WorldWideScience

Sample records for neutral atom analyzers

  1. Neutral atom traps.

    Energy Technology Data Exchange (ETDEWEB)

    Pack, Michael Vern

    2008-12-01

    This report describes progress in designing a neutral atom trap capable of trapping sub millikelvin atom in a magnetic trap and shuttling the atoms across the atom chip from a collection area to an optical cavity. The numerical simulation and atom chip design are discussed. Also, discussed are preliminary calculations of quantum noise sources in Kerr nonlinear optics measurements based on electromagnetically induced transparency. These types of measurements may be important for quantum nondemolition measurements at the few photon limit.

  2. Detecting Neutral Atoms on an Atom Chip

    OpenAIRE

    Wilzbach, M.; Haase, A.; Schwarz, M; Heine, D.; Wicker, K.; Liu, X; Brenner, K. -H.; Groth, S.; Fernholz, Th.; Hessmo, B.; Schmiedmayer, J.

    2006-01-01

    Detecting single atoms (qubits) is a key requirement for implementing quantum information processing on an atom chip. The detector should ideally be integrated on the chip. Here we present and compare different methods capable of detecting neutral atoms on an atom chip. After a short introduction to fluorescence and absorption detection we discuss cavity enhanced detection of single atoms. In particular we concentrate on optical fiber based detectors such as fiber cavities and tapered fiber d...

  3. Traps for neutral radioactive atoms

    CERN Document Server

    Sprouse, G D; Grossman, J S; Orozco, L A; Pearson, M R

    2002-01-01

    We describe several methods for efficiently injecting a small number of radioactive atoms into a laser trap. The characteristics of laser traps that make them desirable for physics experiments are discussed and several different experimental directions are described. We describe recent experiments with the alkali element Fr and point to future directions of the neutral atom trapping program.

  4. Optimization of Neutral Atom Imagers

    Science.gov (United States)

    Shappirio, M.; Coplan, M.; Balsamo, E.; Chornay, D.; Collier, M.; Hughes, P.; Keller, J.; Ogilvie, K.; Williams, E.

    2008-01-01

    The interactions between plasma structures and neutral atom populations in interplanetary space can be effectively studied with energetic neutral atom imagers. For neutral atoms with energies less than 1 keV, the most efficient detection method that preserves direction and energy information is conversion to negative ions on surfaces. We have examined a variety of surface materials and conversion geometries in order to identify the factors that determine conversion efficiency. For chemically and physically stable surfaces smoothness is of primary importance while properties such as work function have no obvious correlation to conversion efficiency. For the noble metals, tungsten, silicon, and graphite with comparable smoothness, conversion efficiency varies by a factor of two to three. We have also examined the way in which surface conversion efficiency varies with the angle of incidence of the neutral atom and have found that the highest efficiencies are obtained at angles of incidence greater then 80deg. The conversion efficiency of silicon, tungsten and graphite were examined most closely and the energy dependent variation of conversion efficiency measured over a range of incident angles. We have also developed methods for micromachining silicon in order to reduce the volume to surface area over that of a single flat surface and have been able to reduce volume to surface area ratios by up to a factor of 60. With smooth micro-machined surfaces of the optimum geometry, conversion efficiencies can be increased by an order of magnitude over instruments like LENA on the IMAGE spacecraft without increase the instruments mass or volume.

  5. Optimization of Neutral Atom Imagers

    Science.gov (United States)

    Shappirio, M.; Coplan, M.; Balsamo, E.; Chornay, D.; Collier, M.; Hughes, P.; Keller, J.; Ogilvie, K.; Williams, E.

    2008-01-01

    The interactions between plasma structures and neutral atom populations in interplanetary space can be effectively studied with energetic neutral atom imagers. For neutral atoms with energies less than 1 keV, the most efficient detection method that preserves direction and energy information is conversion to negative ions on surfaces. We have examined a variety of surface materials and conversion geometries in order to identify the factors that determine conversion efficiency. For chemically and physically stable surfaces smoothness is of primary importance while properties such as work function have no obvious correlation to conversion efficiency. For the noble metals, tungsten, silicon, and graphite with comparable smoothness, conversion efficiency varies by a factor of two to three. We have also examined the way in which surface conversion efficiency varies with the angle of incidence of the neutral atom and have found that the highest efficiencies are obtained at angles of incidence greater then 80deg. The conversion efficiency of silicon, tungsten and graphite were examined most closely and the energy dependent variation of conversion efficiency measured over a range of incident angles. We have also developed methods for micromachining silicon in order to reduce the volume to surface area over that of a single flat surface and have been able to reduce volume to surface area ratios by up to a factor of 60. With smooth micro-machined surfaces of the optimum geometry, conversion efficiencies can be increased by an order of magnitude over instruments like LENA on the IMAGE spacecraft without increase the instruments mass or volume.

  6. Synthetic gauge potentials for ultracold neutral atoms

    Science.gov (United States)

    Lin, Yu-Ju; Spielman, I. B.

    2016-09-01

    Synthetic gauge fields for ultracold neutral atoms—engineered using the interaction between laser fields and the atoms’ internal ‘spin’ degrees of freedom—provide promising techniques for generating the large (synthetic) magnetic fields required to reach the fractional quantum Hall (FQH) limit in quantum gases, bosonic or fermionic alike. Because neutral atoms can move in a nearly disorder-free environment and they have extremely simple contact interactions, the resulting FQH states would be revealed in their most essential form. Moreover, bosonic FQH states represent a new frontier and have never been seen in any setting. Going beyond electromagnetism's conventional scalar gauge field, it is possible to create more general non-Abelian gauge potentials. When these are spatially uniform, they are equivalent to spin-orbit coupling familiar in material systems, and can lead to cold atom analogs of topological insulators and topological superconductors. In this tutorial, we introduce basic concepts underlying these gauge fields, making connections to the Aharonov-Bohm phase and geometric phase. We focus on the system of neutral atoms ‘dressed’ by multiple laser beams, where the eigenstates of the resulting Hamiltonian are known as dressed states. Synthetic gauge potentials arise from the unitary transformation required to express these dressed states in terms of the laser-free eigenstates. We discuss stability of laser-dressed atoms corresponding to the adiabatic condition and the probability of non-adiabatic transitions. Adopting both the semiclassical and quantum mechanical approaches, we demonstrate they agree in the suitable limit. We also analyze using both the conventional adiabatic picture and exact picture, where the kinetic energy is neglected in the former and retained in the latter picture.

  7. Optical nanofibres and neutral atoms

    CERN Document Server

    Nieddu, Thomas; Chormaic, Sile Nic

    2015-01-01

    Optical nanofibres are increasingly being used in cold atom experiments due to their versatility and the clear advantages they have when developing all-fibred systems for quantum technologies. They provide researchers with a method of overcoming the Rayleigh range for achieving high intensities in a focussed beam over a relatively long distance, and can act as a noninvasive tool for probing cold atoms. In this review article, we will briefly introduce the theory of mode propagation in an ultrathin optical fibre and highlight some of the more significant theoretical and experimental progresses to date, including the early work on atom probing, manipulation and trapping, the study of atom-dielectric surface interactions, and the more recent observation of nanofibre-mediated nonlinear optics phenomena in atomic media. The functionality of optical nanofibres in relation to the realisation of atom-photon hybrid quantum systems is also becoming more evident as some of the earlier technical challenges are surpassed ...

  8. Atomic Transition Probabilities for Neutral Cerium

    Science.gov (United States)

    Chisholm, John; Nitz, D.; Sobeck, J.; Den Hartog, E. A.; Wood, M. P.; Lawler, J. E.

    2010-01-01

    Among the rare earth species, the spectra of neutral cerium (Ce I) and singly ionized cerium (Ce II) are some of the most complex. Like other rare earth species, Ce has many lines in the visible which are suitable for elemental abundance studies. Recent work on Ce II transition probabilities [1] is now being augmented with similar work on Ce I for future studies using such lines from astrophysical sources. Radiative lifetimes from laser induced fluorescence measurements [2] on neutral Ce are being combined with emission branching fractions from spectra recorded using a Fourier transform spectrometer. A total of 14 high resolution spectra are being analyzed to determine branching fractions for 2500 to 3000 lines from 153 upper levels in neutral Ce. Representative data samples and progress to date will be presented. This work was supported by the National Science Foundation's REU program and the Department of Defense's ASSURE program through NSF Award AST-0453442 and NSF Grant CTS0613277. [1] J. E. Lawler, C. Sneden, J. J. Cowan, I. I. Ivans, and E. A. Den Hartog, Astrophys. J. Suppl. Ser. 182, 51-79 (2009). [2] E. A. Den Hartog, K. P. Buettner, and J. E. Lawler, J. Phys. B: Atomic, Molecular & Optical Physics 42, 085006 (7pp) (2009).

  9. Accelerating neutral atoms on a Table top

    Science.gov (United States)

    Krishnamurthy, M.; Rajendran, Rajeev; Madhu, T.; Kpm, Rishad; Narayanan, V.; Krishnakumar, E.

    2013-05-01

    Plasma accelerators driven by super strong laser fields couple unusually large energies to charged particles. Acceleration of neutral atoms from such strongly ionized plasmas have remained elusive. A laser based neutralizer can convert laser accelerated fast ion source to fast neutral atom source. We report a scheme to generate fast Argon atoms (up to 1 MeV) from an optical-field-ionized dense nano-cluster ensemble. Intense, ultrashort pulses ionize each atom in a Ar nanocluster to 8+ and coulomb explode ions to energies up to MeV. We show that in a dense cluster ensemble, the electrons that stream out of the focal volume collisionally excited clusters in the periphery of the focus to high lying Rydberg excited states and form a sheath of electronically excited clusters. Cross sections for reducing ions by charge transfer collisions are orders of magnitude larger with the electronically exited systems. Fast ions that stream through the excited cluster sheath are reduced to neutral atoms with no change in momentum. We show that the scheme can covert ions to neutral atoms with nearly 100% efficiency, transferring 8 electrons per atom in a few mm span of the supersonic jet.

  10. Optical nanofibres and neutral atoms

    Science.gov (United States)

    Nieddu, Thomas; Gokhroo, Vandna; Chormaic, Síle Nic

    2016-05-01

    Optical nanofibres are increasingly being used in cold atom experiments due to their versatility and the clear advantages they have when developing all-fibred systems for quantum technologies. They provide researchers with a method of overcoming the Rayleigh range for achieving high intensities in a focussed beam over a relatively long distance, and can act as a noninvasive tool for probing cold atoms. In this review article, we will briefly introduce the theory of mode propagation in an ultrathin optical fibre and highlight some of the more significant theoretical and experimental progresses to date, including the early work on atom probing, manipulation and trapping, the study of atom-dielectric surface interactions, and the more recent observation of nanofibre-mediated nonlinear optics phenomena in atomic media. The functionality of optical nanofibres in relation to the realisation of atom-photon hybrid quantum systems is also becoming more evident as some of the earlier technical challenges are surpassed and, recently, several schemes to implement optical memories have been proposed. We also discuss some possible directions where this research field may head, in particular, in relation to the use of optical nanofibres that can support higher-order modes with an associated orbital angular momentum.

  11. Atomic Structure Calculations for Neutral Oxygen

    OpenAIRE

    Norah Alonizan; Rabia Qindeel; Nabil Ben Nessib

    2016-01-01

    Energy levels and oscillator strengths for neutral oxygen have been calculated using the Cowan (CW), SUPERSTRUCTURE (SS), and AUTOSTRUCTURE (AS) atomic structure codes. The results obtained with these atomic codes have been compared with MCHF calculations and experimental values from the National Institute of Standards and Technology (NIST) database.

  12. On geometric factors for neutral particle analyzers.

    Science.gov (United States)

    Stagner, L; Heidbrink, W W

    2014-11-01

    Neutral particle analyzers (NPA) detect neutralized energetic particles that escape from plasmas. Geometric factors relate the counting rate of the detectors to the intensity of the particle source. Accurate geometric factors enable quick simulation of geometric effects without the need to resort to slower Monte Carlo methods. Previously derived expressions [G. R. Thomas and D. M. Willis, "Analytical derivation of the geometric factor of a particle detector having circular or rectangular geometry," J. Phys. E: Sci. Instrum. 5(3), 260 (1972); J. D. Sullivan, "Geometric factor and directional response of single and multi-element particle telescopes," Nucl. Instrum. Methods 95(1), 5-11 (1971)] for the geometric factor implicitly assume that the particle source is very far away from the detector (far-field); this excludes applications close to the detector (near-field). The far-field assumption does not hold in most fusion applications of NPA detectors. We derive, from probability theory, a generalized framework for deriving geometric factors that are valid for both near and far-field applications as well as for non-isotropic sources and nonlinear particle trajectories.

  13. A new approach to entangling neutral atoms.

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jongmin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Michael J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jau, Yuan-Yu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Deutsch, Ivan H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Biedermann, Grant W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-11-01

    Our team has developed a new approach to entangling neutral atoms with a Rydberg-dressed interaction. Entangling neutral atoms is an essential key of quantum technologies such as quantum computation, many-body quantum simulation, and high-precision atomic sensors . The demonstrated Rydberg-dressed protocol involves adiabatically imposing a light shift on the ground state by coupling an excited Rydberg state with a tuned laser field. Using this technique, we have demonstrated a strong and tunable dipole - dipole interaction between two individually trapped atoms with energy shifts of order 1 MHz, which has been challenging to achieve in other protocols . During this program, we experimentally demonstrated Bell-state entanglement and the isomorphism to the Jaynes - Cumming model of a Rydberg-dressed two-atom system. Our theoretical calculations of a CPHASE quantum logic gate and arbitrary Dicke state quantum control in this system encourage further work.

  14. Artificial electromagnetism for neutral atoms: Escher staircase and Laughlin liquids

    Science.gov (United States)

    Mueller, Erich J.

    2004-10-01

    We present a method for creating fields that couple to neutral atoms in the same way that electromagnetic fields couple to charged particles. We show that this technique opens the door for a range of neutral atom experiments, including probing the interplay between periodic potentials and quantum Hall effects. Furthermore, we propose, and analyze, seemingly paradoxical geometries which can be engineered through these techniques. For example, we show how to create a ring of sites where an atom continuously reduces its potential energy by moving in a clockwise direction.

  15. Absence of neutral alkali atoms in rhodizite

    Science.gov (United States)

    Donnay, G.; Thorpe, A.N.; Senftle, F.E.; Sioda, R.

    1966-01-01

    The formula CsB12Be4Al4O28 has been proposed by others for the mineral rhodizite. Electron-spin-resonance and magnetic susceptibility measurements prove the absence of neutral cesium atoms. An ionic formula CsB11Be4Al4O 26(OH)2is proposed.

  16. Ground Levels and Ionization Energies for the Neutral Atoms

    Science.gov (United States)

    SRD 111 Ground Levels and Ionization Energies for the Neutral Atoms (Web, free access)   Data for ground state electron configurations and ionization energies for the neutral atoms (Z = 1-104) including references.

  17. Basis-neutral Hilbert-space analyzers

    CERN Document Server

    Martin, Lane; Kondakci, H Esat; Larson, Walker D; Shabahang, Soroush; Jahromi, Ali K; Malhotra, Tanya; Vamivakas, A Nick; Atia, George K; Abouraddy, Ayman F

    2016-01-01

    Interferometry is one of the central organizing principles of optics. Key to interferometry is the concept of optical delay, which facilitates spectral analysis in terms of time-harmonics. In contrast, when analyzing a beam in a Hilbert space spanned by spatial modes -- a critical task for spatial-mode multiplexing and quantum communication -- basis-specific principles are invoked that are altogether distinct from that of `delay.' Here, we extend the traditional concept of temporal delay to the spatial domain, thereby enabling the analysis of a beam in an arbitrary spatial-mode basis -- exemplified using Hermite-Gaussian and radial Laguerre-Gaussian modes. Such generalized delays correspond to optical implementations of fractional transforms; for example, the fractional Hankel transform is the generalized delay associated with the space of Laguerre-Gaussian modes, and an interferometer incorporating such a `delay' obtains modal weights in the associated Hilbert space. By implementing an inherently stable, rec...

  18. Innershell Photoionization Studies of Neutral Atomic Nitrogen

    CERN Document Server

    Stolte, W C; Lindle, D W; Sant'Anna, M M; Savin, D W

    2014-01-01

    Innershell ionization of a $1s$ electron by either photons or electrons is important for X-ray photoionized objects such as active galactic nuclei and electron-ionized sources such as supernova remnants. Modeling and interpreting observations of such objects requires accurate predictions for the charge state distribution (CSD) which results as the $1s$-hole system stabilizes. Due to the complexity of the complete stabilization process, few modern calculations exist and the community currently relies on 40-year-old atomic data. Here, we present a combined experimental and theoretical study for innershell photoionization of neutral atomic nitrogen for photon energies of $403-475$~eV. Results are reported for the total ion yield cross section, for the branching ratios for formation of N$^+$, N$^{2+}$, and N$^{3+}$, and for the average charge state. We find significant differences when comparing to the data currently available to the astrophysics community. For example, while the branching ratio to N$^{2+}$ is so...

  19. Estimating the hydration enthalpies of neutral alkali metal atoms.

    Science.gov (United States)

    Stace, A J

    2006-10-26

    Using existing data on the ionization energies of alkali metal atoms in small clusters of water, a thermodynamic cycle is proposed from which the hydration enthalpies of the neutral metal atoms can be estimated. Where comparisons are possible, the results are in reasonable agreement with those obtained using both experimental and ab initio methods. Application of the thermodynamic cycle to neutral alkali metal atoms solvated in ammonia yields solvation enthalpies that are significantly lower than those obtained for water.

  20. Energetic neutral atoms emitted from ice by ion bombardment under Ganymede surface conditions

    Science.gov (United States)

    Wieser, Martin; Barabash, Stas; Futaana, Yoshifumi; Wurz, Peter

    2013-04-01

    Magnetospheric or solar wind ions directly interacting with a planetary surface result in backscattering or sputtering of energetic neutral atoms. One example is the solar wind interaction with the surface of the Moon, where the produced energetic neutral atoms were observed by the Sub-keV Atom Reflecting Analyzer instrument (SARA) on Chandrayaan-1. At Jupiter, magnetospheric plasma interacts in a similar way with the surface of the Galilean moons. However, the emission of energetic neutral atoms from "dirty" ices as found e.g. on Ganymede's surface is poorly understood. We set up an experiment to study the ion to surface interaction under Ganymede surface environment conditions using the unique capabilities of the MEFISTO test facility at University of Bern. Ions of various species and energies up to 33 keV/q were impacted on a block of ice made from a mixture of water, NaCl and dry ice. The energetic neutral atoms produced by the interaction were detected with the prototype of the Jovian Neutrals Analyzer instrument (JNA.) JNA is proposed as part of the Particle Environment Package (PEP) for ESA's JUICE mission to Jupiter and instrument is based on the Energetic Energetic Neutral Atom instrument (ENA) built for the BepiColombo Magnetospheric Orbiter. We present energy spectra for different ion beam species and energetic neutral atom species combinations. The data show high yields for energetic neutral atoms up to the upper end of the instrument energy range of 3.3 keV. The energy spectra of the neutral atom flux emitted from the ice could only partially be fitted by the Sigmund-Thompson formula. In some cases, but not all, a Maxwellian distribution provides a reasonable description of the data.

  1. An atomic model for neutral and singly ionized uranium

    Science.gov (United States)

    Maceda, E. L.; Miley, G. H.

    1979-01-01

    A model for the atomic levels above ground state in neutral, U(0), and singly ionized, U(+), uranium is described based on identified atomic transitions. Some 168 states in U(0) and 95 in U(+) are found. A total of 1581 atomic transitions are used to complete this process. Also discussed are the atomic inverse lifetimes and line widths for the radiative transitions as well as the electron collisional cross sections.

  2. Solid State Neutral Particle Analyzer Array on NSTX

    Science.gov (United States)

    Liu, D.; Shinohara, K.; Darrow, D. S.; Roquemore, A. L.; Medley, S. S.; Cecil, F. E.; Heidbrink, W. W.

    2004-11-01

    A Solid State Neutral Particle Analyzer (SSNPA) array has been installed on the National Spherical Torus Experiment (NSTX) to measure the energy distribution of charge exchange fast neutral particles. The array consists of four Si diode detectors on chords with fixed tangency radii (60, 90, 100, and 120 cm), which view across the three co-injection neutral beam (NB) lines. The calibrated energy range is 40 120KeV and its energy resolution is about 10KeV. Time resolved measurements have been obtained and compared with the E//B Neutral Particle Analyzer (NPA) results. It is observed that particle fluxes increase strongly and then decay rapidly to a steady level just after NB injection commences. Though this temporal behavior is also observed in the E//B NPA, it is not predicted in TRANSP simulations. In addition, the increase and decay rates in the two NPA systems are different. Example data from plasma discharges will be presented with explanations of these differences.

  3. Entanglement of two ground state neutral atoms using Rydberg blockade

    DEFF Research Database (Denmark)

    Miroshnychenko, Yevhen; Browaeys, Antoine; Evellin, Charles

    2011-01-01

    We report on our recent progress in trapping and manipulation of internal states of single neutral rubidium atoms in optical tweezers. We demonstrate the creation of an entangled state between two ground state atoms trapped in separate tweezers using the effect of Rydberg blockade. The quality of...

  4. Plasma heating with multi-MeV neutral atom beams

    Energy Technology Data Exchange (ETDEWEB)

    Grisham, L.R.; Post, D.E.; Mikkelsen, D.R.; Eubank, H.P.

    1981-10-01

    We explore the utility and feasibility of neutral beams of greater than or equal to 6 AMU formed from negative ions, and also of D/sup 0/ formed from D/sup -/. The negative ions would be accelerated to approx. 1 to 2 MeV/AMU and neutralized, whereupon the neutral atoms would be used to heat and, perhaps, to drive current in magnetically confined plasmas. Such beams appear feasible and offer the promise of significant advantages relative to conventional neutral beams based on positive deuterium ions at approx. 150 keV.

  5. Topological Quantum Information in a 3D Neutral Atom Array

    Science.gov (United States)

    2015-01-02

    v Prescribed by ANSI Std. Z39.18 12-23-2014 Final 12-01-2008-9-30-2014 ( DARPA ) TOPOLOGICAL QUANTUM INFORMATION IN A 3D NEUTRAL ATOM ARRAY FA9550-09...1-0041 David Weiss Penn State UP76XR0 AFOSR DARPA Approved for public release Work was performed to build core elements of a quantum computer...Hamiltonian within our trapped neutral atoms architecture. quantum computing, ultracold atoms David Weiss 814-861-3578 1 DARPA Final Report Grant

  6. Submicrometer position control of single trapped neutral atoms

    OpenAIRE

    Dotsenko, I.; Alt, W; Khudaverdyan, M.; Kuhr, S.; Meschede, D.; Miroshnychenko, Y.; Schrader, D.; Rauschenbeutel, A.

    2004-01-01

    We optically detect the positions of single neutral cesium atoms stored in a standing wave dipole trap with a sub-wavelength resolution of 143 nm rms. The distance between two simultaneously trapped atoms is measured with an even higher precision of 36 nm rms. We resolve the discreteness of the interatomic distances due to the 532 nm spatial period of the standing wave potential and infer the exact number of trapping potential wells separating the atoms. Finally, combining an initial position...

  7. Effect of energetic oxygen atoms on neutral density models.

    Science.gov (United States)

    Rohrbaugh, R. P.; Nisbet, J. S.

    1973-01-01

    The dissociative recombination of O2(+) and NO(+) in the F region results in the production of atomic oxygen and atomic nitrogen with substantially greater kinetic energy than the ambient atoms. In the exosphere these energetic atoms have long free paths. They can ascend to altitudes of several thousand kilometers and can travel horizontally to distances of the order of the earth's radius. The distribution of energetic oxygen atoms is derived by means of models of the ion and neutral densities for quiet and disturbed solar conditions. A distribution technique is used to study the motion of the atoms in the collision-dominated region. Ballistic trajectories are calculated in the spherical gravitational field of the earth. The present calculations show that the number densities of energetic oxygen atoms predominate over the ambient atomic oxygen densities above 1000 km under quiet solar conditions and above 1600 km under disturbed solar conditions.

  8. Neutral atomic carbon in dense molecular clouds

    Science.gov (United States)

    Zmuidzinas, J.; Betz, A. L.; Boreiko, R. T.; Goldhaber, D. M.

    1988-01-01

    The 370 micron 3P2-3P1 fine-structure line of neutral carbon was detected in seven sources: OMC 1, NGC 2024, S140, W3, DR 21, M17, and W51. Simultaneous analysis of J = 2-1 data and available observations of the J = 1-0 line make it possible to deduce optical depths and excitation temperatures for these lines. These data indicate that both C I lines are likely to be optically thin, and that the ratio of C I to CO column densities in these clouds is typically about 0.1.

  9. Neutral atom traps of rare isotopes

    Science.gov (United States)

    Mueller, Peter

    2016-09-01

    Laser cooling and trapping techniques offer exquisite control of an atom's external and internal degrees of freedom. The species of interest can be selectively captured, cooled close to absolute zero temperatures, and observed with high signal-to-noise ratio. Moreover, the atom's electronic and magnetic state populations can be precisely manipulated and interrogated. Applied in nuclear physics, these techniques are ideal for precision measurements in the fields of fundamental interactions and symmetries, nuclear structure studies, and isotopic trace analysis. In particular, they offer unique opportunities in the quest for physics beyond the standard model. I will shortly review the basics of this approach and the state of the field and then cover in more details recent results from two such efforts: the search for a permanent electric dipole moment in 225Ra and the beta-neutrino angular correlation measurement with laser trapped 6He. This work is supported by the U.S. DOE, Office of Science, Office of Nuclear Physics, under Contract DE-AC02-06CH11357.

  10. A Novel Gravito-Optical Surface Trap for Neutral Atoms

    Institute of Scientific and Technical Information of China (English)

    XIE Chun-Xia; WANG Zhengling; YIN Jian-Ping

    2006-01-01

    @@ We propose a novel gravito-optical surface trap (GOST) for neutral atoms based on one-dimensional intensity gradient cooling. The surface optical trap is composed of a blue-detuned reduced semi-Gaussian laser beam (SGB), a far-blue-detuned dark hollow beam and the gravity field.

  11. Two-Dimensional Arrays of Neutral Atom Quantum Gates

    Science.gov (United States)

    2012-10-20

    Isenhower, X. Zhang, A. Gill, T. Walker, M. Saffman. Deterministic entanglement of two neutral atoms via Rydberg blockade, Physical Review A, (09 2010...squeezing of atomic ensembles by multicolor quantum nondemolition measurements, Physical Review A, (02 2009): 0. doi: 10.1103/PhysRevA.79.023831 10/19/2012...collective encoding in holmium atoms, Physical Review A, (07 2008): 0. doi: 10.1103/PhysRevA.78.012336 10/19/2012 10.00 M Saffman, X L Zhang, A T

  12. Artificial electromagnetism for neutral atoms: Escher staircases and Laughlin liquids

    Science.gov (United States)

    Mueller, Erich J.

    2004-03-01

    Cold gas experimentalists are attempting to produce analogs of solid state systems by placing neutral atoms in periodic `optical lattice' potentials. I show how lasers can manipulate the internal states of such atoms to simulate the effects of electric and magnetic fields on charged particles. Unlike similar ideas of Jaksch and Zoller [New J. Phys. 5, 56 (2003)], an external linear potential is unnecessary. Since these effective electric and magnetic fields do not obey Maxwell's equations, seemingly paradoxical geometries are possible. For example, one can construct a ring of sites where an atoms potential energy continuously decreases as it moves in a clockwise direction.

  13. Manipulating Neutral Atoms in Chip-Based Magnetic Traps

    Science.gov (United States)

    Aveline, David; Thompson, Robert; Lundblad, Nathan; Maleki, Lute; Yu, Nan; Kohel, James

    2009-01-01

    Several techniques for manipulating neutral atoms (more precisely, ultracold clouds of neutral atoms) in chip-based magnetic traps and atomic waveguides have been demonstrated. Such traps and waveguides are promising components of future quantum sensors that would offer sensitivities much greater than those of conventional sensors. Potential applications include gyroscopy and basic research in physical phenomena that involve gravitational and/or electromagnetic fields. The developed techniques make it possible to control atoms with greater versatility and dexterity than were previously possible and, hence, can be expected to contribute to the value of chip-based magnetic traps and atomic waveguides. The basic principle of these techniques is to control gradient magnetic fields with suitable timing so as to alter a trap to exert position-, velocity-, and/or time-dependent forces on atoms in the trap to obtain desired effects. The trap magnetic fields are generated by controlled electric currents flowing in both macroscopic off-chip electromagnet coils and microscopic wires on the surface of the chip. The methods are best explained in terms of examples. Rather than simply allowing atoms to expand freely into an atomic waveguide, one can give them a controllable push by switching on an externally generated or a chip-based gradient magnetic field. This push can increase the speed of the atoms, typically from about 5 to about 20 cm/s. Applying a non-linear magnetic-field gradient exerts different forces on atoms in different positions a phenomenon that one can exploit by introducing a delay between releasing atoms into the waveguide and turning on the magnetic field.

  14. Entangling two transportable neutral atoms via local spin exchange

    Science.gov (United States)

    Kaufman, A. M.; Lester, B. J.; Foss-Feig, M.; Wall, M. L.; Rey, A. M.; Regal, C. A.

    2015-11-01

    To advance quantum information science, physical systems are sought that meet the stringent requirements for creating and preserving quantum entanglement. In atomic physics, robust two-qubit entanglement is typically achieved by strong, long-range interactions in the form of either Coulomb interactions between ions or dipolar interactions between Rydberg atoms. Although such interactions allow fast quantum gates, the interacting atoms must overcome the associated coupling to the environment and cross-talk among qubits. Local interactions, such as those requiring substantial wavefunction overlap, can alleviate these detrimental effects; however, such interactions present a new challenge: to distribute entanglement, qubits must be transported, merged for interaction, and then isolated for storage and subsequent operations. Here we show how, using a mobile optical tweezer, it is possible to prepare and locally entangle two ultracold neutral atoms, and then separate them while preserving their entanglement. Ground-state neutral atom experiments have measured dynamics consistent with spin entanglement, and have detected entanglement with macroscopic observables; we are now able to demonstrate position-resolved two-particle coherence via application of a local gradient and parity measurements. This new entanglement-verification protocol could be applied to arbitrary spin-entangled states of spatially separated atoms. The local entangling operation is achieved via spin-exchange interactions, and quantum tunnelling is used to combine and separate atoms. These techniques provide a framework for dynamically entangling remote qubits via local operations within a large-scale quantum register.

  15. Seeking to Improve Low Energy Neutral Atom Detection in Space

    Science.gov (United States)

    Shappirio, M.; Coplan, M.; Chornay, D.; Collier, M.; Herrero, F.; Ogilvie, K.; Williams, E.

    2007-01-01

    The detection of energetic neutral atoms allows for the remote examination of the interactions between plasmas and neutral populations in space. Before these neutral atoms can be measured, they must first be converted to ions. For the low energy end of this spectrum, interaction with a conversion surface is often the most efficient method to convert neutrals into ions. It is generally thought that the most efficient surfaces are low work functions materials. However, by their very nature, these surfaces are highly reactive and unstable, and therefore are not suitable for space missions where conditions cannot be controlled as they are in a laboratory. We therefore are looking to optimize a stable surface for conversion efficiency. Conversion efficiency can be increased either by changing the incident angle of the neutral particles to be grazing incidence and using stable surfaces with high conversion efficiencies. We have examined how to increase the angle of incidence from -80 degrees to -89 degrees, while maintaining or improving the total active conversion surface area without increasing the overall volume of the instrument. We are developing a method to micro-machine silicon, which will reduce the volume to surface area ratio by a factor of 60. We have also examined the material properties that affect the conversion efficiency of the surface for stable surfaces. Some of the parameters we have examined are work function, smoothness, and bond structure. We find that for stable surfaces, the most important property is the smoothness of the surface.

  16. Focused beams of fast neutral atoms in glow discharge plasma

    Science.gov (United States)

    Grigoriev, S. N.; Melnik, Yu. A.; Metel, A. S.; Volosova, M. A.

    2017-06-01

    Glow discharge with electrostatic confinement of electrons in a vacuum chamber allows plasma processing of conductive products in a wide pressure range of p = 0.01 - 5 Pa. To assist processing of a small dielectric product with a concentrated on its surface beam of fast neutral atoms, which do not cause charge effects, ions from the discharge plasma are accelerated towards the product and transformed into fast atoms. The beam is produced using a negatively biased cylindrical or a spherical grid immersed in the plasma. Ions accelerated by the grid turn into fast neutral atoms at p > 0.1 Pa due to charge exchange collisions with gas atoms in the space charge sheaths adjoining the grid. The atoms form a diverging neutral beam and a converging beam propagating from the grid in opposite directions. The beam propagating from the concave surface of a 0.24-m-wide cylindrical grid is focused on a target within a 10-mm-wide stripe, and the beam from the 0.24-m-diameter spherical grid is focused within a 10-mm-diameter circle. At the bias voltage U = 5 kV and p ˜ 0.1 Pa, the energy of fast argon atoms is distributed continuously from zero to eU ˜ 5 keV. The pressure increase to 1 Pa results in the tenfold growth of their equivalent current and a decrease in the mean energy by an order of magnitude, which substantially raises the efficiency of material etching. Sharpening by the beam of ceramic knife-blades proved that the new method for the generation of concentrated fast atom beams can be effectively used for the processing of dielectric materials in vacuum.

  17. Entangling two transportable neutral atoms via local spin exchange

    CERN Document Server

    Kaufman, A M; Foss-Feig, M; Wall, M L; Rey, A M; Regal, C A

    2015-01-01

    To advance quantum information science a constant pursuit is the search for physical systems that meet the stringent requirements for creating and preserving quantum entanglement. In atomic physics, robust two-qubit entanglement is typically achieved by strong, long-range interactions in the form of Coulomb interactions between ions or dipolar interactions between Rydberg atoms. While these interactions allow fast gates, atoms subject to these interactions must overcome the associated coupling to the environment and cross-talk among qubits. Local interactions, such as those requiring significant wavefunction overlap, can alleviate these detrimental effects yet present a new challenge: To distribute entanglement, qubits must be transported, merged for interaction, and then isolated for storage and subsequent operations. Here we show how, via a mobile optical tweezer, it is possible to prepare and locally entangle two ultracold neutral atoms, and then separate them while preserving their entanglement. While ult...

  18. Robust quantum logic in neutral atoms via adiabatic Rydberg dressing

    Science.gov (United States)

    Keating, Tyler; Cook, Robert L.; Hankin, Aaron M.; Jau, Yuan-Yu; Biedermann, Grant W.; Deutsch, Ivan H.

    2015-01-01

    We study a scheme for implementing a controlled-Z (cz) gate between two neutral-atom qubits based on the Rydberg blockade mechanism in a manner that is robust to errors caused by atomic motion. By employing adiabatic dressing of the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise because of atomic thermal motion. In addition, the adiabatic protocol allows for a Doppler-free configuration that involves counterpropagating lasers in a σ+/σ- orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces acting on doubly excited Rydberg atoms when the blockade is imperfect. For reasonable parameters, with qubits encoded into the clock states of 133Cs, we predict that our protocol could produce a cz gate in <10 μ s with error probability on the order of 10-3.

  19. Quantum Computation with Neutral Atoms at Addressable Optical Lattice Sites and Atoms in Confined Geometries

    Science.gov (United States)

    2014-10-13

    Félix Riou, Aaron Reinhard, Laura A. Zundel, David S. Weiss. Spontaneous-emission- induced transition rates between atomic states in optical lattices...complementary technique to measure the hyperfine states at each lattice site. We developed a technique to cool atoms so that they are mostly in the vibrational ...28-Feb-2013 Approved for Public Release; Distribution Unlimited Final Report: Quantum Computation with Neutral Atoms at Addressable Optical Lattice

  20. A New Instrument Design for Imaging Low Energy Neutral Atoms

    Science.gov (United States)

    Keller, John W.; Collier, Michael R.; Chornay, Dennis; Rozmarynowski, Paul; Getty, Stephanie; Cooper, John F.; Smith, Billy

    2007-01-01

    The MidSTAR-2 satellite, to be built at the US Naval Academy as a follow-on to the successful MidSTAR-1 satellite (http://web.ew.usna.edu/midstar/), will launch in 2011 and carry three Goddard Space Flight Center (GSFC) experiments developed under Goddard's Internal Research and Development (IRAD) program. One of these GSFC instruments, the Miniature Imager for Neutral Ionospheric atoms and Magnetospheric Electrons (MINI-ME) builds on the heritage of the Goddard-developed Low-Energy Neutral Atom (LENA) imager launched on the IMAGE spacecraft in 2000. MINI-ME features a Venetian-blind conversion surface assembly that improves both light rejection and conversion efficiency in a smaller and lighter package than LENA making this an highly effective instrument for viewing solar wind charge exchange with terrestrial and planetary exospheres. We will describe the MINI-ME prototyping effort and its science targets.

  1. Low energy neutral atom imaging: Remote observations of the magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Funsten, H.O.; McComas, D.J.; Scime, E.E.; Moore, K.R.

    1995-02-01

    Recent developments in detection of neutral atom imaging should enable imaging the global structure and dynamics of the terrestrial magnetosphere. The inherent technical challenge of imaging low energy neutral atoms (LENAs) with energy < 30 keV is their separation from the tremendous UV background, to which LENA detectors are sensitive, without loss of information of LENA trajectory and energy. Three instrument concepts for separating LENAs from the background UV are presented: LENA charge conversion via transmission through an ultrathin carbon foil and subsequent electrostatic deflection, EUV grating polarizers and attenuators, and high frequency shutters. Each of these concepts can be mated to a detector section that provides both LENA imaging capability and coincidence/time-of-flight.

  2. Exospheres and Energetic Neutral Atoms of Mars, Venus and Titan

    Science.gov (United States)

    Futaana, Yoshifumi; Chaufray, Jean-Yves; Smith, H. Todd; Garnier, Philippe; Lichtenegger, Herbert; Delva, Magda; Gröller, Hannes; Mura, Alessandro

    Our understanding of the upper atmosphere of unmagnetized bodies such as Mars, Venus and Titan has improved significantly in this decade. Recent observations by in situ and remote sensing instruments on board Mars Express, Venus Express and Cassini have revealed characteristics of the neutral upper atmospheres (exospheres) and of energetic neutral atoms (ENAs). The ENA environment in the vicinity of the bodies is by itself a significant study field, but ENAs are also used as a diagnostic tool for the exosphere and the interaction with the upstream plasmas. Synergy between theoretical and modeling work has also improved considerably. In this review, we summarize the recent progress of our understanding of the neutral environment in the vicinity of unmagnetized planets.

  3. Impact of Planetary Gravitation on High Precision Neutral Atom Measurements

    Science.gov (United States)

    Kucharek, H.; Galli, A.; Wurz, P.; Moebius, E.; Lee, M. A.; Park, J.; Fuselier, S. A.; Bzowski, M.; Schwadron, N.; McComas, D. J.

    2015-12-01

    Measurements of energetic neutral atoms (ENAs) have been extremely successful in providing very important information on physical processes inside and outside our heliosphere. For instance, recent IBEX observations provided new insights into the local interstellar environment and improved measurements of the interstellar He temperature, velocity, and direction of the interstellar flow vector. Since particle collisions are rare and radiation pressure is negligible for these neutrals, gravitational forces mainly determine the trajectories of neutral He atoms. Depending on the distance of an ENA to the source of a gravitational field and its relative speed and direction this can result in a significant deflection and acceleration. In this presentation we study the impact of the gravitational effects of the Earth, Moon, and Jupiter on ENA measurements performed in Earth orbit. We show that planetary gravitational effects do not significantly affect the interstellar neutral gas parameters obtained from IBEX observations. We further study the possibility whether the He focusing cone of the Sun or Jupiter could be measured by IBEX, and whether these cones could be used as an independent measure of the interstellar He temperature. These topics are of particular importance for future missions such as IMAP, which will provide ENA images for a broader energy range and with better sensitivity and resolution.

  4. Two Azimuthally Separated Regions of Cusp Ion Injection Observed via Energetic Neutral Atoms

    National Research Council Canada - National Science Library

    Abe, M; Moore, T. E; Collier, M. R; Taguchi, S

    2011-01-01

    The low-energy neutral atom (LENA) imager on the IMAGE spacecraft can detect energetic neutral atoms produced by ion injection into the cusp through a charge exchange with the Earth's hydrogen exosphere...

  5. Microwave discharge as a remote source of neutral oxygen atoms

    Directory of Open Access Journals (Sweden)

    Gregor Primc

    2011-06-01

    Full Text Available The late flowing afterglow of an oxygen plasma was used as a remote source of neutral oxygen atoms. Plasma was created via a microwave discharge in a narrow quartz glass tube with an inner diameter of 6 mm at powers between 50 W and 300 W. The tube was connected to a wider perpendicular tube with an inner diameter of 36 mm. The density of neutral oxygen atoms was measured in the wide tube about 70 cm from the discharge using a classical nickel catalytic probe. The oxygen atom density as a function of gas pressure had a well-defined maximum. The oxygen atom density can be as large as 11 × 1020 m-3. At the lowest power tested (50 W, the maximum was obtained at a pressure of about 30 Pa. However, at higher powers, the maximum shifted to higher pressures. As a result, at 300 W the maximum appeared at 60 Pa. The results can be explained through collision phenomena in gas phase and surfaces in both discharge and flowing afterglow regions, and strong pressure gradients along the narrow tube.

  6. Communication: Neutral atom imaging using a pulsed electromagnetic lens

    Science.gov (United States)

    Gardner, Jamie R.; Anciaux, Erik M.; Raizen, Mark G.

    2017-02-01

    We report on progress towards a neutral atom imaging device that will be used for chemically sensitive surface microscopy and nanofabrication. Our novel technique for improving refractive power and correcting chromatic aberration in atom lenses is based on a fundamental paradigm shift from continuous-beam focusing to a pulsed, three-dimensional approach. Simulations of this system suggest that it will pave the way toward the long-sought goal of true atom imaging on the nanoscale. Using a prototype lens with a supersonic beam of metastable neon, we have imaged complex patterns with lower distortion and higher resolution than has been shown in any previous experiment. Comparison with simulations corroborates the underlying theory and encourages further refinement of the process.

  7. Modeling Emission of Heavy Energetic Neutral Atoms from the Heliosphere

    Science.gov (United States)

    Swaczyna, Paweł; Bzowski, Maciej

    2017-09-01

    Observations of energetic neutral atoms (ENAs) are a fruitful tool for remote diagnosis of the plasma in the heliosphere and its vicinity. So far, instruments detecting ENAs from the heliosphere were configured for observations of hydrogen atoms. Here, we estimate emissions of ENAs of the heavy chemical elements helium, oxygen, nitrogen, and neon. A large portion of the heliospheric ENAs is created in the inner heliosheath from neutralized interstellar pick-up ions (PUIs). We modeled this process and calculated full-sky intensities of ENAs for energies 0.2–130 keV/nuc. We found that the largest fluxes among considered species are expected for helium, smaller for oxygen and nitrogen, and smallest for neon. The obtained intensities are 50–106 times smaller than the hydrogen ENA intensities observed by IBEX. The detection of heavy ENAs will be possible if a future ENA detector is equipped with the capability to measure the masses of observed atoms. Because of different reaction cross-sections among the different species, observations of heavy ENAs can allow for a better understanding of global structure of the heliosphere as well as the transport and energization of PUIs in the heliosphere.

  8. Neutral atom transport from the termination shock to 1 AU

    CERN Document Server

    Bzowski, M; Bzowski, Maciej; Tarnopolski, Slawomir

    2006-01-01

    Dynamics of H, D, and heavy Energetic Neutral Atoms (ENA) between the termination shock and 1 AU is discussed in the context of the forthcoming NASA SMEX mission IBEX. In particular, effects of the velocity-dependent radiation pressure on atomic trajectories are considered and ionization losses between TS and 1 AU are studied. It is shown, among others, that most of the dynamical effects and ionization losses are induced within a few AU from the Sun, which translates to the time domain into $\\sim 1 - 3$ solar rotations before detection. This loosens considerably time requirements for tracking the ionization and radiation pressure history to just prior 3 months. ENA seem excellent tracers of the processes within the heliospheric interface, with the transport effects between the termination shock and detector relatively mild and easy to account for.

  9. Magneto-optical trap for neutral mercury atoms

    Institute of Scientific and Technical Information of China (English)

    Liu Hong-Li; Yin Shi-Qi; Liu Kang-Kang; Qian Jun; Xu Zhen; Hong Tao; Wang Yu-Zhu

    2013-01-01

    Due to its low sensitivity to blackbody radiation,neutral mercury is a good candidate for the most accurate optical lattice clock.Here we report the observation of cold mercury atoms in a magneto-optical trap (MOT).Because of the high vapor pressure at room temperature,the mercury source and the cold pump were cooled down to-40 ℃ and-70 ℃,respectively,to keep the science chamber in an ultra-high vacuum of 6× 10-9 Pa.Limited by the power of the UV cooling laser,the one beam folded MOT configuration was adopted,and 1.5× 105 Hg-202 atoms were observed by fluorescence detection.

  10. Heterogeneous recombination of neutral oxygen atoms on niobium surface

    Energy Technology Data Exchange (ETDEWEB)

    Mozetic, Miran; Zalar, Anton; Cvelbar, Uros; Poberaj, Igor

    2003-04-30

    The recombination coefficient for the reaction O+O{yields}O{sub 2} on a polycrystalline niobium surface was measured at various experimental conditions. The source of O atoms was a low pressure weakly ionized highly dissociated oxygen plasma created in a RF discharge. The electron temperature in plasma was about 5 eV and the density of positive ions between 5 and 10x10{sup 15} m{sup -3}. The density of neutral oxygen atoms was measured in the afterglow with a nickel catalytic probe and was between 2.5 and 7x10{sup 21} m{sup -3}. The recombination coefficient was measured at different temperature between 420 and 620 K, and was found to be a constant within the limits of the experimental error at the value of 0.09{+-}0.018.

  11. Neutral atom beam technique enhances bioactivity of PEEK

    Energy Technology Data Exchange (ETDEWEB)

    Khoury, Joseph, E-mail: jkhoury@exogenesis.us [Exogenesis Corporation, Billerica, MA 01821 (United States); Kirkpatrick, Sean R.; Maxwell, Melissa; Cherian, Raymond E.; Kirkpatrick, Allen; Svrluga, Richard C. [Exogenesis Corporation, Billerica, MA 01821 (United States)

    2013-07-15

    Polyetheretherketone (PEEK) is currently gaining popularity in orthopedic and spinal applications but has potential drawbacks in use. PEEK is biocompatible, similar in elasticity to bone, and radiolucent; however, it has been shown to be inert and does not integrate well with bone. Recent efforts have focused on increasing the bioactivity of PEEK by modifying the surface to improve the bone-implant interface. We have employed a novel Accelerated Neutral Atom Beam technique (ANAB) to enhance the bioactivity of PEEK. ANAB employs an intense beam of cluster-like packets of accelerated unbonded neutral argon (Ar) gas atoms. These beams are created by first producing a highly energetic Gas Cluster Ion Beam (GCIB) comprised of van der Waals bonded Ar atoms, then transferring energy to the clusters so as to cause release of most of the interatomic bonds, and finally deflecting away the remaining electrically charged cluster cores of still bonded atoms. We identified that ANAB treatment of PEEK results in nanometer scale surface modifications as well as increased surface hydrophilicity. Human osteoblasts seeded onto the surface of ANAB-treated PEEK exhibited enhanced growth as compared to control PEEK as evidenced by cell proliferation assays and microscopy. This increase in bioactivity resulted in cell proliferation levels comparable to native titanium. An in vivo study using a rat calvarial critical size defect model revealed enhanced osseointegration where bone tissue formation was evident only on the ANAB treated PEEK. Taken together, these data suggest that ANAB treatment of PEEK has the potential to enhance its bioactivity, resulting in bone formation and significantly decreasing osseointegration time of orthopedic and spinal implants.

  12. Photoionization of the valence shells of the neutral tungsten atom

    CERN Document Server

    Ballance, Connor P

    2015-01-01

    Results from large-scale theoretical cross section calculations for the total photoionization of the 4f, 5s, 5p and 6s orbitals of the neutral tungsten atom using the Dirac Coulomb R-matrix approximation (DARC: Dirac-Atomic R-matrix codes) are presented. Comparisons are made with previous theoretical methods and prior experimental measurements. In previous experiments a time-resolved dual laser approach was employed for the photo-absorption of metal vapours and photo-absorption measurements on tungsten in a solid, using synchrotron radiation. The lowest ground state level of neutral tungsten is $\\rm 5p^6 5d^4 6s^2 \\; {^5}D_{\\it J}$, with $\\it J$=0, and requires only a single dipole matrix for photoionization. To make a meaningful comparison with existing experimental measurements, we statistically average the large-scale theoretical PI cross sections from the levels associated with the ground state $\\rm 5p^6 5d^4 6s^2 \\; {^5}D_{\\it J}[{\\it J}=0,1,2,3,4]$ levels and the $\\rm 5d^56s \\; ^7S_3$ excited metastable...

  13. Nanofiber-based optical trapping of cold neutral atoms

    CERN Document Server

    Vetsch, Eugen; Mitsch, Rudolf; Reitz, Daniel; Schneeweiss, Philipp; Rauschenbeutel, Arno

    2012-01-01

    We present experimental techniques and results related to the optimization and characterization of our nanofiber-based atom trap [Vetsch et al., Phys. Rev. Lett. 104, 203603 (2010)]. The atoms are confined in an optical lattice which is created using a two-color evanescent field surrounding the optical nanofiber. For this purpose, the polarization state of the trapping light fields has to be properly adjusted. We demonstrate that this can be accomplished by analyzing the light scattered by the nanofiber. Furthermore, we show that loading the nanofiber trap from a magneto-optical trap leads to sub-Doppler temperatures of the trapped atomic ensemble and yields a sub-Poissonian distribution of the number of trapped atoms per trapping site.

  14. Analyzing atomic noise with a consumer sound card

    Science.gov (United States)

    Schulte, Carsten H. H.; Müller, Georg M.; Horn, Hauke; Hübner, Jens; Oestreich, Michael

    2012-03-01

    We discuss an advanced undergraduate project on spin noise spectroscopy of atomic rubidium vapor. The spin noise is digitized using a consumer sound card and analyzed by a fast Fourier transform. Students gain competence in digital data acquisition and processing, and the idea of analyzing a noise signal is emphasized.

  15. Extremely high reflection of solar wind protons as neutral hydrogen atoms from regolith in space

    CERN Document Server

    Wieser, Martin; Futaana, Yoshifumi; Holmström, Mats; Bhardwaj, Anil; Sridharan, R; Dhanya, MB; Wurz, Peter; Schaufelberger, Audrey; Asamura, Kazushi; 10.1016/j.pss.2009.09.012

    2010-01-01

    We report on measurements of extremely high reflection rates of solar wind particles from regolith-covered lunar surfaces. Measurements by the Sub-keV Atom Reflecting Analyzer (SARA) instrument on the Indian Chandrayaan-1 spacecraft in orbit around the Moon show that up to 20% of the impinging solar wind protons are reflected from the lunar surface back to space as neutral hydrogen atoms. This finding, generally applicable to regolith-covered atmosphereless bodies, invalidates the widely accepted assumption that regolith almost completely absorbs the impinging solar wind.

  16. Array of neutral particle analyzers at DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Carolipio, E.M.; Heidbrink, W.W. [Univ. of California, Irvine, CA (United States)

    1996-12-01

    Local measurements of the fast-ion distribution in auxiliary-heated plasmas are key to understanding the behavior of energetic particles under a variety of conditions, such as beam-ion transport during Alfven instabilities and the acceleration of beam ions by fast waves. For the first time at DIII-D, line-averaged and local measurements of the energetic-particle density (for E = 5--75 keV) are possible using an array of four compact charge-exchange analyzers. The installation consists of three vertically-viewing analyzers with fixed sightlines, measuring particles with {chi} = 90{degree} (where {chi} is the angle between the particle`s velocity and the toroidal direction) and one horizontally-viewing analyzer with a variable sightline, measuring particles with 2{degree}{grave U} {chi} {acute U} 60{degree}. All the analyzers can make passive measurements while three detectors, with sightlines that intersect deuterium heating beams, can make active charge-exchange measurements.

  17. Experimental test of Bohr's complementarity principle with single neutral atoms

    Science.gov (United States)

    Wang, Zhihui; Tian, Yali; Yang, Chen; Zhang, Pengfei; Li, Gang; Zhang, Tiancai

    2016-12-01

    An experimental test of the quantum complementarity principle based on single neutral atoms trapped in a blue detuned bottle trap was here performed. A Ramsey interferometer was used to assess the wavelike behavior or particlelike behavior with second π /2 rotation on or off. The wavelike behavior or particlelike behavior is characterized by the visibility V of the interference or the predictability P of which-path information, respectively. The measured results fulfill the complementarity relation P2+V2≤1 . Imbalance losses were deliberately introduced to the system and we find the complementarity relation is then formally "violated." All the experimental results can be completely explained theoretically by quantum mechanics without considering the interference between wave and particle behaviors. This observation complements existing information concerning Bohr's complementarity principle based on wave-particle duality of a massive quantum system.

  18. Features of Low Energy Classical Bremsstrahlung From Neutral Atoms.

    Science.gov (United States)

    Florescu, A.; Obolensky, O. I.; Pratt, R. H.

    2002-05-01

    We study classical bremsstrahlung from neutral atoms and investigate the features characteristic for the low incident energy region. These features include oscillations in the energy dependence of the bremsstrahlung cross section and structures in the asymmetry parameter of radiation. We use soft-photon limit results to elucidate the physical origins of the features. We show that there is a correspondence between classical and quantum results [1]. In both cases the features result from the suppression of contributions to the radiation from certain angular momenta at certain energies. In quantum mechanics this corresponds to zeroes in certain radiation matrix elements. In the classical case the lack of contribution from some interval of angular momentum is caused by behaviors of elastic electron scattering in screened potentials. [1] A. Florescu, O. I. Obolensky, C. D. Shaffer, and R. H. Pratt 2001 AIP Conference Proceedings 576, 60-64.

  19. Kinetic Simulation and Energetic Neutral Atom Imaging of the Magnetosphere

    Science.gov (United States)

    Fok, Mei-Ching H.

    2011-01-01

    Advanced simulation tools and measurement techniques have been developed to study the dynamic magnetosphere and its response to drivers in the solar wind. The Comprehensive Ring Current Model (CRCM) is a kinetic code that solves the 3D distribution in space, energy and pitch-angle information of energetic ions and electrons. Energetic Neutral Atom (ENA) imagers have been carried in past and current satellite missions. Global morphology of energetic ions were revealed by the observed ENA images. We have combined simulation and ENA analysis techniques to study the development of ring current ions during magnetic storms and substorms. We identify the timing and location of particle injection and loss. We examine the evolution of ion energy and pitch-angle distribution during different phases of a storm. In this talk we will discuss the findings from our ring current studies and how our simulation and ENA analysis tools can be applied to the upcoming TRIO-CINAMA mission.

  20. Long-Distance Quantum Communication with Neutral Atoms

    CERN Document Server

    Razavi, M; Razavi, Mohsen; Shapiro, Jeffrey H.

    2005-01-01

    The architecture proposed by Duan, Lukin, Cirac, and Zoller (DLCZ) for long-distance quantum communication with atomic ensembles is analyzed. Its fidelity and throughput in entanglement distribution, entanglement swapping, and quantum teleportation is derived within a framework that accounts for multiple excitations in the ensembles as well as loss and asymmetries in the channel. The DLCZ performance metrics that are obtained are compared to the corresponding results for the trapped-atom quantum communication architecture that has been proposed by a team from the Massachusetts Institute of Technology and Northwestern University (MIT/NU). Both systems are found to be capable of high-fidelity entanglement distribution. However, the DLCZ scheme only provides conditional teleportation and repeater operation, whereas the MIT/NU architecture affords full Bell-state measurements on its trapped atoms. Moreover, it is shown that achieving unity conditional fidelity in DLCZ teleportation and repeater operation requires...

  1. Inner-shell Photoionization Studies of Neutral Atomic Nitrogen

    Science.gov (United States)

    Stolte, W. C.; Jonauskas, V.; Lindle, D. W.; Sant'Anna, M. M.; Savin, D. W.

    2016-02-01

    Inner-shell ionization of a 1s electron by either photons or electrons is important for X-ray photoionized objects such as active galactic nuclei and electron-ionized sources such as supernova remnants. Modeling and interpreting observations of such objects requires accurate predictions for the charge state distribution (CSD), which results as the 1s-hole system stabilizes. Due to the complexity of the complete stabilization process, few modern calculations exist and the community currently relies on 40-year-old atomic data. Here, we present a combined experimental and theoretical study for inner-shell photoionization of neutral atomic nitrogen for photon energies of 403-475 eV. Results are reported for the total ion yield cross section, for the branching ratios for formation of N+, {{{N}}}2+, and {{{N}}}3+, and for the average charge state. We find significant differences when comparing to the data currently available to the astrophysics community. For example, while the branching ratio to {{{N}}}2+ is somewhat reduced, that for N+ is greatly increased, and that to {{{N}}}3+, which was predicted to be zero, grows to ≈ 10% at the higher photon energies studied. This work demonstrates some of the shortcomings in the theoretical CSD data base for inner-shell ionization and points the way for the improvements needed to more reliably model the role of inner-shell ionization of cosmic plasmas.

  2. Detection and quantized conductance of neutral atoms near a charged carbon nanotube.

    Science.gov (United States)

    Ristroph, Trygve; Goodsell, Anne; Golovchenko, J A; Hau, Lene Vestergaard

    2005-02-18

    We describe a novel single atom detector that uses the high electric field surrounding a charged single-walled carbon nanotube to attract and subsequently field-ionize neutral atoms. A theoretical study of the field-ionization tunneling rates for atomic trajectories in the attractive potential near a nanowire shows that a broadly applicable, high spatial resolution, low-power, neutral-atom detector with nearly 100% efficiency is realizable with present-day technology. Calculations also show that the system can provide the first opportunity to study quantized conductance phenomena when detecting cold neutral atoms with mean velocities less than 15 m/s.

  3. Guiding Neutral Atoms with Two Current-Carrying Wires and a Vertical Bias Field on the Atom Chip

    Institute of Scientific and Technical Information of China (English)

    KE Min; YAN Bo; LI Xiao-Lin; WANG Yu-Zhu

    2008-01-01

    @@ We demonstrate the guiding of neutral atoms with two parallel microfabricated current-carrying wires on the atom chip and a verticai magnetic bias field.The atoms are guided along a magnetic field minimum parallel to the current-carrying wires and confined in the other two directions.We describe in detail how the precooled atoms are efficiently loaded into the two-wire guide.

  4. A compact laser-driven plasma accelerator for megaelectronvolt-energy neutral atoms

    Science.gov (United States)

    Rajeev, R.; Madhu Trivikram, T.; Rishad, K. P. M.; Narayanan, V.; Krishnakumar, E.; Krishnamurthy, M.

    2013-03-01

    Tremendous strides have been made in charged-particle acceleration using intense, ultrashort laser pulses. Accelerating neutral atoms is an important complementary technology because such particles are unaffected by electric and magnetic fields and can thus penetrate deeper into a target than ions. However, compact laser-based accelerators for neutral atoms are limited at best to millielectronvolt energies. Here, we report the generation of megaelectronvolt-energy argon atoms from an optical-field-ionized dense nanocluster ensemble. Measurements reveal that nearly every laser-accelerated ion is converted to an energetic neutral atom as a result of highly efficient electron transfer from Rydberg excited clusters, within a sheath around the laser focus. This process, although optimal in nanoclusters, is generic and adaptable to most laser-produced plasmas. Such compact laser-driven energetic neutral atom sources could have applications in fast atom lithography for surface science and tokamak diagnostics in plasma technology.

  5. Low energy neutral atom imaging on the Moon with the SARA instrument aboard Chandrayaan-1 mission

    Indian Academy of Sciences (India)

    Anil Bhardwaj; Stas Barabash; Yoshifumi Futaana; Yoichi Kazama; Kazushi Asamura; David McCann; R Sridharan; Mats Holmstrom; Peter Wurz; Rickard Lundin

    2005-12-01

    This paper reports on the Sub-keV Atom Reflecting Analyzer (SARA)experiment that will be flown on the first Indian lunar mission Chandrayaan-1.The SARA is a low energy neutral atom (LENA)imaging mass spectrometer,which will perform remote sensing of the lunar surface via detection of neutral atoms in the energy range from 10 eV to 3 keV from a 100 km polar orbit.In this report we present the basic design of the SARA experiment and discuss various scientific issues that will be addressed.The SARA instrument consists of three major subsystems:a LENA sensor (CENA),a solar wind monitor (SWIM),and a digital processing unit (DPU).SARA will be used to image the solar wind –surface interaction to study primarily the surface composition and surface magnetic anomalies and associated mini-magnetospheres.Studies of lunar exosphere sources and space weathering on the Moon will also be attempted.SARA is the first LENA imaging mass spectrometer of its kind to be flown on a space mission.A replica of SARA is planned to fly to Mercury onboard the BepiColombo mission.

  6. Coherent addressing of individual neutral atoms in a 3D optical lattice

    CERN Document Server

    Wang, Yang; Corcovilos, Theodore A; Kumar, Aishwarya; Weiss, David S

    2015-01-01

    We demonstrate arbitrary coherent addressing of individual neutral atoms in a $5\\times 5\\times 5$ array formed by an optical lattice. Addressing is accomplished using rapidly reconfigurable crossed laser beams to selectively ac Stark shift target atoms, so that only target atoms are resonant with state-changing microwaves. The effect of these targeted single qubit gates on the quantum information stored in non-targeted atoms is smaller than $3\\times 10^{-3}$ in state fidelity. This is an important step along the path of converting the scalability promise of neutral atoms into reality.

  7. Coherent Addressing of Individual Neutral Atoms in a 3D Optical Lattice.

    Science.gov (United States)

    Wang, Yang; Zhang, Xianli; Corcovilos, Theodore A; Kumar, Aishwarya; Weiss, David S

    2015-07-24

    We demonstrate arbitrary coherent addressing of individual neutral atoms in a 5×5×5 array formed by an optical lattice. Addressing is accomplished using rapidly reconfigurable crossed laser beams to selectively ac Stark shift target atoms, so that only target atoms are resonant with state-changing microwaves. The effect of these targeted single qubit gates on the quantum information stored in nontargeted atoms is smaller than 3×10^{-3} in state fidelity. This is an important step along the path of converting the scalability promise of neutral atoms into reality.

  8. Time-of-flight mass spectrographs—From ions to neutral atoms

    Science.gov (United States)

    Möbius, E.; Galvin, A. B.; Kistler, L. M.; Kucharek, H.; Popecki, M. A.

    2016-12-01

    After their introduction to space physics in the mid 1980s time-of-flight (TOF) spectrographs have become a main staple in spaceborne mass spectrometry. They have largely replaced magnetic spectrometers, except when extremely high mass resolution is required to identify complex molecules, for example, in the vicinity of comets or in planetary atmospheres. In combination with electrostatic analyzers and often solid state detectors, TOF spectrographs have become key instruments to diagnose space plasma velocity distributions, mass, and ionic charge composition. With a variety of implementation schemes that also include isochronous electric field configurations, TOF spectrographs can respond to diverse science requirements. This includes a wide range in mass resolution to allow the separation of medium heavy isotopes or to simply provide distributions of the major species, such as H, He, and O, to obtain information on source tracers or mass fluxes. With a top-hat analyzer at the front end, or in combination with deflectors for three-axis stabilized spacecraft, the distribution function of ions can be obtained with good time resolution. Most recently, the reach of TOF ion mass spectrographs has been extended to include energetic neutral atoms. After selecting the arrival direction with mechanical collimation, followed by conversion to ions, adapted TOF sensors form a new branch of the spectrograph family tree. We review the requirements, challenges, and implementation schemes for ion and neutral atom spectrographs, including potential directions for the future, while largely avoiding overlap with complementary contributions in this special issue.

