WorldWideScience

Sample records for atomic beams

  1. Polarized atomic hydrogen beam

    Energy Technology Data Exchange (ETDEWEB)

    Chan, N.; Crowe, D.M.; Lubell, M.S.; Tang, F.C.; Vasilakis, A.; Mulligan, F.J.; Slevin, J.

    1988-12-01

    We describe the design and operating characteristics of a simple polarized atomic hydrogen beam particularly suitable for applications to crossed beams experiments. In addition to experimental measurements, we present the results of detailed computer models, using Monte-Carlo ray tracing techniques, optical analogs, and phase-space methods, that not only provide us with a confirmation of our measurement, but also allow us to characterize the density, polarization, and atomic fraction of the beam at all points along its path. As a subsidiary result, we also present measurements of the relative and absolute efficiencies of the V/G Supavac mass analyzer for masses 1 and 2.

  2. Polarized atomic beams for targets

    International Nuclear Information System (INIS)

    The basic principle of the production of polarized atomic hydrogen and deuterium beams are reviewed. The status of the present available polarization, density and intensity are presented. The improvement of atomic beam density by cooling the hydrogen atoms to low velocity is discussed. The possible use of polarized atomic beams as targets in storage rings is shown. It is proposed that polarized atomic beams can be used to produce polarized gas targets with high polarization and greatly improved density

  3. Stable atomic hydrogen: Polarized atomic beam source

    International Nuclear Information System (INIS)

    We have carried out experiments with stable atomic hydrogen with a view to possible applications in polarized targets or polarized atomic beam sources. Recent results from the stabilization apparatus are described. The first stable atomic hydrogen beam source based on the microwave extraction method (which is being tested ) is presented. The effect of the stabilized hydrogen gas density on the properties of the source is discussed. (orig.)

  4. Single beam atom sorting machine

    International Nuclear Information System (INIS)

    We create two overlapping one-dimensional optical lattices using a single laser beam, a spatial light modulator and a high numerical aperture lens. These lattices have the potential to trap single atoms, and using the dynamic capabilities of the spatial light modulator may shift and sort atoms to a minimum atom-atom separation of 1.52 μm. We show how a simple feedback circuit can compensate for the spatial light modulator's intensity modulation

  5. A polarized atomic hydrogen beam

    OpenAIRE

    Chan, N; Crowe, D.M.; Lubell, M. S.; Tang, F.C.; Vasilakis, A.; Mulligan, F. J.; Slevin, J.

    1988-01-01

    We describe the design and operating characteristics of a simple polarized atomic hydrogen beam particularly suitable for applications to crossed beams experiments. In addition to experimental measurements, we present the results of detailed computer models, using Monte-Carlo ray tracing techniques, optical analogs, and phase-space methods, that not only provide us with a confirmation of our measurement, but also allow us to characterize the density, polarization, and atomic fraction of the b...

  6. A polarized atomic hydrogen beam

    International Nuclear Information System (INIS)

    We describe the design and operating characteristics of a simple polarized atomic hydrogen beam particularly suitable for applications to crossed beams experiments. In addition to experimental measurements, we present the results of detailed computer models, using Monte-Carlo ray tracing techniques, optical analogs, and phase-space methods, that not only provide us with a confirmation of our measurement, but also allow us to characterize the density, polarization, and atomic fraction of the beam at all points along its path. As a subsidiary result, we also present measurements of the relative and absolute efficiencies of the V/G Supavac mass analyzer for masses 1 and 2. (orig.)

  7. Atomic and molecular beams production and collimation

    CERN Document Server

    Lucas, Cyril Bernard

    2013-01-01

    Atomic and molecular beams are employed in physics and chemistry experiments and, to a lesser extent, in the biological sciences. These beams enable atoms to be studied under collision-free conditions and allow the study of their interaction with other atoms, charged particles, radiation, and surfaces. Atomic and Molecular Beams: Production and Collimation explores the latest techniques for producing a beam from any substance as well as from the dissociation of hydrogen, oxygen, nitrogen, and the halogens.The book not only provides the basic expressions essential to beam design but also offers

  8. Imaging an atomic beam using fluorescence

    Institute of Scientific and Technical Information of China (English)

    Ming He(何明); Jin Wang(王谨); Mingsheng Zhan(詹明生)

    2003-01-01

    A fluorescence detection scheme is applied to image an atomic beam. Using two laser diodes as the sources of detection light and pumping light respectively, the fluorescence image of the atomic beam is then observed by a commercial CCD-camera, which is corresponding to the atomic state and velocity distribution. The detection scheme has a great utilization in the experiments of cold atoms and atomic optics.

  9. A cold 87Rb atomic beam

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Jia; Feng Yan-Ying; Xue Hong-Bo; Zhou Zhao-Ying; Zhang Wen-Dong

    2011-01-01

    We demonstrate an experimental setup for the production of a beam source of cold 87Rb atoms.The atoms are extracted from a trapped cold atomic cloud in an unbalanced three-dimensional magneto-optical trap.Via a radiation pressure difference generated by a specially designed leak tunnel along one trapping laser beam,the atoms are pushed out continuously with low velocities and a high flux.The most-probable velocity in the beam is varied from 9 m/s to 19 m/s by varying the detuning of the trapping laser beams in the magneto-optical trap and the flux can be tuned up to 4× 109 s-1 by increasing the intensity of the trapping beams.We also present a simple model for describing the dependence of the beam performance on the magneto-optical trap trapping laser intensity and the detuning.

