model where a remarkable discrepancy is observed at low-proton velocity regime especially for the lightest elements.

  14. Ionization of anisothermal plasmas

    International Nuclear Information System (INIS)

    Dennery, F.M.

    1994-01-01

    During this last mid-century, only the temperature of electrons has been involved in the Saha's mass action law, whatever be the other ionic and neutral ones in any isothermal or anisothermal plasma. In order to set aside this underlying paradox in the case of argon ionization, it is necessary to improve this equation of partial equilibrium after having defined: - the basic Gibbs-Duhem's relations for such a polythermal mixture, - the inhomogeneous equilibrium issued from chemical reactions according to Le Chatelier's principle. (author). 3 refs

  15. Differential cross sections for non-sequential double ionization of He by 52 eV photons from the Free Electron Laser in Hamburg, FLASH

    International Nuclear Information System (INIS)

    Kurka, M; Rudenko, A; Jiang, Y H; Kuehnel, K U; Foucar, L; Feist, J; Pazourek, R; Nagele, S; Horner, D A; Rescigno, T N; McCurdy, C W; Schoeffler, M; Belkacem, A; Schulz, M; Herrwerth, O; Lezius, M; Kling, M F; Duesterer, S; Treusch, R; Schneider, B I

    2010-01-01

    Two-photon double ionization of He is studied at the Free Electron Laser in Hamburg (FLASH) by inspecting He 2+ momentum (P-vector(He 2+ )) distributions at 52 eV photon energy. We demonstrate that recoil ion momentum distributions can be used to infer information about highly correlated electron dynamics and find the first experimental evidence for 'virtual sequential ionization'. The experimental data are compared with the results of two calculations, both solving the time-dependent Schroedinger equation. We find good overall agreement between experiment and theory, with significant differences for cuts along the polarization direction that cannot be explained by the experimental resolution alone.

  16. Valence ionized states of iron pentacarbonyl and eta5-cyclopentadienyl cobalt dicarbonyl studied by symmetry-adapted cluster-configuration interaction calculation and collision-energy resolved Penning ionization electron spectroscopy.

    Science.gov (United States)

    Fukuda, Ryoichi; Ehara, Masahiro; Nakatsuji, Hiroshi; Kishimoto, Naoki; Ohno, Koichi

    2010-02-28

    Valence ionized states of iron pentacarbonyl Fe(CO)(5) and eta(5)-cyclopentadienyl cobalt dicarbonyl Co(eta(5)-C(5)H(5))(CO)(2) have been studied by ultraviolet photoelectron spectroscopy, two-dimensional Penning ionization electron spectroscopy (2D-PIES), and symmetry-adapted cluster-configuration interaction calculations. Theory provided reliable assignments for the complex ionization spectra of these molecules, which have metal-carbonyl bonds. Theoretical ionization energies agreed well with experimental observations and the calculated wave functions could explain the relative intensities of PIES spectra. The collision-energy dependence of partial ionization cross sections (CEDPICS) was obtained by 2D-PIES. To interpret these CEDPICS, the interaction potentials between the molecules and a Li atom were examined in several coordinates by calculations. The relation between the slope of the CEDPICS and the electronic structure of the ionized states, such as molecular symmetry and the spatial distribution of ionizing orbitals, was analyzed. In Fe(CO)(5), an attractive interaction was obtained for the equatorial CO, while the interaction for the axial CO direction was repulsive. For Co(eta(5)-C(5)H(5))(CO)(2), the interaction potential in the direction of both Co-C-O and Co-Cp ring was attractive. These anisotropic interactions and ionizing orbital distributions consistently explain the relative slopes of the CEDPICS.

  17. K-shell ionization by antiprotons

    International Nuclear Information System (INIS)

    Mehler, G.; Mueller, B.; Greiner, W.; Soff, G.

    1987-01-01

    We present first calculations for the impact parameter dependence of K-shell ionization rates in anti pCu and in anti pAg collisions at various projectile energies. We show that the effect of the attractive Coulomb potential on the Rutherford trajectory and the anti-binding effect caused by the negative charge of the antiproton result in a considerable increase of the ionization probability. Total ionization cross-sections for proton and antiproton projectiles are compared with each other and with experimental ionization cross-sections for protons. (orig.)

  18. Ionization chamber

    International Nuclear Information System (INIS)

    1977-01-01

    An improved ionization chamber type X-ray detector comprises a heavy gas at high pressure disposed between an anode and a cathode. An open grid structure is placed next to the anode and is maintained at a voltage intermediate between the cathode and anode potentials. The electric field which is produced by positive ions drifting towards the cathode is thus shielded from the anode. Current measuring circuits connected to the anode are, therefore, responsive only to electron current flow within the chamber and the recovery time of the chamber is shortened. The grid structure also serves to shield the anode from electrical currents which might otherwise be induced by mechanical vibrations in the ionization chamber structure

  19. Theoretical and experimental investigation of the triple-differential cross sections for electron-impact ionization of Kr(4p) and Xe(5p) at 1-keV impact energy

    International Nuclear Information System (INIS)

    Rasch, J.; Zitnik, M.; Avaldi, L.; Whelan, C.T.; Stefani, G.; Camilloni, R.; Allan, R.J.; Walters, H.R.

    1997-01-01

    The triple-differential cross sections for the ionization of Kr(4p) and Xe(5p) by a fast electron where the exiting electrons have energies of 20 eV and 1 keV have been measured and compared with distorted-wave Born calculations. Difficulties were encountered when trying to place the relative data on an absolute scale by extrapolation to the optical limit: an extensive study of this normalization process is presented and it is argued that it is not applicable to the heavier atoms considered here, but can be used effectively for helium targets. copyright 1997 The American Physical Society

  20. Single and double ionization of gallium by electron impact

    Indian Academy of Sciences (India)

    Electron impact single and double ionization cross sections of gallium have been calcu- ... The experimental data on single ionization have been compared with the empirical and ..... and multiplication sign curve (¢¢¢) represent present.

  1. Ionization of highly excited atoms by atomic particle impact

    International Nuclear Information System (INIS)

    Smirnov, B.M.

    1976-01-01

    The ionization of a highly excited atom by a collision with an atom or molecule is considered. The theory of these processes is presented and compared with experimental data. Cross sections and ionization potential are discussed. 23 refs

  2. Thinking dimensional: prevalence of DSM-5 early adolescent full syndrome, partial and subthreshold eating disorders in a cross-sectional survey in German schools.

    Science.gov (United States)

    Hammerle, Florian; Huss, Michael; Ernst, Verena; Bürger, Arne

    2016-05-05

    Investigating for the first time in Germany Diagnostic and Statistical Manual Fifth Edition (DSM-5) prevalences of adolescent full syndrome, Other Specified Feeding or Eating Disorder (OSFED), partial and subthreshold anorexia nervosa (AN), bulimia nervosa (BN) and binge eating disorder (BED). A national school-based cross-sectional survey with nine schools in Germany was undertaken that was aimed at students from grades 7 and 8. Of the 1775 students who were contacted to participate in the study, 1654 participated (participation rate: 93.2%). The sample consisted of 873 female and 781 male adolescents (mean age=13.4 years). Prevalence rates were established using direct symptom criteria with a structured inventory (SIAB-S) and an additional self-report questionnaire (Eating Disorder Inventory 2 (EDI-2)). Prevalences for full syndrome were 0.3% for AN, 0.4% for BN, 0.5% for BED and 3.6% for OSFED-atypical AN, 0% for BN (low frequency/limited duration), 0% for BED (low frequency/limited duration) and 1.9% for purging disorder (PD). Prevalences of partial syndrome were 10.9% for AN (7.1% established with cognitive symptoms only, excluding weight criteria), 0.2% for BN and 2.1% for BED, and of subthreshold syndrome were 0.8% for AN, 0.3% for BN and 0.2% for BED. Cases on EDI-2 scales were much more pronounced with 12.6-21.1% of the participants with significant sex differences. The findings were in accordance with corresponding international studies but were in contrast to other German studies showing much higher prevalence rates. The study provides, for the first time, estimates for DSM-5 prevalences of eating disorders in adolescents for Germany, and evidence in favour of using valid measures for improving prevalence estimates. DRKS00005050; Results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  3. Ionization photophysics and Rydberg spectroscopy of diacetylene

    KAUST Repository

    Schwell, Martin; Bé nilan, Yves; Fray, Nicolas; Gazeau, Marie Claire; Es-sebbar, Et-touhami; Gaie-Levrel, Franç ois; Champion, Norbert; Leach, Sydney Sydney

    2012-01-01

    Photoionization of diacetylene was studied using synchrotron radiation over the range 8-24 eV, with photoelectron-photoion coincidence (PEPICO) and threshold photoelectron-photoion coincidence (TPEPICO) techniques. Mass spectra, ion yields, total and partial ionization cross-sections were measured. The adiabatic ionization energy of diacetylene was determined as IE ad=(10.17±0.01) eV, and the appearance energy of the principal fragment ion C4H+ as AE=(16.15±0.03) eV. Calculated appearance energies of other fragment ions were used to infer aspects of dissociation pathways forming the weaker fragment ions C+ 4, C3H+, C+3 and C 4H+. Structured autoionization features observed in the PEPICO spectrum of diacetylene in the 11-13 eV region were assigned to vibrational components of three new Rydberg series, R1(nsσg, n=4-11), R2(ndσg, n=4-7) and R3(ndδg, n=4-6) converging to the A2Πu state of the cation, and to a new series R01(nsσg, n=3) converging to the B' 2Σ+u state of the cation. The autoionization mechanisms and their consistence with specific selection rules are discussed. © 2012 Taylor and Francis.

  4. Ionization photophysics and Rydberg spectroscopy of diacetylene

    KAUST Repository

    Schwell, Martin

    2012-11-01

    Photoionization of diacetylene was studied using synchrotron radiation over the range 8-24 eV, with photoelectron-photoion coincidence (PEPICO) and threshold photoelectron-photoion coincidence (TPEPICO) techniques. Mass spectra, ion yields, total and partial ionization cross-sections were measured. The adiabatic ionization energy of diacetylene was determined as IE ad=(10.17±0.01) eV, and the appearance energy of the principal fragment ion C4H+ as AE=(16.15±0.03) eV. Calculated appearance energies of other fragment ions were used to infer aspects of dissociation pathways forming the weaker fragment ions C+ 4, C3H+, C+3 and C 4H+. Structured autoionization features observed in the PEPICO spectrum of diacetylene in the 11-13 eV region were assigned to vibrational components of three new Rydberg series, R1(nsσg, n=4-11), R2(ndσg, n=4-7) and R3(ndδg, n=4-6) converging to the A2Πu state of the cation, and to a new series R01(nsσg, n=3) converging to the B\\' 2Σ+u state of the cation. The autoionization mechanisms and their consistence with specific selection rules are discussed. © 2012 Taylor and Francis.

  5. Application of Discharges in Vapor of Evaporated Metals for the Film Deposition from the Ionized Stream

    International Nuclear Information System (INIS)

    Kostin, E.G.

    2006-01-01

    results of researches of the discharge device for ionization of the vapor of solid materials are presented. Evaporation of a material was made by an electron gun with a deviation of a beam on 180 degree. Diode type discharge device for ionization was placed above a surface of evaporated metal and was in a longitudinal adjustable magnetic field. Discharge was carried out in crossed electric and magnetic fields. Partial ionization of the vapor was made by primary and secondary electrons of the gun in a vapor cloud above evaporated substance. Physical properties and structure of the films. The comparative analysis of the films properties, besieged in conditions of influence of bombardment by ions of evaporated metal were studied depending on energy and the contents of ions in a stream of particles on a substrate

  6. Calculations of total electron-impact ionization cross sections for Fluoroketone C5F10O and Fluoronitrile C4F7N using modified Deutsch-Märk formula

    Science.gov (United States)

    Xiong, Jiayu; Li, Xingwen; Wu, Jian; Guo, Xiaoxue; Zhao, Hu

    2017-11-01

    Both fluoroketone C5F10O and fluoronitrile C4F7N are promising substitute gases for SF6. The electron-impact ionization cross sections for these two gases are calculated using the Deutsch-Märk (DM) formula and its modified method. The necessary molecular geometry optimization and electron population were determined by ab initio calculation, which was performed with quantum chemistry code. The level of calculation, including the theoretical method and basis-set, are carefully determined. To eliminate the drawbacks of the DM formula, a modified DM formula is set in this paper. The modified DM formula, of which the weighting factors are changed, has a better agreement with the experimental data on both the peak and shape of the cross-section curves. The results calculated by DM formula and modified DM formula are given as references to fill in gaps in further research into C5F10O and C4F7N.

  7. Ionization detector

    International Nuclear Information System (INIS)

    Steele, D.S.

    1987-01-01

    An ionization detector having an array of detectors has, for example, grounding pads positioned in the spaces between some detectors (data detectors) and other detectors (reference detectors). The grounding pads are kept at zero electric potential, i.e. grounded. The grounding serves to drain away electrons and thereby prevent an unwanted accumulation of charge in the spaces, and cause the electric field lines to be more perpendicular to the detectors in regions near the grounding pads. Alternatively, no empty space is provided there being additional, grounded, detectors provided between the data and reference detectors. (author)

  8. Ionizing radiations

    International Nuclear Information System (INIS)

    2009-01-01

    After having recalled some fundamental notions and measurement units related to ionizing radiations, this document describes various aspects of natural and occupational exposures: exposure modes and sources, exposure levels, biological effects, health impacts. Then, it presents prevention principles aimed at, in an occupational context of use of radiation sources (nuclear industry excluded), reducing and managing these exposures: risk assessment, implementation of safety from the front end. Some practical cases illustrate the radiation protection approach. The legal and regulatory framework is presented: general notions, worker exposure, measures specific to some worker categories (pregnant and breast feeding women, young workers, temporary workers). A last part describes what is to be done in case of incident or accident (dissemination of radioactive substances from unsealed sources, anomaly occurring when using a generator or a sealed source, post-accident situation)

  9. Modeling ionization by helicon waves

    International Nuclear Information System (INIS)

    Degeling, A.W.; Boswell, R.W.

    1997-01-01

    The response of the electron distribution function in one dimension to a traveling wave electric field is modeled for parameters relevant to a low-pressure helicon wave plasma source, and the resulting change in the ionization rate calculated. This is done by calculating the trajectories of individual electrons in a given wave field and assuming no collisions to build up the distribution function as the distance from the antenna is increased. The ionization rate is calculated for argon by considering the ionization cross section and electron flux at a specified position and time relative to the left-hand boundary, where the distribution function is assumed to be Maxwellian and the wave travels to the right. The simulation shows pulses in the ionization rate that move away from the antenna at the phase velocity of the wave, demonstrating the effect of resonant electrons trapped in the wave close-quote s frame of reference. It is found that the ionization rate is highest when the phase velocity of the wave is between 2 and 3x10 6 m/s, where the electrons interacting strongly with the wave (i.e., electrons with velocities inside the wave close-quote s open-quotes trapping widthclose quotes) have initial energies just below the ionization threshold. Results from the model are compared with experimental data and show reasonable qualitative agreement. copyright 1997 American Institute of Physics

  10. Electron-impact ionization of atomic ions: Theoretical results

    Energy Technology Data Exchange (ETDEWEB)

    Loch, S D; Burgos, J M Munoz; Ballance, C P; Ludlow, J; Lee, T-G; Fogle, M; Pindzola, M S [Auburn University, Auburn, AL 36849 (United States); Griffin, D C [Rollins College, Winter Park, FL 32789 (United States); Yumak, A; Yavuz, I; Altun, Z, E-mail: loch@physics.auburn.ed [Marmara University, Istanbul (Turkey)

    2009-11-15

    A brief overview is given of theoretical results for electron-impact ionization of atoms and ions. A description is given of the main theoretical methods, along with the databases where the data are archived. It is shown that for light species, ground and metastable ionization cross sections are in reasonable agreement with experiment when non-perturbative data are used for the near neutrals and distorted wave data are used for ions greater than a few times ionized. Some discrepancies between theory and experiment still remain for systems with open d and open p subshells. The sensitivity of ionization rate coefficients to the near threshold part of the ionization cross section is shown. The role of excited states in effective ionization rate coefficients is demonstrated and recent excited state ionization cross section results for H, He, He{sup +}, B{sup 2+} and Ne are presented.

  11. K-shell x-ray production cross sections of selected elements Al to Ni for 4. 0 to 38. 0 MeV /sup 10/B ions. [Cross sections, 4. 0 to 38 MeV, binding energy, electron capture decay, PWBA, energy shifts, multiple ionization

    Energy Technology Data Exchange (ETDEWEB)

    Monigold, G.; McDaniel, F.D.; Duggan, J.L.; Mehta, R.; Rice, R.; Miller, P.D.

    1976-01-01

    K-Shell x-ray production cross sections for the target elements Sc, Ti, V, Mn, Fe, Co, and Ni were measured for incident /sup 10/B ions over the energy range 4.0 to 38.0 MeV. The cross section data were compared to the theoretical predictions of the binary encounter approximation (BEA); the plane wave born approximation (PWBA); and the PWBA modified to include corrections for increased binding energy (B), Coulomb deflection of the incident ion (C), orbital perturbation due to polarization (P), and relativistic effects (R). In addition, fluorescence yield variations (W/sub K/) and contributions to the cross sections from electron capture (EC) were included. It was found that the predictions of the fully modified PWBA with contributions from electron capture and fluorescence yield variations included provided the best fit to the experimental data over the entire energy range for each target element. The K..beta../K..cap alpha.. x-ray intensity ratios were compared to theoretical values that assume single hole ionization, and the x-ray energy shifts presented as a function of the energy of the incident ion. These two measurements provided confirmation of the occurrence of multiple ionization for /sup 10/B bombardment of target elements in the range 21 less than or equal to Z/sub 2/ less than or equal to 28.

  12. Ring magnetron ionizer

    International Nuclear Information System (INIS)

    Alessi, J.G.

    1986-01-01

    A ring magnetron D - charge exchange ionizer has been built and tested. An H - current of 500 μA was extracted with an estimated H 0 density in the ionizer of 10 12 cm -3 . This exceeds the performance of ionizers presently in use on polarized H - sources. The ionizer will soon be tested with a polarized atomic beam

  13. Comparison of growth on mannitol salt agar, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, VITEK® 2 with partial sequencing of 16S rRNA gene for identification of coagulase-negative staphylococci.

    Science.gov (United States)

    Ayeni, Funmilola A; Andersen, Camilla; Nørskov-Lauritsen, Niels

    2017-04-01

    Mannitol salt agar (MSA) is often used in resources' limited laboratories for identification of S. aureus however, coagulase-negative staphylococci (CoNS) grows and ferments mannitol on MSA. 171 strains of CoNS which have been previously misidentified as S. aureus due to growth on MSA were collected from different locations in Nigeria and two methods for identification of CoNS were compared i.e. ViTEK 2 and MALDI-TOF MS with partial 16S rRNA gene sequencing as gold standard. Partial tuf gene sequencing was used for contradicting identification. All 171 strains (13 species) grew on MSA and ferments mannitol. All tested strains of S. epidermidis, S. haemolyticus, S. nepalensis, S. pasteuri, S. sciuri,, S. warneri, S. xylosus, S. capitis were correctly identified by MALDI-TOF while variable identification were observed in S. saprophyticus and S. cohnii (90%, 81%). There was low identification of S. arlettae (14%) while all strains of S. kloosii and S. gallinarum were misidentified. There is absence of S. gallinarum in the MALDI-TOF database at the period of this study. All tested strains of S. epidermidis, S. gallinarum, S. haemolyticus, S. sciuri,, S. warneri, S. xylosus and S. capitis were correctly identified by ViTEK while variable identification were observed in S. saprophyticus, S. arlettae, S. cohnii, S. kloosii, (84%, 86%, 75%, 60%) and misidentification of S. nepalensis, S. pasteuri. Partial sequencing of 16S rRNA gene was used as gold standard for most strains except S. capitis and S. xylosus where the two species were misidentified by partial sequencing of 16S rRNA contrary to MALDI-TOF and ViTEK identification. Tuf gene sequencing was used for correct identification. Characteristic growth on MSA for CoNS is also identical to S. aureus growth on the media and therefore, MSA could not differentiate between S. aureus and CoNS. The percentage accuracy of ViTEK was better than MALDI-TOF in identification of CoNS. Although partial sequencing of

  14. Display of charged ionizing particles

    International Nuclear Information System (INIS)

    Cano S, D.; Ortiz A, M. D.; Amarillas S, L. E.; Vega C, H. R.

    2017-10-01

    The human being is exposed to sources of ionizing and non-ionizing radiation, both of natural or anthropogenic origin. None of these, except non-ionizing such as visible light and infrared radiation, can be detected by the sense of sight and touch respectively. The sun emits charged particles with speeds close to the light that interact with the atoms of the gases present in the atmosphere, producing nuclear reactions that in turn produce other particles that reach the surface of the Earth and reach the living beings. On Earth there are natural radioisotopes that, when they disintegrate, emit ionizing radiation that contributes to the dose we receive. A very old system that allows the visualization of the trajectories of the charged ionizing particles is the Fog Chamber that uses a saturated steam that when crossed by particles with mass and charge, as alpha and beta particles produce condensation centers along its path leaves a trace that can be seen. The objective of this work was to build a fog chamber using easily accessible materials. To measure the functioning of the fog chamber, cosmic rays were measured, as well as a source of natural metal uranium. The fog chamber allowed seeing the presence of traces in alcohol vapor that are produced in a random way. Introducing the uranium foil inside the fog chamber, traces of alpha particles whose energy varies from 4 to 5 MeV were observed. (Author)

  15. Laser-induced ionization of Na vapor

    International Nuclear Information System (INIS)

    Wu, R.C.Y.; Judge, D.L.; Roussel, F.; Carre, B.; Breger, P.; Spiess, G.

    1982-01-01

    The production of Na 2 + ions by off-resonant laser excitation in the 5800-6200A region mainly results from two-photon absorption by the Na 2 molecule to highly excited gerade states followed by (a) direct ionization by absorbing a third photon or (b) coupling to the molecular Na 2 D 1 PIμ Rydberg state which is subsequently ionized by absorbing a third photon. This mechanism, i.e., a two-photon resonance three photon ionization process, explains a recent experimental observation of Roussel et al. It is suggested that the very same mechanism is also responsible for a similar observation reported by Polak-Dingels et al in their work using two crossed Na beams. In the latter two studies the laser-induced associative ionization processes were reported to be responsible for producing the Na 2 + ion. From the ratio of molecular to atomic concentration in the crossed beam experiment of Polak-Dingels et al we estimate that the cross section for producing Na 2 + through laser-induced associative ionization is at least four orders of magnitude smaller than ionization through the two-photon resonance three photon ionization process in Na 2 molecules

  16. Multiple ionization and coupling effects in L-subshell ionization of heavy atoms by oxygen ions

    International Nuclear Information System (INIS)

    Pajek, M.; Banas, D.; Semaniak, J.; Braziewicz, J.; Majewska, U.; Chojnacki, S.; Czyzewski, T.; Fijal, I.; Jaskola, M.; Glombik, A.; Kretschmer, W.; Trautmann, D.; Lapicki, G.; Mukoyama, T.