  9. 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,

  10. 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,

  11. Investigation of accelerated neutral atom beams created from gas cluster ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Kirkpatrick, A., E-mail: akirkpatrick@exogenesis.us [Exogenesis Corporation, 20 Fortune Drive, Billerica, MA 01821 (United States); Kirkpatrick, S.; Walsh, M.; Chau, S.; Mack, M.; Harrison, S.; Svrluga, R.; Khoury, J. [Exogenesis Corporation, 20 Fortune Drive, Billerica, MA 01821 (United States)

    2013-07-15

    A new concept for ultra-shallow processing of surfaces known as accelerated neutral atom beam (ANAB) technique employs conversion of energetic gas cluster ions produced by the gas cluster ion beam (GCIB) method into intense collimated beams of coincident neutral gas atoms having controllable average energies from less than 10 eV per atom to beyond 100 eV per atom. A beam of accelerated gas cluster ions is first produced as is usual in GCIB, but conditions within the source ionizer and extraction regions are adjusted such that immediately after ionization and acceleration the clusters undergo collisions with non-ionized gas atoms. Energy transfer during these collisions causes the energetic cluster ions to release many of their constituent atoms. An electrostatic deflector is then used to eliminate charged species, leaving the released neutral atoms to still travel collectively at the same velocities they had as bonded components of their parent clusters. Upon target impact, the accelerated neutral atom beams produce effects similar to those normally associated with GCIB, but to shallower depths, with less surface damage and with superior subsurface interfaces. The paper discusses generation and characterization of the accelerated neutral atom beams, describes interactions of the beams with target surfaces, and presents examples of ongoing work on applications for biomedical devices.

  12. Investigation of accelerated neutral atom beams created from gas cluster ion beams

    Science.gov (United States)

    Kirkpatrick, A.; Kirkpatrick, S.; Walsh, M.; Chau, S.; Mack, M.; Harrison, S.; Svrluga, R.; Khoury, J.

    2013-07-01

    A new concept for ultra-shallow processing of surfaces known as accelerated neutral atom beam (ANAB) technique employs conversion of energetic gas cluster ions produced by the gas cluster ion beam (GCIB) method into intense collimated beams of coincident neutral gas atoms having controllable average energies from less than 10 eV per atom to beyond 100 eV per atom. A beam of accelerated gas cluster ions is first produced as is usual in GCIB, but conditions within the source ionizer and extraction regions are adjusted such that immediately after ionization and acceleration the clusters undergo collisions with non-ionized gas atoms. Energy transfer during these collisions causes the energetic cluster ions to release many of their constituent atoms. An electrostatic deflector is then used to eliminate charged species, leaving the released neutral atoms to still travel collectively at the same velocities they had as bonded components of their parent clusters. Upon target impact, the accelerated neutral atom beams produce effects similar to those normally associated with GCIB, but to shallower depths, with less surface damage and with superior subsurface interfaces. The paper discusses generation and characterization of the accelerated neutral atom beams, describes interactions of the beams with target surfaces, and presents examples of ongoing work on applications for biomedical devices.

  13. A Fiber Optic Catalytic Sensor for Neutral Atom Measurements in Oxygen Plasma

    Directory of Open Access Journals (Sweden)

    Alenka Vesel

    2012-03-01

    Full Text Available The presented sensor for neutral oxygen atom measurement in oxygen plasma is a catalytic probe which uses fiber optics and infrared detection system to measure the gray body radiation of the catalyst. The density of neutral atoms can be determined from the temperature curve of the probe, because the catalyst is heated predominantly by the dissipation of energy caused by the heterogeneous surface recombination of neutral atoms. The advantages of this sensor are that it is simple, reliable, easy to use, noninvasive, quantitative and can be used in plasma discharge regions. By using different catalyst materials the sensor can also be applied for detection of neutral atoms in other plasmas. Sensor design, operation, example measurements and new measurement procedure for systematic characterization are presented.

  14. Heliospheric Neutral Atom Spectra Between 0.01 and 6 keV fom IBEX

    Science.gov (United States)

    Fuselier, S. A.; Allegrini, F.; Bzowski, M.; Funsten, H. O.; Ghielmetti, A. G.; Gloeckler, G.; Heirtzler, D.; Janzen, P.; Kubiak, M.; Kucharek, H.; McComas, D. J.; Moebius, E.; Moore, T. E.; Petrinec, S. M.; Quinn, M.; Reisenfeld, D.; Saul, L. A.; Scheer, J. A.; Schwardron, N.; Trattner, K. J.; Vanderspek, R.; Wurz, P.

    2012-01-01

    Since 2008 December, the Interstellar Boundary Explorer (IBEX) has been making detailed observations of neutrals from the boundaries of the heliosphere using two neutral atom cameras with overlapping energy ranges. The unexpected, yet defining feature discovered by IBEX is a Ribbon that extends over the energy range from about 0.2 to 6 keV. This Ribbon is superposed on a more uniform, globally distributed heliospheric neutral population. With some important exceptions, the focus of early IBEX studies has been on neutral atoms with energies greater than approx. 0.5 keV. With nearly three years of science observations, enough low-energy neutral atom measurements have been accumulated to extend IBEX observations to energies less than approx. 0.5 keV. Using the energy overlap of the sensors to identify and remove backgrounds, energy spectra over the entire IBEX energy range are produced. However, contributions by interstellar neutrals to the energy spectrum below 0.2 keV may not be completely removed. Compared with spectra at higher energies, neutral atom spectra at lower energies do not vary much from location to location in the sky, including in the direction of the IBEX Ribbon. Neutral fluxes are used to show that low energy ions contribute approximately the same thermal pressure as higher energy ions in the heliosheath. However, contributions to the dynamic pressure are very high unless there is, for example, turbulence in the heliosheath with fluctuations of the order of 50-100 km/s.

  15. Radio-frequency dressed state potentials for neutral atoms

    CERN Document Server

    Hofferberth, S; Fischer, B; Verdu, J; Schmiedmayer, J

    2006-01-01

    Potentials for atoms can be created by external fields acting on properties like magnetic moment, charge, polarizability, or by oscillating fields which couple internal states. The most prominent realization of the latter is the optical dipole potential formed by coupling ground and electronically excited states of an atom with light. Here we present an experimental investigation of the remarkable properties of potentials derived from radio-frequency (RF) coupling between electronic ground states. The coupling is magnetic and the vector character allows to design state dependent potential landscapes. On atom chips this enables robust coherent atom manipulation on much smaller spatial scales than possible with static fields alone. We find no additional heating or collisional loss up to densities approaching $10^{15}$ atoms / cm$^3$ compared to static magnetic traps. We demonstrate the creation of Bose-Einstein condensates in RF potentials and investigate the difference in the interference between two independe...

  16. A Mass-Selective Neutral Particle Energy Analyzer with Background Rejection

    NARCIS (Netherlands)

    Vanblokland, A. A. E.; Grimbergen, T. W. M.; Vanderven, H. W.

    1992-01-01

    A mass-discriminating neutral particle spectrometer has been developed for the Rutherford scattering diagnostic at the TEXTOR tokamak. The analyzer is equipped with a momentum preselector and a triple-coincidence time-of-flight detection system providing a rejection capability for background events.

  17. Optimization of a constrained linear monochromator design for neutral atom beams.

    Science.gov (United States)

    Kaltenbacher, Thomas

    2016-04-01

    A focused ground state, neutral atom beam, exploiting its de Broglie wavelength by means of atom optics, is used for neutral atom microscopy imaging. Employing Fresnel zone plates as a lens for these beams is a well established microscopy technique. To date, even for favorable beam source conditions a minimal focus spot size of slightly below 1μm was reached. This limitation is essentially given by the intrinsic spectral purity of the beam in combination with the chromatic aberration of the diffraction based zone plate. Therefore, it is important to enhance the monochromaticity of the beam, enabling a higher spatial resolution, preferably below 100nm. We propose to increase the monochromaticity of a neutral atom beam by means of a so-called linear monochromator set-up - a Fresnel zone plate in combination with a pinhole aperture - in order to gain more than one order of magnitude in spatial resolution. This configuration is known in X-ray microscopy and has proven to be useful, but has not been applied to neutral atom beams. The main result of this work is optimal design parameters based on models for this linear monochromator set-up followed by a second zone plate for focusing. The optimization was performed for minimizing the focal spot size and maximizing the centre line intensity at the detector position for an atom beam simultaneously. The results presented in this work are for, but not limited to, a neutral helium atom beam.

  18. Entanglement of two individual neutral atoms using Rydberg blockade

    CERN Document Server

    Wilk, T; Evellin, C; Wolters, J; Miroshnychenko, Y; Grangier, P; Browaeys, A

    2009-01-01

    We report the generation of entanglement between two individual 87Rb atoms in hyperfine ground states |F=1,M=1> and |F=2,M=2> which are held in two optical tweezers separated by 4 $\\mu$m. Our scheme relies on the Rydberg blockade effect which prevents the simultaneous excitation of the two atoms to a Rydberg state. The entangled state is generated in about 200 ns using pulsed two-photon excitation. We quantify the entanglement by applying global Raman rotations on both atoms. Correcting for losses we measure a fidelity of 0.75 with respect to the target state.

  19. Entanglement of two individual neutral atoms using Rydberg blockade.

    Science.gov (United States)

    Wilk, T; Gaëtan, A; Evellin, C; Wolters, J; Miroshnychenko, Y; Grangier, P; Browaeys, A

    2010-01-08

    We report the generation of entanglement between two individual 87Rb atoms in hyperfine ground states |F=1,M=1> and |F=2,M=2> which are held in two optical tweezers separated by 4 microm. Our scheme relies on the Rydberg blockade effect which prevents the simultaneous excitation of the two atoms to a Rydberg state. The entangled state is generated in about 200 ns using pulsed two-photon excitation. We quantify the entanglement by applying global Raman rotations on both atoms. We measure that 61% of the initial pairs of atoms are still present at the end of the entangling sequence. These pairs are in the target entangled state with a fidelity of 0.75.

  20. Charge-Exchange Neutral Particle Analyzer Diagnostic of TJ-II

    Energy Technology Data Exchange (ETDEWEB)

    Fontdecaba, J. M.; Balbin, R.; Petrov, S.; TJ-II team

    2003-07-01

    A description of the Charge Exchange Neutral Particle Analyzers in operation in the heliac flexible TJ-II is reported. A description of the detectors, as well as the operation characteristics, hardware and software used in the control and analysis of the data obtained with the diagnostic is detailed. Two NPAs are in operation in TJ-II. One of them is a 5-channel analyzer and another one is an Acord-12. The 5-channel analyzer provides measurements of charge exchange neutral fluxes at five energy channels, whereas the Acord-12 can measure simultaneously two different hydrogen isotopes (H and D) at six energy channels. Their lines of sight can be varied poloidally in order to observe the different sections of the plasma. (Author) 10 refs.

  1. Several atomic-physics issues connected with the use of neutral beams in fusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Post, D.E.; Grisham, L.R.; Fonck, R.J.

    1982-08-01

    Energetic neutral beams are used for heating and diagnostics in present magnetic fusion experiments. They are also being considered for use in future large experiments. Atomic physics issues are important for both the production of the neutral beams and the interaction of the beams and the plasma. Interest in neutral beams based on negative hydrogen ions is growing, largely based on advances in producing high current ion sources. An extension of the negative ion approach has been the suggestion to use negative ions of Z > 1 elements, such as carbon and oxygen, to form high power neutral beams for plasma heating.

  2. Ultrafast Quantum State Control of a Single Trapped Neutral Atom

    CERN Document Server

    Jones, M P A; Ga"etan, A; Zhang, J; Messin, G; Browaeys, A; Grangier, P; Jones, Matthew P. A.; Beugnon, Jerome; Ga\\"{e}tan, Alpha; Zhang, Junxiang; Messin, Gaetan; Browaeys, Antoine; Grangier, Philippe

    2006-01-01

    We demonstrate the initialisation, read-out and high-speed manipulation of a qubit stored in a single 87 Rb atom trapped in a submicron-size optical tweezer. Single qubit rotations are performed on a sub-100 ns time scale using two-photon Raman transitions. Using the ``spin-echo'' technique, we measure an irreversible dephasing time of 34 ms. The read-out of the single atom qubit is at the quantum projection noise limit when averaging up to 1000 individual events.

  3. Radiofrequency-dressed-state potentials for neutral atoms

    DEFF Research Database (Denmark)

    Hofferberth, S.; Lesanovsky, Igor; Fischer, B.

    2006-01-01

    Potentials for atoms can be created by external fields acting on properties such as magnetic moment, charge, polarizability, or by oscillating fields that couple internal states. The most prominent realization of the latter is the optical dipole potential formed by coupling ground and electronica......Potentials for atoms can be created by external fields acting on properties such as magnetic moment, charge, polarizability, or by oscillating fields that couple internal states. The most prominent realization of the latter is the optical dipole potential formed by coupling ground...... and electronically excited states of an atom with light. Here, we present an extensive experimental analysis of potentials derived from radiofrequency (RF) coupling of electronic ground states. The coupling is magnetic and the vector character allows the design of versatile microscopic state-dependent potential...... landscapes. Compared with standard magnetic trapping, we find no additional heating or (collisional) loss up to densities of 1015 atoms cm-3. We demonstrate robust evaporative cooling in RF potentials, which allows easy production of Bose-Einstein condensates in complex potentials. Altogether, this makes RF...

  4. Quantum Computation and Simulation Using Neutral Fermionic Atoms

    Science.gov (United States)

    2014-06-06

    State Laser Source for Laser Cooling of Lithium , 39th Annual Meeting of the APS Division of Atomic, Molecular, and Optical Physics. 27-MAY-08...Prof. Lincoln Carr and Laith Haddad from the Colorado School of Mines , we have proposed a method to excite relativistic vortices in a Bose-Einstein...Savard, S. Bali, C. Freed, and J. Thomas, “Ultrastable CO2 laser trapping of lithium fermions,” Phys. Rev. Lett. 82, 4204–4207 (1999). [5] L. Carr

  5. Pickup Ion Production in the Global Heliosphere and Heliosheath and Their Diagnostics by Fluxes of Energetic Neutral Atoms

    Science.gov (United States)

    Wu, Y.

    2015-12-01

    An anisotropic particle transport model, based on an expansion of a focused transport equation in Legendre polynomials, is used here as a tool to analyze the distributions of pickup ions (PUIs) in the heliosphere and heliosheath. A three-dimensional, MHD-kinetic model for flows of a thermal plasma, neutral atoms and PUIs has been developed. The preliminary results from our model are in qualitative agreement with observations made by New Horizons, Ulysses, Voyager 1 and 2. All-sky maps of energetic neutral atoms (ENA) fluxes with energies of about 0.2-6 keV based on our current PUI model are qualitatively similar to IBEX-Hi distributed ENA maps. Also, simulated spectra of ENA fluxes nearly match IBEX-Hi spectra of distributed ENA fluxes. It is demonstrated that preserving some pitch-angle information of the PUI distribution is important for correctly interpreting the data.

  6. Mars Express/ASPERA-3/NPI and IMAGE/LENA observations of energetic neutral atoms in Earth and Mars orbit

    CERN Document Server

    Holmstrom, M; Barabash, S; Brinkfeldt, K; Moore, T E; Simpson, D

    2007-01-01

    The low energy neutral atom imagers on Mars Express and IMAGE have revealed that the neutral atom populations in interplanetary space come from a variety of sources and challenge our current understanding of heliospheric physics. For example, both in cruise phase and at Mars, the neutral particle instrument NPD on Mars Express observed "unexplained neutral beams" unrelated to Mars which appear to be either of heliospheric or solar wind origin. Likewise, the NPI instrument on Mars Express has revealed streams of neutral atoms with different properties than those observed by NPD. Independently, IMAGE/LENA has reported neutral atom observations that may be interpreted as a "secondary stream" having different characteristics and flowing from a higher ecliptic longitude than the nominal upstream direction. Both sets of observations do not appear to fit in easily with the neutral atom environment from 1.0-1.57 AU as it is currently understood. In this paper we examine some highly suggestive similarities in the IMAG...

  7. Interaction of neutral atoms and plasma turbulence in the tokamak edge region

    OpenAIRE

    Wersal, Christoph; Ricci, Paolo; Jorge, Rogério; Morales, Jorge; Paruta, Paola; Riva, Fabio

    2016-01-01

    A novel first-principles self-consistent model that couples plasma and neutral atom physics suitable for the simulation of turbulent plasma behaviour in the tokamak edge region has been developed and implemented in the GBS code. While the plasma is modelled by the drift-reduced two fluid Braginskii equations, a kinetic model is used for the neutrals, valid in short and in long mean free path scenarios. The model includes ionization, charge-exchange, recombination, and elastic collisional proc...

  8. First results from solid state neutral particle analyzer on experimental advanced superconducting tokamak

    Science.gov (United States)

    Zhang, J. Z.; Zhu, Y. B.; Zhao, J. L.; Wan, B. N.; Li, J. G.; Heidbrink, W. W.

    2016-11-01

    Full function integrated, compact solid state neutral particle analyzers (ssNPA) based on absolute extreme ultraviolet silicon photodiode have been successfully implemented on the experimental advanced superconducting tokamak to measure energetic particle. The ssNPA system has been operated in advanced current mode with fast temporal and spatial resolution capabilities, with both active and passive charge exchange measurements. It is found that the ssNPA flux signals are increased substantially with neutral beam injection (NBI). The horizontal active array responds to modulated NBI beam promptly, while weaker change is presented on passive array. Compared to near-perpendicular beam, near-tangential beam brings more passive ssNPA flux and a broader profile, while no clear difference is observed on active ssNPA flux and its profile. Significantly enhanced intensities on some ssNPA channels have been observed during ion cyclotron resonant heating.

  9. Solar ions in the heliosheath: a possible new source of heavy neutral atoms

    CERN Document Server

    Grzedzielski, S; Bzowski, M; Izmodenov, V

    2006-01-01

    We show that multiply ionized coronal C, N, O, Mg, Si, S ions carried by the solar wind and neutralized by consecutive electron captures from neutral interstellar atoms constitute an important new source of neutral atoms in the inner heliosheath, with energies up to ~ 1 keV/n. In the model we developed, the heavy ions are treated as test particles carried by hydrodynamic plasma flow (with a Monte-Carlo description of interstellar neutrals) and undergoing all relevant atomic processes determining the evolution of all charge-states of considered species (radiative and dielectronic recombination, charge exchange, photo-, and electron impact ionization). The total strength of the source is from ~10^6 g/s for S to ~10^8 g/s for O, deposited as neutrals below the heliopause. These atoms should provide, as they drift to supersonic wind region, important sources of PUIs and eventually ACRs, especially for species that are excluded from entering the heliosphere because of their ionization in the LISM. The expected cor...

  10. Laser cooling a neutral atom to the three-dimensional vibrational ground state of an optical tweezer

    CERN Document Server

    Kaufman, Adam M; Regal, Cindy A

    2012-01-01

    We report three-dimensional ground state cooling of a single neutral atom in an optical tweezer. After employing Raman sideband cooling for 33 ms, we measure via sideband spectroscopy a three-dimensional ground state occupation of ~90%. Ground state neutral atoms in optical tweezers will be instrumental in numerous quantum logic applications and for nanophotonic interfaces that require a versatile platform for storing, moving, and manipulating ultracold single neutral atoms.

  11. Excitation and charge transfer in low-energy hydrogen atom collisions with neutral atoms: Theory, comparisons, and application to Ca

    CERN Document Server

    Barklem, Paul S

    2016-01-01

    A theoretical method for the estimation of cross sections and rates for excitation and charge transfer processes in low-energy hydrogen atom collisions with neutral atoms, based on an asymptotic two-electron model of ionic-covalent interactions in the neutral atom-hydrogen atom system, is presented. The calculation of potentials and non-adiabatic radial couplings using the method is demonstrated. The potentials are used together with the multi-channel Landau-Zener model to calculate cross sections and rate coefficients. The main feature of the method is that it employs asymptotically exact atomic wavefunctions, which can be determined from known atomic parameters. The method is applied to Li+H, Na+H, and Mg+H collisions, and the results compare well with existing detailed full-quantum calculations. The method is applied to the astrophysically important problem of Ca+H collisions, and rate coefficients are calculated for temperatures in the range 1000-20000 K.

  12. de Haas-van Alphen oscillations for neutral atoms in electric fields

    Science.gov (United States)

    Farias, B.; Furtado, C.

    2016-07-01

    The de Haas-van Alphen (dHvA) effect is well known as an oscillatory variation of the magnetization of conductors as a function of the inverse magnetic field and the frequency is proportional to the area of the Fermi surface. Here, we show that an analogous effect can occur for neutral atoms with a nonvanishing magnetic moment interacting with an electric field. Under an appropriate field-dipole configuration, the neutral atoms subject to a synthetic magnetic field arrange themselves in Landau levels. Using the Landau-Aharonov-Casher (LAC) theory, we obtain the energy eigenfunctions and eigenvalues as well as the degeneracy of the system. In a strong effective magnetic field regime we present the quantum oscillations in the energy and effective magnetization of a two-dimensional (2D) atomic gas. From the dHvA period we determine the area of the Fermi circle of the atomic cloud.

  13. Site Specificity in Femtosecond Laser Desorption of Neutral H Atoms from Graphite(0001)

    DEFF Research Database (Denmark)

    Frigge, R.; Hoger, T.; Siemer, B.;

    2010-01-01

    Femtosecond laser excitation and density functional theory reveal site and vibrational state specificity in neutral atomic hydrogen desorption from graphite induced by multiple electronic transitions. Multimodal velocity distributions witness the participation of ortho and para pair states...... of chemisorbed hydrogen in the desorption process. Very slow velocities of 700 and 400  ms-1 for H and D atoms are associated with the desorption out of the highest vibrational state of a barrierless potential....

  14. Cross-sections for neutral atoms and molecules collisions with charged spherical nanoparticle

    CERN Document Server

    Shneider, M N

    2016-01-01

    The paper presents cross sections for collisions of neutral atoms/molecules with a charged nanoparticle, which is the source of the dipole potential. The accuracy of the orbital limited motion (OLM) approximation is estimated. It is shown that simple analytical formulas for the atoms/molecules and heat fluxes, obtained in the OLM approximation, give an error of not more than 15%, and are applicable in all reasonable range of nanoparticles and weakly ionized plasma parameters.

  15. Interaction of neutral atoms and plasma turbulence in the tokamak edge region

    Science.gov (United States)

    Wersal, Christoph; Ricci, Paolo; Jorge, Rogerio; Morales, Jorge; Paruta, Paola; Riva, Fabio

    2016-10-01

    A novel first-principles self-consistent model that couples plasma and neutral atom physics suitable for the simulation of turbulent plasma behaviour in the tokamak edge region has been developed and implemented in the GBS code. While the plasma is modelled by the drift-reduced two fluid Braginskii equations, a kinetic model is used for the neutrals, valid in short and in long mean free path scenarios. The model includes ionization, charge-exchange, recombination, and elastic collisional processes. The model was used to study the transition form the sheath to the conduction limited regime, to include gas puffs in the simulations, and to investigate the interplay between neutral atoms and plasma turbulence.

  16. Can IBEX Identify Variations in the Galactic Environment of the Sun using Energetic Neutral Atom (ENAs)?

    CERN Document Server

    Frisch, P C; Pogorelov, N V; DeMajistre, B; Crew, G B; Funsten, H O; Janzen, P; McComas, D J; Moebius, E; Mueller, H -R; Reisenfeld, D B; Schwadron, N A; Slavin, J D; Zank, G P

    2010-01-01

    The Interstellar Boundary Explorer (IBEX) spacecraft is providing the first all-sky maps of the energetic neutral atoms (ENAs) produced by charge-exchange between interstellar neutral \\HI\\ atoms and heliospheric solar wind and pickup ions in the heliosphere boundary regions. The 'edge' of the interstellar cloud presently surrounding the heliosphere extends less than 0.1 pc in the upwind direction, terminating at an unknown distance, indicating that the outer boundary conditions of the heliosphere could change during the lifetime of the IBEX satellite. Using reasonable values for future outer heliosphere boundary conditions, ENA fluxes are predicted for one possible source of ENAs coming from outside of the heliopause. The ENA production simulations use three-dimensional MHD plasma models of the heliosphere that include a kinetic description of neutrals and a Lorentzian distribution for ions. Based on this ENA production model, it is then shown that the sensitivities of the IBEX 1.1 keV skymaps are sufficient ...

  17. Quantum states of neutral atoms bound in the magnetic field of a Kepler-guide

    Institute of Scientific and Technical Information of China (English)

    HE Ming; WANG Jin; ZHAN Ming-sheng

    2003-01-01

    The spectrum and the wave function of neutral atoms in the magnetic field of a Kepler-guide are presented by reducing a two-dimensional stationary Schrdinger equation to a one-dimensional hydrogen atom in Rydberg states. In addition, we set the scale for the atomic orbits and binding energy i n the quantum regime, and compare it with the outcome of the experiment. At the same time, we find that reducing the current and radius of the wire properly wil l increase the loading efficiency of the Kepler-guide.

  18. Universal gates based on targeted phase shifts in a 3D neutral atom array

    Science.gov (United States)

    Kumar, Aishwarya; Wang, Yang; Wu, Tsung-Yao; Weiss, David

    2016-05-01

    We demonstrate a new approach to making targeted single qubit gates using Cesium atoms in a 5x5x5 3D neutral atom array. It combines targeted AC Zeeman phase shifts with global microwave pulses to produce arbitrary single qubit gates. Non-targeted atoms are left virtually untouched by the gates. We have addressed 48 sites, targeted individually, in a 40% full array. We have also performed Randomized Benchmarking to characterize the fidelity and crosstalk errors of this gate. These gates are highly insensitive to addressing beam imperfections and can be applied to other systems and geometries. Supported by NSF.

  19. Spectroscopy, Manipulation and Trapping of Neutral Atoms, Molecules, and Other Particles Using Optical Nanofibers: A Review

    Science.gov (United States)

    Morrissey, Michael J.; Deasy, Kieran; Frawley, Mary; Kumar, Ravi; Prel, Eugen; Russell, Laura; Truong, Viet Giang; Chormaic, Síle Nic

    2013-01-01

    The use of tapered optical fibers, i.e., optical nanofibers, for spectroscopy and the detection of small numbers of particles, such as neutral atoms or molecules, has been gaining interest in recent years. In this review, we briefly introduce the optical nanofiber, its fabrication, and optical mode propagation within. We discuss recent progress on the integration of optical nanofibers into laser-cooled atom and vapor systems, paying particular attention to spectroscopy, cold atom cloud characterization, and optical trapping schemes. Next, a natural extension of this work to molecules is introduced. Finally, we consider several alternatives to optical nanofibers that display some advantages for specific applications. PMID:23945738

  20. Spectroscopy, Manipulation and Trapping of Neutral Atoms, Molecules, and Other Particles using Optical Nanofibers: A Review

    CERN Document Server

    Morrissey, Michael J; Frawley, Mary; Kumar, Ravi; Prel, Eugen; Russell, Laura; Truong, Viet Giang; Chormaic, Síle Nic

    2013-01-01

    The use of tapered optical fibers, i.e., optical nanofibers, for spectroscopy and the detection of small numbers of particles, such as neutral atoms or molecules, has been gaining ground in recent years. In this review, we briefly introduce the optical nanofiber, its fabrication and optical mode propagation within. We discuss recent progress on the integration of optical nanofibers into laser-cooled atom and vapor systems, paying particular attention to spectroscopy, cold atom cloud characterization and optical trapping schemes. Next, a natural extension on this work to molecules will be introduced. Finally, we consider several alternatives to optical nanofibers that display some advantages for particular applications.

  1. Spectroscopy, Manipulation and Trapping of Neutral Atoms, Molecules, and Other Particles Using Optical Nanofibers: A Review

    Directory of Open Access Journals (Sweden)

    Síle Nic Chormaic

    2013-08-01

    Full Text Available The use of tapered optical fibers, i.e., optical nanofibers, for spectroscopy and the detection of small numbers of particles, such as neutral atoms or molecules, has been gaining interest in recent years. In this review, we briefly introduce the optical nanofiber, its fabrication, and optical mode propagation within. We discuss recent progress on the integration of optical nanofibers into laser-cooled atom and vapor systems, paying particular attention to spectroscopy, cold atom cloud characterization, and optical trapping schemes. Next, a natural extension of this work to molecules is introduced. Finally, we consider several alternatives to optical nanofibers that display some advantages for specific applications.

  2. A mass resolved, high resolution neutral particle analyzer for C-2U

    Science.gov (United States)

    Clary, R.; Roquemore, A.; Douglass, J.; Jaramillo, D.; Korepanov, S.; Magee, R.; Medley, S.; Smirnov, A.

    2016-11-01

    C-2U is a high-confinement, advanced beam driven field-reversed configuration plasma experiment which sustains the configuration for >5 ms, in excess of typical MHD and fast particle instability times, as well as fast particle slowing down times. Fast particle dynamics are critical to C-2U performance and several diagnostics have been deployed to characterize the fast particle population, including neutron and proton detectors. To increase our understanding of fast particle behavior and supplement existing diagnostics, an E ∥ B neutral particle analyzer was installed, which simultaneously measures H0 and D0 flux with large dynamic range and high energy resolution. Here we report the commissioning of the E ∥ B analyzer, confirm the instrument has energy resolution Δ E / E ≲ 0 . 1 and a dynamic range E max / E min ˜ 30 , and present measurements of initial testing on C-2U.

  3. An unexplained 10-40° shift in the location of some diverse neutral atom data at 1 AU

    Science.gov (United States)

    Collier, Michael R.; Moore, Thomas E.; Simpson, David; Roberts, Aaron; Szabo, Adam; Fuselier, Stephen; Wurz, Peter; Lee, Martin A.; Tsurutani, Bruce T.

    2004-01-01

    Four different data sets pertaining to the neutral atom environment at 1 AU are presented and discussed. These data sets include neutral solar wind and interstellar neutral atom data from IMAGE/LENA, energetic hydrogen atom data from SOHO/HSTOF and plasma wave data from the magnetometer on ISEE-3. Surprisingly, these data sets are centered between 262° and 292° ecliptic longitude, ˜10-40° from the upstream interstellar neutral (ISN) flow direction at 254° resulting from the motion of the Sun relative to the local interstellar cloud (LIC). Some possible explanations for this offset, none of which is completely satisfactory, are discussed.

  4. An Unexplained 10 Degree - 40 Degree Shift in the Location of Some Diverse Neutral Atom Data at 1 AU

    CERN Document Server

    Collier, M; Simpson, D; Roberts, A; Szabo, A P; Fuselier, S; Wurz, P; Lee, M A; Tsurutani, B T; Collier, Michael R.; Moore, Thomas E.; Simpson, David; Roberts, Aaron; Szabo, Adam; Fuselier, Stephen; Wurz, Peter; Lee, Martin A.; Tsurutani, Bruce T.

    2003-01-01

    Four different data sets pertaining to the neutral atom environment at 1 AU are presented and discussed. These data sets include neutral solar wind and interstellar neutral atom data from IMAGE/LENA, energetic hydrogen atom data from SOHO/HSTOF and plasma wave data from the magnetometer on ISEE-3. Surprisingly, these data sets are centered between 262 degrees and 292 degrees ecliptic longitude, about 10 degrees - 40 degrees from the upstream interstellar neutral flow direction at 254 degrees resulting from the motion of the Sun relative to the local interstellar cloud. Some possible explanations for this offset, none of which is completely satisfactory, are discussed.

  5. The Sub-keV Atom Reflecting Analyzer (SARA) Experiment Aboard Chandrayaan-1 Mission: Instrument and Observations

    CERN Document Server

    Bhardwaj, Anil; Dhanya, M B; Barabash, Stas; Yoshifumi, Futaana; Holmstrom, Mats; Sridharan, R; Wurz, Peter; Schaufelberger, Audrey; Kazushi, Asamura

    2010-01-01

    SARA experiment aboard the first Indian lunar mission Chandrayaan-1 had the objective to explore the solar wind-lunar interaction using energetic neutral atoms (ENA) from the lunar surface as diagnostic tool. SARA consisted of an ENA imaging mass analyzer CENA (Chandrayaan-1 Energetic Neutral Analyzer) and an ion mass analyser SWIM (Solar Wind Monitor), along with a digital processing unit (DPU) which commands and controls the sensors and provides the interface to the spacecraft. Both sensors have provided excellent observational data. CENA has observed ENAs from the lunar surface and found that ~20% of the incident solar wind ions get backscattered as ENAs from the lunar surface. This is contrary to the previous assumptions of almost complete absorption of solar wind by the lunar surface. The observation is relevant for other airless bodies in the solar system.

  6. A solenoidal synthetic field and the non-Abelian Aharonov-Bohm effects in neutral atoms

    Science.gov (United States)

    Huo, Ming-Xia; Nie, Wei; Hutchinson, David A. W.; Kwek, Leong Chuan

    2014-08-01

    Cold neutral atoms provide a versatile and controllable platform for emulating various quantum systems. Despite efforts to develop artificial gauge fields in these systems, realizing a unique ideal-solenoid-shaped magnetic field within the quantum domain in any real-world physical system remains elusive. Here we propose a scheme to generate a ``hairline'' solenoid with an extremely small size around 1 micrometer which is smaller than the typical coherence length in cold atoms. Correspondingly, interference effects will play a role in transport. Despite the small size, the magnetic flux imposed on the atoms is very large thanks to the very strong field generated inside the solenoid. By arranging different sets of Laguerre-Gauss (LG) lasers, the generation of Abelian and non-Abelian SU(2) lattice gauge fields is proposed for neutral atoms in ring- and square-shaped optical lattices. As an application, interference patterns of the magnetic type-I Aharonov-Bohm (AB) effect are obtained by evolving atoms along a circle over several tens of lattice cells. During the evolution, the quantum coherence is maintained and the atoms are exposed to a large magnetic flux. The scheme requires only standard optical access, and is robust to weak particle interactions.

  7. A solenoidal synthetic field and the non-Abelian Aharonov-Bohm effects in neutral atoms.

    Science.gov (United States)

    Huo, Ming-Xia; Nie, Wei; Hutchinson, David A W; Kwek, Leong Chuan

    2014-08-08

    Cold neutral atoms provide a versatile and controllable platform for emulating various quantum systems. Despite efforts to develop artificial gauge fields in these systems, realizing a unique ideal-solenoid-shaped magnetic field within the quantum domain in any real-world physical system remains elusive. Here we propose a scheme to generate a "hairline" solenoid with an extremely small size around 1 micrometer which is smaller than the typical coherence length in cold atoms. Correspondingly, interference effects will play a role in transport. Despite the small size, the magnetic flux imposed on the atoms is very large thanks to the very strong field generated inside the solenoid. By arranging different sets of Laguerre-Gauss (LG) lasers, the generation of Abelian and non-Abelian SU(2) lattice gauge fields is proposed for neutral atoms in ring- and square-shaped optical lattices. As an application, interference patterns of the magnetic type-I Aharonov-Bohm (AB) effect are obtained by evolving atoms along a circle over several tens of lattice cells. During the evolution, the quantum coherence is maintained and the atoms are exposed to a large magnetic flux. The scheme requires only standard optical access, and is robust to weak particle interactions.

  8. VISIONS: Remote Observations of a Spatially-Structured Filamentary Source of Energetic Neutral Atoms near the Polar Cap Boundary During an Auroral Substorm

    Science.gov (United States)

    Collier, Michael R.; Chornay, D.; Clemmons, J.; Keller, J. W.; Klenzing, J.; Kujawski, J.; McLain, J.; Pfaff, R.; Rowland, D.; Zettergren, M.

    2015-01-01

    We report initial results from the VISualizing Ion Outflow via Neutral atom imaging during a Substorm (VISIONS) rocket that flew through and near several regions of enhanced auroral activity and also sensed regions of ion outflow both remotely and directly. The observed neutral atom fluxes were largest at the lower energies and generally higher in the auroral zone than in the polar cap. In this paper, we focus on data from the latter half of the VISIONS trajectory when the rocket traversed the polar cap region. During this period, many of the energetic neutral atom spectra show a peak at 100 electronvolts. Spectra with peaks around 100 electronvolts are also observed in the Electrostatic Ion Analyzer (EIA) data consistent with these ions comprising the source population for the energetic neutral atoms. The EIA observations of this low energy population extend only over a few tens of kilometers. Furthermore, the directionality of the arriving energetic neutral atoms is consistent with either this spatially localized source of energetic ions extending from as low as about 300 kilometers up to above 600 kilometers or a larger source of energetic ions to the southwest.

  9. ELENA MCP detector: absolute efficiency measurement for low energy neutral atoms

    Science.gov (United States)

    Rispoli, R.; De Angelis, E.; Colasanti, L.; Vertolli, N.; Orsini, S.; Scheer, J.; Mura, A.; Milillo, A.; Wurz, P.; Selci, S.; Di Lellis, A. M.; Leoni, R.; D'Alessandro, M.; Mattioli, F.; Cibella, S.

    2012-04-01

    MicroChannel plates (MCP) detectors are frequently used in space instrumentation for detecting a wide range of radiation and particles. In particular, the capability to detect non-thermal low energy neutral species is crucial for the sensor ELENA (Emitted Low-Energy Neutral Atoms), part of the package SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) on board the BepiColombo mission to Mercury to be launched in 2014. ELENA is a TOF sensor, based on a novel concept ultra-sonic oscillating shutter (Start section)which is operated at frequencies up to 50 kHz; a MCP detector is used as a Stop section. It is aimed to detect neutral atoms in the range 10 eV - 5 keV, within 70° FOV, perpendicular to the S/C orbital plane. ELENA will monitor the emission of neutral atoms from the whole surface of Mercury thanks to the spacecraft motion. The major scientific objectives are the interaction between the environment and the planet, the global particle loss-rate and the remote sensing of the surface properties. In particular, surface release processes are investigated by identifying particles release from the surface, via solar wind-induced ion sputtering (100 eV) as well as Hydrogen back-scattered at hundreds eV. MCP absolute detection efficiency for very low energy neutral atoms (EMEFISTO facility of the Physical Institute of University of Bern (CH), measurements on three different type of MCPs coating have been performed providing the behaviors of MCP detection efficiency in the range 10eV-1keV. Outcomes from such measurements are here discussed.

  10. Energetic Neutral Atom Imaging of the Lunar Poles and Night-Side

    Science.gov (United States)

    Vorburger, Audrey; Wurz, Peter; Barabash, Stas; Wieser, Martin; Futaana, Yoshifumi; Bhardwaj, Anil; Dhanya, Mb; Asamura, Kazushi

    2016-04-01

    So far all reported scientific results derived from measurements of the Chandrayaan-1 Energetic Neutral Analyzer (CENA) on board the Indian lunar mission Chandrayaan-1 focused on the sun-lit part of the Moon. Here, for the first time, we present the analysis of the Moon - solar wind interaction in Energetic Neutral Atoms (ENAs) from measurements over the poles and the night-side of the Moon. The Moon, not being protected by a global magnetic field or an atmosphere, is constantly bombarded by solar wind ions. Until recently, it was tacitly assumed that the solar wind ions that impinge onto the lunar surface are almost completely absorbed ( ENA sensors of NASA's Interstellar Boundary Explorer and by Chandrayaan-1/CENA showed an average global energetic neutral atom (ENA) albedo of 10% - 20% (e.g. McComas et al. [Geophys. Res. Lett., 2009], Wieser et al. [Planet. Space Sci., 2009], Vorburger et al. [J. Geophys. Res., 2013]). In the past 6 years, several studies have closely investigated this solar wind - lunar surface interaction from various viewpoints. The main findings of these studies include (1) the dependency of the hydrogen reflection ratio on the local crustal magnetic fields (e.g., Wieser et al. [Geophys. Res. Lett. ,2010] and Vorburger et al. [J. Geophys. Res., 2012]), (2) the determination of the energy spectra of backscattered neutralized solar wind protons (Futaana et al. [J. Geophys. Res., 2012]) (3) the use of the spectra shape to remotely define an electric potential above a lunar magnetic anomaly (Futaana et al. [Geophys. Res. Lett., 2012]), (4) the favouring of backscattering over forward-scattering of impinging solar wind hydrogen particles (Vorburger et al. [Geophys. Res. Lett., 2011]), (5) the first-ever measurements of sputtered lunar oxygen (Vorburger et al. [J. Geophys. Res., 2012]), (6) the first-ever observation of backscattered solar wind helium (Vorburger et al. [J. Geophys. Res., 2012]), and (7) the determination of the scattering

  11. Far-IR detection of neutral atomic oxygen toward the Horsehead Nebula

    CERN Document Server

    Goicoechea, Javier R; Habart, Emilie

    2009-01-01

    We present the first detection of neutral atomic oxygen (3P_1-3P_2 fine structure line at ~63um) toward the Horsehead photodissociation region (PDR). The cloud has been mapped with the Spitzer Space Telescope at far-IR (FIR) wavelengths using MIPS in the Spectral Energy Distribution (SED) mode. The [OI]63um line peaks at the illuminated edge of the cloud at AV~0.1-0.5 (inwards the gas becomes too cold and outwards the gas density drops). The luminosity carried by the [OI]63um line represents a significant fraction of the total FIR dust luminosity (I_63/I_FIR~4x10^-3). We analyze the dust continuum emission and the nonlocal OI excitation and radiative transfer in detail. The observations are reproduced with a gas density of n_H~10^4 cm^-3 and gas and dust temperatures of T_k~100 K and T_d~30 K. We conclude that the determination of the OI 3P_J level populations and emergent line intensities at such ``low'' densities is a complex non-LTE problem. FIR radiative pumping, [OI]63um subthermal emission, [OI]145um su...

  12. BRAMA, a Broad Range Atomic Mass Analyzer for the ISL

    Energy Technology Data Exchange (ETDEWEB)

    Nitschke, J.M. [Lawrence Berkeley Lab., CA (United States)

    1994-05-01

    An alternative to conventional on-line isotope separators for use in radioactive beam facilities is described. It consists of an analyzer with a static magnetic field that is capable of separating a wide mixture of (radioactive) ions into mass bins ranging from 6 to 240 u. If incorporated into the ISL, BRAMA would make several low-energy radioactive beams available for experiments simultaneously, in addition to the beam that is being delivered to the post-accelerator. A preliminary ion-optical geometry is discussed.

  13. Cold neutral atoms via charge exchange from excited state positronium: a proposal

    CERN Document Server

    Bertsche, W A; Eriksson, S

    2016-01-01

    We present a method for generating cold neutral atoms via charge exchange reactions between trapped ions and Rydberg positronium. The high charge exchange reaction cross section leads to efficient neutralisation of the ions and since the positronium-ion mass ratio is small, the neutrals do not gain appreciable kinetic energy in the process. When the original ions are cold the reaction produces neutrals that can be trapped or further manipulated with electromagnetic fields. Because a wide range of species can be targeted we envisage that our scheme may enable experiments at low temperature that have been hitherto intractable due to a lack of cooling methods. We present an estimate for achievable temperatures, neutral number and density in an experiment where the neutrals are formed at a milli-Kelvin temperature from either directly or sympathetically cooled ions confined on an ion chip. The neutrals may then be confined by their magnetic moment in a co-located magnetic minimum well also formed on the chip. We ...

  14. Antihydrogen formation dynamics in a multipolar neutral anti-atom trap

    Science.gov (United States)

    Andresen, G. B.; Bertsche, W.; Bowe, P. D.; Bray, C.; Butler, E.; Cesar, C. L.; Chapman, S.; Charlton, M.; Fajans, J.; Fujiwara, M. C.; Gill, D. R.; Hangst, J. S.; Hardy, W. N.; Hayano, R. S.; Hayden, M. E.; Humphries, A. J.; Hydomako, R.; Jørgensen, L. V.; Kerrigan, S. J.; Kurchaninov, L.; Lambo, R.; Madsen, N.; Nolan, P.; Olchanski, K.; Olin, A.; Povilus, A.; Pusa, P.; Robicheaux, F.; Sarid, E.; El Nasr, S. Seif; Silveira, D. M.; Storey, J. W.; Thompson, R. I.; van der Werf, D. P.; Wurtele, J. S.; Yamazaki, Y.; Alpha Collaboration

    2010-03-01

    Antihydrogen production in a neutral atom trap formed by an octupole-based magnetic field minimum is demonstrated using field-ionization of weakly bound anti-atoms. Using our unique annihilation imaging detector, we correlate antihydrogen detection by imaging and by field-ionization for the first time. We further establish how field-ionization causes radial redistribution of the antiprotons during antihydrogen formation and use this effect for the first simultaneous measurements of strongly and weakly bound antihydrogen atoms. Distinguishing between these provides critical information needed in the process of optimizing for trappable antihydrogen. These observations are of crucial importance to the ultimate goal of performing CPT tests involving antihydrogen, which likely depends upon trapping the anti-atom.

  15. Antihydrogen formation dynamics in a multipolar neutral anti-atom trap

    CERN Document Server

    Andresen, G B; Bowe, P D; Bray, C; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Fujiwara, M C; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Humphries, A J; Hydomako, R; Jørgensen, L V; Kerrigan, S J; Kurchaninov, L; Lambo, R; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Seif El Nasr, S; Silveira, D M; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2010-01-01

    Antihydrogen production in a neutral atom trap formed by an octupole-based magnetic field minimum is demonstrated using field-ionization of weakly bound anti-atoms. Using our unique annihilation imaging detector, we correlate antihydrogen detection by imaging and by field-ionization for the first time. We further establish how field-ionization causes radial redistribution of the antiprotons during antihydrogen formation and use this effect for the first simultaneous measurements of strongly and weakly bound antihydrogen atoms. Distinguishing between these provides critical information needed in the process of optimizing for trappable antihydrogen. These observations are of crucial importance to the ultimate goal of performing CPT tests involving antihydrogen, which likely depends upon trapping the anti-atom.

  16. Tensorial depolarization of alkali atoms by isotropic collisions with neutral hydrogen

    CERN Document Server

    Derouich, Moncef

    2012-01-01

    Results. We consider the problem of isotropic collisions between an alkali atom and neutral hydrogen. We calculate the collisional tensorial components of general p and s-states, characterized by their effective principal quantum number $n^{*}$. It is found that the behaviour of the tensorial components obey simple power laws allowing quick calculations of the depolarizing collisional rates. As application, our results should allow a rigorous treatment of the atomic polarization profiles of the D1 -D2 lines of alkali atoms. Conclusions. Close coupling treatments of atomic collisions are needed to decipher the information encoded in the polarized radiation from the Sun. Important problems remain unresolved like the role of collisions in the Paschen-Back conditions.

  17. Empirical model for electron impact ionization cross sections of neutral atoms

    Energy Technology Data Exchange (ETDEWEB)

    Talukder, M.R.; Bose, S. [Rajshahi Univ., Dept. of Applied Physics and Electronic Engineering (Bangladesh); Patoary, M.A.R.; Haque, A.K.F.; Uddin, M.A.; Basak, A.K. [Rajshahi Univ., Dept. of Physics (Bangladesh); Kando, M. [Shizuoka Univ., Graduate School of Electronic Science and Technology (Japan)

    2008-02-15

    A simple empirical formula is proposed for the rapid calculation of electron impact total ionization cross sections both for the open- and closed-shell neutral atoms considered in the range 1 {<=} Z {<=} 92 and the incident electron energies from threshold to about 10{sup 4} eV. The results of the present analysis are compared with the available experimental and theoretical data. The proposed model provides a fast method for calculating fairly accurate electron impact total ionization cross sections of atoms. This model may be a prudent choice, for the practitioners in the field of applied sciences e.g. in plasma modeling, due to its simple inherent structure. (authors)

  18. Relativistic calculations of the non-resonant two-photon ionization of neutral atoms

    CERN Document Server

    Hofbrucker, Jiri; Fritzsche, Stephan

    2016-01-01

    The non-resonant two-photon one-electron ionization of neutral atoms is studied theoretically in the framework of relativistic second-order perturbation theory and independent particle approximation. In particular, the importance of relativistic and screening effects in the total two-photon ionization cross section is investigated. Detailed computations have been carried out for the K-shell ionization of neutral Ne, Ge, Xe, and U atoms. The relativistic effects significantly decrease the total cross section, for the case of U, for example, they reduce the total cross section by a factor of two. Moreover, we have found that the account for the screening effects of the remaining electrons leads to occurrence of an unexpected minimum in the total cross section at the total photon energies equal to the ionization threshold, for the case of Ne, for example, the cross section drops there by a factor of three.

  19. IMPACT OF PLANETARY GRAVITATION ON HIGH-PRECISION NEUTRAL ATOM MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Kucharek, H.; Möbius, E.; Lee, M. A.; Park, J.; Schwadron, N. A [University of New Hampshire, 8 College Road, Durham, NH, 03824 (United States); Galli, A.; Wurz, P. [Physikalisches Institut der Universität Bern, Bern (Switzerland); Fuselier, S. A.; McComas, D. [Southwest Research Institute, San Antonio, TX (United States); Bzowski, M. [Space Research Centre, Polish Academy of Sciences, Warsaw (Poland)

    2015-10-15

    Measurements of energetic neutral atoms (ENAs) have been extremely successful in providing very important information on the physical processes inside and outside of our heliosphere. For instance, recent Interstellar Boundary Explorer (IBEX) observations have provided new insights into the local interstellar environment and improved measurements of the interstellar He temperature, velocity, and direction of the interstellar flow vector. Since particle collisions are rare, and radiation pressure is negligible for these neutrals, gravitational forces mainly determine the trajectories of neutral He atoms. Depending on the distance of an ENA to the source of a gravitational field and its relative speed and direction, this can result in significant deflection and acceleration. In this paper, we investigate the impact of the gravitational effects of Earth, the Moon, and Jupiter on ENA measurements performed in Earth’s orbit. The results show that current analysis of the interstellar neutral parameters by IBEX is not significantly affected by planetary gravitational effects. We further studied the possibility of whether or not the Helium focusing cone of the Sun and Jupiter could be measured by IBEX and whether or not these cones could be used as an independent measure of the temperature of interstellar Helium.

  20. Potential merits for substorm research from imaging of charge-exchange neutral atoms

    Directory of Open Access Journals (Sweden)

    I. A. Daglis

    Full Text Available The in situ observations of the Earth magnetosphere performed over the past decades of space research have provided a rather good understanding of many partial localized processes of the magnetospheric substorm. The continuing lack of global observations inhibits the construction of a coherent picture of the substorm as a whole, which is actually determined by the coupling of the partial processes. In this context the importance of global observations for the advancement of magnetospheric substorm studies is critical. This paper presents briefly a promising technique of global observations, namely the imaging of charge exchange neutral atoms, or neutral atom imaging (NAI of the magnetosphere. Model and theoretical estimates of charge-exchange neutral atom fluxes, as well as appropriate spacecraft orbit and instrumentation requirements are presented and discussed for specific regions of interest and vantage points. The potential merits of NAI for substorm research are presented along with possible combinations with other types of observational methods. Substorm issues that would benefit from NAI should include among others the assessment of the ionospheric contribution to the hot magnetospheric plasma, the relative importance of various ionospheric ion source regions, the resolution of spatial and temporal characteristics of substorm ion injections. NAI observations can be precious complements to local observations and lead to the understanding of how local processes, many of which are resolved quite well today, combine to form the global process of the magnetospheric substorm.

  1. Precipitation of energetic neutral atoms and induced non-thermal escape fluxes from the Martian atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Lewkow, N. R.; Kharchenko, V. [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States)

    2014-08-01

    The precipitation of energetic neutral atoms, produced through charge exchange collisions between solar wind ions and thermal atmospheric gases, is investigated for the Martian atmosphere. Connections between parameters of precipitating fast ions and resulting escape fluxes, altitude-dependent energy distributions of fast atoms and their coefficients of reflection from the Mars atmosphere, are established using accurate cross sections in Monte Carlo (MC) simulations. Distributions of secondary hot (SH) atoms and molecules, induced by precipitating particles, have been obtained and applied for computations of the non-thermal escape fluxes. A new collisional database on accurate energy-angular-dependent cross sections, required for description of the energy-momentum transfer in collisions of precipitating particles and production of non-thermal atmospheric atoms and molecules, is reported with analytic fitting equations. Three-dimensional MC simulations with accurate energy-angular-dependent cross sections have been carried out to track large ensembles of energetic atoms in a time-dependent manner as they propagate into the Martian atmosphere and transfer their energy to the ambient atoms and molecules. Results of the MC simulations on the energy-deposition altitude profiles, reflection coefficients, and time-dependent atmospheric heating, obtained for the isotropic hard sphere and anisotropic quantum cross sections, are compared. Atmospheric heating rates, thermalization depths, altitude profiles of production rates, energy distributions of SH atoms and molecules, and induced escape fluxes have been determined.

  2. An apparatus for immersing trapped ions into an ultracold gas of neutral atoms.

    Science.gov (United States)

    Schmid, Stefan; Härter, Arne; Frisch, Albert; Hoinka, Sascha; Denschlag, Johannes Hecker

    2012-05-01

    We describe a hybrid vacuum system in which a single ion or a well-defined small number of trapped ions (in our case Ba(+) or Rb(+)) can be immersed into a cloud of ultracold neutral atoms (in our case Rb). This apparatus allows for the study of collisions and interactions between atoms and ions in the ultracold regime. Our setup is a combination of a Bose-Einstein condensation apparatus and a linear Paul trap. The main design feature of the apparatus is to first separate the production locations for the ion and the ultracold atoms and then to bring the two species together. This scheme has advantages in terms of stability and available access to the region where the atom-ion collision experiments are carried out. The ion and the atoms are brought together using a moving one-dimensional optical lattice transport which vertically lifts the atomic sample over a distance of 30 cm from its production chamber into the center of the Paul trap in another chamber. We present techniques to detect and control the relative position between the ion and the atom cloud.

  3. Two Wide-Angle Imaging Neutral-Atom Spectrometers and Interstellar Boundary Explorer energetic neutral atom imaging of the 5 April 2010 substorm

    Science.gov (United States)

    McComas, D. J.; Buzulukova, N.; Connors, M. G.; Dayeh, M. A.; Goldstein, J.; Funsten, H. O.; Fuselier, S.; Schwadron, N. A.; Valek, P.

    2012-03-01

    This study is the first to combine energetic neutral atom (ENA) observations from Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS) and Interstellar Boundary Explorer (IBEX). Here we examine the arrival of an interplanetary shock and the subsequent geomagnetically effective substorm on 5 April 2010, which was associated with the Galaxy 15 communications satellite anomaly. IBEX shows sharply enhanced ENA emissions immediately upon compression of the dayside magnetosphere at 08:26:17+/-9 s UT. The compression drove a markedly different spectral shape for the dayside emissions, with a strong enhancement at energies >1 keV, which persisted for hours after the shock arrival, consistent with the higher solar wind speed, density, and dynamic pressure (˜10 nPa) after the shock. TWINS ENA observations indicate a slower response of the ring current and precipitation of ring current ions as low-altitude emissions ˜15 min later, with the >50 keV ion precipitation leading the internal magnetospheric processes are occurring after compression of the magnetosphere and before the ring current ions end up in the loss cone and precipitate into the ionosphere. We also compare MHD simulation results with both the TWINS and IBEX ENA observations; while the overall fluxes and distributions of emissions were generally similar, there were significant quantitative differences. Such differences emphasize the complexity of the magnetospheric system and importance of the global perspective for macroscopic magnetospheric studies. Finally, Appendix A documents important details of the TWINS data processing, including improved binning procedures, smoothing of images to a given level of statistical accuracy, and differential background subtraction.

  4. Creation of effective magnetic fields in optical lattices The Hofstadter butterfly for cold neutral atoms

    CERN Document Server

    Jaksch, D

    2003-01-01

    We investigate the dynamics of neutral atoms in a 2D optical lattice which traps two distinct internal states of the atoms in different columns. Two Raman lasers are used to coherently transfer atoms from one internal state to the other, thereby causing hopping between the different columns. By adjusting the laser parameters appropriately we can induce a non vanishing phase of particles moving along a closed path on the lattice. This phase is proportional to the enclosed area and we thus simulate a magnetic flux through the lattice. This setup is described by a Hamiltonian identical to the one for electrons on a lattice subject to a magnetic field and thus allows us to study this equivalent situation under very well defined controllable conditions. We consider the limiting case of huge magnetic fields -- which is not experimentally accessible for electrons in metals -- where a fractal band structure, the Hofstadter butterfly, characterizes the system.

  5. Precipitation of Energetic Neutral Atoms and Induced Non-Thermal Escape Fluxes from the Martian Atmosphere

    CERN Document Server

    Lewkow, Nicholas

    2014-01-01

    The precipitation of energetic neutral atoms (ENAs), produced through charge exchange (CX) collisions between solar wind (SW) ions and thermal atmospheric gases, is investigated. Subsequent induced non-thermal escape fluxes have been carried out for the Martian atmosphere. Detailed modeling of the ENA energy input and determination of connections between parameters of precipitating ENAs and resulting escape fluxes, reflection coefficients of fast atoms from the Mars atmosphere, and altitude dependent ENA energy distributions are established using Monte Carlo (MC) simulations of the precipitation process with accurate quantum mechanical (QM) cross sections. Detailed descriptions of secondary hot (SH) atoms and molecules induced by ENAs have been obtained for a better understanding of the mechanisms responsible for atmospheric escape and evolution. The effects of using isotropic hard sphere (HS) cross sections as compared to realistic, anisotropic quantum cross sections are examined for energy-deposition profil...

  6. Coherence preservation of a single neutral atom qubit transferred between magic-intensity optical traps

    CERN Document Server

    Yang, Jiaheng; Guo, Ruijun; Xu, Peng; Wang, Kunpeng; Sheng, Cheng; Liu, Min; Wang, Jin; Derevianko, Andrei; Zhan, Mingsheng

    2016-01-01

    We demonstrate that the coherence of a single mobile atomic qubit can be well preserved during a transfer process among different optical dipole traps (ODTs). This is a prerequisite step in realizing a large-scale neutral atom quantum information processing platform. A qubit encoded in the hyperfine manifold of $^{87}$Rb atom is dynamically extracted from the static quantum register by an auxiliary moving ODT and reinserted into the static ODT. Previous experiments were limited by decoherences induced by the differential light shifts of qubit states. Here we apply a magic-intensity trapping technique which mitigates the detrimental effects of light shifts and substantially enhances the coherence time to $225 \\pm 21\\,\\mathrm{ms}$. The experimentally demonstrated magic trapping technique relies on the previously neglected hyperpolarizability contribution to the light shifts, which makes the light shift dependence on the trapping laser intensity to be parabolic. Because of the parabolic dependence, at a certain ...

  7. Analyzing new neutral gauge bosons at the LHC using third generation fermions

    CERN Document Server

    Martin, Travis A W

    2007-01-01

    This thesis reports on techniques and the corresponding phenomenology for distinguishing between models in the analysis of new neutral gauge boson production at the LHC. Specifically, third generation final states are reviewed and determined to be effective channels for analysis. Transverse momentum cuts of pxf > 0.3 Mz> to hadronic final states are employed to reduce QCD backgrounds and distinguish t and b signals. An analysis of the ratio of the t and b cross sections to the fi cross section, within an invariant mass window of 0.965 Mz> , is performed. For final state fermion detection efficiencies of = 0.96, et = 0.10, and e*, = 0.50, most models considered can be distinguished by at least one standard deviation for Mz> = 1500 GeV, with 10 fb_1 integrated luminosity. Furthermore, the ratio of the t to cross sections is analyzed and used to understand models with preferential couplings to third generation particles in the lepton family. Assuming an efficiency of er = 0.2, generation universality can be dete...

  8. ELENA MCP detector: absolute detection efficiency for low-energy neutral atoms

    Science.gov (United States)

    Rispoli, R.; De Angelis, E.; Colasanti, L.; Vertolli, N.; Orsini, S.; Scheer, J. A.; Mura, A.; Milillo, A.; Wurz, P.; Selci, S.; Di Lellis, A. M.; Leoni, R.; D'Alessandro, M.; Mattioli, F.; Cibella, S.

    2012-09-01

    Microchannel Plates (MCP) detectors are frequently used in space instrumentation for detecting a wide range of radiation and particles. In particular, the capability to detect non-thermal low energy neutral species is crucial for the sensor ELENA (Emitted Low-Energy Neutral Atoms), part of the package SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) on board the BepiColombo mission of ESA to Mercury to be launched in 2015. ELENA is a Time of Flight (TOF) sensor, based on a novel concept using an ultra-sonic oscillating shutter (Start section), which is operated at frequencies up to 50 kHz; a MCP detector is used as a Stop detector. The scientific objective of ELENA is to detect energetic neutral atoms in the range 10 eV - 5 keV, within 76° FOV, perpendicular to the S/C orbital plane. ELENA will monitor the emission of neutral atoms from the whole surface of Mercury thanks to the spacecraft motion. The major scientific objectives are the interaction between the plasma environment and the planet’s surface, the global particle loss-rate and the remote sensing of the surface properties. In particular, surface release processes are investigated by identifying particles released from the surface, via solar wind-induced ion sputtering (MEFISTO facility of the Physical Institute of the University of Bern (CH), measurements on three different types of MCP (with and without coating) have been performed providing the detection efficiencies in the energy range 10eV - 1keV. Outcomes from such measurements are discussed here.

  9. Relativistic calculations of screening parameters and atomic radii of neutral atoms

    Science.gov (United States)

    Guerra, M.; Amaro, P.; Santos, J. P.; Indelicato, P.

    2017-09-01

    Calculations of the effective nuclear charge for elements with 1 ≤ Z ≤ 118 have been performed in a Dirac-Fock approach including all relativistic effects as well as contributions from quantum electrodynamics. Maximum charge density for every subshell of every element in the periodic table was also computed in the same framework as well as atomic radii based on the total charge density. Results were compared with the extensively cited works of Clementi et al., obtained in the 1960s with Roothan's self-consistent-field method.

  10. Measurement of the parity nonconserving neutral weak interaction in atomic thallium

    Energy Technology Data Exchange (ETDEWEB)

    Bucksbaum, P.H.

    1980-11-01

    This thesis describes an experiment to measure parity nonconservation in atomic thallium. A frequency doubled, flashlamp pumped tunable dye laser is used to excite the 6P/sub 1/2/(F = 0) ..-->.. 7P/sub 1/2/(F = 1) transition at 292.7 nm, with circularly polarized light. An electrostatic field E of 100 to 300 V/cm causes this transition to occur via Stark induced electric dipole. Two field free transitions may also occur: a highly forbidden magnetic dipole M, and a parity nonconserving electric dipole epsilon/sub P/. The latter is presumed to be due to the presence of a weak neutral current interaction between the 6p valence electron and the nucleus, as predicted by gauge theories which unite the electromagnetic and weak interactions. Both M and epsilon/sub P/ interfere with the Stark amplitude ..beta..E to produce a polarization of the 7P/sub 1/2/ state. This is measured with a circularly polarized infrared laser beam probe, tuned to the 7P/sub 1/2/ ..-->.. 8S/sub 1/2/ transition. This selectively excites m/sub F/ = +1 or -1 components of the 7P/sub 1/2/ state, and the polarization is seen as an asymmetry in 8S ..-->.. 6P/sub 3/2/ fluorescence when the probe helicity is reversed. The polarization due to M is ..delta../sub M/ = -2M/(BETAE). It is used to calibrate the analyzing efficiency. The polarization due to epsilon/sub P/ is ..delta../sub P/ = 2i epsilon/sub P//(..beta..E), and can be distinguished from ..delta../sub M/ by its properties under reversal of the 292.7 nm photon helicity and reversal of the laser direction. A preliminary measurement yielded a parity violation in agreement with the gauge theory of Weinberg and Salam.

  11. Remote Sensing of Icy Galilean Moon Surface and Atmospheric Composition Using Low Energy (1 eV-4 keV) Neutral Atom Imaging

    Science.gov (United States)

    Collier, M. R.; Sittler, E.; Chornay, D.; Cooper, J. F.; Coplan, M.; Johnson, R. E.