  10. Theoretical tools for atom laser beam propagation

    OpenAIRE

    Riou, J. -F.; Coq, Y. Le; Impens, F; Guerin, W.; Bordé, C. J.; Aspect, A; Bouyer, P.

    2008-01-01

    We present a theoretical model for the propagation of non self-interacting atom laser beams. We start from a general propagation integral equation, and we use the same approximations as in photon optics to derive tools to calculate the atom laser beam propagation. We discuss the approximations that allow to reduce the general equation whether to a Fresnel-Kirchhoff integral calculated by using the stationary phase method, or to the eikonal. Within the paraxial approximation, we also introduce...

  11. Radio frequency atomic hydrogen beam source

    International Nuclear Information System (INIS)

    A simple, convenient rf discharge source for the production of an intense beam of hydrogen atoms is described. The design and operation is such that the discharge tube can be operated over a period of several thousand hours, producing an intense beam with dissociation approx.95%

  12. Atomic oxygen beam source for erosion simulation

    Science.gov (United States)

    Cuthbertson, J. W.; Langer, W. D.; Motley, R. W.

    1990-01-01

    A device for production of low-energy (5-10 eV) neutral atomic beams for surface modification studies, which recreates the flux of atomic oxygen in LEO, is described. The beam is produced by acceleration of plasma ions onto a negatively biased plate of high-Z metal; the ions are neutralized and reflected by the surface, retaining a large fraction of their incident kinetic energy, forming a beam of atoms. The device is based on a magnetically confined (3-4 kG) coaxial plasma source and the atom energy can be varied by adjusting the bias voltage. The source provides a neutral flux of roughly 5 x 10 to the 16th/sq cm/s at a distance of 10 cm and a fluence of roughly 10 to the 21st/sq cm in five hours. The source has been characterized with plasma diagnostics and by measuring the energy of an atomic argon beam using a mass spectrometer. Samples of carbon film, carbon-based paint, Kapton, Mylar, and Teflon exposed to atomic O beams show erosion quite similar to those observed in orbit on the Space Shuttle.

  13. A continuous cold atomic beam interferometer

    International Nuclear Information System (INIS)

    We demonstrate an atom interferometer that uses a laser-cooled continuous beam of 87Rb atoms having velocities of 10–20 m/s. With spatially separated Raman beams to coherently manipulate the atomic wave packets, Mach–Zehnder interference fringes are observed at an interference distance of 2L = 19 mm. The apparatus operates within a small enclosed area of 0.07 mm2 at a bandwidth of 190 Hz with a deduced sensitivity of 7.8×10−5 rad/s/√(Hz) for rotations. Using a low-velocity continuous atomic source in an atom interferometer enables high sampling rates and bandwidths without sacrificing sensitivity and compactness, which are important for applications in real dynamic environments

  14. Atom diffraction with a 'natural' metastable atom nozzle beam

    Science.gov (United States)

    Karam, J.-C.; Wipf, N.; Grucker, J.; Perales, F.; Boustimi, M.; Vassilev, G.; Bocvarski, V.; Mainos, C.; Baudon, J.; Robert, J.

    2005-08-01

    The resonant metastability-exchange process is used to obtain a metastable atom beam with intrinsic properties close to those of a ground-state atom nozzle beam (small angular aperture, narrow velocity distribution). The estimated effective source diameter (15 µm) is small enough to provide at a distance of 597 mm a transverse coherence radius of about 873 nm for argon, 1236 nm for neon and 1660 nm for helium. It is demonstrated both by experiment and numerical calculations with He*, Ne* and Ar* metastable atoms, that this beam gives rise to diffraction effects on the transmitted angular pattern of a silicon-nitride nano-slit grating (period 100 nm). Observed patterns are in good agreement with previous measurements with He* and Ne* metastable atoms. For argon, a calculation taking into account the angular aperture of the beam (0.35 mrad) and the effect of the van der Waals interaction—the van der Waals constant C3 = 1.83+0.1-0.15 au being derived from spectroscopic data—leads to a good agreement with experiment.

  15. Light forces on an indium atomic beam

    International Nuclear Information System (INIS)

    In this thesis it was studied, whether indium is a possible candidate for the nanostructuration respectively atomic lithography. For this known method for the generation and stabilization of the light necessary for the laser cooling had to be fitted to the special properties of indium. The spectroscopy of indium with the 451 nm and the 410 nm light yielded first hints that the formulae for the atom-light interaction for a two-level atom cannot be directly transferred to the indium atom. By means of the obtained parameters of the present experiment predictions for a possible Doppler cooling of the indium atomic beam were calculated. Furthermore the possibility for the direct deposition of indium on a substrate was studied

  16. A new atomic beam source: The ''candlestick''

    Science.gov (United States)

    Hau, Lene Vestergaard; Golovchenko, J. A.; Burns, Michael M.

    1994-12-01

    The design of a novel-type of atomic beam source which provides for long term, stable operation at high emission rates is reported. The heart of the design is the ``candlestick'' where liquid source material is transported by capillary action to a localized hot emission region. A surrounding cavity kept at the melting point for the source material shields the vacuum chamber walls from this region. The atomic beam escaping from the source is collimated, and uncollimated atoms are transported back to the liquid reservoir at the bottom of the ``candlestick'' by capillary action. This design has advantages over traditional oven designs: localized heating provides for large emission rates under high vacuum conditions, collimation is combined with recycling and conservation of source material, and the use of capillarity allows any orientation of the beam source. The source has been tested with sodium, and we believe that the design is useful for a broad range of applications including thin-film evaporation, molecular beam epitaxy, and semiconductor surface doping. With the low thermal mass of the emission section, the source could be optimized for pulsed mode operation. Furthermore, it is anticipated that the design ideas presented here could form the basis for a supersonic source with very high Mach numbers.