    2003-01-01

    The multiple-ionization and coupling effects in L-shell ionization of atoms by heavy-ion impact have been studied by measuring the L x-ray production cross sections in solid targets of Au, Bi, Th, and U bombarded by oxygen ions in the energy range 6.4-70 MeV. The measured L x-ray spectra were analyzed using the recently proposed method accounting for the multiple-ionization effects, such as x-ray line shifting and broadening, which enables one to obtain the ionization probabilities for outer shells. The L-subshell ionization cross sections have been obtained from measured x-ray production cross sections for resolved Lα 1,2 , Lγ 1 , and Lγ 2,3 transitions using the L-shell fluorescence and Coster-Kronig yields being substantially modified by the multiple ionization in the M and N shells. In particular, the effect of closing of strong L 1 -L 3 M 4,5 Coster-Kronig transitions in multiple-ionized atoms was evidenced and discussed. The experimental ionization cross sections for the L 1 , L 2 , and L 3 subshells have been compared with the predictions of the semiclassical approximation (SCA) and the ECPSSR theory that includes the corrections for the binding-polarization effect within the perturbed stationary states approximation, the projecticle energy loss, and Coulomb deflection effects as well as the relativistic description of inner-shell electrons. These approaches were further modified to include the L-subshell couplings within the ''coupled-subshell model'' (CSM). Both approaches, when modified for the coupling effects, are in better agreement with the data. Particularly, the predictions of the SCA-CSM calculations reproduce the experimental L-subshell ionization cross section reasonably well. Remaining discrepancies are discussed qualitatively, in terms of further modifications of the L-shell decay rates caused by a change of electronic wave functions in multiple-ionized atoms

  17. Olefin cross metathesis based de novo synthesis of a partially protected L-amicetose and a fully protected L-cinerulose derivative

    Directory of Open Access Journals (Sweden)

    Bernd Schmidt

    2014-05-01

    Full Text Available Cross metathesis of a lactate derived allylic alcohol and acrolein is the entry point to a de novo synthesis of 4-benzoate protected L-amicetose and a cinerulose derivative protected at C5 and C1.

  18. Electron induced atomic inner-shell ionization

    International Nuclear Information System (INIS)

    Quarles, C.A.

    1974-01-01

    The current status of cross section measurements for atomic inner-shell ionization by electron bombardment is reviewed. Inner shell ionization studies using electrons as projectiles compliment the similar studies being done with heavy particles, and in addition can provide tests of the theory in those cases when relativistic effects and exchange effects are expected to be important. Both total cross sections and recently measured differential cross sections will be discussed and compared with existing theories where possible. Prospects for further experimental and theoretical work in this area of atomic physics using small electron accelerators will also be discussed

  19. Double-differential cross section for ionization of H2O molecules by 4-MeV/u C6 + and Si13 + ions

    Science.gov (United States)

    Bhattacharjee, Shamik; Biswas, S.; Monti, J. M.; Rivarola, R. D.; Tribedi, L. C.

    2017-11-01

    Double-differential cross section (DDCS) for electrons ejected in collisions of fast C6 + and Si13 + projectiles, with a H2O vapor target, were measured. The electrons were detected over an energy range of 1-600 eV and an angular range of 20∘-160∘. The obtained DDCS spectra, for both the ions, were compared with the CDW-EIS model. Occasional reference has been made to the DDCS data for the case of 3.75-MeV/u O8 + colliding on the same molecule for an overall comparison. A reasonable agreement with theoretical results was seen for the case of C6 + and O8 + projectiles. However, between C6 + and O8 + projectiles, the deviation from theory is larger for the case of the carbon projectile. Substantial deviation starts to show up for the case of the Si13 + projectile. By numerical integration of the DDCS data, the single-differential cross section (SDCS) and total cross section (TCS) were obtained and compared with theoretical models. The present TCS data along with the other available data for p , He , and C ions were plotted together. A clear and gradual deviation from the Bethe-Born predicted q2 scaling was observed, where q is the projectile charge state. From all the data we find TCS varies as qn where n = 1.7 ± 0.1. The provided data set will be valuable in order to help model the radiation damage in hadron therapy, particularly in the Bragg peak region.

  20. Partial processing

    International Nuclear Information System (INIS)

    1978-11-01

    This discussion paper considers the possibility of applying to the recycle of plutonium in thermal reactors a particular method of partial processing based on the PUREX process but named CIVEX to emphasise the differences. The CIVEX process is based primarily on the retention of short-lived fission products. The paper suggests: (1) the recycle of fission products with uranium and plutonium in thermal reactor fuel would be technically feasible; (2) it would, however, take ten years or more to develop the CIVEX process to the point where it could be launched on a commercial scale; (3) since the majority of spent fuel to be reprocessed this century will have been in storage for ten years or more, the recycling of short-lived fission products with the U-Pu would not provide an effective means of making refabrication fuel ''inaccessible'' because the radioactivity associated with the fission products would have decayed. There would therefore be no advantage in partial processing

  1. Ionization of atoms by bare ion projectiles

    International Nuclear Information System (INIS)

    Tribedi, L.C.

    1997-01-01

    The double differential cross sections (DDCS) for low energy electron emission can provide stringent tests to the theoretical models for ionization in ion-atom collision. The two-center effects and the post collision interactions play a major role in ionization by highly charged, high Z projectiles. We close-quote ll review the recent developments in this field and describe our efforts to study the energy and angular distributions of the low energy electrons emitted in ion-atom ionization. copyright 1997 American Institute of Physics

  2. Partial gigantism

    Directory of Open Access Journals (Sweden)

    М.М. Karimova

    2017-05-01

    Full Text Available A girl with partial gigantism (the increased I and II fingers of the left foot is being examined. This condition is a rare and unresolved problem, as the definite reason of its development is not determined. Wait-and-see strategy is recommended, as well as correcting operations after closing of growth zones, and forming of data pool for generalization and development of schemes of drug and radial therapeutic methods.

  3. Above-threshold ionization of atoms by resonant XUV laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, V D [Departamento de Fisica and IFIBA-CONICET, FCEyN, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina); Arbo, D G [Instituto de AstronomIa y Fisica del Espacio, FCEN-UBA CONICET, CC 67 Suc 28 Buenos Aires (Argentina); Macri, P A, E-mail: vladimir@df.uba.ar [Departamento de Fisica, FCEyN, Instituto de Investigaciones Fisicas de Mar del Plata (IFIMAR), Universidad Nacional de Mar del Plata-CONICET, Funes 3350, 7600 Mar del Plata (Argentina)

    2011-06-28

    Above-threshold ionization of atoms by XUV short laser pulses with frequencies close to the resonant 1s-2p transition is investigated. We present a theory based on a variational expression using trial wavefunctions for the final and the initial states. For the former we use a Coulomb-Volkov wavefunction, and for the latter a close-coupling solution of the time-dependent Schroedinger equation considering a few bound states. The close-coupling Coulomb-Volkov theory, fully accounting for the important 1s-2p transition, explains the photoelectron spectrum as well as the total ionization cross sections for the resonant case. We also compare the partial wave populations and angular distributions given by the theory with the numerical solutions of the time-dependent Schroedinger equation.

  4. Sensitivity of hot-cathode ionization vacuum gages in several gases

    Science.gov (United States)

    Holanda, R.

    1972-01-01

    Four hot-cathode ionization vacuum gages were calibrated in 12 gases. The relative sensitivities of these gages were compared to several gas properties. Ionization cross section was the physical property which correlated best with gage sensitivity. The effects of gage accelerating voltage and ionization-cross-section energy level were analyzed. Recommendations for predicting gage sensitivity according to gage type were made.

  5. Ionization of food products

    International Nuclear Information System (INIS)

    Vasseur, J.P.

    1991-01-01

    After general remarks on foods preservation, on international works and on ionization future prospects, main irradiation sources are described. Recalls on radioactivity, on radiation-matter interaction, on toxicology of ionized foods and on ionized foods detection are given. Ionization applications to various products are reviewed, especially in: - Poultry meat - Fishing products - Fresh fruits and vegetables - Dry fruits and vegetables - spices, tea, infusion - prepacked products... An evaluation of economics and sociocultural impacts is presented in connection with recent experiments [fr

  6. Foodstuffs preservation by ionization

    International Nuclear Information System (INIS)

    1991-12-01

    This document contains all the papers presented at the meeting on foodstuffs preservation by ionization. These papers deal especially with the food ionization process, its development and the view of the food industry on ionization. Refs and figs (F.M.)

  7. Electron-Impact Ionization and Dissociative Ionization of Biomolecules

    Science.gov (United States)

    Huo, Winifred M.; Chaban, Galina M.; Dateo, Christopher E.

    2006-01-01

    It is well recognized that secondary electrons play an important role in radiation damage to humans. Particularly important is the damage of DNA by electrons, potentially leading to mutagenesis. Molecular-level study of electron interaction with DNA provides information on the damage pathways and dominant mechanisms. Our study of electron-impact ionization of DNA fragments uses the improved binary-encounter dipole model and covers DNA bases, sugar phosphate backbone, and nucleotides. An additivity principle is observed. For example, the sum of the ionization cross sections of the separate deoxyribose and phosphate fragments is in close agreement with the C3(sup prime)- and C5 (sup prime)-deoxyribose-phospate cross sections, differing by less than 5%. Investigation of tandem double lesion initiated by electron-impact dissociative ionization of guanine, followed by proton reaction with the cytosine in the Watson-Crick pair, is currently being studied to see if tandem double lesion can be initiated by electron impact. Up to now only OH-induced tandem double lesion has been studied.

  8. Multiphoton ionization of atomic cesium

    International Nuclear Information System (INIS)

    Compton, R.N.; Klots, C.E.; Stockdale, J.A.D.; Cooper, C.D.

    1984-01-01

    We describe experimental studies of resonantly enhanced multi-photon ionization (MPI) of cesium atoms in the presence and absence of an external electric field. In the zero-field studies, photo-electron angular distributions for one- and two-photon resonantly enhanced MPI are compared with the theory of Tang and Lambropoulos. Deviations of experiment from theory are attributed to hyperfine coupling effects in the resonant intermediate state. The agreement between theory and experiment is excellent. In the absence of an external electric field, signal due to two-photon resonant three-photon ionization of cesium via np states is undetectable. Application of an electric field mixes nearby nd and ns levels, thereby inducing excitation and subsequent ionization. Signal due to two-photon excitation of ns levels in field-free experiments is weak due to their small photoionization cross section. An electric field mixes nearby np levels which again allows detectable photo-ionization signal. For both ns and np states the ''field induced'' MPI signal increases as the square of the electric field for a given principal quantum number and increases rapidly with n for a given field strength

  9. Multiphoton ionization of atomic cesium

    International Nuclear Information System (INIS)

    Compton, R.N.; Klots, C.E.; Stockdale, J.A.D.; Cooper, C.D.

    1984-01-01

    We describe experimental studies of resonantly enhanced multiphoton ionization (MPI) of cesium atoms in the presence and absence of an external electric field. In the zero-field studies, photoelectron angular distributions for one- and two-photon resonantly enhanced MPI are compared with the theory of Tang and Lambropoulos. Deviations of experiment from theory are attributed to hyperfine coupling effects in the resonant intermediate state. The agreement between theory and experiment is excellent. In the absence of an external electric field, signal due to two-photon resonant three-photon ionization of cesium via np states is undetectable. Application of an electric field mixes nearby nd and ns levels, thereby inducing excitation and subsequent ionization. Signal due to two-photon excitation of ns levels in field-free experiments is weak due to their small photoionization cross section. An electric field mixes nearby np levels which again allows detectable photoionization signal. For both ns and np states the field induced MPI signal increases as the square of the electric field for a given principal quantum number and increases rapidly with n for a given field strength. Finally, we note that the classical two-photon field-ionization threshold is lower for the case in which the laser polarization and the electric field are parallel than it is when they are perpendicular. 22 references, 11 figures

  10. Acceleration of electrons and supplementary ionization during parametrical plasma heating

    International Nuclear Information System (INIS)

    Grach, S.M.; Mityakov, N.A.; Trakhtengerts, V.Yu.; AN SSSR, Gor'kij. Inst. Prikladnoj Fiziki)

    1986-01-01

    Acceleration of electrons by plasma waves in partially ionized plasma is considered with provision for the effects of turbulent scattering and formation of secondary electrons, which are produced in the process of electron shock ionization. It is shown that the avalanche density growth of electrons accelerated up to 1-2 ionization potential (instability) takes place beginning from some critical density of plasma waves. Density of fast electrons is found out along with plasma wave energy density at the stage of instability saturation. Additional concentration of a background plasma, which manifests itself due to ionization, is evaluated

  11. Cellular determinants of the inverse cross sensitivity of mouse lymphoma L5178Y cell lines to ionizing radiation and hydrogen peroxide; Podloze odwrotnej krzyzowej opornosci komorek L5178Y na promieniowanie jonizujace i nadtlenek wodoru

    Energy Technology Data Exchange (ETDEWEB)

    Kruszewski, M [Dept. of Radiobiology and Health Protection, Inst. of Nuclear Chemistry and Technology, Warsaw (Poland)

    1999-07-01

    The pair of L5178Y sublines (LY-R and LY-S) is exceptional among mammalian cell lines because of their unique inverse cross-sensitivity to ionizing radiation and hydrogen peroxide. The high sensitivity of LY-S cells to ionizing radiation is reasonably explained by the impairment of DNA double strand breaks rejoining. Although the enzymatic defect of LY-S cells is not yet identified, the more pronounced effect of DNA-dependent protein kinase (DNA-PK) inhibitor (OK-1035) on DNA damage repair after 8 Gy x-irradiation in LY-R cells than in LY-S cells, suggests that LY-S cells may be defective in DNA-PK activity or in the other enzymatic activities downstream from DNA-PK. An additional feature is a higher protection of DNA against ionizing radiation by nuclear proteins in LY-R cells. These data support the concept that nuclear matrix organization may contribute to the cellular susceptibility to DNA damaging agents. Ionizing radiation-sensitive LY-S cells suffer also more DNA base damage than ionizing radiation-resistant LY-R cells. However, the repair rates of the {gamma}-ray-induced DNA base damage in LY sublines are related neither to the initial amounts of the damaged bases nor to the lethal or mutagenic effects of ionizing radiation. In contrast, hydrogen peroxide (H{sub 2}O{sub 2}) sensitive LY-R cells suffer more DNA base damage after H{sub 2}O{sub 2} treatment. This may be due to the lower activity of catalase and/or the lower level of glutathione and other monobromobimane-reactive thiols in LY-R cells than in LY-S cells. However, the main cause of LY-R cells' sensitivity to H{sub 2}O{sub 2} seems to be a higher iron ion content in these cells as compared to LY-S cells. A higher content of iron ions and a higher iron:copper ratio is found in isolated nuclei of LY-R cells than in those of LY-S cells. This is further confirmed by a higher ''labile iron'' pool in LY-R cells than in LY-S cells. Further evidence of different ions content in LY cells and its influence

  12. Absolute photoionization cross sections of two cyclic ketones: cyclopentanone and cyclohexanone.

    Science.gov (United States)

    Price, Chelsea; Fathi, Yasmin; Meloni, Giovanni

    2017-05-01

    Absolute photoionization cross sections for cyclopentanone and cyclohexanone, as well as partial ionization cross sections for the dissociative ionized fragments, are presented in this investigation. Experiments are performed via a multiplexed photoionization mass spectrometer utilizing vacuum ultraviolet (VUV) synchrotron radiation supplied by the Advanced Light Source of Lawrence Berkeley National Laboratory. These results allow the quantification of these species that is relevant to investigate the kinetics and combustion reactions of potential biofuels. The CBS-QB3 calculated values for the adiabatic ionization energies agree well with the experimental values, and the identification of possible dissociative fragments is discussed for both systems. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  13. Investigation on the absolute and relative photoionization cross sections of 3 potential propargylic fuels.

    Science.gov (United States)

    Winfough, Matthew; Meloni, Giovanni

    2017-12-01

    Absolute photoionization cross sections for 2 potential propargylic fuels (propargylamine and dipropargyl ether) along with the partial ionization cross sections for their dissociative fragments are measured and presented for the first time via synchrotron photoionization mass spectrometry. The experimental setup consists of a multiplexed orthogonal time-of-flight mass spectrometer and is located at the Advanced Light Source facility of the Lawrence Berkeley National Laboratory in Berkeley, California. Data for a third propargylic compound (propargyl alcohol) were taken; however, because of its low signal, due to its weakly bound cation, only the dissociative ionization fragment from the H-loss channel is observed and presented. Suggested pathways leading to formation of dissociative photoionization fragments along with CBS-QB3 calculated adiabatic ionization energies and appearance energies for the dissociative fragments are also presented. Copyright © 2017 John Wiley & Sons, Ltd.

  14. Absolute photoionization cross sections of furanic fuels: 2-ethylfuran, 2-acetylfuran and furfural.

    Science.gov (United States)

    Smith, Audrey R; Meloni, Giovanni

    2015-11-01

    Absolute photoionization cross sections of the molecules 2-ethylfuran, 2-acetylfuran and furfural, including partial ionization cross sections for the dissociative ionized fragments, are measured for the first time. These measurements are important because they allow fuel quantification via photoionization mass spectrometry and the development of quantitative kinetic modeling for the complex combustion of potential fuels. The experiments are carried out using synchrotron photoionization mass spectrometry with an orthogonal time-of-flight spectrometer used for mass analysis at the Advanced Light Source of Lawrence Berkeley National Laboratory. The CBS-QB3 calculations of adiabatic ionization energies and appearance energies agree well with the experimental results. Several bond dissociation energies are also derived and presented. Copyright © 2015 John Wiley & Sons, Ltd.

  15. Electron-impact single and double ionization of W

    International Nuclear Information System (INIS)

    Pindzola, M S; Loch, S D; Foster, A R

    2017-01-01

    Electron-impact single and double ionization cross sections for the W atom are calculated using a semi-relativistic distorted-wave method. The cross sections include contributions from single direct ionization, double direct ionization and excitation-autoionization. Branching ratio calculations are made to determine whether an excitation may contribute to single or double ionization. We check the accuracy of the semi-relativistic distorted-wave calculations for direct ionization of various subshells by comparison with fully-relativistic distorted-wave calculations. We also check the accuracy of the perturbative distorted-wave calculations for direct ionization of the outer most subshells by comparison with non-perturbative time-dependent close-coupling calculations. (paper)

  16. Inner shell ionization accompanying nuclear collisions

    International Nuclear Information System (INIS)

    Sujkowski, Z.

    1987-01-01

    Selected phenomena leading to inner shell ionization and being of relevance for nuclear physics are discussed. The selection emphasizes the K-shell ionization induced in head-on collisions by fast light and medium-heavy ions. Cross-sections are reviewed. Effects of multiple inner shell ionization on the K X-ray spectra are illustrated with recent results. Implications for nuclear experiments are noted. Use of atomic observables as clocks for proton induced nuclear reactions is reviewed. Prospects for H.I. reactions are discussed. Preliminary experimental results on the direct K-shell ionization accompanying H.I. fusion reactions are presented. The post-collisional K-shell ionization due to internal conversion of γ-rays is discussed as the dominating contribution to the ionization for residues of dissipative nuclear reactions with Z > 40. Systematics of the corresponding K X-ray multiplicities are presented for rotational nuclei. These multiplicity values can be used for determining cross-sections for e.g. incomplete fusion reactions. Examples of such applications are given. Also discussed is the use of target K X-rays for normalization purposes and of the post-collisional, residue K X-rays in the studies of high spin phenomena. 96 references, 35 figures, 3 tables

  17. A pepducin derived from the third intracellular loop of FPR2 is a partial agonist for direct activation of this receptor in neutrophils but a full agonist for cross-talk triggered reactivation of FPR2.

    Directory of Open Access Journals (Sweden)

    Michael Gabl

    Full Text Available We recently described a novel receptor cross-talk mechanism in neutrophils, unique in that the signals generated by the PAF receptor (PAFR and the ATP receptor (P2Y2R transfer formyl peptide receptor 1 (FPR1 from a desensitized (non-signaling state back to an actively signaling state (Forsman H et al., PLoS One, 8:e60169, 2013; Önnheim K, et al., Exp Cell Res, 323∶209, 2014. In addition to the G-protein coupled FPR1, neutrophils also express the closely related receptor FPR2. In this study we used an FPR2 specific pepducin, proposed to work as an allosteric modulator at the cytosolic signaling interface, to determine whether the cross-talk pathway is utilized also by FPR2. The pepducin used contains a fatty acid linked to a peptide sequence derived from the third intracellular loop of FPR2, and it activates as well as desensensitizes this receptor. We now show that neutrophils desensitized with the FPR2-specific pepducin display increased cellular responses to stimulation with PAF or ATP. The secondary PAF/ATP induced response was sensitive to FPR2-specific inhibitors, disclosing a receptor cross-talk mechanism underlying FPR2 reactivation. The pepducin induced an activity in naïve cells similar to that of a conventional FPR2 agonist, but with lower potency (partial efficacy, meaning that the pepducin is a partial agonist. The PAF- or ATP-induced reactivation was, however, much more pronounced when neutrophils had been desensitized to the pepducin as compared to cells desensitized to conventional agonists. The pepducin should thus in this respect be classified as a full agonist. In summary, we demonstrate that desensitized FPR2 can be transferred back to an actively signaling state by receptor cross-talk signals generated through PAFR and P2Y2R, and the difference in agonist potency with respect to pepducin-induced direct receptor activation and cross-talk reactivation of FPR2 puts the concept of functional selectivity in focus.

  18. Partial Cross Sections of Neutron-Induced Reactions on nCu at En = 6, 8, 10, 12, 14, and 16 MeV for 0νββ Background Studies

    Science.gov (United States)

    Gooden, M. E.; Fallin, B. A.; Finch, S. W.; Kelley, J. H.; Howell, C. R.; Rusev, G.; Tonchev, A. P.; Tornow, W.; Stanislav, V.

    2014-05-01

    Partial cross-section measurements of (n,n'γ) reactions on natCu were carried out at TUNL using monoenergetic neutrons at six energies of En = 6, 8, 10, 12, 14, 16 MeV. These studies were performed to provide accurate cross-section data on materials abundant in experimental setups involving HPGe detectors used to search for rare events, like the neutrino-less double-beta decay of 76Ge. Spallation and (α,n) neutrons are expected to cause the largest source of external background in the energy region of interest. At TUNL pulsed neutron beams were produced via the 2H(d,n)3He reaction and the deexcitation γ rays from the reaction natCu(n,xγ) were detected with clover HPGe detectors. Cross-section results for the strongest transtions in 63Cu and 65Cu will be reported, and will compared to model calculations and to data recently obtained at LANL with a white neutron beam.

  19. Partial cross sections for Rb- photodetachment in the region of the Rb(5p2Psub(1/2,3/2)) thresholds and their analysis by multichannel quantum defect theory

    International Nuclear Information System (INIS)

    Frey, P.; Lawen, M.; Breyer, F.; Klar, H.; Hotop, H.

    1982-01-01

    A crossed ion-laser beam apparatus has been used to measure accurate relative total and partial cross sections for photodetachment from Rb - ions with high photon energy resolution (0.1-0.6 cm -1 ) in the region of the Rb(5p 2 Psub(1/2,3/2)) thresholds (photon energy range 16.350-16.820 cm -1 ). Satisfactory fits to these data by multichannel quantum defect theory (MQDT) have been obtained, resulting in a reliable set of seven MQDT parameters. The electron angular distribution parameter for the Rb(5s) channel was found to be β(5s)=2, independent of photon energy, MQDT predicts a sharp, window-type variation of β(5s) around the minimum of the 5s-cross section below the Rb(5p 2 Psub(1/2)) threshold (where an accurate experimental measurement of β(5s) was not possible) and a similar behaviour of β(6s) in the case of Cs - photodetachment below the Cs(6p 2 Psub(1/2)) threshold. (orig.)

  20. Seasonal influenza split vaccines confer partial cross-protection against heterologous influenza virus in ferrets when combined with the CAF01 adjuvant

    DEFF Research Database (Denmark)

    Christensen, Dennis; Christensen, Jan P.; Korsholm, Karen S.