    2004-01-01

    We describe a low energy neutral atom imager suitable for composition measurements Europa and other icy Galilean moons in the Jovian magnetosphere. This instrument employs conversion surface technology and is sensitive to either neutrals converted to negative ions, neutrals converted to positive ions and the positive ions themselves depending on the power supply. On a mission such as the Jupiter Icy Moons Orbiter (JIMO), two back-to-back sensors would be flown with separate power supplies fitted to the neutral atom and iodneutral atom sides. This will allow both remote imaging of 1 eV atmospheres, and in situ measurements of ions at similar energies in the moon ionospheres and Jovian magnetospheric plasma. The instrument provides composition measurements of the neutrals and ions that enter the spectrometer with a mass resolution dependent on the time-of-flight subsystem and capable of resolving molecules. The lower energy neutrals, up to tens of eV, arise from atoms and molecules sputtered off the moon surfaces and out of the moon atmospheres by impacts of more energetic (keV to MeV) ions from the magnetosphere. Direct Simulation Monte Carlo (DSMC) models are used to convert measured neutral abundances to compositional distributions of primary and trace species in the sputtered surfaces and atmospheres. The escaping neutrals can also be detected as ions after photo- or plasma-ionization and pickup. Higher energy, keV neutrals come from charge exchange of magnetospheric ions in the moon atmospheres and provide information on atmospheric structure. At the jovicentric orbits of the icy moons the presence of toroidal gas clouds, as detected at Europa's orbit, provide M e r opportunities to analyze both the composition of neutrals and ions originating from the moon surfaces, and the characteristics of magnetospheric ions interacting with neutral cloud material. Charge exchange of low energy ions near the moons, and directional distributions of the resultant neutrals

  12. Analyzing quantum jumps of one and two atoms strongly coupled to an optical cavity

    DEFF Research Database (Denmark)

    Reick, Sebastian; Mølmer, Klaus; Alt, Wolfgang;

    2010-01-01

    We induce quantum jumps between the hyperfine ground states of one and two cesium atoms, strongly coupled to the mode of a high-finesse optical resonator, and analyze the resulting random telegraph signals. We identify experimental parameters to deduce the atomic spin state nondestructively from ...

  13. Investigating Pickup Ions with New Horizons, Ulysses and Voyager and Their Diagnostics By Fluxes of Energetic Neutral Atoms

    Science.gov (United States)

    Wu, Y.; Florinski, V. A.

    2014-12-01

    Pickup ions (PUIs) play a major role in the solar wind (SW) interaction with the local inter-stellar medium (LISM). An understanding of the transport of PUIs in the heliosphere is important.Here, we solve the transport equation to examine the detailed spatial evolution of the PUI distri-bution in supersonic solar wind. The effects of second-order Fermi process, i.e. velocity diffusion,convection with the solar wind, adiabatic cooling and continual injection of newly born PUIs areall included. We analyze the transition of PUIs at the heliospheric termination shock (TS) anddescribe the heliosheath PUI distribution taking into account ongoing velocity diffusion. A three-dimensional, MHD-kinetic model for flows of a thermal plasma, neutral atoms and PUIs has beendeveloped. The flow of the plasma is modeled using solutions to MHD equations. The PUI transportmodule analyzes the spatial variation of the PUI distribution function as a separate component, ona kinetic level. We perform a comparison of our numerical results with observations made by NewHorizons, Ulysses and Voyager. Fluxes of energetic neutral atoms (ENA) with energies of about0.2-6 keV originating through charge exchange of H atoms with the compressed solar wind andwith PUIs behind the TS and arriving at 1 AU are calculated. Our results are directly comparablewith the actual IBEX distributed ENA sky maps. A comparison of our numerical results withmeasurements performed by IBEX will allow us to answer the challenging question: how the PUIdistribution affects the ENA fluxes from the heliosheath?

  14. Low-Entropy States of Neutral Atoms in Polarization-Synthesized Optical Lattices.

    Science.gov (United States)

    Robens, Carsten; Zopes, Jonathan; Alt, Wolfgang; Brakhane, Stefan; Meschede, Dieter; Alberti, Andrea

    2017-02-10

    We create low-entropy states of neutral atoms by utilizing a conceptually new optical-lattice technique that relies on a high-precision, high-bandwidth synthesis of light polarization. Polarization-synthesized optical lattices provide two fully controllable optical lattice potentials, each of them confining only atoms in either one of the two long-lived hyperfine states. By employing one lattice as the storage register and the other one as the shift register, we provide a proof of concept using four atoms that selected regions of the periodic potential can be filled with one particle per site. We expect that our results can be scaled up to thousands of atoms by employing an atom-sorting algorithm with logarithmic complexity, which is enabled by polarization-synthesized optical lattices. Vibrational entropy is subsequently removed by sideband cooling methods. Our results pave the way for a bottom-up approach to creating ultralow-entropy states of a many-body system.

  15. Generation of neutral atomic beams utilizing photodetachment by high power diode laser stacks

    Science.gov (United States)

    O'Connor, A. P.; Grussie, F.; Bruhns, H.; de Ruette, N.; Koenning, T. P.; Miller, K. A.; Savin, D. W.; Stützel, J.; Urbain, X.; Kreckel, H.

    2015-11-01

    We demonstrate the use of high power diode laser stacks to photodetach fast hydrogen and carbon anions and produce ground term neutral atomic beams. We achieve photodetachment efficiencies of ˜7.4% for H- at a beam energy of 10 keV and ˜3.7% for C- at 28 keV. The diode laser systems used here operate at 975 nm and 808 nm, respectively, and provide high continuous power levels of up to 2 kW, without the need of additional enhancements like optical cavities. The alignment of the beams is straightforward and operation at constant power levels is very stable, while maintenance is minimal. We present a dedicated photodetachment setup that is suitable to efficiently neutralize the majority of stable negative ions in the periodic table.

  16. Generation of neutral atomic beams utilizing photodetachment by high power diode laser stacks

    CERN Document Server

    O'Connor, A P; Grussie, F; Koenning, T P; Miller, K A; de Ruette, N; Stützel, J; Savin, D W; Urbain, X; Kreckel, H

    2015-01-01

    We demonstrate the use of high power diode laser stacks to photodetach fast hydrogen and carbon anions and produce ground term neutral atomic beams. We achieve photodetachment efficiencies of $\\sim$7.4\\% for H$^-$ at a beam energy of 10\\,keV and $\\sim$3.7\\% for C$^-$ at 28\\,keV. The diode laser systems used here operate at 975\\,nm and 808\\,nm, respectively, and provide high continuous power levels of up to 2\\,kW, without the need of additional enhancements like optical cavities. The alignment of the beams is straightforward and operation at constant power levels is very stable, while maintenance is minimal. We present a dedicated photodetachment setup that is suitable to efficiently neutralize the majority of stable negative ions in the periodic table.

  17. Measurement of visible and UV emission from Energetic Neutral Atom Precipitation (ENAP), on Spacelab

    Science.gov (United States)

    Tinsley, B. A.

    1980-01-01

    The charge exchange of plasmaspheric ions and exospheric H and O and of solar wind ions with exospheric and interplanetary H are sources of precipitating neutrals whose faint emission may be observed by the imaging spectrometric observatory during dark periods of the SL-1 orbit. Measurements of the interactions of these precipitating atoms with the thermosphere are needed to evaluate the heating and ionization effects on the atmosphere as well as the selective loss of i energetic ions from the sources (predominantly the ring current).

  18. Neutral atomic absorption lines and far-UV extinction: Possible implications for depletions and grain parameters

    Science.gov (United States)

    Welty, Daniel E.

    1990-01-01

    Researchers examine nine lines of sight within the Galaxy and one in the Large Magellanic Cloud (LMC) for which data on both neutral atomic absorption lines (Snow 1984; White 1986; Welty, Hobbs, and York 1989) and far UV extinction (Bless and Savage 1972; Jenkins, Savage, and Spitzer 1986) are available, in order to test the assumption that variations in gamma/alpha will cancel in taking ratios of the ionization balance equation, and to try to determine to what extent that assumption has affected the aforementioned studies of depletions and grain properties.

  19. Neutral oxygen atom density in the MESOX air plasma solar furnace facility

    Science.gov (United States)

    Balat-Pichelin, Marianne; Vesel, Alenka

    2006-08-01

    The density of neutral oxygen atoms in the MESOX set-up, one device of the PROMES-CNRS solar facilities, was determined by a fiber-optics catalytic probe (FOCP). Plasma was created in a flowing air within a quartz tube with the outer diameter of 5 cm by a 2.45 GHz microwave generator with the output power up to 1000 W. The flow of air was varied between 4 and 20 l/h. The O-atom density was found to increase monotonously with the increasing discharge power, and it decreased with the increasing flow rate. The degree of dissociation of oxygen molecules in the plasma column depended largely on the flow rate. At the air flow of 4 l/h it was about 80% but it decreased to about 20% at the flow of 20 l/h.

  20. Neutral oxygen atom density in the MESOX air plasma solar furnace facility

    Energy Technology Data Exchange (ETDEWEB)

    Balat-Pichelin, Marianne [CNRS-PROMES, Laboratoire Procedes, Materiaux et Energie Solaire, UPR 8521, 7 rue du four solaire, F-66120 Font Romeu, Odeillo (France)], E-mail: balat@promes.cnrs.fr; Vesel, Alenka [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)

    2006-08-21

    The density of neutral oxygen atoms in the MESOX set-up, one device of the PROMES-CNRS solar facilities, was determined by a fiber-optics catalytic probe (FOCP). Plasma was created in a flowing air within a quartz tube with the outer diameter of 5 cm by a 2.45 GHz microwave generator with the output power up to 1000 W. The flow of air was varied between 4 and 20 l/h. The O-atom density was found to increase monotonously with the increasing discharge power, and it decreased with the increasing flow rate. The degree of dissociation of oxygen molecules in the plasma column depended largely on the flow rate. At the air flow of 4 l/h it was about 80% but it decreased to about 20% at the flow of 20 l/h.

  1. Developing Density of Laser-Cooled Neutral Atoms and Molecules in a Linear Magnetic Trap

    Science.gov (United States)

    Velasquez, Joe, III; Walstrom, Peter; di Rosa, Michael

    2013-05-01

    In this poster we show that neutral particle injection and accumulation using laser-induced spin flips may be used to form dense ensembles of ultracold magnetic particles, i.e., laser-cooled paramagnetic atoms and molecules. Particles are injected in a field-seeking state, are switched by optical pumping to a field-repelled state, and are stored in the minimum-B trap. The analogous process in high-energy charged-particle accumulator rings is charge-exchange injection using stripper foils. The trap is a linear array of sextupoles capped by solenoids. Particle-tracking calculations and design of our linear accumulator along with related experiments involving 7Li will be presented. We test these concepts first with atoms in preparation for later work with selected molecules. Finally, we present our preliminary results with CaH, our candidate molecule for laser cooling. This project is funded by the LDRD program of Los Alamos National Laboratory.

  2. Analyzing Ferroresonance Phenomena in Power Transformers Including Zinc Oxide Arrester and Neutral Resistance Effect

    Directory of Open Access Journals (Sweden)

    Hamid Radmanesh

    2012-01-01

    Full Text Available This paper studies the effect of zinc oxide arrester (ZnO and neutral earth resistance on controlling nonconventional oscillations of the unloaded power transformer. At first, ferroresonance overvoltage in the power system including ZnO is investigated. It is shown this nonlinear resistance can limit the ferroresonance oscillations but it cannot successfully control these phenomena. Because of the temperature dissipation of ZnO, it can withstand against overvoltage in a short period and after that ferroresonance causes ZnO failure. By applying neutral earth resistance to the system configuration, mitigating ferroresonance has been increased and chaotic overvoltage has been changed to the smoother behavior such as fundamental resonance and periodic oscillation. The simulation results show that connecting the neutral resistance exhibits a great mitigating effect on nonlinear overvoltage.

  3. Determination of the neutral oxygen atom density in a plasma reactor loaded with metal samples

    Energy Technology Data Exchange (ETDEWEB)

    Mozetic, Miran; Cvelbar, Uros [Jozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia)], E-mail: miran.mozetic@ijs.si

    2009-08-15

    The density of neutral oxygen atoms was determined during processing of metal samples in a plasma reactor. The reactor was a Pyrex tube with an inner diameter of 11 cm and a length of 30 cm. Plasma was created by an inductively coupled radiofrequency generator operating at a frequency of 27.12 MHz and output power up to 500 W. The O density was measured at the edge of the glass tube with a copper fiber optics catalytic probe. The O atom density in the empty tube depended on pressure and was between 4 and 7 x 10{sup 21} m{sup -3}. The maximum O density was at a pressure of about 150 Pa, while the dissociation fraction of O{sub 2} molecules was maximal at the lowest pressure and decreased with increasing pressure. At about 300 Pa it dropped below 10%. The measurements were repeated in the chamber loaded with different metallic samples. In these cases, the density of oxygen atoms was lower than that in the empty chamber. The results were explained by a drain of O atoms caused by heterogeneous recombination on the samples.

  4. Time-resolved ion energy distribution measurements using an advanced neutral particle analyzer on the MST reversed-field pinch.

    Science.gov (United States)

    Eilerman, S; Anderson, J K; Reusch, J A; Liu, D; Fiksel, G; Polosatkin, S; Belykh, V

    2012-10-01

    An advanced neutral particle analyzer (ANPA) capable of simultaneously measuring hydrogen and deuterium ions of energies up to 45 keV has recently been developed for use on the Madison Symmetric Torus. The charge-to-mass separation allows for separate analysis of bulk deuterium ions and hydrogen ions injected with a 1 MW, 25 keV neutral beam. Orientation of the ANPA allows sampling of different regions of ion velocity space; a radial viewport favors collection of ions with high v(perpendicular)∕|v| while a recently installed tangential viewport favors ions with high v(||)∕|v|, such as those from the core-localized fast ion population created by the neutral beam. Signals are observed in the ANPA's highest energy channels during periodic magnetic reconnection events, which are drivers of anisotropic, non-Maxwellian ion energization in the reversed-field pinch. ANPA signal strength is dependent on the background neutral density, which also increases during magnetic reconnection events, so careful analysis must be performed to identify the true change in the ion distribution. A Monte Carlo neutral particle tracing code (NENE) is used to reconstruct neutral density profiles based on D(α) line emission, which is measured using a 16-chord filtered photodiode array.

  5. Ion heating during geomagnetic storms measured using energetic neutral atom imaging

    Science.gov (United States)

    Keesee, Amy; Elfritz, Justin; Katus, Roxanne; Scime, Earl

    2015-11-01

    Energy from the solar wind is deposited into the magnetosphere during geomagnetic storms. Much of this energy is deposited into the plasma sheet, driving phenomena that leads to heating. The plasma sheet ions are then injected to the inner magnetosphere, driving the ring current. While ions can undergo adiabatic heating during typical drift motion, collisional and wave-particle interactions can also lead to ion heating. A technique to measure ion temperatures using energetic neutral atom (ENA) data has been developed using ENA data from the Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) mission global maps of ion temperature during the evolution of geomagnetic storms are made. These maps exhibit the location and characteristics of regions of ion heating and during which storm phase they occur. Superposed epoch analyses of such maps have demonstrated typical characteristics of ion heating during storms driven by coronal mass ejections as compared to those driven by high speed solar wind streams. The temperatures have been used to establish boundary conditions for modeling of the inner magnetosphere. We will give an overview of recent studies using TWINS ion temperature maps. Work supported by NNX10AN08A and AGS-1113478.

  6. Assessment of energetic neutral He atom intensities expected from the IBEX Ribbon

    CERN Document Server

    Swaczyna, P; Bzowski, M

    2014-01-01

    Full sky maps of energetic neutral atoms (ENA) obtained with the Interstellar Boundary Explorer revealed a bright, arc-like Ribbon. We compare possible, thought as yet undetected, He ENA emission in two models of the Ribbon origin. The models were originally developed for hydrogen ENA. In the first one, ENA are produced outside the heliopause from the ionized neutral solar wind in the direction where the local interstellar magnetic field is perpendicular to the line-of-sight. The second model proposes production at the interface between the Local Interstellar Cloud (LIC) and the Local Bubble (LB). The models are redesigned to helium using relevant interactions between atoms and ions. Resulting intensities are compared with possible emission of helium ENA from the heliosheath. In the first model, expected intensity is ~ 0.014 (cm^2 s sr keV)^-1, i.e., of the order of the He emission from the heliosheath, whereas in the second, the LIC/LB interface model, the intensity is ~ (2 - 7) (cm^2 s sr keV)^-1, i.e., a f...

  7. Observations and Interpretations of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Event

    Science.gov (United States)

    Mewaldt, R. A.; Leske, R. A.; Shih, A. Y.; Stone, E. C.; Barghouty, A. f.; Cohen, C. M. S.; Cummings, A. c.; Labrador, A. W.; vonRosenvinge, T. T.

    2009-01-01

    We discuss recently reported observations of energetic neutral hydrogen atoms (ENAs) from an X9 solar flare/coronal mass ejection event on 5 December 2006, located at E79. The observations were made by the Low Energy Telescopes (LETs) on STEREO A and B. Prior to the arrival of the main solar energetic particle (SEP) event at Earth, both LETs observed a sudden burst of 1.6 to 15 MeV energetic neutral hydrogen atoms produced by either flare or shock-accelerated protons. RHESSI measurements of the 2.2-MeV gamma-ray line provide an estimate of the number of interacting flare-accelerated protons in this event, which leads to an improved estimate of ENA production by flare-accelerated protons. Taking into account ENA losses, we find that the observed ENAs must have been produced in the high corona at heliocentric distances > or equal to 2 solar radii. Although there are no CME images from this event, it is shown that CME-shock-accelerated protons can, in principle, produce a time-history consistent with the observations.

  8. STEREO Observations of Energetic Neutral Hydrogen Atoms during the 5 December 2006 Solar Flare

    Science.gov (United States)

    Mewaldt, R. A.; Leske, R. A.; Stone, E. C.; Barghouty, A. F.; Labrador, A. W.; Cohen, C. M. S.; Cummings, A. C.; Davis, A. J.; vonRosenvinge, T. T.; Wiedenbeck, M. E.

    2009-01-01

    We report the discovery of energetic neutral hydrogen atoms emitted during the X9 solar event of December 5, 2006. Beginning 1 hour following the onset of this E79 flare, the Low Energy Telescopes (LETs) on both the STEREO A and B spacecraft observed a sudden burst of 1.6 to 15 MeV protons beginning hours before the onset of the main solar energetic particle (SEP) event at Earth. More than 70% of these particles arrived from a longitude within 10 of the Sun, consistent with the measurement resolution. The derived emission profile at the Sun had onset and peak times remarkably similar to the GOES soft X-ray profile and continued for more than an hour. The observed arrival directions and energy spectrum argue strongly that the particle events less than 5 MeV were due to energetic neutral hydrogen atoms (ENAs). To our knowledge, this is the first reported observation of ENA emission from a solar flare/coronal mass ejection. Possible origins for the production of ENAs in a large solar event are considered. We conclude that the observed ENAs were most likely produced in the high corona and that charge-transfer reactions between accelerated protons and partially-stripped coronal ions are an important source of ENAs in solar events.

  9. Emission of hydrogen energetic neutral atoms from the Martian subsolar magnetosheath

    Science.gov (United States)

    Wang, X.-D.; Alho, M.; Jarvinen, R.; Kallio, E.; Barabash, S.; Futaana, Y.

    2016-01-01

    We have simulated the hydrogen energetic neutral atom (ENA) emissions from the subsolar magnetosheath of Mars using a hybrid model of the proton plasma charge exchanging with the Martian exosphere to study statistical features revealed from the observations of the Neutral Particle Detectors on Mars Express. The simulations reproduce well the observed enhancement of the hydrogen ENA emissions from the dayside magnetosheath in directions perpendicular to the Sun-Mars line. Our results show that the neutralized protons from the shocked solar wind are the dominant ENA population rather than those originating from the pickup planetary ions. The simulation also suggests that the observed stronger ENA emissions in the direction opposite to the solar wind convective electric field result from a stronger proton flux in the same direction at the lower magnetosheath; i.e., the proton fluxes in the magnetosheath are not cylindrically symmetric. We also confirm the observed increasing of the ENA fluxes with the solar wind dynamical pressure in the simulations. This feature is associated with a low altitude of the induced magnetic boundary when the dynamic pressure is high and the magnetosheath protons can reach to a denser exosphere, and thus, the charge exchange rate becomes higher. Overall, the analysis suggests that kinetic effects play an important and pronounced role in the morphology of the hydrogen ENA distribution and the plasma environment at Mars, in general.

  10. Near-Atomic Resolution Structure of a Highly Neutralizing Fab Bound to Canine Parvovirus.

    Science.gov (United States)

    Organtini, Lindsey J; Lee, Hyunwook; Iketani, Sho; Huang, Kai; Ashley, Robert E; Makhov, Alexander M; Conway, James F; Parrish, Colin R; Hafenstein, Susan

    2016-11-01

    Canine parvovirus (CPV) is a highly contagious pathogen that causes severe disease in dogs and wildlife. Previously, a panel of neutralizing monoclonal antibodies (MAb) raised against CPV was characterized. An antibody fragment (Fab) of MAb E was found to neutralize the virus at low molar ratios. Using recent advances in cryo-electron microscopy (cryo-EM), we determined the structure of CPV in complex with Fab E to 4.1 Å resolution, which allowed de novo building of the Fab structure. The footprint identified was significantly different from the footprint obtained previously from models fitted into lower-resolution maps. Using single-chain variable fragments, we tested antibody residues that control capsid binding. The near-atomic structure also revealed that Fab binding had caused capsid destabilization in regions containing key residues conferring receptor binding and tropism, which suggests a mechanism for efficient virus neutralization by antibody. Furthermore, a general technical approach to solving the structures of small molecules is demonstrated, as binding the Fab to the capsid allowed us to determine the 50-kDa Fab structure by cryo-EM.

  11. Atomic force microscope with combined FTIR-Raman spectroscopy having a micro thermal analyzer

    Science.gov (United States)

    Fink, Samuel D [Aiken, SC; Fondeur, Fernando F [North Augusta, SC

    2011-10-18

    An atomic force microscope is provided that includes a micro thermal analyzer with a tip. The micro thermal analyzer is configured for obtaining topographical data from a sample. A raman spectrometer is included and is configured for use in obtaining chemical data from the sample.

  12. Nuclear spin dependent atomic parity violation, nuclear anapole moments, and the hadronic axial neutral current

    Energy Technology Data Exchange (ETDEWEB)

    Bouchiat, C.; Piketty, C.A. (Ecole Normale Superieure, 75 - Paris (France). Lab. de Physique Theorique)

    1991-01-01

    Left-right symmetries in atomic transitions, depending upon the nuclear spin, could be a source of information on the neutral hadronic axial current. We show that the relevant electroweak parameter can be extracted from experiment by measuring hyperfine component ratios which do not involve the knowledge of the atomic wave function. In the standard electroweak model, the parity violating electron-nucleus interaction associated with the hadronic axial neutral current is accidently suppressed and, as a consequence, dominated by the electron interaction with the nuclear anapole moment, which describes the effect of the parity violating nuclear forces on the nucleus electromagnetic current. One of our objectives was to identify the various physical mechanisms which determine the size of the nuclear anapole moments. As an important step, we have established a simple relation between the anapole moment and the nuclear spin magnetization. From this relation it follows that the computation of the anapole moment can be reduced to that of one-body operators. The basic tool is a unitary transformation W which eliminates the one-body parity violating potential from the nuclear hamiltonian. A particular attention was paid to nuclear correlation effects. They are treated semi-empirically in the independent pair approximation. The nuclear anapole moments of {sup 85}Rb, {sup 133}Cs, and {sup 209}Bi have been evaluated for three sets of parity violating meson-nucleon coupling constants, taking into account configuration mixing effects in a semi-empirical way. We suggest a possible strategy to disentangle the axial neutral current from the anapole moment contribution. (orig.).

  13. Cooling and trapping of neutral mercury atoms; Kuehlen und Fangen von neutralen Hg-Atomen

    Energy Technology Data Exchange (ETDEWEB)

    Villwock, Patrick

    2010-01-15

    Mercury offers numerous opportunities for experiments in cold atomic and molecular physics. Due to the particular energy level structure of the Hg-dimer it should be possible to efficiently populate the rovibrational ground state by employing a particular absorption-emission scheme after the dimers have been formed via photo association. Cold {sup 199}Hg-atoms in the ground state are very well suited for testing the Bell equations with atoms, because they are ideal spin-1/2-particles. Hg-dimers would be optimal for the search of a permanent electrical dipole moment, due to their mass. An optical lattice clock based on neutral mercury atoms using the {sup 1}S{sub 0}-{sup 3}P{sub 0} clock transition at 265.6 nm with a natural linewidth of about 100 mHz is predicted to reach an accuracy better than 10{sup -18}. The frequency ratio of two optical clocks exhibits the opportunity to test the temporal variation of the fine-structure constant. Laser-cooled neutral Hg-atoms in a magneto-optical trap (MOT) represent a high quality source for a focused ion beam. The isotope selectivity of a MOT offers the potential of producing pure Hg-Isotopes. Mercury has two stable fermionic and five stable bosonic isotopes. The {sup 1}S{sub 0}-{sup 3}P{sub 1} intercombination line at 253.7 nm has a saturation intensity of 10.2 {sup mW}/{sub cm{sup 2}}, with a natural linewidth of 1.27 MHz. This cooling transition is closed since the ground state is free of fine- and hyperfine structure. Consequently no additional repumping is required. Due to the relatively long lifetime of this trapping transition the Doppler limited temperature is 30 μK. This thesis presents the development and experimental setup of a magneto-optical trap for neutral mercury atoms. This undertaking required the development of a commercially unavailable laser source in order to cool and trap Hg-atoms. The cooling transition sets high demands on such a cutting-edge laser, due to its relatively high saturation intensity

  14. Heavy coronal ions in the heliosphere. II. Expected fluxes of energetic neutral He atoms from the heliosheath

    CERN Document Server

    Grzedzielski, S; Bzowski, M

    2012-01-01

    Aims. A model of heliosheath density and energy spectra of alpha-particles and He+ ions carried by the solar wind is developed. Neutralization of heliosheath He+ ions, mainly by charge exchange (CX) with neutral interstellar H and He atoms, gives rise to ~0.2 - ~100 keV fluxes of energetic neutral He atoms (He ENA). Such fluxes, if observed, would give information about plasmas in the heliosheath and heliospheric tail. Methods. Helium ions crossing the termination shock (TS) constitute suprathermal (test) particles convected by (locally also diffusing through) hydrodynamically calculated background plasma flows (three versions of flows are employed). The He ions proceed from the TS towards heliopause (HP) and finally to the heliospheric tail (HT). Calculations of the evolution of alpha- and He+ particle densities and energy spectra include binary interactions with background plasma and interstellar atoms, adiabatic heating (cooling) resulting from flow compression (rarefaction), and Coulomb scattering on back...

  15. Energetic Neutral Atom Emissions From Venus: VEX Observations and Theoretical Modeling

    Science.gov (United States)

    Fok, M.-C.; Galli, A.; Tanaka, T.; Moore, T. E.; Wurz, P.; Holmstrom, M.

    2007-01-01

    Venus has almost no intrinsic magnetic field to shield itself from its surrounding environment. The solar wind thus directly interacts with the planetary ionosphere and atmosphere. One of the by-products of this close encounter is the production of energetic neutral atom (ENA) emissions. Theoretical studies have shown that significant amount of ENAs are emanated from the planet. The launch of the Venus Express (VEX) in 2005 provided the first light ever of the Venus ENA emissions. The observed ENA flux level and structure are in pretty good agreement with the theoretical studies. In this paper, we present VEX ENA data and the comparison with numerical simulations. We seek to understand the solar wind interaction with the planet and the impacts on its atmospheres.

  16. On how the optical depth tunes the effects of ISM neutral atom flow on debris disks

    CERN Document Server

    Marzari, Francesco

    2011-01-01

    The flux of ISM neutral atoms surrounding stars and their environment affects the motion of dust particles in debris disks, causing a significant dynamical evolution. Large values of eccentricity and inclination can be excited and strong correlations settle in among the orbital angles. This dynamical behaviour, in particular for bound dust grains, can potentially cause significant asymmetries in dusty disks around solar type stars which might be detected by observations. However, the amount of orbital changes due to this non--gravitational perturbation is strongly limited by the collisional lifetime of dust particles. We show that for large values of the disk's optical depth the influence of ISM flow on the disk shape is almost negligible because the grains are collisionally destroyed before they can accumulate enough orbital changes due to the ISM perturbations. On the other hand, for values smaller than $10^{-3}$, peculiar asymmetric patterns appear in the density profile of the disk when we consider 1-10 m...

  17. Two Azimuthally Separated Regions of Cusp Ion Injection Observed via Energetic Neutral Atoms

    Science.gov (United States)

    Abe, M.; Taguchi, S.; Collier, M. R.; Moore, T. E.

    2011-01-01

    The low-energy neutral atom (LENA) imager on the IMAGE spacecraft can detect energetic neutral atoms produced by ion injection into the cusp through a charge exchange with the Earth's hydrogen exosphere. We examined the occurrence of the LENA cusp signal during positive IMF B(sub z) in terms of the arrival direction and the IMF clock angle theta(sub CA). Results of statistical analyses show that the occurrence frequency is high on the postnoon side when theta(sub CA) is between approximately 20 degrees and approximately 50 degrees. This is ascribed to ion injection caused by cusp reconnection typical of positive IMF B(sub z). Our results also show that there is another situation of high occurrence frequency, which can be identified with theta(sub CA) of approximately 30 degrees to approximately 80 degrees. When theta(sub CA) is relatively large (60 degrees - 80 degrees), occurrence frequencies are high at relatively low latitudes over a wide extent spanning both prenoon and postnoon sectors. This feature suggests that the ion injection is caused by reconnection at the dayside magnetopause. Its postnoon side boundary shifts toward the prenoon as theta(sub CA) decreases. When theta(sub CA) is less than approximately 50 degrees, the high occurrence frequency exists well inside the prenoon sector, which is azimuthally separated from the postnoon region ascribed to cusp reconnection. The prenoon region, which is thought due to ion injection caused by dayside reconnection, may explain the recent report that proton aurora brightening occurs in the unanticipated prenoon sector of the northern high-latitude ionosphere for IMF B(sub y) greater than 0 and B(sub z) greater than 0.

  18. Energetic Neutral Atom (ENA) Movies and Other Cool Data from Cassini's Magnetosphere Imaging Instrument (MIMI)

    Science.gov (United States)

    Kusterer, M. B.; Mitchell, D. G.; Krimigis, S. M.; Vandegriff, J. D.

    2014-12-01

    Having been at Saturn for over a decade, the MIMI instrument on Cassini has created a rich dataset containing many details about Saturn's magnetosphere. In particular, the images of energetic neutral atoms (ENAs) taken by the Ion and Neutral Camera (INCA) offer a global perspective on Saturn's plasma environment. The MIMI team is now regularly making movies (in MP4 format) consisting of consecutive ENA images. The movies correct for spacecraft attitude changes by projecting the images (whose viewing angles can substantially vary from one image to the next) into a fixed inertial frame that makes it easy to view spatial features evolving in time. These movies are now being delivered to the PDS and are also available at the MIMI team web site. Several other higher order products are now also available, including 20-day energy-time spectrograms for the Charge-Energy-Mass Spectrometer (CHEMS) sensor, and daily energy-time spectrograms for the Low Energy Magnetospheric Measurements system (LEMMS) sensor. All spectrograms are available as plots or digital data in ASCII format. For all MIMI sensors, a Data User Guide is also available. This paper presents details and examples covering the specifics of MIMI higher order data products. URL: http://cassini-mimi.jhuapl.edu/

  19. Scattering characteristics and imaging of energetic neutral atoms from the Moon in the terrestrial magnetosheath

    Science.gov (United States)

    Lue, Charles; Futaana, Yoshifumi; Barabash, Stas; Saito, Yoshifumi; Nishino, Masaki; Wieser, Martin; Asamura, Kazushi; Bhardwaj, Anil; Wurz, Peter

    2016-01-01

    We study hydrogen energetic neutral atom (ENA) emissions from the lunar surface, when the Moon is inside the terrestrial magnetosheath. The ENAs are generated by neutralization and backscattering of incident protons of solar wind origin. First, we model the effect of the increased ion temperature in the magnetosheath (>10 times larger than that in the undisturbed solar wind) on the ENA scattering characteristics. Then, we apply these models to ENA measurements by Chandrayaan-1 and simultaneous ion measurements by Kaguya at the Moon, in the magnetosheath. We produce maps of the ENA scattering fraction, covering a region at the lunar near-side that includes mare and highland surfaces and several lunar magnetic anomalies. We see clear signatures of plasma shielding by the magnetic anomalies. The maps are made at different lunar local times, and the results indicate an extended influence and altered morphology of the magnetic anomalies at shallower incidence angles of the magnetosheath protons. The scattering fraction from the unmagnetized regions remains consistent with that in the undisturbed solar wind (10%-20%). Moreover, the observed ENA energy spectra are well reproduced by our temperature-dependent model. We conclude that the ENA scattering process is unchanged in the magnetosheath. Similarly to the undisturbed solar wind case, it is only magnetic anomalies that provide contrast in the ENA maps, not any selenomorphological features such as mare and highland regions.

  20. Energetic neutral atoms measured by the interstellar boundary explorer (IBEX): Evidence for multiple heliosheath populations

    Energy Technology Data Exchange (ETDEWEB)

    Desai, M. I.; Allegrini, F. A.; Dayeh, M. A.; Fuselier, S. A.; McComas, D. J. [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States); Bzowski, M.; Kubiak, M. A.; Sokół, J. M. [Space Research Centre, PAS, Warsaw (Poland); Funsten, H. [Los Alamos National Laboratory, Los Alamos, New Mexico, NM 87545 (United States); Heerikhuisen, J.; Pogorelov, N. V.; Zank, G. P.; Zirnstein, E. J. [The Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL 35805 (United States); Schwadron, N. A., E-mail: mdesai@swri.edu [Department of Physics and Space Science Center, University of New Hampshire, Durham, NH 03824 (United States)

    2014-01-01

    Energetic neutral atoms (ENAs) observed by the Interstellar Boundary Explorer (IBEX) provide powerful diagnostics about the origin of the progenitor ion populations and the physical mechanisms responsible for their production. In this paper, we extend the work of Desai et al. and Fuselier et al. and combine and compare ENA spectra from the first 3 yr of observations by the IBEX-Hi and -Lo ENA imagers along the lines-of-sight (LOSs) from the inner heliosphere through to the locations of Voyager 1 and 2 with results from an updated physics-based model of the three-dimensional heliosphere and its constituent ion populations. Our results show that (1) IBEX ENA fluxes and spectra above ∼0.7 keV measured along the LOSs of the Voyagers are consistent with several models in which the parent pickup ion (PUI) populations originate in the inner heliosheath, and (2) a significant fraction of lower energy ENAs between ∼0.1-0.5 keV may originate from interstellar neutral gas charge-exchanging with a non-thermalized (hot) population of PUIs in the outer heliosheath beyond the heliopause. We discuss the implications of ENAs observed by IBEX originating from distinct parent populations as well as from two distinct locations in the heliospheric interface. These results indicate that ENA spectral measurements at various energies can be used to remotely probe distinct physical processes operating in vastly different regions of the distant heliosphere.

  1. VUV absorption spectroscopy measurements of the role of fast neutral atoms in high-power gap breakdown

    Energy Technology Data Exchange (ETDEWEB)

    FILUK,A.B.; BAILEY,JAMES E.; CUNEO,MICHAEL E.; LAKE,PATRICK WAYNE; NASH,THOMAS J.; NOACK,DONALD D.; MARON,Y.

    2000-03-20

    The maximum power achieved in a wide variety of high-power devices, including electron and ion diodes, z pinches, and microwave generators, is presently limited by anode-cathode gap breakdown. A frequently-discussed hypothesis for this effect is ionization of fast neutral atoms injected throughout the anode-cathode gap during the power pulse. The authors describe a newly-developed diagnostic tool that provides the first direct test of this hypothesis. Time-resolved vacuum-ultraviolet absorption spectroscopy is used to directly probe fast neutral atoms with 1 mm spatial resolution in the 10 mm anode-cathode gap of the SABRE 5 MV, 1 TW applied-B ion diode. Absorption spectra collected during Ar RF glow discharges and with CO{sub 2} gas fills confirm the reliability of the diagnostic technique. Throughout the 50--100 ns ion diode pulses no measurable neutral absorption is seen, setting upper limits of 0.12--1.5 x 10{sup 14} cm{sup {minus}3} for ground state fast neutral atom densities of H, C, N, O, F. The absence of molecular absorption bands also sets upper limits of 0.16--1.2 x 10{sup 15} cm{sup {minus}3} for common simple molecules. These limits are low enough to rule out ionization throughout the gap as a breakdown mechanism. This technique can now be applied to quantify the role of neutral atoms in other high-power devices.

  2. LabKey Server NAb: A tool for analyzing, visualizing and sharing results from neutralizing antibody assays

    Directory of Open Access Journals (Sweden)

    Gao Hongmei

    2011-05-01

    Full Text Available Abstract Background Multiple types of assays allow sensitive detection of virus-specific neutralizing antibodies. For example, the extent of antibody neutralization of HIV-1, SIV and SHIV can be measured in the TZM-bl cell line through the degree of luciferase reporter gene expression after infection. In the past, neutralization curves and titers for this standard assay have been calculated using an Excel macro. Updating all instances of such a macro with new techniques can be unwieldy and introduce non-uniformity across multi-lab teams. Using Excel also poses challenges in centrally storing, sharing and associating raw data files and results. Results We present LabKey Server's NAb tool for organizing, analyzing and securely sharing data, files and results for neutralizing antibody (NAb assays, including the luciferase-based TZM-bl NAb assay. The customizable tool supports high-throughput experiments and includes a graphical plate template designer, allowing researchers to quickly adapt calculations to new plate layouts. The tool calculates the percent neutralization for each serum dilution based on luminescence measurements, fits a range of neutralization curves to titration results and uses these curves to estimate the neutralizing antibody titers for benchmark dilutions. Results, curve visualizations and raw data files are stored in a database and shared through a secure, web-based interface. NAb results can be integrated with other data sources based on sample identifiers. It is simple to make results public after publication by updating folder security settings. Conclusions Standardized tools for analyzing, archiving and sharing assay results can improve the reproducibility, comparability and reliability of results obtained across many labs. LabKey Server and its NAb tool are freely available as open source software at http://www.labkey.com under the Apache 2.0 license. Many members of the HIV research community can also access the Lab

  3. LabKey Server NAb: A tool for analyzing, visualizing and sharing results from neutralizing antibody assays

    Science.gov (United States)

    2011-01-01

    Background Multiple types of assays allow sensitive detection of virus-specific neutralizing antibodies. For example, the extent of antibody neutralization of HIV-1, SIV and SHIV can be measured in the TZM-bl cell line through the degree of luciferase reporter gene expression after infection. In the past, neutralization curves and titers for this standard assay have been calculated using an Excel macro. Updating all instances of such a macro with new techniques can be unwieldy and introduce non-uniformity across multi-lab teams. Using Excel also poses challenges in centrally storing, sharing and associating raw data files and results. Results We present LabKey Server's NAb tool for organizing, analyzing and securely sharing data, files and results for neutralizing antibody (NAb) assays, including the luciferase-based TZM-bl NAb assay. The customizable tool supports high-throughput experiments and includes a graphical plate template designer, allowing researchers to quickly adapt calculations to new plate layouts. The tool calculates the percent neutralization for each serum dilution based on luminescence measurements, fits a range of neutralization curves to titration results and uses these curves to estimate the neutralizing antibody titers for benchmark dilutions. Results, curve visualizations and raw data files are stored in a database and shared through a secure, web-based interface. NAb results can be integrated with other data sources based on sample identifiers. It is simple to make results public after publication by updating folder security settings. Conclusions Standardized tools for analyzing, archiving and sharing assay results can improve the reproducibility, comparability and reliability of results obtained across many labs. LabKey Server and its NAb tool are freely available as open source software at http://www.labkey.com under the Apache 2.0 license. Many members of the HIV research community can also access the LabKey Server NAb tool without

  4. Observation and Interpretation of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Flare

    Science.gov (United States)

    Barghouty, A. F.; Mewaldt, R. A.; Leske, R. A.; Shih, A. Y.; Stone, E. C.; Cohen, C. M. S.; Cummings, A. C.; Labrador, A. W.; vonRosenvinge, T. T.; Wiedenbeck, M. E.

    2009-01-01

    We discuss observations of energetic neutral hydrogen atoms (ENAs) from a solar flare/coronal mass ejection event reported by Mewaldt et al. (2009). The observations were made during the 5 December 2006 X9 solar flare, located at E79, by the Low Energy Telescopes (LETs) on STEREO A and B. Prior to the arrival of the main solar energetic particle (SEP) event at Earth, both LETs observed a sudden burst of 1.6 to 15 MeV particles arriving from the Sun. The derived solar emission profile, arrival directions, and energy spectrum all show that the atoms produced by either flare or shock-accelerated protons. RHESSI measurements of the 2.2-MeV gamma-ray line provide an estimate of the number of interacting flare-accelerated protons in this event, which leads to an improved estimate of ENA production by flare-accelerated protons. CME-driven shock acceleration is also considered. Taking into account ENA losses, we conclude that the observed ENAs must have been produced in the high corona at heliocentric distances .2 solar radii.

  5. Energetic neutral helium atoms as a tool to study the heliosphere and the local interstellar medium

    Science.gov (United States)

    Swaczyna, Pawel; Grzedzielski, Stan; Bzowski, Maciej

    2015-04-01

    The aim of our study is to determine the utility of helium energetic neutral atoms (ENA) in the studies of the outer heliosphere, its boundary region, and the nearby interstellar medium, and to assess the requirements for future instruments to enable them to observe He ENA fluxes. Presently, studying these regions is rendered possible mostly by combining the in-situ measurements by the plasma and cosmic-ray instruments on Voyagers and the remote-sensing observations of H ENA from IBEX. Helium as the second most abundant species in the universe could potentially enable further extension of our knowledge about nearest surroundings of the Sun. We assessed the expected emission of the heliospheric He ENA and of He ENA from the nearby interstellar medium. To estimate the heliospheric emission of He ENA we used a simple model of the heliosphere and performed numerical simulations to determine the distribution of various populations of helium ions in the inner heliosphere. Based on this model, we calculated fluxes of He ENA created by charge exchange between helium ions and neutral atoms over a wide energy range from 0.5 keV/nuc up to 1 MeV/nuc. We included binary interactions between various combinations of hydrogen and helium ions and atoms. We also included the signal from the vicinity of the heliosphere produced via the secondary ENA mechanism, which is most likely the source for the observed IBEX Ribbon. The mean free path against ionization of He ENA in the local interstellar medium reaches about 8000 AU for atoms with an energy of a few keV. This is about 10 times more than the mean free path against ionization for hydrogen atoms at the same energy. Thus emission of helium ENA from hypothetic extraheliospheric sources could be detectable from larger distances than the hydrogen atoms. This could provide a novel method of sounding the sources of suprathermal ions that might operate in the surrounding of the heliosphere. The He ENA produced by charge-exchange could

  6. Sensing the Heliosheath from Inner Heliosphere via Energetic Neutral Atoms (ENA): a Review

    Science.gov (United States)

    Hsieh, K.

    2008-12-01

    Recently, L. Wang, R. P. Lin, D. E. Larson and J. G. Luhmann reported the detection of 4-20 keV energetic neutral atoms (ENA), most likely H atoms, coming from the frontal lobe of the heliosphere (Nature, Vol. 454, p. 81-83, 3 July 2008). The detection was performed by the suprathermal electron (STE) sensor on the STEREO A and B spacecraft from June to October 2007. The report showed the ENA flux peaking at about 5 and 20 degrees in ecliptic longitude, respectively, on either side of the Apex, the direction of Sun's motion relative to the local interstellar medium. Each peak has a full-width at half-maximum of about 20 degrees, with the one at the lower ecliptic longitude having a peak flux about three times that of the peak at the higher ecliptic longitude. The same report also derived the spectral shape of the shock-accelerated pick-up ions in the heliosheath to be two power-law spectra with a knee at about 11 keV. Assuming a healiosheath thickness of 40 AU at Voyager 2's crossing of the termination shock, the extrapolation of this proton spectrum into higher energy meets the extrapolation of the ion spectrum measured by Voyager 1 at about 25 keV. These results, especially the double peaking in the ENA flux, appear puzzling to some theorists and modelers of the heliosphere. This talk shall review the analysis of the STE/STEREO data, and go on to discuss the interpretation of the data and its consequences concerning the thickness and shape of the heliosheath as well as the variation of the availability of shock-accelerated ions in the frontal portion of the termination shock. We also compare this most recent ENA observation and implication on the heliosheath with the earlier observation of heliospheric neutral H atoms by SOHO in the energy interval 55-88 keV and the information on the heliosheath deduced from it. If we accept the analysis by Wang et al., then the STE/STEREO observation not only confirms that ion populations in the remotest regions of our

  7. A Rydberg blockade CNOT gate and entanglement in a 2D array of neutral atom qubits

    CERN Document Server

    Maller, K M; Xia, T; Sun, Y; Piotrowicz, M J; Carr, A W; Isenhower, L; Saffman, M

    2015-01-01

    We present experimental results on two-qubit Rydberg blockade quantum gates and entanglement in a two-dimensional qubit array. Without post selection against atom loss we achieve a Bell state fidelity of $0.73\\pm 0.05$, the highest value reported to date. The experiments are performed in an array of single Cs atom qubits with a site to site spacing of $3.8 ~ \\mu\\rm m$. Using the standard protocol for a Rydberg blockade C$_Z$ gate together with single qubit operations we create Bell states and measure their fidelity using parity oscillations. We analyze the role of AC Stark shifts that occur when using two-photon Rydberg excitation and show how to tune experimental conditions for optimal gate fidelity.

  8. Investigating Global Ion and Neutral Atom Populations with IBEX and Voyager

    Science.gov (United States)

    Florinski, Vladimir

    2016-01-01

    The main objective of this project was to investigate pickup ion (PUI) production in the solar wind and heliosheath (the region between the termination shock and the heliopause) and compute the distributed energetic neutral atom fluxes throughout the helioshpere. The simulations were constrained by comparing the model output against observations from Ulysses, New Horizons, Voyager 1 and 2, and IBEX space probes. As evidenced by the number of peer reviewed journal publications resulting from the project (13 plus three submitted) and their citation rate (156 citations over three years), the project has made a lasting contribution to the field. The outcome is a significant improvement of our understanding of the pickup ion production and distribution in the distant heliosphere. The team has accomplished the entire set of tasks A-H set forth in the proposal. Namely, the transport modeling framework has been augmented with two populations of pickup ions (PUIs), the boundary conditions for the plasma and interstellar neutral hydrogen were verified against Ulysses and New Horizons PUI and an optimal set of velocity diffusion parameters established. The multi-component fluxes of PUIs were computed and isotropic velocity distributions generated for each cell in the computer simulation that covered the heliosphere from 1.5 AU to the heliopause. The distributions were carefully compared with in situ measurements at 3 AU (Ulysses), 12 AU (New Horizons), and 80-90 AU (Voyager 1 and 2) as well as those inferred from ENA fluxes measured by Cassini and IBEX (Wu et al., 2016). Some examples of modeldata comparison are shown in Figure 1. We have used coupled MHD-plasma and kinetic-neutral code to investigate the likely range of plasma and magnetic field parameters in the local interstellar medium (LISM), based on the assumption that the shape of the IBEX ribbon could be used to determine the orientation of the interstellar magnetic field. While the magnetic field is believed to be

  9. Observation and Interpretation of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Event

    Science.gov (United States)

    Mewaldt, R. A.; Leske, R. A.; Stone, E. C.; Barghouty, A. F.; Shih, A. Y.; von Rosenvinge, T. T.; Labrador, A. W.; Cohen, C. M. S.; Cummings, A. C.; Cummings, A. C.

    2009-01-01

    We report the first observations of energetic neutral atoms (ENAs) from a solar flare/coronal mass ejection event. The observations were made during the December 5, 2006 X9 solar flare, located at E79, by the Low Energy Telescopes (LETs) on the STEREO A and B spacecraft. Within 1-2 hours of the flare onset, both LETs observed a sudden burst of 1.6 to 15 MeV protons arriving hours before the onset of the main solar energetic particle (SEP) event at Earth. More than 70% of these particles arrived from a longitude within +-10 degrees of the Sun. The derived emission profile at the Sun lasted for more than an hour and had a profile remarkably similar to the GOES soft X-ray profile. The observed arrival directions and energy spectrum argue strongly that the particle events atoms that were stripped of their electrons upon entering the LET sensor. To our knowledge, this is the first reported observation of ENA emission from a solar flare/coronal mass ejection. We discuss possible origins for the production of ENAs in solar events, including charge-transfer reactions involving both flare and shock-accelerated protons. Assuming isotropic emission, we find that 2 x 10E28 ENAs escaped from the Sun in the upper hemisphere. Based on the 2.2 MeV gamma-ray emission observed by RHESSI in this event, and using measured and theoretical cross sections, we estimate that 3 x 10E31 ENAs with 1.8 - 5 MeV could be produced by protons accelerated in the flare. CME-driven shock acceleration is also a possible ENA source, but unfortunately there were no CME observations available from this event. Taking into account ENA losses, we conclude that the observed ENAs were most likely produced in the high corona at heliocentric distances 1.6 solar radii.

  10. Compact and multi-view solid state neutral particle analyzer arrays on National Spherical Torus Experiment-Upgrade

    Science.gov (United States)

    Liu, D.; Heidbrink, W. W.; Tritz, K.; Fredrickson, E. D.; Hao, G. Z.; Zhu, Y. B.

    2016-11-01

    A compact and multi-view solid state neutral particle analyzer (SSNPA) diagnostic based on silicon photodiode arrays has been successfully tested on the National Spherical Torus Experiment-Upgrade. The SSNPA diagnostic provides spatially, temporally, and pitch-angle resolved measurements of fast-ion distribution by detecting fast neutral flux resulting from the charge exchange (CX) reactions. The system consists of three 16-channel subsystems: t-SSNPA viewing the plasma mid-radius and neutral beam (NB) line #2 tangentially, r-SSNPA viewing the plasma core and NB line #1 radially, and p-SSNPA with no intersection with any NB lines. Due to the setup geometry, the active CX signals of t-SSNPA and r-SSNPA are mainly sensitive to passing and trapped particles, respectively. In addition, both t-SSNPA and r-SSNPA utilize three vertically stacked arrays with different filter thicknesses to obtain coarse energy information. The experimental data show that all channels are operational. The signal to noise ratio is typically larger than 10, and the main noise is x-ray induced signal. The active and passive CX signals are clearly observed on t-SSNPA and r-SSNPA during NB modulation. The SSNPA data also indicate significant losses of passing particles during sawteeth, while trapped particles are weakly affected. Fluctuations up to 120 kHz have been observed on SSNPA, and they are strongly correlated with magnetohydrodynamics instabilities.

  11. The Interstellar Boundary Explorer (IBEX): Tracing the Interaction between the Heliosphere and Surrounding Interstellar Material with Energetic Neutral Atoms

    CERN Document Server

    Frisch, Priscilla C

    2010-01-01

    The Interstellar Boundary Explorer (IBEX) mission is exploring the frontiers of the heliosphere where energetic neutral atoms (ENAs) are formed from charge exchange between interstellar neutral hydrogen atoms and solar wind ions and pickup ions. The geography of this frontier is dominated by an unexpected nearly complete arc of ENA emission, now known as the IBEX 'Ribbon'. While there is no consensus agreement on the Ribbon formation mechanism, it seems certain this feature is seen for sightlines that are perpendicular to the interstellar magnetic field as it drapes over the heliosphere. At the lowest energies, IBEX also measures the flow of interstellar H, He, and O atoms through the inner heliosphere. The asymmetric helium profile suggests that a secondary flow of helium is present, such as would be expected if some fraction of helium is lost through charge exchange in the heliosheath regions. The detailed spectra characterized by the ENAs provide time-tagged samples of the energy distributions of the under...

  12. Analytical expression for K- and L-shell cross sections of neutral atoms near ionization threshold by electron impact

    Energy Technology Data Exchange (ETDEWEB)

    Campos, C S [Instituto de Geociencias, Centro de Pesquisa em Geologia e GeofIsica, Universidade Federal da Bahia (UFBA), 40170-290 Salvador (Brazil); Vasconcellos, M A Z [Instituto de Fisica, Universidade Federal do Rio Grande do Sul (UFRGS), 91501-970 Porto Alegre, RS (Brazil); Trincavelli, J C [Facultad de Matematica, AstronomIa y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina); Segui, S [Centro Atomico Bariloche, Comision Nacional de EnergIa Atomica, 8400 San Carlos de Bariloche, RIo Negro (Argentina)

    2007-10-14

    An analytical expression is proposed to describe the K- and L-shell ionization cross sections of neutral atoms by electron impact over a wide range of atomic numbers (4 {<=} Z {<=} 79) and over voltages U < 10. This study is based on the analysis of a calculated ionization cross section database using the distorted-wave first-order Born approximation (DWBA). The expression proposed for cross sections relative to their maximum height involves only two parameters for each atomic shell, with no dependence on the atomic number. On the other hand, it is verified that these parameters exhibit a monotonic behaviour with the atomic number for the absolute ionization cross sections, which allows us to obtain analytical expressions for the latter.

  13. Energetic Neutral Atom Imaging with the POLAR CEPPAD/ IPS Instrument : Initial Forward Modeling Results

    Science.gov (United States)

    Henderson, M. G.; Reeves, G. D.; Moore, K. R.; Spence, H. E.; Jorgensen, A. M.; Fennell, J. F.; Blake, J. B.; Roelof, E. C.

    1999-01-01

    Although the primary function of the CEPPAD/IPS instrument on Polar is the measurement of energetic ions in-situ, it has also proven to be a very capable Energetic Neutral Atom (ENA) imager. Raw ENA images are currently being constructed on a routine basis with a temporal resolution of minutes during both active and quiet times. However, while analyses of these images by themselves provide much information on the spatial distribution and dynamics of the energetic ion population in the ring current. detailed modeling is required to extract the actual ion distributions. In this paper. we present the initial results of forward modeling an IPS ENA image obtained during a small geo-magnetic storm on June 9, 1997. The equatorial ion distribution inferred with this technique reproduces the expected large noon/midnight and dawn/dusk asymmetries. The limitations of the model are discussed and a number of modifications to the basic forward modeling technique are proposed which should significantly improve its performance in future studies.

  14. Latitude, Energy, and Time Variations of Energetic Neutral Atom Spectral indices Measured by IBEX

    Science.gov (United States)

    Desai, Mihir; Heerikhuisen, Jacob; McComas, David; Funsten, Herbert; Pogorelov, Nikolai; Zank, Gary; Schwadron, Nathan; Fuselier, Stephen; Allegrini, Frederic; Dayeh, Maher A.

    2016-07-01

    We investigate the latitude, energy, and time variations of the globally distributed 0.5-6 keV energetic neutral atom (ENA) spectra measured by the Interstellar Boundary Explorer (IBEX) during the first 5 years of the mission. Our previous results based on the first 3 years of IBEX observations showed that the ENA spectral indices at the two lowest energies (0.89 and 1.47 keV) exhibit no clear trend with ecliptic latitude θ, while those at ˜2.29 and ˜3.41 keV exhibit a clear latitudinal pattern; flatter spectra occur above 60° latitude and steeper spectra occur within ±30° of the equator. While these results confirmed the previously reported latitudinal organization of the ENA spectra and their remarkable similarity to that of the solar wind (SW) speed observed by Ulysses in the inner heliosphere, we also showed that, unlike previous reports, the ˜0.5-6 keV globally distributed ENA spectral indices could not be represented as single power laws over much of the sky, and that they depend on energy and latitude. In this paper we extend the above results to include years 4 and 5 of IBEX observations and investigate if the spectral indices vary as a function of time. Finally, we discuss implications of our results on models and simulations that seek to map the IBEX ENA observations back to the latitudinal profile of the SW speed structure observed in the inner heliosphere.

  15. SYMMETRY OF THE IBEX RIBBON OF ENHANCED ENERGETIC NEUTRAL ATOM (ENA) FLUX

    Energy Technology Data Exchange (ETDEWEB)

    Funsten, H. O.; Cai, D. M.; Higdon, D. M.; Larsen, B. A., E-mail: hfunsten@lanl.gov, E-mail: dmc@lanl.gov, E-mail: dhigdon@lanl.gov, E-mail: balarsen@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); and others

    2015-01-20

    The circular ribbon of enhanced energetic neutral atom (ENA) emission observed by the Interstellar Boundary Explorer (IBEX) mission remains a critical signature for understanding the interaction between the heliosphere and the interstellar medium. We study the symmetry of the ribbon flux and find strong, spectrally dependent reflection symmetry throughout the energy range 0.7-4.3 keV. The distribution of ENA flux around the ribbon is predominantly unimodal at 0.7 and 1.1 keV, distinctly bimodal at 2.7 and 4.3 keV, and a mixture of both at 1.7 keV. The bimodal flux distribution consists of partially opposing bilateral flux lobes, located at highest and lowest heliographic latitude extents of the ribbon. The vector between the ribbon center and heliospheric nose (which defines the so-called BV plane) appears to play an organizing role in the spectral dependence of the symmetry axis locations as well as asymmetric contributions to the ribbon flux. The symmetry planes at 2.7 and 4.3 keV, derived by projecting the symmetry axes to a great circle in the sky, are equivalent to tilting the heliographic equatorial plane to the ribbon center, suggesting a global heliospheric ordering. The presence and energy dependence of symmetric unilateral and bilateral flux distributions suggest strong spectral filtration from processes encountered by an ion along its journey from the source plasma to its eventual detection at IBEX.

  16. Are the sungrazing comets the inner source of pickup ions and energetic neutral atoms?

    CERN Document Server

    Bzowski, M

    2004-01-01

    We show arguments that at least part of the inner source of pickup ions and energetic neutral atoms (~ 1 keV) might be the material released by sungrazing comets.Based on the monthly apparition statistics we postulate that the actual number of sungrazing comets may be even higher than observed. We point out that an overwhelming majority of the observed sungrazers belong to the Kreutz group of comets which follow tightly clumped orbits and break up at $\\sim 40 - 4$ solar radii in a well defined region. The material released from these comets should be (after ionization) at least an important portion of the inner source of pickup ions. We suggest that PUI from the cometary source should be accompanied by an increased level of ENA of similar energy. We indicate time intervals during the year when the cometary PUI should be observed from a spacecraft at Earth's orbit (basically, from the end of July till the end of the year) and show three time intervals, when they should be observable by Ulysses (since launch ti...

  17. Separation of the Interstellar Boundary Explorer Ribbon from Globally Distributed Energetic Neutral Atom Flux

    Science.gov (United States)

    Schwadron, N. A.; Allegrini, F.; Bzowski, M.; Christian, E. R.; Crew, G. B.; Dayeh, M.; DeMajistre, R.; Frisch, P.; Funsten, H. O.; Fuselier, S. A.; Goodrich, K.; Gruntman, M.; Janzen, P.; Kucharek, H.; Livadiotis, G.; McComas, D. J.; Moebius, E.; Prested, C.; Reisenfeld, D.; Reno, M.; Roelof, E.; Siegel, J.; Vanderspek, R.

    2011-04-01

    The Interstellar Boundary Explorer (IBEX) observes a remarkable feature, the IBEX ribbon, which has energetic neutral atom (ENA) flux over a narrow region ~20° wide, a factor of 2-3 higher than the more globally distributed ENA flux. Here, we separate ENA emissions in the ribbon from the distributed flux by applying a transparency mask over the ribbon and regions of high emissions, and then solve for the distributed flux using an interpolation scheme. Our analysis shows that the energy spectrum and spatial distribution of the ribbon are distinct from the surrounding globally distributed flux. The ribbon energy spectrum shows a knee between ~1 and 4 keV, and the angular distribution is approximately independent of energy. In contrast, the distributed flux does not show a clear knee and more closely conforms to a power law over much of the sky. Consistent with previous analyses, the slope of the power law steepens from the nose to tail, suggesting a weaker termination shock toward the tail as compared to the nose. The knee in the energy spectrum of the ribbon suggests that its source plasma population is generated via a distinct physical process. Both the slope in the energy distribution of the distributed flux and the knee in the energy distribution of the ribbon are ordered by latitude. The heliotail may be identified in maps of globally distributed flux as a broad region of low flux centered ~44°W of the interstellar downwind direction, suggesting heliotail deflection by the interstellar magnetic field.

  18. A theoretical analysis of parity violation induced by neutral currents in atomic cesium

    Science.gov (United States)

    Bouchiat, C.; Piketty, C. A.; Pignon, D.

    1983-07-01

    In this paper we give a theoretical analysis of the parity violation phenomena in nS - n'S transitions in atomic cesium induced by the electron-nucleus neutral-current interaction. The actual observation of parity violation consists in the measurement of an interference between the p.v. electric dipole amplitude Elpv with the electric amplitude induced by a static electric field. Our theoretical work must then include a calculation of the diagonal and non-diagonal polarizabilities of the states of atomic cesium. We have used a one-electron model proposed by Norcross which incorporates some many-body effects like the electric screening induced by the core polarization in a semi-empirical way. Our calculated values of the diagonal and non-diagonal polarizabilities of the nS states are in good agreement with the existing measurements; this confirms the already well-established success of the model in predicting the radiative transitions in cesium. We present theoretical arguments supported by detailed numerical computations showing that the one-particle matrix element of the parity-violating electron-nucleus interaction and the parity-violating electric dipole amplitude Elpv itself weakly depend on the shape of the one-electron potential provided the binding energies of the valence states are reproduced accurately. Furthermore it turns out that because of a compensation mechanism, the parity-violating transition is induced by the radiation field outside the ion core region where the screening can be described simply in terms of the measurable cesium ion polarizability. Our results are then used to extract, from the Ecole Normale Supérieure experiment, a value of the weak charge Qw = -57.1 ± 9.4 (r.m.s. statistical deviation) ± 4.7 (systematic uncertainty). This number is to be compared with the prediction of the Weinberg-Salam model with electro-weak radiative corrections: Qw = -68.6 ± 3.0. A general discussion of the uncertainties of the atomic physics

  19. State-resolved study of keV sputtered neutral atoms by resonance ionization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    He, C.; Postawa, Z.; Rosencrance, S.; Chatterjee, R.; Garrison, B.J.; Winograd, N. [Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    1995-04-01

    We have performed simultaneous measurements of energy-, and angle-resolved distributions of Ni atoms desorbed from a single crystal Ni{l_brace}100{r_brace} surface bombarded by 5 keV Ar{sup +} ions. Ground state and six low-lying excited states from the {ital a}{sup 3}{ital F}{sub {ital J}} ({ital J}=4,3,2) and {ital a}{sup 3}{ital D}{sub {ital J}} ({ital J}=3,2,1) manifolds as well as {ital a}{sup 1}{ital D}{sub 2} have been investigated along different azimuths. Both {ital a}{sup 3}{ital F}{sub {ital J}} and {ital a}{sup 1}{ital D}{sub 2} states have closed shell electronic structure, 3{ital d}{sup 8}4{ital s}{sup 2}, while the {ital a}{sup 3}{ital D}{sub {ital J}} states are open shell electronic states, 3{ital d}{sup 9}4{ital s}{sup 1}. Angle-integrated energy distributions demonstrate a strong dependence on the electronic structure while the magnitude of the excitation energy does not significantly alter the results. This is the first conclusive evidence that electronic structure rather than excitation energy is the primary factor in determining kinetic energy distributions of sputtered neutral species. Population distribution among the seven electronic states are obtained through two sets of measurements performed on two experimental apparati: one measures the energy- and angle-integrated resonance ionization signal intensities of the sputtered Ni; the other measures the resonance ionization signal intensities of thermally evaporated Ni atoms with a known heating temperature. The experiment results show that the population distribution is very different from Boltzman-type distribution with {ital a}{sup 3}{ital D}{sub 3} and {ital a}{sup 3}{ital D}{sub 2} states more intensely populated. The work also illustrates the power of RIS to perform quantum state specific measurements on fast moving atoms. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}

  20. Use of Atomic Fuels for Rocket-Powered Launch Vehicles Analyzed

    Science.gov (United States)

    Palaszewski, Bryan A.