  17. Single structured light beam as an atomic cloud splitter

    International Nuclear Information System (INIS)

    We propose a scheme to split a cloud of cold noninteracting neutral atoms based on their dipole interaction with a single structured light beam which exhibits parabolic cylindrical symmetry. Using semiclassical numerical simulations, we establish a direct relationship between the general properties of the light beam and the relevant geometric and kinematic properties acquired by the atomic cloud as it passes through the beam.

  18. Wave mechanics of a two-wire atomic beam splitter

    International Nuclear Information System (INIS)

    We consider the problem of an atomic beam propagating quantum mechanically through an atom beam splitter. Casting the problem in an adiabatic representation (in the spirit of the Born-Oppenheimer approximation in molecular physics) sheds light on explicit effects due to nonadiabatic passage of the atoms through the splitter region. We are thus able to probe the fully three-dimensional structure of the beam splitter, gathering quantitative information about mode mixing, splitting ratios, and reflection and transmission probabilities

  19. Measuring the quantum statistics of an atom laser beam

    OpenAIRE

    Bradley, A. S.; Olsen, M. K.; Haine, S. A.; Hope, J. J.

    2006-01-01

    We propose and analyse a scheme for measuring the quadrature statistics of an atom laser beam using extant optical homodyning and Raman atom laser techniques. Reversal of the normal Raman atom laser outcoupling scheme is used to map the quantum statistics of an incoupled beam to an optical probe beam. A multimode model of the spatial propagation dynamics shows that the Raman incoupler gives a clear signal of de Broglie wave quadrature squeezing for both pulsed and continuous inputs. Finally, ...

  20. Important atomic physics issues for ion beam fusion

    International Nuclear Information System (INIS)

    This paper suggests several current atomic physics questions important to ion beam fusion. Among the topics discussed are beam transport, beam-target interaction, and reactor design. The major part of the report is discussion concerning areas of research necessary to better understand beam-target interactions

  1. ATOMIC BEAM STUDIES IN THE RHIC H-JET POLARIMETER.

    Energy Technology Data Exchange (ETDEWEB)

    MAKDISI,Y.; ZELENSKI,A.; GRAHAM,D.; KOKHANOVSKI,S.; MAHLER,G.; NASS,A.; RITTER,J.; ZUBETS,V.; ET AL.

    2005-01-28

    The results of atomic beam production studies are presented. Improved cooling of the atoms before jet formation in the dissociator cold nozzle apparently reduces the atomic beam velocity spread and improves beam focusing conditions. A carefully designed sextupole separating (and focusing) magnet system takes advantage of the high brightness source. As a result a record beam intensity of a 12.4 {center_dot} 10{sup 16} atoms/s was obtained within 10 mm acceptance at the collision point. The results of the polarization dilution factor measurements (by the hydrogen molecules at the collision point) are also presented.

  2. Dual-Beam Atom Laser Driven by Spinor Dynamics

    Science.gov (United States)

    Thompson, Robert; Lundblad, Nathan; Maleki, Lute; Aveline, David

    2007-01-01

    An atom laser now undergoing development simultaneously generates two pulsed beams of correlated Rb-87 atoms. (An atom laser is a source of atoms in beams characterized by coherent matter waves, analogous to a conventional laser, which is a source of coherent light waves.) The pumping mechanism of this atom laser is based on spinor dynamics in a Bose-Einstein condensate. By virtue of the angular-momentum conserving collisions that generate the two beams, the number of atoms in one beam is correlated with the number of atoms in the other beam. Such correlations are intimately linked to entanglement and squeezing in atomic ensembles, and atom lasers like this one could be used in exploring related aspects of Bose-Einstein condensates, and as components of future sensors relying on atom interferometry. In this atom-laser apparatus, a Bose-Einstein condensate of about 2 x 10(exp 6) Rb-87 atoms at a temperature of about 120 micro-K is first formed through all-optical means in a relatively weak singlebeam running-wave dipole trap that has been formed by focusing of a CO2-laser beam. By a technique that is established in the art, the trap is loaded from an ultrahigh-vacuum magnetooptical trap that is, itself, loaded via a cold atomic beam from an upstream two-dimensional magneto-optical trap that resides in a rubidium-vapor cell that is differentially pumped from an adjoining vacuum chamber, wherein are performed scientific observations of the beams ultimately generated by the atom laser.

  3. Feshbach-resonance-induced atomic filamentation and quantum pair correlation in atom-laser-beam propagation

    OpenAIRE

    Zhang, Weiping; Search, Chris P.; Pu, Han; Meystre, Pierre; Wright, Ewan M.

    2002-01-01

    We study the propagation of an atom laser beam through a spatial region with a magnetic field tuned to a Feshbach resonance. Tuning the magnetic field below the resonance produces an effective focusing Kerr medium that causes a modulational instability of the atomic beam. Under appropriate circumstances, this results in beam breakup and filamentation seeded by quasi-particle fluctuations, and in the generation of correlated atomic pairs.