    2018-01-01

    Influenza epidemics occur annually, and estimated 5-10% of the adult population and 20-30% of children will become ill from influenza infection. Seasonal vaccines primarily work through the induction of neutralizing antibodies against the principal surface antigen hemagglutinin (HA). This important...... role of HA-specific antibodies explains why previous pandemics have emerged when new HAs have appeared in circulating human viruses. It has long been recognized that influenza virus-specific CD4(+) T cells are important in protection from infection through direct effector mechanisms or by providing...... help to B cells and CD8(+) T cells. However, the seasonal influenza vaccine is poor at inducing CD4(+) T-cell responses and needs to be combined with an adjuvant facilitating this response. In this study, we applied the ferret model to investigate the cross-protective efficacy of a heterologous...

  1. Multiple ionization of atoms by ion impact

    International Nuclear Information System (INIS)

    DuBois, R.D.

    1988-01-01

    In order to model the energy deposition of fast ions as they slow down in gaseous media, information about the ionization occurring in collisions between ions and target atoms/molecules is required. Our measurements of doubly differential electron emission cross sections provide detailed information about the ionization process but do not provide any information about the final states of the target. They also do not distinguish between the emission of one or more target electrons in a single collision. It is important to know the relative importance of multiple-, with respect to single-, target ionization in order to accurately model the energy deposition. To date, multiple ionization of He, Ne, Ar, Kr, and Xe targets has been studied. Primarily, H and He ions were used, although some data for heavier ions (C,N and O) have also been obtained

  2. Accurate Cross Sections for Microanalysis

    OpenAIRE

    Rez, Peter

    2002-01-01

    To calculate the intensity of x-ray emission in electron beam microanalysis requires a knowledge of the energy distribution of the electrons in the solid, the energy variation of the ionization cross section of the relevant subshell, the fraction of ionizations events producing x rays of interest and the absorption coefficient of the x rays on the path to the detector. The theoretical predictions and experimental data available for ionization cross sections are limited mainly to K shells of a...

  3. Ionizing radiation in environment

    International Nuclear Information System (INIS)

    Jandl, J.; Petr, I.

    1988-01-01

    The basic terms are explained such as the atom, radioactivity, nuclear reaction, interaction of ionizing radiation with matter, etc. The basic dosimetric variables and units and properties of radionuclides and ionizing radiation are given. Natural and artificial sources of ionizing radiation are discussed with regard to the environment and the propagation and migration of radionuclides is described in the environment to man. The impact is explained of ionizing radiation on the cell and the somatic and genetic effects of radiation on man are outlined. Attention is devoted to protection against ionizing radiation and to radiation limits, also to the detection, dosimetry and monitoring of ionizing radiation in the environment. (M.D.). 92 figs., 40 tabs. 74 refs

  4. Ionization of liquids

    International Nuclear Information System (INIS)

    Gregg, E.C.; Bakale, G.

    1976-01-01

    Application of pulsed-conductivity techniques to ionization phenomena in liquids has yielded new results on electron transport and electron reactions in nonpolar liquids which we have extrapolated to biological systems to develop a novel model of direct radiation damage to mammalian cells that involves the unsolvated electron as the key reactant. Among these new results are electron attachment rate constants of thirty-five substituted nitrobenzene compounds measured in nonpolar solvents which when combined with product anion lifetimes are correlated with cellular radiosensitization efficiencies. From this study we found that electron attachment rates are dependent upon the electron mobility in the solvents and upon the dipole moment of the electron-accepting nitrobenzene compounds. The model also drawn upon energy-dependent electron attachment rates which we have measured in cryogenic liquids, and we have measured in the same solvents associative detachment rate constants and electron momentum transfer cross sections. In addition to these studies of electronic processes in liquids, we have measured ion mobilities of lecithin and chlorophyll in nonpolar solvents and conclude that these solutes form inverse micelles under certain conditions. Formation of these micelles permits electron transport through the lipid micellar walls and electron attachment to electron-accepting polar solutes inside the lipid vesicles to be studied

  5. Ionizing radiation in hospitals

    International Nuclear Information System (INIS)

    Blok, K.; Ginkel, G. van; Leun, K. van der; Muller, H.; Oude Elferink, J.; Vesseur, A.

    1985-10-01

    This booklet dels with the risks of the use of ionizing radiation for people working in a hospital. It is subdivided in three parts. Part 1 treats the properties of ionizing radiation in general. In part 2 the various applications are discussed of ionizing radiation in hospitals. Part 3 indicates how a not completely safe situation may be improved. (H.W.). 14 figs.; 4 tabs

  6. Dosimetry of ionizing radiation

    International Nuclear Information System (INIS)

    Musilek, L.; Seda, J.; Trousil, J.

    1992-01-01

    The publication deals with a major field of ionizing radiation dosimetry, viz., integrating dosimetric methods, which are the basic means of operative dose determination. It is divided into the following sections: physical and chemical effects of ionizing radiation; integrating dosimetric methods for low radiation doses (film dosimetry, nuclear emulsions, thermoluminescence, radiophotoluminescence, solid-state track detectors, integrating ionization dosemeters); dosimetry of high ionizing radiation doses (chemical dosimetric methods, dosemeters based on the coloring effect, activation detectors); additional methods applicable to integrating dosimetry (exoelectron emission, electron spin resonance, lyoluminescence, etc.); and calibration techniques for dosimetric instrumentation. (Z.S.). 422 refs

  7. Management of corneal ectasia after LASIK with combined, same-day, topography-guided partial transepithelial PRK and collagen cross-linking: the athens protocol.

    Science.gov (United States)

    Kanellopoulos, Anastasios John; Binder, Perry S

    2011-05-01

    To evaluate a series of patients with corneal ectasia after LASIK that underwent the Athens Protocol: combined topography-guided photorefractive keratectomy (PRK) to reduce or eliminate induced myopia and astigmatism followed by sequential, same-day ultraviolet A (UVA) corneal collagen cross-linking (CXL). Thirty-two consecutive corneal ectasia cases underwent transepithelial PRK (WaveLight ALLEGRETTO) immediately followed by CXL (3 mW/cm(2)) for 30 minutes using 0.1% topical riboflavin sodium phosphate. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent, keratometry, central ultrasonic pachymetry, corneal tomography (Oculus Pentacam), and endothelial cell counts were analyzed. Mean follow-up was 27 months (range: 6 to 59 months). Twenty-seven of 32 eyes had an improvement in UDVA and CDVA of 20/45 or better (2.25 logMAR) at last follow-up. Four eyes showed some topographic improvement but no improvement in CDVA. One of the treated eyes required a subsequent penetrating keratoplasty. Corneal haze grade 2 was present in 2 eyes. Combined, same-day, topography-guided PRK and CXL appeared to offer tomographic stability, even after long-term follow-up. Only 2 of 32 eyes had corneal ectasia progression after the intervention. Seventeen of 32 eyes appeared to have improvement in UDVA and CDVA with follow-up >1.5 years. This technique may offer an alternative in the management of iatrogenic corneal ectasia. Copyright 2011, SLACK Incorporated.

  8. Determining partial differential cross sections for low-energy electron photodetachment involving conical intersections using the solution of a Lippmann-Schwinger equation constructed with standard electronic structure techniques.

    Science.gov (United States)

    Han, Seungsuk; Yarkony, David R

    2011-05-07

    A method for obtaining partial differential cross sections for low energy electron photodetachment in which the electronic states of the residual molecule are strongly coupled by conical intersections is reported. The method is based on the iterative solution to a Lippmann-Schwinger equation, using a zeroth order Hamiltonian consisting of the bound nonadiabatically coupled residual molecule and a free electron. The solution to the Lippmann-Schwinger equation involves only standard electronic structure techniques and a standard three-dimensional free particle Green's function quadrature for which fast techniques exist. The transition dipole moment for electron photodetachment, is a sum of matrix elements each involving one nonorthogonal orbital obtained from the solution to the Lippmann-Schwinger equation. An expression for the electron photodetachment transition dipole matrix element in terms of Dyson orbitals, which does not make the usual orthogonality assumptions, is derived.

  9. First measurement of the ratio of central-electron to forward-electron W partial cross sections in pp[over] collisions at (square root)s =1.96 TeV.

    Science.gov (United States)

    Abulencia, A; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carillo, S; Carlsmith, D; Carosi, R; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Cilijak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Almenar, C Cuenca; Cuevas, J; Culbertson, R; Cully, J C; DaRonco, S; Datta, M; D'Auria, S; Davies, T; Dagenhart, D; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'Orso, M; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Giovanni, G P Di; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Dörr, C; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraan, A C; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lu, R-S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moon, C S; Moore, R; Morello, M; Fernandez, P Movilla; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shalhout, S Z; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; Denis, R St; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuno, S; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vazquez, F; Velev, G; Vellidis, C; Veramendi, G; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vollrath, I; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, J; Wagner, W; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zhou, J; Zucchelli, S

    2007-06-22

    We present a measurement of sigma(pp[over] --> W) x B(W --> e nu) at (square root)s = 1.96 TeV, using electrons identified in the forward region (1.2 < |eta| < 2.8) of the CDF II detector, in 223 pb(-1) of data. We measure sigma x B = 2796 +/- 13(stat)(-90)(+95)(syst) +/- 162(lum) pb. Combining this result with a previous CDF measurement obtained using electrons in the central region (|eta| approximately < 1), we present the first measurement of the ratio of central-electron to forward-electron W partial cross sections R(exp) = 0.925 +/- 0.006(stat) +/- 0.032(syst), consistent with theoretical predictions using Coordinated Theoretical-Experimental Project on QCD (CTEQ) and Martin-Roberts-Stirling-Thorne (MRST) parton distribution functions.

  10. First Measurement of the Ratio of Central-Electron to Forward-Electron W Partial Cross Sections in p anti-p Collisions at s**(1/2) = 1.96 TeV

    Energy Technology Data Exchange (ETDEWEB)

    Abulencia, A.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; Annovi, A.; /Taiwan, Inst. Phys.

    2007-02-01

    We present a measurement of {sigma}(p{bar p} {yields} W) x {Beta}(W {yields} e{nu}) at {radical}s = 1.96 TeV, using electrons identified in the forward region (1.2 < |{eta}| < 2.8) of the CDF II detector. The data correspond to an integrated luminosity of 223 pb{sup -1}. We measure {sigma} x {Beta} = 2796 {+-} 13(stat){sub -90}{sup +95}(syst){+-}162 (lum) pb. Combining this result with a previous CDF measurement obtained using electrons in the central region (|{eta}| {approx}< 1), we present the first measurement of the ratio of central-electron to forward-electron W partial cross sections R{sub exp} = 0.925 {+-} 0.006(stat){+-}0.032(syst), consistent with theoretical predictions using CTEQ and MRST parton distribution functions.

  11. Progress in zirconium resonance ionization spectroscopy

    International Nuclear Information System (INIS)

    Page, R.H.; Dropinski, S.C.; Worden, E.F.; Stockdale, J.A.D.

    1993-01-01

    The authors have examined the stepwise-resonant three-photon-ionization spectrum of neutral zirconium atoms using three separately-tunable pulsed visible dye lasers. The ground-level (first-step) transitions were chosen on the basis of demonstrated 91 Zr selectivity. Lifetimes of even-parity levels around 36,000 cm -1 , measured with the delayed-photoionization technique, range from 10 to 100 nsec. Direct ionization cross sections appear to be less than 10 -17 cm 2 ; newly-detected autoionizing levels give peak ionization cross sections (inferred from saturation fluences) up to 10 -15 cm 2 . Portions of Rydberg series converging to the 315 and 763 cm -1 levels of Zr + were identified. Clumps of autoionizing levels are thought to be due to Rydberg-valence mixing

  12. Antiproton impact ionization of atomic hydrogen and helium

    Energy Technology Data Exchange (ETDEWEB)

    McGovern, M; Walters, H R J [Department of Applied Mathematics and Theoretical Physics, Queen' s University, Belfast BT7 INN (United Kingdom); Assafrao, D; Mohallem, J R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, P.O Box 702, 30123-970 Belo Horizonte, MG (Brazil); Whelan, Colm T, E-mail: mmcgovern06@qub.ac.u [Department of Physics, Old Dominion University, Norfolk, VA 23529-0116 (United States)

    2009-11-01

    We shall present results for antiproton ionization of H and He ranging from fully differential cross sections to total ionization. The calculations have been made in a coupled pseudostate impact parameter approximation. It will be shown that the interaction between the antiproton and the target nucleus is very important at low energies.

  13. Partial-wave analysis of K/sup +/p elastic scattering. [Cross sections, polarization, dispersion relations, analytic smoothing threshold structure, 0. 78 to 2. 53 GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Cutkosky, R E; Hicks, H R; Sandusky, J; Shih, C C [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA); Kelly, R L [California Univ., Livermore (USA). Lawrence Livermore Lab.; Miller, R C; Yokosawa, A [Argonne National Lab., Ill. (USA)

    1976-01-05

    K/sup +/p cross-section and polarization data have been analyzed in the momentum range 0.78-2.53 GeV/c. Single energy fits were made using an ACE parametrization which had no cutoff in J, was analytic and has Regge-asymptotic behaviour in the cut cos theta plane, and contained explicit contributions from P, rho, A2, ..lambda.., ..sigma.., and low-mass di-pion exchange. Direct channel analyticity constraints were imposed by a partial wave dispersion relation interpolation procedure, fitting expansions in regulated-norm optimal bases to each partial wave which entered as a search parameter in the single energy fits. Output from these two programs was then used for a simultaneous fit by a linearized least squares program which provided input for another iterative fitting cycle. No strong evidence for the existence of exotic resonances was found. The method of analytic smoothing, in comparison with 'shortest path' methods, is found to allow more significant threshold structure to appear in the amplitudes.

  14. Partial characterization of the cross-reacting determinant, a carbohydrate epitope shared by decay accelerating factor and the variant surface glycoprotein of the African Trypanosoma brucei.

    Science.gov (United States)

    Shak, S; Davitz, M A; Wolinsky, M L; Nussenzweig, V; Turner, M J; Gurnett, A

    1988-03-15

    The variant surface glycoprotein (VSG) of the African trypanosome is anchored in the cell membrane by a complex glycan attached to phosphatidylinositol. The carboxyl terminal portion of VSG contains a cryptic carbohydrate epitope, the cross-reacting determinant (CRD), that is revealed only after removal of the diacylglycerol by phosphatidylinositol-specific phospholipase C (PIPLC) or VSG lipase. Recently, we have shown that after hydrolysis by PIPLC, decay-accelerating factor (DAF)--a mammalian phosphatidylinositol-anchored protein--also contains the CRD epitope. Using a two site immunoradiometric assay in which the capturing antibody is a monoclonal antibody to DAF and the revealing antibody is anti-CRD, we now show that sugar phosphates significantly inhibited the binding of anti-CRD antibody to DAF released by PIPLC. DL-myo-inositol 1,2-cyclic phosphate was the most potent inhibitor of binding (IC50 less than 10(-8) M). Other sugar phosphates, such as alpha-D-glucose-1-phosphate, which also possess adjacent hydroxyl and phosphate moieties in cis also inhibited binding at low concentrations (IC50 = 10(-5) to 10(-4) M). In contrast, sugar phosphates which do not possess adjacent hydroxyl and phosphate moieties in cis and simple sugars weakly inhibited binding (IC50 greater than 10(-3) M). These results suggest that myo-inositol 1,2-cyclic phosphate contributes significantly to the epitope recognized by the anti-CRD antibody and is consistent with analysis of the carboxyl terminus of VSG, which also suggested the presence of the cyclic inositol phosphate. In light of the recent findings that human serum contains a glycan-phosphatidyl-inositol-specific phospholipase D, which converts DAF from a hydrophobic to a hydrophilic form lacking the CRD, the observation that the phosphate is crucial for expression of the epitope may be relevant in understanding the origin of CRD-negative DAF in urine and plasma.

  15. Electron impact ionization of Ar8+

    International Nuclear Information System (INIS)

    Defrance, P.; Rachafi, S.; Jureta, J.; Meyer, F.; Chantrenne, S.

    1986-01-01

    Absolute electron impact ionization cross-sections have been measured for the Neon-like Ar 8+ in the energy range from below the threshold for the metastable state to 2500 eV. No contribution of metastable states is observed. The results are well reproduced by the Distorted Wave Born Approximation. 12 refs., 1 fig

  16. Identification of super-infected Aedes triseriatus mosquitoes collected as eggs from the field and partial characterization of the infecting La Crosse viruses

    Directory of Open Access Journals (Sweden)

    Beaty Barry J

    2010-04-01

    Full Text Available Abstract Background La Crosse virus (LACV is a pathogenic arbovirus that is transovarially transmitted by Aedes triseriatus mosquitoes and overwinters in diapausing eggs. However, previous models predicted transovarial transmission (TOT to be insufficient to maintain LACV in nature. Results To investigate this issue, we reared mosquitoes from field-collected eggs and assayed adults individually for LACV antigen, viral RNA by RT-PCR, and infectious virus. The mosquitoes had three distinct infection phenotypes: 1 super infected (SI+ mosquitoes contained infectious virus, large accumulations of viral antigen and RNA and comprised 17 of 17,825 (0.09% of assayed mosquitoes, 2 infected mosquitoes (I+ contained no detectable infectious virus, lesser amounts of viral antigen and RNA, and comprised 3.7% of mosquitoes, and 3 non-infected mosquitoes (I- contained no detectable viral antigen, RNA, or infectious virus and comprised 96.21% of mosquitoes. SI+ mosquitoes were recovered in consecutive years at one field site, suggesting that lineages of TOT stably-infected and geographically isolated Ae. triseriatus exist in nature. Analyses of LACV genomes showed that SI+ isolates are not monophyletic nor phylogenetically distinct and that synonymous substitution rates exceed replacement rates in all genes and isolates. Analysis of singleton versus shared mutations (Fu and Li's F* revealed that the SI+ LACV M segment, with a large and significant excess of intermediate-frequency alleles, evolves through disruptive selection that maintains SI+ alleles at higher frequencies than the average mutation rate. A QTN in the LACV NSm gene was detected in SI+ mosquitoes, but not in I+ mosquitoes. Four amino acid changes were detected in the LACV NSm gene from SI+ but not I+ mosquitoes from one site, and may condition vector super infection. In contrast to NSm, the NSs sequences of LACV from SI+ and I+ mosquitoes were identical. Conclusions SI+ mosquitoes may represent

  17. Electron impact ionization of cycloalkanes, aldehydes, and ketones

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Dhanoj; Antony, Bobby, E-mail: bka.ism@gmail.com [Department of Applied Physics, Indian School of Mines, Dhanbad, JH 826 004 (India)

    2014-08-07

    The theoretical calculations of electron impact total ionization cross section for cycloalkane, aldehyde, and ketone group molecules are undertaken from ionization threshold to 2 keV. The present calculations are based on the spherical complex optical potential formalism and complex scattering potential ionization contribution method. The results of most of the targets studied compare fairly well with the recent measurements, wherever available and the cross sections for many targets are predicted for the first time. The correlation between the peak of ionization cross sections with number of target electrons and target parameters is also reported. It was found that the cross sections at their maximum depend linearly with the number of target electrons and with other target parameters, confirming the consistency of the values reported here.

  18. Electron-impact ionization of heavy atomic ions

    International Nuclear Information System (INIS)

    Pindzola, M.S.; Griffin, D.C.; Bottcher, C.

    1987-01-01

    General theoretical methods for the calculation of direct and indirect processes in the electron-impact ionization of heavy atomic ions are reviewed. Cross section results for Xe 8+ and U 89+ are presented. 12 refs., 4 figs

  19. Improvements in ionization chambers

    International Nuclear Information System (INIS)

    Whetten, N.R.; Zubal, C.

    1980-01-01

    A method of reducing mechanical vibrations transmitted to the parallel plate electrodes of ionization chamber x-ray detectors, commonly used in computerized x-ray axial tomography systems, is described. The metal plate cathodes and anodes are mounted in the ionizable gas on dielectric sheet insulators consisting of a composite of silicone resin and glass fibres. (UK)

  20. Dual ionization chamber

    International Nuclear Information System (INIS)

    Mallory, J.; Turlej, Z.

    1981-01-01

    Dual ionization chambers are provided for use with an electronic smoke detector. The chambers are separated by electrically-conductive partition. A single radiation source extends through the partition into both chambers, ionizing the air in each. The mid-point current of the device may be balanced by adjusting the position of the source

  1. Electron impact ionization of the gas-phase sorbitol

    Science.gov (United States)

    Chernyshova, Irina; Markush, Pavlo; Zavilopulo, Anatoly; Shpenik, Otto

    2015-03-01

    Ionization and dissociative ionization of the sorbitol molecule by electron impact have been studied using two different experimental methods. In the mass range of m/ z = 10-190, the mass spectra of sorbitol were recorded at the ionizing electron energies of 70 and 30 eV. The ion yield curves for the fragment ions have been analyzed and the appearance energies of these ions have been determined. The relative total ionization cross section of the sorbitol molecule was measured using monoenergetic electron beam. Possible fragmentation pathways for the sorbitol molecule were proposed.

  2. Electron-impact ionization of Mo+

    International Nuclear Information System (INIS)

    Ludlow, J.A.; Loch, S.D.; Pindzola, M.S.

    2005-01-01

    The electron-impact direct ionization cross section for Mo + is calculated using both nonperturbative close-coupling and perturbative distorted-wave methods. When distorted-wave calculations for 4d 5 →4d 4 direct ionization are added to distorted-wave calculations for 4p→nl excitation-autoionization, the experimental measurements are found to be 60% lower than the theoretical predictions. Inclusion of nonperturbative three-body Coulomb effects, present in time-dependent close-coupling calculations, are found to reduce the distorted-wave 4d 5 →4d 4 direct ionization cross section by 25%. This is by far the largest reduction yet seen when comparing the two methods for direct subshell ionization of an atomic positive ion in the ground state. However, when the close-coupling calculations for 4d 5 →4d 4 direct ionization are added to distorted-wave calculations for 4p→nl excitation-autoionization, the experimental measurements are still 45% lower than the theoretical predictions. Although we further investigate correlation effects in the initial target state and term-dependent potential effects in the ejected electron state in an attempt to understand the small magnitude of the experimental measurements, the discrepancy between theory and experiment remains unexplained

  3. Resonantly enhanced collisional ionization measurements of radionuclides

    International Nuclear Information System (INIS)

    Whitaker, T.J.; Bushaw, B.A.; Gerke, G.K.

    1986-01-01

    The authors developed a new laser technique to analyze for radionuclides at extremely low levels. The technique, called resonantly enhanced collisional ionization (RECI), uses two nitrogen-laser pumped dye lasers to excite the target isotope to a high-energy Rydberg state. Atoms in these Rydberg states (within a few hundred wavenumbers in energy from the ionization threshold) efficiently ionize upon colliding with an inert gas and the ions can be detected by conventional means. The principal advantage of resonantly-enhanced collisional ionization is the extreme sensitivity coupled with its relative simplicity and low cost. Actinides typically have an ionization potential of about 6eV (uranium I.P. = 6.2 eV, plutonium I.P. = 5.7 eV). Two-step laser excitation to a state just below threshold requires wavelengths in the blue region of the visible spectrum. They showed that when both steps in the excitation process are resonant steps, relatively low-power lasers can populate the Rydberg state with almost unit efficiency. This is because the resonant excitations have much larger cross-sections than do photoionization processes. They also demonstrated that a few torr of a buffer gas will cause most of the excited-state atoms to be ionized

  4. Properties of partially ionized hydrogen plasmas in high electric fields

    International Nuclear Information System (INIS)

    Morawetz, K.