    1999-01-01

    At the NASA Lewis Research Center, the launch vehicle gross lift-off weight (GLOW) was analyzed for solid particle feed systems that use high-energy density atomic propellants (ref. 1). The analyses covered several propellant combinations, including atoms of aluminum, boron, carbon, and hydrogen stored in a solid cryogenic particle, with a cryogenic liquid as the carrier fluid. Several different weight percents for the liquid carrier were investigated, and the GLOW values of vehicles using the solid particle feed systems were compared with that of a conventional oxygen/hydrogen (O2/H2) propellant vehicle. Atomic propellants, such as boron, carbon, and hydrogen, have an enormous potential for high specific impulse Isp operation, and their pursuit has been a topic of great interest for decades. Recent and continuing advances in the understanding of matter, the development of new technologies for simulating matter at its most basic level, and manipulations of matter through microtechnology and nanotechnology will no doubt create a bright future for atomic propellants and an exciting one for the researchers exploring this technology.

  1. Core-ion temperature measurement of the ADITYA tokamak using passive charge exchange neutral particle energy analyzer.

    Science.gov (United States)

    Pandya, Santosh P; Ajay, Kumar; Mishra, Priyanka; Dhingra, Rajani D; Govindarajan, J

    2013-02-01

    Core-ion temperature measurements have been carried out by the energy analysis of passive charge exchange (CX) neutrals escaping out of the ADITYA tokamak plasma (minor radius, a = 25 cm and major radius, R = 75 cm) using a 45° parallel plate electrostatic energy analyzer. The neutral particle analyzer (NPA) uses a gas cell configuration for re-ionizing the CX-neutrals and channel electron multipliers (CEMs) as detectors. Energy calibration of the NPA has been carried out using ion-source and ΔE∕E of high-energy channel has been found to be ∼10%. Low signal to noise ratio (SNR) due to VUV reflections on the CEMs was identified during the operation of the NPA with ADITYA plasma discharges. This problem was rectified by upgrading the system by incorporating the additional components and arrangements to suppress VUV radiations and improve its VUV rejection capabilities. The noise rejection capability of the NPA was experimentally confirmed using a standard UV-source and also during the plasma discharges to get an adequate SNR (>30) at the energy channels. Core-ion temperature Ti(0) during flattop of the plasma current has been measured to be up to 150 eV during ohmically heated plasma discharges which is nearly 40% of the average core-electron temperature (typically Te(0) ∼ 400 eV). The present paper describes the principle of tokamak ion temperature measurement, NPA's design, development, and calibration along with the modifications carried out for minimizing the interference of plasma radiations in the CX-spectrum. Performance of the NPA during plasma discharges and experimental results on the measurement of ion-temperature have also been reported here.

  2. Theoretical analysis of parity violation induced by neutral currents in atomic cesium

    Energy Technology Data Exchange (ETDEWEB)

    Bouchiat, C.; Piketty, C.A.; Pignon, D. (Ecole Normale Superieure, 75 - Paris (France). Lab. de Physique Theorique)

    1983-07-04

    In this paper we give a theoretical analysis of the parity violation phenomena in nS-n'S transitions in atomic cesium induced by the electron-nucleus neutral-current interaction. The actual observation of parity violation consists in the measurement of an interference between the p.v. electric dipole amplitude E/sub 1/sup(pv) with the electric amplitude induced by a static electric field. Our theoretical work must then include a calculation of the diagonal and non-diagonal polarizabilities of the states of atomic cesium. We have used a one-electron model proposed by Norcross which incorporates some many-body effects like the electric screening induced by the core polarization in a semi-empirical way. Our calculated values of the diagonal and non-diagonal polarizabilities of the nS states are in good agreement with the existing measurements; this confirms the already well-established success of the model in predicting the radiative transitions in cesium. We present theoretical arguments supported by detailed numerical computations showing that the one-particle matrix element of the parity-violating electron-nucleus interaction and the parity-violating electric dipole amplitude E/sub 1/sup(pv) itself weakly depend on the shape of the one-electron potential provided the binding energies of the valence states are reproduced accurately. Furthermore it turns out that because of a compensation mechanism, the parity-violating transition is induced by the radiation field outside the ion core region where the screening can be described simply in terms of the measurable cesium ion polarizability. Our results are then used to extract, from the Ecole Normale Superieure experiment, a value of the weak charge Qsub(w)= -57.1+-9.4 (r.m.s. statistical deviation) +-4.7 (systematic uncertainty). This number is to be compared with the prediction of the Weinberg-Salam model with electro-weak radiative corrections: Qsub(w)=-68.6+-3.0.

  3. Imaging the heliosphere using neutral atoms from solar wind energy down to 15 eV

    Energy Technology Data Exchange (ETDEWEB)

    Galli, A.; Wurz, P. [Physics Institute, University of Bern, Bern 3012 (Switzerland); Fuselier, S. A.; McComas, D. J. [Southwest Research Institute, San Antonio, TX 78228 (United States); Bzowski, M.; Sokół, J. M.; Kubiak, M. A. [Space Research Centre, Polish Academy of Sciences, Warsaw 00-716 (Poland); Möbius, E. [University of New Hampshire, Durham, NH 03824 (United States)

    2014-11-20

    We study the spatial and temporal distribution of hydrogen energetic neutral atoms (ENAs) from the heliosheath observed with the IBEX-Lo sensor of the Interstellar Boundary EXplorer (IBEX) from solar wind energies down to the lowest available energy (15 eV). All available IBEX-Lo data from 2009 January until 2013 June were included. The sky regions imaged when the spacecraft was outside of Earth's magnetosphere and when the Earth was moving toward the direction of observation offer a sufficient signal-to-noise ratio even at very low energies. We find that the ENA ribbon—a 20° wide region of high ENA intensities—is most prominent at solar wind energies whereas it fades at lower energies. The maximum emission in the ribbon is located near the poles for 2 keV and closer to the ecliptic plane for energies below 1 keV. This shift is an evidence that the ENA ribbon originates from the solar wind. Below 0.1 keV, the ribbon can no longer be identified against the globally distributed ENA signal. The ENA measurements in the downwind direction are affected by magnetospheric contamination below 0.5 keV, but a region of very low ENA intensities can be identified from 0.1 keV to 2 keV. The energy spectra of heliospheric ENAs follow a uniform power law down to 0.1 keV. Below this energy, they seem to become flatter, which is consistent with predictions. Due to the subtraction of local background, the ENA intensities measured with IBEX agree with the upper limit derived from Lyα observations.

  4. Energetic neutral atom and interstellar flow observations with IBEX: Implications for the global heliosphere

    Science.gov (United States)

    Schwadron, N. A.; McComas, D. J.; Christian, E. R.; Desai, M. I.; Funsten, H. O.; Fuselier, S. A.; Moebius, E.; Reno, M.; Scherrer, J.; Zirnstein, E.

    2016-03-01

    Since launch in Oct. 2008, IBEX, with its two energetic neutral atom (ENA) cameras, has provided humankind with the first-ever global images of the complex boundary separating the heliosphere from the local interstellar medium (LISM). IBEX's energy-resolved all-sky maps, collected every six months, are yielding remarkable new insights into the heliospheres structure as it is shaped by the combined forces of the local interstellar flow, the local interstellar magnetic field (LISMF), and the evolving solar wind. IBEX has also acquired the first images of ENAs backscattered from the surface of the moon as well as global images of the magnetospheric response to solar wind disturbances. IBEX thus addresses all three Heliophysics science objectives set forth in the 2014 Science Plan for NASAs Science Mission Directorate (SMD) as well as the goals in the recent Solar and Space Physics Decadal Survey (NRC 2012). In addition, with the information it provides on the properties of the LISM and the LISMF, IBEX represents a unique bridge between heliophysics and astrophysics, and fills in critical knowledge for understanding the habitability of exoplanetary systems and the future habitability of Earth and the solar system. Because of the few-year time lag due to solar wind and ENA transport, IBEX observed the solar wind/ LISM interaction characteristic of declining phase/solar minimum conditions. In the continuing mission, IBEX captures the response of the interstellar boundaries to the changing structure of the solar wind in its transition toward the "mini" solar maximum and possibly the decline into the next solar minimum. The continuing IBEX mission affords never-to-be-repeated opportunities to coordinate global imaging of the heliospheric boundary with in-situ measurements by the Voyagers as they pass beyond the heliopause and start to directly sample the LISM.

  5. Separation of the IBEX Ribbon from the Globally Distributed Energetic Neutral Atom Flux

    Science.gov (United States)

    Schwadron, N. A.; Allegrini, F.; Bzowski, M.; Christian, E. R.; Crew, G. B.; Dayeh, M. A.; Demajistre, R.; Frisch, P. C.; Funsten, H. O.; Fuselier, S. A.; Goodrich, K. A.; Gruntman, M.; Janzen, P. H.; Kucharek, H.; Livadiotis, G.; McComas, D. J.; Moebius, E.; Prested, C. L.; Reisenfeld, D. B.; Reno, M. L.; Roelof, E. C.; Siegel, J. E.

    2010-12-01

    The Interstellar Boundary Explorer (IBEX) Mission observes a remarkable feature, the IBEX ribbon. This very narrow ~20° wide feature has energetic neutral atom (ENA) flux ~2-3 times the ENA flux that is globally distributed over other portions of the IBEX maps. Here, we separate ENA emissions in the ribbon from the globally distributed flux by applying a mask over the ribbon and regions where ENAs are produced from sources other than the heliosphere. We then solve for the globally distributed flux using two distinct methods: (1) an interpolation scheme and (2) a decomposition based on real-valued spherical harmonics. Our analysis shows that the energy spectrum and the spatial distribution of the ribbon are distinct from the surrounding globally distributed flux. The ribbon energy spectrum exhibits a knee between ~1 and 4 keV, and the angular distribution transverse to the ribbon is approximately independent of energy. In contrast, the globally distributed flux does not show a clear knee, and more closely conforms to a power-law over much of the sky. The slope of the power-law steepens from the nose to tail, suggesting a weaker termination shock toward the tail as compared to the nose. Both the slope in the energy distribution of the globally distributed flux and the knee in the energy distribution of the ribbon are ordered by latitude. Thus, we develop several methods to separate the ribbon from the globally distributed ENA flux in the maps observed by IBEX. Our analysis shows that the IBEX ribbon is distinct not only in its spatial distribution, but also its energy distribution, which suggests that the source plasma populations of the ribbon and globally distributed flux are produced via a distinct physical process.

  6. Survival probability and energy modification of hydrogen Energetic Neutral Atoms on their way from the termination shock to Earth orbit

    OpenAIRE

    Bzowski, M.

    2008-01-01

    Context: With the forthcoming launch of a NASA SMEX mission IBEX devoted to imaging of heliospheric interface by in-situ detection of Energetic Neutral Atoms (ENA) an important issue becomes recognizing of transport of these atoms from the termination shock of the solar wind to Earth orbit. Aims: Investigate modifications of energy and of survival probability of the H ENA detectable by IBEX (0.01 -- 6 keV) between the termination shock and Earth orbit taking into account the influence of the ...

  7. Observation of the distribution of heavy neutral atoms in the IBEX-Lo all-sky maps

    Science.gov (United States)

    Park, J.; Kucharek, H.; Moebius, E.

    2014-12-01

    We investigate the spatial distribution of heavy energetic neutral atoms, mostly oxygen and neon, in the sky maps taken with the Interstellar Boundary Explorer (IBEX) in 2009 - 2011. The IBEX-Lo sensor, one of two highly sensitive single-pixel cameras on the IBEX spacecraft, measures neutral particles within an energy range from 0.01 to 2 keV. In the time-of-flight detector of IBEX-Lo these neutral atoms can be identified as hydrogen or heavier atoms, such as oxygen. These measurements have provided all-sky maps of neutral hydrogen and oxygen. The dominant feature in these maps is the interstellar oxygen and neon gas flow. Its peak location is approximately consistent with the interstellar helium gas flow (Möbius et al., 2009, Science, 326, 969). The flow distribution is distributed over 210° - 240° ecliptic longitude and -6° - 12° ecliptic latitude. Another prominent feature in the oxygen sky maps at 0.2 to 0.8 keV is an extended tail of the oxygen signal toward lower longitude and higher positive latitude (180° - 210° ecliptic longitude and 0° - 24° ecliptic latitude). The measured peak rates in the extended tail is 3 - 5% of the maximum count rate in the primary oxygen and neon gas flow, but is four times higher than any other surrounding oxygen signals. The extended tail may indicate the secondary component of the interstellar oxygen, which is likely generated by charge exchange between local O+ ions and interstellar neutral H in the outer heliosheath. In this poster, we will discuss these two most prominent features in the oxygen sky maps and their implications for the source and the mechanism generating an extended tail in the oxygen signal.

  8. Sensitive Detection of Individual Neutral Atoms in a Strong Coupling Cavity QED System

    Institute of Scientific and Technical Information of China (English)

    ZHANG Peng-Fei; ZHANG Yu-Chi; LI Gang; DU Jin-Jin; ZHANG Yan-Feng; GUO Yan-Qiang; WANG Jun-Min; ZHANG Tian-Cai; LI Wei-Dong

    2011-01-01

    We experimentally demonstrate real-time detection of individual cesium atoms by using a high-finesse optical micro-cavity in a strong coupling regime.A cloud of cesium atoms is trapped in a magneto-optical trap positioned at 5 mm above the micro-cavity center.The atoms fall down freely in gravitation after shutting off the magnetooptical trap and pass through the cavity.The cavity transmission is strongly affected by the atoms in the cavity, which enables the micro-cavity to sense the atoms individually.We detect the single atom transits either in the resonance or various detunings.The single atom vacuum-Rabi splitting is directly measured to be Ω = 2π × 23.9 MHz.The average duration of atom-cavity coupling of about 110μs is obtained according to the probability distribution of the atom transits.%@@ We experimentally demonstrate real-time detection of individual cesium atoms by using a high-finesse optical micro-cavity in a strong coupling regime.A cloud of cesium atoms is trapped in a magneto-optical trap positioned at 5mm above the micro-cavity center.The atoms fall down freely in gravitation after shutting off the magnetooptical trap and pass through the cavity.The cavity transmission is strongly affected by the atoms in the cavity, which enables the micro-cavity to sense the atoms individually.We detect the single atom transits either in the resonance or various detunings.The single atom vacuum-Rabi splitting is directly measured to be Ω=2π×23.9 MHz.The average duration of atom-cavity coupling of about 110μs is obtained according to the probability distribution of the atom transits.

  9. Development of a high dynamic range spectroscopic system for observation of neutral hydrogen atom density distribution in Large Helical Device core plasma

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, K., E-mail: fujii@me.kyoto-u.ac.jp; Atsumi, S.; Watanabe, S.; Shikama, T.; Hasuo, M. [Department of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto University, Kyoto 606-8540 (Japan); Goto, M.; Morita, S. [National Institute for Fusion Science, Toki 509-5292 (Japan)

    2014-02-15

    We report development of a high dynamic range spectroscopic system comprising a spectrometer with 30% throughput and a camera with a low-noise fast-readout complementary metal-oxide semiconductor sensor. The system achieves a 10{sup 6} dynamic range (∼20 bit resolution) and an instrumental function approximated by a Voigt profile with Gauss and Lorentz widths of 31 and 0.31 pm, respectively, for 656 nm light. The application of the system for line profile observations of the Balmer-α emissions from high temperature plasmas generated in the Large Helical Device is also presented. In the observed line profiles, emissions are detected in far wings more than 1.0 nm away from the line center, equivalent to neutral hydrogen atom kinetic energies above 1 keV. We evaluate atom density distributions in the core plasma by analyzing the line profiles.

  10. Survival probability and energy modification of hydrogen Energetic Neutral Atoms on their way from the termination shock to Earth orbit

    CERN Document Server

    Bzowski, M

    2008-01-01

    Contect: With the forthcoming launch of a NASA SMEX mission IBEX devoted to imaging of heliospheric interface by in-situ detection of Energetic Neutral Atoms (ENA) an important issue becomes recognizing of transport of these atoms from the termination shock of the solar wind to Earth orbit. Aims: Investigate modifications of energy and of survival probability of the H ENA detectable by IBEX (0.01 -- 6 keV) between the termination shock and Earth orbit taking into account the influence of the variable and anisotropic solar wind and solar EUV radiation. Methods: Energy change of the atoms is calculated by numerical simulations of orbits of the H ENA atoms from ~100 AU from the Sun down to Earth orbit, taking into account solar gravity and Lyman-$\\alpha$ radiation pressure, which is variable in time and depends on radial velocity of the atom. To calculate survival probabilities of the atoms against onization, a detailed 3D and time-dependent model of H ENA ionization based on observations of the solar wind and E...

  11. Understanding Molecular Ion-Neutral Atom Collisions for the Production of Ultracold Molecular Ions

    Science.gov (United States)

    2016-06-06

    ions affords many of the benefits of ultracold neutral molecules, while significantly reducing experimental complexity – e.g. large trap depths, long...affords many of the benefits of ultracold neutral molecules, while significantly reducing experimental complexity – e.g. large trap depths, long trap...cooling collisions. As shown in Fig . 2, which plots the results of a photodissociative thermometry measurement, the molecular ions have

  12. Iterative inversion of global magnetospheric information from energy neutral atom (ENA) images recorded by the TC-2/NUADU instrument

    Institute of Scientific and Technical Information of China (English)

    S.; MCKENNA-LAWLOR; S.; BARABASH; J.; BALAZ

    2008-01-01

    A method is presented for retrieving the magnetospheric ion distribution from En-ergetic Neutral Atom (ENA) measurements made by the NUADU instrument on the TC-2 spacecraft. Based on the already well-established method of constrained lin-ear inversion, an iterance technique suitable for the low count ENA measurements has been developed which is tolerant of the noise background. By the iterance technique, it is possible for the first time to simultaneously retrieve the magneto-spheric ion distribution and the exospheric neutral density, and further to recover global ENA emissions in three dimensions. The technique is applied to a repre-sentative ENA image recorded in energy channel 2 (protons: 50―81 keV) of the NUADU instrument during a major geomagnetic storm and it is, thereby, shown that the retrieval method developed provides a useful tool for extracting ion distribution information from ENA data.

  13. Iterative inversion of global magnetospheric information from energy neutral atom (ENA)images recorded by the TC-2/NUADU instrument

    Institute of Scientific and Technical Information of China (English)

    LU Li; S. MCKENNA-LAWLOR; S. BARABASH; J. BALAZ; LIU ZhenXing; SHEN Chao; CAO JinBin; ANG ChaoLing

    2008-01-01

    A method is presented for retrieving the magnetospheric ion distribution from En-ergetic Neutral Atom (ENA) measurements made by the NUADU instrument on the TC-2 spacecraft. Based on the already well-established method of constrained lin-ear inversion, an iterance technique suitable for the low count ENA measurements has been developed which is tolerant of the noise background. By the iterance technique, it is possible for the first time to simultaneously retrieve the magneto-spheric ion distribution and the exospheric neutral density, and further to recover global ENA emissions in three dimensions. The technique is applied to a repre-sentative ENA image recorded in energy channel 2 (protons: 50-81 keV) of the NUADU instrument during a major geomagnetic storm and it is, thereby, shown that the retrieval method developed provides a useful tool for extracting ion distribution information from ENA data.

  14. van der Waals interaction of a neutral atom with the surface of a metal or dielectric nanosphere

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Regine; Chormaic, Sile Nic [Photonics Centre, Tyndall National Institute, Prospect Row, Cork (Ireland); Minogin, Vladimir G, E-mail: s.nicchormaic@ucc.ie [Institute of Spectroscopy Russ. Ac. of Sciences, 142190 Troitsk, Moscow region (Russian Federation)

    2011-01-14

    We analyse the van der Waals interaction of a neutral atom with the internal and external surfaces of either a metal or dielectric nanosphere. We derive closed analytical equations for the van der Waals interaction energy using an electrostatic approximation and show that the energy increases or decreases as a function of the atom's distance from the surface, depending on the surface curvature. For concave spherical surfaces, the van der Waals energy can increase by up to a factor of 6, while for convex surfaces it decreases by as much as a factor of 2, when compared to that obtained for a flat surface. The derived analytical equations are very simple and can be used for a comparison between theory and experimental measurements of the van der Waals constant, C{sub 3}.

  15. Mutual Neutralization of Atomic Rare-Gas Cations (Ne+, Ar+, Kr+, Xe+) with Atomic Halide Anions (Cl-, Br-, I-)

    Science.gov (United States)

    2015-01-07

    occur at intersections of the initial ionic potential curve and those describing the interaction between the atoms in their fi- nal states, as in...reactions, the halogen product is formed in excited states with sufficient energy to autoionize to form X+ + e−, Rg+ +X− → Rg +X∗, (3a) → Rg +X+ + e−. (3b...me- ters. The liquid reagents, CCl4 and CF2Br2, are purified via freeze-pump-thaw cycles prior to mixture preparation. The absolute electron density

  16. A Molecular Dynamics of Cold Neutral Atoms Captured by Carbon Nanotube Under Electric Field and Thermal Effect as a Selective Atoms Sensor.

    Science.gov (United States)

    Santos, Elson C; Neto, Abel F G; Maneschy, Carlos E; Chen, James; Ramalho, Teodorico C; Neto, A M J C

    2015-05-01

    Here we analyzed several physical behaviors through computational simulation of systems consisting of a zig-zag type carbon nanotube and relaxed cold atoms (Rb, Au, Si and Ar). These atoms were chosen due to their different chemical properties. The atoms individually were relaxed on the outside of the nanotube during the simulations. Each system was found under the influence of a uniform electric field parallel to the carbon nanotube and under the thermal effect of the initial temperature at the simulations. Because of the electric field, the cold atoms orbited the carbon nanotube while increasing the initial temperature allowed the variation of the radius of the orbiting atoms. We calculated the following quantities: kinetic energy, potential energy and total energy and in situ temperature, molar entropy variation and average radius of the orbit of the atoms. Our data suggest that only the action of electric field is enough to generate the attractive potential and this system could be used as a selected atoms sensor.

  17. Combining red- and blue-detuned optical traps to form a Lamb-Dicke trap for a single neutral atom

    CERN Document Server

    He, Xiaodong; Wang, Jin; Zhan, Mingsheng

    2010-01-01

    We propose and demonstrate a scheme for strongly radially confining a single neutral atom in a bichromatic far-off resonance optical dipole trap(BFORT) . BFORT is composed of a blue-detuned Laguerre-Gaussian $LG^1_ 0$ beam and a red-detuned Gaussian beam. The trapping radial dimension of a single atom trapped in the Gaussian FORT can be greatly compressed by imposing a blue-detuned Laguerre-Gaussian $LG^1_ 0$ beam with moderate potential depth. By modulating the potential depth of the Gaussian FORT we observed that the resonant and parametric excitation of the oscillatory motion of a single atom in this BFORT and obtained the oscillation frequency that well fits prediction from the theoretical model. The frequency measurement shows that effective trapping dimension can be greatly sharper than that diffraction limited of microscopic objective we used. Then we show that the excess scattering rate due to imposing blue detuned light can be eliminated when single atoms is close to ground-state theoretically. So BF...

  18. Efficient loading of a single neutral atom into an optical microscopic tweezer

    Institute of Scientific and Technical Information of China (English)

    何军; 刘贝; 刁文婷; 王杰英; 靳刚; 王军民

    2015-01-01

    A single atom in a magneto–optical trap (MOT) with trap size (hundreds of micrometers) can be transferred into an optical microscopic tweezer with a probability of∼100%. The ability to transfer a single atom into two traps back and forth allows us to study the loading process. The loading probability is found to be insensitive to the geometric overlap of the MOT and the tweezer. It is therefore possible to perform simultaneously loading of a single atom into all sites of the tweezer array for many qubits. In particular, we present a simulation of the one-dimensional and two-dimensional arrays of an optical microscopic tweezer. We find the same qualitative behavior for all of the trap parameters.

  19. Efficient loading of a single neutral atom into an optical microscopic tweezer

    Science.gov (United States)

    He, Jun; Liu, Bei; Diao, Wen-Ting; Wang, Jie-Ying; Jin, Gang; Wang, Jun-Min

    2015-04-01

    A single atom in a magneto-optical trap (MOT) with trap size (hundreds of micrometers) can be transferred into an optical microscopic tweezer with a probability of ~ 100%. The ability to transfer a single atom into two traps back and forth allows us to study the loading process. The loading probability is found to be insensitive to the geometric overlap of the MOT and the tweezer. It is therefore possible to perform simultaneously loading of a single atom into all sites of the tweezer array for many qubits. In particular, we present a simulation of the one-dimensional and two-dimensional arrays of an optical microscopic tweezer. We find the same qualitative behavior for all of the trap parameters. Project supported by the National Major Scientific Research Program of China (Grant No. 2012CB921601) and the National Natural Science Foundation of China (Grant Nos. 61205215, 11274213, and 61475091).

  20. Photoionization of neutral atoms by X waves carrying orbital angular momentum

    Science.gov (United States)

    Müller, Robert A.; Seipt, Daniel; Beerwerth, Randolf; Ornigotti, Marco; Szameit, Alexander; Fritzsche, Stephan; Surzhykov, Andrey

    2016-10-01

    In contrast to plane waves, twisted or vortex beams have a complex spatial structure. Both their intensity and energy flow vary within the wave front. Beyond that, polychromatic vortex beams, such as X waves, have a spatially dependent energy distribution. We propose a method to measure this (local) energy spectrum. The method is based on the measurement of the energy distribution of photoelectrons from alkali-metal atoms. On the basis of our fully relativistic calculations, we argue that even ensembles of atoms can be used to probe the local energy spectrum of short twisted pulses.

  1. A neutral atom frequency reference in the deep UV with 10^(-15) range uncertainty

    CERN Document Server

    McFerran, J J; Mejri, S; Di Manno, S; Zhang, W; Guéna, J; Coq, Y Le; Bize, S

    2012-01-01

    We present an assessment of the (6s^{2})1S0 -> (6s7s)3P0 clock transition frequency in 199Hg with an uncertainty reduction of nearly three orders of magnitude and demonstrate an atomic quality factor, Q, of ~10^(14). The 199Hg atoms are confined in a vertical lattice trap with light at the newly determined magic wavelength of 362.5697 +/-0.0011 nm and at a lattice depth of 20Er. The atoms are loaded from a single stage magneto-optical trap with cooling light at 253.7 nm. The high Q factor is obtained with an 80 ms Rabi pulse at 265.6 nm. The frequency of the clock transition is found to be 1 128 575 290 808 162.0 +/-6.4 (sys.) +/-0.3 (stat.) Hz (fractional uncertainty = 5.7x10^(-15)). Neither an atom number nor second order Zeeman dependence have yet to be detected. Only three laser wavelengths are used for the cooling, lattice trapping, probing and detection.

  2. Ellipticity dependence of neutral Rydberg excitation of atoms in strong laser fields

    Science.gov (United States)

    Zhao, Lei; Dong, Jingwei; Lv, Hang; Yang, Tianxiang; Lian, Yi; Jin, Mingxing; Xu, Haifeng; Ding, Dajun; Hu, Shilin; Chen, Jing

    2016-11-01

    Rydberg state excitation (RSE) of different atoms in elliptically polarized strong 800 nm laser fields is investigated experimentally, and the results are compared with calculations of the strong-field approximation (SFA) model and the semiclassical model. It is observed that the RSE probability declines with increasing laser ellipticity for all of the He, Ar, and Kr atoms. While the measured ellipticity dependence of He RSE is very consistent with the predictions of both the SFA and semiclassical calculations, the width of the ellipticity dependence for Ar and Kr atoms is wider than that of the SFA model but closer to the semiclassical calculations. Analysis indicates that unlike a tunneling-plus-rescattering process, the decline of the RSE yield with increasing ellipticity can be attributed to a decrease of electrons with low kinetic energy that could be captured in the Rydberg states by the Coulomb potential. It indicates that the atomic RSE process could be related to the very low or near-zero energy structure in the photoelectron spectrum in strong laser fields, which would stimulate further experimental and theoretical studies to reveal their underlying mechanisms.

  3. 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

  4. 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

  5. THE COMPARASION BETWEEN EPISTOMOLOGICAL ANALYZE OF ATOM CONCEPT AND STUDENTS' MISCONCEPTIONS ON THE TOPIC

    OpenAIRE

    Özgür, Sami

    2007-01-01

    The aim of this research is to establish a link and/or similarity, if there is any, between the misconceptions with epistemological origin of the students on atom concept and the epistemological obstacles which have been encountered since early times on atom concept. To accomplish this aim a misconceptions diagnostic test composed of 5 open-ended questions of which reliability and validity studies had been done administered to 105 primary school students. Moreover, detailed data on the topic ...

  6. Structural analyses at pseudo atomic resolution of Chikungunya virus and antibodies show mechanisms of neutralization.

    Science.gov (United States)

    Sun, Siyang; Xiang, Ye; Akahata, Wataru; Holdaway, Heather; Pal, Pankaj; Zhang, Xinzheng; Diamond, Michael S; Nabel, Gary J; Rossmann, Michael G

    2013-04-02

    A 5.3 Å resolution, cryo-electron microscopy (cryoEM) map of Chikungunya virus-like particles (VLPs) has been interpreted using the previously published crystal structure of the Chikungunya E1-E2 glycoprotein heterodimer. The heterodimer structure was divided into domains to obtain a good fit to the cryoEM density. Differences in the T = 4 quasi-equivalent heterodimer components show their adaptation to different environments. The spikes on the icosahedral 3-fold axes and those in general positions are significantly different, possibly representing different phases during initial generation of fusogenic E1 trimers. CryoEM maps of neutralizing Fab fragments complexed with VLPs have been interpreted using the crystal structures of the Fab fragments and the VLP structure. Based on these analyses the CHK-152 antibody was shown to stabilize the viral surface, hindering the exposure of the fusion-loop, likely neutralizing infection by blocking fusion. The CHK-9, m10 and m242 antibodies surround the receptor-attachment site, probably inhibiting infection by blocking cell attachment. DOI:http://dx.doi.org/10.7554/eLife.00435.001.

  7. Microtraps for neutral atoms using superconducting structures in the critical state

    CERN Document Server

    Emmert, Andreas; Brune, Michel; Raimond, Jean-Michel; Haroche, Serge; Nogues, Gilles

    2009-01-01

    Recently demonstrated superconducting atom-chips provide a platform for trapping atoms and coupling them to solid-state quantum systems. Controlling these devices requires a full understanding of the supercurrent distribution in the trapping structures. For type-II superconductors, this distribution is hysteretic in the critical state due to the partial penetration of the magnetic field in the thin superconducting film through pinned vortices. We report here an experimental observation of this memory effect. Our results are in good agreement with the redictions of the Bean model of the critical state without adjustable parameters. The memory effect allows to write and store permanent currents in micron-sized superconducting structures and paves the way towards new types of engineered trapping potentials.

  8. Microtraps for neutral atoms using superconducting structures in the critical state

    Science.gov (United States)

    Emmert, A.; Lupaşcu, A.; Brune, M.; Raimond, J.-M.; Haroche, S.; Nogues, G.

    2009-12-01

    Recently demonstrated superconducting atom chips provide a platform for trapping atoms and coupling them to solid-state quantum systems. Controlling these devices requires a full understanding of the supercurrent distribution in the trapping structures. For type-II superconductors, this distribution is hysteretic in the critical state due to the partial penetration of the magnetic field in the thin superconducting film through pinned vortices. We report here an experimental observation of this memory effect. Our results are in good agreement with the predictions of the Bean model of the critical state without adjustable parameters. The memory effect allows to write and store permanent currents in micron-sized superconducting structures and paves the way toward engineered trapping potentials.

  9. Thomson spectrometer-microchannel plate assembly calibration for MeV-range positive and negative ions, and neutral atoms

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, R. [Centre for Plasma Physics, School of Mathematics and Physics, The Queen' s University of Belfast, Belfast BT7 1NN (United Kingdom); Abicht, F.; Braenzel, J.; Priebe, G.; Schnuerer, M. [Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin (Germany); Borghesi, M.; Ter-Avetisyan, S. [Centre for Plasma Physics, School of Mathematics and Physics, The Queen' s University of Belfast, Belfast BT7 1NN (United Kingdom); ELI-Beamlines Project, Institute of Physics of the ASCR, Na Slovance 2, 18221 Prague (Czech Republic); Nickles, P. V. [WCU Department of Nanobio Materials and Electronics, GIST, Gwangju 500-712 (Korea, Republic of)

    2013-05-15

    We report on the absolute calibration of a microchannel plate (MCP) detector, used in conjunction with a Thomson parabola spectrometer. The calibration delivers the relation between a registered count numbers in the CCD camera (on which the MCP phosphor screen is imaged) and the number of ions incident on MCP. The particle response of the MCP is evaluated for positive, negative, and neutral particles at energies below 1 MeV. As the response of MCP depends on the energy and the species of the ions, the calibration is fundamental for the correct interpretation of the experimental results. The calibration method and arrangement exploits the unique emission symmetry of a specific source of fast ions and atoms driven by a high power laser.

  10. A gated Thomson parabola spectrometer for improved ion and neutral atom measurements in intense laser produced plasmas

    Science.gov (United States)

    Tata, Sheroy; Mondal, Angana; Sarkar, Soubhik; Lad, Amit D.; Krishnamurthy, M.

    2017-08-01

    Ions of high energy and high charge are accelerated from compact intense laser produced plasmas and are routinely analysed either by time of flight or Thomson parabola spectrometry. At the highest intensities where ion energies can be substantially large, both these techniques have limitations. Strong electromagnetic pulse noise jeopardises the arrival time measurement, and a bright central spot in the Thomson parabola spectrometer affects the signal to noise ratio of ion traces that approach close to the central spot. We present a gated Thomson parabola spectrometer that addresses these issues and provides an elegant method to improvise ion spectrometry. In addition, we demonstrate that this method provides the ability to detect and measure high energy neutral atoms that are invariably present in most intense laser plasma acceleration experiments.

  11. Third-order Douglas-Kroll self-consistent field energies for the neutral atoms H to Uuo.

    Science.gov (United States)

    Saito, Shiro L

    2009-02-21

    Third-order Douglas-Kroll self-consistent field (DK3-SCF) calculations with a finite-nucleus model were carried out for the neutral atoms H to Uuo, and DK3-SCF energies were obtained for them. The basis set used was the B-spline set. The parameters of the B-spline set were determined so as to reproduce the SQR-SCF limit energies given by Gaussian-type functions (GTFs). The SQR-SCF is a self-consistent field calculation with a simplified first-order Douglas-Kroll Hamiltonian (the "SQR" Hamiltonian) and can be carried out exactly with GTFs. The DK3-SCF energies given by this B-spline set should be highly accurate. A comparison is made with the DK3-SCF energies of Nakajima and Hirao [J. Chem. Phys. 116, 8270 (2002).

  12. Removal of carbon and nanoparticles from lithographic materials by plasma assisted cleaning by metastable atom neutralization (PACMAN)

    Science.gov (United States)

    Lytle, W. M.; Lofgren, R. E.; Surla, V.; Neumann, M. J.; Ruzic, D. N.

    2010-04-01

    System cleanliness is a major issue facing the lithographic community as the prospects of integrating EUV lithography into integrated circuit manufacturing progress. Mask cleanliness, especially of particles in the sub-micron range, remains an issue for the implementation of EUV lithography since traditional mask cleaning processes are limited in their ability to remove nanometer scale contaminants. The result is lower wafer throughput due to errors in pattern transfer to the wafer from the particulate defects on the mask. Additionally, carbon contamination and growth on the collector optics due to energetic photon interactions degrade the mirror and shortens its functional life. Plasma cleaning of surfaces has been used for a variety of applications in the past, and now is being extended to cleaning surfaces for EUV, specifically the mask and collector optics, through a process developed in the Center for Plasma-Material Interactions (CPMI) called Plasma Assisted Cleaning by Metastable Atom Neutralization (PACMAN). This process uses energetic neutral atoms (metastables) in addition to a high-density plasma (Te ~ 3 eV and ne ~ 1017 m-3) to remove particles. The PACMAN process is a completely dry process and is carried out in a vacuum which makes it compatible with other EUV related processing steps. Experiments carried out on cleaning polystyrene latex (PSL) nanoparticles (30 nm to 500 nm) on silicon wafers, chrome coated mask blanks, and EUV mask blanks result in 100 % particle removal with a helium plasma and helium metastables. Removal rates greater than 20 nm/min have been achieved for PSL material. Similar removal rates have been achieved for the PACMAN cleaning of carbon from silicon wafers (simulating collector optic material) with 100% removal with helium plasma and helium metastables. The PACMAN cleaning technique has not caused any damage to the substrate type being cleaned either through roughening or surface sputtering. Current results of cleaning

  13. Energetic Neutral Atom (ENA) intensity gradients in the heliotail during year 2003, using Cassini/INCA measurements

    Science.gov (United States)

    Dialynas, K.; Krimigis, S. M.; Mitchell, D. G.; Roelof, E. C.

    2015-01-01

    In the present study we use all-sky energy-resolved (5-55 keV) energetic neutral atom (ENA) maps obtained by the Ion and Neutral CAmera (INCA) on board Cassini during the time period DOY 265/2003 to 268/2003, to investigate the properties of the peak-to-basin ENA emissions in the direction of the heliotail. Our conclusions can be summarized as follows: (1) a relatively smooth boundary (called "transition region") between the very low (basin) and high (tail) ENA emissions from the heliosheath, with a spatial width of ~30° deg in ecl. longitude, that no theory had predicted to date, is identified in the energy range of 5-55 keV; (2) the ENA intensity gradient in this transition region is almost invariant as a function of both ecl. Latitude and energy, with an average value of ~2.4% per degree; (3) the deduced partial plasma pressure distributions in the 5-55 keV energy range are consistent with the ENA intensity distributions in the same energy range, while the ENA intensity gradient translates to a corresponding partial pressure gradient that occurs in the transition region; and (4) this partial pressure gradient is possibly not consistent with a tail magnetic field configuration that is similar to the measured magnetic fields by the Voyagers in the nose hemisphere.

  14. Evolution of energetic neutral atom spectra as measured by the Interstellar Boundary Explorer during its first seven years

    Science.gov (United States)

    Dayeh, Maher A.; Heerikhuisen, Jacob; McComas, David; Schwadron, Nathan; Desai, Mihir; Zirnstein, Eric J.

    2016-07-01

    The Interstellar Boundary Explorer (IBEX) mission continues to provide remote Energetic Neutral Atom (ENA) measurements produced by charge exchange between energetic protons and interstellar neutrals at the edge of our heliosphere. Using the first seven years of IBEX-Hi ENA measurements (January 2009 through December 2015), we examine the evolution of the spectral slopes in four different energy bands, namely, ˜0.7-1.1 keV, ˜1.1-1.7 keV, ˜1.7-2.7 keV, and ˜2.7-4.3 keV, across different regions of the sky. Results show that spectral slopes at each energy band are characterized with unique distribution properties (e.g., width, shape, and mode), which vary in time at different rates and in both directions (distribution modes increase or decrease). We attempt to explain these results in context of ENA source regions, solar wind temporal variations, and changes in the heliosheath thickness and its plasma properties. These results provide insights into ENA production mechanisms, properties of their plasma progenitors, and how they relate to changes in the solar wind.

  15. The effect of new interstellar medium parameters on the heliosphere and energetic neutral atoms from the interstellar boundary

    Energy Technology Data Exchange (ETDEWEB)

    Heerikhuisen, J.; Zirnstein, E. J.; Pogorelov, N. V.; Zank, G. P. [Department of Space Science and Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Funsten, H. O., E-mail: jacob.heerikhuisen@uah.edu [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2014-03-20

    We present new results from three-dimensional simulations of the solar wind interaction with the local interstellar medium (LISM) using recent observations by NASA's Interstellar Boundary EXplorer (IBEX) mission estimates of the velocity and temperature of the LISM. We investigate four strengths of the LISM magnetic field, from 1 to 4 μG, and adjust the LISM proton and hydrogen densities so that the distance to the termination shock (TS) in the directions of the Voyager spacecraft is just below 90 AU, and the density of hydrogen at the TS is close to 0.09 cm{sup –3} in the nose direction. The orientation of the magnetic field is chosen to point toward the center of the ribbon of enhanced energetic neutral atom (ENA) flux seen in the IBEX data. Our simulations show that the plasma and neutral properties in the outer heliosheath vary considerably as a function of the LISM magnetic field strength. We also show that the heliotail points downwind in all cases, though its structure is strongly affected by the external magnetic field. Comparison and consistency between the simulated ENA flux and the circularity of the ribbon as measured by IBEX are most consistent with a LISM magnetic field strength aligned with the center of the ribbon and a magnitude in the range 2.5-3 μG.

  16. Theory of cooperative fluorescence from products of reactions or collisions: Identical neutral atomic fragments

    Science.gov (United States)

    Kurizki, Gershon; Ben-Reuven, Abraham

    1987-07-01

    The time-resolved cooperative emission from a system of correlated neutral dissociation fragments, or molecular collision products in beams, is investigated. The investigation is focused on emission at large fragment separations (between 1 nm and a few emission wavelengths), exceeding the domain of short-range interactions within the reactive or collisional molecular complex. A master-equation approach is used to obtain a general expression for the cooperative emission rate, which consists of nonexponential decay factors multiplied by temporal ringing patterns. These features result from the time-dependent radiative coupling between the receding fragments; they depend in an essential manner on the initial electronic state of the parent molecular complex and its symmetry which determine the correlations between the fragments. In the model system of a pair of identical two-level fragments two cases are considered separately. (a) A single photon shared by the fragments, where the emission is initially superradiant or subradiant (radiation trapping), depending on the spin and inversion symmetry of the parent molecular system and of the nascent fragments. The ringing pattern depends on the electronic angular momentum state of the parent molecule and on the polarization of the emitted light. (Such a ringing has been observed recently by Grangier, Aspect, and Vigué [Phys. Rev. Lett. 54, 418 (1985)] in the emission of photodissociated Ca2.) (b) Two initially excited fragments, where the ringing pattern is of smaller amplitude, and is weakly dependent on the electronic angular momentum of the parent molecule. All the aforementioned cooperative features generally last until the fragments recede several radiation wavelengths away from each other. The application of this time-resolved analysis to various diagnostic problems is discussed, especially with regard to the identification of excited electronic states of the parent molecular complex, and the stereospecificity of the

  17. A modified fluorimetric neutral filter elution method for analyzing radiation-induced double strand break and repair.

    Science.gov (United States)

    Goutham, Venkatesh H; Kamalesh, Mumbrekar D; Guruprasad, Parashiva K; Vadhiraja, Manjunath B; Satyamoorthy, Kapaettu; Rao Bola Satish, Sadashiva

    2011-07-15

    Neutral filter elution assay is one of the methods used for detection of DNA double strand breaks (DSBs). However, it is laborious, expensive, and hazardous (radiolabeled precursors for DSB detection and scintillation counter for quantification), making it a less preferred method for DSB detection. In the present study, an attempt was made to improve the existing neutral filter elution assay by making use of fluorescent dye (PicoGreen) and microfiltration assembly for eluting the fragmented DNA, thereby reducing the cost and time required for the assay. We studied the effect of dye dilution, pH conditions, and cell number as a part of method standardization. X-ray dose-response and repair kinetics in lymphocytes as well as cell lines were studied for validating the sensitivity of the assay. A linear dose-response relationship for DSBs was observed at a cell number of 4×10(5)cells, a dye dilution of 500-fold, and at pH 10. Repair kinetics revealed a time-dependent repair of DSBs up to 360 min of posttreatment, indicating its usefulness in DSB repair studies. In conclusion, the present modified method is more efficient (in terms of cell number), cost effective, less time-consuming, and less hazardous compared to the existing method. Copyright © 2011 Elsevier Inc. All rights reserved.

  18. Imaging of neutral lipids by oil red O for analyzing the metabolic status in health and disease.

    Science.gov (United States)

    Mehlem, Annika; Hagberg, Carolina E; Muhl, Lars; Eriksson, Ulf; Falkevall, Annelie

    2013-06-01

    Excess lipid accumulation in peripheral tissues is a key feature of many metabolic diseases. Therefore, techniques for imaging and quantifying lipids in various tissues are important for understanding and evaluating the overall metabolic status of a research subject. Here we present a protocol that detects neutral lipids and lipid droplet (LD) morphology by oil red O (ORO) staining of sections from frozen tissues. The method allows for easy estimation of tissue lipid content and distribution using only basic laboratory and computer equipment. Furthermore, the procedure described here is well suited for the comparison of different metabolically challenged animal models. As an example, we include data on muscular and hepatic lipid accumulation in diet-induced and genetically induced diabetic mice. The experimental description presents details for optimal staining of lipids using ORO, including tissue collection, sectioning, staining, imaging and measurements of tissue lipids, in a time frame of less than 2 d.

  19. [Studies on cold resistance of hazel determined and analyzed by atomic absorption spectrometry].

    Science.gov (United States)

    Li, Xiu-Xia; Liu, Cheng-Cai; Zhang, Wei-Dong; Shao, Hong; Wu, Heng-Mei; Wang, Zhong; Yang, Yong-Nian; Li, Ji-Lin

    2010-06-01

    Using annual branch of hazel as the experimental materials, the K(+)-leakage and relative electric conductivity of three hazel species (six hazel clones) which had been treated with different low temperature were determined by electro-conductivity gauge and atomic absorption spectrometry. Regression models were established for low temperature to the K(+)-leakage or the relative electric conductivity of six hazel clones. The results showed that there was the same result of cold resistance for all clones using the two methods of comprehensive evaluation, and the indicator of K(+)-leakage rate determined by atomic absorption spectrometry can be used as a means of early identification of cold resistance of hazel clones. There were obvious differences among the clones in the ability of cold resistance. The order of the ability of cold resistance for the six hazel clones was C7R7 > Z-9-40 > C6R1 > CS2R1 > Z-9-22 > Z-9-30, and the order of the ability of cold resistance for the three hazel species was C. heterophylla > C. heterophyllax X (C. heterophylla X C. avellana) > C. heterophylla X C. avellana. The median lethal temperature of tissue for all clones is -26(-)-40 degrees "C.

  20. Spectral evolution of energetic neutral atom emissions at the heliospheric poles as measured by IBEX during its first three years

    Energy Technology Data Exchange (ETDEWEB)

    Dayeh, M. A.; Allegrini, F.; Desai, M. I.; Ebert, R. W.; Fuselier, S. A.; Livadiotis, G.; McComas, D. J.; Schwadron, N. A. [Southwest Research Institute, San Antonio, TX 78228 (United States); DeMajistre, R. [Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States); Janzen, P.; Reisenfeld, D. [University of Montana, Missoula, MT 59812 (United States); Siewert, M., E-mail: maldayeh@swri.edu [Institut für Astronomie der Universität Bonn, Abteilung f. Astrophysik und Extraterrestrische Forschung, Auf dem Hügel 71, D-53121 Bonn (Germany)

    2014-12-10

    The Interstellar Boundary Explorer (IBEX) mission continues to measure energetic neutral atom (ENA) emissions produced by charge exchange between solar wind (SW) protons and interstellar neutrals at the edge of our heliosphere. Using the first 3 yr of IBEX-Hi ENA measurements (2009-2011), we examined the spectral evolution of ∼0.5-6 keV ENAs at the polar regions (above 60°). We found the following: (1) pixels with a characteristic 'ankle' spectra (lower spectral index at higher energies) increase by ∼5% in 2010 and ∼10% in 2011 compared to 2009. (2) The averaged spectral index in 2011 is smaller than that of 2009. (3) The slope of the ENA spectrum above ∼1.7 keV is more variable than the slope below ∼1.7 keV. The lower spectral index at higher energies of the spectrum does not appear to be caused by an increase of the ENA production at these energies, but rather from a consistent decrease at lower energies. (4) The decrease in polar ENA fluxes does not correlate significantly with the averaged SW dynamic pressure, back-traced in time to 1 AU along the flow streamlines (originating between 10° and 30° for slow SW, and 60° and 80° for fast SW), assuming these are the respective conditions of ENA progenitors back in time. These results provide insights into the complexity of relating the slow and fast SW contributions to polar ENAs and shed light on how the solar output and the resulting change in the global heliospheric structure possibly affect the heliosheath (HS) populations.

  1. Initial Results from the Miniature Imager for Neutral Ionospheric Atoms and Magnetospheric Electrons (MINI-ME) on the FASTSAT Spacecraft

    Science.gov (United States)

    Collier, Michael R.; Rowland, Douglas; Keller, John W.; Chornay, Dennis; Khazanov, George; Herrero, Federico; Moore, Thomas E.; Kujawski, Joseph; Casas, Joseph C.; Wilson, Gordon

    2011-01-01

    The MINI-ME instrument is a collaborative effort between NASA's Goddard Space Flight Center (GSFC) and the U.S. Naval Academy, funded solely through GSFC Internal Research and Development (IRAD) awards. It detects neutral atoms from about 10 eV to about 700 eV (in 30 energy steps) in its current operating configuration with an approximately 10 degree by 360 degree field-of-view, divided into six sectors. The instrument was delivered on August 3, 2009 to Marshall Space Flight Center (MSFC) for integration with the FASTSAT-HSV01 small spacecraft bus developed by MSFC and a commercial partner, one of six Space Experiment Review Board (SERB) experiments on FASTSAT and one of three GSFC instruments (PISA and TTI being the other two). The FASTSAT spacecraft was launched on November 21, 2010 from Kodiak, Alaska on a Minotaur IV as a secondary payload and inserted into a 650 km, 72 degree inclination orbit, very nearly circular. MINI-ME has been collecting science data, as spacecraft resources would permit, in "optimal science mode" since January 20, 2011. In this presentation, we report initial science results including the potential first observations of neutral molecular ionospheric outflow. At the time of this abstract, we have identified 15 possible molecular outflow events. All these events occur between about 65 and 82 degrees geomagnetic latitude and most map to the auroral oval. The MINI-ME results provide an excellent framework for interpretation of the MILENA data, two instruments almost identical to MINI-ME that will launch on the VISIONS suborbital mission

  2. Solar wind He pickup ions as source of tens-of-keV/n neutral He atoms observed by the HSTOF/SOHO detector

    CERN Document Server

    Grzedzielski, S; Czechowski, A; Hilchenbach, M

    2013-01-01

    Context. The HSTOF instrument on board SOHO satellite measures since 1996, during periods of low solar activity, weak fluxes of He atoms of 28-58 keV/n (helium energetic neutral atoms - He ENA). The probable source region is the inner heliosheath. Aims. Understand the emission mechanism of He ENA based on knowledge of heliosheath spatial extent and plasma content resulting from Voyager 1 & 2 measurements in the period posterior to termination shock crossings. Methods. He ENA are generated by charge-exchange neutralization of energetic helium ions on interstellar neutral H and He. Energy spectra of helium ions in the heliosheath are calculated by following the evolution of their velocity distribution functions when carried by, and undergoing binary interactions with, plasma constituents of a background flow whose particle populations are modeled to approximately render post-termination shock Voyager data. Results. The observed HSTOF He ENA form a higher energy part of general heliospheric He ENA fluxes and...

  3. Analyzing Capabilities of Commercial and Open-Source Routers to Implement Atomic BGP

    Directory of Open Access Journals (Sweden)

    A. Cvjetić

    2010-06-01

    Full Text Available The paper analyzes implementations of BGP protocol on commercial and open-source routers and presents how some existing BGP extensions and routing table isolation mechanisms may be used to solve issues found in standard BGP implementation.

  4. Improved laser damage threshold performance of calcium fluoride optical surfaces via Accelerated Neutral Atom Beam (ANAB) processing

    Science.gov (United States)

    Kirkpatrick, S.; Walsh, M.; Svrluga, R.; Thomas, M.

    2015-11-01

    Optics are not keeping up with the pace of laser advancements. The laser industry is rapidly increasing its power capabilities and reducing wavelengths which have exposed the optics as a weak link in lifetime failures for these advanced systems. Nanometer sized surface defects (scratches, pits, bumps and residual particles) on the surface of optics are a significant limiting factor to high end performance. Angstrom level smoothing of materials such as calcium fluoride, spinel, magnesium fluoride, zinc sulfide, LBO and others presents a unique challenge for traditional polishing techniques. Exogenesis Corporation, using its new and proprietary Accelerated Neutral Atom Beam (ANAB) technology, is able to remove nano-scale surface damage and particle contamination leaving many material surfaces with roughness typically around one Angstrom. This surface defect mitigation via ANAB processing can be shown to increase performance properties of high intensity optical materials. This paper describes the ANAB technology and summarizes smoothing results for calcium fluoride laser windows. It further correlates laser damage threshold improvements with the smoothing produced by ANAB surface treatment. All ANAB processing was performed at Exogenesis Corporation using an nAccel100TM Accelerated Particle Beam processing tool. All surface measurement data for the paper was produced via AFM analysis on a Park Model XE70 AFM, and all laser damage testing was performed at Spica Technologies, Inc. Exogenesis Corporation's ANAB processing technology is a new and unique surface modification technique that has demonstrated to be highly effective at correcting nano-scale surface defects. ANAB is a non-contact vacuum process comprised of an intense beam of accelerated, electrically neutral gas atoms with average energies of a few tens of electron volts. The ANAB process does not apply mechanical forces associated with traditional polishing techniques. ANAB efficiently removes surface

  5. Nonenzymatic ligation of an RNA oligonucleotide analyzed by atomic force microscopy.

    Science.gov (United States)

    Pino, Samanta; Biasiucci, Mariano; Scardamaglia, Mattia; Gigli, Giuseppe; Betti, Maria Grazia; Mariani, Carlo; Di Mauro, Ernesto

    2011-05-19

    The products of ligation reaction of a 24 nucleotides long PolyA RNA adsorbed on mica were observed by atomic force microscopy. The occurrence of oligonucleotides at different degrees of polymerization has been quantitatively studied before and after ligation reaction. The microscopy images at the nanoscale show that nonenzymatic ligation of pristine RNA monomers results in the formation of supramolecular aggregates, with prevalence of dimers and tetramers. Analytical conditions were defined allowing the identification, the quantitative evaluation, and their distribution after ligation reaction, also providing an estimate of the degree of hydration of the objects. Such investigation is of particular biological relevance and provides the simplest yet model system for direct investigation of RNA reactions by advanced microscopy.

  6. Saponaria officinalis karyology and karyotype by means of image analyzer and atomic force microscopy.

    Science.gov (United States)

    Di Bucchianico, S; Venora, G; Lucretti, S; Limongi, T; Palladino, L; Poma, A

    2008-10-01

    The aim of this work was to offer a contribution to the characterization of taxonomic entity of Saponaria officinalis (2n = 28; an herbaceous perennial species; saporin, a type 1 Ribosome Inactivating Protein, is present in leaves and seeds) by a cytogenetic and karyomorphological approach. We investigated the karyotype's morphometry correlated with Stebbin's symmetric index; the same information has been used for computing the indices resemblance between chromosomes (REC), symmetric indices (SYI), and total form (TF%) which allow the comparison between species and evaluation of karyological evolution. Fluorescence intensities of the stained nuclei were measured by a flow cytometer and, for the first time, values for nuclear DNA content were estimated by comparing nuclei fluorescence intensities of the test population with those of appropriate internal DNA standards. Our study is also aimed to introduce chromosomal volumes, which were determined by atomic force microscopy (AFM), as novel karyomorphological parameter which could allow for chromosome discrimination especially when tiny ones are present.

  7. EXPLORING THE TIME DISPERSION OF THE IBEX-HI ENERGETIC NEUTRAL ATOM SPECTRA AT THE ECLIPTIC POLES

    Energy Technology Data Exchange (ETDEWEB)

    Allegrini, F.; Dayeh, M. A.; Desai, M. I.; Fuselier, S. A.; McComas, D. J. [Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228 (United States); Bzowski, M.; Kubiak, M. A. [Space Research Centre, Polish Academy of Sciences, Bartycka 18A, 00-716 Warsaw (Poland); DeMajistre, R. [Applied Physics Laboratory, Johns Hopkins University, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Funsten, H. O. [Los Alamos National Laboratory, Los Alamos, Bikini Atoll Road, SM 30, NM 87545 (United States); Janzen, P. H.; Reisenfeld, D. B. [Department of Physics and Astronomy, University of Montana, 32 Campus Drive, Missoula, MT (United States); Schwadron, N. [Space Science Center, University of New Hampshire, Morse Hall Room 407, Durham, NH 03824 (United States); Vanderspek, R., E-mail: fallegrini@swri.edu [Massachussetts Institute of Technology, Cambridge, MA 02139 (United States)

    2012-04-20

    The Interstellar Boundary Explorer (IBEX) has observed energetic neutral atom (ENA) hydrogen emissions from the edge of the solar system for more than three years. The observations span energies from 0.01 to 6 keV FWHM. At energies greater than 0.5-6 keV, and for a travel distance of {approx}100 AU, the travel time difference between the slowest and the fastest ENA is more than a year. Therefore, we construct spectra including the effect that slower ENAs left the source at an earlier time than faster ones. If the source produces a steady rate of ENAs and the extinction does not vary, then we expect that the spectral shape would be time independent. However, while the extinction of ENAs has been fairly constant during the first two and a half years, the source appears to have changed, and thus the spectra at a single time may not represent the conditions at the source. IBEX's viewing allows continuous sampling of the ecliptic poles where fluxes can be continuously monitored. For a given source distance we construct spectra assuming that the measured ENAs left the source at roughly the same time. To accomplish this construction, we apply time lag corrections to the signal at different ENA energies that take into account the travel time difference. We show that the spectral shape at the poles exhibits a statistically significant change with time.

  8. Heliosphere for a wide range of interstellar magnetic field strengths as a source of energetic neutral atoms

    CERN Document Server

    Czechowski, A; McComas, D J

    2015-01-01

    Observations of the energetic neutral atoms (ENAs) of heliospheric origin by IBEX differ from expectations based on heliospheric models. It was proposed that the structure of the heliosphere may be similar to the "two-stream" model derived in 1961 by Parker for the case of strong interstellar magnetic field. Using MHD simulations, we examine possible structure of the heliosphere for a wide range of interstellar magnetic field strengths, with different choices of interstellar medium and solar wind parameters. For the model heliospheres, we calculate the fluxes of ENAs created in the inner heliosheath, and compare with IBEX observations. We find that the plasma flow in the model heliospheres for strong interstellar field ($\\sim$20 $\\mu$G) has a "two-stream" structure, which remains visible down to $\\sim$5 $\\mu$G. The obtained ENA flux distribution show the features similar to the "split tail" effect observed by IBEX. In our model, the main cause of this effect is the two component (fast and slow) solar wind str...

  9. PROBING THE NATURE OF THE HELIOSHEATH WITH THE NEUTRAL ATOM SPECTRA MEASURED BY IBEX IN THE VOYAGER 1 DIRECTION

    Energy Technology Data Exchange (ETDEWEB)

    Opher, M.; Prested, C. [Astronomy Department, Boston University, 725 Commonwealth Avenue, Boston, MA (United States); McComas, D. J. [Southwest Research Institute, San Antonio, TX 78238 (United States); Schwadron, N. A. [Department of Physics and Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); Drake, J. F., E-mail: mopher@bu.edu [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742 (United States)

    2013-10-20

    We are able to show by comparing modeled energetic neutral atoms (ENAs) spectra to those measured by Interstellar Boundary Explorer (IBEX) that the models along the Voyager 1 (V1) trajectory that best agree with the low energy IBEX data include extra heating due to ram and magnetic energy in the quasi-stagnation region or a kappa ion distribution (with κ = 2.0) in the outer heliosheath. The model explored is the multi-ion, multi-fluid (MI-MF) which treats the pick-up ions and the thermal ion fluids with separate Maxwellian distributions. These effects are included ad hoc in the modeled ENA since they are not present in the model. These results indicate that the low energy spectra of ENAs as measured by IBEX is sensitive to the physical nature of the heliosheath and to effects not traditionally present in current global models. Therefore, by comparing the low energy ENA spectra to models, we can potentially probe the heliosheath in locations beyond those probed by V1 and Voyager 2 (V2)

  10. Tracking the Solar Cycle through IBEX Observations of Energetic Neutral Atom Flux Variations at the Heliospheric Poles

    Science.gov (United States)

    Reisenfeld, D. B.; Bzowski, M.; Funsten, H. O.; Fuselier, S. A.; Galli, A.; Janzen, P. H.; Karna, N.; Kubiak, M. A.; McComas, D. J.; Schwadron, N. A.; Sokół, J. M.

    2016-12-01

    With seven years of Interstellar Boundary Explorer (IBEX) observations, from 2009 to 2015, we can now trace the time evolution of heliospheric energetic neutral atoms (ENAs) through over half a solar cycle. At the north and south ecliptic poles, the spacecraft attitude allows for continuous coverage of the ENA flux; thus, signal from these regions has much higher statistical accuracy and time resolution than anywhere else in the sky. By comparing the solar wind dynamic pressure measured at 1 au with the heliosheath plasma pressure derived from the observed ENA fluxes, we show that the heliosheath pressure measured at the poles correlates well with the solar cycle. The analysis requires time-shifting the ENA measurements to account for the travel time out and back from the heliosheath, which allows us to estimate the scale size of the heliosphere in the polar directions. We arrive at an estimated distance to the center of the ENA source region in the north of 220 au and in the south a distance of 190 au. We also find a good correlation between the solar cycle and the ENA energy spectra at the poles. In particular, the ENA flux for the highest IBEX energy channel (4.3 keV) is quite closely correlated with the areas of the polar coronal holes, in both the north and south, consistent with the notion that polar ENAs at this energy originate from pickup ions of the very high speed wind (˜700 km s-1) that emanates from polar coronal holes.

  11. Imaging and analyzing the elasticity of vascular smooth muscle cells by atomic force acoustic microscope.

    Science.gov (United States)

    Zhang, Bo; Cheng, Qian; Chen, Ming; Yao, Wengang; Qian, Menglu; Hu, Bing

    2012-08-01

    Vascular smooth muscle cells (VSMCs) play an important role in the good performance of the vasculature. To study the surface, intracellular structure and elasticity of VSMCs, atomic force acoustic microscope (AFAM) was used for imaging VSMCs from A7r5 rat aorta arteries. The topography images of VSMCs were obtained in contact mode and the acoustic images were obtained by AFAM in sample vibration mode. Then, the force curve measurement derived using Young's modulus of the interested areas was used for evaluating elasticity properties. The acoustic images were found in higher resolution with more information than the topography images. The force curves showed the difference in Young's modulus of the different parts of VSMC. These findings demonstrate that AFAM is useful for displaying the surface, structure and elasticity property of VSMCs clearly, with short scanning time, negligible harm or damage to cell and nanometer-level resolution. Copyright © 2012 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  12. Dependency of micro particle adhesion of dispersive and nondispersive interactions analyzed by atomic force microscopy

    CERN Document Server

    Kawal, A; Andoh, E

    1999-01-01

    The adhesion behaviour of a micro semi-sphere tip (radius of curvature of 18 nm) after making contact with various inorganic solid surfaces is analyzed. Measurement force by the AFM tip corresponds to the interactive force estimated $9 using surface energy components, dispersion and nondispersion, based on van der Waal's interaction. These components can be obtained by measuring the contact angle of standard liquids on a material surface. By using two kinds of tip $9 with different component values, analysis of the interactive mechanism and prediction of macro tip (particle) adhesion can be made. (6 refs).

  13. Fragmentation of neutral carbon clusters formed by high velocity atomic collision; Fragmentation d'agregats de carbone neutres formes par collision atomique a haute vitesse

    Energy Technology Data Exchange (ETDEWEB)

    Martinet, G

    2004-05-01

    The aim of this work is to understand the fragmentation of small neutral carbon clusters formed by high velocity atomic collision on atomic gas. In this experiment, the main way of deexcitation of neutral clusters formed by electron capture with ionic species is the fragmentation. To measure the channels of fragmentation, a new detection tool based on shape analysis of current pulse delivered by semiconductor detectors has been developed. For the first time, all branching ratios of neutral carbon clusters are measured in an unambiguous way for clusters size up to 10 atoms. The measurements have been compared to a statistical model in microcanonical ensemble (Microcanonical Metropolis Monte Carlo). In this model, various structural properties of carbon clusters are required. These data have been calculated with Density Functional Theory (DFT-B3LYP) to find the geometries of the clusters and then with Coupled Clusters (CCSD(T)) formalism to obtain dissociation energies and other quantities needed to compute fragmentation calculations. The experimental branching ratios have been compared to the fragmentation model which has allowed to find an energy distribution deposited in the collision. Finally, specific cluster effect has been found namely a large population of excited states. This behaviour is completely different of the atomic carbon case for which the electron capture in the ground states predominates. (author)

  14. Ion-neutral chemistry at ultralow energies: Dynamics of reactive collisions between laser-cooled Ca^+ ions and Rb atoms in an ion-atom hybrid trap

    CERN Document Server

    Hall, Felix H J; Hegi, Gregor; Raoult, Maurice; Aymar, Mireille; Dulieu, Olivier; Willitsch, Stefan

    2013-01-01

    Cold chemical reactions between laser-cooled Ca^+ ions and Rb atoms were studied in an ion-atom hybrid trap. Reaction rate constants were determined in the range of collision energies /k_B = 20 mK-20 K. The lowest energies were achieved in experiments using single localized Ca^+ ions. Product branching ratios were studied using resonant-excitation mass spectrometry. The dynamics of the reactive processes in this system (non-radiative and radiative charge transfer as well as radiative association leading to the formation of CaRb^+ molecular ions) have been analyzed using high-level quantum-chemical calculations of the potential energy curves of CaRb^+ and quantum-scattering calculations for the radiative channels. For the present low-energy scattering experiments, it is shown that the energy dependence of the reaction rate constants is governed by long-range interactions in line with the classical Langevin model, but their magnitude is determined by short-range non-adiabatic and radiative couplings which only ...