  4. Beams made of twisted atoms: A theoretical analysis

    International Nuclear Information System (INIS)

    We have analyzed Bessel beams of two-level atoms that are driven by a linearly polarized laser light. Based on the Schroedinger equation for two-level systems, we first determine the states of two-level atoms in a plane-wave field by taking into account propagation directions both of the atom and the field. For such laser-driven two-level atoms, we construct Bessel beams by going beyond the typical paraxial approximation. In particular, we show that the probability density of these atomic beams exhibits a non-trivial, Bessel-squared-type behavior. The profile of such twisted atoms is affected by atom and laser parameters, such as the nuclear charge, atom velocity, laser frequency, and propagation geometry of the atom and laser beams. Moreover, we spatially and temporally characterize the beam of hydrogen and selected (neutral) alkali-metal atoms that carry non-zero orbital angular momentum (OAM). The proposed spatiotemporal Bessel states (i) are able to describe twisted states of any two-level system which is driven by the radiation field and (ii) have potential applications in atomic and nuclear processes as well as in quantum communication.

  5. An atomic beam fluorescence locked magneto-optical trap for krypton atoms

    International Nuclear Information System (INIS)

    We report here an atomic beam loaded magneto-optical trap (MOT) for metastable krypton atoms in which the fluorescence signal from the atomic beam is used to lock the cooling laser frequency. The fluorescence signal is generated by exciting the metastable krypton atomic beam using a probe laser beam (i.e. part of the cooling laser beam) intersecting the atomic beam at an angle. A spectral shift in the fluorescence signal can be achieved by varying the angle between the probe laser beam and the atomic beam to obtain the desired frequency detuning to lock the cooling laser frequency. This has been used to optimize the number of cold atoms in the MOT. The dependence of the peak height and slope of the atomic beam fluorescence (ABF) locking signal on the RF power in the discharge tube and pressure in the observation chamber of the setup has been studied to correlate its effect on the number of atoms in the MOT. (paper)

  6. Relative-velocity distributions for two effusive atomic beams in counterpropagating and crossed-beam geometries

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke

    2012-01-01

    Formulas are presented for calculating the relative velocity distributions in effusive, orthogonal crossed beams and in effusive, counterpropagating beams experiments, which are two important geometries for the study of collision processes between atoms. In addition formulas for the distributions...

  7. PYRAMIDAL-HOLLOW-BEAM DIPOLE TRAP FOR ALKALI ATOMS

    Institute of Scientific and Technical Information of China (English)

    YIN JIAN-PING; GAO WEI-JIAN; WANG YU-ZHU; ZHU YI-FU; WANG YI-QIU

    2000-01-01

    We propose a dark gravito-optical dipole trap, for alkali atoms, consisting of a blue-detuned, pyramidal-hollow laser beam propagating upward and the gravity field. When cold atoms from a magneto-optical trap are loaded into the pyramidal-hollow beam and bounce inside the pyramidal-hollow beam, they experience efficient Sisyphus cooling and geometric cooling induced by the pyramidal-hollow beam and the weak repumping beam propagating downward. Our study shows that an ultracold and dense atomic sample with an equilibrium 3D momentum of ~ 3hk and an atomic density above the point of Bose-Einstein condensation may be obtained in this pure optical trap.

  8. Laser cooling of a magnetically guided ultra cold atom beam

    Energy Technology Data Exchange (ETDEWEB)

    Aghajani-Talesh, Anoush

    2014-07-01

    This thesis examines two complimentary methods for the laser cooling of a magnetically guided ultra-cold atom beam. If combined, these methods could serve as a starting point for high-through put and possibly even continuous production of Bose-Einstein condensates. First, a mechanism is outlined to harvest ultra cold atoms from a magnetically guided atom beam into an optical dipole trap. A continuous loading scheme is described that dissipates the directed kinetic energy of a captured atom via deceleration by a magnetic potential barrier followed by optical pumping to the energetically lowest Zeeman sublevel. The application of this scheme to the transfer of ultra cold chromium atoms from a magnetically guided atom beam into a deep optical dipole trap is investigated via numerical simulations of the loading process. Based on the results of the theoretical studies the feasibility and the efficiency of our loading scheme, including the realisation of a suitable magnetic field configuration, are analysed. Second, experiments were conducted on the transverse laser cooling of a magnetically guided beam of ultra cold chromium atoms. Radial compression by a tapering of the guide is employed to adiabatically heat the beam. Inside the tapered section heat is extracted from the atom beam by a two-dimensional optical molasses perpendicular to it, resulting in a significant increase of atomic phase space density. A magnetic offset field is applied to prevent optical pumping to untrapped states. Our results demonstrate that by a suitable choice of the magnetic offset field, the cooling beam intensity and detuning, atom losses and longitudinal heating can be avoided. Final temperatures below 65 μK have been achieved, corresponding to an increase of phase space density in the guided beam by more than a factor of 30.