    1993-03-01

    In this thesis the fundamental equations of many-particle quantum-statistics of nonequilibrium are treated in respect to arbitrary high electric fields. Generalizations are found for the T-matrix approximation as well as for the shielded potential approximation valid for any field strength. These result in a non-Markovian behavior of the obtained collision integrals, also known as intra-collisional-field-effect (ICFE), and in a broadening of the energy conservation, the so-called collisional broadening (CB), caused by applied electric fields. In linear response it is shown in a new way, how the Debye-Onsager relaxation effect can be rederived from these collision integrals. Furthermore the complete quantum result is presented. Both effects, ICFE and CB, contribute to the right classical limit. The quantum result yields an surprising maximum of this field effects in dependence of the interacting mass ratio, which may be important in exciton-plasmas and semiconductors. (orig.)

  5. Partially ionized plasmas including the third symposium on uranium plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, M. [ed.

    1976-09-01

    Separate abstracts are included for 28 papers on electrically generated plasmas, fission generated plasmas, nuclear pumped lasers, gaseous fuel reactor research, and applications. Five papers have been previously abstracted and included in ERA.

  6. Introduction to ionizing radiation physics

    International Nuclear Information System (INIS)

    Musilek, L.

    1979-01-01

    Basic properties are described of the atom, atomic nucleus and of ionizing radiation particles; nuclear reactions, ionizing radiation sources and ionizing radiation interaction with matter are explained. (J.P.)

  7. Valence shell photoionization energies and cross-sections of NF sub 3 and PF sub 3

    CERN Document Server

    Jürgensen, A

    2003-01-01

    Relative outer valence shell ionization potentials and cross-sections were determined for the isostructural, Group 15, trifluorides NF sub 3 and PF sub 3 in the gas phase using synchrotron radiation. Excitation photon energies ranged from 70 to 160 eV. The experimental spectra were assigned and cross-sections analyzed with the aid of both MS-X alpha and ab initio calculations. Spectral differences in peak energies and relative intensities are related to structural and electronic differences between these two fluoride molecules. Valence shell ionization potentials were compared to calculated values obtained by several different methods. The partial photoionization cross-sections for each orbital were obtained as a function of excitation energy and compared to theoretical results obtained with the X alpha method.

  8. Biological Effects of Ionizing Radiation

    Science.gov (United States)

    Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.

    1952-04-07

    This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.

  9. Strong suppression of the positronium channel in double ionization of noble gases by positron impact

    DEFF Research Database (Denmark)

    Bluhme, H.; Knudsen, H.; Merrison, J.P.

    1998-01-01

    Positron-induced double ionization of helium and neon has been studied at energies from threshold to 900 eV. A remarkable difference between the near-threshold behavior of the single and double ionization cross sections is found: Single ionization is dominated by positronium (Ps) formation, while...

  10. Near-Threshold Ionization of Argon by Positron Impact

    Science.gov (United States)

    Babij, T. J.; Machacek, J. R.; Murtagh, D. J.; Buckman, S. J.; Sullivan, J. P.

    2018-03-01

    The direct single-ionization cross section for Ar by positron impact has been measured in the region above the first ionization threshold. These measurements are compared to semiclassical calculations which give rise to a power law variation of the cross section in the threshold region. The experimental results appear to be in disagreement with extensions to the Wannier theory applied to positron impact ionization, with a smaller exponent than that calculated by most previous works. In fact, in this work, we see no difference in threshold behavior between the positron and electron cases. Possible reasons for this discrepancy are discussed.

  11. Calculation of ionization within the close-coupling formalism

    International Nuclear Information System (INIS)

    Bray, I.; Fursa, D.V.

    1996-05-01

    A method for calculation of differential ionization cross sections from theories that use the close-coupling expansions for the total wave functions is presented. It is shown how from a single such calculation elastic, excitation, and ionization cross sections may be extracted using solely the T-matrix elements arising from solution of the coupled equations. To demonstrate the applicability of this formalism, the convergent close-coupling (CCC) theory is systematically applied at incident energies of 150-600 eV to the calculation of e-He ionization. Comparison with available measurements is generally very good. 50 refs., 17 figs

  12. Double ionization of atomic helium under heavy ion impact

    International Nuclear Information System (INIS)

    Presnyakov, L.P.; Uskov, D.B.

    1995-01-01

    Cross sections for double ionization of helium by multiply-charged ion impact and the corresponding ratios of double-to-single ionization are presented as a sum of the contributions given by the one-step (shake-off) and two-step (TS) processes. An analytic form is found for the continuum wavefunction which is valid in both limiting cases of low and high velocities of the relative motion. Using this wavefunction, the TS cross sections are calculated within the independent-event model. The results for the ratios of double-to-single ionization show satisfactory agreement with the experimental data available. (author)

  13. Ionization of atoms by high energy photons

    International Nuclear Information System (INIS)

    Amusia, M.Y.; Ioffe, A.F.

    1994-01-01

    Photoionization of atoms by high energy photons is considered. It is emphasized that in this frequency region the cross section and other characteristics of the process are strongly effected by electron shell polarization and rearrangement effects, including that due to inner vacancy Auger decay. In the effects of nuclear structure could be important and noticeable, i.e. of virtual or real excitation of the nucleus degrees of freedom and of the Quantum Electrodynamics vacuum. Ionization accompanied by secondary photon emission (Compton ionization) is analyzed in the considered domain of energies

  14. Double differential cross sections of ethane molecule

    Science.gov (United States)

    Kumar, Rajeev

    2018-05-01

    Partial and total double differential cross sections corresponding to various cations C2H6+, C2H4+, C2H5+, C2H3+, C2H2+, CH3+, H+, CH2+, C2H+, H2+, CH+, H3+, C2+ and C+ produced during the direct and dissociative electron ionization of Ethane (C2H6) molecule have been calculated at fixed impinging electron energies 200 and 500eV by using modified Jain-Khare semi empirical approach. The calculation for double differential cross sections is made as a function of energy loss suffered by primary electron and angle of incident. To the best of my knowledge no other data is available for the comparison.

  15. Antioxidant Approaches to Management of Ionizing Irradiation Injury

    Directory of Open Access Journals (Sweden)

    Joel Greenberger

    2015-01-01

    Full Text Available Ionizing irradiation induces acute and chronic injury to tissues and organs. Applications of antioxidant therapies for the management of ionizing irradiation injury fall into three categories: (1 radiation counter measures against total or partial body irradiation; (2 normal tissue protection against acute organ specific ionizing irradiation injury; and (3 prevention of chronic/late radiation tissue and organ injury. The development of antioxidant therapies to ameliorate ionizing irradiation injury began with initial studies on gene therapy using Manganese Superoxide Dismutase (MnSOD transgene approaches and evolved into applications of small molecule radiation protectors and mitigators. The understanding of the multiple steps in ionizing radiation-induced cellular, tissue, and organ injury, as well as total body effects is required to optimize the use of antioxidant therapies, and to sequence such approaches with targeted therapies for the multiple steps in the irradiation damage response.

  16. Meas.of the Ratio Between Double and Single Ionization of Helium for Antiprotons

    CERN Multimedia

    2002-01-01

    The aim of this experiment is to measure the ratio between double and single ionization of helium by antiprotons in the energy range $>$~3~MeV. Comparison with already existing proton data will yield information on the mechanisms for double ionization, which could not be extracted from previous comparisons between ratios measured for equivelocity electrons and protons. The most basic information to be obtained from an antiproton experiment will be the amount of correlation existing between the two electrons in the ground-state helium atom.\\\\ \\\\ The equipment consists of a gas cell, which employs slow-ion collection via the so-called condenser-plate method for the absolute sum of partial-ionization cross sections and determination of the relative contribution of multiple charged ions by TOF. The gas cell has movable entrance and exit slits and a grid system to account for secondary emission from the collection of slow ions. Together with a field of 800~V/cm in the collision region, the potentials of the TOF sp...

  17. Miniature ionization chamber

    International Nuclear Information System (INIS)

    Alexeev, V.I.; Emelyanov, I.Y.; Ivanov, V.M.; Konstantinov, L.V.; Lysikov, B.V.; Postnikov, V.V.; Rybakov, J.V.

    1976-01-01

    A miniature ionization chamber having a gas-filled housing which accommodates a guard electrode made in the form of a hollow perforated cylinder is described. The cylinder is electrically associated with the intermediate coaxial conductor of a triaxial cable used as the lead-in of the ionization chamber. The gas-filled housing of the ionization chamber also accommodates a collecting electrode shaped as a rod electrically connected to the center conductor of the cable and to tubular members. The rod is disposed internally of the guard electrode and is electrically connected, by means of jumpers passing through the holes in the guard electrode, to the tubular members. The tubular members embrace the guard electrode and are spaced a certain distance apart along its entire length. Arranged intermediate of these tubular members are spacers secured to the guard electrode and fixing the collecting electrode throughout its length with respect to the housing of the ionization chamber

  18. What is ''ionizing radiation''?

    International Nuclear Information System (INIS)

    Tschurlovits, M.

    1997-01-01

    The scientific background of radiation protection and hence ''ionizing radiation'' is undergoing substantial regress since a century. Radiations as we are concerned with are from the beginning defined based upon their effects rather than upon the physical origin and their properties. This might be one of the reasons why the definition of the term ''ionizing radiation'' in radiation protection is still weak from an up to date point of view in texts as well as in international and national standards. The general meaning is unambiguous, but a numerical value depends on a number of conditions and the purpose. Hence, a clear statement on a numerical value of the energy threshold beyond a radiation has to be considered as ''ionizing'' is still missing. The existing definitions are, therefore, either correct but very general or theoretical and hence not applicable. This paper reviews existing definitions and suggests some issues to be taken into account for possible improvement of the definition of ''ionizing radiation''. (author)

  19. Ionization particle detector

    International Nuclear Information System (INIS)

    Ried, L.

    1982-01-01

    A new device is claimed for detecting particles in a gas. The invention comprises a low cost, easy to assemble, and highly accurate particle detector using a single ionization chamber to contain a reference region and a sensing region. The chamber is designed with the radioactive source near one electrode and the second electrode located at a distance less than the distance of maximum ionization from the radioactive source

  20. Structure of electron tracks in water. 2. Distribution of primary ionizations and excitations in water radiolysis

    International Nuclear Information System (INIS)

    Pimblott, S.M.; Mozumder, A.

    1991-01-01

    A procedure for the calculation of entity-specific ionization and excitation probabilities for water radiolysis at low linear energy transfer (LET) has been developed. The technique pays due attention to the effects of the ionization threshold and the energy dependence of the ionization efficiency. The numbers of primary ionizations and excitations are not directly proportional to the spur energy. At a given spur energy, ionization follows a binomial distribution subject to an energetically possible maximum. The excitation distribution for a spur of given energy and with a given number of ionizations is given by a geometric series. The occurrence probabilities depend upon the cross sections of ionization, excitation, and other inferior processes. Following the low-LET radiolysis of liquid water the most probable spurs contain one ionization, two ionizations, or one ionization and one excitation, while in water vapor they contain either one ionization or one excitation. In liquid water the most probable outcomes for spurs corresponding to the most probable energy loss (22 eV) and to the mean energy loss (38 eV) are one ionization and one excitation, and two ionizations and one excitation, respectively. In the vapor, the most probable energy loss is 14 eV which results in one ionization or one excitation and the mean energy loss is 34 eV for which the spur of maximum probability contains one ionization and two excitations. The total calculated primary yields for low-LET radiolysis are in approximate agreement with experiment in both phases

  1. The ratio of double to single ionization of helium: The relationship of photon and bare charged particle impact ionization

    International Nuclear Information System (INIS)

    Manson, S.T.

    1994-01-01

    In this paper the author derives expressions for the ratio of double to single ionization of helium from its ground state, by both single photons, and charged particle impact. He shows that in the limit of large reduced incident energy T of a charged particle, that the ratio of the double to single ionization cross sections at some energy transfer ΔE is equal to the ratio of photoionization cross sections for a photon of energy hν = ΔE, independent of T. He then goes on to find a relationship for this ionization ratio which is not restricted to some specific energy transfer, and shows that the double to single ionization cross section ratio approaches an asymtotic limit for large enough T

  2. Charge transfer and ionization occurring in proton- and helium ion-atom collisions

    International Nuclear Information System (INIS)

    DuBois, R.D.

    1985-12-01

    Two examples are presented where specific channels have been identified that are responsible for single and double target ionization via direct coulomb ionization or charge transfer processes. Using ratios of absolute cross sections that have been measured for these processes it was shown that an independent electron model should be appropriate for calculating direct double target ionization but generally appears to be inadequate in calculating charge transfer plus ionization and double charge transfer cross sections. At present such detailed information can be obtained only in limited cases. However cross sections with detailed final charge state information should provide stringent tests for present and future theoretical work. 22 refs., 2 figs

  3. Efficient ionizer for polarized H- formation

    International Nuclear Information System (INIS)

    Alessi, J.G.

    1985-01-01

    An ionizer is under development for a polarized H - source based on the resonant charge exchange reaction polarized H 0 + D - → polarized H - + D 0 . The polarized H 0 beam passes through the center of a magnetron surface-plasma source having an annular geometry, where it crosses a high current (approx.0.5 A), 200 eV D - beam. Calculations predict an H 0 → H - ionization efficiency of approx.7%, more than an order of magnitude higher than that obtained on present ground state atomic beam sources. In initial experiments using an unpolarized H 0 beam, H - currents in excess of 100 μA have been measured. While the ionization efficiency is now only about the same as other methods (Cs beam, for example), the results are encouraging since it appears that by injecting positive ions to improve the space-charge neutralization, and by improving the extraction optics, considerable gains in intensity will be made. We will then use this ionizer with a polarized H 0 beam, and measure the polarization of the resulting H - beam. If no depolarization is observed this ionizer will be combined with an atomic beam, cooled to 5 to 6 K, to give a polarized H - beam expected to be in the milliampere range for use in the AGS

  4. Effects of autoionizing states on two-photon double ionization of the H2 molecule

    International Nuclear Information System (INIS)

    Guan, Xiaoxu; Bartschat, Klaus; Koesterke, Lars; Schneider, Barry I

    2014-01-01

    We report angle-resolved and angle-integrated cross sections for two-photon double-ionization of H by a strong laser pulse. The effect of doubly excited states on the predicted cross sections is addressed.

  5. Ionizing radiations in food industry

    International Nuclear Information System (INIS)

    Adamo, M.; Tata, A.

    1999-01-01

    Foodstuffs treatment by ionization is able to produce both a shelf-life extension and/or a food borne diseases control through the pathogenic population reduction/elimination. The main process goal is to ensure the hygienic quality and the wholesomeness of products to be marketed, in order to limit food borne diseases originated mainly through the cross contamination process. In fact several products may contain pathogenic agents or bacteria (e.g. Salmonella and Campylbacter in poultry meat), whose associated pathologies are world-wide increasing. At present, over 40 countries provide clearances for the treatment of about 45 different types of foodstuffs and in over 20 of them the ionizing process is already industrially utilized for spices, poultry, shrimps and vegetables. As it refers to process economic aspects, market researches have shown cost figures ranging from few tens to some hundreds Lit/kg, depending on the dose to products. The costs are competitive with alternative treatments, beyond the recovery of economic productivity reduction caused by food borne diseases

  6. Cruzamento dialélico parcial entre variedades locais do Paraná e variedades sintéticas de milho Partial dialell cross between landraces from Paraná and synthetic varieties of maize

    Directory of Open Access Journals (Sweden)

    Vanessa Kostetzer

    2009-09-01

    Full Text Available Os objetivos deste trabalho foram determinar as capacidades geral e específica de combinação entre variedades locais e sintéticas de milho e identificar cruzamentos que reúnam características de interesse agronômico, com vistas à síntese de variedades. O dialelo parcial foi realizado com 11 variedades sintéticas cruzadas com cinco variedades locais do Paraná. As combinações híbridas resultantes foram avaliadas juntamente com as cinco variedades locais genitoras e com cinco híbridos comerciais, em blocos completos ao acaso com quatro repetições, em São João do Triunfo e Londrina, PR. Houve interação genótipo x local para a maioria dos caracteres avaliados, com predominância da interação da capacidade geral de combinação x local. As melhores estimativas de capacidade geral de combinação do grupo dos sintéticos foram observadas para ST09 e ST04 e, no grupo das variedades, para MC45 e IAPAR 50, considerando-se o conjunto das características e de locais. As melhores combinações híbridas (MC34 x ST04, IAPAR 50 x ST07, MC47 x ST09, MC45 x ST02, MC51 x ST04 e MC45 x ST01 apresentaram estimativas positivas de capacidade específica de combinação quanto à produtividade, em ambos os locais. Existem combinações híbridas com potencial para síntese de novas variedades com padrões de produtividade, altura de planta, posição relativa da espiga e percentagem de espigas danificadas e de plantas acamadas e quebradas melhores que os observados em variedades locais per se e mais semelhantes aos dos híbridos comerciais.The objectives of this work were to determine the general and specific combining ability between landraces and synthetic varieties of maize and to identify the crosses that combine important agronomic traits, to develop new maize varieties. A partial diallel was done with 11 synthetic varieties crossed with five landraces. The crosses were evaluated along with the five parental landraces and five commercial

  7. Partial dynamical systems, fell bundles and applications

    CERN Document Server

    Exel, Ruy

    2017-01-01

    Partial dynamical systems, originally developed as a tool to study algebras of operators in Hilbert spaces, has recently become an important branch of algebra. Its most powerful results allow for understanding structural properties of algebras, both in the purely algebraic and in the C*-contexts, in terms of the dynamical properties of certain systems which are often hiding behind algebraic structures. The first indication that the study of an algebra using partial dynamical systems may be helpful is the presence of a grading. While the usual theory of graded algebras often requires gradings to be saturated, the theory of partial dynamical systems is especially well suited to treat nonsaturated graded algebras which are in fact the source of the notion of "partiality". One of the main results of the book states that every graded algebra satisfying suitable conditions may be reconstructed from a partial dynamical system via a process called the partial crossed product. Running in parallel with partial dynamica...

  8. Molecular Data for a Biochemical Model of DNA Radiation Damage: Electron Impact Ionization and Dissociative Ionization of DNA Bases and Sugar-Phosphate Backbone

    Science.gov (United States)

    Dateo, Christopher E.; Fletcher, Graham D.

    2004-01-01

    As part of the database for building up a biochemical model of DNA radiation damage, electron impact ionization cross sections of sugar-phosphate backbone and DNA bases have been calculated using the improved binary-encounter dipole (iBED) model. It is found that the total ionization cross sections of C3'- and C5'-deoxyribose-phospate, two conformers of the sugar-phosphate backbone, are close to each other. Furthermore, the sum of the ionization cross sections of the separate deoxyribose and phosphate fragments is in close agreement with the C3'- and C5'-deoxyribose-phospate cross sections, differing by less than 10%. Of the four DNA bases, the ionization cross section of guanine is the largest, then in decreasing order, adenine, thymine, and cytosine. The order is in accordance with the known propensity of oxidation of the bases by ionizing radiation. Dissociative ionization (DI), a process that both ionizes and dissociates a molecule, is investigated for cytosine. The DI cross section for the formation of H and (cytosine-Hl)(+), with the cytosine ion losing H at the 1 position, is also reported. The threshold of this process is calculated to be 17.1 eV. Detailed analysis of ionization products such as in DI is important to trace the sequential steps in the biochemical process of DNA damage.

  9. Coupled-channels calculations of excitation and ionization in ion-atom collisions

    International Nuclear Information System (INIS)

    Martir, M.H.

    1981-01-01

    A numerical method has been used to compute excitation and ionization cross sections for ion-atom collisions. The projectile is treated classically and follows a straight line, constant velocity path (unless indicated otherwise). The wave function that describes the atom is expanded about the target in a truncated Hilbert space. The interaction between the projectile and the target atom is treated as a time dependent perturbation. A unitary time development operator, U, propagates the wave function from a time prior to the collision to a time after the collision in small time steps. Contrary to first-order theories, coupling between states is allowed. This method has been improved so that any number of partial waves can be included in the wave function expansion. This method has been applied to study negatively charged projectiles. Cross sections are obtained for collisions of antiprotons on atomic hydrogen (30 keV to 372 keV) and compared with cross sections of protons on atomic hydrogen to explore the Z/sub P/ dependence. The antiproton-hydrogen results were converted into electron-hydrogen values with E/sub e/ = E/sub P/(m/sub e//m/sub P/) (15 eV to 200 eV) and compared to experimental values. The method is then applied to study vacancy production from the L-shell. The partial wave convergence of the cross sections was carefully studied for s through g waves. Collisions between protons (and alpha-particles) and argon are studied to explore the Z/sub P/ dependence of the cross sections. The cross section ratio sigma(α)/(4sigma(p)) is compared to experiment

  10. CTMC calculation of Si2+ + H impact ionization

    International Nuclear Information System (INIS)

    Liu Chunlei; He Bin; Ning Ye; Yan Jun; Wang Jianguo

    2005-01-01

    The Si 2+ + H collision ionization is studied using classical trajectory Monte-Carlo (CTMC) method. The total cross section as functions of the energy of incident projectile, single differential cross section and double differential cross section as a functions of the energy and the angle of the ejected electron are calculated. The ionization mechanisms of soft collision, electron capture to the continuum state, binary encounter collision are demonstrated. The effect of 'saddle point' is also discussed by calculating the ejected electron distribution depending on the ratios of distances between electron and target and between electron and projectile. (author)

  11. The critical ionization velocity

    International Nuclear Information System (INIS)

    Raadu, M.A.

    1980-06-01

    The critical ionization velocity effect was first proposed in the context of space plasmas. This effect occurs for a neutral gas moving through a magnetized plasma and leads to rapid ionization and braking of the relative motion when a marginal velocity, 'the critical velocity', is exceeded. Laboratory experiments have clearly established the significance of the critical velocity and have provided evidence for an underlying mechanism which relies on the combined action of electron impact ionization and a collective plasma interaction heating electrons. There is experimental support for such a mechanism based on the heating of electrons by the modified two-stream instability as part of a feedback process. Several applications to space plasmas have been proposed and the possibility of space experiments has been discussed. (author)

  12. Ionization front accelerator

    International Nuclear Information System (INIS)

    Olson, C.L.

    1975-01-01

    In a recently proposed linear collective accelerator, ions are accelerated in a steep, moving potential well created at the head of an intense relativistic electron beam. The steepness of the potential well and its motion are controlled by the external ionization of a suitable background gas. Calculations concerning optimum choices for the background gas and the ionization method are presented; a two-step photoionization process employing Cs vapor is proposed. In this process, a super-radiant light source is used to excite the gas, and a UV laser is used to photoionize the excited state. The appropriate line widths and coupled ionization growth rate equations are discussed. Parameter estimates are given for a feasibility experiment, for a 1 GeV proton accelerator, and for a heavy ion accelerator (50 MeV/nucleon uranium). (auth)

  13. The ionizing treatment of food

    International Nuclear Information System (INIS)

    1998-01-01

    This book of proceedings contains the talks given by the members of the Society of chemical experts of France (SECF) and by various specialists of the ionizing treatment during the scientific days of September 25-26, 1997. The aim of this meeting was to reconsider the effects of ionization from a scientific point of view and apart from the polemics generated by this domain. The following topics were discussed successively: source and characterization of a ionizing treatment, biological effects of ionization on food and the expected consequences, the ionizing treatment and the reduction of the vitamin C content of fruits and vegetables, is it safe to eat irradiated food?, the organoleptic modifications of food after ionization, quality assurance of dosimetry measurements in an industrial installation of food ionization, the French and European regulations in food ionization, the detection of irradiated foodstuffs, processed food and complex lipid matrices, sterilization of dishes for immuno-depressed patients using ionization. (J.S.)

  14. Endoergic chemi-ionization in N-O collisions

    International Nuclear Information System (INIS)

    Nielsen, S.E.; Dahler, J.S.