  15. Mass-analyzed threshold ionization (MATI) spectroscopy of atoms and molecules using VUV synchrotron radiation.

    Science.gov (United States)

    Kostko, Oleg; Kim, Sang Kyu; Leone, Stephen R; Ahmed, Musahid

    2009-12-31

    Mass-analyzed threshold ionization (MATI) spectroscopy using synchrotron radiation (Advanced Light Source, Lawrence Berkeley National Laboratory) has been performed for Ar, N(2), O(2), N(2)O, H(2)O, C(2)H(2), and C(6)H(6). MATI allows for a better determination of ionization energies compared to those derived from photoionization efficiency curves traditionally used in synchrotron photoionization mass spectrometry. The separation of the long-lived Rydberg state from the directly formed prompt ion, essential for a meaningful MATI spectrum, has been accomplished by employing an arrangement of ion optics coupled to unique electric field pulsing schemes. For Ar, a number of resolved bands below the ionization energy are observed, and these are ascribed to high-n,l Rydberg states prepared in the MATI scheme. The first vibrational state resolved MATI spectra of N(2) and O(2) are reported, and spectral characteristics are discussed in comparison with previously reported threshold photoelectron spectroscopic studies. Although MATI performed with synchrotron radiation is intrinsically less sensitive compared to laser-based sources, this work demonstrates that MATI spectroscopy performed with widely tunable vacuum ultraviolet (VUV) radiation is a complementary technique for studying the ionization spectroscopy of polyatomic molecules.

  16. Spatial dependence of polycrystalline FTO’s conductance analyzed by conductive atomic force microscope (C-AFM)

    Energy Technology Data Exchange (ETDEWEB)

    Peixoto, Alexandre Pessoa; Costa, J. C. da [Department of Electrical Engineering, University of Brasília, Campus Universitário Darcy Ribeiro, Asa Norte, PO Box 4386, Brasília - DF, 70919-970 (Brazil)

    2014-05-15

    Fluorine-doped Tin oxide (FTO) is a highly transparent, electrically conductive polycrystalline material frequently used as an electrode in organic solar cells and optical-electronic devices [1–2]. In this work a spatial analysis of the conductive behavior of FTO was carried out by Conductive-mode Atomic Force Microscopy (C-AFM). Rare highly oriented grains sample give us an opportunity to analyze the top portion of polycrystalline FTO and compare with the border one. It is shown that the current flow essentially takes place through the polycrystalline edge at grain boundaries.

  17. Performance evaluation of different diamond-like carbon samples as charge state conversion surfaces for neutral atom imaging detectors in space applications

    Science.gov (United States)

    Brigitte Neuland, Maike; Allenbach, Marc; Föhn, Martina; Wurz, Peter

    2017-04-01

    The detection of energetic neutral atoms is a substantial requirement on every space mission mapping particle populations of a planetary magnetosphere or plasma of the interstellar medium. For imaging neutrals, these first have to be ionised. Regarding the constraints of weight, volume and power consumption, the technique of surface ionisation complies with all specifications of a space mission. Particularly low energy neutral atoms, which cannot be ionised by passing through a foil, are ionised by scattering on a charge state conversion surface [1]. Since more than 30 years intense research work is done to find and optimise suitable materials for use as charge state conversion surfaces for space application. Crucial parameters are the ionisation efficiency of the surface material and the scattering properties. Regarding these parameters, diamond-like carbon was proven advantageously: While efficiently ionising incoming neutral atoms, diamond stands out by its durability and chemical inertness [2]. In the IBEX-Lo sensor, a diamond-like carbon surface is used for ionisation of neutral atoms. Building on the successes of the IBEX mission [3], the follow up mission IMAP (InterstellarMApping Probe) will take up to further explore the boundaries of the heliosphere. The IMAP mission is planned to map neutral atoms in a larger energy range and with a distinct better angular resolution and sensitivity than IBEX [4]. The aspired performance of the IMAP sensors implies also for charge state conversion surfaces with improved characteristics. We investigated samples of diamond-like carbon, manufactured by the chemical vapour deposition (CVD) method, regarding their ionisation efficiency, scattering and reflexion properties. Experiments were carried out at the ILENA facility at the University of Bern [5] with hydrogen and oxygen atoms, which are the species of main interest in magnetospheric research [1]. We compare the results of earlier investigations of a metallised CVD

  18. Atomic Parity Violation, Muon Pair Production in e+e - Collisions and Detection of CDM WIMP-Physics Related to Neutral Vector Boson D1

    Science.gov (United States)

    Senju, H.

    1999-11-01

    In our preon model there exists a neutral vector boson D1 which is an isoscalar partner of W(Z) in the vector boson octet. It is shown that the exchange of a D1 of about 1 TeV mass naturally explains a positive excess of the weak charge of atomic cesium recently observed. Other processes occurring through the D1 exchange are discussed, including the detection of CDM WIMP.

  19. Transient Enhancement ('Spike-on-Tail') Observed on Neutral-Beam-Injected Energetic Ion Spectra Using the E||B Neutral Particle Analyzer in the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Medley, S. S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Gorelenkov, N. N. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Bell, R. E. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Fredrickson, E. D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Gerhardt, S. P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); LeBlanc, B. P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Podesta, M. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Roquemore, A. L. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

    2010-06-01

    An increase of up to four-fold in the E||B Neutral Particle Analyzer (NPA) charge exchange neutral flux localized at the Neutral Beam (NB) injection full energy is observed in the National Spherical Torus Experiment (NSTX). Termed the High-Energy Feature (HEF), it appears on the NB-injected energetic ion spectrum only in discharges where tearing or kink-type modes (f < 10 kHz) are absent, TAE activity (f ~ 10-150 kHz) is weak (δBrms < 75 mGauss) and CAE/GAE activity (f ~ 400 – 1200 kHz) is robust. The feature exhibits a growth time of ~ 20 - 80 ms and occasionally develops a slowing down distribution that continues to evolve over periods of 100's of milliseconds, a time scale long compared with the typical ~ 10's ms equilibration time of the NB injected particles. The HEF is observed only in H-mode (not L-mode) discharges with injected NB power of 4 MW or greater and in the field pitch range v||/v ~ 0.7 – 0.9; i.e. only for passing (never trapped) energetic ions. The HEF is suppressed by vessel conditioning using lithium deposition at rates ~ 100 mg/shot, a level sufficient to suppress ELM activity. Increases of ~ 10 - 30 % in the measured neutron yield and total stored energy are observed to coincide with the feature along with broadening of measured Te(r), Ti(r) and ne(r) profiles. However, TRANSP analysis shows that such increases are driven by plasma profile changes and not the HEF phenomenon itself. Though a definitive mechanism has yet to be developed, the HEF appears to be caused by a form of TAE/CAE wave-particle interaction that distorts of the NB fast ion distribution in phase space.

  20. Atoms

    Institute of Scientific and Technical Information of China (English)

    刘洪毓

    2007-01-01

    Atoms(原子)are all around us.They are something like the bricks (砖块)of which everything is made. The size of an atom is very,very small.In just one grain of salt are held millions of atoms. Atoms are very important.The way one object acts depends on what

  1. Observation of single neutral atoms in a large-magnetic-gradient vapour-cell magneto-optical trap

    Institute of Scientific and Technical Information of China (English)

    Wang Jing; He Jun; Qiu Ying; Yang Bao-Dong; Zhao Jiang-Yan; Zhang Tian-Cai; Wang Jun-Min

    2008-01-01

    Single caesium atoms in a large-magnetic-gradient vapour-cell magneto-optical trap have been identified. The trapping of individual atoms is marked by the steps in fluorescence signal corresponding to the capture or loss of single atoms. The typical magnetic gradient is about 29 mT/cm, which evidently reduces the capture rate of magneto-optical trap.

  2. Evaluation of lithium determination in three analyzers: flame emission, flame atomic absorption spectroscopy and ion selective electrode

    Directory of Open Access Journals (Sweden)

    Mehri Aliasgharpour

    2009-10-01

    Full Text Available Background: Lithium carbonate salt has become an increasingly important substance in the treatment of manic depressive disorders, and its relatively narrow therapeutic range has caused laboratories to monitor the serum concentration carefully. In the present work we evaluated lithium measurement in 3 different analyzers. Methods & Materials: Three different analyzers including Flame Emission (FES, Flame Atomic Absorption Spectroscopy (FAAS, and Ion Selective Electrode (ISE were used. All chemicals had a grade suitable for trace metal analysis. Results: Within-day precision of CV was ≤ 1.5% for FES & FAAS, except for ISE (1.9% CV. Between-days precision of CV was less for FES than for FAAS and ISE (1.3% versus 2.2% & 2.3%. The percent recovery of added lithium in pooled patients’ serum was higher for ISE than for FASS and FES (103.4% versus 96.2% and 94.6%. We also obtained a higher average lithium concentration for patients’ serum samples (n=16 measured by ISE than for FAAS and FES (0.825±0.30 versus 0.704±0.26 & 0.735±0.19. Paired t-test results revealed a significant difference (p< 0.001 for patient sera analyzed with FAAS and ISE. Conclusion: We report higher results for ISE than the other two analyzers and conclude that the choice between the two flame methods for patients’ serum lithium determination is arbitrary and that FES analyzer is a more attractive routine alternative for lithium determination than FAAS because of its cost and ease of performance. In addition, the results obtained by ISE are precise. However, its accuracy may depend on other interfering factors.

  3. Neutral Particle Analyzer Vertically Scanning Measurements of MHD-induced Energetic Ion Redistribution or Loss in the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    S.S. Medley, R. Andre, R.E. Bell, D.S. Darrow, C.W. Domier, E.D. Fredrickson, N.N. Gorelenkov, S.M. Kaye, B.P. LeBlanc, K.C. Lee, F.M. Levinton, D. Liu, N.C. Luhmann, Jr., J.E. Menard, H. Park, D. Stutman, A.L. Roquemore, K. Tritz, H. Yuh and the NSTX Team

    2007-11-15

    Observations of magneto-hydro-dynamic (MHD) induced redistribution or loss of energetic ions measured using the vertically scanning capability of the Neutral Particle Analyzer diagnostic on the National Spherical Torus Experiment (NSTX) are presented along with TRANSP and ORBIT code analysis of the results. Although redistribution or loss of energetic ions due to bursting fishbone-like and low-frequency (f ~ 10 kHz) kinktype MHD activity has been reported previously, the primary goal of this work is to study redistribution or loss due to continuous Alfvénic (f ~ 20 – 150 kHz) modes, a topic that heretofore has not been investigated in detail for NSTX plasmas. Initial indications are that the former drive energetic ion loss whereas the continuous Alfvénic modes only cause redistribution and the energetic ions remain confined.

  4. Ground test equipment for neutral atom imaging system-high%中性原子成像仪地检电子系统的研制

    Institute of Scientific and Technical Information of China (English)

    明晨曦; 余庆龙; 梁金宝; 张焕新; 荆涛

    2016-01-01

    This paper introduces the structure and working principle of the Neutral Atom Imaging System-High (NAIS-H) which is in the MIT project. Based on the testing needs of the instrument, we have designed ground test equipment, including the circuit system and the host computer system. In this paper, we show the structure and working principle of the ground test for NAIS-H, and tell structure and java programming of the sub modules of the host computer system in detail, such as API communicating system, data analyzing system and data saving system. At last, we test the equipment, and the result shows the ground test system has good performance and achieves the design requirement.%本文介绍了MIT卫星计划中性原子成像仪(NAIS-H)的基本结构以及工作原理,通过分析MIT卫星NAIS-H的工作原理及测试需求,设计并实现了基于该成像仪的地面检测,包括硬件电路系统及上位机软件系统.本文分别从通讯、数据处理等方面,描述了地检系统的主要结构设计以及工作流程,并详述了上位机系统中串口通讯、数据解包、图像处理等各软件模块设计以及java代码编写.最后,对地检系统进行测试,得到的结果显示该系统具有良好的性能,达到了设计要求.

  5. The influence of plasma horizontal position on the neutron rate and flux of neutral atoms in injection heating experiment on the TUMAN-3M tokamak

    Science.gov (United States)

    Kornev, V. A.; Chernyshev, F. V.; Melnik, A. D.; Askinazi, L. G.; Wagner, F.; Vildjunas, M. I.; Zhubr, N. A.; Krikunov, S. V.; Lebedev, S. V.; Razumenko, D. V.; Tukachinsky, A. S.

    2013-11-01

    Horizontal displacement of plasma along the major radius has been found to significantly influence the fluxes of 2.45 MeV DD neutrons and high-energy charge-exchange atoms from neutral beam injection (NBI) heated plasma of the TUMAN-3M tokamak. An inward shift by Δ R = 1 cm causes 1.2-fold increase in the neutron flux and 1.9-fold increase in the charge-exchange atom flux. The observed increase in the neutron flux is attributed to joint action of several factors-in particular, improved high-energy ion capture and confinement and, probably, decreased impurity inflow from the walls, which leads to an increase in the density of target ions. A considerable increase in the flux of charge-exchange neutrals in inward-shifted plasma is due to the increased number of captured high-energy ions and, to some extent, the increased density of the neutral target. As a result of the increase in the content of high-energy ions, the central ion temperature T i (0) increased from 250 to 350 eV. The dependence of the neutron rate on major radius R 0 should be taken into account when designing compact tokamak-based neutron sources.

  6. Atomic force microscopy for analyzing metaphase chromosomes: comparison of AFM images with fluorescence labeling images of banding patterns.

    Science.gov (United States)

    Hoshi, Osamu; Ushiki, Tatsuo

    2014-01-01

    The combined use of fluorescence microscopy with atomic force microscopy (AFM) has been introduced to analyze the replication-banding patterns of human chromosomes. Human lymphocytes synchronized with excess thymidine are treated with 5-ethynyl-2'-deoxyuridine (EdU) during the late S phase. EdU-labeled DNA is detected in metaphase chromosomes using Alexa Fluor 488(®) azide, through the 1,3-dipolar cycloaddition reaction of organic azides with the terminal acetylene group of EdU. Chromosomes with EdU incorporated during the late S phase show a banding pattern similar to the G-banding pattern of normal human chromosomes. The comparison between the fluorescence and AFM image of the same chromosome indicates the presence of ridges and grooves in the chromatid arms, which correspond to G-positive and G-negative bands, respectively. This technique of EdU-labeled replication bands combined with AFM is useful to analyze the structure of chromosomes in relation to the banding pattern.

  7. Atomic Diffusion in Cu/Si (111) and Cu/SiO2/Si (111) Systems by Neutral Cluster Beam Deposition

    Institute of Scientific and Technical Information of China (English)

    CAO Bo; LI Gong-Ping; CHEN Xi-Meng; CHO Seong-Jin; KIM Hee

    2008-01-01

    @@ The Cu films are deposited on two kinds of p-type Si (111) substrates by ionized cluster beam (ICB) technique.The interface reaction and atomic diffusion of Cu/Si (111) and Cu/SiO2/Si (111) systems are studied at different annealing temperatures by x-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Some significant results are obtained: For the Cu/Si (111) samples prepared by neutral clusters, the interdiffusion of Cu and Si atoms occurs when annealed at 230℃. The diffusion coefficients of the samples annealed at 230℃and 500℃ are 8.5 × 10-15 cm2.s-1 and 3.0 × 10-14 cm2.s-1, respectively. The formation of the copper-silicide phase is observed by XRD, and its intensity becomes stronger with the increase of annealing temperature. For the Cu/SiO2/Si (111) samples prepared by neutral clusters, the interdiffusion of Cu and Si atoms occurs and copper silicides are formed when annealed at 450℃. The diffusion coefficients of Cu in Si are calculated to be 6.0 × 10-16 cm2.s-1 at 450℃, due to the fact that the existence of the SiO2 layer suppresses the interdiffusion of Cu and Si.

  8. The DEPOSIT computer code: Calculations of electron-loss cross-sections for complex ions colliding with neutral atoms

    Science.gov (United States)

    Litsarev, Mikhail S.

    2013-02-01

    A description of the DEPOSIT computer code is presented. The code is intended to calculate total and m-fold electron-loss cross-sections (m is the number of ionized electrons) and the energy T(b) deposited to the projectile (positive or negative ion) during a collision with a neutral atom at low and intermediate collision energies as a function of the impact parameter b. The deposited energy is calculated as a 3D integral over the projectile coordinate space in the classical energy-deposition model. Examples of the calculated deposited energies, ionization probabilities and electron-loss cross-sections are given as well as the description of the input and output data. Program summaryProgram title: DEPOSIT Catalogue identifier: AENP_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENP_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License version 3 No. of lines in distributed program, including test data, etc.: 8726 No. of bytes in distributed program, including test data, etc.: 126650 Distribution format: tar.gz Programming language: C++. Computer: Any computer that can run C++ compiler. Operating system: Any operating system that can run C++. Has the code been vectorised or parallelized?: An MPI version is included in the distribution. Classification: 2.4, 2.6, 4.10, 4.11. Nature of problem: For a given impact parameter b to calculate the deposited energy T(b) as a 3D integral over a coordinate space, and ionization probabilities Pm(b). For a given energy to calculate the total and m-fold electron-loss cross-sections using T(b) values. Solution method: Direct calculation of the 3D integral T(b). The one-dimensional quadrature formula of the highest accuracy based upon the nodes of the Yacobi polynomials for the cosθ=x∈[-1,1] angular variable is applied. The Simpson rule for the φ∈[0,2π] angular variable is used. The Newton-Cotes pattern of the seventh order

  9. [Using atomic force microscopy to analyze morphological changes and mechanical properties caused by cellular exposure to low doses of pesticides].

    Science.gov (United States)

    L'Abbate, N; Lasalvia, M; Perna, G; D'Antonio, P; Quartucci, G; Gallo, C; Capozzi, V

    2012-01-01

    A commercial pesticide is usually composed of active ingredients and formulants. Among the active ingredients, Deltamethrin is a pyrethroid chemical widely used for synthesizing pesticides products which are very effective in damaging the central nervous system of pests. In this work, we analyze, by means of atomic force microscopy (AFM), cellular morphological changes induced by exposure to a Deltamethrin-based commercial pesticide (Decaflow). AFM microscopy, in addition to the well-known characterization of the cellular topography, has the ability to monitor interesting biomechanical parameters of the surface as roughness and elastic modulus. In particular, we exposed normal human keratinocytes for 24 hours at different solutions of Decaflow, well below the threshold of cytotoxicity. The AFM images of exposed cells show alterations of surface cell shape. Moreover exposed cells are characterized by an increase of the value of membrane roughness. The mechanical properties of cells are also modified after Decaflow exposure, as confirmed by a decrease of the elasticity modulus with increasing the concentration of pesticide.

  10. Analyzing the equilibrium states of a quasi-neutral spatially inhomogeneous system of charges above a liquid dielectric film based on the first principles of quantum statistics

    Science.gov (United States)

    Lytvynenko, D. M.; Slyusarenko, Yu V.

    2017-08-01

    A theory of quasi-neutral equilibrium states of charges above a liquid dielectric surface is developed. This theory is based on the first principles of quantum statistics for systems comprising many identical particles. The proposed approach involves applying the variational principle, modified for the considered systems, and the Thomas-Fermi model. In the terms of the developed theory self-consistency equations are obtained. These equations provide the relation between the main parameters describing the system: the potential of the static electric field, the distribution function of charges and the surface profile of the liquid dielectric. The equations are used to study the phase transition in the system to a spatially periodic state. The proposed method can be applied in analyzing the properties of the phase transition in the system in relation to the spatially periodic states of wave type. Using the analytical and numerical methods, we perform a detailed study of the dependence of the critical parameters of such a phase transition on the thickness of the liquid dielectric film. Some stability criteria for the new asymmetric phase of the studied system are discussed.

  11. Measuring Atomic and Molecular Species in the Upper Atmosphere up to 1000 km with the Free-Fall Mass Spectrometer and the Small Deflection Energy Analyzer

    Science.gov (United States)

    Herrero, F.; Nicholas, A.

    2007-05-01

    Atomic oxygen (O), the major constituent of the Earth's thermosphere above 200 km altitude is both a driver and a tracer of atmospheric motions in the thermosphere and plays a pivotal role in interactions with the ionosphere through ion-drag and chemical reactions. At altitudes above 400 to 500 km, the energies and composition may reveal interactions with the magnetosphere. In addition, satellites in low-Earth orbit require knowledge of O densities to address engineering issues in low-Earth-orbit missions. The major difficulties in O measurements involve ambiguities due to the recombination of O in the sensor surfaces to yield O2 which is then measured with a mass spectrometer; similar difficulties exist for atomic hydrogen H and nitrogen N. In this paper we describe the use of our new charged particle spectrometers to measure relative densities and energies of the neutral and ion constituents in the upper atmosphere and into the exosphere to about 1000 km altitude. Neutral atoms are ionized before striking internal surfaces and surface-accommodated atoms and molecules are discriminated from incident ones according to their energies. Our ion source sensitivity is about 1.3x10-4/s per microAmp electron beam current for a number density of 1/cm3. Thus, operating with 1 mA emission (about 0.2W cathode power), signals of 100/s with integration period of 1 second correspond to a neutral atom density of about 103/cm3 with 10% variance. At very high altitudes, the lowest densities occur with the coldest thermopause - a 750K thermopause having an O density of about 150/cm3 at 1000 km, much higher densities for H and He, and much lower for O2 and N2. Total power for the spectrometer suite is less than 0.5 W with a mass of about 0.5 kg, based on our current versions. We plan to propose development of the sensor suite for two missions; one at 400 km and one at 830 km.

  12. Influence of energetic ions and neutral atoms on the L1 0 ordering of FePt films

    Science.gov (United States)

    Cantelli, V.; von Borany, J.; Mücklich, A.; Zhou, Shengqiang; Grenzer, J.

    2007-04-01

    The A1 → L10 phase transition of Fe50Pt50 films, deposited at room-temperature on amorphous SiO2 by dc magnetron co-sputtering at 0.3 Pa, was studied with in-situ X-ray diffraction. An almost complete transition characterized by a long-range order parameter S > 0.8 is obtained already after a heat treatment at (320 ± 20) °C. A post-deposition He ion irradiation (50 keV, 1 × 1015 - 3 × 1016 cm-2) does not further reduce the transition temperature. Theoretical calculations reveal that, due to the negligible thermalization of the sputtered atoms and reflected ions in the plasma, a considerable fraction of energetic ions and atoms meet the substrate surface. The low transition temperature is explained by the impact of energetic ions and atoms which provoke significant adatom mobility and a decrease of the activation energy for atomic reordering by vacancies. Consequently, using deposition parameters leading to a strong thermalized plasma, the FePt films showed an increase of the transition temperature up to 400 °C, a lower S-value (S ≅ 0.6) and a reduced coercivity.

  13. Peripheral leukocyte anomaly detected with routine automated hematology analyzer sensitive to adipose triglyceride lipase deficiency manifesting neutral lipid storage disease with myopathy/triglyceride deposit cardiomyovasculopathy

    National Research Council Canada - National Science Library

    Suzuki, Akira; Nagasaka, Hironori; Ochi, Yasuhiro; Kobayashi, Kazuhiro; Nakamura, Hiroshi; Nakatani, Daisaku; Yamaguchi, Satoshi; Yamaki, Shinobu; Wada, Atsushi; Shirata, Yoshihisa; Hui, Shu-Ping; Toda, Tatsushi; Kuroda, Hiroshi; Chiba, Hitoshi; Hirano, Ken-ichi

    2014-01-01

    Adipose triglyceride lipase (ATGL) deficiency manifesting neutral lipid storage disease with myopathy/triglyceride deposit cardiomyovasculopathy presents distinct fat-containing vacuoles known as Jordans' anomaly in peripheral leucocytes...

  14. Evaluation of effervescent atomizer internal design on the spray unsteadiness using a phase/Doppler particle analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Meng; Duan, YuFeng; Zhang, TieNan [School of Energy and Environment, Southeast University, Sipailou 2, Nanjing 210096 (China)

    2010-09-15

    The purpose of this research was to investigate the dependence of effervescent spray unsteadiness on operational conditions and atomizer internal design by the ideal spray theory of Edwards and Marx. The convergent-divergent effervescent atomizer spraying water with air as atomizing medium in the ''outside-in'' gas injection was used in this study. Results demonstrated that droplet formation process at various air to liquid ratio (ALR) led to the spray unsteadiness and all droplet size classes exhibited unsteadiness behavior in spray. The spray unsteadiness reduced quickly at ALR of 3% and decreased moderately at ALR of other values as the axial distance increased. When the axial distance was 200 mm, the spray unsteadiness reduced dramatically with the increase in radial distance, but lower spray unsteadiness at the center of spray and higher spray unsteadiness at the edge of spray were shown as the axial distance increased. The spray unsteadiness at the center region of spray increased with the injection pressure. Low spray unsteadiness and good atomization performance can be obtained when the diameter of incline aeration holes increased at ALR of 10%. Although short mixing chamber with large discharge orifice diameter for convergent-divergent effervescent atomizer produced good atomization, the center region of spay showed high spray unsteadiness and maybe formed the droplet clustering. (author)

  15. Probing the dynamic structure factor of a neutral Fermi superfluid along the BCS-BEC crossover using atomic impurity qubits

    Science.gov (United States)

    Mitchison, Mark T.; Johnson, Tomi H.; Jaksch, Dieter

    2016-12-01

    We study an impurity atom trapped by an anharmonic potential, immersed within a cold atomic Fermi gas with attractive interactions that realizes the crossover from a Bardeen-Cooper-Schrieffer superfluid to a Bose-Einstein condensate. Considering the qubit comprising the lowest two vibrational energy eigenstates of the impurity, we demonstrate that its dynamics probes the equilibrium density fluctuations encoded in the dynamic structure factor of the superfluid. Observing the impurity's evolution is thus shown to facilitate nondestructive measurements of the superfluid order parameter and the contact between collective and single-particle excitation spectra. Our setup constitutes a model of an open quantum system interacting with a thermal reservoir, the latter supporting both bosonic and fermionic excitations that are also coupled to each other.

  16. Optimization of the loading rate of magneto-optical trap for neutral mercury atom%中性汞原子磁光阱装载率的优化∗

    Institute of Scientific and Technical Information of China (English)

    苟维; 刘亢亢; 付小虎; 赵儒臣; 孙剑芳; 徐震

    2016-01-01

    Optics lattice clock is a hot topic in the researches of frequency standard and metrology. Neutral mercury atom is one of the most promising candidates for optical lattice clock. Due to its large atomic number, mercury atom is insensitive to black body radiation, which is the severe limitation for developing the optical lattice clocks. To realize the optical lattice clock of neutral mercury atoms, the first step is to implement laser-cooling and trapping of neutral mercury atoms. The cooling transition of mercury atom is 1S0–3P1 transition. The wavelength is 253.7 nm, the line width is 1.27 MHz, and the saturation intensity is 10.2 mW/cm2. Quantum projection noise (QPN) is an important parameter that affects optical lattice clock. Increasing the loading rate of magneto-optical trap (MOT) can help lower the QPN, thereby improving the performance of optical lattice clock. In this work, we calculate the scattering force of deep UV cooling laser, which is exerted on mercury atom in our single chamber MOT, and numerically simulate the one-dimensional motion of the atom in the MOT. It gives us the capture velocity under optimized parameters of the MOT. Then we calculate the loading rate of three-dimensional MOT by a high efficient random sampling method. According to the rate equation of MOT, the loading rate is proportional to the atom number of the steady state, which is the accessible parameter in the experiment. An experimental setup of MOT is established with a high vacuum system and a frequency quadrupled semiconductor laser system. The fluorescence imaging on an EMCCD gives the atom number in the MOT. We also calibrate the vapor density of background mercury gas in the vacuum, and measure the atom number in a steady MOT. We numerically simulate and experimentally study the influences on the atom number on the parameters of MOT, such as laser intensity, laser detuning and magnetic field gradient. The calculated results are in consistent with the experimental

  17. Neutral atomic-carbon QSO absorption-line systems at z>1.5: Sample selection, HI content, reddening, and 2175 A extinction feature

    CERN Document Server

    Ledoux, C; Petitjean, P; Srianand, R

    2015-01-01

    We present the results of a search for cold gas at high redshift along QSO lines-of-sight carried out without any a priori assumption on the neutral atomic-hydrogen (HI) content of the absorbers. To do this, we systematically looked for neutral-carbon (CI) 1560,1656 transition lines in low-resolution QSO spectra from the SDSS database. We built up a sample of 66 CI absorbers with redshifts 1.521 compared to systematic DLA surveys. We study empirical relations between W_r(CI), N(HI), E(B-V) and the strength of the 2175 A extinction feature, the latter being detected in about 30% of the CI absorbers. We show that the 2175 A feature is weak compared to Galactic lines-of-sight exhibiting the same amount of reddening. This is probably the consequence of current or past star formation in the vicinity of the CI systems. We also find that the strongest CI systems tend to have the largest amounts of dust and that the metallicity of the gas and its molecular fraction is likely to be high in a large number of cases.

  18. The Star Formation Rate Efficiency of Neutral Atomic-dominated Hydrogen Gas in the Outskirts of Star Forming Galaxies from z~1 to z~3

    CERN Document Server

    Rafelski, Marc; Fumagalli, Michele; Neeleman, Marcel; Teplitz, Harry I; Grogin, Norman; Koekemoer, Anton M; Scarlata, Claudia

    2016-01-01

    Current observational evidence suggests that the star formation rate (SFR) efficiency of neutral atomic hydrogen gas measured in Damped Ly-alpha Systems (DLAs) at z~3 is more than 10 times lower than predicted by the Kennicutt-Schmidt (KS) relation. To understand the origin of this deficit, and to investigate possible evolution with redshift and galaxy properties, we measure the SFR efficiency of atomic gas at z~1, z~2, and z~3 around star-forming galaxies. We use new robust photometric redshifts in the Hubble Ultra Deep Field to create galaxy stacks in these three redshift bins, and measure the SFR efficiency by combining DLA absorber statistics with the observed rest-frame UV emission in the galaxies' outskirts. We find that the SFR efficiency of HI gas at z>1 is ~1-3% of that predicted by the KS relation. Contrary to simulations and models that predict a reduced SFR efficiency with decreasing metallicity and thus with increasing redshift, we find no significant evolution in the SFR efficiency with redshift...

  19. Feasibility of detecting single atoms using photonic bandgap cavities

    OpenAIRE

    Lev, Benjamin; Srinivasan, Kartik; Barclay, Paul; Painter, Oskar; Mabuchi, Hideo

    2004-01-01

    We propose an atom-cavity chip that combines laser cooling and trapping of neutral atoms with magnetic microtraps and waveguides to deliver a cold atom to the mode of a fiber taper coupled photonic bandgap (PBG) cavity. The feasibility of this device for detecting single atoms is analyzed using both a semi-classical treatment and an unconditional master equation approach. Single-atom detection seems achievable in an initial experiment involving the non-deterministic delivery of weakly trapped...

  20. The response of a neutral atom to a strong laser field probed by transient absorption near the ionisation threshold

    CERN Document Server

    Simpson, E R; Austin, D R; Diveki, Z; Hutchinson, S E E; Siegel, T; Ruberti, M; Averbukh, V; Miseikis, L; Strüber, C; Chipperfield, L; Marangos, J P

    2015-01-01

    We present transient absorption spectra of an extreme ultraviolet attosecond pulse train in helium dressed by an 800 nm laser field with intensity ranging from $2\\times10^{12}$ W/cm$^2$ to $2\\times10^{14}$ W/cm$^2$. The energy range probed spans 16-42 eV, straddling the first ionisation energy of helium (24.59 eV). By changing the relative polarisation of the dressing field with respect to the attosecond pulse train polarisation we observe a large change in the modulation of the absorption reflecting the vectorial response to the dressing field. With parallel polarized dressing and probing fields, we observe significant modulations with periods of one half and one quarter of the dressing field period. With perpendicularly polarized dressing and probing fields, the modulations of the harmonics above the ionisation threshold are significantly suppressed. A full-dimensionality solution of the single-atom time-dependent Schr\\"odinger equation obtained using the recently developed ab-initio time-dependent B-spline...

  1. Comments on alternative calculations of the broadening of spectral lines of neutral sodium by H-atom collisions

    CERN Document Server

    Barklem, P S

    2001-01-01

    With the exception of the sodium D-lines recent calculations of line broadening cross-sections for several multiplets of sodium by Leininger et al (2000) are in substantial disagreement with cross-sections interpolated from the tables of Anstee and O'Mara (1995) and Barklem and O'Mara (1997). The discrepancy is as large as a factor of three for the 3p-4d multiplet. The two theories are tested by using the results of each to synthesize lines in the solar spectrum. It is found that generally the data from the theory of Anstee, Barklem and O'Mara produce the best match to the observed solar spectrum. It is found, using a simple model for reflection of the optical electron by the potential barrier between the two atoms, that the reflection coefficient is too large for avoided crossings with the upper states of subordinate lines to contribute to line broadening, supporting the neglect of avoided ionic crossings by Anstee, Barklem and O'Mara for these lines. The large discrepancies between the two sets of calculati...

  2. Analyzing and studying factors for determining neutral point position of fully grouted rock bolt%全长注浆岩石锚杆中性点影响因素分析研究

    Institute of Scientific and Technical Information of China (English)

    朱训国; 杨庆

    2009-01-01

    The neutral point theory is the important theory in underground engineering reinforcement theory. At present, the formula to determine neutral point position has been existed some unreasonable place. The neutral point theory had been further consummated and improved on the foundation of pre-researchers. Base on the developed analytical model and the theory of frictional resistance is zero at the neutral point, the factors have been detailed analyzed for affecting the neutral point position; and the correlations have been gained which affecting neutral point position. Through analyzing, it is revealed that the hydrostatic primary stress, bolt length, bolt spacing having no influence to neutral point position, and the radius of tunnel, Young's moduli of rock and bolt, the bolt diameter having remarkable influence to it. Among them, it is linear relation among the radius of tunnel, the bolt diameter with the neutral point position, but it is exponential function relations among the Young's modulus of rock and bolt with the neutral point position. The relationship of Young's modulus of rock mass and neutral point position presents exponential decreasing; the relationship of -Young's modulus of bolt and neutral point position presents exponential increasing. Through the factors analyzed, it has obtained that the general functional between the neutral point position and the correlation parameter, for further to study the neutral point theory providing the certain reference significance.%中性点理论是地下工程锚固理论中的重要理论,但目前对于中性点位置的确定计算公式存在不合理之处.在前人工作的基础上,对中性点理论进行了完善和改进.在建立的锚杆解析本构模型的基础上,结合中性点理论中锚杆中性点位置处的摩阻力为0的思想,对影响中性点位置的因素进行了较详细的分析,得出了影响锚杆中性点位置的相关因素.通过分析研究得到,

  3. Analysis of the Aberration in Directly-writing Atom Lithography

    Institute of Scientific and Technical Information of China (English)

    LI Chuanwen; CAI Weiquan; WANG Yuzhu

    2000-01-01

    After deriving the approximation solution which describes the motion of neutral atoms in an optical standing wave field with large detuning, the spherical aberration and the chromatic aberration are analyzed and possible methods to reduce these aberrations are discussed.

  4. Imprint of the Sun’s Evolving Polar Winds on IBEX Energetic Neutral Atom All-sky Observations of the Heliosphere

    Science.gov (United States)

    Zirnstein, E. J.; Dayeh, M. A.; McComas, D. J.; Sokół, J. M.

    2017-09-01

    With 7 years of Interstellar Boundary Explorer (IBEX) measurements of energetic neutral atoms (ENAs), IBEX has shown a clear correlation between dynamic changes in the solar wind and the heliosphere’s response in the formation of ENAs. In this paper, we investigate temporal variations in the latitudinal-dependent ENA spectrum from IBEX and their relationship to the solar wind speed observed at 1 au. We find that the variation in latitude of the transition in ENA spectral indices between low (≲1.8) and high (≳1.8) values, as well as the distribution of ENA spectral indices at high and low latitudes, correlates well with the evolution of the fast and slow solar wind latitudinal structure observed near 1 au. This correlation includes a delay due to the time it takes the solar wind to propagate to the termination shock and into the inner heliosheath, and for ENAs to be generated via charge-exchange and travel back toward 1 au. Moreover, we observe a temporal asymmetry in the steepening of the ENA spectrum in the northern and southern hemispheres, consistent with asymmetries observed in the solar wind and polar coronal holes. While this asymmetry is observed near the upwind direction of the heliosphere, it is not yet observed in the tail direction, suggesting a longer line-of-sight integration distance or different processing of the solar wind plasma downstream of the termination shock.

  5. Iterative inversion of global magnetospheric ion distributions using energetic neutral atom (ENA images recorded by the NUADU/TC2 instrument

    Directory of Open Access Journals (Sweden)

    L. Lu

    2008-06-01

    Full Text Available A method has been developed for extracting magnetospheric ion distributions from Energetic Neutral Atom (ENA measurements made by the NUADU instrument on the TC-2 spacecraft. Based on a constrained linear inversion, this iterative technique is suitable for use in the case of an ENA image measurement, featuring a sharply peaked spatial distribution. The method allows for magnetospheric ion distributions to be extracted from a low-count ENA image recorded over a short integration time (5 min. The technique is demonstrated through its application to a set of representative ENA images recorded in energy Channel~2 (hydrogen: 50–81 keV, oxygen: 138–185 keV of the NUADU instrument during a geomagnetic storm. It is demonstrated that this inversion method provides a useful tool for extracting ion distribution information from ENA data that are characterized by high temporal and spatial resolution. The recovered ENA images obtained from inverted ion fluxes match most effectively the measurements made at maximum ENA intensity.

  6. Measurements of plasma temperature and electron density in laser-induced copper plasma by time-resolved spectroscopy of neutral atom and ion emissions

    Indian Academy of Sciences (India)

    V K Unnikrishnan; Kamlesh Alti; V B Kartha; C Santhosh; G P Gupta; B M Suri

    2010-06-01

    Plasma produced by a 355 nm pulsed Nd:YAG laser with a pulse duration of 6 ns focussed onto a copper solid sample in air at atmospheric pressure is studied spectroscopically. The temperature and electron density characterizing the plasma are measured by time-resolved spectroscopy of neutral atom and ion line emissions in the time window of 300–2000 ns. An echelle spectrograph coupled with a gated intensified charge coupled detector is used to record the plasma emissions. The temperature is obtained using the Boltzmann plot method and the electron density is determined using the Saha– Boltzmann equation method. Both parameters are studied as a function of delay time with respect to the onset of the laser pulse. The results are discussed. The time window where the plasma is optically thin and is also in local thermodynamic equilibrium (LTE), necessary for the laser-induced breakdown spectroscopy (LIBS) analysis of samples, is deduced from the temporal evolution of the intensity ratio of two Cu I lines. It is found to be 700–1000 ns.

  7. X-ray-induced DNA double-strand breaks in mouse l1210 cells: a new computational method for analyzing neutral filter elution data.

    Science.gov (United States)

    Cedervall, Björn; Edgren, Margareta R; Lewensohn, Rolf

    2003-04-01

    The aim of this article is to present a method for studying the shape of the dose and repair responses for X-ray-induced double-strand breaks (DSBs) as measured by neutral filter elution (NFE). The approach is closely related to a method we developed for the use of specific molecular size markers and used for determination of the absolute number of randomly distributed radiation-induced DSBs by pulsed-field gel electrophoresis (PFGE). Mouse leukemia L1210 cells were X-irradiated with 0-50 Gy. Samples were then evaluated both with PFGE and with NFE. Assuming that with both migration (PFGE) and elution (NFE), a heterogeneous population of double-stranded DNA fragments will start with the smallest fragments and proceed with increasingly larger fragments, it is possible to match the migration behavior of fractions of fragments smaller than a certain size to the fraction eluted at a specific time. This assumption does not exclude the possibility of DNA being sheared in the NFE filter. The yield, as determined by the size markers in PFGE, was used to find the corresponding elution times in the NFE experiment. These experimentally used elution times could then reversely be interpreted as size markers which finally were used to calculate DSBs/Mbp as a function of X-ray dose. The resulting lines were almost straight. The data were also plotted as relative elution and showed that, as expected, the dose response then appears with a more pronounced sigmoid shape.

  8. Multiconfiguration Dirac-Hartree-Fock energy levels, oscillator strengths, transition probabilities, hyperfine constants and Landé g-factor of intermediate Rydberg series in neutral argon atom

    Science.gov (United States)

    Salah, Wa'el; Hassouneh, Ola

    2017-04-01

    We computed the energy levels, oscillator strengths f_{ij}, the radiative transition rates A_{ij}, the Landé g -factor, the magnetic dipole moment and the electric quadrupole hyperfine constants of the intermediate Rydberg series ns [k]J ( 4 ≤ n ≤ 6), nd [k]J (3 ≤ n ≤ 4), np [k]J (4 ≤ n ≤ 5) relative to the ground state 3p6 1S0 for neutral argon atom spectra. The values are obtained in the framework of the multiconfiguration Dirac-Hartree-Fock (MCDHF) approach. In this approach, Breit interaction, leading quantum electrodynamics (QED) effects and self-energy correction are taken into account. Moreover, these spectroscopic parameters have been calculated for many levels belonging to the configuration 3p54s, 3p55s, 3p56s, 3p53d, 3p54d, 3p54p, 3p55p as well as for transitions between levels 3p54s-3p54p, 3p54p-3p53d, 3p54p-3p55s, 3p55s-3p55p and 3p55p-3p56s. The large majority of the lines from the 4p-5s and 4p-3d, 5s-5p and 5p-6s transition arrays have been observed and the calculations are consistent with the J -file-sum rule. The obtained theoretical values are compared with previous experimental and theoretical data available in the literature. An overall satisfactory agreement is noticed allowing assessing the reliability of our data.

  9. Atomic parity violation, muon pair production in e{sup +}e{sup -} collisions, and detection of CDM WIMP. Physics related to the neutral vector boson D{sub 1}

    Energy Technology Data Exchange (ETDEWEB)

    Senju, Hirofumi [Physics Department, School of Design and Architecture, Nagoya City Univ., Nagoya (Japan)

    1999-11-01

    In our preon model there exists a neutral vector boson D{sub 1} which is an isoscalar partner of W(Z) in the vector boson octet. It is shown that the exchange of a D{sub 1} of about 1 TeV mass naturally explains a positive excess of the weak charge of atomic cesium recently observed. Other processes occurring through the D{sub 1} exchange are discussed, including the detection of CDM WIMP. (author)

  10. Limited Neutrality

    DEFF Research Database (Denmark)

    Nielsen, Morten Ebbe Juul

    2006-01-01

    Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."......Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."...

  11. Limited Neutrality

    DEFF Research Database (Denmark)

    Nielsen, Morten Ebbe Juul

    2006-01-01

    Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."......Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."...

  12. Quantum computing implementations with neutral particles

    DEFF Research Database (Denmark)

    Negretti, Antonio; Treutlein, Philipp; Calarco, Tommaso

    2011-01-01

    We review quantum information processing with cold neutral particles, that is, atoms or polar molecules. First, we analyze the best suited degrees of freedom of these particles for storing quantum information, and then we discuss both single- and two-qubit gate implementations. We focus our discu...... optimal control theory might be a powerful tool to enhance the speed up of the gate operations as well as to achieve high fidelities required for fault tolerant quantum computation.......We review quantum information processing with cold neutral particles, that is, atoms or polar molecules. First, we analyze the best suited degrees of freedom of these particles for storing quantum information, and then we discuss both single- and two-qubit gate implementations. We focus our...... discussion mainly on collisional quantum gates, which are best suited for atom-chip-like devices, as well as on gate proposals conceived for optical lattices. Additionally, we analyze schemes both for cold atoms confined in optical cavities and hybrid approaches to entanglement generation, and we show how...

  13. Spectroscopy of neutral radium

    Energy Technology Data Exchange (ETDEWEB)

    Mol, Aran; De, Subhadeep; Jungmann, Klaus; Wilschut, Hans; Willmann, Lorenz [KVI, University of Groningen, Groningen (Netherlands)

    2008-07-01

    The heavy alkaline earth atoms radium is uniquely sensitive towards parity and time reversal symmetry violations due to a large enhancement of an intrinsic permanent electric dipole moment of the nucleous or the electron. Furthermore, radium is sensitive to atomic parity violation and the nuclear anapole moment. To prepare such experiments spectroscopy of relevant atomic states need to be done. At a later stage we will build a neutral atom trap for radium. We have built an atomic beam of the short lived isotope {sup 225}Ra with a flux of several 10{sup 4} atoms/sec. We are preparing the laser spectroscopy using this beam setup. In the preparation for efficient laser cooling and trapping we have successfully trapped barium, which is similar in it's requirements for laser cooling. The techniques which we have developed with barium can be used to trap rare radium isotopes. We report on the progress of the experiments.

  14. Plasma/Neutral-Beam Etching Apparatus

    Science.gov (United States)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  15. Plasma/Neutral-Beam Etching Apparatus

    Science.gov (United States)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  16. Solute and solvent dynamics in confined equal-sized aqueous environments of charged and neutral reverse micelles: a combined dynamic fluorescence and all-atom molecular dynamics simulation study.

    Science.gov (United States)

    Guchhait, Biswajit; Biswas, Ranjit; Ghorai, Pradip K

    2013-03-28

    Here a combined dynamic fluorescence and all-atom molecular dynamics simulation study of aqueous pool-size dependent solvation energy and rotational relaxations of a neutral dipolar solute, C153, trapped in AOT (charged) and IGPAL (neutral) reverse micelles (RMs) at 298 K, is described. RMs in simulations have been represented by a reduced model where SPC/E water molecules interact with a trapped C153 that possesses realistic charge distributions for both ground and excited states. In large aqueous pools, measured average solvation and rotation rates are smaller for the neutral RMs than those in charged ones. Interestingly, while the measured average solvation and rotation rates increase with pool size for the charged RMs, the average rotation rates for the neutral RMs exhibit a reverse dependence. Simulations have qualitatively reproduced this experimental trend and suggested interfacial location for the solute for all cases. The origin for the subnanosecond Stokes shift dynamics has been investigated and solute-interface interaction contribution quantified. Simulated layer-wise translational and rotational diffusions of water molecules re-examine the validity of the core-shell model and provide a resolution to a debate regarding the origin of the subnanosecond solvation component in dynamic Stokes shift measurements with aqueous RMs but not detected in ultrafast IR measurements.

  17. Facile distinction of neutral and acidic tetraether lipids in archaea membrane by halogen atom adduct ions in electrospray ionization mass spectrometry.

    Science.gov (United States)

    Murae, Tatsushi; Takamatsu, Yuichiro; Muraoka, Ryohei; Endoh, Satoshi; Yamauchi, Noriaki

    2002-02-01

    Calditocaldarchaeol (neutral tetraether lipid) from Sulfolobus acidocaldarius (acidothermophilic archaea) and intact total lipid from the thermoacidophilic archaea Sulfolobus sp. was examined by electrospray ionization time-of-flight mass spectrometry in the negative-ion mode using high resolution. When the sample was injected as a solution in a 3:1 mixture of methanol (MeOH) and chloroform (CHCl(3)) using an infusion system, the total ether lipid afforded molecular-related ions as [M - H](-) for acidic polar lipids containing a phosphoric or sulfuric group, and as [M + Cl](-) ion for neutral glycolipids. The attachment of chloride was confirmed by the observation of [M + Br](-) ion, instead of [M + Cl](-) ion, when a 3:1 mixture of MeOH and CHBr(3) was used in place of MeOH-CHCl(3) as the solvent. The composition of tetraether neutral glycolipids that are different from each other only in the number of five-membered rings in the isoprenoid chain was determined on the basis of the isotope-resolved mass spectrum of [M + Cl](-) ions. As for acidic tetraether lipids, molecular-related ions [M - H](-)) were not observed when the 3:1 MeOH-CHBr(3) mixture was used as the solvent. These results together afforded a facile method of distinguishing neutral from acidic tetraether lipids in intact total lipids of acidothermophilic archaea. This method was applied to determine the difference of the number of five-membered rings in isoprenyl chains of neutral tetraether glycolipids yielded by the Sulfolobus sp. grown at different temperatures. Discrimination of neutral tetraether glycolipids from acidic tetraether lipids in the total lipids obtained from Thermoplasma sp. was also achieved by this method.

  18. Deterministic Entanglement via Molecular Dissociation in Integrated Atom Optics

    OpenAIRE

    Zhao, Bo; Chen, Zeng-Bing; Pan, Jian-Wei; Schmiedmayer, J.; Recati, Alessio; Astrakharchik, Grigory E.; Calarco, Tommaso

    2005-01-01

    Deterministic entanglement of neutral cold atoms can be achieved by combining several already available techniques like the creation/dissociation of neutral diatomic molecules, manipulating atoms with micro fabricated structures (atom chips) and detecting single atoms with almost 100% efficiency. Manipulating this entanglement with integrated/linear atom optics will open a new perspective for quantum information processing with neutral atoms.

  19. Ultracold Neutral Plasmas

    CERN Document Server

    Killian, T C; Gupta, P; Laha, S; Martinez, Y N; Mickelson, P G; Nagel, S B; Saenz, A D; Simien, C E; Killian, Thomas C.

    2005-01-01

    Ultracold neutral plasmas are formed by photoionizing laser-cooled atoms near the ionization threshold. Through the application of atomic physics techniques and diagnostics, these experiments stretch the boundaries of traditional neutral plasma physics. The electron temperature in these plasmas ranges from 1-1000 K and the ion temperature is around 1 K. The density can approach $10^{11}$ cm$^{-3}$. Fundamental interest stems from the possibility of creating strongly-coupled plasmas, but recombination, collective modes, and thermalization in these systems have also been studied. Optical absorption images of a strontium plasma, using the Sr$^+$ ${^2S_{1/2}} -> {^2P_{1/2}}$ transition at 422 nm, depict the density profile of the plasma, and probe kinetics on a 50 ns time-scale. The Doppler-broadened ion absorption spectrum measures the ion velocity distribution, which gives an accurate measure of the ion dynamics in the first microsecond after photoionization.

  20. [The content of mineral elements in Camellia olei fera ovary at pollination and fertilization stages determined by auto discrete analyzers and atomic absorption spectrophotometer].

    Science.gov (United States)

    Zou, Feng; Yuan, De-Yi; Gao, Chao; Liao, Ting; Chen, Wen-Tao; Han, Zhi-Qiang; Zhang, Lin

    2014-04-01

    In order to elucidate the nutrition of Camellia olei fera at pollination and fertilization stages, the contents of mineral elements were determined by auto discrete analyzers and atomic absorption spectrophotometer, and the change in the contents of mineral elements was studied and analysed under the condition of self- and cross-pollination. The results are showed that nine kinds of mineral elements contents were of "S" or "W" type curve changes at the pollination and fertilization stages of Camellia olei fera. N, K, Zn, Cu, Ca, Mn element content changes showed "S" curve under the self- and out-crossing, the content of N reaching the highest was 3.445 8 mg x g(-1) in self-pollination of 20 d; K content reaching the highest at the cross-pollination 20 d was 6.275 5 mg x g(-1); Zn content in self-pollination of 10 d reaching the highest was 0.070 5 mg x g(-1); Cu content in the cross-pollination of 5 d up to the highest was 0.061 0 mg x g(-1); Ca content in the cross-pollination of 15 d up to the highest was 3.714 5 mg x g(-1); the content of Mn reaching the highest in self-pollination 30 d was 2. 161 5 mg x g(-1). Fe, P, Mg element content changes was of "S" type curve in selfing and was of "W" type curve in outcrossing, Fe content in the self-pollination 10 d up to the highest was 0.453 0 mg x g(-1); P content in self-pollination of 20 d reaching the highest was 6.731 8 mg x g(-1); the content of Mg up to the highest in self-pollination 25 d was 2.724 0 mg x g(-1). The results can be used as a reference for spraying foliar fertilizer, and improving seed setting rate and yield in Camellia olei fera.

  1. Ultracold neutral plasmas

    Science.gov (United States)

    Lyon, M.; Rolston, S. L.

    2017-01-01

    By photoionizing samples of laser-cooled atoms with laser light tuned just above the ionization limit, plasmas can be created with electron and ion temperatures below 10 K. These ultracold neutral plasmas have extended the temperature bounds of plasma physics by two orders of magnitude. Table-top experiments, using many of the tools from atomic physics, allow for the study of plasma phenomena in this new regime with independent control over the density and temperature of the plasma through the excitation process. Characteristic of these systems is an inhomogeneous density profile, inherited from the density distribution of the laser-cooled neutral atom sample. Most work has dealt with unconfined plasmas in vacuum, which expand outward at velocities of order 100 m/s, governed by electron pressure, and with lifetimes of order 100 μs, limited by stray electric fields. Using detection of charged particles and optical detection techniques, a wide variety of properties and phenomena have been observed, including expansion dynamics, collective excitations in both the electrons and ions, and collisional properties. Through three-body recombination collisions, the plasmas rapidly form Rydberg atoms, and clouds of cold Rydberg atoms have been observed to spontaneously avalanche ionize to form plasmas. Of particular interest is the possibility of the formation of strongly coupled plasmas, where Coulomb forces dominate thermal motion and correlations become important. The strongest impediment to strong coupling is disorder-induced heating, a process in which Coulomb energy from an initially disordered sample is converted into thermal energy. This restricts electrons to a weakly coupled regime and leaves the ions barely within the strongly coupled regime. This review will give an overview of the field of ultracold neutral plasmas, from its inception in 1999 to current work, including efforts to increase strong coupling and effects on plasma properties due to strong coupling.

  2. Nuclear spin dependent parity violating electron-nucleus interaction in heavy atoms. The anapole moment and the perturbation of the hadronic vector neutral current by the hyperfine interaction

    Energy Technology Data Exchange (ETDEWEB)

    Bouchiat, C.; Piketty, C.A. (Lab. de Physique Theorique, Ecole Normale Superieure, 75 - Paris (France))

    1991-10-24

    We present first a computation of the nuclear anapole moment of thallium by a method developed previously by the authors. Then we perform a detailed analysis of the spin dependent parity violating electron-nucleon potential generated by the hyperfine coupling perturbation upon the pseudoscalar interaction of the electron with the weak charge of the nucleus. This effect is found to be of order {alpha}G{sub F}A{sup 2/3} and represents, depending upon the nucleus, (10-70)% of the anapole moment contribution. In the case of thallium, it compensates almost exactly the contribution associated with the axial hadronic neutral current. This fact, together with other arguments given in the paper, makes thallium a favoured candidate for the anapole moment search provided accurate enough experiments can be performed. (orig.).

  3. Nuclear spin dependent parity violating electron-nucleus interaction in heavy atoms. The anapole moment and the perturbation of the hadronic vector neutral current by the hyperfine interaction

    Science.gov (United States)

    Bouchiat, C.; Piketty, C. A.

    1991-10-01

    We present first a computation of the nuclear anapole moment of thallium by a method developed previously by the authors. Then we perform a detailed analysis of the spin dependent parity violating electron-nucleon potential generated by the hyperfine coupling perturbation upon the pseudoscalar interaction of the electron with the weak charge of the nucleus. This effect is found to be of order αG FA {2}/{3} and represents, depending upon the nucleus, (10-70)% of the anapole moment contribution. In the case of thallium, it compensates almost exactly the contribution associated with the axial hadronic neutral current. This fact, together with other arguments given in the paper, makes thallium a favoured candidate for the anapole moment search provided accurate enough experiments can be performed.

  4. Implementation of a 3D halo neutral model in the TRANSP code and application to projected NSTX-U plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Medley, S. S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Liu, D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy; Gorelenkova, M. V. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Heidbrink, W. W. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy; Stagner, L. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy

    2016-01-12

    A 3D halo neutral code developed at the Princeton Plasma Physics Laboratory and implemented for analysis using the TRANSP code is applied to projected National Spherical Torus eXperiment-Upgrade (NSTX-U plasmas). The legacy TRANSP code did not handle halo neutrals properly since they were distributed over the plasma volume rather than remaining in the vicinity of the neutral beam footprint as is actually the case. The 3D halo neutral code uses a 'beam-in-a-box' model that encompasses both injected beam neutrals and resulting halo neutrals. Upon deposition by charge exchange, a subset of the full, one-half and one-third beam energy components produce first generation halo neutrals that are tracked through successive generations until an ionization event occurs or the descendant halos exit the box. The 3D halo neutral model and neutral particle analyzer (NPA) simulator in the TRANSP code have been benchmarked with the Fast-Ion D-Alpha simulation (FIDAsim) code, which provides Monte Carlo simulations of beam neutral injection, attenuation, halo generation, halo spatial diffusion, and photoemission processes. When using the same atomic physics database, TRANSP and FIDAsim simulations achieve excellent agreement on the spatial profile and magnitude of beam and halo neutral densities and the NPA energy spectrum. The simulations show that the halo neutral density can be comparable to the beam neutral density. These halo neutrals can double the NPA flux, but they have minor effects on the NPA energy spectrum shape. The TRANSP and FIDAsim simulations also suggest that the magnitudes of beam and halo neutral densities are relatively sensitive to the choice of the atomic physics databases.

  5. Implementation of a 3D halo neutral model in the TRANSP code and application to projected NSTX-U plasmas

    Science.gov (United States)

    Medley, S. S.; Liu, D.; Gorelenkova, M. V.; Heidbrink, W. W.; Stagner, L.

    2016-02-01

    A 3D halo neutral code developed at the Princeton Plasma Physics Laboratory and implemented for analysis using the TRANSP code is applied to projected National Spherical Torus eXperiment-Upgrade (NSTX-U plasmas). The legacy TRANSP code did not handle halo neutrals properly since they were distributed over the plasma volume rather than remaining in the vicinity of the neutral beam footprint as is actually the case. The 3D halo neutral code uses a ‘beam-in-a-box’ model that encompasses both injected beam neutrals and resulting halo neutrals. Upon deposition by charge exchange, a subset of the full, one-half and one-third beam energy components produce first generation halo neutrals that are tracked through successive generations until an ionization event occurs or the descendant halos exit the box. The 3D halo neutral model and neutral particle analyzer (NPA) simulator in the TRANSP code have been benchmarked with the Fast-Ion D-Alpha simulation (FIDAsim) code, which provides Monte Carlo simulations of beam neutral injection, attenuation, halo generation, halo spatial diffusion, and photoemission processes. When using the same atomic physics database, TRANSP and FIDAsim simulations achieve excellent agreement on the spatial profile and magnitude of beam and halo neutral densities and the NPA energy spectrum. The simulations show that the halo neutral density can be comparable to the beam neutral density. These halo neutrals can double the NPA flux, but they have minor effects on the NPA energy spectrum shape. The TRANSP and FIDAsim simulations also suggest that the magnitudes of beam and halo neutral densities are relatively sensitive to the choice of the atomic physics databases.

  6. Application of atomic absorption spectrometry with continuous light source to analyze selected metals important for human health in different parts of oranges

    Directory of Open Access Journals (Sweden)

    Szwerc Wojciech

    2014-09-01

    Full Text Available The publication describes the application of high-resolution continuum source atomic absorption spectrometry (H-R CS AAS to determine some physiologically essential and toxic elements occurring in citrus fruits of different origins. Before analysis, the samples were mineralized using a mixture of deionized water and 69% nitric acid 3:1 (v/v in high pressure microwave digestion at 188°C during one hour.

  7. Constraining the Europa Neutral Torus

    Science.gov (United States)

    Smith, Howard T.; Mitchell, Donald; mauk, Barry; Johnson, Robert E.; clark, george

    2016-10-01

    "Neutral tori" consist of neutral particles that usually co-orbit along with their source forming a toroidal (or partial toroidal) feature around the planet. The distribution and composition of these features can often provide important, if not unique, insight into magnetospheric particles sources, mechanisms and dynamics. However, these features can often be difficult to directly detect. One innovative method for detecting neutral tori is by observing Energetic Neutral Atoms (ENAs) that are generally considered produced as a result of charge exchange interactions between charged and neutral particles.Mauk et al. (2003) reported the detection of a Europa neutral particle torus using ENA observations. The presence of a Europa torus has extremely large implications for upcoming missions to Jupiter as well as understanding possible activity at this moon and providing critical insight into what lies beneath the surface of this icy ocean world. However, ENAs can also be produced as a result of charge exchange interactions between two ionized particles and in that case cannot be used to infer the presence of neutral particle population. Thus, a detailed examination of all possible source interactions must be considered before one can confirm that likely original source population of these ENA images is actually a Europa neutral particle torus. For this talk, we examine the viability that the Mauk et al. (2003) observations were actually generated from a neutral torus emanating from Europa as opposed to charge particle interactions with plasma originating from Io. These results help constrain such a torus as well as Europa source processes.

  8. Neutral evolution of mutational robustness.

    NARCIS (Netherlands)

    Nimwegen, E. van; Crutchfield, J.P.; Huynen, M.A.

    1999-01-01

    We introduce and analyze a general model of a population evolving over a network of selectively neutral genotypes. We show that the population's limit distribution on the neutral network is solely determined by the network topology and given by the principal eigenvector of the network's adjacency ma

  9. Neutral Evolution of Mutational Robustness

    CERN Document Server

    Van Nimwegen, E; Huynen, M; Nimwegen, Erik van; Crutchfield, James P.; Huynen, Martijn

    1999-01-01

    We introduce and analyze a general model of a population evolving over a network of selectively neutral genotypes. We show that the population's limit distribution on the neutral network is solely determined by the network topology and given by the principal eigenvector of the network's adjacency matrix. Moreover, the average number of neutral mutant neighbors per individual is given by the matrix spectral radius. This quantifies the extent to which populations evolve mutational robustness: the insensitivity of the phenotype to mutations. Since the average neutrality is independent of evolutionary parameters---such as, mutation rate, population size, and selective advantage---one can infer global statistics of neutral network topology using simple population data available from {\\it in vitro} or {\\it in vivo} evolution. Populations evolving on neutral networks of RNA secondary structures show excellent agreement with our theoretical predictions.

  10. Fast transport, atom sample splitting, and single-atom qubit supply in two-dimensional arrays of optical microtraps

    CERN Document Server

    Schlosser, Malte; Gierl, Christian; Teichmann, Stephan; Tichelmann, Sascha; Birkl, Gerhard; 10.1088/1367-2630/14/12/123034

    2013-01-01

    Two-dimensional arrays of optical micro-traps created by microoptical elements present a versatile and scalable architecture for neutral atom quantum information processing, quantum simulation, and the manipulation of ultra-cold quantum gases. In this article, we demonstrate advanced capabilities of this approach by introducing novel techniques and functionalities as well as the combined operation of previously separately implemented functions. We introduce piezo-actuator based transport of atom ensembles over distances of more than one trap separation, examine the capabilities of rapid atom transport provided by acousto-optical beam steering, and analyze the adiabaticity limit for atom transport in these configurations. We implement a spatial light modulator with 8-bit transmission control for the per-site adjustment of the trap depth and the number of atoms loaded. We combine single-site addressing, trap depth control, and atom transport in one configuration for demonstrating the splitting of atom ensembles...