  9. Laser cooling of a magnetically guided ultra cold atom beam

    International Nuclear Information System (INIS)

    This thesis examines two complimentary methods for the laser cooling of a magnetically guided ultra-cold atom beam. If combined, these methods could serve as a starting point for high-through put and possibly even continuous production of Bose-Einstein condensates. First, a mechanism is outlined to harvest ultra cold atoms from a magnetically guided atom beam into an optical dipole trap. A continuous loading scheme is described that dissipates the directed kinetic energy of a captured atom via deceleration by a magnetic potential barrier followed by optical pumping to the energetically lowest Zeeman sublevel. The application of this scheme to the transfer of ultra cold chromium atoms from a magnetically guided atom beam into a deep optical dipole trap is investigated via numerical simulations of the loading process. Based on the results of the theoretical studies the feasibility and the efficiency of our loading scheme, including the realisation of a suitable magnetic field configuration, are analysed. Second, experiments were conducted on the transverse laser cooling of a magnetically guided beam of ultra cold chromium atoms. Radial compression by a tapering of the guide is employed to adiabatically heat the beam. Inside the tapered section heat is extracted from the atom beam by a two-dimensional optical molasses perpendicular to it, resulting in a significant increase of atomic phase space density. A magnetic offset field is applied to prevent optical pumping to untrapped states. Our results demonstrate that by a suitable choice of the magnetic offset field, the cooling beam intensity and detuning, atom losses and longitudinal heating can be avoided. Final temperatures below 65 μK have been achieved, corresponding to an increase of phase space density in the guided beam by more than a factor of 30.

  10. A Compact, High-Flux Cold Atom Beam Source

    Science.gov (United States)

    Kellogg, James R.; Kohel, James M.; Thompson, Robert J.; Aveline, David C.; Yu, Nan; Schlippert, Dennis

    2012-01-01

    The performance of cold atom experiments relying on three-dimensional magneto-optical trap techniques can be greatly enhanced by employing a highflux cold atom beam to obtain high atom loading rates while maintaining low background pressures in the UHV MOT (ultra-high vacuum magneto-optical trap) regions. Several techniques exist for generating slow beams of cold atoms. However, one of the technically simplest approaches is a two-dimensional (2D) MOT. Such an atom source typically employs at least two orthogonal trapping beams, plus an additional longitudinal "push" beam to yield maximum atomic flux. A 2D atom source was created with angled trapping collimators that not only traps atoms in two orthogonal directions, but also provides a longitudinal pushing component that eliminates the need for an additional push beam. This development reduces the overall package size, which in turn, makes the 2D trap simpler, and requires less total optical power. The atom source is more compact than a previously published effort, and has greater than an order of magnitude improved loading performance.

  11. An Atomic Lens Using a Focusing Hollow Beam

    Institute of Scientific and Technical Information of China (English)

    夏勇; 印建平; 王育竹

    2003-01-01

    We propose a new method to generate a focused hollow laser beam by using an azimuthally distributed 2π-phase plate and a convergent thin lens, and calculate the intensity distribution of the focused hollow beam in free propagation space. The relationship between the waist w0 of the incident collimated Gaussian beam and the dark spot size of the focused hollow beam at the focal point, and the relationship between the focal length f of the thin lens and the dark spot size are studied respectively. The optical potential of the blue-detuned focused hollow beam for 85Rb atoms is calculated. Our study shows that when the larger waist w of the incident Gaussian beam and the shorter focal length f of the lens are chosen, we can obtain an extremely small dark spot size of the focused hollow beam, which can be used to form an atomic lens with a resolution of several angstroms.

  12. Demonstration of a cold atom beam splitter on atom chip

    Science.gov (United States)

    Jiang, Xiaojun; Li, Xiaolin; Zhang, Haichao; Wang, Yuzhu

    2016-08-01

    We report an experimental demonstration of a new scheme to split cold atoms on an atom chip. The atom chip consists of a U-wire and a Z-wire. The cold atom cloud is initially loaded and prepared in the Z-trap, which is split into two separate parts by switching on the current of the U-wire. The two separate atom clouds have a distance more than one millimeter apart from each other and show almost symmetrical profiles, corresponding to about a 50/50 splitting ratio. Project supported by the State Key Basic Research Program of China (Grant No. 2011CB921504) and the National Natural Science Foundation of China (Grant No. 91536107).

  13. Vacuum ultraviolet laser induced fluorescence on a Si atomic beam

    Science.gov (United States)

    O'Brian, T. R.; Lawler, J. E.

    1991-01-01

    A broadly applicable vacuum ultraviolet experiment is described for measuring radiative lifetimes of neutral and singly-ionized atoms in a beam environment to 5-percent accuracy using laser induced fluorescence. First results for neutral Si are reported.

  14. Development of the RIKEN atomic beam type polarized ion source

    International Nuclear Information System (INIS)

    The RIKEN atomic beam type polarized ion source has been assembled and is operational. The present level of performance is 140 μA with 50-60% polarization of the ideal value. Results from operation will be described. (author)

  15. Theoretical tools for atom-laser-beam propagation

    OpenAIRE

    Riou, Jean-Félix; Le Coq, Yann; Impens, François; Guerin, William; Bordé, Christian,; Aspect, Alain; Bouyer, Philippe

    2008-01-01

    We present a theoretical model for the propagation of non self-interacting atom laser beams. We start from a general propagation integral equation, and we use the same approximations as in photon optics to derive tools to calculate the atom laser beam propagation. We discuss the approximations that allow to reduce the general equation whether to a Fresnel-Kirchhoff integral calculated by using the stationary phase method, or to the eikonal. Within the paraxial approximation, we also introduce...

  16. Atom gratings produced by large angle atom beam splitters

    OpenAIRE

    Dubetsky, B.; Berman, P. R.