    1979-01-01

    A semiclassical theory of endoergic chemi-ionization is developed and applied to the ionizing events that occur when ground state oxygen atoms collide with nitrogen atoms in the ground and first excited states. The approach used is an adaptation and extension of earlier theories due to Bardsley, Nakamura, and Miller. The theory relates the experimental associative (AI) and Penning ionization (PI) cross sections to the following events: formation of a stable diatomic ion (AI), neutral and ionized atomic fragments (PI), or of a metastable diatomic rotational resonance (DI, delayed ionization). The heavy particle motions are treated classically in terms of adiabatic potential energy functions, while localized nonadiabatic transitions also are taken into account by using the Landau-Zener approximation. Finally, the theoretical predictions compare well with the results of Ringer and Gentry's (1978) merged beam experiments

  15. Ambient ionization mass spectrometry

    International Nuclear Information System (INIS)

    Lebedev, A T

    2015-01-01

    Ambient ionization mass spectrometry emerged as a new scientific discipline only about ten years ago. A considerable body of information has been reported since that time. Keeping the sensitivity, performance and informativity of classical mass spectrometry methods, the new approach made it possible to eliminate laborious sample preparation procedures and triggered the development of miniaturized instruments to work directly in the field. The review concerns the theoretical foundations and design of ambient ionization methods. Their advantages and drawbacks, as well as prospects for application in chemistry, biology, medicine, environmetal analysis, etc., are discussed. The bibliography includes 194 references

  16. Liquid ionizing radiaion detector

    International Nuclear Information System (INIS)

    deGaston, A.N.

    1979-01-01

    A normally nonconducting liquid such as liquid hydrocarbon is encased between a pair of electrodes in an enclosure so that when the liquid is subjected to ionizing radiation, the ion pairs so created measurably increase the conductivity of the fluid. The reduced impedance between the electrodes is detectable with a sensitive ohm-meter and indicates the amount of ionizing radiation. The enclosure, the electrodes and the fluid can be constructed of materials that make the response of the detector suitable for calibrating a large range of radiation energy levels. The detector is especially useful in medical applications where tissue equivalent X ray detectors are desired

  17. Radiation dependent ionization model

    International Nuclear Information System (INIS)

    Busquet, M.

    1991-01-01

    For laser created plasma simulation, hydrodynamics codes need a non-LTE atomic physics package for both EOS and optical properties (emissivity and opacity). However in XRL targets as in some ICF targets, high Z material can be found. In these cases radiation trapping can induce a significant departure from the optically thin ionization description. The authors present a method to change an existing LTE code into a non-LTE code with coupling of ionization to radiation. This method has very low CPU cost and can be used in 2D simulations

  18. Contact ionization ion source

    International Nuclear Information System (INIS)

    Hashmi, N.; Van Der Houven Van Oordt, A.J.

    1975-01-01

    An ion source in which an apertured or foraminous electrode having a multiplicity of openings is spaced from one or more active surfaces of an ionisation electrode, the active surfaces comprising a material capable of ionising by contact ionization a substance to be ionized supplied during operation to the active surface or surfaces comprises means for producing during operation a magnetic field which enables a stable plasma to be formed in the space between the active surface or surfaces and the apertured electrode, the field strength of the magnetic field being preferably in the range between 2 and 8 kilogauss. (U.S.)

  19. Evaluation of intervarietal maize hybrids through partial diallel cross, considering four environments/ Avaliação de híbridos intervarietais de milho por meio de cruzamento dialélico parcial, considerando quatro ambientes

    Directory of Open Access Journals (Sweden)

    Pedro Mário de Araújo

    2006-06-01

    Full Text Available In the summer season of 2004/2005, 12 intervarietal maize hybrids, crossed by the partial diallel scheme 3 x 4, the seven parental populations and three checks were evaluated at Iapar Experimental Stations in Londrina, Pato Branco, Ponta Grossa e Guarapuava. The objective was to identify crosses for future work with recurrent selection, inbred lines extraction and composite synthesis. For Heterosis variation cause, the differences were determined (PForam avaliados 12 híbridos intervarietais de milho (Zea mays L., cruzados em esquema dialélico parcial 3 x 4 mais as sete populações parentais e 3 testemunhas. Os ensaios foram implantados nas estações experimentais do Iapar em Londrina, Pato Branco, Ponta Grossa e Guarapuava. O objetivo foi avaliar um conjunto de sete populações no sentido de se estimar parâmetros que venham a auxiliar na escolha de materiais para posteriores trabalhos com seleção recorrente, extração de linhagens e síntese de compostos. Para a fonte Heterose as diferenças foram constatadas (p < 0,01 para as variáveis produtividade de grãos e florescimento feminino, indicando que os cruzamentos foram superiores aos pais. Em relação aos valores de Capacidade Geral de Combinação para rendimento, os parentais do grupo-1, PC 9407 e BR 106, obtiveram como valores 36,7 e 171,1 kg.ha-1, respectivamente, e os parentais do grupos-2, PC 9701 e PC 9502, apresentaram valores de 131,1 e 56,8 kg.ha-1, respectivamente,. Para a Capacidade Específica de Combinação, os maiores valores foram para PC 9701 x BR 106 (205,4 kg.ha-1 e PC 9502 x PC 9407 (135,3 kg.ha-1, assim como as maiores médias de produtividade de grãos dos cruzamentos avaliados (9.297 e 9.018 kg.ha-1, respectivamente. As populações PC 9701, BR 106, PC 9502 e PC 9407 são promissoras fontes para a extração de linhagens visando desenvolvimento de híbridos, síntese de compostos e trabalhos com seleção recorrente.

  20. Data on ionization, excitation, dissociation and dissociative ionization of targets by helium ion bombardments, (1)

    International Nuclear Information System (INIS)

    Oda, Nobuo; Urakawa, Junji

    1984-03-01

    This report presents a compilation of the experimental data on cross sections for the ionization, excitation, dissociation and dissociative ionization processes of targets in helium ion impacts on atoms and molecules under a single collision condition. These measurements were carried out in the energy range from several keV to 3.5 MeV. A systematic survey has been made on the literatures from 1975 to the end of 1982. A list of references is also given, including relevant papers published before 1975. (author)

  1. Social determinants and lifestyle risk factors only partially explain the higher prevalence of food insecurity among Aboriginal and Torres Strait Islanders in the Australian state of Victoria: a cross-sectional study

    Science.gov (United States)

    2014-01-01

    Background The prevalence of food insecurity is substantially higher among Australians of Aboriginal or Torres Strait Islander descent. The purpose of this study is to explain the relationship between food insecurity and Aboriginal and Torres Islander status in the state of Victoria. Methods Data were obtained from the 2008 Victorian Population Health Survey; a cross-sectional landline computer-assisted telephone interview survey of 34,168 randomly selected Victorians aged 18 years and older; including 339 Aboriginal and Torres Strait Islanders. We categorised a respondent as food insecure, if in the previous 12 months, they reported having run out of food and not being able to afford to buy more. We used multivariable logistic regression to adjust for age, sex, socioeconomic status (household income), lifestyle risk factors (smoking, alcohol consumption and obesity), social support (ability to get help from family, friends or neighbours), household composition (lone parent status, household with a child, and household size), and geographic location (rurality). Results Aboriginal and Torres Strait Islanders (20.3%) were more likely than their non-Aboriginal and Torres Strait Islander counterparts (5.4%) to have experienced food insecurity; odds ratio (OR) = 4.5 (95% CI; 2.7-7.4). Controlling for age, SES, smoking, obesity and inability to get help from family or friends reduced the odds ratio by 38%; ORadjusted = 2.8 (1.6-5.0). Conclusions Social determinants and lifestyle risk factors only partially explained the higher prevalence of food insecurity among Aboriginal and Torres Strait Islanders in Victoria. Further research is needed to explain the disparity in food insecurity between the two populations in order to inform and guide corrective action. PMID:24924598

  2. Indirect processes in electron impact ionization of Kr24+ and Kr25+

    International Nuclear Information System (INIS)

    Chen, M.H.; Reed, K.J.

    1992-09-01

    Electron-impact ionization cross sections have been calculated for magnesiumlike Kr 24+ and sodiumlike Kr 25+ . Electron-impact ionization is an important atomic process in hot dense plasmas. It can affect the ionization balance, electron temperature, electron density, and level population in the plasma. In the past decade, theoretical and experimental studies have revealed that indirect processes can make significant contributions to the cross sections for electron impact ionization of positive ions. The most important indirect process is excitation of an inner-shell electron followed by Auger emission. Higher-order processes such as resonant excitation followed by sequential double Auger emission, can also contribute significantly. The contributions of excitation-autoionization and resonant excitation double autoionization (REDA) were included, in addition to the cross sections for direct ionization of a 3s electron. The calculations were carried out using the relativistic distorted wave methods and the multiconfiguration Dirac-Fock model. For Kr 25+ , the total cross section is about 5 times the direct ionization cross section. For the Kr 24+ , the indirect contribution is about 2.5 times the direct ionization cross section. The REDA process produces many strong resonances and contributes about 20% to the average ionization cross section

  3. Detection of ionized foods

    International Nuclear Information System (INIS)

    Beerens, H.

    1986-01-01

    Irradiated foods and feed might be identified with two kinds of tests: 1. biochemical: detection of specific products are not yet available 2. microbiological: when a microbial species dissapears from a sample of food i.e. it is not detectable after enrichment (for instance Coliforms in hamburgers) it is likely that the sample has been ionized [fr

  4. Ionization loss in BGO

    International Nuclear Information System (INIS)

    Bakken, J.A.; Denes, P.; Piroue, P.A.; Stickland, D.P.; Sumner, R.L.; Taylor, C.; Barone, L.; Borgia, B.; Diemoz, M.; Dionisi, C.; Falciano, S.; Ferroni, F.; Gratta, G.; Longo, E.; Luminari, L.; Morganti, S.; Valente, E.; Blaising, J.J.; Boutigny, D.; Coignet, G.; Karyotakis, Y.; Sauvage, G.; Schneegans, M.; Vivargent, M.; Extermann, P.; Morand, G.; Ossmann, J.; Ruckstuhl, W.; Schaad, T.P.; Lecoq, P.; Walk, W.; Li, P.J.; Micke, M.; Micke, U.; Schmitz, D.

    1988-01-01

    We report on a precise measurement of the energy loss through ionization by pions in bismuth germanate performed at several values of the incident particles momentum with a prototype of the L3 electromagnetic calorimeter. The experimental results are in good agreement with theoretical predictions showing the relativistic rise modified by density effect. (orig.)

  5. Ionizing radiation from tobacco

    International Nuclear Information System (INIS)

    Westin, J.B.

    1987-01-01

    Accidents at nuclear power facilities seem inevitably to bring in their wake a great deal of concern on the part of both the lay and medical communities. Relatively little attention, however, is given to what may be the largest single worldwide source of effectively carcinogenic ionizing radiation: tobacco. The risk of cancer deaths from the Chernobyl disaster are tobacco smoke is discussed

  6. Ionization beam scanner

    CERN Multimedia

    CERN PhotoLab

    1973-01-01

    Inner structure of an ionization beam scanner, a rather intricate piece of apparatus which permits one to measure the density distribution of the proton beam passing through it. On the outside of the tank wall there is the coil for the longitudinal magnetic field, on the inside, one can see the arrangement of electrodes creating a highly homogeneous transverse electric field.

  7. Basic ionizing radiation symbol

    International Nuclear Information System (INIS)

    1987-01-01

    A description is given of the standard symbol for ionizing radiation and of the conditions under which it should not be used. The Arabic equivalent of some English technical terms in this subject is given in one page. 1 ref., 1 fig

  8. Ionizing radiation and life.

    Science.gov (United States)

    Dartnell, Lewis R

    2011-01-01

    Ionizing radiation is a ubiquitous feature of the Cosmos, from exogenous cosmic rays (CR) to the intrinsic mineral radioactivity of a habitable world, and its influences on the emergence and persistence of life are wide-ranging and profound. Much attention has already been focused on the deleterious effects of ionizing radiation on organisms and the complex molecules of life, but ionizing radiation also performs many crucial functions in the generation of habitable planetary environments and the origins of life. This review surveys the role of CR and mineral radioactivity in star formation, generation of biogenic elements, and the synthesis of organic molecules and driving of prebiotic chemistry. Another major theme is the multiple layers of shielding of planetary surfaces from the flux of cosmic radiation and the various effects on a biosphere of violent but rare astrophysical events such as supernovae and gamma-ray bursts. The influences of CR can also be duplicitous, such as limiting the survival of surface life on Mars while potentially supporting a subsurface biosphere in the ocean of Europa. This review highlights the common thread that ionizing radiation forms between the disparate component disciplines of astrobiology. © Mary Ann Liebert, Inc.

  9. Ionization chamber smoke detectors

    International Nuclear Information System (INIS)

    1988-03-01

    One kind of smoke detector, the ionization-type, is regulated by the Atomic Energy Control Board (AECB) because it uses a radioactive substance in its mechanism. Radioactivity and radiation are natural phenomena, but they are not very familiar to the average householder. This has led to a number of questions being asked of the AECB. These questions and AECB responses are outlined

  10. Multiphoton ionization of H2+ in xuv laser pulses

    International Nuclear Information System (INIS)

    Guan Xiaoxu; Secor, Ethan B.; Bartschat, Klaus; Schneider, Barry I.

    2011-01-01

    We consider the ionization of the hydrogen molecular ion after one-, two-, and three-photon absorption over a large range of photon energies between 9 and 40 eV in the fixed-nuclei approximation. The temporal development of the system is obtained in a fully ab initio time-dependent grid-based approach in prolate spheroidal coordinates. The alignment dependence of the one-photon ionization amplitude is highlighted in the framework of time-dependent perturbation theory. For one-photon ionization as a function of the nuclear separation, the calculations reveal a significant minimum in the ionization probability. The suppressed ionization is attributed to a Cooper-type minimum, which is similar, but not identical, to the cancellation effect observed in photoionization cross sections of some noble-gas atoms. The effect of the nonspherical two-center Coulomb potential is analyzed. For two- and three-photon ionization, the angle-integrated cross sections clearly map out intermediate-state resonances, and the predictions of the current computations agree very well with those from time-independent calculations. The dominant emission modes for two-photon ionization are found to be very similar in both resonance and off-resonance regions.

  11. Practical calculation of amplitudes for electron-impact ionization

    International Nuclear Information System (INIS)

    McCurdy, C. William; Horner, Daniel A.; Rescigno, Thomas N.

    2001-01-01

    An integral expression that is formally valid only for short-range potentials is applied to the problem of calculating the amplitude for electron-impact ionization. It is found that this expression provides a practical and accurate path to the calculation of singly differential cross sections for electron-impact ionization. Calculations are presented for the Temkin-Poet and collinear models for ionization of hydrogen by electron impact. An extension of the finite-element approach using the discrete-variable representation, appropriate for potentials with discontinuous derivatives like the Temkin-Poet interaction, is also presented

  12. The study of multiphoton ionization processes in hydrogen atoms

    International Nuclear Information System (INIS)

    Mohammad, M.A.

    1981-01-01

    In this thesis we investigate theoretically the multiphoton ionization of hydrogen atoms based on perturbation theory.The main problem in the numorical evaluation is the appearance of infinite summation over the matrix element and energy denominators of the intermediate state in the formula for ionization cross section.Our numerical result is in excellent agreement with other workers.In the last part of the thesis we have again calculated the two photon ionization of hydrogen atoms using momentum translation approximation of Reiss.The method in general is in fair agreement with other calculations but dose not show the resonance behaviour.(2 tabs., 1 fig., 45 refs.)

  13. Heating of the solar chromosphere by ionization pumping

    Science.gov (United States)

    Lindsey, C. A.

    1981-01-01

    A new theory is proposed to explain the heating of the solar chromosphere, and possibly the corona, by the dissipation of hydrodynamic compression waves. The basis of the dissipative mechanism, here referred to as ionization pumping, is hysteresis caused by irreversible relaxation of the chromospheric medium to ionization equilibrium following pressure perturbations. In the middle chromosphere, where hydrogen is partially ionized, it is shown that ionization pumping will cause strong dissipation of waves whose periods are 200s or less. This could cause heating of the chromosphere sufficient to compensate for the radiative losses. The mechanism retains a high efficiency for waves of arbitrarily small amplitude and, thus, can be more efficient than shock dissipation for small perturbations in pressure. The formation of shocks therefore is not required for the dissipation of waves whose periods are several minutes or less.

  14. Heating of the solar chromosphere by ionization pumping

    International Nuclear Information System (INIS)

    Lindsey, C.A.

    1981-01-01

    A new theory is proposed to explain the heating of the solar chromosphere, and possibly the corona, by the dissipation of hydrodynamic compression waves. The basis of the disspative mechanism, here referred to as ''ionization pumping,'' is hysteresis caused by irresversible relaxation of the chromospheric medium to ionization equilibrium following pressure perturbations. In the middle chromosphere, where hydrogen is partially ionized, it is shown that ionization pumping will cause strong dissipation of waves whose periods are approx.200 s or less. This could cause heating of the chromosphere sufficient to compensate for the radiative losses. The mechanism retains a high efficiency for waves of arbitrarily small amplitude and, thus, can be more efficient than shock dissipation for small perturbations in pressure. The formation of shocks therefore is not required for the dissipation of waves whose periods are several minutes or less

  15. Ionization of Interstellar Hydrogen

    Science.gov (United States)

    Whang, Y. C.

    1996-09-01

    Interstellar hydrogen can penetrate through the heliopause, enter the heliosphere, and may become ionized by photoionization and by charge exchange with solar wind protons. A fluid model is introduced to study the flow of interstellar hydrogen in the heliosphere. The flow is governed by moment equations obtained from integration of the Boltzmann equation over the velocity space. Under the assumption that the flow is steady axisymmetric and the pressure is isotropic, we develop a method of solution for this fluid model. This model and the method of solution can be used to study the flow of neutral hydrogen with various forms of ionization rate β and boundary conditions for the flow on the upwind side. We study the solution of a special case in which the ionization rate β is inversely proportional to R2 and the interstellar hydrogen flow is uniform at infinity on the upwind side. We solve the moment equations directly for the normalized density NH/NN∞, bulk velocity VH/VN∞, and temperature TH/TN∞ of interstellar hydrogen as functions of r/λ and z/λ, where λ is the ionization scale length. The solution is compared with the kinetic theory solution of Lallement et al. The fluid solution is much less time-consuming than the kinetic theory solutions. Since the ionization rate for production of pickup protons is directly proportional to the local density of neutral hydrogen, the high-resolution solution of interstellar neutral hydrogen obtained here will be used to study the global distribution of pickup protons.

  16. Equipment for handling ionization chamber

    International Nuclear Information System (INIS)

    Altmann, J.

    1988-01-01

    The device consists of an ionization channel with an ionization chamber, of a support ring, axial and radial bearings, a sleeve, a screw gear and an electric motor. The ionization chamber is freely placed on the bottom of the ionization channel. The bottom part of the channel deviates from the vertical axis. The support ring propped against the axial bearing in the sleeve is firmly fixed to the top part of the ionization channel. The sleeve is fixed to the reactor lid. Its bottom part is provided with a recess for the radial bearing which is propped against a screw wheel firmly connected to the ionization channel. In measuring neutron flux, the screw wheel is rotated by the motor, thus rotating the whole ionization channel such that the ionization chamber is displaced into the reactor core.(J.B.). 1 fig

  17. Ionization Efficiency in the Dayside Martian Upper Atmosphere

    Science.gov (United States)

    Cui, J.; Wu, X.-S.; Xu, S.-S.; Wang, X.-D.; Wellbrock, A.; Nordheim, T. A.; Cao, Y.-T.; Wang, W.-R.; Sun, W.-Q.; Wu, S.-Q.; Wei, Y.

    2018-04-01

    Combining the Mars Atmosphere and Volatile Evolution measurements of neutral atmospheric density, solar EUV/X-ray flux, and differential photoelectron intensity made during 240 nominal orbits, we calculate the ionization efficiency, defined as the ratio of the secondary (photoelectron impact) ionization rate to the primary (photon impact) ionization rate, in the dayside Martian upper atmosphere under a range of solar illumination conditions. Both the CO2 and O ionization efficiencies tend to be constant from 160 km up to 250 km, with respective median values of 0.19 ± 0.03 and 0.27 ± 0.04. These values are useful for fast calculation of the ionization rate in the dayside Martian upper atmosphere, without the need to construct photoelectron transport models. No substantial diurnal and solar cycle variations can be identified, except for a marginal trend of reduced ionization efficiency approaching the terminator. These observations are favorably interpreted by a simple scenario with ionization efficiencies, as a first approximation, determined by a comparison between relevant cross sections. Our analysis further reveals a connection between regions with strong crustal magnetic fields and regions with high ionization efficiencies, which are likely indicative of more efficient vertical transport of photoelectrons near magnetic anomalies.

  18. Multiple ionization of noble gases by 2.0 MeV proton impact: comparison with equi-velocity electron impact ionization

    International Nuclear Information System (INIS)

    Melo, W.S.; Santos, A.C.F.; Sant'Anna, M.M.; Sigaud, G.M.; Montenegro, E.C.

    2002-01-01

    Absolute single- and multiple-ionization cross sections of rare gases (He, Ne, Ar, Kr and Xe) have been measured for collisions with 2.0 MeV p + . A comparison is made with equi-velocity electron impact ionization cross sections as well as with the available proton impact data. For the light rare gases the single-ionization cross sections are essentially the same for both proton and electron impacts, but increasing differences appear for the heavier targets. (author). Letter-to-the-editor

  19. One-photon two-electron processes in helium close to the double ionization threshold

    International Nuclear Information System (INIS)

    Bouri, C.

    2007-04-01

    This work presents a study of the 1 P 0 excited states of He that can be reached by absorption of a single photon carrying an energy close to the double ionization threshold (DIT) (79 eV). Above the DIT, these states are the double continuum states; below, they are the double excited states. These two types of states are tightly coupled to the single continuum states with or without excitation of the residual ion He + , owing to their degeneracy in energy. In a one-photon process, these states can only be formed owing to the electronic correlations in the system which must be well described to obtain quantitative good results. Our study is a part of the work which aims at a united description of all these doubly excited, ionized-excited, and double continuum states. We use the Hyperspherical R-Matrix with Semiclassical Outgoing Waves (HRM-SOW) method, initially dedicated to double photoionization studies. We extend it to extract information on the single continuum. This extension allows us to compute cross sections of single photoionization with or without excitation up to n 50 for an excess of 100 meV just above the double ionization threshold. A deep insight into this process is given by a partial waves analysis. The results obtained shed light on the key role of angular and radial correlations. The numerous data we obtain on double and single ionization allow us to establish a continuity relation between these two processes. We show that single ionization with an infinite excitation of the residual ion merges into double photoionization when the excess energy is redistributed between the two electrons. It appears that this relation is valid not only for low but also for high photon energies. Since the HRM-SOW can produce the integrated cross section for double photoionization with high accuracy in the low energy domain, we check the Wannier threshold law. The parameters extracted support strongly this threshold law, and are in good agreement with experimental

  20. Ionization versus indirect effects of ionizing radiation on cellular DNA

    International Nuclear Information System (INIS)

    Cadet, Jean; Ravanat, Jean-Luc; Douki, Thierry

    2012-01-01

    Emphasis has been placed in the last decade on the elucidation of the main degradation pathways of isolated DNA mediated by hydroxyl radical (OH) and one-electron oxidation reactions as the result of indirect and direct effects of ionizing radiation respectively. This has led to the isolation and characterization of about 100 oxidized purine and pyrimidine nucleosides if hydroperoxide precursors and diastereomers are included. However, far less information is available on the mechanisms of radiation-induced degradation of bases in cellular DNA mostly due partly to analytical difficulties. It may be reminded that the measurement of oxidized nucleosides and bases in nuclear DNA is still a challenging issue which until recently has been hampered by the use of inappropriate methods such as the GC-MS that have led to overestimated values of the lesions by factors varying between two and three orders of magnitude. At the present, using the accurate and sensitive HPLC/MS/MS assay, 11 single modified nucleosides and bases were found to be generated in cellular DNA upon exposure to gamma rays and heavy ions. This validates several of the OH-mediated oxidation pathways of thymine, guanine and adenine that were previously inferred from model studies. The concomitant decrease in the yields of oxidized bases with the increase in the LET of heavy ions is accounted for by the preponderance of indirect effects in the damaging action of ionizing radiation on DNA. Further evidence for the major role played by .OH was provided by the results of exposure of cells to high intensity 266 nm laser pulses. Under these conditions 8-oxo-7,8-dihydroguanine is mostly produced by biphotonic ionization of DNA nucleobases and subsequent hole migration to guanine bases. It is likely that some of the oxidized bases that have been isolated as single lesions are in fact involved in clustered damage. Interestingly it was recently shown that a single oxidation hit is capable of generating complex

  1. Subshell resolved L shell ionization of Bi and U induced by 16 - 45 keV electrons

    International Nuclear Information System (INIS)

    Rahangdale, Hitesh; Das, Pradipta K.; Saha, S.; Mitra, D.