  11. Simultaneous determination of mercury and organic carbon in sediment and soils using a direct mercury analyzer based on thermal decomposition–atomic absorption spectrophotometry

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jingjing [College of Chemical Engineering, Zhejiang University of Technology, No. 18 Chaowang Road, Hangzhou, Zhejiang 310032 (China); Chakravarty, Pragya [Department of Chemistry and Biochemistry, University of Mississippi, University, MS 38677 (United States); Davidson, Gregg R. [Department of Geology and Geological Engineering, University of Mississippi, University, MS 38677 (United States); Wren, Daniel G.; Locke, Martin A. [National Sedimentation Laboratory, United States Department of Agriculture, Agricultural Research Service, Oxford, MS 38655 (United States); Zhou, Ying, E-mail: yingzhou@zjut.edu.cn [College of Chemical Engineering, Zhejiang University of Technology, No. 18 Chaowang Road, Hangzhou, Zhejiang 310032 (China); Brown, Garry [Department of Chemistry and Biochemistry, University of Mississippi, University, MS 38677 (United States); Cizdziel, James V., E-mail: cizdziel@olemiss.edu [Department of Chemistry and Biochemistry, University of Mississippi, University, MS 38677 (United States)

    2015-04-29

    Graphical abstract: Comparison of LOI data obtained by a conventional method and by the DMA. The dark line represents a 1:1 ratio. - Highlights: • A direct mercury analyzer was used to estimate total organic carbon. • Mercury and organic carbon were measured in oxbow lake sediment cores. • Temporal and spatial deposition of Hg in the Mississippi Delta were evaluated. - Abstract: The purpose of this work was to study the feasibility of using a direct mercury analyzer (DMA) to simultaneously determine mercury (Hg) and organic matter content in sediment and soils. Organic carbon was estimated by re-weighing the sample boats post analysis to obtain loss-on-ignition (LOI) data. The DMA-LOI results were statistically similar (p < 0.05) to the conventional muffle furnace approach. A regression equation was developed to convert DMA-LOI data to total organic carbon (TOC), which varied between 0.2% and 13.0%. Thus, mercury analyzers based on combustion can provide accurate estimates of organic carbon content in non-calcareous sediment and soils; however, weight gain from moisture (post-analysis), measurement uncertainty, and sample representativeness should all be taken into account. Sediment cores from seasonal wetland and open water areas from six oxbow lakes in the Mississippi River alluvial flood plain were analyzed. Wetland sediments generally had higher levels of Hg than open water areas owing to a greater fraction of fine particles and higher levels of organic matter. Annual loading of Hg in open water areas was estimated at 4.3, 13.4, 19.2, 20.7, 129, and 135 ng cm{sup −2} yr{sup −1} for Beasley, Roundaway, Hampton, Washington, Wolf and Sky Lakes, respectively. Generally, the interval with the highest Hg flux was dated to the 1960s and 1970s.

  12. Simultaneous determination of mercury and organic carbon in sediment and soils using a direct mercury analyzer based on thermal decomposition-atomic absorption spectrophotometry.

    Science.gov (United States)

    Chen, Jingjing; Chakravarty, Pragya; Davidson, Gregg R; Wren, Daniel G; Locke, Martin A; Zhou, Ying; Brown, Garry; Cizdziel, James V

    2015-04-29

    The purpose of this work was to study the feasibility of using a direct mercury analyzer (DMA) to simultaneously determine mercury (Hg) and organic matter content in sediment and soils. Organic carbon was estimated by re-weighing the sample boats post analysis to obtain loss-on-ignition (LOI) data. The DMA-LOI results were statistically similar (p<0.05) to the conventional muffle furnace approach. A regression equation was developed to convert DMA-LOI data to total organic carbon (TOC), which varied between 0.2% and 13.0%. Thus, mercury analyzers based on combustion can provide accurate estimates of organic carbon content in non-calcareous sediment and soils; however, weight gain from moisture (post-analysis), measurement uncertainty, and sample representativeness should all be taken into account. Sediment cores from seasonal wetland and open water areas from six oxbow lakes in the Mississippi River alluvial flood plain were analyzed. Wetland sediments generally had higher levels of Hg than open water areas owing to a greater fraction of fine particles and higher levels of organic matter. Annual loading of Hg in open water areas was estimated at 4.3, 13.4, 19.2, 20.7, 129, and 135 ng cm(-2) yr(-1) for Beasley, Roundaway, Hampton, Washington, Wolf and Sky Lakes, respectively. Generally, the interval with the highest Hg flux was dated to the 1960s and 1970s. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. New level-resolved collision data for neutral argon, benchmarked against the ALEXIS plasma experiment

    Science.gov (United States)

    Arnold, Nicholas; Loch, Stuart; Ballance, Connor; Thomas, Ed

    2016-10-01

    Performing spectroscopic measurements of emission lines in low temperature laboratory plasmas is challenging because the plasma is often neutral-dominated and not in thermal equilibrium. The densities and temperatures are such that coronal models do not apply; meaning that generalized collisional-radiative (GCR) methods must be employed to theoretically analyze atomic processes. However, for most noble gases, detailed, level-resolved atomic data for neutral and low-charge states does not exist in the literature. We report on a new project, where we use existing atomic physics codes to calculate level-resolved atomic data for neutral and low charge states of argon and compare with previously published, term-resolved theoretical results. In addition, we use the Atomic Structure and Data Analysis (ADAS) suite of codes to calculate a GCR model for low temperature neutral argon, which we compare to published measurements of argon optical emission cross sections. Finally, we compare synthetic spectra generated from our data with observations taken from the Auburn Linear Experiment for Instability Studies (ALEXIS) in an attempt to develop new optical plasma diagnostics for electron temperature and plasma density measurements. This project is supported by the U.S. Department of Energy. Grant Number: DE-FG02-00ER54476.

  14. Analyzing the Effect of Capillary Force on Vibrational Performance of the Cantilever of an Atomic Force Microscope in Tapping Mode with Double Piezoelectric Layers in an Air Environment.

    Science.gov (United States)

    Nahavandi, Amir; Korayem, Moharam Habibnejad

    2015-10-01

    The aim of this paper is to determine the effects of forces exerted on the cantilever probe tip of an atomic force microscope (AFM). These forces vary according to the separation distance between the probe tip and the surface of the sample being examined. Hence, at a distance away from the surface (farther than d(on)), these forces have an attractive nature and are of Van der Waals type, and when the probe tip is situated in the range of a₀≤ d(ts) ≤ d(on), the capillary force is added to the Van der Waals force. At a distance of d(ts) ≤ a₀, the Van der Waals and capillary forces remain constant at intermolecular distances, and the contact repulsive force repels the probe tip from the surface of sample. The capillary force emerges due to the contact of thin water films with a thickness of h(c) which have accumulated on the sample and probe. Under environmental conditions a layer of water or hydrocarbon often forms between the probe tip and sample. The capillary meniscus can grow until the rate of evaporation equals the rate of condensation. For each of the above forces, different models are presented. The smoothness or roughness of the surfaces and the geometry of the cantilever tip have a significant effect on the modeling of forces applied on the probe tip. Van der Waals and the repulsive forces are considered to be the same in all the simulations, and only the capillary force is altered in order to evaluate the role of this force in the AFM-based modeling. Therefore, in view of the remarkable advantages of the piezoelectric microcantilever and also the extensive applications of the tapping mode, we investigate vibrational motion of the piezoelectric microcantilever in the tapping mode. The cantilever mentioned is entirely covered by two piezoelectric layers that carry out both the actuation of the probe tip and the measuringof its position.

  15. Microfabricated Waveguide Atom Traps.

    Energy Technology Data Exchange (ETDEWEB)

    Jau, Yuan-Yu

    2017-09-01

    A nano - scale , microfabricated waveguide structure can in - principle be used to trap atoms in well - defined locations and enable strong photon - atom interactions . A neutral - atom platf orm based on this microfabrication technology will be pre - aligned , which is especially important for quantum - control applications. At present, there is still no reported demonstration of evanescent - field atom trapping using a microfabricated waveguide structure. We described the capabilities established by our team for future development of the waveguide atom - trapping technology at SNL and report our studies to overcome the technical challenges of loading cold atoms into the waveguide atom traps, efficient and broadband optical coupling to a waveguide, and the waveguide material for high - power optical transmission. From the atomic - physics and the waveguide modeling, w e have shown that a square nano - waveguide can be utilized t o achieve better atomic spin squeezing than using a nanofiber for first time.

  16. Cooling and Trapping of Neutral Atoms

    Science.gov (United States)

    2009-04-30

    for 5 < 0. A plot of E± is shown in Fig. 1 showing these limits near the FIG 1: A Plot of £±- The dressed states com- n = 0 plane . These bare...Lett. 96, 253001 (2006). [43] M. E. Carrera -Patio and R. S. Berry, Phys. Rev. A 34, 4728 (1986). [44] S. van Enk and G. Nienhuis, Phys. Rev. A 46, 1438 (1992).

  17. Characterizing optical dipole trap via fluorescence of trapped cesium atoms

    Institute of Scientific and Technical Information of China (English)

    LIU Tao; GENG Tao; YAN Shubin; LI Gang; ZHANG Jing; WANG Junmin; PENG Kunchi; ZHANG Tiancai

    2006-01-01

    Optical dipole trap (ODT) is becoming an important tool of manipulating neutral atoms. In this paper ODT is realized with a far-off resonant laser beam strongly focused in the magneto-optical trap (MOT) of cesium atoms. The light shift is measured by simply monitoring the fluorescence of the atoms in the magneto-optical trap and the optical dipole trap simultaneously. The advantages of our experimental scheme are discussed, and the effect of the beam waist and power on the potential of dipole trap as well as heating rate is analyzed.

  18. Collisional Thermalization in Strongly Coupled Ultracold Neutral Plasmas

    Science.gov (United States)

    2017-01-25

    ultracold neutral plasmas, which are formed by photoionizing laser cooled atoms. These are the coldest neutral plasmas every created, and they allow...and received the “Editors’ Suggestion” distinction. We also completed numerical modeling of laser cooling a neutral plasma and construction of the...We also had to install several laser systems for driving the laser - cooling transitions in the ions and for repumping atoms out of dark states

  19. Primary neutral helium in the heliosphere

    CERN Document Server

    Mueller, Hans-Reinhard

    2012-01-01

    Two years of neutral measurements by IBEX-Lo have yielded several direct observations of interstellar neutral helium and oxygen during preferred viewing seasons. Besides the interstellar signal, there are indications of the presence of secondary neutral helium and oxygen created in the heliosphere. Detailed modeling of these particle species is necessary to connect the measured fluxes to the pristine local interstellar medium while accounting for loss and production of neutral particles during their path through the heliosphere. In this contribution, global heliosphere models are coupled to analytic calculations of neutral trajectories to obtain detailed estimates of the neutral distribution function of primary interstellar helium atoms in the heliosphere, in particular in the inner heliosphere.

  20. What is Neutrality?

    NARCIS (Netherlands)

    Pierik, R.; van der Burg, W.

    2014-01-01

    This paper reinvestigates the question of liberal neutrality. We contend that current liberal discussions have been dominated - if not hijacked - by one particular interpretation of what neutrality could imply, namely, exclusive neutrality, that aims to exclude religious and cultural expressions

  1. High-altitude atomic nitrogen densities

    Science.gov (United States)

    Oran, E. S.; Strobel, D. F.; Mauersberger, K.

    1978-01-01

    Theoretical calculations of the seasonal and diurnal variations of atomic nitrogen are compared with measurements made by the open source neutral mass spectrometer on the AE-C satellite. With the simultaneous measurements of molecular nitrogen and atomic oxygen densities as input, model calculations of odd nitrogen densities predict the same trends in atomic nitrogen as those observed. From these comparisons it is inferred that horizontal transport significantly reduces the diurnal variation of atomic nitrogen. Estimates are given of the sensitivity of atomic nitrogen densities to variations in the photoelectron flux, the neutral temperatures, and the neutral winds.

  2. The Intermodulation Lockin Analyzer

    CERN Document Server

    Tholen, Erik A; Forchheimer, Daniel; Schuler, Vivien; Tholen, Mats O; Hutter, Carsten; Haviland, David B

    2011-01-01

    Nonlinear systems can be probed by driving them with two or more pure tones while measuring the intermodulation products of the drive tones in the response. We describe a digital lock-in analyzer which is designed explicitly for this purpose. The analyzer is implemented on a field-programmable gate array, providing speed in analysis, real-time feedback and stability in operation. The use of the analyzer is demonstrated for Intermodulation Atomic Force Microscopy. A generalization of the intermodulation spectral technique to arbitrary drive waveforms is discussed.

  3. Building and analyzing models from data by stirred tank experiments for investigation of matrix effects caused by inorganic matrices and selection of internal standards in Inductively Coupled Plasma-Atomic Emission Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Grotti, Marco [Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, 16146 Genova (Italy)], E-mail: grotti@chimica.unige.it; Paredes, Eduardo; Maestre, Salvador; Todoli, Jose Luis [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, 03080, Alicante (Spain)

    2008-05-15

    Interfering effects caused by inorganic matrices (inorganic acids as well as easily ionized elements) in inductively coupled plasma-atomic emission spectroscopy have been modeled by regression analysis of experimental data obtained using the 'stirred tank method'. The main components of the experimental set-up were a magnetically-stirred container and two peristaltic pumps. In this way the matrix composition was gradually and automatically varied, while the analyte concentration remained unchanged throughout the experiment. An inductively coupled plasma spectrometer with multichannel detection based on coupled charge device was used to simultaneously measure the emission signal at several wavelengths when the matrix concentration was modified. Up to 50 different concentrations were evaluated in a period of time of 10 min. Both single interfering species (nitric, hydrochloric and sulphuric acids, sodium and calcium) and different mixtures (aqua regia, sulfonitric mixture, sodium-calcium mixture and sodium-nitric acid mixture) were investigated. The dependence of the emission signal on acid concentration was well-fitted by logarithmic models. Conversely, for the easily ionized elements, 3-order polynomial models were more suitable to describe the trends. Then, the coefficients of these models were used as 'signatures' of the matrix-related signal variations and analyzed by principal component analysis. Similarities and differences among the emission lines were highlighted and discussed, providing a new insight into the interference phenomena, mainly with regards to the combined effect of concomitants. The combination of the huge amount of data obtained by the stirred tank method in a short period of time and the speed of analysis of principal component analysis provided a judicious means for the selection of the optimal internal standard in inductively coupled plasma-atomic emission spectroscopy.

  4. Modern atomic physics

    CERN Document Server

    Natarajan, Vasant

    2015-01-01

    Much of our understanding of physics in the last 30-plus years has come from research on atoms, photons, and their interactions. Collecting information previously scattered throughout the literature, Modern Atomic Physics provides students with one unified guide to contemporary developments in the field. After reviewing metrology and preliminary material, the text explains core areas of atomic physics. Important topics discussed include the spontaneous emission of radiation, stimulated transitions and the properties of gas, the physics and applications of resonance fluorescence, coherence, cooling and trapping of charged and neutral particles, and atomic beam magnetic resonance experiments. Covering standards, a different way of looking at a photon, stimulated radiation, and frequency combs, the appendices avoid jargon and use historical notes and personal anecdotes to make the topics accessible to non-atomic physics students. Written by a leader in atomic and optical physics, this text gives a state-of-the...

  5. Neutral Operator and Neutral Differential Equation

    Directory of Open Access Journals (Sweden)

    Jingli Ren

    2011-01-01

    Full Text Available In this paper, we discuss the properties of the neutral operator (Ax(t=x(t−cx(t−δ(t, and by applying coincidence degree theory and fixed point index theory, we obtain sufficient conditions for the existence, multiplicity, and nonexistence of (positive periodic solutions to two kinds of second-order differential equations with the prescribed neutral operator.

  6. Analyzing Orientations

    Science.gov (United States)

    Ruggles, Clive L. N.

    Archaeoastronomical field survey typically involves the measurement of structural orientations (i.e., orientations along and between built structures) in relation to the visible landscape and particularly the surrounding horizon. This chapter focuses on the process of analyzing the astronomical potential of oriented structures, whether in the field or as a desktop appraisal, with the aim of establishing the archaeoastronomical "facts". It does not address questions of data selection (see instead Chap. 25, "Best Practice for Evaluating the Astronomical Significance of Archaeological Sites", 10.1007/978-1-4614-6141-8_25) or interpretation (see Chap. 24, "Nature and Analysis of Material Evidence Relevant to Archaeoastronomy", 10.1007/978-1-4614-6141-8_22). The main necessity is to determine the azimuth, horizon altitude, and declination in the direction "indicated" by any structural orientation. Normally, there are a range of possibilities, reflecting the various errors and uncertainties in estimating the intended (or, at least, the constructed) orientation, and in more formal approaches an attempt is made to assign a probability distribution extending over a spread of declinations. These probability distributions can then be cumulated in order to visualize and analyze the combined data from several orientations, so as to identify any consistent astronomical associations that can then be correlated with the declinations of particular astronomical objects or phenomena at any era in the past. The whole process raises various procedural and methodological issues and does not proceed in isolation from the consideration of corroborative data, which is essential in order to develop viable cultural interpretations.

  7. Atom trap trace analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Z.-T.; Bailey, K.; Chen, C.-Y.; Du, X.; Li, Y.-M.; O' Connor, T. P.; Young, L.

    2000-05-25

    A new method of ultrasensitive trace-isotope analysis has been developed based upon the technique of laser manipulation of neutral atoms. It has been used to count individual {sup 85}Kr and {sup 81}Kr atoms present in a natural krypton sample with isotopic abundances in the range of 10{sup {minus}11} and 10{sup {minus}13}, respectively. The atom counts are free of contamination from other isotopes, elements,or molecules. The method is applicable to other trace-isotopes that can be efficiently captured with a magneto-optical trap, and has a broad range of potential applications.

  8. Neutral Buoyancy Laboratory (NBL)

    Data.gov (United States)

    Federal Laboratory Consortium — The Neutral Buoyancy Laboratory (NBL) is an astronaut training facility and neutral buoyancy pool operated by NASA and located at the Sonny Carter Training Facility,...

  9. Asymptotical Properties for Parabolic Systems of Neutral Type

    Institute of Scientific and Technical Information of China (English)

    CUI Bao-tong; HAN Mao-an

    2005-01-01

    Asymptotical properties for the solutions of neutral parabolic systems with Robin boundary conditions were analyzed by using the inequality analysis. The oscillations problems for the neutral parabolic systems were considered and some oscillation criteria for the systems were established.

  10. Neutron production by neutral beam sources

    Energy Technology Data Exchange (ETDEWEB)

    Berkner, K.H.; Massoletti, D.J.; McCaslin, J.B.; Pyle, R.V.; Ruby, L.

    1979-11-01

    Neutron yields, from interactions of multiampere 40- to 120-keV deuterium beams with deuterium atoms implanted in copper targets, have been measured in order to provide input data for shielding of neutral-deuterium beam facilities for magnetic fusion experiments.

  11. Effects of dark atom excitations

    CERN Document Server

    Cudell, Jean-René; Wallemacq, Quentin

    2014-01-01

    New stable quarks and charged leptons may exist and be hidden from detection, as they are bound by Coulomb interaction in neutral dark atoms of composite dark matter. This possibility leads to fundamentally new types of indirect effects related to the excitation of such dark atoms followed by their electromagnetic de-excitation. Stable -2 charged particles, bound to primordial helium in O-helium (OHe) atoms, represent the simplest model of dark atoms. Here we consider the structure of OHe atomic levels which is a necessary input for the indirect tests of such composite dark matter scenarios, and we give the spectrum of electromagnetic transitions from the levels excited in OHe collisions.

  12. FY14 Progress Report for PL12-LaserSPec SIMS-PD08. Laser Photoionization of Sputtered Neutral atoms in PNNL SIMS and Applications in Nuclear Materials and Environmental Analyses

    Energy Technology Data Exchange (ETDEWEB)

    Willingham, David G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Naes, Benjamin E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fahey, Albert J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Thompson, Sandra E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Cloutier, Janet M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-12-18

    A continuous wave (CW) Ar ion laser producing photons at 244 nm (doubled from the fundamental wavelength at 488nm) was used to ionize neutrals sputtered from representative lanthanide (neodymium oxide, Nd2O3) and actinide (uranium oxide, U3O8) containing materials in the modified Cameca ims-4f at PNNL.

  13. Laser-induced positive ion and neutral atom/molecule emissions from single-crystal CaHPO4 center dot 2H20: The role of electron-beam-induced defects

    Energy Technology Data Exchange (ETDEWEB)

    Dawes, Mary L.(Washington State University); Hess, Wayne P.(BATTELLE (PACIFIC NW LAB)); Kawaguchi, Yuji (VISITORS); Langford, S C.(Washington State University); Dickinson, J. Tom (Washington State University)

    1998-11-01

    We examine laser-induced ion and neutral emissions from single-crystal CaHPO4 center dot 2H2O (brushite), a wide-band-gap, hydrated inorganic single crystal, with 248-nm excimer laser radiation. Both laser-induced ion and neutral emissions are several orders magnitude higher following exposure to 2keV electrons at current densities of 200 uA/cm2 and doses of 1 C/cm2. In addition to intense Ca+ signals, electron-irradiated surfaces yield substantial CaO+, PO+, and P+ signals. As-grown and as-cleaved brushite show only weak neutral O2 and Ca emissions, whereas electron-irradiated surfaces yield enhanced O2, Ca, PO, PO2, and P emissions. Electron irradiation (i) significantly heats the sample, leading to thermal dehydration (CaHPO4 formation) and pyrolysis (Ca2P2O7 formation)and (ii) chemically reduces the surface via electron stimulated desorption. The thermal effects are accompanied by morphological changes, including recrystallization. Although complex, these changes lead to high defect densities, which are responsible for the dramatic enhancements in the observed laser desorption.

  14. Laser-induced positive ion and neutral atom/molecule emission from single-crystal CaHPO4.2H2O: The role of electron-beam-induced defects

    Science.gov (United States)

    Dawes, M. L.; Hess, W.; Kawaguchi, Y.; Langford, S. C.; Dickinson, J. T.

    We examine laser-induced ion and neutral emissions from single-crystal CaHPO4.2H2O (brushite), a wide-band-gap, hydrated inorganic single crystal, with 248-nm excimer laser radiation. Both laser-induced ion and neutral emissions are several orders of magnitude higher following exposure to 2 keV electrons at current densities of 200 μA/cm2 and doses of 1 C/cm2. In addition to intense Ca+ signals, electron-irradiated surfaces yield substantial CaO+, PO+, and P+ signals. As-grown and as-cleaved brushite show only weak neutral O2 and Ca emissions, whereas electron-irradiated surfaces yield enhanced O2, Ca, PO, PO2, and P emissions. Electron irradiation (i) significantly heats the sample, leading to thermal dehydration (CaHPO4 formation) and pyrolysis (Ca2P2O7 formation) and (ii) chemically reduces the surface via electron stimulated desorption. The thermal effects are accompanied by morphological changes, including recrystallization. Although complex, these changes lead to high defect densities, which are responsible for the dramatic enhancements in the observed laser desorption.

  15. Measurements of neutral and ion velocity distribution functions in a Hall thruster

    Science.gov (United States)

    Svarnas, Panagiotis; Romadanov, Iavn; Diallo, Ahmed; Raitses, Yevgeny

    2015-11-01

    Hall thruster is a plasma device for space propulsion. It utilizes a cross-field discharge to generate a partially ionized weakly collisional plasma with magnetized electrons and non-magnetized ions. The ions are accelerated by the electric field to produce the thrust. There is a relatively large number of studies devoted to characterization of accelerated ions, including measurements of ion velocity distribution function using laser-induced fluorescence diagnostic. Interactions of these accelerated ions with neutral atoms in the thruster and the thruster plume is a subject of on-going studies, which require combined monitoring of ion and neutral velocity distributions. Herein, laser-induced fluorescence technique has been employed to study neutral and single-charged ion velocity distribution functions in a 200 W cylindrical Hall thruster operating with xenon propellant. An optical system is installed in the vacuum chamber enabling spatially resolved axial velocity measurements. The fluorescence signals are well separated from the plasma background emission by modulating the laser beam and using lock-in detectors. Measured velocity distribution functions of neutral atoms and ions at different operating parameters of the thruster are reported and analyzed. This work was supported by DOE contract DE-AC02-09CH11466.

  16. Atom-atom entanglement generated at early times by two-photon emission

    Energy Technology Data Exchange (ETDEWEB)

    Leon, Juan; Sabin, Carlos [Instituto de Fisica Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain)], E-mail: leon@imaff.cfmac.csic.es, E-mail: csl@imaff.cfmac.csic.es

    2009-07-15

    We analyze entanglement generation between a pair of neutral two-level atoms that are initially excited in a common electromagnetic vacuum. The nonlocal correlations that appear due to the interaction with the field can become entanglement when the field state is known. We distinguish two different situations: in the first, the field remains in the vacuum state and in the second, two photons are present in the final state. In both cases, we study the dependence of the entanglement on time and interatomic distance, at ranges related with locality issues.

  17. Research on Stress Neutral Layer Offset in the Straightening Process

    Directory of Open Access Journals (Sweden)

    Hailian Gui

    2015-01-01

    Full Text Available The stress neutral layer offset is analyzed by theoretical and numerical calculation methods. In traditional straightening theory, the stress neutral layer was consistent with the geometric central layer. However, there is a phenomenon that the stress neutral layer has some offset with the geometric neutral layer. This offset is a very important factor for improving the precision of the straightening force. The formula of the stress neutral layer offset is obtained by a theoretical method and the change law is given by numerical calculation method. The neutral layer offset theory provides the theoretical basis for establishing the model of straightening force precisely.

  18. Estimation Using an Enhancement Factor on Non Local Thermodynamic Equilibrium Behavior of High-lying Energy Levels of Neutral Atom in Argon Radio-Frequency Inductively-Coupled Plasma.

    Science.gov (United States)

    Wagatsuma, Kazuaki; Satoh, Kozue

    2016-01-01

    This paper describes a plasma-diagnostic method using an enhancement factor on the Boltzmann distribution among emission lines of iron atom in an argon radio-frequency inductively-coupled plasma (ICP). It indicated that Boltzmann plots of the atomic lines having lower excitation energies (3.4 to 4.8 eV) were well fitted on a straight line while those having more than 5.5 eV deviated upwards from a linear relationship. This observation could be explained by the fact that ICP is not in a complete thermodynamic equilibrium between direct excitation to energy levels of iron atom, ionization of iron atom, and radiative decay processes to the ground state. Especially, the recombination of iron ion with captured electron should accompany cascade de-excitations between closely-spaced excited levels just below the ionization limit, the rates of which become slower as a whole; as a result, these high-lying levels might be more populated than the low-lying levels as if a different LTE condition coexists on the high energy side. This overpopulation could be quantitatively estimated using an enhancement factor (EF), which was a ratio of the observed intensity to the expected value extrapolated from the normal distribution on the low energy side. The EFs were generally small (less than 3); therefore, the cascade de-excitation process would slightly contribute to the population of these excited levels. It could be considered from variations of the EF that the overpopulation proceeded to a larger extent at lower radio-frequency forward powers, at higher flow rates of the carrier gas, or at higher observation heights. The reason for this is that the kinetic energy of energetic particles, such as electrons, becomes reduced under all of these plasma conditions, thus enabling the high-lying levels to be more populated by cascade de-excitation processes from iron ion rather than by collisional excitation processes with the energetic particles. A similar Boltzmann analysis using the EF

  19. 西班牙法西斯政权的建立及在二战中保持中立的原因%Analyzing on the Establishment of the Spain Fascist Regime and the Reason for It Being Neutral During World War II

    Institute of Scientific and Technical Information of China (English)

    陈长风

    2013-01-01

      Spain established the fascist dictatorship between World War I and World War II . However , Spain as one of the fascist states maintained neutrality in the war involved with two -thirds countries world-wide w hile Germany ,Italy and Japan allied as Axis and committed monstrous crimes as defeated nations in the unprecedented war in human history .It has been a tricky question baffling many historians and schol-ars of international relations for years . This paper briefly illustrates the facts ,results and influences of Spanish civil war .On that basis ,the paper analyzes the causes and effects of Spanish civil war and the rea-sons w hy Franco fascist regime remained neutrality during the World War II .%  西班牙在一战后二战前建立起了法西斯独裁统治的国家。德、意、日三国结为轴心国在二战中犯下了滔天罪行,然而同为法西斯国家的西班牙却在这场全球三分之二的国家被卷入的世界大战中保持中立,让史学界和国际关系学界诸多学者难以理解。阐述了西班牙内战的经过、结局和影响,在此基础上,探析了西班牙内战的前因后果与佛朗哥法西斯政权在二战中保持中立的原因。

  20. Chemical reaction dynamics of Rydberg atoms with neutral molecules: a comparison of molecular-beam and classical trajectory results for the H(n)+D2-->HD+D(n') reaction.

    Science.gov (United States)

    Song, Hui; Dai, Dongxu; Wu, Guorong; Wang, Chia Chen; Harich, Steven A; Hayes, Michael Y; Wang, Xiuyan; Gerlich, Dieter; Yang, Xueming; Skodje, Rex T

    2005-08-15

    Recent molecular-beam experiments have probed the dynamics of the Rydberg-atom reaction, H(n)+D2-->HD+D(n) at low collision energies. It was discovered that the rotationally resolved product distribution was remarkably similar to a much more limited data set obtained at a single scattering angle for the ion-molecule reaction H++D2-->D++HD. The equivalence of these two problems would be consistent with the Fermi-independent-collider model (electron acting as a spectator) and would provide an important new avenue for the study of ion-molecule reactions. In this work, we employ a classical trajectory calculation on the ion-molecule reaction to facilitate a more extensive comparison between the two systems. The trajectory simulations tend to confirm the equivalence of the ion+molecule dynamics to that for the Rydberg-atom+molecule system. The theory reproduces the close relationship of the two experimental observations made previously. However, some differences between the Rydberg-atom experiments and the trajectory simulations are seen when comparisons are made to a broader data set. In particular, the angular distribution of the differential cross section exhibits more asymmetry in the experiment than in the theory. The potential breakdown of the classical model is discussed. The role of the "spectator" Rydberg electron is addressed and several crucial issues for future theoretical work are brought out.

  1. Neutralization of English Consonants

    Institute of Scientific and Technical Information of China (English)

    庞彬彬

    2011-01-01

    This paper gives a brief account of English consonant cluster's structure and phonetic features from the perspective of the definition and cause of neutralization of English consonants as well as their distinctive features and oppositions.It comes up with the final conclusion that neutralization exists in only thirteen English consonant clusters,among a large number of consonant clusters.

  2. Universal bosonic tetramers of dimer-atom-atom structure

    OpenAIRE

    Deltuva, A.

    2012-01-01

    Unstable four-boson states having an approximate dimer-atom-atom structure are studied using momentum-space integral equations for the four-particle transition operators. For a given Efimov trimer the universal properties of the lowest associated tetramer are determined. The impact of this tetramer on the atom-trimer and dimer-dimer collisions is analyzed. The reliability of the three-body dimer-atom-atom model is studied.

  3. Scattering resonances of ultracold atoms in confined geometries

    Energy Technology Data Exchange (ETDEWEB)

    Saeidian, Shahpoor

    2008-06-18

    Subject of this thesis is the investigation of the quantum dynamics of ultracold atoms in confined geometries. We discuss the behavior of ground state atoms inside a 3D magnetic quadrupole field. Such atoms in enough weak magnetic fields can be approximately treated as neutral point-like particles. Complementary to the well-known positive energy resonances, we point out the existence of short-lived negative energy resonances. The latter originate from a fundamental symmetry of the underlying Hamiltonian. We drive a mapping of the two branches of the spectrum. Moreover, we analyze atomic hyperfine resonances in a magnetic quadrupole field. This corresponds to the case for which both the hyperfine and Zeeman interaction, are comparable, and should be taken into account. Finally, we develop a general grid method for multichannel scattering of two atoms in a two-dimensional harmonic confinement. With our approach we analyze transverse excitations/deexcitations in the course of the collisional process (distinguishable or identical atoms) including all important partial waves and their couplings due to the broken spherical symmetry. Special attention is paid to suggest a non-trivial extension of the CIRs theory developed so far only for the single-mode regime and zero-energy limit. (orig.)

  4. Net Neutrality: Media Discourses and Public Perception

    Directory of Open Access Journals (Sweden)

    Christine Quail

    2010-01-01

    Full Text Available This paper analyzes media and public discourses surrounding net neutrality, with particular attention to public utility philosophy, from a critical perspective. The article suggests that further public education about net neutrality would be beneficial. The first portion of this paper provides a survey of the existing literature surrounding net neutrality, highlighting the contentious debate between market-based and public interest perspectives. In order to contextualize the debate, an overview of public utility philosophy is provided, shedding light on how the Internet can be conceptualized as a public good. Following this discussion, an analysis of mainstream media is presented, exploring how the media represents the issue of net neutrality and whether or not the Internet is discussed through the lens of public utility. To further examine how the net neutrality debate is being addressed, and to see the potential impacts of media discourses on the general public, the results of a focus group are reported and analyzed. Finally, a discussion assesses the implications of the net neutrality debate as presented through media discourses, highlighting the future of net neutrality as an important policy issue.

  5. Trapped Atoms in One-Dimensional Photonic Crystals

    Science.gov (United States)

    Kimble, H.

    2013-05-01

    I describe one-dimensional photonic crystals that support a guided mode suitable for atom trapping within a unit cell, as well as a second probe mode with strong atom-photon interactions. A new hybrid trap is analyzed that combines optical and Casimir-Polder forces to form stable traps for neutral atoms in dielectric nanostructures. By suitable design of the band structure, the atomic spontaneous emission rate into the probe mode can exceed the rate into all other modes by more than tenfold. The unprecedented single-atom reflectivity r0 ~= 0 . 9 for the guided probe field could create new scientific opportunities, including quantum many-body physics for 1 D atom chains with photon-mediated interactions and high-precision studies of vacuum forces. Towards these goals, my colleagues and I are pursuing numerical simulation, device fabrication, and cold-atom experiments with nanoscopic structures. Funding is provided by by the IQIM, an NSF PFC with support of the Moore Foundation, by the AFOSR QuMPASS MURI, by the DoD NSSEFF program (HJK), and by NSF Grant PHY0652914 (HJK). DEC acknowledges funding from Fundacio Privada Cellex Barcelona.

  6. Fast metastable hydrogen atoms from H2 molecules: twin atoms

    Directory of Open Access Journals (Sweden)

    Trimèche A.

    2015-01-01

    Full Text Available It is a difficult task to obtain “twin atoms”, i.e. pairs of massive particles such that one can perform experiments in the same fashion that is routinely done with “twin photons”. One possible route to obtain such pairs is by dissociating homonuclear diatomic molecules. We address this possibility by investigating the production of metastable H(2s atoms coming from the dissociation of cold H2 molecules produced in a Campargue nozzle beam crossing an electron beam from a high intensity pulsed electron gun. Dissociation by electron impact was chosen to avoid limitations of target molecular excited states due to selection rules. Detectors placed several centimeters away from the collision center, and aligned with respect to possible common molecular dissociation channel, analyze the neutral fragments as a function of their time-of-flight (TOF through Lyman-α detection. Evidence for the first time observed coincidence of pairs of H(2s atoms obtained this way is presented.

  7. Neutral thermospheric temperature from ion concentration measurements

    Science.gov (United States)

    Breig, E. L.; Donaldson, J. S.; Hanson, W. B.; Hoffman, J. H.; Power, R. A.; Kayser, D. C.; Spencer, N. W.; Wharton, L. E.

    1981-01-01

    A technique for extracting information on neutral temperature from in situ F region measurements of O(+) and H(+) ion concentrations is analyzed and evaluated. Advantage is taken of the condition of charge-exchange equilibrium of these species in the neighborhood of 320 km to infer the associated relative abundances of neutral oxygen and hydrogen. Results are shown to be generally consistent with other concurrent in situ measurements.

  8. Energy Conservation Tests of a Coupled Kinetic-kinetic Plasma-neutral Transport Code

    Energy Technology Data Exchange (ETDEWEB)

    Stotler, D. P.; Chang, C. S.; Ku, S. H.; Lang, J.; Park, G.

    2012-08-29

    A Monte Carlo neutral transport routine, based on DEGAS2, has been coupled to the guiding center ion-electron-neutral neoclassical PIC code XGC0 to provide a realistic treatment of neutral atoms and molecules in the tokamak edge plasma. The DEGAS2 routine allows detailed atomic physics and plasma-material interaction processes to be incorporated into these simulations. The spatial pro le of the neutral particle source used in the DEGAS2 routine is determined from the uxes of XGC0 ions to the material surfaces. The kinetic-kinetic plasma-neutral transport capability is demonstrated with example pedestal fueling simulations.

  9. Modeling of neutrals in the Linac4 H{sup −} ion source plasma: Hydrogen atom production density profile and H{sub α} intensity by collisional radiative model

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, T., E-mail: t.yamamoto@ppl.appi.keio.ac.jp; Shibata, T.; Ohta, M.; Yasumoto, M.; Nishida, K.; Hatayama, A. [Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522 (Japan); Mattei, S.; Lettry, J. [CERN, 1211 Geneva 23 (Switzerland); Sawada, K. [Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan); Fantz, U. [Max-Plank-Instutut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany)

    2014-02-15

    To control the H{sup 0} atom production profile in the H{sup −} ion sources is one of the important issues for the efficient and uniform surface H{sup −} production. The purpose of this study is to construct a collisional radiative (CR) model to calculate the effective production rate of H{sup 0} atoms from H{sub 2} molecules in the model geometry of the radio-frequency (RF) H{sup −} ion source for Linac4 accelerator. In order to validate the CR model by comparison with the experimental results from the optical emission spectroscopy, it is also necessary for the model to calculate Balmer photon emission rate in the source. As a basic test of the model, the time evolutions of H{sup 0} production and the Balmer H{sub α} photon emission rate are calculated for given electron energy distribution functions in the Linac4 RF H{sup −} ion source. Reasonable test results are obtained and basis for the detailed comparisons with experimental results have been established.

  10. Edge rotation from momentum transport by neutrals

    Science.gov (United States)

    Omotani, JT; Newton, SL; Pusztai, I.; Fülöp, T.

    2016-11-01

    Due to their high cross field mobility, neutral atoms can have a strong effect on transport even at the low relative densities found inside the separatrix. We use a charge-exchange dominated model for the neutrals, coupled to neoclassical ions, to calculate momentum transport when it is dominated by the neutrals. We can then calculate self-consistently the radial electric field and predict the intrinsic rotation in an otherwise torque-free plasma. Using a numerical solver for the ion distribution to allow arbitrary collisionality, we investigate the effects of inverse aspect ratio and elongation on plasma rotation. We also calculate the rotation of a trace carbon impurity, to facilitate future comparison to experiments using charge exchange recombination spectroscopy diagnostics.

  11. Estimating the stoichiometry of HIV neutralization.

    Science.gov (United States)

    Magnus, Carsten; Regoes, Roland R

    2010-03-19

    HIV-1 virions infect target cells by first establishing contact between envelope glycoprotein trimers on the virion's surface and CD4 receptors on a target cell, recruiting co-receptors, fusing with the cell membrane and finally releasing the genetic material into the target cell. Specific experimental setups allow the study of the number of trimer-receptor-interactions needed for infection, i.e., the stoichiometry of entry and also the number of antibodies needed to prevent one trimer from engaging successfully in the entry process, i.e., the stoichiometry of (trimer) neutralization. Mathematical models are required to infer the stoichiometric parameters from these experimental data. Recently, we developed mathematical models for the estimations of the stoichiometry of entry [1]. In this article, we show how our models can be extended to investigate the stoichiometry of trimer neutralization. We study how various biological parameters affect the estimate of the stoichiometry of neutralization. We find that the distribution of trimer numbers-which is also an important determinant of the stoichiometry of entry-influences the estimated value of the stoichiometry of neutralization. In contrast, other parameters, which characterize the experimental system, diminish the information we can extract from the data about the stoichiometry of neutralization, and thus reduce our confidence in the estimate. We illustrate the use of our models by re-analyzing previously published data on the neutralization sensitivity [2], which contains measurements of neutralization sensitivity of viruses with different envelope proteins to antibodies with various specificities. Our mathematical framework represents the formal basis for the estimation of the stoichiometry of neutralization. Together with the stoichiometry of entry, the stoichiometry of trimer neutralization will allow one to calculate how many antibodies are required to neutralize a virion or even an entire population of

  12. A neutralization-reionization and reactivity mass spectrometry study of the generation of neutral hydroxymethylene.

    Science.gov (United States)

    Lin, Yawei; Crestoni, Maria Elisa; Fornarini, Simonetta; Mayer, Paul M

    2011-06-01

    Neutral hydroxymethylene HCOH is an important intermediate in several chemical reactions; however, it is difficult to observe due to its high reactivity. In this work, neutral hydroxymethylene and formaldehyde were generated by charge exchange neutralization of their respective ionic counterparts and then were reionized and detected as positive-ion recovery signals in neutralization-reionization mass spectrometry in a magnetic sector instrument of BEE geometry. The reionized species were characterized by their subsequent collision-induced dissociation mass spectra. The transient hydroxymethylene neutral was observed to isomerize to formaldehyde with an experimental time span exceeding 13.9 µs. The vertical neutralization energy of the HCOH(+•) ion has also been assayed using charge transfer reactions between the fast ions and stationary target gases of differing ionization energy. The measured values match the result of ab initio calculations at the QCISD/6-311 + G(d,p) and CCSD(T)/6-311 + + G(3df,2p) levels of theory. Neutral hydroxymethylene was also produced by proton transfer from CH(2) OH(+) to a strong base such as pyridine, confirmed by appropriate isotopic labeling. There is a kinetic isotope effect (KIE) for H(+) versus D(+) transfer from the C atom of the hydroxymethyl cation of ∼3, consistent with a primary KIE of a nearly thermoneutral reaction.

  13. Detection of the level of fluoride in the commercially available toothpaste using laser induced breakdown spectroscopy with the marker atomic transition line of neutral fluorine at 731.1 nm

    Science.gov (United States)

    Gondal, M. A.; Maganda, Y. W.; Dastageer, M. A.; Al Adel, F. F.; Naqvi, A. A.; Qahtan, T. F.

    2014-04-01

    Fourth harmonic of a pulsed Nd:YAG laser (wavelength 266 nm) in combination with high resolution spectrograph equipped with Gated ICCD camera has been employed to design a high sensitive analytical system. This detection system is based on Laser Induced Breakdown Spectroscopy and has been tested first time for analysis of semi-fluid samples to detect fluoride content present in the commercially available toothpaste samples. The experimental parameters were optimized to achieve an optically thin and in local thermo dynamic equilibrium plasma. This improved the limits of detection of fluoride present in tooth paste samples. The strong atomic transition line of fluorine at 731.102 nm was used as the marker line to quantify the fluoride concentration levels. Our LIBS system was able to detect fluoride concentration levels in the range of 1300-1750 ppm with a detection limit of 156 ppm.

  14. BEAMS3D Neutral Beam Injection Model

    Science.gov (United States)

    McMillan, Matthew; Lazerson, Samuel A.

    2014-09-01

    With the advent of applied 3D fields in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous slowing down, and pitch angle scattering are modeled with the ADAS atomic physics database. Elementary benchmark calculations are presented to verify the collisionless particle orbits, NBI model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields. Notice: this manuscript has been authored by Princeton University under Contract Number DE-AC02-09CH11466 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

  15. Analyzing the effect of the forces exerted on cantilever probe tip of atomic force microscope with tapering-shaped geometry and double piezoelectric extended layers in the air and liquid environments

    Science.gov (United States)

    Korayem, Moharam Habibnejad; Nahavandi, Amir

    2017-01-01

    The aim of the present study is to assess the force vibrational performance of tapering-shaped cantilevers, using Euler-Bernoulli theory. Tapering-shaped cantilevers have plan-view geometry consisting of a rectangular section at the clamped end and a triangular section at the tip. Hamilton's principle is utilized to obtain the partial differential equations governing the nonlinear vibration of the system as well as the corresponding boundary conditions. In this model, a micro cantilever, which is covered by two piezoelectric layers at the top and the bottom, is modeled at angle α. Both of these layers are subjected to similar AC and DC voltages. This paper attempts to determine the effect of the capillary force exerted on the cantilever probe tip of an atomic force microscope. The capillary force emerges due to the contact between thin water films with a thickness of hc which have accumulated on the sample and the probe. In addition, an attempt is made to develop the capillary force between the tip and the sample surface with respect to the geometry obtained. The smoothness or the roughness of the surfaces as well as the geometry of the cantilever tip have significant effects on the modeling of forces applied to the probe tip. In this article, the Van der Waals and the repulsive forces are considered to be the same in all of the simulations, and only is the capillary force altered in order to evaluate the role of this force in the atomic force microscope based modeling. We also indicate that the tip shape and the radial distance of the meniscus greatly influence the capillary force. The other objective of our study is to draw a comparison between tapering-and rectangular-shaped cantilevers. Furthermore, the equation for converting the tip of a tapering-shaped cantilever into a rectangular cantilever is provided. Moreover, the modal analysis method is employed to solve the motion equation. The mode shape function for the two tapering-shaped sections of the first

  16. Neutral Resonant Ionization in Hydrogen Anion Production

    Science.gov (United States)

    Vogel, John

    2013-09-01

    Dissociative ionization of molecules causes gas phase H- but fails to explain anion intensity. Atomic collisions on surfaces with reduced work function give anions, but also fail to explain intensity, lowered electron density, and diagnostics. Neutral resonant ionization of H(2s) atoms to ion pairs is here predicted with a very high cross section. H(2s,p) atoms are resonant with numerous short-lived excited states (``resonances'') of H- as well as the putative doubly-excited stable state of H- which resists production by other means. This state decays through 1Σu+ (2s σu2) to a singly excited ion pair, leaving both proton and anion with 3.8 eV energy. H(2s,p) atoms arise from dissociative recombination of trihydrogen ion (H3+)which dominates ion content of hydrogen plasmas. Initial H(2s,p) are resonantly produced by ground state Cs atoms or excited Ar, Kr, and Xe atoms, but these initiators are not needed to sustain anion production. This theory may explain the intense ion source at Cal Tech that produced 1.5 mA/cm2 H3 in the mid-1980's (1). A full CRM calculation is not complete, but equilibrium calculations suggest that >1 mA/cm2 H- may be predicted.

  17. Neutral particle lithography

    Science.gov (United States)

    Craver, Barry Paul

    Neutral particle lithography (NPL) is a high resolution, proximity exposure technique where a broad beam of energetic neutral particles floods a stencil mask and transmitted beamlets transfer the mask pattern to resist on a substrate, such that each feature is printed in parallel, rather than in the serial manner of electron beam lithography. It preserves the advantages of ion beam lithography (IBL), including extremely large depth-of-field, sub-5 nm resist scattering, and the near absence of diffraction, yet is intrinsically immune to charge-related artifacts including line-edge roughness and pattern placement errors due to charge accumulation on the mask and substrate. In our experiments, a neutral particle beam is formed by passing an ion beam (e.g., 30 keV He+) through a high pressure helium gas cell (e.g., 100 mTorr) to convert the ions to energetic neutrals through charge transfer scattering. The resolution of NPL is generally superior to that of IBL for applications involving insulating substrates, large proximity gaps, and ultra-small features. High accuracy stepped exposures with energetic neutral particles, where magnetic or electrostatic deflection is impossible, have been obtained by clamping the mask to the wafer, setting the proximity gap with a suitable spacer, and mechanically inclining the mask/wafer stack relative to the beam. This approach is remarkably insensitive to vibration and thermal drift; nanometer scale image offsets have been obtained with +/-2 nm placement accuracy for experiments lasting over one hour. Using this nanostepping technique, linewidth versus dose curves were obtained, from which the NPL lithographic blur was determined as 4.4+/-1.4 nm (1sigma), which is 2-3 times smaller than the blur of electron beam lithography. Neutral particle lithography has the potential to form high density, periodic patterns with sub-10 nm resolution.

  18. Atomic energy

    CERN Multimedia

    1996-01-01

    Interviews following the 1991 co-operation Agreement between the Department of Atomic Energy (DAE) of the Government of India and the European Organization for Nuclear Research (CERN) concerning the participation in the Large Hadron Collider Project (LHC) . With Chidambaram, R, Chairman, Atomic Energy Commission and Secretary, Department of Atomic Energy, Department of Atomic Energy (DAE) of the Government of India and Professor Llewellyn-Smith, Christopher H, Director-General, CERN.

  19. Atom chips

    CERN Document Server

    Reichel, Jakob

    2010-01-01

    This book provides a stimulating and multifaceted picture of a rapidly developing field. The first part reviews fundamentals of atom chip research in tutorial style, while subsequent parts focus on the topics of atom-surface interaction, coherence on atom chips, and possible future directions of atom chip research. The articles are written by leading researchers in the field in their characteristic and individual styles.

  20. Plasma-Neutral Coupling on the Dark and Bright Sides of Antarctica

    Science.gov (United States)

    Chu, X.; Yu, Z.; Fong, W.; Chen, C.; Zhao, J.; Huang, W.; Roberts, B. R.; Fuller-Rowell, T. J.; Richmond, A. D.; Gerrard, A. J.; Weatherwax, A. T.; Gardner, C. S.

    2014-12-01

    The polar mesosphere and thermosphere provide a unique natural laboratory for studying the complex physical, chemical, neutral dynamical and electrodynamics processes in the Earth's atmosphere and space environment. McMurdo (geographic 77.83S, geomagnetic 80S) is located by the poleward edge of the aurora oval; so energetic particles may penetrate into the lower thermosphere and mesosphere along nearly vertical geomagnetic field lines. Lidar observations at McMurdo from December 2010 to 2014 have discovered several neutral atmosphere phenomena closely related to ionosphereic parameters and geomagnetic activity. For example, the diurnal tidal amplitude of temperatures not only increases super-exponentially from 100 to 110 km but also its growth rate becomes larger at larger Kp index. The lidar discovery of neutral iron (Fe) layers with gravity wave signatures in the thermosphere enabled the direct measurements of neutral temperatures from 30 to 170 km, revealing the neutral-ion coupling and aurora-enhanced Joule heating. A lidar 'marathon' of 174-hour continuous observations showed dramatic changes of composition (Fe atoms and ice particles) densities (over 40 times) in the mesopause region and their correlations to solar events. In this paper we will study the plasma-neutral coupling on the dark side of Antarctica via observation analysis and numerical modeling of the thermospheric Fe layers in the 100-200 km. A newly developed thermospheric Fe/Fe+ model is used to quantify how Fe+ ions are transported from their main deposition region to the E-F region and then neutralized to form Fe layers under dark polar conditions. We will also study the plasma-neutral coupling on the bright side of Antarctica via analyzing Fe events in summer. Complementary observations will be combined to show how the extreme changes of Fe layers are related to aurora particle precipitation and visible/sub-visible ice particles. These observations and studies will open new areas of

  1. Bleach Neutralizes Mold Allergens

    Science.gov (United States)

    Science Teacher, 2005

    2005-01-01

    Researchers at National Jewish Medical and Research Center have demonstrated that dilute bleach not only kills common household mold, but may also neutralize the mold allergens that cause most mold-related health complaints. The study, published in the Journal of Allergy and Clinical Immunology, is the first to test the effect on allergic…

  2. CO2-Neutral Fuels

    NARCIS (Netherlands)

    Goede, A.; van de Sanden, M. C. M.

    2016-01-01

    Mimicking the biogeochemical cycle of System Earth, synthetic hydrocarbon fuels are produced from recycled CO2 and H2O powered by renewable energy. Recapturing CO2 after use closes the carbon cycle, rendering the fuel cycle CO2 neutral. Non-equilibrium molecular CO2 vibrations are key to high energy

  3. CO2-Neutral Fuels

    Science.gov (United States)

    Goede, Adelbert; van de Sanden, Richard

    2016-06-01

    Mimicking the biogeochemical cycle of System Earth, synthetic hydrocarbon fuels are produced from recycled CO2 and H2O powered by renewable energy. Recapturing CO2 after use closes the carbon cycle, rendering the fuel cycle CO2 neutral. Non-equilibrium molecular CO2 vibrations are key to high energy efficiency.

  4. CO2-Neutral Fuels

    NARCIS (Netherlands)

    Goede, A.; van de Sanden, M. C. M.

    2016-01-01

    Mimicking the biogeochemical cycle of System Earth, synthetic hydrocarbon fuels are produced from recycled CO2 and H2O powered by renewable energy. Recapturing CO2 after use closes the carbon cycle, rendering the fuel cycle CO2 neutral. Non-equilibrium molecular CO2 vibrations are key to high energy

  5. Variational electrodynamics of Atoms

    CERN Document Server

    De Luca, Jayme

    2013-01-01

    We study extrema with velocity discontinuities for the variational electromagnetic two-body problem. Along $C^2$ segments, these broken extrema satisfy the Euler-Lagrange equations of the variational principle, which are neutral differential delay equations with state-dependent deviating arguments. At points where accelerations are not defined and velocities are discontinuous, broken extrema satisfy Weierstrass-Erdmann corner conditions that energies and momenta are continuous. Here we construct periodic broken extrema near the $C^{\\infty}$ two-body circular orbits, using piecewise-defined $C^2$ solutions of the neutral differential delay equations along regular segments and a variational approximation for the boundary-layer segments. Broken periodic extrema with an integer number of corner points bifurcate from a discrete set of circular orbits, with scales defined by the Weierstrass-Erdmann corner conditions. We consider the three cases of hydrogen, muonium and positronium atoms. In each case the broken ext...

  6. Structures and energetics of neutral and ionic silicon-germanium clusters: density functional theory and coupled cluster studies.

    Science.gov (United States)

    Wang, Yi-Siang; Chao, Sheng D

    2011-03-10

    We have calculated the structural and energetic properties of neutral and ionic (singly charged anionic and cationic) semiconductor binary silicon-germanium clusters Si(m)Ge(n) for s = m + n ≤ 12 using the density functional theory (DFT-B3LYP) and coupled cluster [CCSD(T)] methods with Pople's 6-311++G(3df, 3pd) basis set. Neutral and anionic clusters share similar ground state structures for s = 3-7, independent of the stoichiometry and atom locations, but start to deviate at s = 8. The relative energetic stability of the calculated ground state structures among possible isomers has been analyzed through a bond strength propensity model where the pair interactions of Si-Si, Si-Ge, and Ge-Ge are competing. Electron affinities, ionization potentials, energy gaps between the highest and lowest occupied molecular orbitals (HOMO-LUMO gaps), and cluster mixing energies were calculated and analyzed. Overall, for a fixed s, the vertical ionization potential increases as the number of silicon atoms m increases, while the vertical electron affinity shows a dip at m = 2. As s increases, the ionization potentials increase from s = 2 to s = 3 and then decrease slowly to s = 8. The mixing energies for neutral and ionic clusters are all negative, indicating that the binary clusters are more stable than pure elemental clusters. Except for s = 4 and 8, cationic clusters are more stable than anionic ones and, thus, are more likely to be observed in experiments.

  7. Atomic polarizabilities

    Energy Technology Data Exchange (ETDEWEB)

    Safronova, M. S. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Clark, Charles W. [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899-8410 (United States); Kozlov, M. G. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation)

    2015-01-22

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.

  8. A magnetic guide for cold atoms

    CERN Document Server

    Richmond, J A; Cantwell, B P; Opat, G I

    1998-01-01

    We propose a novel method for guiding cold, neutral atoms using static magnetic fields. A theoretical study of the magnetic field produced by a tube consisting of two identical, interwound solenoids carrying equal but opposite currents is presented. This field is almost zero throughout the centre of the tube, but it increases with exponential rapidity as one approaches the walls formed by the current carrying wires. Hence, cold atoms passing through the tube may be reflected by magnetic mirror effects near the walls. Applying this technique to a free-falling cloud of magneto-optically cooled caesium atoms we hope to construct atomic guides to facilitate the manipulation of cold atomic beams.

  9. Optical lattice on an atom chip

    DEFF Research Database (Denmark)

    Gallego, D.; Hofferberth, S.; Schumm, Thorsten

    2009-01-01

    Optical dipole traps and atom chips are two very powerful tools for the quantum manipulation of neutral atoms. We demonstrate that both methods can be combined by creating an optical lattice potential on an atom chip. A red-detuned laser beam is retroreflected using the atom chip surface as a high......-quality mirror, generating a vertical array of purely optical oblate traps. We transfer thermal atoms from the chip into the lattice and observe cooling into the two-dimensional regime. Using a chip-generated Bose-Einstein condensate, we demonstrate coherent Bloch oscillations in the lattice....

  10. Ultracold atoms on atom chips

    DEFF Research Database (Denmark)

    Krüger, Peter; Hofferberth, S.; Haller, E.

    2005-01-01

    Miniaturized potentials near the surface of atom chips can be used as flexible and versatile tools for the manipulation of ultracold atoms on a microscale. The full scope of possibilities is only accessible if atom-surface distances can be reduced to microns. We discuss experiments in this regime...

  11. An atom-by-atom assembler of defect-free arbitrary 2d atomic arrays

    CERN Document Server

    Barredo, Daniel; Lienhard, Vincent; Lahaye, Thierry; Browaeys, Antoine

    2016-01-01

    Large arrays of individually controlled atoms trapped in optical tweezers are a very promising platform for quantum engineering applications. However, to date, only disordered arrays have been demonstrated, due to the non-deterministic loading of the traps. Here, we demonstrate the preparation of fully loaded, two-dimensional arrays of up to 50 microtraps each containing a single atom, and arranged in arbitrary geometries. Starting from initially larger, half-filled matrices of randomly loaded traps, we obtain user-defined target arrays at unit filling. This is achieved with a real-time control system and a moving optical tweezers that performs a sequence of rapid atom moves depending on the initial distribution of the atoms in the arrays. These results open exciting prospects for quantum engineering with neutral atoms in tunable geometries.

  12. An atom-by-atom assembler of defect-free arbitrary two-dimensional atomic arrays

    Science.gov (United States)

    Barredo, Daniel; de Léséleuc, Sylvain; Lienhard, Vincent; Lahaye, Thierry; Browaeys, Antoine

    2016-11-01

    Large arrays of individually controlled atoms trapped in optical tweezers are a very promising platform for quantum engineering applications. However, deterministic loading of the traps is experimentally challenging. We demonstrate the preparation of fully loaded two-dimensional arrays of up to ~50 microtraps, each containing a single atom and arranged in arbitrary geometries. Starting from initially larger, half-filled matrices of randomly loaded traps, we obtain user-defined target arrays at unit filling. This is achieved with a real-time control system and a moving optical tweezers, which together enable a sequence of rapid atom moves depending on the initial distribution of the atoms in the arrays. These results open exciting prospects for quantum engineering with neutral atoms in tunable two-dimensional geometries.

  13. Conduction channels at finite bias in single-atom gold contacts

    DEFF Research Database (Denmark)

    Brandbyge, Mads; Kobayashi, Nobuhiko; Tsukada, Masaru

    1999-01-01

    We consider the effect of a finite voltage bias on the conductance of single-atom gold contacts. We employ a nonorthogonal spn-tight-binding Hamiltonian combined with a local charge neutrality assumption. The conductance and charge distributions for finite bias are calculated using the nonequilib......We consider the effect of a finite voltage bias on the conductance of single-atom gold contacts. We employ a nonorthogonal spn-tight-binding Hamiltonian combined with a local charge neutrality assumption. The conductance and charge distributions for finite bias are calculated using...... the nonequilibrium-Green-function formalism. We calculate the voltage drop through the contacts and find the main drop located near the negative electrode. We argue that this is due to the filled d-state resonances. The conduction is analyzed in terms of transmission eigenchannels and density of states...

  14. Between detection and neutralization.

    Energy Technology Data Exchange (ETDEWEB)

    Snell, Mark Kamerer; Green, Mary Wilson; Adams, Douglas Glenn; Pritchard, Daniel Allison

    2005-08-01

    Security system analytical performance analysis is generally based on the probability of system effectiveness. The probability of effectiveness is a function of the probabilities of interruption and neutralization. Interruption occurs if the response forces are notified in sufficient time to engage the adversary. Neutralization occurs if the adversary attack is defeated after the security forces have actively engaged the adversary. Both depend upon communications of data. This paper explores details of embedded communications functions that are often assumed to be inconsequential. It is the intent of the authors to bring focus to an issue in security system modeling that, if not well understood, has the potential to be a deciding factor in the overall system failure or effectiveness.

  15. Gargamelle: neutral current event

    CERN Multimedia

    1973-01-01

    This event shows real tracks of particles from the 1200 litre Gargamelle bubble chamber that ran on the PS from 1970 to 1976 and on the SPS from 1976 to 1979. In this image a neutrino passes close to a nucleon and reemerges as a neutrino. Such events are called neutral curent, as they are mediated by the Z0 boson which has no electric charge.

  16. Optical atomic clocks

    CERN Document Server

    Poli, N; Gill, P; Tino, G M

    2014-01-01

    In the last ten years extraordinary results in time and frequency metrology have been demonstrated. Frequency-stabilization techniques for continuous-wave lasers and femto-second optical frequency combs have enabled a rapid development of frequency standards based on optical transitions in ultra-cold neutral atoms and trapped ions. As a result, today's best performing atomic clocks tick at an optical rate and allow scientists to perform high-resolution measurements with a precision approaching a few parts in $10^{18}$. This paper reviews the history and the state of the art in optical-clock research and addresses the implementation of optical clocks in a possible future redefinition of the SI second as well as in tests of fundamental physics.

  17. Laser-Free Cold-Atom Gymnastics

    Science.gov (United States)

    Gould, Harvey; Feinberg, Benedict; Munger, Charles T., Jr.; Nishimura, Hiroshi

    2017-01-01

    We have performed beam transport simulations on ultra cold (2 μK) and cold (130 μK) neutral Cs atoms in the F = M = + 4 (magnetic weak-field seeking) ground state. We use inhomogeneous magnetic fields to focus and accelerate the atoms. Acceleration of neutral atoms by an inhomogeneous magnetic field was demonstrated by Stern and Gerlach in 1922. In the simulations, a two mm diameter cloud of atoms is released to fall under gravity. A magnetic coil focuses the falling atoms. After falling 41 cm, the atoms are reflected in the magnetic fringe field of a solenoid. They return to their starting height, about 0.7 s later, having passed a second time through the focusing coil. The simulations show that > 98 % of ultra cold Cs atoms and > 70 % of cold Cs atoms will survive at least 15 round trips (assuming perfect vacuum). More than 100 simulations were run to optimize coil currents and focusing coil diameter and height. Simulations also show that atoms can be launched into a fountain. An experimental apparatus to test the simulations, is being constructed. This technique may find application in atomic fountain clocks, interferometers, and gravitometers, and may be adaptable for use in microgravity. It may also work with Bose-Einstein condensates of paramagnetic atoms.

  18. Cold atoms close to surfaces

    DEFF Research Database (Denmark)

    Krüger, Peter; Wildermuth, Stephan; Hofferberth, Sebastian

    2005-01-01

    Microscopic atom optical devices integrated on atom chips allow to precisely control and manipulate ultra-cold (T atoms and Bose-Einstein condensates (BECs) close to surfaces. The relevant energy scale of a BEC is extremely small (down to ... be utilized as a sensor for variations of the potential energy of the atoms close to the surface. Here we describe how to use trapped atoms as a measurement device and analyze the performance and flexibility of the field sensor. We demonstrate microscopic magnetic imaging with simultaneous high spatial...

  19. Nanoscale guiding for cold atoms based on surface plasmons along the tips of metallic wedges

    Institute of Scientific and Technical Information of China (English)

    Wang Zheng-Ling; Tang Wei-Min; Zhou Ming; Gao Chuan-Yu

    2013-01-01

    We propose a novel scheme to guide neutral cold atoms in a nanoscale region based on surface plasmons (SPs) of one pair and two pairs of tips of metallic wedges with locally enhanced light intensity and sub-optical wavelength resolution.We analyze the near-field intensity distribution of the tip of the metallic wedge by the FDTD method,and study the total intensity as well as the total potential of optical potentials and van der Waals potentials for 87Rb atoms in the light field of one pair and two pairs of tips of metallic wedges.It shows that the total potentials of one pair and two pairs of tips of metallic wedges can generate a gravito-optical trap and a dark closed trap for nanoscale guiding of neutral cold atoms.Guided atoms can be cooled with efficient intensity-gradient Sisyphus cooling by blue-detuned light field.This provides an important step towards the generation of hybrid systems consisting of isolated atoms and solid devices.