    2001-01-01

    An asymptotic theory of atom scattering by large amplitude periodic potentials is developed in the Raman-Nath approximation. The atom grating profile arising after scattering is evaluated in the Fresnel zone for triangular, sinusoidal, magneto-optical, and bichromatic field potentials. It is shown that, owing to the scattering in these potentials, two \\QTR{em}{groups} of momentum states are produced rather than two distinct momentum components. The corresponding spatial density profile is cal...

  17. NOx reduction by electron beam-produced nitrogen atom injection

    Science.gov (United States)

    Penetrante, Bernardino M.

    2002-01-01

    Deactivated atomic nitrogen generated by an electron beam from a gas stream containing more than 99% N.sub.2 is injected at low temperatures into an engine exhaust to reduce NOx emissions. High NOx reduction efficiency is achieved with compact electron beam devices without use of a catalyst.

  18. 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".

  19. Cascaded two-photon spectroscopy of Yb atoms with a transportable effusive atomic beam apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Song, Minsoo; Yoon, Tai Hyun [Department of Physics, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-713 (Korea, Republic of)

    2013-02-15

    We present a transportable effusive atomic beam apparatus for cascaded two-photon spectroscopy of the dipole-forbidden transition (6s{sup 2} {sup 1}S{sub 0}{r_reversible} 6s7s {sup 1}S{sub 0}) of Yb atoms. An ohmic-heating effusive oven is designed to have a reservoir volume of 1.6 cm{sup 3} and a high degree of atomic beam collimation angle of 30 mrad. The new atomic beam apparatus allows us to detect the spontaneously cascaded two-photons from the 6s7s{sup 1}S{sub 0} state via the intercombination 6s6p{sup 3}P{sub 1} state with a high signal-to-noise ratio even at the temperature of 340 Degree-Sign C. This is made possible in our apparatus because of the enhanced atomic beam flux and superior detection solid angle.

  20. Cascaded two-photon spectroscopy of Yb atoms with a transportable effusive atomic beam apparatus.

    Science.gov (United States)

    Song, Minsoo; Yoon, Tai Hyun

    2013-02-01

    We present a transportable effusive atomic beam apparatus for cascaded two-photon spectroscopy of the dipole-forbidden transition (6s(2)(1)S0↔ 6s7s (1)S0) of Yb atoms. An ohmic-heating effusive oven is designed to have a reservoir volume of 1.6 cm(3) and a high degree of atomic beam collimation angle of 30 mrad. The new atomic beam apparatus allows us to detect the spontaneously cascaded two-photons from the 6s7s(1)S0 state via the intercombination 6s6p(3)P1 state with a high signal-to-noise ratio even at the temperature of 340 °C. This is made possible in our apparatus because of the enhanced atomic beam flux and superior detection solid angle. PMID:23464193

  1. Isotopically selective optical deflection of a krypton atomic beam

    International Nuclear Information System (INIS)

    We deflected a well-collimated beam of krypton atoms in the metastable 1s5 state by radiation pressure from a single-frequency dye laser. To produce the radiation pressure, we resonantly excited the krypton atoms, using the 1s5--2p9 transition. The natural width of this transition is much smaller than its isotope shift, which allowed us to deflect one isotope at a time. This created a new isotopically enriched atomic beam of Kr(1s5). We achieved a maximum enrichment factor of 1.2 x 104 at a deflection angle of 19 mrad. This enrichment is limited mainly by scattering of the parent atomic beam by residual gas. This degree of enrichment may make it possible to perform sensitive measurements of the concentrations of rare krypton isotopes in environmental samples

  2. Atomic-Beam Magnetic Resonance Experiments at ISOLDE

    CERN Multimedia

    2002-01-01

    The aim of the atomic-beam magnetic resonance (ABMR) experiments at ISOLDE is to map the nuclear behaviour in wide regions of the nuclear chart by measuring nuclear spins and moments of ground and isomeric states. This is made through an investigation of the atomic hyperfine structure of free, neutral atoms in a thermal atomic-beam using radio-frequency techniques. On-line operation allows the study of short-lived nuclei far from the region of beta-stability.\\\\ \\\\ The ABMR experiments on the |2S^1 ^2 elements Rb, Cs, Au and Fr have been completed, and present efforts are directed towards the elements with an open p-shell and on the rare-earth elements.\\\\ \\\\ The experimental data obtained are compared with results from model calculations, giving information on the single-particle structure and on the nuclear shape parameters.

  3. Atomic Beam Probe Diagnostic for COMPASS Tokamak

    Czech Academy of Sciences Publication Activity Database

    Háček, Pavel; Weinzettl, Vladimír; Stöckel, Jan; Anda, G.; Veres, G.; Zoletnik, S.; Berta, M.

    Vol. 2. Prague: MATFYZPRESS, 2010 - (Šafránková, J.; Pavlů, J.), s. 7-11. (WDS'10). ISBN 978-80-7378-140-8. [Annual Conference of Doctoral Students - WDS 2010 /19th./. Prague (CZ), 01.06.2010-04.06.2010] R&D Projects: GA ČR GA202/09/1467 Institutional research plan: CEZ:AV0Z20430508 Keywords : plasma diagnostics * tokamak * COMPASS * beam diagnostics Subject RIV: BL - Plasma and Gas Discharge Physics http://server.ipp.cas.cz/~vwei/work/wds2010_201_f2.pdf

  4. The FILTEX/HERMES polarized hydrogen atomic beam source

    International Nuclear Information System (INIS)

    The FILTEX/HERMES atomic beam source (ABS) for polarized hydrogen is described. Recent improvements concern mainly the optimization of the beam forming system and a new design of the sextupole magnet system. For a precise measurement (error 5%) of the output flow a calibrated compression tube was installed. The output flow of 0.81x1017 H atoms per second in two hyperfine substates was constant within 2% in a long-term measurement over 16 h. At the FILTEX test experiment, the target density in the storage cell fed by the ABS was constant within the experimental error of 4% over a period of four months. (orig.)