    2015-01-01

    Electron induced inner-shell ionization is important for both fundamental and applied research. Ionization of outer atomic energy levels has been studied extensively than for inner levels. Knowledge of inner shell ionization cross sections is important in X-ray and Auger electron spectroscopy and in the fields of astrophysics, plasma physics, surface science and many more. At electron impact energies near the atomic binding energies the distortion of the wave functions from plane wave towards a spherical wave, due to the electrostatic field of the atoms, needs to be considered. The distorted wave Born approximation (DWBA) calculations, taking relativistic effects and exchange interaction into account, is used to estimate the K, L and M-shell ionization cross-section for the atoms. Earlier experiments on electron impact ionization studies focused mainly on K-shell ionization cross-section, while L and M-shell ionization data were hardly reported. A review of the existing L-shell ionization cross-section data shows that, while the X-ray production cross-sections by electron impact were reported quite a few times, the reporting of subshell resolved ionization cross-sections were rarely found near the ionization threshold region. In the present work, we have measured the X ray production cross-sections of different L lines of Bi and U induced by 16-45 keV electrons and converted the obtained values to the subshell specific ionization cross-sections. The experimental data are compared with the theoretical calculations based on the (DWBA) obtained from PENELOPE. To the best of our knowledge, the subshell resolved electron induced ionization cross-sections for the L-shell of Bi and U are reported here for the first time at the energy values near the corresponding ionization threshold. (author)

  2. Current status of antiproton impact ionization of atoms and molecules: theoretical and experimental perspectives

    DEFF Research Database (Denmark)

    Kirchner, Tom; Knudsen, Helge

    2011-01-01

    Experimental and theoretical progress in the field of antiproton-impact-induced ionization of atoms and molecules is reviewed. We describe the techniques used to measure ionization cross sections and give an overview of the experimental results supplemented by tables of all existing data. An atte......Experimental and theoretical progress in the field of antiproton-impact-induced ionization of atoms and molecules is reviewed. We describe the techniques used to measure ionization cross sections and give an overview of the experimental results supplemented by tables of all existing data...

  3. Chemi-ionization in collisions of metastable argon with sodium

    International Nuclear Information System (INIS)

    Neynaber, R.H.; Magnuson, G.D.

    1977-01-01

    Absolute and relative cross sections were obtained for the Penning-ionization (PI) reaction Ar*+Na→Ar+Na + +e and the associative-ionization (AI) reaction Ar*+Na→ArNa + +e. The studies were made by a merging-beams technique for a relative kinetic energy W of the reactants from nominally 0.01 to 10 eV for PI and 0.01 to 0.4 eV for AI. The Ar* represents a composite of Ar(4s 3 P 2 ) and Ar(4s 3 P 0 ). The PI is directed and occurs predominantly when the difference between the relative kinetic energy of the heavy products and the reactants is approximately 0.1 eV. Cross sections for AI are roughly proportional to W -1 . Cross sections for total ionization (AI plus PI) vary as W -1 / 3 for the lower W

  4. Partial tooth gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  5. Epidemiology and ionizing radiations

    International Nuclear Information System (INIS)

    Bourguignon, M.; Masse, R.; Slama, R.; Spira, A.; Timarche, M.; Laurier, D.; Billon, S.; Rogel, A.; Telle Lamberton, M.; Catelinois, O.; Thierry, I.; Grosche, B.; Ron, E.; Vathaire, F. de; Cherie Challine, L.; Donadieu, J.; Pirard, Ph.; Bloch, J.; Setbon, M.

    2004-01-01

    The ionizing radiations have effects on living being. The determinist effects appear since a threshold of absorbed dose of radiation is reached. In return, the stochastic effects of ionizing radiations are these ones whom apparition cannot be described except in terms of probabilities. They are in one hand, cancers and leukemia, on the other hand, lesions of the genome potentially transmissible to the descendants. That is why epidemiology, defined by specialists as the science that studies the frequency and distribution of illness in time and space, the contribution of factors that determine this frequency and this distribution among human populations. This issue gathers and synthesizes the knowledge and examines the difficulties of methodologies. It allows to give its true place to epidemiology. (N.C.)

  6. Gridded ionization chamber

    International Nuclear Information System (INIS)

    Houston, J.M.

    1977-01-01

    An improved ionization chamber type x-ray detector comprises a heavy gas at high pressure disposed between an anode and a cathode. An open grid structure is disposed adjacent the anode and is maintained at a voltsge intermediate between the cathode and anode potentials. The electric field which is produced by positive ions drifting toward the cathode is thus shielded from the anode. Current measuring circuits connected to the anode are, therefore, responsive only to electron current flow within the chamber and the recovery time of the chamber is shortened. The grid structure also serves to shield the anode from electrical currents which might otherwise be induced by mechanical vibrations in the ionization chamber structure

  7. Essays on partial retirement

    NARCIS (Netherlands)

    Kantarci, T.

    2012-01-01

    The five essays in this dissertation address a range of topics in the micro-economic literature on partial retirement. The focus is on the labor market behavior of older age groups. The essays examine the economic and non-economic determinants of partial retirement behavior, the effect of partial

  8. Sensor for ionizable elements

    International Nuclear Information System (INIS)

    Berkey, E.; Reed, W.A. III; Hickam, W.M.

    1977-01-01

    Sensor to detect thermally ionizable elements or molucules in air, water vapour or oxygen or to be used as alkali leak detector in vacuum systems, e.g. in the pipe system of a liquid-metal cooled FBR. The sensor consists of an filament made of thorium-containing iridium as cathode with a temperature upto 1000 0 C and an anode sheet of molybdenum, nickel or stainless steal. (ORU) [de

  9. Gridded Ionization Chamber

    International Nuclear Information System (INIS)

    Manero Amoros, F.

    1962-01-01

    In the present paper the working principles of a gridded ionization chamber are given, and all the different factors that determine its resolution power are analyzed in detail. One of these devices, built in the Physics Division of the JEN and designed specially for use in measurements of alpha spectroscopy, is described. finally the main applications, in which the chamber can be used, are shown. (Author) 17 refs

  10. K-shell ionization and double-ionization of Au atoms with 1.33 MeV photons

    International Nuclear Information System (INIS)

    Belkacem, A.; Dauvergne, D.; Feinberg, B.; Ionescu, D.; Maddi, J.; Sorensen, A.H.

    2000-01-01

    At relativistic energies, the cross section for the atomic photoelectric effect drops off as does the cross section for liberating any bound electron through Compton scattering. However, when the photon energy exceeds twice the rest mass of the electron, ionization may proceed via electron-positron pair creation. We used 1.33 MeV photons impinging on Au thin foils to study double K-shell ionization and vacuum-assisted photoionization. The preliminary results yield a ratio of vacuum-assisted photoionization and pair creation of 2x10 -3 , a value that is substantially higher than the ratio of photo double ionization to single photoionization that is found to be 0.5-1x10 -4 . Because of the difficulties and large error bars associated with the small cross sections additional measurements are needed to minimize systematic errors

  11. Pregnancy and ionizing radiation

    International Nuclear Information System (INIS)

    Plataniotis, Th.N.; Nikolaou, K.I.; Syrgiamiotis, G.V.; Dousi, M.; Panou, Th.; Georgiadis, K.; Bougias, C.

    2008-01-01

    Full text: In this report there will be presented the effects of ionizing radiation at the fetus and the necessary radioprotection. The biological results on the fetus, caused by the irradiation, depend on the dose of ionizing radiation that it receives and the phase of its evolution. The imminent effects of the irradiation can cause the fetus death, abnormalities and mental retardation, which are the result of overdose. The effects are carcinogenesis and leukemia, which are relative to the acceptable irradiating dose at the fetus and accounts about 0,015 % per 1 mSv. The effects of ionizing radiation depend on the phase of the fetus evolution: 1 st phase (1 st - 2 nd week): presence of low danger; 2 nd phase (3 rd - 8 th week): for doses >100 mSv there is the possibility of dysplasia; 3 rd phase (8 th week - birth): this phase concerns the results with a percentage 0,015 % per 1 mSv. We always must follow some rules of radioprotection and especially at Classical radiation use of necessary protocols (low dose), at Nuclear Medicine use of the right radioisotope and the relative field of irradiation for the protection of the adjacent healthy tissues and at Radiotherapy extreme caution is required regarding the dose and the treatment. In any case, it is forbidden to end a pregnancy when the pregnant undergoes medical exams, in which the uterus is in the beam of irradiation. The radiographer must always discuss the possibility of pregnancy. (author)

  12. Non-ionizing radiation

    International Nuclear Information System (INIS)

    Fischer, P.G.

    1983-01-01

    The still growing use of non-ionizing radiation such as ultraviolet radiation laser light, ultrasound and infrasound, has induced growing interest in the effects of these types of radiation on the human organism, and in probable hazards emanating from their application. As there are up to now no generally approved regulations or standards governing the use of non-ionizing radiation and the prevention of damage, it is up to the manufacturers of the relevant equipment to provide for safety in the use of their apparatus. This situation has led to a feeling of incertainty among manufacturers, as to how which kind of damage should be avoided. Practice has shown that there is a demand for guidelines stating limiting values, for measuring techniques clearly indicating safety thresholds, and for safety rules providing for safe handling. The task group 'Non-ionizing radiation' of the Radiation Protection Association started a programme to fulfill this task. Experts interested in this work have been invited to exchange their knowledge and experience in this field, and a collection of loose leaves will soon be published giving information and recommendations. (orig./HP) [de

  13. Two-center interference effects in (e, 2e) ionization of H2 and CO2 at large momentum transfer

    Science.gov (United States)

    Yamazaki, Masakazu; Nakajima, Isao; Satoh, Hironori; Watanabe, Noboru; Jones, Darryl; Takahashi, Masahiko

    2015-09-01

    In recent years, there has been considerable interest in understanding quantum mechanical interference effects in molecular ionization. Since this interference appears as a consequence of coherent electron emission from the different molecular centers, it should depend strongly on the nature of the ionized molecular orbital. Such molecular orbital patterns can be investigated by means of binary (e, 2e) spectroscopy, which is a kinematically-complete electron-impact ionization experiment performed under the high-energy Bethe ridge conditions. In this study, two-center interference effects in the (e, 2e) cross sections of H2 and CO2 at large momentum transfer are demonstrated with a high-statistics experiment, in order to elucidate the relationship between molecular orbital patterns and the interference structure. It is shown that the two-center interference is highly sensitive to the phase, spatial pattern, symmetry of constituent atomic orbital, and chemical bonding nature of the molecular orbital. This work was partially supported by Grant-in-Aids for Scientific Research (S) (No. 20225001) and for Young Scientists (B) (No. 21750005) from the Ministry of Education, Culture, Sports, Science and Technology.

  14. Partial Actions, Paradoxicality and Topological full Groups

    DEFF Research Database (Denmark)

    Scarparo, Eduardo

    uniform Roe algebra is finite. In Article C, we analyze the C*-algebra generated by the Koopman representation of a topological full group, showing, in particular, that it is not AF andhas real rank zero. We also prove that if G is a finitely generated, elementary amenable group, and C*(G) has real rank......We study how paradoxicality properties affect the way groups partially acton topological spaces and C*-algebras. We also investigate the real rank zero and AF properties for certain classes of group C*-algebras. Specifically, in article A, we characterize supramenable groups in terms of existence...... of invariant probability measures for partial actions on compact Hausdorff spaces and existence of tracial states on partial crossed products. These characterizations show that, in general, one cannot decompose a partial crossed product of a C*-algebra by a semidirect product of groups as two iterated...

  15. Theory of electron-impact ionization of atoms

    International Nuclear Information System (INIS)

    Kadyrov, A.S.; Stelbovics, A.T.; Bray, I.; Mukhamedzhanov, A.M.

    2004-01-01

    The existing formulations of electron-impact ionization of a hydrogenic target suffer from a number of formal problems including an ambiguous and phase-divergent definition of the ionization amplitude. An alternative formulation of the theory is given. An integral representation for the ionization amplitude which is free of ambiguity and divergence problems is derived and is shown to have four alternative, but equivalent, forms well suited for practical calculations. The extension to amplitudes of all possible scattering processes taking place in an arbitrary three-body system follows. A well-defined conventional post form of the breakup amplitude valid for arbitrary potentials including the long-range Coulomb interaction is given. Practical approaches are based on partial-wave expansions, so the formulation is also recast in terms of partial waves and partial-wave expansions of the asymptotic wave functions are presented. In particular, expansions of the asymptotic forms of the total scattering wave function, developed from both the initial and the final state, for electron-impact ionization of hydrogen are given. Finally, the utility of the present formulation is demonstrated on some well-known model problems

  16. Recurrent Partial Words

    Directory of Open Access Journals (Sweden)

    Francine Blanchet-Sadri

    2011-08-01

    Full Text Available Partial words are sequences over a finite alphabet that may contain wildcard symbols, called holes, which match or are compatible with all letters; partial words without holes are said to be full words (or simply words. Given an infinite partial word w, the number of distinct full words over the alphabet that are compatible with factors of w of length n, called subwords of w, refers to a measure of complexity of infinite partial words so-called subword complexity. This measure is of particular interest because we can construct partial words with subword complexities not achievable by full words. In this paper, we consider the notion of recurrence over infinite partial words, that is, we study whether all of the finite subwords of a given infinite partial word appear infinitely often, and we establish connections between subword complexity and recurrence in this more general framework.

  17. Detoxification of snake venom using ionizing radiation

    International Nuclear Information System (INIS)

    Rogero, J.R.; Nascimento, N.

    1995-01-01

    It is generally recognized that energy absorbed by ionizing radiation (gamma rays) can inactivate biological material in tow ways. A direct effects occurs when the primary event, i.e., ionization, is produced in the molecule itself. This is the case when a compound is irradiated in dry state. When a compound is irradiated in a solution, the indirect effect joins the direct. Since water is the most abundant constituent of biological material, it is important to consider the species produced by excitation and ionization of water itself, and the reaction of these species with the target molecules of biological importance. This indirect effect results from the reactions among the studied molecules and the products of radiation interaction with water or other solvents. Highly reactive compounds, the so-called free radicals, which are formed many reactions among themselves, with the dissolved gas, and with other molecules in the solution. With water, the excitation is less important than ionization which is followed within picosecond by the formation of free hydroxyl radicals and hydrated electrons. Alexander and Hamilton showed that irradiation of proteins has revealed damage to aminoacid side chains, production of new groups, splitting of peptide bonds and formation of intramolecular and intermolecular cross-links. With these results it would be possible to use ionizing radiation to change those proteins molecules in order to improve some of their properties according to the necessity. On the other hand, it is recognized that venoms in general are poorly immunogenic, yet fairly toxic. This cause problems because serotherapy is the treatment of choice in snakebite envenomations, and horse antivenom availability is dependent upon. (author)

  18. Ionization photophysics and spectroscopy of cyanoacetylene

    International Nuclear Information System (INIS)

    Leach, Sydney; Champion, Norbert; Garcia, Gustavo A.; Fray, Nicolas; Gaie-Levrel, François; Mahjoub, Ahmed; Bénilan, Yves; Gazeau, Marie-Claire; Schwell, Martin

    2014-01-01

    Photoionization of cyanoacetylene was studied using synchrotron radiation over the non-dissociative ionization excitation range 11–15.6 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of cyanoacetylene was measured as 11.573 ± 0.010 eV. A detailed analysis of photoelectron spectra of HC 3 N involves new aspects and new assignments of the vibrational components to excitation of the A 2 Σ + and B 2 Π states of the cation. Some of the structured autoionization features observed in the 11.94 to 15.5 eV region of the total ion yield (TIY) spectrum were assigned to two Rydberg series converging to the B 2 Π state of HC 3 N + . A number of the measured TIY features are suggested to be vibrational components of Rydberg series converging to the C 2 Σ + state of HC 3 N + at ≈17.6 eV and others to valence shell transitions of cyanoacetylene in the 11.6–15 eV region. The results of quantum chemical calculations of the cation electronic state geometries, vibrational frequencies and energies, as well as of the C–H dissociation potential energy profiles of the ground and electronic excited states of the ion, are compared with experimental observations. Ionization quantum yields are evaluated and discussed and the problem of adequate calibration of photoionization cross-sections is raised

  19. Ionization photophysics and spectroscopy of cyanoacetylene

    Energy Technology Data Exchange (ETDEWEB)

    Leach, Sydney; Champion, Norbert [LERMA UMR CNRS 8112, Observatoire de Paris-Meudon, 5 place Jules-Jansen, 92195 Meudon (France); Garcia, Gustavo A.; Fray, Nicolas; Gaie-Levrel, François [Synchrotron SOLEIL, L’Orme des Merisiers, St. Aubin, B.P. 48, 91192, Gif-sur-Yvette Cedex (France); Mahjoub, Ahmed; Bénilan, Yves; Gazeau, Marie-Claire; Schwell, Martin [LISA UMR CNRS 7583, Université Paris Est Créteil and Université Paris Diderot, Institut Pierre Simon Laplace, 61 Avenue du Général de Gaulle, 94010 Créteil (France)

    2014-05-07

    Photoionization of cyanoacetylene was studied using synchrotron radiation over the non-dissociative ionization excitation range 11–15.6 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of cyanoacetylene was measured as 11.573 ± 0.010 eV. A detailed analysis of photoelectron spectra of HC{sub 3}N involves new aspects and new assignments of the vibrational components to excitation of the A{sup 2}Σ{sup +} and B{sup 2}Π states of the cation. Some of the structured autoionization features observed in the 11.94 to 15.5 eV region of the total ion yield (TIY) spectrum were assigned to two Rydberg series converging to the B{sup 2}Π state of HC{sub 3}N{sup +}. A number of the measured TIY features are suggested to be vibrational components of Rydberg series converging to the C{sup 2}Σ{sup +} state of HC{sub 3}N{sup +} at ≈17.6 eV and others to valence shell transitions of cyanoacetylene in the 11.6–15 eV region. The results of quantum chemical calculations of the cation electronic state geometries, vibrational frequencies and energies, as well as of the C–H dissociation potential energy profiles of the ground and electronic excited states of the ion, are compared with experimental observations. Ionization quantum yields are evaluated and discussed and the problem of adequate calibration of photoionization cross-sections is raised.

  20. Optical observations on critical ionization velocity experiments in space

    International Nuclear Information System (INIS)

    Stenbaek-Nielsen, H.C.

    1993-01-01

    A number of Critical Ionization Velocity (CIV) experiments have been performed in space. CIV has been observed in laboratory experiments, but experiments in space have been inconclusive. Most space experiments have used barium which ionizes easily, and with emission lines from both neutrals and ions in the visible optical observations can be made from the ground. Also other elements, such as xenon, strontium and calcium, have been used. High initial ionization in some barium release experiments has been claimed due to CIV. However, a number of reactions between barium and the ambient plasma have been suggested as more likely processes. Currently the most popular process in this debate is charge exchange with O + . This process has a large cross section, but is it large enough? The cross section for charge exchange with calcium should be even larger, but in a double release of barium and calcium (part of the NASA CRRES release experiments) most ionization was observed from the barium release. Moreover, if charge exchange is the dominant process, the amount of ionization should relate to the oxygen ion density, and that does not appear to be the case. Other processes, such as associative ionization, have also been proposed, but yields are uncertain because the reaction rates are very poorly known

  1. Determination of photoionization cross-sections of different organic molecules using gas chromatography coupled to single-photon ionization (SPI) time-of-flight mass spectrometry (TOF-MS) with an electron-beam-pumped rare gas excimer light source (EBEL): influence of molecular structure and analytical implications.

    Science.gov (United States)

    Eschner, Markus S; Zimmermann, Ralf

    2011-07-01

    This work describes a fast and reliable method for determination of photoionization cross-sections (PICS) by means of gas chromatography (GC) coupled to single-photon ionization mass spectrometry (SPI-MS). Photoionization efficiency (PIE) data for 69 substances was obtained at a photon energy of 9.8 ± 0.4 eV using an innovative electron-beam-pumped rare gas excimer light source (EBEL) filled with argon. The investigated analytes comprise 12 alkylbenzenes as well as 11 other substituted benzenes, 23 n-alkanes, ten polyaromatic hydrocarbons, seven aromatic heterocycles, and six polyaromatic heterocycles. Absolute PICS for each substance at 9.8 eV are calculated from the relative photoionization efficiencies of the compounds with respect to benzene, whose photoionization cross-section data is well known. Furthermore, a direct correlation between the type of benzene substituents and their absolute PICS is presented and discussed in depth. Finally, comparison of previously measured photoionization cross-sections for 20 substances shows good agreement with the data of the present work.

  2. Quantum-mechanical study of ionization in slow collisions of antiprotons with hydrogen atoms

    International Nuclear Information System (INIS)

    Sakimoto, Kazuhiro

    2004-01-01

    The cross sections for the ionization p+H→p+p+e at low collision energies are computed with a complete quantum-mechanical method of time-dependent wave-packet propagation, which was applied to the protonium formation (→pp+e) by the present author [Phys. Rev. A 65, 012706 (2002)]. The ionization process shows very large cross sections even near threshold energy. An impact-parameter semiclassical method, in which the trajectory bending is taken into account by the introduction of the adiabatic potential, is also examined for the calculation of the ionization cross section. The semiclassical results are in good agreement with the quantum-mechanical results

  3. Impact parameter dependence of inner-shell ionization probabilities

    International Nuclear Information System (INIS)

    Cocke, C.L.

    1974-01-01

    The probability for ionization of an inner shell of a target atom by a heavy charged projectile is a sensitive function of the impact parameter characterizing the collision. This probability can be measured experimentally by detecting the x-ray resulting from radiative filling of the inner shell in coincidence with the projectile scattered at a determined angle, and by using the scattering angle to deduce the impact parameter. It is conjectured that the functional dependence of the ionization probability may be a more sensitive probe of the ionization mechanism than is a total cross section measurement. Experimental results for the K-shell ionization of both solid and gas targets by oxygen, carbon and fluorine projectiles in the MeV/amu energy range will be presented, and their use in illuminating the inelastic collision process discussed

  4. THE ESCAPE FRACTION OF IONIZING RADIATION FROM GALAXIES

    International Nuclear Information System (INIS)

    Benson, Andrew; Venkatesan, Aparna; Shull, J. Michael

    2013-01-01

    The escape of ionizing radiation from galaxies plays a critical role in the evolution of gas in galaxies, and the heating and ionization history of the intergalactic medium. We present semi-analytic calculations of the escape fraction of ionizing radiation for both hydrogen and helium from galaxies ranging from primordial systems to disk-type galaxies that are not heavily dust-obscured. We consider variations in the galaxy density profile, source type, location, and spectrum, and gas overdensity/distribution factors. For sufficiently hard first-light sources, the helium ionization fronts closely track or advance beyond that of hydrogen. Key new results in this work include calculations of the escape fractions for He I and He II ionizing radiation, and the impact of partial ionization from X-rays from early active galactic nuclei or stellar clusters on the escape fractions from galaxy halos. When factoring in frequency-dependent effects, we find that X-rays play an important role in boosting the escape fractions for both hydrogen and helium, but especially for He II. We briefly discuss the implications of these results for recent observations of the He II reionization epoch at low redshifts, as well as the UV data and emission-line signatures from early galaxies anticipated from future satellite missions.