  20. Laser cooling atoms to indistinguishability: Atomic Hong-Ou-Mandel interference and entanglement through spin exchange

    Science.gov (United States)

    Kaufman, Adam

    2016-05-01

    Motional control of neutral atoms has a rich history and increasingly interest has turned to single-atom control. In my thesis work, we created a platform to individually prepare single bosonic atoms in highly pure quantum states, by developing methods to laser cool single atoms to the vibrational ground state of optical tweezer traps. Applying this toolset, we observe the atomic Hong-Ou-Mandel effect when we arrange for atom tunneling to play the role of a balanced beam splitter between two optical tweezers. In another experiment, we utilize spin exchange to create entanglement, which we then verify after spatially separating the atoms to observe their non-local correlations. Merging these results with our recent demonstration of deterministic loading of atomic arrays, our results establish the concept of quantum gas assembly, which could be applied to a variety of systems ranging from the production of single dipolar molecules to the assembly of low-entropy arrays of atoms.

  1. Optically pumped atoms

    CERN Document Server

    Happer, William; Walker, Thad

    2010-01-01

    Covering the most important knowledge on optical pumping of atoms, this ready reference is backed by numerous examples of modelling computation for optical pumped systems. The authors show for the first time that modern scientific computing software makes it practical to analyze the full, multilevel system of optically pumped atoms. To make the discussion less abstract, the authors have illustrated key points with sections of MATLAB codes. To make most effective use of contemporary mathematical software, it is especially useful to analyze optical pumping situations in the Liouville spa

  2. Measuring Low Fluxes of Photons, Neutral Molecules and Ions with a New Generation of Detectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new detector evaluation method (DEM) is proposed to determine the response of graphene detectors to low fluxes of photons, neutral atoms/molecules, and ions in the...

  3. The Weak Neutral Current

    CERN Document Server

    Erler, Jens

    2013-01-01

    This is a review of electroweak precision physics with particular emphasis on low-energy precision measurements in the neutral current sector of the electroweak theory and includes future experimental prospects and the theoretical challenges one faces to interpret these observables. Within the minimal Standard Model they serve as determinations of the weak mixing angle which are competitive with and complementary to those obtained near the Z-resonance. In the context of new physics beyond the Standard Model these measurements are crucial to discriminate between models and to reduce the allowed parameter space within a given model. We illustrate this for the minimal supersymmetric Standard Model with or without R-parity.

  4. Mod en neutral seksualitet!

    DEFF Research Database (Denmark)

    Leer, Jonatan

    2013-01-01

    the paradigm”. This notion was presented at a series of lectures at Collège de France in 1977. Through a reading of Barthes’s autobiography, Roland Barthes par Roland Barthes (1975), the article demonstrates how Barthes in this text tries to outplay the paradigms that rules over the hegemonic understanding...... of gender and sexuality; also the fragmented text presents a vision of a sexual utopia, a neutral sexuality, that tries – like the queer theory – to go and think beyond a binary conception of gender and sexuality. Finally, it is suggested that we should start to think about a movement of “French queer...

  5. Atomic physics

    CERN Document Server

    Born, Max

    1989-01-01

    The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.

  6. Atomic Calligraphy

    Science.gov (United States)

    Imboden, Matthias; Pardo, Flavio; Bolle, Cristian; Han, Han; Tareen, Ammar; Chang, Jackson; Christopher, Jason; Corman, Benjamin; Bishop, David

    2013-03-01

    Here we present a MEMS based method to fabricate devices with a small number of atoms. In standard semiconductor fabrication, a large amount of material is deposited, after which etching removes what is not wanted. This technique breaks down for structures that approach the single atom limit, as it is inconceivable to etch away all but one atom. What is needed is a bottom up method with single or near single atom precision. We demonstrate a MEMS device that enables nanometer position controlled deposition of gold atoms. A digitally driven plate is swept as a flux of gold atoms passes through an aperture. Appling voltages on four comb capacitors connected to the central plate by tethers enable nanometer lateral precision in the xy plane over 15x15 sq. microns. Typical MEMS structures have manufacturing resolutions on the order of a micron. Using a FIB it is possible to mill apertures as small as 10 nm in diameter. Assuming a low incident atomic flux, as well as an integrated MEMS based shutter with microsecond response time, it becomes possible to deposit single atoms. Due to their small size and low power consumption, such nano-printers can be mounted directly in a cryogenic system at ultrahigh vacuum to deposit clean quench condensed metallic structures.

  7. Quantum information with Rydberg atoms

    DEFF Research Database (Denmark)

    Saffman, Mark; Walker, T.G.; Mølmer, Klaus

    2010-01-01

    qubits. The availability of a strong long-range interaction that can be coherently turned on and off is an enabling resource for a wide range of quantum information tasks stretching far beyond the original gate proposal. Rydberg enabled capabilities include long-range two-qubit gates, collective encoding...... of multiqubit registers, implementation of robust light-atom quantum interfaces, and the potential for simulating quantum many-body physics. The advances of the last decade are reviewed, covering both theoretical and experimental aspects of Rydberg-mediated quantum information processing.......Rydberg atoms with principal quantum number n»1 have exaggerated atomic properties including dipole-dipole interactions that scale as n4 and radiative lifetimes that scale as n3. It was proposed a decade ago to take advantage of these properties to implement quantum gates between neutral atom...

  8. Is /h/ phonetically neutral?

    Science.gov (United States)

    Robb, Michael P; Chen, Yang

    2009-11-01

    Use of /h/ in the phrase, 'Say /hVC/ again' has been tacitly assumed to provide a neutral phonetic context in which to study the articulatory characteristics of speech either preceding or following /h/ articulation. Yet, assessment of the stability or neutrality of /h/ has gone untested. The current study sought to determine whether articulation of /h/ differs according to sex and language accent, as well as to examine its influence on subsequent vowel articulation. Selected acoustic features of /hVC/ were measured in 40 speakers of American English (AE) and 40 speakers of Mandarin-accented English (MAE). Results of an analysis of /h/ duration revealed no sex differences within each language group, however considerable variation was found according to accented vs unaccented English. Clear sex differences were found for the production of /h/, occurring more often among male speakers regardless of language variety. Considerable variation in production of /h/ was found between language groups. Analysis of vowel formant frequencies immediately following /h/ articulation indicated minimal coarticulatory effects for both AE and MAE speakers. The present results appear to support the suggestion that /h/ is not exclusively sex-linked and may indeed vary according to non-biological factors. In spite of these variations, /h/ articulation appears to have a negligible influence on neighbouring vowel articulation.

  9. Charge Qubit-Atom Hybrid

    CERN Document Server

    Yu, Deshui; Hufnagel, C; Kwek, L C; Amico, Luigi; Dumke, R

    2016-01-01

    We investigate a novel hybrid system of a superconducting charge qubit interacting directly with a single neutral atom via electric dipole coupling. Interfacing of the macroscopic superconducting circuit with the microscopic atomic system is accomplished by varying the gate capacitance of the charge qubit. To achieve strong interaction, we employ two Rydberg states with an electric-dipole-allowed transition, which alters the polarizability of the dielectric medium of the gate capacitor. Sweeping the gate voltage with different rates leads to a precise control of hybrid quantum states. Furthermore, we show a possible implementation of a universal two-qubit gate.

  10. The Low Energy Neutral Imager (LENI)

    Science.gov (United States)

    Westlake, J. H.; Mitchell, D. G.; Clark, G. B.; Brandt, P. C.; Hoffer, E.

    2016-12-01

    To achieve breakthroughs in the areas of heliospheric and magnetospheric energetic neutral atom (ENA) imaging a new class of instruments is required. We present a high angular resolution ENA imager concept aimed at the suprathermal plasma populations with energies between 0.5 and 20 keV. This instrument is intended for high-spatial resolution ENA imaging of suprathermal plasmas. This technique could be used to understand the spatial and temporal structure of the heliospheric boundary recently revealed by Interstellar Boundary Explorer (IBEX) instrumentation and the Cassini Ion and Neutral Camera (INCA). The instrument is also well suited to characterize magnetospheric ENA emissions from low-altitude ENAs produced by precipitation of magnetospheric ions into the terrestrial upper atmosphere, or from energetic tails of ion outflow, or from the magnetosheath where solar wind protons are neutralized by charge exchange, or from the ring-current region. We present a new technique utilizing ultra-thin carbon foils, 2D collimation using a curved microchannel plate, and a novel electron optical design to produce high-angular resolution (≤2°) and high-sensitivity (≥ 10-3 cm2 sr/pixel) ENA imaging in the 0.5-20 keV energy range.

  11. The impact of exospheric neutral dynamics on ring current decay

    Science.gov (United States)

    Ilie, R.; Liemohn, M. W.; Skoug, R. M.; Funsten, H. O.; Gruntman, M.; Bailey, J. J.; Toth, G.

    2015-12-01

    The geocorona plays an important role in the energy budget of the Earth's inner magnetosphere since charge exchange of energetic ions with exospheric neutrals makes the exosphere act as an energy sink for ring current particles. Long-term ring current decay following a magnetic storm is mainly due to these electron transfer reactions, leading to the formation energetic neutral atoms (ENAs) that leave the ring current system on ballistic trajectories. The number of ENAs emitted from a given region of space depends on several factors, such as the energy and species of the energetic ion population in that region and the density of the neutral gas with which the ions undergo charge exchange. However, the density and structure of the exosphere are strongly dependent on changes in atmospheric temperature and density as well as charge exchange with the ions of plasmaspheric origin, which depletes the geocorona (by having a neutral removed from the system). Moreover, the radiation pressure exerted by solar far-ultraviolet photons pushes the geocoronal hydrogen away from the Earth in an anti-sunward direction to form a tail of neutral hydrogen. TWINS ENA images provide a direct measurement of these ENA losses and therefore insight into the dynamics of the ring current decay through interactions with the geocorona. We assess the influence of geocoronal neutrals on ring current formation and decay by analysis of the predicted ENA emissions using 6 different geocoronal models and simulations from the HEIDI ring current model during storm time. Comparison with TWINS ENA images shows that the location of the peak ENA enhancements is highly dependent on the distribution of geocoronal hydrogen density. We show that the neutral dynamics has a strong influence on the time evolution of the ring current populations as well as on the formation of energetic neutral atoms.

  12. Collisional Cooling of Light Ions by Cotrapped Heavy Atoms.

    Science.gov (United States)

    Dutta, Sourav; Sawant, Rahul; Rangwala, S A

    2017-03-17

    We experimentally demonstrate cooling of trapped ions by collisions with cotrapped, higher-mass neutral atoms. It is shown that the lighter ^{39}K^{+} ions, created by ionizing ^{39}K atoms in a magneto-optical trap (MOT), when trapped in an ion trap and subsequently allowed to cool by collisions with ultracold, heavier ^{85}Rb atoms in a MOT, exhibit a longer trap lifetime than without the localized ^{85}Rb MOT atoms. A similar cooling of trapped ^{85}Rb^{+} ions by ultracold ^{133}Cs atoms in a MOT is also demonstrated in a different experimental configuration to validate this mechanism of ion cooling by localized and centered ultracold neutral atoms. Our results suggest that the cooling of ions by localized cold atoms holds for any mass ratio, thereby enabling studies on a wider class of atom-ion systems irrespective of their masses.

  13. The morphology and kinematics of neutral hydrogen in the vicinity of z=0 galaxies with Milky Way masses -- a study with the Illustris simulation

    CERN Document Server

    Kauffmann, Guinevere; Borthakur, Sanchayeeta

    2016-01-01

    We analyze the properties of the circumgalactic gas (CGM) around 120 galaxies with stellar and dark matter halo masses similar to that of the Milky Way. We focus on the morphology and kinematics of the neutral hydrogen and how this depends on f_g, the ratio of gas-to-stellar mass within the optical radius. In gas-rich galaxies with f_g > 0.1, gas temperatures rise slowly from center of the halo out to the virial radius and average neutral gas column densities remain above 10^19 atoms cm^-2 out to radii of 50-70 kpc. In gas-poor galaxies with f_g < 0.1, gas temperatures rise quickly outside the edge of the disk to 10^6 K, and then remain fixed out to radii of 100 kpc. The column density of neutral gas quickly drops below 10^19 atoms cm^-2 at radii of 10 kpc. Neutral gas distributions are also more asymmetric in gas-poor galaxies. Most of the differences between gas-poor and gas-rich galaxies in the Illustris simulation can be attributed to the effects of "radio-mode" AGN feedback. In the Illustris simulatio...

  14. Organic neutralization agents for neutralization-reionization mass spectrometry.

    Science.gov (United States)

    Zhang, M Y; McLafferty, F W

    1992-02-01

    Porter has shown that excited neutrals of specified internal energies can be prepared by neutralization of an ion beam with metal vapors of low ionization potential (IP). For specific problems in neutralization-reionization mass spectrometry, a metal with the desired IP value may not be available, or it may present experimental problems such as a high vaporization temperature, instrument contamination, or detector instability. The use of organic neutralization agents such as tetra-p-anisylethylene (IP = 6.0 eV) can minimize these problems (although cross sections for neutralization with these are a factor of 5 lower than those with metals), and can provide a much wider range of IP values. Their utility is demonstrated in the neutralization of C4H4 (+•) and CH8 (+•) ions to produce C4H4 and C4H8 of selected internal energies. However, for CH4 (+•) neutralization, the CH4 neutrals formed have a much lower internal energy than predicted, indicating that electron transfer from the neutralization agent predominantly produces its ions in excited states.

  15. Kinetic Atom.

    Science.gov (United States)

    Wilson, David B.

    1981-01-01

    Surveys the research of scientists like Joule, Kelvin, Maxwell, Clausius, and Boltzmann as it comments on the basic conceptual issues involved in the development of a more precise kinetic theory and the idea of a kinetic atom. (Author/SK)

  16. Strange neutral currents in nuclei

    CERN Document Server

    Ressell, M T; Aufderheide, M B; Bloom, S D; Resler, D A

    1995-01-01

    We examine the effects on the nuclear neutral current Gamow-Teller (GT) strength of a finite contribution from a polarized strange quark sea. We perform nuclear shell model calculations of the neutral current GT strength for a number of nuclei likely to be present during stellar core collapse. We compare the GT strength when a finite strange quark contribution is included to the strength without such a contribution. As an example, the process of neutral current nuclear de-excitation via \

  17. Atomic entanglement and decoherence

    Science.gov (United States)

    Genes, Claudiu

    The generation of entanglement in atomic systems plays a central topic in the fields of quantum information storage and processing. Moreover, a special category of entangled states of multi-atom ensembles, spin squeezed states, have been proven to lead to considerable improvement in the sensitivity of precision measurements compared to systems involving uncorrelated atoms. A treatment of entanglement in open systems is, however, incomplete without a precise description of the process of decoherence which necessarily accompanies it. The theory of entanglement and decoherence are the two main topics of this thesis. Methods are described for the generation of strong correlations in large atomic ensembles using either cavity quantum electrodynamics or measurement outcome conditioned quantum dynamics. Moreover, the description of loss of entanglement resulting from the coupling to a noise reservoir (electromagnetic vacuum) is explored. A spin squeezing parameter is used throughout this thesis as both a measure of entanglement strength and as an indication of the sensitivity improvement above the so-called standard quantum limit (sensitivity obtained with uncorrelated particles) in metrology. The first scheme considered consists of a single mode cavity field interacting with a collection of atoms for which spin squeezing is produced in both resonant and off-resonant regimes. In the resonant case, transfer of squeezing from a field state to the atoms is analyzed, while in the off-resonant regime squeezing is produced via an effective nonlinear interaction (one-axis twisting Hamiltonian). A second, more experimentally realistic case, is one involving the interaction of free space atoms with laser pulses; a projective measurement of a source field originating from atomic fluctuations provides a means of preparing atomic collective states such as spin squeezed and Schrodinger cat states. A new "unravelling" is proposed, that employs the detection of photon number in a single

  18. Midplane neutral density profiles in the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Stotler, D. P., E-mail: dstotler@pppl.gov; Bell, R. E.; Diallo, A.; LeBlanc, B. P.; Podestà, M.; Roquemore, A. L.; Ross, P. W. [Princeton Plasma Physics Laboratory, Princeton University, P. O. Box 451, Princeton, New Jersey 08543-0451 (United States); Scotti, F. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2015-08-15

    Atomic and molecular density data in the outer midplane of NSTX [Ono et al., Nucl. Fusion 40, 557 (2000)] are inferred from tangential camera data via a forward modeling procedure using the DEGAS 2 Monte Carlo neutral transport code. The observed Balmer-β light emission data from 17 shots during the 2010 NSTX campaign display no obvious trends with discharge parameters such as the divertor Balmer-α emission level or edge deuterium ion density. Simulations of 12 time slices in 7 of these discharges produce molecular densities near the vacuum vessel wall of 2–8 × 10{sup 17 }m{sup −3} and atomic densities ranging from 1 to 7 × 10{sup 16 }m{sup −3}; neither has a clear correlation with other parameters. Validation of the technique, begun in an earlier publication, is continued with an assessment of the sensitivity of the simulated camera image and neutral densities to uncertainties in the data input to the model. The simulated camera image is sensitive to the plasma profiles and virtually nothing else. The neutral densities at the vessel wall depend most strongly on the spatial distribution of the source; simulations with a localized neutral source yield densities within a factor of two of the baseline, uniform source, case. The uncertainties in the neutral densities associated with other model inputs and assumptions are ≤50%.

  19. Rydberg States of Atoms and Molecules

    Science.gov (United States)

    Stebbings, R. F.; Dunning, F. B.

    2011-03-01

    List of contributors; Preface; 1. Rydberg atoms in astrophysics A. Dalgarno; 2. Theoretical studies of hydrogen Rydberg atoms in electric fields R. J. Damburg and V. V. Kolosov; 3. Rydberg atoms in strong fields D. Kleppner, Michael G. Littman and Myron L. Zimmerman; 4. Spectroscopy of one- and two-electron Rydberg atoms C. Fabre and S. Haroche; 5. Interaction of Rydberg atoms with blackbody radiation T. F. Gallagher; 6. Theoretical approaches to low-energy collisions of Rydberg atoms with atoms and ions A. P. Hickman, R. E. Olson and J. Pascale; 7. Experimental studies of the interaction of Rydberg atoms with atomic species at thermal energies F. Gounand and J. Berlande; 8. Theoretical studies of collisions of Rydberg atoms with molecules Michio Matsuzawa; 9. Experimental studies of thermal-energy collisions of Rydberg atoms with molecules F. B. Dunning and R. F. Stebbings; 10. High-Rydberg molecules Robert S. Freund; 11. Theory of Rydberg collisions with electrons, ions and neutrals M. R. Flannery; 12. Experimental studies of the interactions of Rydberg atoms with charged particles J. -F. Delpech; 13. Rydberg studies using fast beams Peter M. Koch; Index.

  20. CO2-neutral fuels

    Science.gov (United States)

    Goede, A. P. H.

    2015-08-01

    The need for storage of renewable energy (RE) generated by photovoltaic, concentrated solar and wind arises from the fact that supply and demand are ill-matched both geographically and temporarily. This already causes problems of overcapacity and grid congestion in countries where the fraction of RE exceeds the 20% level. A system approach is needed, which focusses not only on the energy source, but includes conversion, storage, transport, distribution, use and, last but not least, the recycling of waste. Furthermore, there is a need for more flexibility in the energy system, rather than relying on electrification, integration with other energy systems, for example the gas network, would yield a system less vulnerable to failure and better adapted to requirements. For example, long-term large-scale storage of electrical energy is limited by capacity, yet needed to cover weekly to seasonal demand. This limitation can be overcome by coupling the electricity net to the gas system, considering the fact that the Dutch gas network alone has a storage capacity of 552 TWh, sufficient to cover the entire EU energy demand for over a month. This lecture explores energy storage in chemicals bonds. The focus is on chemicals other than hydrogen, taking advantage of the higher volumetric energy density of hydrocarbons, in this case methane, which has an approximate 3.5 times higher volumetric energy density. More importantly, it allows the ready use of existing gas infrastructure for energy storage, transport and distribution. Intermittent wind electricity generated is converted into synthetic methane, the Power to Gas (P2G) scheme, by splitting feedstock CO2 and H2O into synthesis gas, a mixture of CO and H2. Syngas plays a central role in the synthesis of a range of hydrocarbon products, including methane, diesel and dimethyl ether. The splitting is accomplished by innovative means; plasmolysis and high-temperature solid oxygen electrolysis. A CO2-neutral fuel cycle is

  1. CO2-neutral fuels

    Directory of Open Access Journals (Sweden)

    Goede A. P. H.

    2015-01-01

    Full Text Available The need for storage of renewable energy (RE generated by photovoltaic, concentrated solar and wind arises from the fact that supply and demand are ill-matched both geographically and temporarily. This already causes problems of overcapacity and grid congestion in countries where the fraction of RE exceeds the 20% level. A system approach is needed, which focusses not only on the energy source, but includes conversion, storage, transport, distribution, use and, last but not least, the recycling of waste. Furthermore, there is a need for more flexibility in the energy system, rather than relying on electrification, integration with other energy systems, for example the gas network, would yield a system less vulnerable to failure and better adapted to requirements. For example, long-term large-scale storage of electrical energy is limited by capacity, yet needed to cover weekly to seasonal demand. This limitation can be overcome by coupling the electricity net to the gas system, considering the fact that the Dutch gas network alone has a storage capacity of 552 TWh, sufficient to cover the entire EU energy demand for over a month. This lecture explores energy storage in chemicals bonds. The focus is on chemicals other than hydrogen, taking advantage of the higher volumetric energy density of hydrocarbons, in this case methane, which has an approximate 3.5 times higher volumetric energy density. More importantly, it allows the ready use of existing gas infrastructure for energy storage, transport and distribution. Intermittent wind electricity generated is converted into synthetic methane, the Power to Gas (P2G scheme, by splitting feedstock CO2 and H2O into synthesis gas, a mixture of CO and H2. Syngas plays a central role in the synthesis of a range of hydrocarbon products, including methane, diesel and dimethyl ether. The splitting is accomplished by innovative means; plasmolysis and high-temperature solid oxygen electrolysis. A CO2-neutral fuel

  2. Excited ionic and neutral fragments produced by dissociation of the N2(+)-asterisk H band

    Science.gov (United States)

    Samson, James A. R.; Chung, Y.; Lee, E.-M.

    1991-01-01

    Atomic fluorescence produced by dissociative photoionization of N2 was observed and identified in experiments where fluorescent radiation was produced by irradiating N2 gas with undispersed synchrotron radiation. The spectrum was detected with a multichannel plate electron multiplier. Evidence is presented that the H band of N2(+)-asterisk does predissociate into excited neutral and ionic atoms.

  3. Atomic and molecular processes in fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Janev, R.K. [International Atomic Energy Agency, Vienna (Austria)

    1997-01-01

    The role of atomic and molecular processes in achieving and maintaining the conditions for thermonuclear burn in a magnetically confined fusion plasma is described. Emphasis is given to the energy balance and power and particle exhaust issues. The most important atomic and molecular processes which affect the radiation losses and impurity transport in the core plasma, the neutral particle transport in the plasma edge and the radiative cooling of divertor plasmas are discussed in greater detail. (author)

  4. Spin-sensitive atom mirror via spin-orbit interaction

    Science.gov (United States)

    Zhou, Lu; Zheng, Ren-Fei; Zhang, Weiping

    2016-11-01

    Based on the spin-orbit coupling recently implemented in a neutral cold-atom gas, we propose a scheme to realize spin-dependent scattering of cold atoms. In particular we consider a matter wave packet of cold-atom gas impinging upon a step potential created by the optical light field, inside of which the atoms are subject to spin-orbit interaction. We show that the proposed system can act as a spin polarizer or spin-selective atom mirror for the incident atomic beam. The principle and the operating parameter regime of the system are carefully discussed.

  5. The merits of neutral theory

    NARCIS (Netherlands)

    Alonso, David; Etienne, Rampal S.; McKane, Alan J.

    2006-01-01

    Hubbell's neutral theory of biodiversity has challenged the classic niche-based view of ecological community structure. Although there have been many attempts to falsify Hubbell's theory, we argue that falsification should not lead to rejection, because there is more to the theory than neutrality al

  6. The merits of neutral theory

    NARCIS (Netherlands)

    Alonso, D.; Etienne, R.S.; McKane, A.J.

    2006-01-01

    Hubbell's neutral theory of biodiversity has challenged the classic niche-based view of ecological community structure. Although there have been many attempts to falsify Hubbell's theory, we argue that falsification should not lead to rejection, because there is more to the theory than neutrality al

  7. Eliminating light shifts for single atom trapping

    Science.gov (United States)

    Hutzler, Nicholas R.; Liu, Lee R.; Yu, Yichao; Ni, Kang-Kuen

    2017-02-01

    Microscopically controlled neutral atoms in optical tweezers and lattices have led to exciting advances in the study of quantum information and quantum many-body systems. The light shifts of atomic levels from the trapping potential in these systems can result in detrimental effects such as fluctuating dipole force heating, inhomogeneous detunings, and inhibition of laser cooling, which limits the atomic species that can be manipulated. In particular, these light shifts can be large enough to prevent loading into optical tweezers directly from a magneto-optical trap. We implement a general solution to these limitations by loading, as well as cooling and imaging the atoms with temporally alternating beams, and present an analysis of the role of heating and required cooling for single atom tweezer loading. Because this technique does not depend on any specific spectral properties, it should enable the optical tweezer platform to be extended to nearly any atomic or molecular species that can be laser cooled and optically trapped.

  8. Nanostructured optical nanofibres for atom trapping

    CERN Document Server

    Daly, Mark; Phelan, Ciarán; Deasy, Kieran; Chormaic, Síle Nic

    2013-01-01

    We propose an optical dipole trap for cold neutral atoms based on the electric field produced from the evanescent fields in a hollow rectangular slot cut through an optical nanofibre. In particular, we discuss the trap performance in relation to laser-cooled rubidium atoms and show that a far off-resonance, blue-detuned field combined with the attractive surface-atom interaction potential from the dielectric material forms a stable trapping configuration. With the addition of a red-detuned field, we demonstrate how three dimensional confinement of the atoms at a distance of 140 - 200 nm from the fibre surface within the slot can be accomplished. This scheme facilitates optical coupling between the atoms and the nanofibre that could be exploited for quantum communication schemes using ensembles of laser-cooled atoms.

  9. Natural and artificial atoms for quantum computation

    Energy Technology Data Exchange (ETDEWEB)

    Buluta, Iulia; Ashhab, Sahel; Nori, Franco, E-mail: fnori@riken.jp [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan)

    2011-10-15

    Remarkable progress towards realizing quantum computation has been achieved using natural and artificial atoms as qubits. This paper presents a brief overview of the current status of different types of qubits. On the one hand, natural atoms (such as neutral atoms and ions) have long coherence times, and could be stored in large arrays, providing ideal 'quantum memories'. On the other hand, artificial atoms (such as superconducting circuits or semiconductor quantum dots) have the advantage of custom-designed features and could be used as 'quantum processing units'. Natural and artificial atoms can be coupled with each other and can also be interfaced with photons for long-distance communications. Hybrid devices made of natural/artificial atoms and photons may provide the next-generation design for quantum computers.

  10. Nanostructured optical nanofibres for atom trapping

    Science.gov (United States)

    Daly, M.; Truong, V. G.; Phelan, C. F.; Deasy, K.; Chormaic, S. Nic

    2014-05-01

    We propose an optical dipole trap for cold, neutral atoms based on the electric field produced from the evanescent fields in a hollow, rectangular slot cut through an optical nanofibre. In particular, we discuss the trap performance in relation to laser-cooled rubidium atoms and show that a far off-resonance, blue-detuned field combined with the attractive surface-atom interaction potential from the dielectric material forms a stable trapping configuration. With the addition of a red-detuned field, we demonstrate how three dimensional confinement of the atoms at a distance of 140-200 nm from the fibre surface within the slot can be accomplished. This scheme facilitates optical coupling between the atoms and the nanofibre that could be exploited for quantum communication schemes using ensembles of laser-cooled atoms.

  11. Atomic theories

    CERN Document Server

    Loring, FH

    2014-01-01

    Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec

  12. Neutral beam dump with cathodic arc titanium gettering.

    Science.gov (United States)

    Smirnov, A; Krivenko, A S; Murakhtin, S V; Savkin, V Ya; Korepanov, S A; Putvinski, S

    2011-03-01

    An incomplete neutral beam capture can degrade the plasma performance in neutral beam driven plasma machines. The beam dumps mitigating the shine-through beam recycling must entrap and retain large particle loads while maintaining the beam-exposed surfaces clean of the residual impurities. The cathodic arc gettering, which provides high evaporation rate coupled with a fast time response, is a powerful and versatile technique for depositing clean getter films in vacuum. A compact neutral beam dump utilizing the titanium arc gettering was developed for a field-reversed configuration plasma sustained by 1 MW, 20-40 keV neutral hydrogen beams. The titanium evaporator features a new improved design. The beam dump is capable of handling large pulsed gas loads, has a high sorption capacity, and is robust and reliable. With the beam particle flux density of 5 × 10(17) H∕(cm(2) s) sustained for 3-10 ms, the beam recycling coefficient, defined as twice the ratio of the hydrogen molecular flux leaving the beam dump to the incident flux of high-energy neutral atoms, is ∼0.7. The use of the beam dump allows us to significantly reduce the recycling of the shine-through neutral beam as well as to improve the vacuum conditions in the machine.

  13. The Relationship between Neutralization Techniques and Induced Abortion

    Science.gov (United States)

    Kalateh Sadati, Ahmad; Tabei, Seyed Ziaaddin; Salehzadeh, Hamzeh; Rahnavard, Farnaz; Namavar Jahromi, Bahia; Hemmati, Soroor

    2014-01-01

    Background: Induced abortion is not only a serious threat for women’s health, but also a controversial topic for its ethical and moral problems. We aimed to evaluate the relationship between neutralization techniques and attempting to commit abortion in married women with unintended pregnancy. Methods: After in-depth interviews with some women who had attempted abortion, neutralization themes were gathered. Next, to analyze the data quantitatively, a questionnaire was created including demographic and psychosocial variables specifically related to neutralization. The participants were divided into two groups (abortion and control) of unintended pregnancy and were then compared. Results: Analysis of psychosocial variables revealed a significant difference in the two groups at neutralization, showing that neutralization in the control group (56.97±10.24) was higher than that in the abortion group (44.19±12.44). To evaluate the findings more accurately, we examined the causal factors behind the behaviors of the abortion group. Binary logistic regression showed that among psychosocial factors, neutralization significantly affected abortion (95% CI=1.07-1.35). Conclusion: Despite the network of many factors affecting induced abortion, neutralization plays an important role in reinforcing the tendency to attempt abortion. Furthermore, the decline of religious beliefs, as a result of the secular context of the modern world, seems to have an important role in neutralizing induced abortion. PMID:25349851

  14. The Relationship between Neutralization Techniques and Induced Abortion.

    Science.gov (United States)

    Kalateh Sadati, Ahmad; Tabei, Seyed Ziaaddin; Salehzadeh, Hamzeh; Rahnavard, Farnaz; Namavar Jahromi, Bahia; Hemmati, Soroor

    2014-04-01

    Induced abortion is not only a serious threat for women's health, but also a controversial topic for its ethical and moral problems. We aimed to evaluate the relationship between neutralization techniques and attempting to commit abortion in married women with unintended pregnancy. After in-depth interviews with some women who had attempted abortion, neutralization themes were gathered. Next, to analyze the data quantitatively, a questionnaire was created including demographic and psychosocial variables specifically related to neutralization. The participants were divided into two groups (abortion and control) of unintended pregnancy and were then compared. Analysis of psychosocial variables revealed a significant difference in the two groups at neutralization, showing that neutralization in the control group (56.97±10.24) was higher than that in the abortion group (44.19±12.44). To evaluate the findings more accurately, we examined the causal factors behind the behaviors of the abortion group. Binary logistic regression showed that among psychosocial factors, neutralization significantly affected abortion (95% CI=1.07-1.35). Despite the network of many factors affecting induced abortion, neutralization plays an important role in reinforcing the tendency to attempt abortion. Furthermore, the decline of religious beliefs, as a result of the secular context of the modern world, seems to have an important role in neutralizing induced abortion.

  15. General model of depolarization and transfer of polarization of singly ionized atoms by collisions with hydrogen atoms

    CERN Document Server

    Derouich, Moncef

    2016-01-01

    Simulations of the generation of the atomic polarization is necessary for interpreting the second solar spectrum. For this purpose, it is important to rigorously determine the effects of the isotropic collisions with neutral hydrogen on the atomic polarization of the neutral atoms, ionized atoms and molecules. Our aim is to treat in generality the problem of depolarizing isotropic collisions between singly ionized atoms and neutral hydrogen in its ground state. Using our numerical code, we computed the collisional depolarization rates of the $p$-levels of ions for large number of values of the effective principal quantum number $n^{*}$ and the Uns\\"old energy $E_p$. Then, genetic programming has been utilized to fit the available depolarization rates. As a result, strongly non-linear relationships between the collisional depolarization rates, $n^{*}$ and $E_p$ are obtained, and are shown to reproduce the original data with accuracy clearly better than 10\\%. These relationships allow quick calculations of the ...

  16. Experimental and numerical studies of neutral gas depletion in an inductively coupled plasma

    Science.gov (United States)

    Shimada, Masashi

    The central theme of this dissertation is to explore the impact of neutral depletion and coupling between plasma and neutral gas in weakly ionized unmagnetized plasma. Since there have been few systematic studies of the mechanism which leads to non-uniform neutral distribution in processing plasmas, this work investigated the spatial profiles of neutral temperature and pressure experimentally, and the mechanism of resulting neutral depletion by simulation. The experimental work is comprised of neutral temperature measurements using high resolution atomic spectroscopy and molecular spectroscopy, and neutral pressure measurements considering thermal transpiration. When thermal transpiration effects are used to correct the gas pressure measurements, the total pressure remains constant regardless of the plasma condition. Since the neutral gas follows the ideal gas law, the neutral gas density profile is also obtained from the measured neutral gas temperature and the corrected pressure measurements. The results show that neutral gas temperature rises close to ˜ 900 [K], and the neutral gas density at the center of plasma chamber has a significant (factor of 2-4x) decrease in the presence of a plasma discharge. In numerical work, neutral and ion transport phenomena were simulated by a hybrid-type direct simulation Monte Carlo (DSMC) method of one dimensional (1D) electrostatic plasma to identify the mechanism of the neutral gas density depletion in Ar/N2 mixtures. The simulation reveals that the neutral depletion is the result of the interplay between plasma and neutral gas, and a parametric study indicates that neutral depletion occurs mainly due to gas heating and pressure balance for the typical condition of plasma processing. In high density plasma sources (Te ≈ 2-5 eV, ne ≈ 1011-1012 cm-3) where the plasma pressure becomes comparable to neutral pressure, total pressure (neutral pressure and plasma pressure) is conserved before and after the discharge. Therefore

  17. Hollow-atom probing of surfaces

    NARCIS (Netherlands)

    Limburg, J.

    1997-01-01

    This paper discusses the mechanisms governing the formation and decay of hollow atoms in front of (semi) conducting and insulating surfaces. First, the primary neutralization of the highly charged ions is treated in terms of the classical overbarrier model. Different views are presented. Then the mo

  18. Photoelectron spectroscopy of heavy atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    White, M.G.

    1979-07-01

    The importance of relativistic interactions in the photoionization of heavy atoms and molecules has been investigated by the technique of photoelectron spectroscopy. In particular, experiments are reported which illustrate the effects of the spin-orbit interaction in the neutral ground state, final ionic states and continuum states of the photoionization target.

  19. Anion formation in sputter ion sources by neutral resonant ionization

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, J. S., E-mail: johnsvogel@yahoo.com [University of California, 8300 Feliz Creek Dr., Ukiah, California 95482 (United States)

    2016-02-15

    Focused Cs{sup +} beams in sputter ion sources create mm-diameter pits supporting small plasmas that control anionization efficiencies. Sputtering produces overwhelmingly neutral products that the plasma can ionize as in a charge-change vapor. Electron capture between neutral atoms rises as the inverse square of the difference between the ionization potential of the Cs state and the electron affinity of the sputtered atom, allowing resonant ionization at very low energies. A plasma collision-radiation model followed electronic excitation up to Cs(7d). High modeled Cs(7d) in a 0.5 mm recess explains the 80 μA/mm{sup 2} C{sup −} current density compared to the 20 μA/mm{sup 2} from a 1 mm recess.

  20. The Antiparticles of Neutral Bosons

    CERN Document Server

    Perkins, Walton A

    2013-01-01

    With the advent of the ability to create and study antihydrogen, we think it is appropriate to consider the possibility that antiphotons might not be identical to photons. First of all, we will look at the experimental evidence concerning multiple neutral pions and multiple photons. Because of its internal structure, the neutral kaon is not identical to its antiparticle. We will consider internal structures for the neutral pion and photon for which the antiparticle differs from the particle. Interestingly, the antiphoton thus created from neutrinos does not interact with electrons because its neutrinos have the wrong helicity.

  1. Positional nystagmus showing neutral points.

    Science.gov (United States)

    Hiruma, Kiyoshi; Numata, Tsutomu

    2004-01-01

    We encountered patients who had their static direction-changing positional nystagmus canceled at about 20-30 degrees yaw head rotation from the supine position. This nystagmus was also canceled when the head was rotated 180 degrees from this position. We call these head positions neutral points. At the neutral points, the cupula of the horizontal semicircular canal of the affected ear is positioned vertical to the gravitational plane and no deflection of the cupula occurs. The positional nystagmus observed (except the neutral points) was thought to occur due to a "heavy cupula" or "light cupula", which may be determined by the specific gravity of its endolymph.

  2. Analyzing ion distributions around DNA.

    Science.gov (United States)

    Lavery, Richard; Maddocks, John H; Pasi, Marco; Zakrzewska, Krystyna

    2014-07-01

    We present a new method for analyzing ion, or molecule, distributions around helical nucleic acids and illustrate the approach by analyzing data derived from molecular dynamics simulations. The analysis is based on the use of curvilinear helicoidal coordinates and leads to highly localized ion densities compared to those obtained by simply superposing molecular dynamics snapshots in Cartesian space. The results identify highly populated and sequence-dependent regions where ions strongly interact with the nucleic and are coupled to its conformational fluctuations. The data from this approach is presented as ion populations or ion densities (in units of molarity) and can be analyzed in radial, angular and longitudinal coordinates using 1D or 2D graphics. It is also possible to regenerate 3D densities in Cartesian space. This approach makes it easy to understand and compare ion distributions and also allows the calculation of average ion populations in any desired zone surrounding a nucleic acid without requiring references to its constituent atoms. The method is illustrated using microsecond molecular dynamics simulations for two different DNA oligomers in the presence of 0.15 M potassium chloride. We discuss the results in terms of convergence, sequence-specific ion binding and coupling with DNA conformation.

  3. The generation of neutral derivatives of low-valence iron, RFe(I), by netralization-reionization mass spectrometry.

    Science.gov (United States)

    Zagorevski, Dmitri

    2005-01-01

    Neutralization-reionization mass spectrometry is applied for the generation of low-valence iron derivatives. Neutralization of Rfe(+) (R=H, F, Cl, Br, I, CN, OH, NH(2), acac, C(6)H(5)) ions resulted in the corresponding neutrals having lifetimes of at least 5 micros. Atom connectivities in RFe ions and neutrals were elucidated by a variety of tandem mass spectrometry techniques. The present study provides the first experimental evidence of the intrinsic stability of neutral IFe, NCFe, acacFe and C(6)H(5)Fe.

  4. Molecular ions in ultracold atomic gases: computed electronic interactions for \\MgHion with Rb

    CERN Document Server

    Tacconi, Mario

    2007-01-01

    The electronic structures of the manifold of potential energy surfaces generated in the lower energy range by the interaction of the MgH$^+$(X$^1\\Sigma^+$) cationic molecule with Rb($^2$S), neutral atom are obtained over a broad range of Jacobi coordinates from strongly correlated \\emph{ab initio} calculations which use a Multireference (MR) wavefunction within a Complete Active Space (CAS) approach. The relative features of the lowest five surfaces are analyzed in terms of possible collisional outcomes when employed to model the ultracold dynamics of ionic molecular partners.

  5. Analyzing Peace Pedagogies

    Science.gov (United States)

    Haavelsrud, Magnus; Stenberg, Oddbjorn

    2012-01-01

    Eleven articles on peace education published in the first volume of the Journal of Peace Education are analyzed. This selection comprises peace education programs that have been planned or carried out in different contexts. In analyzing peace pedagogies as proposed in the 11 contributions, we have chosen network analysis as our method--enabling…

  6. Holographic generation of micro-trap arrays for single atoms

    CERN Document Server

    Bergamini, S; Jones, M; Jacubowiez, L; Browaeys, A; Grangier, P; Bergamini, Silvia; Darquie, Benoit; Jones, Matt; Jacubowiez, Lionel; Browaeys, Antoine; Grangier, Philippe

    2004-01-01

    We have generated multiple micron-sized optical dipole traps for neutral atoms using holographic techniques with a programmable liquid crystal spatial light modulator. The setup allows the storing of a single atom per trap, and the addressing and manipulation of individual trapping sites.

  7. Cold atom dynamics in crossed laser beam waveguides

    CERN Document Server

    Torrontegui, E; Ruschhaupt, A; Guéry-Odelin, D; Muga, J G

    2010-01-01

    We study the dynamics of neutral cold atoms in an $L$-shaped crossed-beam optical waveguide formed by two perpendicular red-detuned lasers of different intensities and a blue-detuned laser at the corner. Complemented with a vibrational cooling process this setting works as a one-way device or "atom diode".

  8. Spreadsheet-Based Program for Simulating Atomic Emission Spectra

    Science.gov (United States)

    Flannigan, David J.

    2014-01-01

    A simple Excel spreadsheet-based program for simulating atomic emission spectra from the properties of neutral atoms (e.g., energies and statistical weights of the electronic states, electronic partition functions, transition probabilities, etc.) is described. The contents of the spreadsheet (i.e., input parameters, formulas for calculating…

  9. Atomic rivals

    Energy Technology Data Exchange (ETDEWEB)

    Goldschmidt, B.

    1990-01-01

    This book is a memoir of rivalries among the Allies over the bomb, by a participant and observer. Nuclear proliferation began in the uneasy wartime collaboration of the United States, England, Canada, and Free France to produce the atom bomb. Through the changes of history, a young French chemist had a role in almost every act of this international drama. This memoir is based on Goldschmidt's own recollections, interviews with other leading figures, and 3,000 pages of newly declassified documents in Allied archives. From his own start as Marie Curie's lab assistant, Goldschmidt's career was closely intertwined with Frances complicated rise to membership in the nuclear club. As a refugee from the Nazis, he became part of the wartime nuclear energy project in Canada and found himself the only French scientist to work (although briefly) on the American atom bomb project.

  10. Atomic physics

    Energy Technology Data Exchange (ETDEWEB)

    Livingston, A.E.; Kukla, K.; Cheng, S. [Univ. of Toledo, OH (United States)] [and others

    1995-08-01

    In a collaboration with the Atomic Physics group at Argonne and the University of Toledo, the Atomic Physics group at the University of Notre Dame is measuring the fine structure transition energies in highly-charged lithium-like and helium-like ions using beam-foil spectroscopy. Precise measurements of 2s-2p transition energies in simple (few-electron) atomic systems provide stringent tests of several classes of current atomic- structure calculations. Analyses of measurements in helium-like Ar{sup 16+} have been completed, and the results submitted for publication. A current goal is to measure the 1s2s{sup 3}S{sub 1} - 1s2p{sup 3}P{sub 0} transition wavelength in helium-like Ni{sup 26+}. Measurements of the 1s2s{sup 2}S{sub 1/2} - 1s2p{sup 2}P{sub 1/2,3/2} transition wavelengths in lithium-like Kr{sup 33+} is planned. Wavelength and lifetime measurements in copper-like U{sup 63+} are also expected to be initiated. The group is also participating in measurements of forbidden transitions in helium-like ions. A measurement of the lifetime of the 1s2s{sup 3}S{sub 1} state in Kr{sup 34+} was published recently. In a collaboration including P. Mokler of GSI, Darmstadt, measurements have been made of the spectral distribution of the 2E1 decay continuum in helium-like Kr{sup 34+}. Initial results have been reported and further measurements are planned.

  11. Artificial Rydberg atom

    Energy Technology Data Exchange (ETDEWEB)

    Joe, Yong S. [Center for Computational Nanoscience, Department of Physics and Astronomy, Ball State University, Muncie, IN 47306 (United States)], E-mail: ysjoe@bsu.edu; Mkrtchian, Vanik E. [Institute for Physical Research, Armenian Academy of Sciences, Ashtarak-2, 378410, Republic of Armenia (Armenia); Lee, Sun H. [Center for Computational Nanoscience, Department of Physics and Astronomy, Ball State University, Muncie, IN 47306 (United States)

    2009-03-02

    We analyze bound states of an electron in the field of a positively charged nanoshell. We find that the binding and excitation energies of the system decrease when the radius of the nanoshell increases. We also show that the ground and the first excited states of this system have remarkably the same properties of the highly excited Rydberg states of a hydrogen-like atom, i.e., a high sensitivity to the external perturbations and long radiative lifetimes.

  12. Strange exotic atoms

    Science.gov (United States)

    Friedman, E.

    1998-08-01

    Exotic atoms of K- and Σ- are analyzed using density-dependent optical potentials constrained by a low-density limit. Emphasis is placed on radial sensitivities of the real potential. A potential depth of 180MeV inside nuclei is confirmed for K-. For Σ- a shallow attractive potential outside the nuclear surface becomes repulsive in the interior. The information content of limited data sets is demonstrated.

  13. Neutrality Versus Materiality: A Thermodynamic Theory of Neutral Surfaces

    Directory of Open Access Journals (Sweden)

    Rémi Tailleux

    2016-09-01

    Full Text Available In this paper, a theory for constructing quasi-neutral density variables γ directly in thermodynamic space is formulated, which is based on minimising the absolute value of a purely thermodynamic quantity J n . Physically, J n has a dual dynamic/thermodynamic interpretation as the quantity controlling the energy cost of adiabatic and isohaline parcel exchanges on material surfaces, as well as the dependence of in-situ density on spiciness, in a description of water masses based on γ, spiciness and pressure. Mathematically, minimising | J n | in thermodynamic space is showed to be equivalent to maximising neutrality in physical space. The physics of epineutral dispersion is also reviewed and discussed. It is argued, in particular, that epineutral dispersion is best understood as the aggregate effect of many individual non-neutral stirring events (being understood here as adiabatic and isohaline events with non-zero buoyancy, so that it is only the net displacement aggregated over many events that is approximately neutral. This new view resolves an apparent paradox between the focus in neutral density theory on zero-buoyancy motions and the overwhelming evidence that lateral dispersion in the ocean is primarily caused by non-zero buoyancy processes such as tides, residual currents and sheared internal waves. The efficiency by which a physical process contributes to lateral dispersion can be characterised by its energy signature, with those processes releasing available potential energy (negative energy cost being more efficient than purely neutral processes with zero energy cost. The latter mechanism occurs in the wedge of instability, and its source of energy is the coupling between baroclinicity, thermobaricity, and density compensated temperature/salinity anomalies. Such a mechanism, which can only exist in a salty ocean, is speculated to be important for dissipating spiciness anomalies and neutral helicity. The paper also discusses potential

  14. A Novel Neutral Point Voltage Control Strategy for Three-Level NPC APF Based on SVPWM

    Directory of Open Access Journals (Sweden)

    Yao Xiaolong

    2015-01-01

    Full Text Available The unbalance of the neutral point voltage is an inherent problem of three-level neutral-point-clamped (NPC Active Power Filter (APF; this paper analyzes the causes of unbalanced neutral point voltage and studies the reason of the unbalance of the neutral point voltage. A novel neutral point voltage control strategy using Space Vector Pulse Width Modulation (SVPWM is proposed. The proposed strategy is based on the traditional SVPWM, by controlling the effect time of small vector, which can change the state of the midpoint voltage fluctuation, and the neutral point voltage can be maintained balance. The influence of the vector on neutral point balance is investigated in depth. Simulation results show the neutral point voltage balancing control strategy based on SPWM is effective.

  15. Incomplete Neutralization and Deviation from Sigmoidal Neutralization Curves for HIV Broadly Neutralizing Monoclonal Antibodies.

    Directory of Open Access Journals (Sweden)

    Laura E McCoy

    2015-08-01

    Full Text Available The broadly neutralizing HIV monoclonal antibodies (bnMAbs PG9, PG16, PGT151, and PGT152 have been shown earlier to occasionally display an unusual virus neutralization profile with a non-sigmoidal slope and a plateau at <100% neutralization. In the current study, we were interested in determining the extent of non-sigmoidal slopes and plateaus at <100% for HIV bnMAbs more generally. Using both a 278 panel of pseudoviruses in a CD4 T-cell (U87.CCR5.CXCR4 assay and a panel of 117 viruses in the TZM-bl assay, we found that bnMAbs targeting many neutralizing epitopes of the spike had neutralization profiles for at least one virus that plateaued at <90%. Across both panels the bnMAbs targeting the V2 apex of Env and gp41 were most likely to show neutralization curves that plateaued <100%. Conversely, bnMAbs targeting the high-mannose patch epitopes were less likely to show such behavior. Two CD4 binding site (CD4bs Abs also showed this behavior relatively infrequently. The phenomenon of incomplete neutralization was also observed in a large peripheral blood mononuclear cells (PBMC-grown molecular virus clone panel derived from patient viral swarms. In addition, five bnMAbs were compared against an 18-virus panel of molecular clones produced in 293T cells and PBMCs and assayed in TZM-bl cells. Examples of plateaus <90% were seen with both types of virus production with no consistent patterns observed. In conclusion, incomplete neutralization and non-sigmoidal neutralization curves are possible for all HIV bnMAbs against a wide range of viruses produced and assayed in both cell lines and primary cells with implications for the use of antibodies in therapy and as tools for vaccine design.

  16. The Effect of Multipole-Enhanced Diffusion on the Joule Heating of a Cold Non-Neutral Plasma

    CERN Document Server

    Chapman, Steven Francis

    One proposed technique for trapping anti-atoms is to superimpose a Ioffe-Pritchard style magnetic-minimum neutral trap on a standard Penning trap used to trap the charged atomic constituents. Adding a magnetic multipole field in this way removes the azimuthal symmetry of the ideal Penning trap and introduces a new avenue for radial diffusion. Enhanced diffusion will lead to increased Joule heating of a non-neutral plasma, potentially adversely affecting the formation rate of anti-atoms and increasing the required trap depth. We present a model of this effect, along with an approach to minimizing it, with comparison to measurements from an intended anti-atom trap.

  17. Neutral theory in community ecology

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    One of the central goals of community ecology is to understand the forces that maintain species diversity within communities. The traditional niche-assembly theory asserts that species live together in a community only when they differ from one another in resource uses. But this theory has some difficulties in explaining the diversity often observed in specie-rich communities such as tropical forests. As an alternative to the niche theory, Hubbell and other ecologists introduced a neutral model. Hubbell argues that the number of species in a community is controlled by species extinction and immigration or speciation of new species. Assuming that all individuals of all species in a trophically similar com-munity are ecologically equivalent, Hubbell's neutral theory predicts two important statistical distributions. One is the asymptotic log-series distribution for the metacommunities under point mutation speciation, and the other is the zero-sum multinomial distribution for both local communities under dispersal limitation and metacommunities under random fission speciation. Unlike the niche-assembly theory, the neutral theory takes similarity in species and individuals as a starting point for investigating species diversity. Based on the fundamental processes of birth, death, dispersal and spe-ciation, the neutral theory provided the first mechanistic explanation of species abundance distribution commonly observed in natural communities. Since the publication of the neutral theory, there has been much discussion about it, pro and con. In this paper, we summarize recent progress in the assumption, prediction and speciation mode of the neutral theory, including progress in the theory itself, tests about the assumption of the theory, prediction and speciation mode at the metacommunity level. We also suggest that the most important task in the future is to bridge the niche-assembly theory and the neutral theory, and to add species differences to the neutral theory and

  18. Vendor neutral archive in PACS

    Directory of Open Access Journals (Sweden)

    Tapesh Kumar Agarwal

    2012-01-01

    Full Text Available An archive is a location containing a collection of records, documents, or other materials of historical importance. An integral part of Picture Archiving and Communication System (PACS is archiving. When a hospital needs to migrate a PACS vendor, the complete earlier data need to be migrated in the format of the newly procured PACS. It is both time and money consuming. To address this issue, the new concept of vendor neutral archive (VNA has emerged. A VNA simply decouples the PACS and workstations at the archival layer. This is achieved by developing an application engine that receives, integrates, and transmits the data using the different syntax of a Digital Imaging and Communication in Medicine (DICOM format. Transferring the data belonging to the old PACS to a new one is performed by a process called migration of data. In VNA, a number of different data migration techniques are available to facilitate transfer from the old PACS to the new one, the choice depending on the speed of migration and the importance of data. The techniques include simple DICOM migration, prefetch-based DICOM migration, medium migration, and the expensive non-DICOM migration. "Vendor neutral" may not be a suitable term, and "architecture neutral," "PACS neutral," "content neutral," or "third-party neutral" are probably better and preferred terms. Notwithstanding this, the VNA acronym has come to stay in both the medical IT user terminology and in vendor nomenclature, and radiologists need to be aware of its impact in PACS across the globe.

  19. Torsional Alfven waves in solar partially ionized plasma: effects of neutral helium and stratification

    CERN Document Server

    Zaqarashvili, T V; Soler, R

    2012-01-01

    Ion-neutral collisions may lead to the damping of Alfven waves in chromospheric and prominence plasmas. Neutral helium atoms enhance the damping in certain temperature interval, where the ratio of neutral helium and neutral hydrogen atoms is increased. Therefore, the height-dependence of ionization degrees of hydrogen and helium may influence the damping rate of Alfven waves. We aim to study the effect of neutral helium in the damping of Alfven waves in stratified partially ionized plasma of the solar chromosphere. We consider a magnetic flux tube, which is expanded up to 1000 km height and then becomes vertical due to merging with neighboring tubes, and study the dynamics of linear torsional Alfven waves in the presence of neutral hydrogen and neutral helium atoms. We start with three-fluid description of plasma and consequently derive single-fluid magnetohydrodynamic (MHD) equations for torsional Alfven waves. Thin flux tube approximation allows to obtain the dispersion relation of the waves in the lower pa...

  20. Analyzing in the present

    DEFF Research Database (Denmark)

    Revsbæk, Line; Tanggaard, Lene

    2015-01-01

    The article presents a notion of “analyzing in the present” as a source of inspiration in analyzing qualitative research materials. The term emerged from extensive listening to interview recordings during everyday commuting to university campus. Paying attention to the way different parts...... the interdependency between researcher and researched. On this basis, we advocate an explicit “open-state-of mind” listening as a key aspect of analyzing qualitative material, often described only as a matter of reading transcribed empirical materials, reading theory, and writing. The article contributes...

  1. Laser spectroscopy of atomic radium

    Energy Technology Data Exchange (ETDEWEB)

    Groot, Alexander; Jungmann, Klaus; Santra, Bodhaditya; Willmann, Lorenz; Wilschut, Hans W. [KVI, University of Groningen (Netherlands)

    2009-07-01

    The heavy alkaline earth elements radium (Ra) offers a unique sensitivity to a parity and time reversal violating permanent electric dipole moments (EDM). In particular, Ra exhibits the largest known atomic enhancements factors for EDMs. The intrinsic sensitivity arises from the specific atomic and nuclear structure of Ra. All Ra isotopes with nuclear spin I are radioactive. The lifetimes are shorter than 15 d. Several Ra isotopes are available at the TRI{mu}P facility at KVI. For the exploitation of the sensitivity Ra atoms have to be collected in a neutral atom trap. The main laser cooling is done on the strong {sup 1}S{sub 0}-{sup 1}P{sub 1} transition at 482.7 nm, similar to the laser cooling and trapping of the chemical homologue barium. Laser spectroscopy of the strong {sup 1}S{sub 0}-{sup 1}P{sub 1} transitions is presented. The light at this wavelength is provided by frequency doubling of a Ti:sapphire laser in a KNbO{sub 3} crystal. Of particular interest is the decay branching of the excited state to the metastable D-states. Such measurements are indispensable input for current atomic structure calculations, which are necessary for the analysis of a EDM measurement using Ra.

  2. Observation of relativistic antihydrogen atoms

    Energy Technology Data Exchange (ETDEWEB)

    Blanford, Glenn DelFosse

    1998-01-01

    An observation of relativistic antihydrogen atoms is reported in this dissertation. Experiment 862 at Fermi National Accelerator Laboratory observed antihydrogen atoms produced by the interaction of a circulating beam of high momentum (3 < p < 9 GeV/c) antiprotons and a jet of molecular hydrogen gas. Since the neutral antihydrogen does not bend in the antiproton source magnets, the detectors could be located far from the interaction point on a beamline tangent to the storage ring. The detection of the antihydrogen is accomplished by ionizing the atoms far from the interaction point. The positron is deflected by a magnetic spectrometer and detected, as are the back to back photons resulting from its annihilation. The antiproton travels a distance long enough for its momentum and time of flight to be measured accurately. A statistically significant sample of 101 antihydrogen atoms has been observed. A measurement of the cross section for {bar H}{sup 0} production is outlined within. The cross section corresponds to the process where a high momentum antiproton causes e{sup +} e{sup -} pair creation near a nucleus with the e{sup +} being captured by the antiproton. Antihydrogen is the first atom made exclusively of antimatter to be detected. The observation experiment's results are the first step towards an antihydrogen spectroscopy experiment which would measure the n = 2 Lamb shift and fine structure.

  3. Efficient transfer of francium atoms

    Science.gov (United States)

    Aubin, Seth; Behr, John; Gorelov, Alexander; Pearson, Matt; Tandecki, Michael; Collister, Robert; Gwinner, Gerald; Shiells, Kyle; Gomez, Eduardo; Orozco, Luis; Zhang, Jiehang; Zhao, Yanting; FrPNC Collaboration

    2016-05-01

    We report on the progress of the FrPNC collaboration towards Parity Non Conservation Measurements (PNC) using francium atoms at the TRIUMF accelerator. We demonstrate efficient transfer (higher than 40%) to the science vacuum chamber where the PNC measurements will be performed. The transfer uses a downward resonant push beam from the high-efficiency capture magneto optical trap (MOT) towards the science chamber where the atoms are recaptured in a second MOT. The transfer is very robust with respect to variations in the parameters (laser power, detuning, alignment, etc.). We accumulate a growing number of atoms at each transfer pulse (limited by the lifetime of the MOT) since the push beam does not eliminate the atoms already trapped in the science MOT. The number of atoms in the science MOT is on track to meet the requirements for competitive PNC measurements when high francium rates (previously demonstrated) are delivered to our apparatus. The catcher/neutralizer for the ion beam has been tested reliably to 100,000 heating/motion cycles. We present initial tests on the direct microwave excitation of the ground hyperfine transition at 45 GHz. Support from NSERC and NRC from Canada, NSF and Fulbright from USA, and CONACYT from Mexico.

  4. Analyzing binding data.

    Science.gov (United States)

    Motulsky, Harvey J; Neubig, Richard R

    2010-07-01

    Measuring the rate and extent of radioligand binding provides information on the number of binding sites, and their affinity and accessibility of these binding sites for various drugs. This unit explains how to design and analyze such experiments.

  5. Analog multivariate counting analyzers

    CERN Document Server

    Nikitin, A V; Armstrong, T P

    2003-01-01

    Characterizing rates of occurrence of various features of a signal is of great importance in numerous types of physical measurements. Such signal features can be defined as certain discrete coincidence events, e.g. crossings of a signal with a given threshold, or occurrence of extrema of a certain amplitude. We describe measuring rates of such events by means of analog multivariate counting analyzers. Given a continuous scalar or multicomponent (vector) input signal, an analog counting analyzer outputs a continuous signal with the instantaneous magnitude equal to the rate of occurrence of certain coincidence events. The analog nature of the proposed analyzers allows us to reformulate many problems of the traditional counting measurements, and cast them in a form which is readily addressed by methods of differential calculus rather than by algebraic or logical means of digital signal processing. Analog counting analyzers can be easily implemented in discrete or integrated electronic circuits, do not suffer fro...

  6. Miniature mass analyzer

    CERN Document Server

    Cuna, C; Lupsa, N; Cuna, S; Tuzson, B

    2003-01-01

    The paper presents the concept of different mass analyzers that were specifically designed as small dimension instruments able to detect with great sensitivity and accuracy the main environmental pollutants. The mass spectrometers are very suited instrument for chemical and isotopic analysis, needed in environmental surveillance. Usually, this is done by sampling the soil, air or water followed by laboratory analysis. To avoid drawbacks caused by sample alteration during the sampling process and transport, the 'in situ' analysis is preferred. Theoretically, any type of mass analyzer can be miniaturized, but some are more appropriate than others. Quadrupole mass filter and trap, magnetic sector, time-of-flight and ion cyclotron mass analyzers can be successfully shrunk, for each of them some performances being sacrificed but we must know which parameters are necessary to be kept unchanged. To satisfy the miniaturization criteria of the analyzer, it is necessary to use asymmetrical geometries, with ion beam obl...

  7. Analyzing Microarray Data.

    Science.gov (United States)

    Hung, Jui-Hung; Weng, Zhiping

    2017-03-01

    Because there is no widely used software for analyzing RNA-seq data that has a graphical user interface, this protocol provides an example of analyzing microarray data using Babelomics. This analysis entails performing quantile normalization and then detecting differentially expressed genes associated with the transgenesis of a human oncogene c-Myc in mice. Finally, hierarchical clustering is performed on the differentially expressed genes using the Cluster program, and the results are visualized using TreeView.

  8. The Atomic orbitals of the topological atom

    OpenAIRE

    Ramos-Cordoba, Eloy; Salvador Sedano, Pedro

    2013-01-01

    The effective atomic orbitals have been realized in the framework of Bader's atoms in molecules theory for a general wavefunction. This formalism can be used to retrieve from any type of calculation a proper set of orthonormalized numerical atomic orbitals, with occupation numbers that sum up to the respective Quantum Theory of Atoms in Molecules (QTAIM) atomic populations. Experience shows that only a limited number of effective atomic orbitals exhibit significant occupation numbers. These c...

  9. Neutral wind results from TIMED Doppler interferometer

    Science.gov (United States)

    Killeen, T.; Gablehouse, R.; Gell, D.; Johnson, R.; Niciejewski, R.; Ortland, D.; Wu, Q.; Skinner, W.; Solomon, S.; Kafkalidis, J.

    2003-04-01

    Since the launch of the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite in December 2001, the TIMED Doppler Interferometer (TIDI) has been collecting lower thermosphere and mesospheric data for over a year. After adjustments to the spectral sampling scheme and operational mode, the instrument has been optimized. Efforts have also been made to improve the instrument performance. Preliminary neutral winds from O2 (0-0) have been analyzed. Tidal features and their seasonal variation are shown clearly in the wind data, which are quantitatively consistent with model prediction. We will report our progress on these efforts.

  10. Detecting magnetically guided atoms with an optical cavity.

    Science.gov (United States)

    Haase, Albrecht; Hessmo, Björn; Schmiedmayer, Jörg

    2006-01-15

    We show that a low-finesse cavity can be efficient for detecting neutral atoms. The low finesse can be compensated for by decreasing the mode waist of the cavity. We have used a near-concentric resonator with a beam waist of 12 microm and a finesse of only 1100 to detect magnetically guided Rb atoms with a detection sensitivity of 0.1 atom in the mode volume. For future experiments on single-atom detection and cavity QED applications, it should be beneficial to use miniaturized optical resonators integrated on atom chips.

  11. Experimental evidence of energetic neutrals production in an ion diode

    Energy Technology Data Exchange (ETDEWEB)

    Pushkarev, A.I., E-mail: aipush@mail.ru; Isakova, Y.I.; Khaylov, I.P.