  5. Ultra thin coherent atom beam by Stern-Gerlach interferometry

    Science.gov (United States)

    Perales, F.; Robert, J.; Baudon, J.; Ducloy, M.

    2007-06-01

    It is demonstrated that a Stern-Gerlach interferometer including a special transverse phase shifter can generate an atomic beam of a small diameter (few tens of nm). Calculations carried out in a coherent regime confirm this point. They also show that the device is almost insensitive to velocity dispersion and that the required mechanical accuracy is quite accessible. Due to the peculiar transverse amplitude distribution (of the Lorentz type), the spreading of the generated beam profile is very small compared to that given by a circular diaphragm or a Gaussian profile of comparable initial diameter. This is a key property as regards applications, e.g. in atom lithography and surface probing.

  6. Sensitive spectroscopy of an ytterbium atomic beam

    CERN Document Server

    Guttridge, A; Kemp, S L; Boddy, D; Freytag, R; Tarbutt, M R; Hinds, E A; Cornish, S L

    2015-01-01

    Experimental studies of ultracold ytterbium atoms generally involve the frequency stabilisation (locking) of lasers to two transitions at 399 and 556 nm in order to implement laser cooling. Here we present a simple and robust apparatus for generation of suitable, narrow fluorescence signals with a high signal to noise ratio at both wavelengths. The design utilises easily acquired vacuum parts, optics and electronics and requires very little laser power. We demonstrate the stability and precision of the frequency stabilisation at 556 nm by presenting sensitive measurements of the gravitational sag of an ytterbium MOT as a function of laser power.

  7. Molecular Beam Studies of Hot Atom Chemical Reactions: Reactive Scattering of Energetic Deuterium Atoms

    Science.gov (United States)

    Continetti, R. E.; Balko, B. A.; Lee, Y. T.

    1989-02-01

    A brief review of the application of the crossed molecular beams technique to the study of hot atom chemical reactions in the last twenty years is given. Specific emphasis is placed on recent advances in the use of photolytically produced energetic deuterium atoms in the study of the fundamental elementary reactions D + H{sub 2} -> DH + H and the substitution reaction D + C{sub 2}H{sub 2} -> C{sub 2}HD + H. Recent advances in uv laser and pulsed molecular beam techniques have made the detailed study of hydrogen atom reactions under single collision conditions possible.

  8. Nanoscale focused ion beam from laser-cooled lithium atoms

    International Nuclear Information System (INIS)

    We demonstrate a new type of nanoscale focused ion beam (FIB) based on photoionizing laser-cooled atoms held at millikelvin temperatures in a magneto-optical trap (MOT). This new source expands the range of available ionic species and accessible ion beam energies for FIBs, enhancing their role as one of the most important tools for nanoscale characterization and fabrication. We show examples of microscopy with lithium ions obtained by scanning the FIB and collecting the resulting secondary electrons, and characterize the beam focus by a 25-75% rise distance measurement of (26.7 ± 1.0) nm at a beam energy of 2 keV. We also examine the dependence of the focal size on MOT temperature and beam energy. (paper)

  9. Atomic beam study of a superconductor's magnetic vortex lattice

    International Nuclear Information System (INIS)

    We have developed an atomic beam technique for studying magnetic vortices and vortex lattices of superconductors. Atoms moving near a superconductor's surface see a fluctuating magnetic field as they pass vortices. This field may drive magnetic resonance transitions between hyperfine states. Measuring the magnetic resonance transition probability as a function of atom velocity probes the vortex lattice autocorrelation function. We demonstrate this technique by studying the vortex lattice of a niobium film sample and measuring the sample's penetration depth. We also identify a systematic problem that we think thwarted an earlier attempt to experimentally realize this technique. copyright 1997 The American Physical Society

  10. Guiding cold atoms in a hollow laser beam

    Science.gov (United States)

    Xu, Xinye; Minogin, V. G.; Lee, Kwanil; Wang, Yuzhu; Jhe, Wonho

    1999-12-01

    The theory of atom guiding in a far blue-detuned hollow laser beam (HLB) is developed for the dipole interaction scheme described by a three-level Λ model. The complete kinetic description of atomic motion based on the Fokker-Planck equation for the atomic distribution function is presented. The dipole gradient force, radiation pressure force, and momentum diffusion tensor are then derived. It is found that even for a far-detuned laser beam, the optical potential for a three-level Λ atom is not generally reduced to a sum of two independent potentials associated with the two two-level interactions in the Λ scheme. The theory developed here is also compared with the experimental guiding of cold 85Rb atoms in the HLB. The experimental results are found to be in good agreement with the Monte Carlo simulations based on the three-level Λ model. We observe that the guiding efficiency depends strongly on the intensity and the detuning of the HLB and the initial temperature of atoms. In particular, the experimental results show that, at small detunings, the guiding efficiency is deteriorated strongly by the radiation pressure force. The Monte Carlo simulations also indicate that the efficiency of guiding versus detuning depends strongly on the direction of the HLB propagation with respect to that of atomic motion. Under optimal conditions, the guiding efficiency was found to be about 20%.