  5. THE ESCAPE FRACTION OF IONIZING RADIATION FROM GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Benson, Andrew [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Venkatesan, Aparna [Department of Physics and Astronomy, University of San Francisco, San Francisco, CA 94117 (United States); Shull, J. Michael, E-mail: abenson@obs.carnegiescience.edu, E-mail: avenkatesan@usfca.edu, E-mail: michael.shull@colorado.edu [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States)

    2013-06-10

    The escape of ionizing radiation from galaxies plays a critical role in the evolution of gas in galaxies, and the heating and ionization history of the intergalactic medium. We present semi-analytic calculations of the escape fraction of ionizing radiation for both hydrogen and helium from galaxies ranging from primordial systems to disk-type galaxies that are not heavily dust-obscured. We consider variations in the galaxy density profile, source type, location, and spectrum, and gas overdensity/distribution factors. For sufficiently hard first-light sources, the helium ionization fronts closely track or advance beyond that of hydrogen. Key new results in this work include calculations of the escape fractions for He I and He II ionizing radiation, and the impact of partial ionization from X-rays from early active galactic nuclei or stellar clusters on the escape fractions from galaxy halos. When factoring in frequency-dependent effects, we find that X-rays play an important role in boosting the escape fractions for both hydrogen and helium, but especially for He II. We briefly discuss the implications of these results for recent observations of the He II reionization epoch at low redshifts, as well as the UV data and emission-line signatures from early galaxies anticipated from future satellite missions.

  6. Resonant-enhanced above-threshold ionization of atoms by XUV short laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, V.D. [Departamento de Fisica, FCEyN, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina)], E-mail: vladimir@df.uba.ar; Macri, P.A. [Instituto de Investigaciones Fisicas de Mar del Plata (IFIMAR), Departamento de Fisica, FCEyN, Universidad Nacional de Mar del Plata, CONICET, Funes 3350, 7600 Mar del Plata (Argentina); Arbo, D.G. [Instituto de Astronomia y Fisica del Espacio, UBA-CONICET, CC 67 Suc 28 Buenos Aires (Argentina)

    2009-01-15

    Above-threshold ionization of atoms by XUV short laser pulses is investigated close to the resonant 1s-2p transitions. Both ab initio TDSE and a theoretical Coulomb-Volkov like theory are used to study the enhancement in the ionization probabilities. Our modified Coulomb-Volkov theory, fully accounting for the important 1s-2p transition is able to explain the spectrum as well as the total ionization cross sections.

  7. Ionization detectors, ch. 3

    International Nuclear Information System (INIS)

    Sevcik, J.

    1976-01-01

    Most measuring devices used in gas chromatography consist of detectors that measure the ionization current. The process is based on the collision of a moving high-energy particle with a target particle that is ionised while an electron is freed. The discussion of the conditions of the collision reaction, the properties of the colliding particles, and the intensity of the applied field point to a unified classification of ionisation detectors. Radioactive sources suitable for use in these detectors are surveyed. The slow-down mechanism, recombination and background current effect are discussed

  8. Multiple chamber ionization detector

    International Nuclear Information System (INIS)

    Solomon, E.E.

    1982-01-01

    An ionization smoke detector employs a single radiation source in a construction comprising at least two chambers with a center or node electrode. The radioactive source is associated with this central electrode, and its positioning may be adjusted relative to the electrode to alter the proportion of the source that protrudes into each chamber. The source may also be mounted in the plane of the central electrode, and positioned relative to the center of the electrode. The central electrode or source may be made tiltable relative to the body of the detector

  9. Personnel ionizing radiation dosimeter

    International Nuclear Information System (INIS)

    Williams, R.A.

    1975-01-01

    A dosimeter and method for use by personnel working in an area of mixed ionizing radiation fields for measuring and/or determining the effective energy of x- and gamma radiation; beta, x-, and gamma radiation dose equivalent to the surface of the body; beta, x-, and gamma radiation dose equivalent at a depth in the body; the presence of slow neutron, fast neutron dose equivalent; and orientation of the person wearing the dosimeter to the source of radiation is disclosed. Optionally integrated into this device and method are improved means for determining neutron energy spectrum and absorbed dose from fission gamma and neutron radiation resulting from accidental criticality

  10. Doubly resonant multiphoton ionization

    International Nuclear Information System (INIS)

    Crance, M.

    1978-01-01

    A particular case of doubly resonant multiphoton ionization is theoretically investigated. More precisely, two levels quasi-resonant with two successive harmonics of the field frequency are considered. The method used is based on the effective operator formalism first introduced for this problem by Armstrong, Beers and Feneuille. The main result is to show the possibility of observing large interference effects on the width of the resonances. Moreover this treatment allows us to make more precise the connection between effective operator formalism and standard perturbation theory

  11. Plasma production via field ionization

    Directory of Open Access Journals (Sweden)

    C. L. O’Connell

    2006-10-01

    Full Text Available Plasma production via field ionization occurs when an incoming particle beam is sufficiently dense that the electric field associated with the beam ionizes a neutral vapor or gas. Experiments conducted at the Stanford Linear Accelerator Center explore the threshold conditions necessary to induce field ionization by an electron beam in a neutral lithium vapor. By independently varying the transverse beam size, number of electrons per bunch, or bunch length, the radial component of the electric field is controlled to be above or below the threshold for field ionization. Additional experiments ionized neutral xenon and neutral nitric oxide by varying the incoming beam’s bunch length. A self-ionized plasma is an essential step for the viability of plasma-based accelerators for future high-energy experiments.

  12. Ionization of H2O molecules through second order collisions in an argon-filled flow ionization chamber

    International Nuclear Information System (INIS)

    Leonhardt, J.

    1976-01-01

    In an argon-filled ionization chamber with a constant radionuclide radiation source, the ionization of H 2 O through second order collisions with 3sub(p) 2 states of argon excited by field-accelerated electrons is considered within the range of discharge caused by external potentials under atmospheric pressure. It is found that the logarithm of the change of ionization current is proportional to power 3/2 of the electric field strength. Possible formation mechanisms are discussed. Most probable is the ionization of H 2 O through collision with Ar 2 argon dimers originating from excited metastable atoms as a result of triple collision. The production cross section for H 2 O + has been estimated to be sigmasub(H 2 O) approximately 5x10 -15 . (author)

  13. Biology of ionizing radiation effects

    International Nuclear Information System (INIS)

    Ferradini, C.; Pucheault, J.

    1983-01-01

    The present trends in biology of ionizing radiation are reviewed. The following topics are investigated: interaction of ionizing radiations with matter; the radiolysis of water and aqueous solutions; properties of the free radicals intervening in the couples O 2 /H 2 O and H 2 O/H 2 ; radiation chemistry of biological compounds; biological effects of ionizing radiations; biochemical mechanisms involving free radicals as intermediates; applications (biotechnological applications, origins of life) [fr

  14. News about ionized food identification

    International Nuclear Information System (INIS)

    Raffi, J.

    1995-01-01

    The ionizing radiations are used to clean food and increase their preservation life. If a lot of countries permits ionized products commercialization, others are opposed to it. To control the commercial exchanges, check the applied treatment aim and give to the consumers a better information, several ionized food identification methods were perfected and several are about to be recognized as european standards. 4 refs. 3 figs, 1 tab

  15. Resonance ionization spectroscopy 1990

    International Nuclear Information System (INIS)

    Parks, J.E.; Omenetto, N.

    1991-01-01

    The Fifth International Symposium on Resonance Ionization Spectroscopy (RIS) and its Applications was held in Varese, Italy, 16-21 September 1990. Interest in RIS and its applications continues to grow, and RIS is expanding into a more diverse and mature field of study. This maturity was evident in this meeting both in the basic science and understanding of RIS processes and in the number of new and improved applications and techniques. The application of RIS techniques to molecular detection problems made remarkable progress since the last meeting two years ago. Subtle effects pertaining to isotopic discrimination received more theoretical attention, and there now seems to be good understanding of these effects, which can lead to correction procedures and/or methods to avoid isotopic effects. RIS applications were presented in which significant, real world problems were addressed, demonstrating its capability to solve problems that previously could not be accurately solved by other more traditional techniques. The contributions to the conference are grouped under the following major topic headings: physics applications of rare atoms; laser ionization mechanisms - spectroscopy; atomic, molecular and ion sources; molecular RIS; atomic RIS - Rydberg states; environmental trace analysis; biological and medical applications; state selected chemistry; new laser sources and techniques; ultra-high resolution and isotopic selectivity; surface and bulk analysis. (Author)

  16. Hygiene of ionizing radiations

    International Nuclear Information System (INIS)

    Legare, I.-M.; Conceicao Cunha, M. da

    1976-01-01

    The concepts of quality factor and rem are introduced and a table of biological effects of external ionizing radiation sources is presented. Natural exposures, with tables of background radiation sources and of doses due to cosmic rays on high altitude areas and their populations are treated, as well as medical exposures; artificial background; fallout; scientific, industrial and other sources. The maximum and limit doses for man are given and tables of maximum admissible doses of ionizing radiations for 16-18 year old workers professionaly exposed, for professionals eventually subjected to radiation in their work and for people eventually exposed. Professional protection is discussed and tables are given of half-value layer of water, concrete, iron and lead for radiations of different energies, as well as the classification of exposure zones to the radiations and of maximum acceptable contamination for surfaces. The basic safety standards for radiation protection are summarized; tables are given also with emergency references for internal irradiation. Procedures with patients which received radioisotopes are discussed. At last, consideration is given to the problem of radioactive wastes in connection with the medical use of radionuclides [pt

  17. Foundations of ionizing radiation dosimetry

    International Nuclear Information System (INIS)

    Denisenko, O.N.; Pereslegin, I.A.

    1985-01-01

    Foundations of dosimetry in application to radiotherapy are presented. General characteristics of ionizing radiations and main characteristics of ionizing radiation sources, mostly used in radiotherapy, are given. Values and units for measuring ionizing radiation (activity of a radioactive substance, absorbed dose, exposure dose, integral dose and dose equivalent are considered. Different methods and instruments for ionizing radiation dosimetry are discussed. The attention is paid to the foundations of clinical dosimetry (representation of anatomo-topographic information, choice of radiation conditions, realization of radiation methods, corrections for a configuration and inhomogeneity of a patient's body, account of biological factors of radiation effects, instruments of dose field formation, control of irradiation procedure chosen)

  18. Threshold Law For Positron Impact Ionization of Atoms

    International Nuclear Information System (INIS)

    Ihra, W.; Mota-Furtado, F.; OMahony, P.F.; Macek, J.H.; Macek, J.H.

    1997-01-01

    We demonstrate that recent experiments for positron impact ionization of He and H 2 can be interpreted by extending Wannier theory to higher energies. Anharmonicities in the expansion of the three-particle potential around the Wannier configuration give rise to corrections in the threshold behavior of the breakup cross section. These corrections are taken into account perturbatively by employing the hidden crossing theory. The resulting threshold law is σ(E)∝E 2.640 exp[ -0.73√(E)] . The actual energy range for which the Wannier law is valid is found to be smaller for positron impact ionization than for electron impact ionization. copyright 1997 The American Physical Society

  19. The critical ionization velocity mechnism for the case of gas mixture

    International Nuclear Information System (INIS)

    Raadu, M.A.

    1982-08-01

    The theory of the critical ionization velocity mechnisms is discussed. In the case of gas mixture the critical velocity is expected to depend on the ionization cross sections. An analytic approximation is introduced which can be used to set limits on a generalized expression for the critical velocity of gas mixtures. (Author)

  20. Single Photon Double Ionization of Atomic Oxygen

    Science.gov (United States)

    Wickramarathna, Madhushani; Gorczyca, Thomas; Ballance, Connor; Stolte, Wayne

    2017-04-01

    Single photon double ionization cross sections are calculated using an R-matrix with pseudostates (RMPS) method which was recently applied by Gorczyca et al. for the double photoionization of helium. With the convergence of these theoretical calculations for the simple case of helium, we extend this methodology to consider the more complex case of oxygen double photoionization. We compare our calculated results with recent measurements at the Advanced Light Source, as well as earlier experimental measurements. Our RMPS results agree well, qualitatively, with the experimental measurements, but there exist outstanding discrepancies to be addressed. This project is supported by NASA APRA award NNX17AD41G.

  1. Electron-Impact Excitation Cross Sections for Modeling Non-Equilibrium Gas

    Science.gov (United States)

    Huo, Winifred M.; Liu, Yen; Panesi, Marco; Munafo, Alessandro; Wray, Alan; Carbon, Duane F.

    2015-01-01

    In order to provide a database for modeling hypersonic entry in a partially ionized gas under non-equilibrium, the electron-impact excitation cross sections of atoms have been calculated using perturbation theory. The energy levels covered in the calculation are retrieved from the level list in the HyperRad code. The downstream flow-field is determined by solving a set of continuity equations for each component. The individual structure of each energy level is included. These equations are then complemented by the Euler system of equations. Finally, the radiation field is modeled by solving the radiative transfer equation.

  2. Single and multiple ionization of noble gas atoms by H0 impact

    International Nuclear Information System (INIS)

    Sarkadi, L.; Gulyas, L.; Herczku, P.; Kovacs, S.T.S.; Koever, A.

    2012-01-01

    Complete text of publication follows. The understanding of the mechanisms of collisions between energetic charged particles and neutral atoms is of fundamental significance, and it has large importance in many research fields (plasma physics, astrophysics, materials science, etc.), as well as in number of practical applications. In the present work we measured total direct ionization and electron loss cross sections for the collisions of H 0 atoms with noble gas atoms (He, Ne, Ar, Kr) in the energy range 75-300 keV. The experiment was carried out at the 1.5 MV Van de Graaff accelerator of Atomki by coincident detection of the recoil target ions and the charge-state analyzed scattered projectiles. With this study we wished to obtain information about the role played by the electron of the H 0 projectile in the process of the single and multiple vacancy production induced by the collision. For this purpose we repeated the measurements also with proton projectile under the same experimental conditions. For calibration of the measuring system and normalization of our data we used the cross section values of Ref. [1]. The experimental results were analysed with using the classical trajectory Monte Carlo (CTMC) method. CTMC describes well the experimental data for both projectiles for the single vacancy creation, however we observed increasing deviation between the theory and experiment with increasing number of the created vacancies, as well as with decreasing atomic number of the target atoms. Fig. 1 shows our results obtained for the single, double and triple ionization (q = 1, 2, 3) of Kr at H 0 impact for the two cases when the outgoing projectile is H 0 (a) and H + (b), i.e., for pure ionization of the target, and ionization of the target with simultaneous electron loss of the projectile. The curves in the figure were obtained by two versions of the three-body CTMC theory: a conventional model (dashed curves); and a model taking partially account of the many

  3. Ionization photophysics and spectroscopy of dicyanoacetylene

    International Nuclear Information System (INIS)

    Leach, Sydney; Champion, Norbert; Schwell, Martin; Bénilan, Yves; Fray, Nicolas; Gazeau, Marie-Claire; Garcia, Gustavo A.; Gaie-Levrel, François; Guillemin, Jean-Claude

    2013-01-01

    Photoionization of dicyanoacetylene was studied using synchrotron radiation over the excitation range 8–25 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and detailed spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of dicyanoacetylene was measured as 11.80 ± 0.01 eV. A detailed analysis of the cation spectroscopy involves new aspects and new assignments of the vibrational components to excitation of the quasi-degenerate A 2 Π g , B 2 Σ g + states as well as the C 2 Σ u + and D 2 Π u states of the cation. Some of the structured autoionization features observed in the 12.4–15 eV region of the total ion yield spectrum were assigned to vibrational components of valence shell transitions and to two previously unknown Rydberg series converging to the D 2 Π u state of C 4 N 2 + . The appearance energies of the fragment ions C 4 N + , C 3 N + , C 4 + , C 2 N + , and C 2 + were measured and their heats of formation were determined and compared with existing literature values. Thermochemical calculations of the appearance potentials of these and other weaker ions were used to infer aspects of dissociative ionization pathways

  4. Kinematics of 3-body in Ionization Collision

    International Nuclear Information System (INIS)

    Della Picca, Renata

    2003-01-01

    In this thesis we study three body problems in the frame of the collision theory. First, we deal with the process of autoionization by ion impact where the line profile of the electron emitted is strongly affected by the post-collision interaction with the Coulomb field of the outgoing projectile.Here we analyze how these effects are modified when the projectile velocity is in the close vicinity of the resonant electron velocity.In this energy range, the analysis of the resonance contribution is hindered by the characteristic 'electron capture to the continuum' divergence in the direct term.Here we present a detailed theoretical study of the interplay between both contributions, based on a generalization of the Final-State Interaction model.Finally we propose a modified parameterization of the autoionization line shape in the vicinity of the ECC cusp.Secondly, we study the direct ionization of an atomic target by the impact of a charge projectile, through analysis of the quintuple differential cross section (QDCS) which gives the most complete information about a ionization collision.Its study, without any approximation on the mass ratios can unveil new, not previously observed, structures.In particular, in this work the ionization of Hydrogen molecules by the impact of positrons and muons was studied and a new structure that has not been identified until now was found. Its main characteristics and a possible explanation are presented

  5. [Ionizing and non-ionizing radiation (comparative risk estimations)].

    Science.gov (United States)

    Grigor'ev, Iu G

    2012-01-01

    The population has widely used mobile communication for already more than 15 years. It is important to note that the use of mobile communication has sharply changed the conditions of daily exposure of the population to EME We expose our brain daily for the first time in the entire civilization. The mobile phone is an open and uncontrollable source of electromagnetic radiation. The comparative risk estimation for the population of ionizing and non-ionizing radiation was carried out taking into account the real conditions of influence. Comparison of risks for the population of ionizing and non-ionizing radiation leads us to a conclusion that EMF RF exposure in conditions of wide use of mobile communication is potentially more harmful than ionizing radiation influence.

  6. Ionization of hydrogen by a relativistic heavy projectile

    International Nuclear Information System (INIS)

    Hofstetter, S.; Hofmann, C.; Soff, G.

    1991-10-01

    Using a relativistic analogue of the classical trajectory Monte-Carlo method we investigate the influence of the magnetic field of a relativistic heavy projectile on the ionization cross section of hydrogen. In particular we focus our attention on the angular and energy distribution of the emitted delta electrons. (orig.)

  7. On the photo-ionization of impurity centres in semiconductors

    International Nuclear Information System (INIS)

    Tomak, M.

    1982-10-01

    The dependence of the photo-ionization cross-section on photon energy is calculated. The impurity potential is assumed to be of the Hulthen potential type and bound state wave function is calculated variationally. The results show that, at least in some cases, the Hulthen potential may describe the impurity better than the hydrogen or delta function potentials. (author)

  8. Electron impact ionization of Ar/sup 8 +/

    Energy Technology Data Exchange (ETDEWEB)

    Defrance, P.; Rachafi, S.; Jureta, J.; Meyer, F.; Chantrenne, S.

    1986-01-01

    Absolute electron impact ionization cross-sections have been measured for the Neon-like Ar/sup 8 +/ in the energy range from below the threshold for the metastable state to 2500 eV. No contribution of metastable states is observed. The results are well reproduced by the Distorted Wave Born Approximation. 12 refs., 1 fig.

  9. Ionization in positron- and positronium- collisions with atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Laricchia, G; Brawley, S; Cooke, D A; Murtagh, D J; Williams, A I [UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Koever, A [permanent address: ATOMKI, Institute for Nuclear Research, Debrecen (Hungary)

    2009-11-15

    Recent progress in the experimental study of positron- and positronium-induced ionization of atoms and molecules is outlined. Investigations include integral and differential cross-sections, as well as formation of positronium in the first excited state. Future prospects are discussed.

  10. The ionization mechanisms in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

    Science.gov (United States)

    Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

    2014-11-01

    A novel, gas-tight API interface for gas chromatography-mass spectrometry was used to study the ionization mechanism in direct and dopant-assisted atmospheric pressure photoionization (APPI) and atmospheric pressure laser ionization (APLI). Eight analytes (ethylbenzene, bromobenzene, naphthalene, anthracene, benzaldehyde, pyridine, quinolone, and acridine) with varying ionization energies (IEs) and proton affinities (PAs), and four common APPI dopants (toluene, acetone, anisole, and chlorobenzene) were chosen. All the studied compounds were ionized by direct APPI, forming mainly molecular ions. Addition of dopants suppressed the signal of the analytes with IEs above the IE of the dopant. For compounds with suitable IEs or Pas, the dopants increased the ionization efficiency as the analytes could be ionized through dopant-mediated gas-phase reactions, such as charge exchange, proton transfer, and other rather unexpected reactions, such as formation of [M + 77](+) in the presence of chlorobenzene. Experiments with deuterated toluene as the dopant verified that in case of proton transfer, the proton originated from the dopant instead of proton-bound solvent clusters, as in conventional open or non-tight APPI sources. In direct APLI using a 266 nm laser, a narrower range of compounds was ionized than in direct APPI, because of exceedingly high IEs or unfavorable two-photon absorption cross-sections. Introduction of dopants in the APLI system changed the ionization mechanism to similar dopant-mediated gas-phase reactions with the dopant as in APPI, which produced mainly ions of the same form as in APPI, and ionized a wider range of analytes than direct APLI.

  11. Use of ionizing radiation in grass breeding. II

    International Nuclear Information System (INIS)

    Svetlik, V.; Indruch, I.; Fojtik, A.; Bajer, K.

    1980-01-01

    Ionizing radiation induced sexuality in this apomictic grass. Sexual strains were isolated and selected individuals were crossed. Polycross and recurrent single cross methods allowed restoring apomixis. The resulting apomictic strains showed excellent traits and transgressed hereditary potentials of parental components. The method is described of breeding and the productivity of individual breeding techniques is discussed. It is shown that the number of strains should be reduced and the most productive strains should be used for the formation of synthetic cultivars. (author)

  12. Collisional ionization of Na by HBr in weak to strong electric fields

    International Nuclear Information System (INIS)

    Safinya, K.A.; Gallagher, T.F.; Sandner, W.; Gounand, F.