    2015-01-15

    The paper presents several experimental proofs of the formation of energetic charge-exchange neutrals in a self-magnetically insulated ion diode with a graphite cathode. The energetic neutrals are thought to be produced as a result of charge exchange process between accelerated ions and stationary neutral molecules. The experiments have been carried out using both a diode with externally applied magnetic insulation (single-pulse mode: 100 ns, 250–300 kV) and a diode with self-magnetic insulation (double-pulse mode: 300–500 ns, 100–150 kV (negative pulse); 120 ns, 250–300 kV (positive pulse)). The motivation for looking at the neutral component of the ion beam came when we compared two independent methods to measure the energy density of the beam. A quantitative comparison of infrared measurements with signals from Faraday cups and diode voltage was made to assess the presence of neutral atoms in the ion beam. As another proof of charge-exchange effects in ion diode we present the results of statistical analysis of diode performance. It was found that the shot-to shot variation of the energy density in a set of 50–100 shots does not exceed 11%, whilst the same variation for ion current density was 20–30%; suggesting the presence of neutrals in the beam. Moreover, the pressure in the zone of ion beam energy dissipation exceeds the results stated in cited references. The difference between our experimental data and results stated by other authors we attribute to the presence of a low-energy charge-exchange neutral component in the ion beam.

  12. Solar polar rotation and its effect on heliospheric neutral fluxes

    Science.gov (United States)

    Sokol, J. M.; Grzedzielski, S.; Bzowski, M.

    2016-12-01

    The magnetic field in the solar polar corona exhibit a regular "ray-like" structure associated with large polar coronal holes during solar minimum. The solar rotation twists the magnetic field lines of the expanding fast solar wind over the poles. The twist induces a toroidal component of the polar magnetic field which results in magnetic forces directed towards the rotation axis. That is tantamount to a (weak) zeta pinch, known also in other astrophysical contexts (e.g. AGN plasmas). The pinch compresses the polar solar corona plasma and a cone-like enhancement in the solar wind density forms along the rotation axis. Though the effect is likely very dynamic, a time independent description is used here to get an order-of-magnitude estimate. The weak pinch is treated as a 1st order perturbation to the zero-order radial flow. The obtained density enhancement may affect the near and far heliosphere, modifying the charge-exchange and electron impact ionization rates of neutral atoms in interplanetary space. The charge exchange is the most effective ionization process for hydrogen and oxygen atoms, and electron impact ionization is a significant loss reaction for the helium atoms at close distances to the Sun. The change in the polar density due to the solar polar corona rotation could be of importance in the inner heliosphere for low energy atoms. We will present the influence of this effect on interstellar neutral gas distribution and H ENA fluxes observed by IBEX.

  13. Fabrication of vertically aligned Pd nanowire array in AAO template by electrodeposition using neutral electrolyte

    Directory of Open Access Journals (Sweden)

    Yüzer Hayrettin

    2010-01-01

    Full Text Available Abstract A vertically aligned Pd nanowire array was successfully fabricated on an Au/Ti substrate using an anodic aluminum oxide (AAO template by a direct voltage electrodeposition method at room temperature using diluted neutral electrolyte. The fabrication of Pd nanowires was controlled by analyzing the current–time transient during electrodeposition using potentiostat. The AAO template and the Pd nanowires were characterized by scanning electron microscopy (SEM, energy-dispersive X-ray (EDX methods and X-Ray diffraction (XRD. It was observed that the Pd nanowire array was standing freely on an Au-coated Ti substrate after removing the AAO template in a relatively large area of about 5 cm2, approximately 50 nm in diameter and 2.5 μm in length with a high aspect ratio. The nucleation rate and the number of atoms in the critical nucleus were determined from the analysis of current transients. Pd nuclei density was calculated as 3.55 × 108 cm−2. Usage of diluted neutral electrolyte enables slower growing of Pd nanowires owing to increase in the electrodeposition potential and thus obtained Pd nanowires have higher crystallinity with lower dislocations. In fact, this high crystallinity of Pd nanowires provides them positive effect for sensor performances especially.

  14. Developing QSPR model of gas/particle partition coefficients of neutral poly-/perfluoroalkyl substances

    Science.gov (United States)

    Yuan, Quan; Ma, Guangcai; Xu, Ting; Serge, Bakire; Yu, Haiying; Chen, Jianrong; Lin, Hongjun

    2016-10-01

    Poly-/perfluoroalkyl substances (PFASs) are a class of synthetic fluorinated organic substances that raise increasing concern because of their environmental persistence, bioaccumulation and widespread presence in various environment media and organisms. PFASs can be released into the atmosphere through both direct and indirect sources, and the gas/particle partition coefficient (KP) is an important parameter that helps us to understand their atmospheric behavior. In this study, we developed a temperature-dependent predictive model for log KP of PFASs and analyzed the molecular mechanism that governs their partitioning equilibrium between gas phase and particle phase. All theoretical computation was carried out at B3LYP/6-31G (d, p) level based on neutral molecular structures by Gaussian 09 program package. The regression model has a good statistical performance and robustness. The application domain has also been defined according to OECD guidance. The mechanism analysis shows that electrostatic interaction and dispersion interaction play the most important role in the partitioning equilibrium. The developed model can be used to predict log KP values of neutral fluorotelomer alcohols and perfluor sulfonamides/sulfonamidoethanols with different substitutions at nitrogen atoms, providing basic data for their ecological risk assessment.

  15. HELIOSPHERIC ENERGETIC NEUTRAL HYDROGEN MEASURED WITH ASPERA-3 AND ASPERA-4

    Energy Technology Data Exchange (ETDEWEB)

    Galli, A.; Wurz, P. [Physics Institute, University of Bern, Bern 3012 (Switzerland); Kollmann, P.; Brandt, P. C. [The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723 (United States); Bzowski, M.; Sokół, J. M.; Kubiak, M. A. [Space Research Centre, Polish Academy of Sciences, Warsaw 00-716 (Poland); Grigoriev, A. [Space Research Institute (IKI), Moscow 117997 (Russian Federation); Barabash, S. [The Swedish Institute of Space Physics, Kiruna SE-981 28 (Sweden)

    2013-09-20

    We re-analyze the signal of non-planetary energetic neutral atoms (ENAs) in the 0.4-5.0 keV range measured with the Neutral Particle Detector (NPD) of the ASPERA-3 and ASPERA-4 experiments on board the Mars and Venus Express satellites. Due to improved knowledge of sensor characteristics and exclusion of data sets affected by instrument effects, the typical intensity of the ENA signal obtained by ASPERA-3 is an order of magnitude lower than in earlier reports. The ENA intensities measured with ASPERA-3 and ASPERA-4 now agree with each other. In the present analysis, we also correct the ENA signal for Compton-Getting and for ionization loss processes under the assumption of a heliospheric origin. We find spectral shapes and intensities consistent with those measured by the Interstellar Boundary Explorer (IBEX). The principal advantage of ASPERA with respect to the IBEX sensors is the two times better spectral resolution. In this study, we discuss the physical significance of the spectral shapes and their potential variation across the sky. At present, these observations are the only independent test of the heliospheric ENA signal measured with IBEX in this energy range. The ASPERA measurements also allow us to check for a temporal variation of the heliospheric signal as they were obtained between 2003 and 2007, whereas IBEX has been operational since the end of 2008.

  16. Total organic carbon analyzer

    Science.gov (United States)

    Godec, Richard G.; Kosenka, Paul P.; Smith, Brian D.; Hutte, Richard S.; Webb, Johanna V.; Sauer, Richard L.

    The development and testing of a breadboard version of a highly sensitive total-organic-carbon (TOC) analyzer are reported. Attention is given to the system components including the CO2 sensor, oxidation reactor, acidification module, and the sample-inlet system. Research is reported for an experimental reagentless oxidation reactor, and good results are reported for linearity, sensitivity, and selectivity in the CO2 sensor. The TOC analyzer is developed with gravity-independent components and is designed for minimal additions of chemical reagents. The reagentless oxidation reactor is based on electrolysis and UV photolysis and is shown to be potentially useful. The stability of the breadboard instrument is shown to be good on a day-to-day basis, and the analyzer is capable of 5 sample analyses per day for a period of about 80 days. The instrument can provide accurate TOC and TIC measurements over a concentration range of 20 ppb to 50 ppm C.

  17. Analyzing radioligand binding data.

    Science.gov (United States)

    Motulsky, Harvey; Neubig, Richard

    2002-08-01

    Radioligand binding experiments are easy to perform, and provide useful data in many fields. They can be used to study receptor regulation, discover new drugs by screening for compounds that compete with high affinity for radioligand binding to a particular receptor, investigate receptor localization in different organs or regions using autoradiography, categorize receptor subtypes, and probe mechanisms of receptor signaling, via measurements of agonist binding and its regulation by ions, nucleotides, and other allosteric modulators. This unit reviews the theory of receptor binding and explains how to analyze experimental data. Since binding data are usually best analyzed using nonlinear regression, this unit also explains the principles of curve fitting with nonlinear regression.

  18. Advances in hematology analyzers.

    Science.gov (United States)

    DeNicola, Dennis B

    2011-05-01

    The complete blood count is one of the basic building blocks of the minimum database in veterinary medicine. Over the past 20 years, there has been a tremendous advancement in the technology of hematology analyzers and their availability to the general practitioner. There are 4 basic methodologies that can be used to generate data for a complete blood count: manual methods, quantitative buffy coat analysis, automated impedance analysis, and flow cytometric analysis. This article will review the principles of these methodologies, discuss some of their advantages and disadvantages, and describe some of the hematology analyzers that are available for the in-house veterinary laboratory.

  19. Atom Skimmers and Atom Lasers Utilizing Them

    Science.gov (United States)

    Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

    2005-01-01

    Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

  20. HIV-1 binding and neutralizing antibodies of injecting drug users

    Directory of Open Access Journals (Sweden)

    Ouverney E.P.

    2005-01-01

    Full Text Available Previous studies have demonstrated a stronger seroreactivity against some synthetic peptides responsible for inducing neutralizing antibodies in injecting drug users (IDU compared to that of individuals sexually infected with HIV-1 (S, but the effectiveness in terms of the neutralizing ability of these antibodies has not been evaluated. Our objective was to study the humoral immune response of IDU by determining the specificity of their antibodies and the presence of neutralizing antibodies. The neutralization capacity against the HIV-1 isolate MN (genotype B, the primary HIV-1 isolate 95BRRJ021 (genotype F, and the seroreactivity with peptides known to induce neutralizing antibodies, from the V2 and V3 loops of different HIV-1 subtypes, were analyzed. Seroreactivity indicates that IDU plasma are more likely to recognize a broader range of peptides than S plasma, with significantly higher titers, especially of V3 peptides. Similar neutralization frequencies of the MN isolate were observed in plasma of the IDU (16/47 and S (20/60 groups in the 1:10 dilution. The neutralization of the 95BRRJ021 isolate was more frequently observed for plasma from the S group (15/23 than from the IDU group (15/47, P = 0.0108. No correlation between neutralization and seroreactivity with the peptides tested was observed. These results suggest that an important factor responsible for the extensive and broad humoral immune response observed in IDU is their infection route. There was very little difference in neutralizing antibody response between the IDU and S groups despite their differences in seroreactivity and health status.

  1. Analyzing Stereotypes in Media.

    Science.gov (United States)

    Baker, Jackie

    1996-01-01

    A high school film teacher studied how students recognized messages in film, examining how film education could help students identify and analyze racial and gender stereotypes. Comparison of students' attitudes before and after the film course found that the course was successful in raising students' consciousness. (SM)

  2. Analyzing Workforce Education. Monograph.

    Science.gov (United States)

    Texas Community & Technical Coll. Workforce Education Consortium.

    This monograph examines the issue of task analysis as used in workplace literacy programs, debating the need for it and how to perform it in a rapidly changing environment. Based on experiences of community colleges in Texas, the report analyzes ways that task analysis can be done and how to implement work force education programs more quickly.…

  3. Ultracold atoms and precise time standards.

    Science.gov (United States)

    Campbell, Gretchen K; Phillips, William D

    2011-10-28

    Experimental techniques of laser cooling and trapping, along with other cooling techniques, have produced gaseous samples of atoms so cold that they are, for many practical purposes, in the quantum ground state of their centre-of-mass motion. Such low velocities have virtually eliminated effects such as Doppler shifts, relativistic time dilation and observation-time broadening that previously limited the performance of atomic frequency standards. Today, the best laser-cooled, caesium atomic fountain, microwave frequency standards realize the International System of Units (SI) definition of the second to a relative accuracy of ≈3×10(-16). Optical frequency standards, which do not realize the SI second, have even better performance: cold neutral atoms trapped in optical lattices now yield relative systematic uncertainties of ≈1×10(-16), whereas cold-trapped ions have systematic uncertainties of 9×10(-18). We will discuss the current limitations in the performance of neutral atom atomic frequency standards and prospects for the future.

  4. Neutral hydrogen in galactic fountains

    CERN Document Server

    Booth, C M

    2007-01-01

    Simulations of an isolated Milky Way-like galaxy, in which supernovae power a galactic fountain, reproduce the observed velocity and 21cm brightness statistics of galactic neutral hydrogen (HI). The simulated galaxy consists of a thin HI disk, similar in extent and brightness to that observed in the Milky Way, and extra-planar neutral gas at a range of velocities due to the galactic fountain. Mock observations of the neutral gas resemble the HI flux measurements from the Leiden-Argentine-Bonn (LAB) HI, survey, including a high-velocity tail which matches well with observations of high-velocity clouds. The simulated high-velocity clouds are typically found close to the galactic disk, with a typical line-of-sight distance of 13kpc from observers on the solar circle. The fountain efficiently cycles matter from the centre of the galaxy to its outskirts at a rate of around 0.5 M_sun/yr

  5. Neutral B meson flavor tagging

    Science.gov (United States)

    Wilson, Robert J.

    2001-07-01

    We present an investigation of the use of net charge and kaon identification to tag the flavor of neutral B mesons. The net charge of the neutral B meson decay products is zero if all charged particles are used and slightly non-zero if only undiscriminated hadronic final states are used. The net charge of the kaons alone correctly tags the identity of the neutral meson in at least a third of all decays. We have parametrized the particle identification capability of several techniques, such as dE/dx in time projection chambers, LEP/SLC ring-imaging chambers and an enhanced BaBar DIRC. Using these parametrisations we compare the relative tagging power of each technique to that of an ideal detector.

  6. Neutral B meson flavor tagging

    CERN Document Server

    Wilson, R J

    2001-01-01

    We present an investigation of the use of net charge and kaon identification to tag the flavor of neutral B mesons. The net charge of the neutral B meson decay products is zero if all charged particles are used and slightly non-zero if only undiscriminated hadronic final states are used. The net charge of the kaons alone correctly tags the identity of the neutral meson in at least a third of all decays. We have parametrized the particle identification capability of several techniques, such as dE/dx in time projection chambers, LEP/SLC ring-imaging chambers and an enhanced BaBar DIRC. Using these parametrisations we compare the relative tagging power of each technique to that of an ideal detector. (8 refs).

  7. Inert gas atomization of chemical grade silicon

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, D.; Ferreira Neto, J.B.; Salgado, L.; Nogueira, P.F.; Poco, J.G.R. [Metallurgy Div. Cidade Univ., Inst. for Technological Research, Sao Paulo, SP (Brazil)

    2001-07-01

    The use of inert gas atomization to obtain chemical grade silicon particles was investigated. Both cooling rate and chemical composition are very important regarding a tailored microstructure, related with silicon performance during the synthesis of the silanos, an intermediary raw material in the silicone production. Previously refined silicon was used as raw material. Silicon with different aluminum contents were atomized and analyzed. The atomization temperature was set around 1520 C, and it was used a confined atomization nozzle. It was necessary to use a long atomization chamber to allow the cooling of the coarse silicon particles. After atomization, the powder was characterized and classified. The coarse fraction was milled. Two different particle size groups (different cooling rates) and the as atomized particles were investigated. The chemical behavior during the synthesis of the silanos was analyzed in a laboratory reactor. The relationship between cooling rate, aluminum content and silicon performance during the silanos synthesis is discussed. (orig.)

  8. Two-dimensional array of microtraps with atomic shift register on a chip

    NARCIS (Netherlands)

    Whitlock, S.; Gerritsma, R.; Fernholz, T.; Spreeuw, R.J.C.

    2009-01-01

    Arrays of trapped atoms are the ideal starting points for developing registers comprising large numbers of physical qubits for storing and processing quantum information. One very promising approach involves neutral atom traps produced on microfabricated devices known as atom chips, as almost

  9. Multiple Electron Capture Processes in Slow Collisions of Ar9+ Ions with Na Atoms

    Institute of Scientific and Technical Information of China (English)

    ZhuXiaolong; ShaShan; LiuHuiping; WeiBaoren; MaXinwen; WangZhengling; CaoShiping; QianDongbing; YangZhihu

    2003-01-01

    Slow collisions of highly charged ions with neutral atoms and molecules are of great importance in basic atomic collision physics, Recently, we built a new research facility for atomic physics at the Institute of Modern Physics. We report here the multiple electron transfer processes in collisions of Ar9+ with Na gas target at energy of 180 keV.

  10. Atomic magnetometer

    Science.gov (United States)

    Schwindt, Peter [Albuquerque, NM; Johnson, Cort N [Albuquerque, NM

    2012-07-03

    An atomic magnetometer is disclosed which uses a pump light beam at a D1 or D2 transition of an alkali metal vapor to magnetically polarize the vapor in a heated cell, and a probe light beam at a different D2 or D1 transition to sense the magnetic field via a polarization rotation of the probe light beam. The pump and probe light beams are both directed along substantially the same optical path through an optical waveplate and through the heated cell to an optical filter which blocks the pump light beam while transmitting the probe light beam to one or more photodetectors which generate electrical signals to sense the magnetic field. The optical waveplate functions as a quarter waveplate to circularly polarize the pump light beam, and as a half waveplate to maintain the probe light beam linearly polarized.

  11. PhosphoSiteAnalyzer

    DEFF Research Database (Denmark)

    Bennetzen, Martin V; Cox, Jürgen; Mann, Matthias

    2012-01-01

    an algorithm to retrieve kinase predictions from the public NetworKIN webpage in a semiautomated way and applies hereafter advanced statistics to facilitate a user-tailored in-depth analysis of the phosphoproteomic data sets. The interface of the software provides a high degree of analytical flexibility...... and is designed to be intuitive for most users. PhosphoSiteAnalyzer is a freeware program available at http://phosphosite.sourceforge.net ....

  12. Magnetoresistive emulsion analyzer.

    Science.gov (United States)

    Lin, Gungun; Baraban, Larysa; Han, Luyang; Karnaushenko, Daniil; Makarov, Denys; Cuniberti, Gianaurelio; Schmidt, Oliver G

    2013-01-01

    We realize a magnetoresistive emulsion analyzer capable of detection, multiparametric analysis and sorting of ferrofluid-containing nanoliter-droplets. The operation of the device in a cytometric mode provides high throughput and quantitative information about the dimensions and magnetic content of the emulsion. Our method offers important complementarity to conventional optical approaches involving ferrofluids, and paves the way to the development of novel compact tools for diagnostics and nanomedicine including drug design and screening.

  13. IPv6 Protocol Analyzer

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    With the emerging of next generation Intemet protocol (IPv6), it is expected to replace the current version of Internet protocol (IPv4) that will be exhausted in the near future. Besides providing adequate address space, some other new features are included into the new 128 bits of IP such as IP auto configuration, quality of service, simple routing capability, security, mobility and multicasting. The current protocol analyzer will not be able to handle IPv6 packets. This paper will focus on developing protocol analyzer that decodes IPv6 packet. IPv6 protocol analyzer is an application module,which is able to decode the IPv6 packet and provide detail breakdown of the construction of the packet. It has to understand the detail construction of the IPv6, and provide a high level abstraction of bits and bytes of the IPv6 packet.Thus it increases network administrators' understanding of a network protocol,helps he/she in solving protocol related problem in a IPv6 network environment.

  14. High Atom Number in Microsized Atom Traps

    Science.gov (United States)

    2015-12-14

    Final Performance Report on ONR Grant N00014-12-1-0608 High atom number in microsized atom traps for the period 15 May 2012 through 14 September...TYPE Final Technical Report 3. DATES COVERED (From - To) 05/15/2012-09/14/2012 4. TITLE AND SUBTITLE High atom number in microsized atom traps...forces for implementing a small-footprint, large-number atom -chip instrument. Bichromatic forces rely on absorption and stimulated emission to produce

  15. Computational Mechanistic Study of Redox-Neutral Rh(III)-Catalyzed C-H Activation Reactions of Arylnitrones with Alkynes: Role of Noncovalent Interactions in Controlling Selectivity.

    Science.gov (United States)

    Xing, Yang-Yang; Liu, Jian-Biao; Tian, Ying-Ying; Sun, Chuan-Zhi; Huang, Fang; Chen, De-Zhan

    2016-11-23

    The mechanism of redox-neutral Rh(III)-catalyzed coupling reactions of arylnitrones with alkynes was investigated by density functional theory (DFT) calculations. The free energy profiles associated with the catalytic cycle, involving C(sp(2))-H activation, insertion of alkyne, transfer of O atom, cyclization and protodemetalation, are presented and analyzed. An overwhelming preference for alkyne insertion into Rh-C over Rh-O is observed among all pathways, and the most favorable route is determined. The pivalate-assisted C-H activation step is turnover-limiting, and the cyclization step determines the diastereoselectivity of the reaction, with the stereoselectivity arising mainly from the difference of noncovalent interactions in key transition states. The detailed mechanism of O atom transfer, Rh(III)-Rh(I)-Rh(III) versus Rh(III)-Rh(V)-Rh(III) cycle, is discussed.

  16. A double well interferometer on an atom chip

    DEFF Research Database (Denmark)

    Schumm, Thorsten; Krüger, Peter; Hofferberth, S.

    2006-01-01

    Radio-Frequency coupling between magnetically trapped atomic states allows to create versatile adiabatic dressed state potentials for neutral atom manipulation. Most notably, a single magnetic trap can be split into a double well by controlling amplitude and frequency of an oscillating magnetic...... field. We use this to build an integrated matter wave interferometer on an atom chip. Transverse splitting of quasi one-dimensional Bose-Einstein condensates over a wide range from 3 to 80 μm is demonstrated, accessing the tunnelling regime as well as completely isolated sites. By recombining the two...... the splitting process. RF induced potentials are especially suited for integrated micro manipulation of neutral atoms on atom chips: designing appropriate wire patterns enables control over the created potentials to the (nanometer) precision of the fabrication process. Additionally, hight local RF amplitudes...

  17. Neutral Models with Generalised Speciation

    NARCIS (Netherlands)

    Haegeman, Bart; Etienne, Rampal S.

    Hubbell's neutral theory claims that ecological patterns such as species abundance distributions can be explained by a stochastic model based on simple assumptions. One of these assumptions, the point mutation assumption, states that every individual has the same probability to speciate. Etienne et

  18. HIV-2 neutralization by intact V3-specific Fab fragments

    Directory of Open Access Journals (Sweden)

    Sourial Samer

    2008-08-01

    Full Text Available Abstract The V3 region of both HIV-1 gp120 and HIV-2 gp125 surface glycoprotein has been described as a target for neutralizing antibodies. In this study a conformation-sensitive (3C4 and a linear site-specific (7C8 anti-HIV-2 V3 monoclonal antibody (mAb were characterized. The neutralization capacity of the purified mAbs and their respective papain-generated Fab fragments was analyzed. The Fabs were further characterized by sequence analysis. Our results demonstrate that neither purified mAbs were capable of neutralizing HIV-2, while intact Fab fragments from both mAbs blocked in vitro infection of HIV-2 isolates. Moreover, the conformation sensitive 3C4 Fab neutralized both subtype A and B HIV-2 isolates and SIVsm. Sequence analysis of the hypervariable regions of 3C4 Fab and 7C8 Fab revealed that the third CDR of the heavy chain (CDRH3 of the antibodies was not as long as many of the previously characterized neutralizing antibodies. Our findings suggest that whole 7C8 and 3C4 mAbs are sterically hindered from neutralizing HIV-2, whereas the smaller size of Fab fragments enables access to the V3 region on the virion surface.

  19. Analyzing Chinese Financial Reporting

    Institute of Scientific and Technical Information of China (English)

    SABRINA; ZHANG

    2008-01-01

    If the world’s capital markets could use a harmonized accounting framework it would not be necessary for a comparison between two or more sets of accounting standards. However,there is much to do before this becomes reality.This article aims to pres- ent a general overview of China’s General Accepted Accounting Principles(GAAP), U.S.General Accepted Accounting Principles and International Financial Reporting Standards(IFRS),and to analyze the differ- ences among IFRS,U.S.GAAP and China GAAP using fixed assets as an example.

  20. Mineral/Water Analyzer

    Science.gov (United States)

    1983-01-01

    An x-ray fluorescence spectrometer developed for the Viking Landers by Martin Marietta was modified for geological exploration, water quality monitoring, and aircraft engine maintenance. The aerospace system was highly miniaturized and used very little power. It irradiates the sample causing it to emit x-rays at various energies, then measures the energy levels for sample composition analysis. It was used in oceanographic applications and modified to identify element concentrations in ore samples, on site. The instrument can also analyze the chemical content of water, and detect the sudden development of excessive engine wear.

  1. Analyzing Aeroelasticity in Turbomachines

    Science.gov (United States)

    Reddy, T. S. R.; Srivastava, R.

    2003-01-01

    ASTROP2-LE is a computer program that predicts flutter and forced responses of blades, vanes, and other components of such turbomachines as fans, compressors, and turbines. ASTROP2-LE is based on the ASTROP2 program, developed previously for analysis of stability of turbomachinery components. In developing ASTROP2- LE, ASTROP2 was modified to include a capability for modeling forced responses. The program was also modified to add a capability for analysis of aeroelasticity with mistuning and unsteady aerodynamic solutions from another program, LINFLX2D, that solves the linearized Euler equations of unsteady two-dimensional flow. Using LINFLX2D to calculate unsteady aerodynamic loads, it is possible to analyze effects of transonic flow on flutter and forced response. ASTROP2-LE can be used to analyze subsonic, transonic, and supersonic aerodynamics and structural mistuning for rotors with blades of differing structural properties. It calculates the aerodynamic damping of a blade system operating in airflow so that stability can be assessed. The code also predicts the magnitudes and frequencies of the unsteady aerodynamic forces on the airfoils of a blade row from incoming wakes. This information can be used in high-cycle fatigue analysis to predict the fatigue lives of the blades.

  2. Field Deployable DNA analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, E; Christian, A; Marion, J; Sorensen, K; Arroyo, E; Vrankovich, G; Hara, C; Nguyen, C

    2005-02-09

    This report details the feasibility of a field deployable DNA analyzer. Steps for swabbing cells from surfaces and extracting DNA in an automatable way are presented. Since enzymatic amplification reactions are highly sensitive to environmental contamination, sample preparation is a crucial step to make an autonomous deployable instrument. We perform sample clean up and concentration in a flow through packed bed. For small initial samples, whole genome amplification is performed in the packed bed resulting in enough product for subsequent PCR amplification. In addition to DNA, which can be used to identify a subject, protein is also left behind, the analysis of which can be used to determine exposure to certain substances, such as radionuclides. Our preparative step for DNA analysis left behind the protein complement as a waste stream; we determined to learn if the proteins themselves could be analyzed in a fieldable device. We successfully developed a two-step lateral flow assay for protein analysis and demonstrate a proof of principle assay.

  3. Analyzing the platelet proteome.

    Science.gov (United States)

    García, Angel; Zitzmann, Nicole; Watson, Steve P

    2004-08-01

    During the last 10 years, mass spectrometry (MS) has become a key tool for protein analysis and has underpinned the emerging field of proteomics. Using high-throughput tandem MS/MS following protein separation, it is potentially possible to analyze hundreds to thousands of proteins in a sample at a time. This technology can be used to analyze the protein content (i.e., the proteome) of any cell or tissue and complements the powerful field of genomics. The technology is particularly suitable for platelets because of the absence of a nucleus. Cellular proteins can be separated by either gel-based methods such as two-dimensional gel electrophoresis or one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by liquid chromatography (LC) -MS/MS or by multidimensional LC-MS/MS. Prefractionation techniques, such as subcellular fractionations or immunoprecipitations, can be used to improve the analysis. Each method has particular advantages and disadvantages. Proteomics can be used to compare the proteome of basal and diseased platelets, helping to reveal information on the molecular basis of the disease.

  4. Modeling of neutral gas dynamics in high-density plasmas

    Science.gov (United States)

    Canupp, Patrick Wellington

    This thesis describes a physical model of chemically reactive neutral gas flow and discusses numerical solutions of this model for the flow in an inductively coupled plasma etch reactor. To obtain these solutions, this research develops an efficient, implicit numerical method. As a result of the enhanced numerical stability of the scheme, large time steps advance the solution from initial conditions to a final steady state in fewer iterations and with less computational expense than simpler explicit methods. This method would incorporate suitably as a module in currently existing large scale plasma simulation tools. In order to demonstrate the accuracy of the numerical technique, this thesis presents results from two simulations of flows that possess theoretical solutions. The first case is the inviscid flow of a gas through a converging nozzle. A comparison of the numerical solution to isentropic flow theory shows that the numerical technique capably captures the essential flow features of this environment. The second case is the Couette flow of a gas between two parallel plates. The simulation results compare well with the exact solution for this flow. After establishing the accuracy of the numerical technique, this thesis discusses results for the flow of chemically reactive gases in a chlorine plasma etch reactor. This research examines the influence of the plasma on the neutral gas and the dynamics exhibited by the neutral gas in the reactor. This research finds that the neutral gas temperature strongly depends on the rate at which inelastic, electron-impact dissociation reactions occur and on atomic chlorine wall recombination rates. Additionally, the neutral gas Aow in the reactor includes a significant mass flux of etch product from the wafer surface. Resolution of these effects is useful for neutral gas simulation. Finally, this thesis demonstrates that continuum fluid models provide reasonable accuracy for these low pressure reactor flows due to the fact

  5. Ion-Neutral Collisions in the Interstellar Medium: Wave Damping and Elimination of Collisionless Processes

    Science.gov (United States)

    Spangler, Steven R.; Savage, Allison H.; Redfield, Seth

    2011-09-01

    Most phases of the interstellar medium contain neutral atoms in addition to ions and electrons. This introduces differences in plasma physics processes in those media relative to the solar corona and the solar wind at a heliocentric distance of 1 astronomical unit. In this paper, we consider two well-diagnosed, partially-ionized interstellar plasmas. The first is the Warm Ionized Medium (WIM) which is probably the most extensive phase in terms of volume. The second is the gas of the Local Clouds of the Very Local Interstellar Medium (VLISM). Ion-neutral interactions seem to be important in both media. In the WIM, ion-neutral collisions are relatively rare, but sufficiently frequent to damp magnetohydrodynamic (MHD) waves (as well as propagating MHD eddies) within less than a parsec of the site of generation. This result raises interesting questions about the sources of turbulence in the WIM. In the case of the VLISM, the ion-neutral collision frequency is higher than that in the WIM, because the hydrogen is partially neutral rather than fully ionized. We present results showing that prominent features of coronal and solar wind turbulence seem to be absent in VLISM turbulence. For example, ion temperature does not depend on ion mass. This difference may be due to ion-neutral collisions, which distribute power from more effectively heated massive ions such as iron to other ion species and neutral atoms.

  6. Defect-free atom arrays on demand

    Science.gov (United States)

    Levine, Harry; Bernien, Hannes; Keesling, Alex; Anschuetz, Eric; Senko, Crystal; Vuletic, Vladan; Greiner, Markus; Endres, Manuel; Lukin, Mikhail

    2016-05-01

    Arrays of neutral, trapped atoms have proven to be an extraordinary platform for studying quantum many-body physics and implementing quantum information protocols. Conventional approaches to generate such arrays rely on loading atoms into optical lattices and require elaborate experimental control. An alternative, simpler approach is to load atoms into individual optical tweezers. However, the probabilistic nature of the loading process limits the size of the arrays to small numbers of atoms. Here we present a new method for assembling defect-free arrays of large numbers of atoms. Our technique makes use of an array of tightly focused optical tweezers generated by an acousto-optic deflector. The positions of the traps can be dynamically reconfigured on a sub-millisecond timescale. With single-site resolved fluorescence imaging, we can identify defects in the atom array caused by the probabilistic loading process and rearrange the trap positions in response. This will enable us to generate defect-free atom arrays on demand. We discuss our latest results towards reaching this goal along with schemes to implement long-range interactions between atoms in the array. Now at Caltech.

  7. Diffraction limited optics for single atom manipulation

    CERN Document Server

    Sortais, Y R P; Browaeys, A; Fournet, P; Grangier, P; Lamare, M; Lance, A M; Marion, H; Mercier, R; Messin, G; Tuchendler, C

    2006-01-01

    We present an optical system designed to capture and observe a single neutral atom in an optical dipole trap, created by focussing a laser beam using a large numerical aperture N.A.=0.5 aspheric lens. We experimentally evaluate the performance of the optical system and show that it is diffraction limited over a broad spectral range (~ 200 nm) with a large transverse field (+/- 25 microns). The optical tweezer created at the focal point of the lens is able to trap single atoms of 87Rb and to detect them individually with a large collection efficiency. We measure the oscillation frequency of the atom in the dipole trap, and use this value as an independent determination of the waist of the optical tweezer. Finally, we produce with the same lens two dipole traps separated by 2.2 microns and show that the imaging system can resolve the two atoms.

  8. Crossed, Small-Deflection Energy Analyzer for Wind/Temperature Spectrometer

    Science.gov (United States)

    Herrero, Federico A.; Finne, Theodore T.

    2010-01-01

    Determination of neutral winds and ion drifts in low-Earth-orbit missions requires measurements of the angular and energy distributions of the flux of neutrals and ions entering the satellite from the ram direction. The magnitude and direction of the neutral-wind (or ion-drift) determine the location of the maximum in the angular distribution of the flux. Knowledge of the angle of maximum flux with respect to satellite coordinates (pointing) is essential to determine the wind (or ion-drift) vector. The crossed Small-Deflection Energy Analyzer (SDEA) spectrometer (see Figure 1) occupies minimal volume and consumes minimal power. Designed for upper atmosphere/ionosphere investigations at Earth altitudes above 100 km, the spectrometer operates by detecting the angular and energy distributions of neutral atoms/molecules and ions in two mutually perpendicular planes. In this configuration, the two detection planes actually cross at the spectrometer center. It is possible to merge two SDEAs so they share a common optical axis and alternate measurements between two perpendicular planes, and reduce the number of ion sources from two to one. This minimizes the volume and footprint significantly and reduces the ion source power by a factor of two. The area of the entrance aperture affects the number of ions detected/second and also determines the energy resolution. Thermionic emitters require heater power of about 100 mW to produce 1 mA of electron beam current. Typically, electron energy is about 100 eV and requires a 100-V supply for electron acceleration to supply an additional 100 mW of power. Thus, ion source power is at most 200 mW. If two ion sources were to be used, the ion source power would be, at most, 400 mW. Detector power, deflection voltage power, and microcontroller and other functions require less than 150 mW. A WTS (wind/ temperature spectrometer) with two separate optical axes would consume about 650 mW, while the crossed SDEA described here consumes about

  9. Achieving atomic resolution

    Directory of Open Access Journals (Sweden)

    John Spence

    2002-04-01

    Full Text Available The discovery of the nanotube in 19915 by high resolution electron microscopy (HREM, following closely on the discovery of fullerenes, has initiated a new field of science known as nanoscience. (In fact the fullerene buckyball itself was first observed in 1980, by HREM1. While nanoscience now spans many disciplines, from molecular biology to quantum computing, for all of them, the HREM technique has become the indispensable tool for analyzing the atomic structure of individual bulk nanostructural elements. However this method has long been the technique of choice whenever questions of microstructural characterization arise in materials science.

  10. Imprints from the solar cycle on the helium atom and helium pickup ion distributions

    Directory of Open Access Journals (Sweden)

    D. Rucinski

    Full Text Available Neutral interstellar helium atoms penetrate into the solar system almost unaffected by gas–plasma interactions in the heliospheric interface region, and thus can be considered as carriers of original information on the basic parameters (like density, temperature, bulk velocity of the Very Local Interstellar Medium (VLISM. Such information can nowadays be derived from analysis of data obtained from different experimental methods: in situ measurements of He atoms (Ulysses, observations of the solar backscattered He 584 A radiation (EUVE, in situ measurements of He + pickup ions (AMPTE, Ulysses, Wind, SOHO, ACE. In view of the current coordinated international ISSI campaign devoted to the study of the helium focusing cone structure and its evolution, we analyze expected variations of neutral He density, of He + pickup fluxes and of their phase space distributions at various phases of the solar activity cycle based on a realistic time-dependent modelling of the neutral helium and He + pickup ion distributions, which reflect solar cycle-induced variations of the photoionization rate. We show that the neutral helium density values are generally anticorrelated with the solar activity phase and in extreme cases (near the downwind axis the maximum-to-minimum density ratio may even exceed factors of ~ 3 at 1 AU. We also demonstrate that in the upwind hemisphere (at 1 AU and beyond the He + fluxes are correlated with the solar cycle activity, whereas on the downwind side the maximum of the expected flux up to distances of ~ 3 AU occurs around solar minimum epoch, and only further away does the correlation with solar activity become positive. Finally, we present the response of the phase space distribution spectra of He + pickup ions (in the solar wind frame for different epochs of the solar cycle and heliocentric distances from 1 to 5 AU covering the range of Ulysses, Wind and ACE observations.

    Key words. Solar physics, astrophysics and astronomy

  11. Analyzing business models

    DEFF Research Database (Denmark)

    Nielsen, Christian

    2014-01-01

    , because the costs of processing and analyzing it exceed the benefits indicating bounded rationality. Hutton (2002) concludes that the analyst community’s inability to raise important questions on quality of management and the viability of its business model inevitably led to the Enron debacle. There seems...... financial statement. Plumlee (2003) finds for instance that such information imposes significant costs on even expert users such as analysts and fund managers and reduces their use of it. Analysts’ ability to incorporate complex information in their analyses is a decreasing function of its complexity...... to be evidence of the fact that all types of corporate stakeholders from management to employees, owners, the media and politicians have grave difficulties in interpreting new forms of reporting. One hypothesis could be that if managements’ own understanding of value creation is disclosed to the other...

  12. Analyzing architecture articles

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In the present study, we express the quality, function, and characteristics of architecture to help people comprehensively understand what architecture is. We also reveal the problems and conflict found in population, land, water resources, pollution, energy, and the organization systems in construction. China’s economy is transforming. We should focus on the cities, architectural environment, energy conservation, emission-reduction, and low-carbon output that will result in successful green development. We should macroscopically and microscopically analyze the development, from the natural environment to the artificial environment; from the relationship between human beings and nature to the combination of social ecology in cities, and farmlands. We must learn to develop and control them harmoniously and scientifically to provide a foundation for the methods used in architecture research.

  13. Analyzing geographic clustered response

    Energy Technology Data Exchange (ETDEWEB)

    Merrill, D.W.; Selvin, S.; Mohr, M.S.

    1991-08-01

    In the study of geographic disease clusters, an alternative to traditional methods based on rates is to analyze case locations on a transformed map in which population density is everywhere equal. Although the analyst's task is thereby simplified, the specification of the density equalizing map projection (DEMP) itself is not simple and continues to be the subject of considerable research. Here a new DEMP algorithm is described, which avoids some of the difficulties of earlier approaches. The new algorithm (a) avoids illegal overlapping of transformed polygons; (b) finds the unique solution that minimizes map distortion; (c) provides constant magnification over each map polygon; (d) defines a continuous transformation over the entire map domain; (e) defines an inverse transformation; (f) can accept optional constraints such as fixed boundaries; and (g) can use commercially supported minimization software. Work is continuing to improve computing efficiency and improve the algorithm. 21 refs., 15 figs., 2 tabs.

  14. Exploring potential Pluto-generated neutral tori

    Science.gov (United States)

    Smith, Howard T.; Hill, Matthew; KollMann, Peter; McHutt, Ralph

    2015-11-01

    The NASA New Horizons mission to Pluto is providing unprecedented insight into this mysterious outer solar system body. Escaping molecular nitrogen is of particular interest and possibly analogous to similar features observed at moons of Saturn and Jupiter. Such escaping N2 has the potential of creating molecular nitrogen and N (as a result of molecular dissociation) tori or partial toroidal extended particle distributions. The presence of these features would present the first confirmation of an extended toroidal neutral feature on a planetary scale in our solar system. While escape velocities are anticipated to be lower than those at Enceladus, Io or even Europa, particle lifetimes are much longer in Pluto’s orbit because as a result of much weaker solar interaction processes along Pluto’s orbit (on the order of tens of years). Thus, with a ~248 year orbit, Pluto may in fact be generating an extended toroidal feature along it orbit.For this work, we modify and apply our 3-D Monte Carlo neutral torus model (previously used at Saturn, Jupiter and Mercury) to study/analyze the theoretical possibility and scope of potential Pluto-generated neutral tori. Our model injects weighted particles and tracks their trajectories under the influence of all gravitational fields with interactions with other particles, solar photons and Pluto collisions. We present anticipated N2 and N tori based on current estimates of source characterization and environmental conditions. We also present an analysis of sensitivity to assumed initial conditions. Such results can provide insight into the Pluto system as well as valuable interpretation of New Horizon’s observational data.

  15. PDA: Pooled DNA analyzer

    Directory of Open Access Journals (Sweden)

    Lin Chin-Yu

    2006-04-01

    Full Text Available Abstract Background Association mapping using abundant single nucleotide polymorphisms is a powerful tool for identifying disease susceptibility genes for complex traits and exploring possible genetic diversity. Genotyping large numbers of SNPs individually is performed routinely but is cost prohibitive for large-scale genetic studies. DNA pooling is a reliable and cost-saving alternative genotyping method. However, no software has been developed for complete pooled-DNA analyses, including data standardization, allele frequency estimation, and single/multipoint DNA pooling association tests. This motivated the development of the software, 'PDA' (Pooled DNA Analyzer, to analyze pooled DNA data. Results We develop the software, PDA, for the analysis of pooled-DNA data. PDA is originally implemented with the MATLAB® language, but it can also be executed on a Windows system without installing the MATLAB®. PDA provides estimates of the coefficient of preferential amplification and allele frequency. PDA considers an extended single-point association test, which can compare allele frequencies between two DNA pools constructed under different experimental conditions. Moreover, PDA also provides novel chromosome-wide multipoint association tests based on p-value combinations and a sliding-window concept. This new multipoint testing procedure overcomes a computational bottleneck of conventional haplotype-oriented multipoint methods in DNA pooling analyses and can handle data sets having a large pool size and/or large numbers of polymorphic markers. All of the PDA functions are illustrated in the four bona fide examples. Conclusion PDA is simple to operate and does not require that users have a strong statistical background. The software is available at http://www.ibms.sinica.edu.tw/%7Ecsjfann/first%20flow/pda.htm.

  16. Merit of ground-state electronegativities; a reply to ``Comments on `Introduction to the chemistry of fractionally charged atoms: Electronegativity' ''

    Science.gov (United States)

    Lackner, Klaus S.; Zweig, George

    1987-09-01

    The arguments presented in the Comment by Liebman and Huheey are shown to be incorrect. The operational equivalence of Mulliken ground-state electronegativities and Pauling electronegativities is demonstrated for neutral atoms. It is shown that ground-state electronegativities and valence-state electronegativities for both neutral atoms and ions are also operationally equivalent. A single electronegativity scale based on Mulliken ground-state electronegativities may therefore be used for neutral atoms, ions, and fractionally charged atoms, as originally implied in the paper by Lackner and Zweig.

  17. Instructed neutralization, spontaneous neutralization and prevented neutralization after an obsession-like thought.

    NARCIS (Netherlands)

    M. van den Hout; M. Kindt; T. Weiland; M. Peters

    2002-01-01

    Building on 2 earlier experiments (S. Rachman et al [1996] and M. A. van den Hout [2001]) the present study investigated the effects of neutralizing the consequences of an obsession-like thought in healthy participants. Just like in the earlier studies, writing out and thinking of such a thought gen

  18. Progress on Radiative Transition Probabilities in Neutral Cerium

    Science.gov (United States)

    Curry, J. J.

    2009-10-01

    Cerium is a rare-earth atom that is currently used in energy-efficient metal-halide lamps because of its rich visible emission spectrum. More than 20,000 lines have been observed and classified for neutral cerium in the wavelength range of 340 nm to 1 μm (Bill Martin, unpublished). We recently derived more than 500 absolute transition probabilities from existing experimental data (J. Phys. D: Appl. Phys. 2009). Lawler and Den Hartog at the University of Wisconsin have made measurements that are expected to produce a few thousand transition probabilities. These advances, however, leave the data situation far short of what is needed to simulate an accurate global emission spectrum in numerical models of metal-halide lamps containing cerium. One possibility for closing this gap is through atomic structure calculations. Although it may be difficult for calculations to match the accuracy of measurements for any given transition, the global spectral distribution produced with calculated transition probabilities may still be satisfactory. For such a large number of lines, calculations may be the only realistic way to produce a reasonably complete set of data. We will discuss our recent atomic structure calculations of neutral cerium with the Cowan code based on a parametric fit of calculated energy level values to experimental values.

  19. A new horizon in secondary neutral mass spectrometry: post-ionization using a VUV free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Veryovkin, Igor V.; Calaway, Wallis F.; Moore, Jerry F.; Pellin, Michael J.; Lewellen, John W.; Li, Yuelin; Milton, Stephen V.; King, Bruce V.; Petravic, Mladen

    2004-06-15

    A new time-of-flight (TOF) mass spectrometer incorporating post-ionization of sputtered neutral species with tunable vacuum ultraviolet (VUV) light generated by a free electron laser (FEL) has been developed. Capabilities of this instrument, called SPIRIT, were demonstrated by experiments with photoionization of sputtered neutral gold atoms with 125 nm light generated by the VUV FEL located at Argonne National Laboratory (ANL). In a separate series of experiments with a fixed wavelength VUV light source, a 157 nm F{sub 2} laser, a useful yield (atoms detected per atoms sputtered) of about 12% and a mass resolution better than 1500 were demonstrated for molybdenum.

  20. "Bohr's Atomic Model."

    Science.gov (United States)

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  1. The atomic orbitals of the topological atom.

    Science.gov (United States)

    Ramos-Cordoba, Eloy; Salvador, Pedro; Mayer, István

    2013-06-07

    The effective atomic orbitals have been realized in the framework of Bader's atoms in molecules theory for a general wavefunction. This formalism can be used to retrieve from any type of calculation a proper set of orthonormalized numerical atomic orbitals, with occupation numbers that sum up to the respective Quantum Theory of Atoms in Molecules (QTAIM) atomic populations. Experience shows that only a limited number of effective atomic orbitals exhibit significant occupation numbers. These correspond to atomic hybrids that closely resemble the core and valence shells of the atom. The occupation numbers of the remaining effective orbitals are almost negligible, except for atoms with hypervalent character. In addition, the molecular orbitals of a calculation can be exactly expressed as a linear combination of this orthonormalized set of numerical atomic orbitals, and the Mulliken population analysis carried out on this basis set exactly reproduces the original QTAIM atomic populations of the atoms. Approximate expansion of the molecular orbitals over a much reduced set of orthogonal atomic basis functions can also be accomplished to a very good accuracy with a singular value decomposition procedure.

  2. Atomic tests of symmetry principles

    Energy Technology Data Exchange (ETDEWEB)

    Davies, I.O.G.

    1986-01-01

    Parity non-conserving effects in atoms due to the neutral weak current interaction can be enhanced in two ways: by exploiting the Z-dependence and by using a near degeneracy between opposite parity states. In this thesis a case where both enhancements are simultaneously present is considered: samarium has Z = 62 and the states 4f{sup 6}6s6p {sup 7}G{sub 1}{sup 0} and 4f{sup 6}6d5d {sup 7}F{sub 1} are only 320 GHz apart. A calculation by Gongora and Sandars (1986) yields a value for R = Im {sup PNC}/ of 10{sup {minus}4}. To assess the feasibility of utilizing this gain to detect PNC effects a number of exploratory experiments have been performed and a new type of optical rotation experiment, involving crossed electric and magnetic fields,has been considered. Results are presented for the E1 transition 4f{sup 6}6s{sup 2} {sup 7}F{sub 0} - 4f{sup 6}6s6p {sup 7}G{sub 1} at 639 nm which include analyses of the absorption spectrum (both Doppler-broadened and Doppler-free), the Faraday and the Stark induced rotation. The data include measurements of isotope shifts and hyperfine structure constants, the oscillator strength (from the deduced natural linewidth) and the broadening constant for the He-Sm system. The Stark rotation was analyzed giving {vert bar}4f{sup 6}6s5d {sup 7}F{sub 1}{parallel}er{parallel}4f{sup 6}6s6p {sup 7}G{sub 1}{vert bar} = 0.85 (5) e a{sub 0}. The M1 resonance was located by Stark mixing and the background Faraday rotation in this region investigated. It is concluded that because of observed background, the low E1 transition amplitude measured and the low work function of samarium making the application of high electrical fields in the oven difficult that a PNC optical rotation experiment is unlikely to offer any advantage over existing experiments.

  3. Fundamental sputtering studies: Nonresonant ionization of sputtered neutrals

    Energy Technology Data Exchange (ETDEWEB)

    Burnett, J.W.; Pellin, M.J.; Calaway, W.F.; Gruen, D.M. (Argonne National Lab., IL (United States)); Yates, J.T. Jr. (Pittsburgh Univ., PA (United States). Dept. of Chemistry)

    1989-01-04

    Because of the practical importance of sputtering, numerous theories and computer simulations are used for predicting many aspects of the sputtering process. Unfortunately, many of the calculated sputtering results are untested by experiment. Until recently, most sputtering experiments required either very high ion fluences or the detection of only minor constituents of the sputtered flux, i.e., ions. These techniques may miss the subtleties involved in the sputtering process. High-detection-efficiency mass spectrometry, coupled with the laser ionization of neutral atoms, allows the detection of the major sputtered species with very low incident ion fluences. The depth-of-origin of sputtered atoms is one example of an important but poorly understood aspect of the sputtering process. By following the sputtering yield of a substrate atom with various coverages of an adsorbed overlayer, the depth of origin of sputtered atoms has been determined. Our results indicate that two-thirds of the sputtered flux originates in the topmost atomic layer. The ion-dose dependence of sputtering yields has long been assumed to be quite minor for low- to-moderate primary ion fluences. We have observed a two-fold decrease in the sputtering yield of the Ru(0001) surface for very low primary ion fluences. Data analysis results in a cross section for damage of 2.7 {plus minus} 1.0 {times} 10{sup {minus}15}cm{sup 2}. 40 refs., 3 figs., 2 tabs.

  4. Spontaneous decay of an atom excited in a dense and disordered atomic ensemble: quantum microscopic approach

    CERN Document Server

    Kuraptsev, A S

    2016-01-01

    On the basis of general theoretical results developed previously in [I. M. Sokolov et al., J. Exp. Theor. Phys. 112, 246 (2011)], we analyze spontaneous decay of a single atom inside cold atomic clouds under conditions when the averaged interatomic separation is less or comparable with the wavelength of quasi resonant radiation. Beyond the decay dynamics we analyze shifts of resonance as well as distortion of the spectral shape of the atomic transition.

  5. Atom capture by nanotube and scaling anomaly

    CERN Document Server

    Giri, Pulak Ranjan

    2007-01-01

    The existence of bound state of the polarizable neutral atom in the inverse square potential created by the electric field of single walled charged carbon nanotube (SWNT) is shown to be theoretically possible. The consideration of inequivalent boundary conditions due to self-adjoint extensions lead to this nontrivial bound state solution. It is also shown that the scaling anomaly is responsible for the existence of bound state. Binding of the polarizable atoms in the coupling constant interval \\eta^2\\in[0,1) may be responsible for the smearing of the edge of steps in quantized conductance, which has not been considered so far in literature.

  6. Laser Cooled Atomic Clocks in Space

    Science.gov (United States)

    Thompson, R. J.; Kohel, J.; Klipstein, W. M.; Seidel, D. J.; Maleki, L.

    2000-01-01

    The goals of the Glovebox Laser-cooled Atomic Clock Experiment (GLACE) are: (1) first utilization of tunable, frequency-stabilized lasers in space, (2) demonstrate laser cooling and trapping in microgravity, (3) demonstrate longest 'perturbation-free' interaction time for a precision measurement on neutral atoms, (4) Resolve Ramsey fringes 2-10 times narrower than achievable on Earth. The approach taken is: the use of COTS components, and the utilization of prototype hardware from LCAP flight definition experiments. The launch date is scheduled for Oct. 2002. The Microgravity Science Glovebox (MSG) specifications are reviewed, and a picture of the MSG is shown.

  7. INFERNO - A better model of atoms in dense plasmas

    Science.gov (United States)

    Liberman, D. A.

    1982-03-01

    A self-consistent field model of atoms in dense plasmas has been devised and incorporated in a computer program. In the model there is a uniform positive charge distribution with a hole in it and at the center of the hole an atomic nucleus. There are electrons, in both bound and continuum states, in sufficient number to form an electrically neutral system. The Dirac equation is used so that high Z atoms can be dealt with. A finite temperature is assumed, and a mean field (average atom) approximation is used in statistical averages. Applications have been made to equations of states and to photoabsorption.

  8. Cold atom-ion experiments in hybrid traps

    CERN Document Server

    Härter, Arne

    2013-01-01

    In the last 5 years, a novel field of physics and chemistry has developed in which cold trapped ions and ultracold atomic gases are brought into contact with each other. Combining ion traps with traps for neutral atoms yields a variety of new possibilities for research and experiments. These range from studies of cold atom-ion collisions and atom-ion chemistry to applications in quantum information science and condensed matter related research. In this article we give a brief introduction into this new field and describe some of the perspectives for its future development.

  9. Analytical evaluation of atomic form factors: application to Rayleigh scattering

    CERN Document Server

    Safari, L; Amaro, P; Jänkälä, K; Fratini, F

    2014-01-01

    Atomic form factors are widely used for the characterization of targets and specimens, from crystallography to biology. By using recent mathematical results, here we derive an analytical expression for the atomic form factor within the independent particle model constructed from nonrelativistic screened hydrogenic wavefunctions. The range of validity of this analytical expression is checked by comparing the analytically obtained form factors with the ones obtained within the Hartee-Fock method. As an example, we apply our analytical expression for the atomic form factor to evaluate the differential cross section for Rayleigh scattering off neutral atoms.

  10. Magnetically Guiding Atoms with Current-Carrying Conductors

    Institute of Scientific and Technical Information of China (English)

    刘南春; 高伟建; 印建平

    2002-01-01

    We propose a novel magnetic guide for cold neutral atoms using some current-carrying conductors. The spatial distributions of the magnetic fields from a V-shaped or U-shaped current-carrying conductor are calculated, and the relationship between the resulting magnetic field and the parameters of the current-carrying conductors is analysed in detail. The result shows that these current-carrying conductors can be used to realize a single or a controllable double magnetic guide of cold atoms in the weak-field-seeking state, and to construct various atom-optical elements, and even to realize a single-mode atomic waveguiding under certain conditions.

  11. Detecting magnetically guided atoms with an optical cavity

    OpenAIRE

    Haase, Albrecht; Hessmo, Björn; Schmiedmayer, Jörg

    2005-01-01

    We show that a low finesse cavity can be efficient for detecting neutral atoms. The low finesse can be compensated for by decreasing the mode waist of the cavity. We have used a near concentric resonator with a beam waist of 12$\\mu$m and a finesse of only 1100 to detect magnetically guided Rb atoms with a detection sensitivity of 0.1 atom in the mode volume. For future experiments on single atom detection and cavity QED applications, it should be very beneficial to use miniaturized optical re...

  12. Oxidation mechanism of Penicillium digitatum spores through neutral oxygen radicals

    Science.gov (United States)

    Hashizume, Hiroshi; Ohta, Takayuki; Takeda, Keigo; Ishikawa, Kenji; Hori, Masaru; Ito, Masafumi

    2014-01-01

    To investigate the inactivation process of Penicillium digitatum spores through neutral oxygen species, the spores were treated with an atmospheric-pressure oxygen radical source and observed in-situ using a fluorescent confocal-laser microscope. The treated spores were stained with two fluorescent dyes, 1,1‧-dioctadecyl-3,3,Y,3‧-tetramethylindocarbocyanine perchlorate (DiI) and diphenyl-1-pyrenylphosphine (DPPP). The intracellular organelles as well as the cell membranes in the spores treated with the oxygen radical source were stained with DiI without a major morphological change of the membranes. DPPP staining revealed that the organelles were oxidized by the oxygen radical treatment. These results suggest that neutral oxygen species, especially atomic oxygen, induce a minor structural change or functional inhibition of cell membranes, which leads to the oxidation of the intracellular organelles through the penetration of reactive oxygen species into the cell.

  13. Millimeter Wave Scattering from Neutral and Charged Water Droplets

    CERN Document Server

    Heifetz, Alexander; Liao, Shaolin; Gopalsami, N Sami; Raptis, A C Paul

    2010-01-01

    We investigated 94GHz millimeter wave (MMW) scattering from neutral and charged water mist produced in the laboratory with an ultrasonic atomizer. Diffusion charging of the mist was accomplished with a negative ion generator (NIG). We observed increased forward and backscattering of MMW from charged mist, as compared to MMW scattering from an uncharged mist. In order to interpret the experimental results, we developed a model based on classical electrodynamics theory of scattering from a dielectric sphere with diffusion-deposited mobile surface charge. In this approach, scattering and extinction cross-sections are calculated for a charged Rayleigh particle with effective dielectric constant consisting of the volume dielectric function of the neutral sphere and surface dielectric function due to the oscillation of the surface charge in the presence of applied electric field. For small droplets with (radius smaller than 100nm), this model predicts increased MMW scattering from charged mist, which is qualitative...

  14. Bios data analyzer.

    Science.gov (United States)

    Sabelli, H; Sugerman, A; Kovacevic, L; Kauffman, L; Carlson-Sabelli, L; Patel, M; Konecki, J

    2005-10-01

    The Bios Data Analyzer (BDA) is a set of computer programs (CD-ROM, in Sabelli et al., Bios. A Study of Creation, 2005) for new time series analyses that detects and measures creative phenomena, namely diversification, novelty, complexes, nonrandom complexity. We define a process as creative when its time series displays these properties. They are found in heartbeat interval series, the exemplar of bios .just as turbulence is the exemplar of chaos, in many other empirical series (galactic distributions, meteorological, economic and physiological series), in biotic series generated mathematically by the bipolar feedback, and in stochastic noise, but not in chaotic attractors. Differencing, consecutive recurrence and partial autocorrelation indicate nonrandom causation, thereby distinguishing chaos and bios from random and random walk. Embedding plots distinguish causal creative processes (e.g. bios) that include both simple and complex components of variation from stochastic processes (e.g. Brownian noise) that include only complex components, and from chaotic processes that decay from order to randomness as the number of dimensions is increased. Varying bin and dimensionality show that entropy measures symmetry and variety, and that complexity is associated with asymmetry. Trigonometric transformations measure coexisting opposites in time series and demonstrate bipolar, partial, and uncorrelated opposites in empirical processes and bios, supporting the hypothesis that bios is generated by bipolar feedback, a concept which is at variance with standard concepts of polar and complementary opposites.

  15. TEAMS Model Analyzer

    Science.gov (United States)

    Tijidjian, Raffi P.

    2010-01-01

    The TEAMS model analyzer is a supporting tool developed to work with models created with TEAMS (Testability, Engineering, and Maintenance System), which was developed by QSI. In an effort to reduce the time spent in the manual process that each TEAMS modeler must perform in the preparation of reporting for model reviews, a new tool has been developed as an aid to models developed in TEAMS. The software allows for the viewing, reporting, and checking of TEAMS models that are checked into the TEAMS model database. The software allows the user to selectively model in a hierarchical tree outline view that displays the components, failure modes, and ports. The reporting features allow the user to quickly gather statistics about the model, and generate an input/output report pertaining to all of the components. Rules can be automatically validated against the model, with a report generated containing resulting inconsistencies. In addition to reducing manual effort, this software also provides an automated process framework for the Verification and Validation (V&V) effort that will follow development of these models. The aid of such an automated tool would have a significant impact on the V&V process.

  16. Analyzing Teachers' Stories

    Directory of Open Access Journals (Sweden)

    Anat Kainan

    2002-09-01

    Full Text Available This article presents an integrated socio-literal approach as a way to analyze work stories. It uses a case of teachers' stories about the administration as an example. The stories focus on grumbles about various activities of members of the management of a school in a small town. The complaints appear in descriptions of the action, the characters, and, in particular, in the way the story is presented to the audience. The stories present a situation of two opposing groups-the administration and the teachers. The presentation of the stories creates a sense of togetherness among the veterans and new teachers in the staff room, and helps the integration of the new teachers into the staff. The veterans use the stories as an opportunity to express their anger at not having been assigned responsibilities on the one hand and their hopes of such promotion on the other. The stories act as a convenient medium to express criticism without entering into open hostilities. Behind them, a common principle can be discerned- the good of the school. The stories describe the infringement of various aspects of the school's social order, and it is possible to elicit from them what general pattern the teachers want to preserve in the school.

  17. Downhole Fluid Analyzer Development

    Energy Technology Data Exchange (ETDEWEB)

    Bill Turner

    2006-11-28

    A novel fiber optic downhole fluid analyzer has been developed for operation in production wells. This device will allow real-time determination of the oil, gas and water fractions of fluids from different zones in a multizone or multilateral completion environment. The device uses near infrared spectroscopy and induced fluorescence measurement to unambiguously determine the oil, water and gas concentrations at all but the highest water cuts. The only downhole components of the system are the fiber optic cable and windows. All of the active components--light sources, sensors, detection electronics and software--will be located at the surface, and will be able to operate multiple downhole probes. Laboratory testing has demonstrated that the sensor can accurately determine oil, water and gas fractions with a less than 5 percent standard error. Once installed in an intelligent completion, this sensor will give the operating company timely information about the fluids arising from various zones or multilaterals in a complex completion pattern, allowing informed decisions to be made on controlling production. The research and development tasks are discussed along with a market analysis.

  18. Analyzing Spacecraft Telecommunication Systems

    Science.gov (United States)

    Kordon, Mark; Hanks, David; Gladden, Roy; Wood, Eric

    2004-01-01

    Multi-Mission Telecom Analysis Tool (MMTAT) is a C-language computer program for analyzing proposed spacecraft telecommunication systems. MMTAT utilizes parameterized input and computational models that can be run on standard desktop computers to perform fast and accurate analyses of telecommunication links. MMTAT is easy to use and can easily be integrated with other software applications and run as part of almost any computational simulation. It is distributed as either a stand-alone application program with a graphical user interface or a linkable library with a well-defined set of application programming interface (API) calls. As a stand-alone program, MMTAT provides both textual and graphical output. The graphs make it possible to understand, quickly and easily, how telecommunication performance varies with variations in input parameters. A delimited text file that can be read by any spreadsheet program is generated at the end of each run. The API in the linkable-library form of MMTAT enables the user to control simulation software and to change parameters during a simulation run. Results can be retrieved either at the end of a run or by use of a function call at any time step.

  19. Rocket Experiment For Neutral Upwelling

    Science.gov (United States)

    Kenward, D. R.; Lessard, M.

    2015-12-01

    Observations from the CHAMP satellite from 2004 show relatively small scale heating in the thermosphere. Several different mechanisms have been proposed to explain this phenomenon. The RENU 2 rocket mission includes a suite of 14 instruments which will acquire data to help understand processes involved in neutral upwelling in the cusp. Neutral, ion, and electron measurements will be made to provide an assessment of the upwelling process. SUPERDarn measurements of large- scale Joule heating in the cusp during overflight will also be acquired. Small-scale data which could possibly be associated with Alfvén waves, will be acquired using onboard electric field measurements. In-situ measurement of precipitating electrons and all other measurements will be used in thermodynamic and electrodynamic models for comparison to the observed upwelling.

  20. Optical Neutrality: Invisibility without Cloaking

    CERN Document Server

    Hodges, Reed; Durach, Maxim

    2016-01-01

    We show that it is possible to design an invisible wavelength-sized metal-dielectric metamaterial object without evoking cloaking. Our approach is an extension of the neutral inclusion concept by Zhou and Hu [Phys.Rev.E 74, 026607 (2006)] to Mie scatterers. We demonstrate that an increase of metal fraction in the metamaterial leads to a transition from dielectric-like to metal-like scattering, which proceeds through invisibility or optical neutrality of the scatterer. Formally this is due to cancellation of multiple scattering orders, similarly to plasmonic cloaking introduced by Alu and Engheta [Phys.Rev.E 72, 016623 (2005)], but without introduction of the separation of the scatterer into cloak and hidden regions.