    1985-01-01

    We report the effect of static electric fields on the collisional ionization of highly excited sodium atoms by HBr. The binding energy dependence of the collisional ionization cross section is measured at zero field and in static electric fields up to that point at which the atom field ionizes. The applied electric field lowers the ionization threshold of the atom from its zero field value. Therefore an atom near the ionization threshold in an electric field is of smaller size than a free field atom with the same binding energy. Thus measuring the binding energy dependence of the cross section at different values of the electric field allows us to study the effects of the physical size of the atom on the cross section. The effect of the electric field was to lower the measured ionization cross section. However, the binding energy dependence of the cross section remains unchanged at the level of our measurement accuracy. The measured cross sections are larger for larger atoms, exhibit a drop with increasing binding energy characteristic of rotational to electronic excitation transfer, and are of order 10 -12 --10 -11 cm 2 . A simple calculation based on dipole (J→ J-1) excitation transfer from the molecule to the atom predicts, with good agreement, the binding energy dependence of the cross section. The electric field dependence of the data however, is not shown in the theory

  13. Applications of ionizing radiations

    International Nuclear Information System (INIS)

    2014-01-01

    Developments in standard applications and brand new nuclear technologies, with high impact on the future of the agriculture, medicine, industry and the environmental preservation. The Radiation Technology Center (CTR) mission is to apply the radiation and radioisotope technologies in Industry, Health, Agriculture, and Environmental Protection, expanding the scientific knowledge, improving human power resources, transferring technology, generating products and offering services for the Brazilian society. The CTR main R and D activities are in consonance with the IPEN Director Plan (2011-2013) and the Applications of Ionizing Radiation Program, with four subprograms: Irradiation of Food and Agricultural Products; Radiation and Radioisotopes Applications in Industry and Environment; Radioactive Sources and Radiation Applications in Human Health; and Radioactive Facilities and Equipment for the Applications of Nuclear Techniques

  14. Reference ionization chamber

    International Nuclear Information System (INIS)

    Golnik, N.; Zielczynski, M.

    1999-01-01

    The paper presents the design of ionization chamber devoted for the determination of the absolute value of the absorbed dose in tissue-equivalent material. The special attention was paid to ensure that the volume of the active gas cavity was constant and well known. A specific property of the chamber design is that the voltage insulators are 'invisible' from any point of the active volume. Such configuration ensures a very good time stability of the electrical field and defines the active volume. The active volume of the chamber was determined with accuracy of 0.3%. This resulted in accuracy of 0.8% in determination of the absorbed dose in the layer of material adherent to the gas cavity. The chamber was applied for calibration purposes at radiotherapy facility in Joint Institute for Nuclear Research in Dubna (Russia) and in the calibration laboratory of the Institute of Atomic Energy in Swierk. (author)

  15. Applications of ionizing radiations

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2014-07-01

    Developments in standard applications and brand new nuclear technologies, with high impact on the future of the agriculture, medicine, industry and the environmental preservation. The Radiation Technology Center (CTR) mission is to apply the radiation and radioisotope technologies in Industry, Health, Agriculture, and Environmental Protection, expanding the scientific knowledge, improving human power resources, transferring technology, generating products and offering services for the Brazilian society. The CTR main R and D activities are in consonance with the IPEN Director Plan (2011-2013) and the Applications of Ionizing Radiation Program, with four subprograms: Irradiation of Food and Agricultural Products; Radiation and Radioisotopes Applications in Industry and Environment; Radioactive Sources and Radiation Applications in Human Health; and Radioactive Facilities and Equipment for the Applications of Nuclear Techniques.

  16. Ionizing radiation detector

    Science.gov (United States)

    Thacker, Louis H.

    1990-01-01

    An ionizing radiation detector is provided which is based on the principle of analog electronic integration of radiation sensor currents in the sub-pico to nano ampere range between fixed voltage switching thresholds with automatic voltage reversal each time the appropriate threshold is reached. The thresholds are provided by a first NAND gate Schmitt trigger which is coupled with a second NAND gate Schmitt trigger operating in an alternate switching state from the first gate to turn either a visible or audible indicating device on and off in response to the gate switching rate which is indicative of the level of radiation being sensed. The detector can be configured as a small, personal radiation dosimeter which is simple to operate and responsive over a dynamic range of at least 0.01 to 1000 R/hr.

  17. Transport processes in ionized gases

    International Nuclear Information System (INIS)

    Kremer, G.M.

    1997-01-01

    Based on kinetic theory of gases and on the combined of Chapman-Enskog and Grad, the laws of Ohm, Fourier and Navier-Stokes are derived for a non-relativistic fully ionized gas. Moreover, the combined method is applied to the BGK model of the relativistic Boltzmann equation and the Ohm's law is derived for a relativistic fully ionized gas. (author)

  18. Amorphous silicon ionizing particle detectors

    Science.gov (United States)

    Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

    1988-01-01

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

  19. Worldwide exposures to ionizing radiation

    International Nuclear Information System (INIS)

    Bennett, B.G.

    1993-01-01

    All of mankind is exposed to ionizing radiation from natural sources, from human practices that release natural and artificial radionuclides to the environment, and from medical radiation procedures. This paper reviews the assessment in the UNSCEAR 1993 Report of the exposures of human populations worldwide to the various sources of ionizing radiation

  20. Food ionizing treatment

    International Nuclear Information System (INIS)

    Strasser, A.; Raffi, J.; Hasselmann, C.

    1997-01-01

    Treatment of food with ionizing radiation is increasingly being recognized as a means of reducing food-borne illnesses and associated medical and other costs. In addition, the process may contribute to food security by preventing post-harvest losses, thereby making more food available to more people, eventually at lower cost. An ever increasing number of countries has approved the irradiation of a long and growing list of different food items, groups of classes, ranging from spices to grains to fruit and vegetables to meats and poultry and seafood. However, perception by consumers has been controversial and concerns have been expressed, particularly related to the safety of irradiated food. Therefore, the toxicological aspects of irradiated food are addressed in this dossier. It should be recognized that food irradiation is perhaps the most thoroughly investigated food processing technology. According to the World Health Organization 'irradiated food produced in accordance with established Good Manufacturing Practice can be considered safe and nutritionally adequate'. A recent evaluation by a WHO/FAO/IAEA study group (Geneva, Sept. 1997) even came to the conclusion, 'that as long as sensory qualities of food are retained and harmful microorganisms are destroyed, the actual amount of ionizing radiation applied is of secondary consideration'. Thus, also treatment of food with doses greater than the currently recommended upper level of 10 kGy by the Codex Alimentarius Commission will not lead to changes in the composition of the food that, from a toxicological point of view, would have an adverse effect on human health. (author)

  1. Multiphoton ionization processes in strong laser

    International Nuclear Information System (INIS)

    Krstic, P.

    1982-01-01

    Multiphoton ionization of hydrogen in ultrastrong laser fields is studied. The previous calculations of this process yield differing result for the transition rate. We show the relations between them and difficulties with each of them. One difficulty is that the finite spatial and time extent of the laser field has been omitted. It is also found that a laser field, which is sufficiently intense to be labeled ultrastrong, makes the electron move relativistically so that it becomes necessary to use Volkov states to describe the electron in the laser field. The transition rate is obtained, using a CO laser as an example, and it is found that the transition rate rises as the laser intensity rises. This is a consequence of the use of relativistic kinematics and is not true nonrelativistically. We also discuss the multiple peaks observed in the energy spectrum of electrons resulting from multiphoton ionization of atoms by lasers. When the laser intensity is large enough for the ponderomotive force to result in appreciable broading of the peaks we show the shape of the broadened peaks contains useful information. We show that the multiphoton ionization probability as a function of laser intensity can be obtained but that the free-free cross sections, which are in principle also obtainable, are probably not obtainable in practice. Finally, we describe the theory of the absorption of more than minimum numbers of photons needed to ionize an atom by an intense laser. The basic approximation used is that the atom is adiabatically deformed by the laser and an impulsive interaction then results in multiphoton absorption. In our first calculation we allow only one resonant excited state to be included in the adiabatic deformation. In our second we also allow the lowest energy continuum to be included. The two results are then compared

  2. Ionization detection system for aerosols

    International Nuclear Information System (INIS)

    Jacobs, M.E.

    1977-01-01

    This invention relates to an improved smoke-detection system of the ionization-chamber type. In the preferred embodiment, the system utilizes a conventional detector head comprising a measuring ionization chamber, a reference ionization chamber, and a normally non-conductive gas triode for discharging when a threshold concentration of airborne particulates is present in the measuring chamber. The improved system utilizes a measuring ionization chamber which is modified to minimize false alarms and reductions in sensitivity resulting from changes in ambient temperature. In the preferred form of the modification, an annular radiation shield is mounted about the usual radiation source provided to effect ionization in the measuring chamber. The shield is supported by a bimetallic strip which flexes in response to changes in ambient temperature, moving the shield relative to the source so as to vary the radiative area of the source in a manner offsetting temperature-induced variations in the sensitivity of the chamber. 8 claims, 7 figures

  3. Crichton ambiguities with infinitely many partial waves

    International Nuclear Information System (INIS)

    Atkinson, D.; Kok, L.P.; de Roo, M.

    1978-01-01

    We construct families of spinless two-particle unitary cross sections that possess a nontrivial discrete phase-shift ambiguity, with in general an infinite number of nonvanishing partial waves. A numerical investigation reveals that some of the previously known finite Crichton ambiguities are merely special cases of the newly constructed examples

  4. Crichton ambiguities with infinitely many partial waves

    NARCIS (Netherlands)

    Atkinson, D.; Kok, L.P.; de Roo, M.

    We construct families of spin less two-particle unitary cross sections that possess a nontrivial discrete phase-shift ambiguity, with in general an infinite number of nonvanishing partial waves. A numerical investigation reveals that some of the previously known finite Crichton ambiguities are

  5. (, 3) Differential cross section of He

    Indian Academy of Sciences (India)

    The angular distribution of the five-fold differential cross section for the electron impact double ionization of He (21 ) and He (23 ) has been studied. The kinematical conditions for maxima/minima in the angular distribution for the two cases have been compared. The two-step process for the double ionization is found to ...

  6. Electron impact ionization of highly charged lithiumlike ions

    International Nuclear Information System (INIS)

    Wong, K.L.

    1992-10-01

    Electron impact ionization cross sections can provide valuable information about the charge-state and power balance of highly charged ions in laboratory and astrophysical plasmas. In the present work, a novel technique based on x-ray measurements has been used to infer the ionization cross section of highly charged lithiumlike ions on the Livermore electron beam ion trap. In particular, a correspondence is established between an observed x ray and an ionization event. The measurements are made at one energy corresponding to approximately 2.3 times the threshold energy for ionization of lithiumlike ions. The technique is applied to the transition metals between Z=22 (titanium, Ti 19+ ) and Z=26 (iron, Fe 23+ ) and to Z=56 (barium, Ba 53+ ). The results for the transition metals, which have an estimated 17-33% uncertainty, are in good overall agreement with a relativistic distorted-wave calculation. However, less good agreement is found for barium, which has a larger uncertainty. Methods for properly accounting for the polarization in the x-ray intensities and for inferring the charge-state abundances from x-ray observations, which were developed for the ionization measurements, as well as an x-ray model that assists in the proper interpretation of the data are also presented

  7. Electron ionization and dissociation of aliphatic amino acids

    Science.gov (United States)

    Papp, P.; Shchukin, P.; Kočíšek, J.; Matejčík, Š.

    2012-09-01

    We present experimental and theoretical study of electron ionization and dissociative ionization to the gas phase amino acids valine, leucine, and isoleucine. A crossed electron/molecular beams technique equipped with quadrupole mass analyzer has been applied to measure mass spectra and ion efficiency curves for formation of particular ions. From experimental data the ionization energies of the molecules and the appearance energies of the fragment ions were determined. Ab initio calculations (Density Functional Theory and G3MP2 methods) were performed in order to calculate the fragmentation paths and interpret the experimental data. The experimental ionization energies of parent molecules [P]+ 8.91 ± 0.05, 8.85 ± 0.05, and 8.79 ± 0.05 eV and G3MP2 ionization energies (adiabatic) of 8.89, 8.88, and 8.81 eV were determined for valine, leucine, and isoleucine, respectively, as well as the experimental and theoretical threshold energies for dissociative ionization channels. The comparison of experimental data with calculations resulted in identification of the ions as well as the neutral fragments formed in the dissociative reactions. Around 15 mass/charge ratio fragments were identified from the mass spectra by comparison of experimental appearance energies with calculated reaction enthalpies for particular dissociative reactions.

  8. Laser-enhanced ionization spectroscopy around the ionization limit

    International Nuclear Information System (INIS)

    Axner, O.; Berglind, T.; Sjoestroem, S.

    1986-01-01

    Laser-induced photoionization and Laser-Enhanced collision Ionization (LEI) of Na, Tl, and Li in flames are detected by measuring the production of charges following a laser excitation. The ionization signal is investigated for excitations of the atoms from lower lying states both to Rydberg states close to the ionization limit, as well as to continuum states, i.e. the process of collision ionization is compared with that of photoionization. The qualitative behaviour of the ionization signal when scanning across the ionization limit is studied. It is shown that the ionization signal has a smooth behaviour when passing from bound states into continuum states. The laser-induced photoionization signal strength of atoms in flames is both calculated and measured and a good agreement is obtained. A calculation of wavelength dependent photoionization signal strengths for a number of elements is also presented. Photoionization is used to determine flame- and geometry-dependent parameters. An implication of photoionization in connection with LEI spectrometry for trace element analysis is that there will be a significant increase in background noise if the sample contains high concentrations of easily photoionizing elements and short wavelength light is used. (orig.)

  9. Hyperbolic partial differential equations

    CERN Document Server

    Witten, Matthew

    1986-01-01

    Hyperbolic Partial Differential Equations III is a refereed journal issue that explores the applications, theory, and/or applied methods related to hyperbolic partial differential equations, or problems arising out of hyperbolic partial differential equations, in any area of research. This journal issue is interested in all types of articles in terms of review, mini-monograph, standard study, or short communication. Some studies presented in this journal include discretization of ideal fluid dynamics in the Eulerian representation; a Riemann problem in gas dynamics with bifurcation; periodic M

  10. Successful removable partial dentures.

    Science.gov (United States)

    Lynch, Christopher D

    2012-03-01

    Removable partial dentures (RPDs) remain a mainstay of prosthodontic care for partially dentate patients. Appropriately designed, they can restore masticatory efficiency, improve aesthetics and speech, and help secure overall oral health. However, challenges remain in providing such treatments, including maintaining adequate plaque control, achieving adequate retention, and facilitating patient tolerance. The aim of this paper is to review the successful provision of RPDs. Removable partial dentures are a successful form of treatment for replacing missing teeth, and can be successfully provided with appropriate design and fabrication concepts in mind.

  11. Beginning partial differential equations

    CERN Document Server

    O'Neil, Peter V

    2011-01-01

    A rigorous, yet accessible, introduction to partial differential equations-updated in a valuable new edition Beginning Partial Differential Equations, Second Edition provides a comprehensive introduction to partial differential equations (PDEs) with a special focus on the significance of characteristics, solutions by Fourier series, integrals and transforms, properties and physical interpretations of solutions, and a transition to the modern function space approach to PDEs. With its breadth of coverage, this new edition continues to present a broad introduction to the field, while also addres

  12. Initial ionization stage of FRC formation

    International Nuclear Information System (INIS)

    Commisso, R.J.; Armstrong, W.T.; Cochrane, J.C.; Ekdahl, C.A.; Lipson, J.; Linford, R.K.; Sherwood, E.G.; Siemon, R.E.; Tuszewski, M.

    1980-01-01

    A Field-Reversed Configuration (FRC) is a prolate compact torus that is confined by poloidal fields only. Theta-pinch formation of an FRC employs an initial bias field, B 1 , whose direction is opposite to that of the main theta-pinch field. Some fraction of the flux associated with this bias field eventually constitutes the closed-field-line flux of the FRC. Experimental and theoretical evidence suggest that the longest-lived FRC's are obtained when the closed flux is maximized. Because the initial ionization is done in the presence of the bias field, the actual bias flux available at the time of application of the main theta-pinch field depends strongly on the initial ionization, or preionization, technique used. In this paper we report on experiments characterizing the previously used theta-pinch preionization technique that employed a net field (bias plus preionization) null, or zero-crossing, of the axial component of the magnetic field to break down the gas. We also discuss results of experiments designed to develop preionization techniques in which the gas breakdown is not accomplished by a zero-crossing

  13. Initial ionization stage of FRC formation

    Energy Technology Data Exchange (ETDEWEB)

    Commisso, R.J.; Armstrong, W.T.; Cochrane, J.C.; Ekdahl, C.A.; Lipson, J.; Linford, R.K.; Sherwood, E.G.; Siemon, R.E.; Tuszewski, M.

    1980-01-01

    A Field-Reversed Configuration (FRC) is a prolate compact torus that is confined by poloidal fields only. Theta-pinch formation of an FRC employs an initial bias field, B/sub 1/, whose direction is opposite to that of the main theta-pinch field. Some fraction of the flux associated with this bias field eventually constitutes the closed-field-line flux of the FRC. Experimental and theoretical evidence suggest that the longest-lived FRC's are obtained when the closed flux is maximized. Because the initial ionization is done in the presence of the bias field, the actual bias flux available at the time of application of the main theta-pinch field depends strongly on the initial ionization, or preionization, technique used. In this paper we report on experiments characterizing the previously used theta-pinch preionization technique that employed a net field (bias plus preionization) null, or zero-crossing, of the axial component of the magnetic field to break down the gas. We also discuss results of experiments designed to develop preionization techniques in which the gas breakdown is not accomplished by a zero-crossing.

  14. The role of multiple ionization and subshell coupling effects in L-shell ionization of Au by oxygen ions

    International Nuclear Information System (INIS)

    Banas, D.; Braziewicz, J.; Pajek, M.; Semaniak, J.; Czyzewski, T.; Fijal, I.; Jaskola, M.; Kretschmer, W.; Mukoyama, T.; Trautmann, D.

    2002-01-01

    The ionization of L-subshell electrons in gold by the impact of 0.4-2.2 MeV amu -1 O ions was studied by observing excited Lγ(L-N, O) x-rays. We demonstrate that both the multiple ionization in outer M- and N-shells as well as the coupling effects in the L-shell play an important role in understanding the measured L-subshell ionization cross sections. The multiple ionization was found to be important in two aspects: first, the analysis of x-ray energy shifts and line broadening was crucial for proper interpretation of measured x-ray spectra; second, the additional vacancies in the M- and N-shells substantially influenced the L 1 -subshell fluorescence and Coster-Kronig (CK) yields, mainly by closing strong L 1 -L 3 M 4,5 CK transitions. The data are compared with the simplified coupled-channels calculations using the 'coupled-subshell model' (CSM) based on the semiclassical approximation (SCA), which describes both direct Coulomb ionization as well as the L-subshell couplings within the same theoretical approach. A good agreement of the present data with the theoretical predictions based on the discussed SCA-CSM approach is observed. Present findings partly explain the long-standing problem of inadequate theoretical description of L-shell ionization by heavy ion impact. (author)

  15. CAREN-4, ENDF/B Utility, Discontinuity Check at Resonance Region Boundary. CHECK-4, ENDF/B Utility, Structure Consistency Check and Format Check. CRECT, ENDF/B Utility, Data Correlation and Data Update. DICT-4, ENDF/B Utility, Section Table of Contents Generator. LISTF-4, ENDF/B Utility, Data Listing. RIGEL-4, ENDF/B Utility, Data Retrieval, BCD to BIN Conversion. SUMUP-4, ENDF/B Utility, Partial Cross-Sections Sum Check Against Tot Cross-Sections

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1975-08-01

    Description of problem or function: These programs are updated versions of ENDF/B checking, retrieval, and display codes capable of processing the Version-IV data files. RIGEL4 retrieves ENDF/B data and changes mode (BCD-BIN) or arrangement. Updated version processes decay data (mf=1, mt=457) and error files. CHECK4 checks the structure, consistency, and formats of ENDF data files. Updated version recognizes newly defined mt and mf numbers, checks mt=457 and the formats of the error files, contains RSIC photon file changes. SUMUP4 checks whether partial cross sections add up to the total. Updated version flags grid points present in the partial cross section, absent in the total. LISTF4 produces interpreted listings of ENDF/B data. Updated version lists mt=457, skips over error files, contains minor corrections. PLOTF4 produces plots of ENDF/B data. Updated version plots mt=457, skips over error files, contains minor corrections. RESEND processes ENDF materials with resonance parameters into a pointwise form. Capability of processing Adler-Adler parameters added. CRECT corrects ENDF/B data files. DICT4 generates a section table of contents (dictionary) for ENDF/B materials. CAREN4 tests for discontinuities across the limits of resonance ranges of an ENDF/B material. Updated version contains minor corrections.

  16. Partial knee replacement - slideshow

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/presentations/100225.htm Partial knee replacement - series—Normal anatomy To use the sharing ... A.M. Editorial team. Related MedlinePlus Health Topics Knee Replacement A.D.A.M., Inc. is accredited ...

  17. Multiple ionization effects in M X-ray emission induced by heavy ions

    International Nuclear Information System (INIS)

    Wang, Xing; Zhao, Yongtao; Cheng, Rui; Zhou, Xianming; Xu, Ge; Sun, Yuanbo; Lei, Yu; Wang, Yuyu; Ren, Jieru; Yu, Yang; Li, Yongfeng; Zhang, Xiaoan; Li, Yaozong; Liang, Changhui; Xiao, Guoqing

    2012-01-01

    M-shell ionization of tungsten by Ar 12+ ions were investigated in the energy range of 1.2–3.0 MeV. The measurements were also implemented for H, He and Xe ions as a comparative study. A significant shift of the M X-ray lines to the higher energy side caused by multiple ionizations, which was verified by the analysis of the intensity ratios of M γ and M αβ , was observed. The total experimental cross sections of tungsten were compared with the PWBA and ECPSSR theoretical predictions, which are based on two extreme assumptions, namely, single ionization and full ionization. -- Highlights: ► Projectiles with low velocity (near Bohr velocity). ► A significant shift of the M X-ray lines to the higher energy side. ► A large enhancement in the M 3 fluorescence yield. ► Theoretical predictions based on single ionization and full ionization.

  18. Beginning partial differential equations

    CERN Document Server

    O'Neil, Peter V

    2014-01-01

    A broad introduction to PDEs with an emphasis on specialized topics and applications occurring in a variety of fields Featuring a thoroughly revised presentation of topics, Beginning Partial Differential Equations, Third Edition provides a challenging, yet accessible,combination of techniques, applications, and introductory theory on the subjectof partial differential equations. The new edition offers nonstandard coverageon material including Burger's equation, the telegraph equation, damped wavemotion, and the use of characteristics to solve nonhomogeneous problems. The Third Edition is or

  19. Dust formation and ionization in novae

    International Nuclear Information System (INIS)

    Yamamoto, Tetsuo; Sato, Shuji; Nariai, Kyoji.

    1979-01-01

    In order to explain the fact that some novae show the increase of infrared radiation indicating the formation of circumstellar dust grains while some others do not, the theory that the formation of dust in the circumstellar envelope of a nova depends on the intensity of ultraviolet radiation from a central star has been presented. It is known that the central star of a nova emits radiation at nearly constant rate, and its effective temperature rises. It was concluded that the novae with higher emission than a certain value are the poor candidates for dust formation because the whole envelope is ionized before dust is formed. But this conclusion is misleading. The evolution of the ultraviolet radiation emanating from a central star is summarized. The condensation of grains is possible when the partial pressure of the vapor, from which the grains are formed, becomes higher than the saturation vapor pressure. The temperature of grains can be estimated by equating the radiations absorbed and emitted. The grains evaporate if the grain temperature is higher than the condensation temperature. The formation of a Stroemgren sphere in the exploding envelope of a nova is discussed. For the formation of grains, it is necessary that temperature drops below the condensation temperature before the whole envelope is ionized. Hence dust grains do not grow if the grain temperature at a phase is higher than the condensation temperature. (Kako, I.)

  20. Determination of first ionization potential of samarium atom using Rydberg series convergence

    International Nuclear Information System (INIS)

    Jayasekharan, T.; Razvi, M.A.N.; Bhale, G.L.

    1999-01-01

    The study of Rydberg states has recently received more attention partially because an efficient isotope selective ionization is possible via these states. In addition, their investigation provides useful information on the atomic structure. An electron in a shell with a high principal quantum number is a sensitive probe for the interaction with the ionic core of the atom. Measurements of these Rydberg levels give valuable data on quantum defects, anomalies in fine structure splitting, polarizabilities, configuration interactions, ionization potentials etc