  11. Doppler-free spectroscopy on tantalum atomic beam

    International Nuclear Information System (INIS)

    We demonstrate the usefulness of an atomic beam source for refractory metals in Doppler-free spectroscopy. The splittings between seven hyperfine components of the weak 578.01 nm transition in TaI are measured to +- 1 MHz. The hyperfine A and B coefficients for the upper and lower level are determined from the observed splittings. (orig.)

  12. Atomic Beam Laser Spectrometer for In-field Isotopic Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Alonso [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Actinide Analytical Chemistry Group

    2016-06-22

    This is a powerpoint presentation for the DTRA quarterly program review that goes into detail about the atomic beam laser spectrometer for in-field isotopic analysis. The project goals are the following: analysis of post-detonation debris, determination of U and Pu isotopic composition, and fieldable prototype: < 2ft3, < 1000W.

  13. Optimization of atomic beam sources for polarization experiments

    Energy Technology Data Exchange (ETDEWEB)

    Gaisser, Martin; Nass, Alexander; Stroeher, Hans [IKP, Forschungszentrum Juelich (Germany)

    2013-07-01

    For experiments with spin-polarized protons and neutrons a dense target is required. In current atomic beam sources an atomic hydrogen or deuterium beam is expanded through a cold nozzle and a system of sextupole magnets and RF-transition units selects a certain hyperfine state. The achievable flux seems to be limited to about 10{sup 17} particles per second with a high nuclear polarization. A lot of experimental and theoretical effort has been undertaken to understand all effects and to increase the flux. However, improvements have remained marginal. Now, a Monte Carlo simulation based on the DSMC part of the open source C++ library OpenFOAM is set up in order to get a better understanding of the flow and to optimize the various elements. It is intended to include important effects like deflection from magnetic fields, recombination on the walls and spin exchange collisions in the simulation and make quantitative predictions of changes in the experimental setup. The goal is to get a tool that helps to further increase the output of an atomic beam source. So far, a new binary collision model, magnetic fields, RF-transition units and a tool to measure the collision age are included. The next step will be to couple the whole simulation with an optimization algorithm implementing Adaptive Simulated Annealing (ASA) in order to automatically optimize the atomic beam source.

  14. Development of a Supersonic Atomic Oxygen Nozzle Beam Source for Crossed Beam Scattering Experiments

    Science.gov (United States)

    Sibener, S. J.; Buss, R. J.; Lee, Y. T.

    1978-05-01

    A high pressure, supersonic, radio frequency discharge nozzle beam source was developed for the production of intense beams of ground state oxygen atoms. An efficient impedance matching scheme was devised for coupling the radio frequency power to the plasma as a function of both gas pressure and composition. Techniques for localizing the discharge directly behind the orifice of a water-cooled quartz nozzle were also developed. The above combine to yield an atomic oxygen beam source which produces high molecular dissociation in oxygen seeded rare gas mixtures at total pressures up to 200 torr: 80 to 90% dissociation for oxygen/argon mixtures and 60 to 70% for oxygen/helium mixtures. Atomic oxygen intensities are found to be greater than 10{sup 17} atom sr{sup -1} sec{sup -1}. A brief discussion of the reaction dynamics of 0 + IC1 ..-->.. I0 + C1 is also presented.

  15. Enabling Nanotechnology with Focused Ion Beams from Laser Cooled Atoms

    Science.gov (United States)

    Steele, A. V.; Knuffman, B.; Orloff, J.; Maazouz, M.; McClelland, J. J.

    2011-05-01

    The Magneto-Optical Trap Ion Source (MOTIS) being developed at NIST has the potential to enable numerous advances in nanoscale science. In a MOTIS, atoms are captured into a MOT, photoionized, and accelerated to an energy of a few hundred eV to a few tens of kV. A beam formed in this way can be brought to a tight focus, competitive with the commercial focused ion beam machines deployed widely today. Additionally, the unique characteristics of this source, coupled with the user's choice of ion from the long and growing list of laser-coolable atomic species suggest that the MOTIS has the potential to advance the state of the art in applications such as imaging, nanofabrication, secondary ion mass spectrometry, and others. I will present high-resolution images from our lithium and chromium MOTIS-based focused ion beams and discuss applications which we will pursue with these new tools.

  16. An atomic beam source for actinide elements: concept and realization

    International Nuclear Information System (INIS)

    For ultratrace analysis of actinide elements and studies of their atomic properties with resonance ionization mass spectroscopy (RIMS), efficient and stable sources of actinide atomic beams are required. The thermodynamics and kinetics of the evaporation of actinide elements and oxides from a variety of metals were considered, including diffusion, desorption, and associative desorption. On this basis various sandwich-type filaments were studied. The most promising system was found to consist of tantalum as the backing material, an electrolytically deposited actinide hydroxide as the source of the element, and a titanium covering layer for its reduction to the metal. Such sandwich sources were experimentally proven to be well suited for the production of atomic beams of plutonium, curium, berkelium and californium at relatively low operating temperatures and with high and reproducible yields. (orig.)

  17. Ramsey fringes in a thermal beam of Yb atoms

    CERN Document Server

    Rathod, K D

    2014-01-01

    We use the Ramsey separated oscillatory fields (SOF) technique in a $400^\\circ$C thermal beam of Yb atoms to measure the Larmor precession frequency with high precision. For the experiment, we use the strongly-allowed ${^1S_0} \\rightarrow {^1P_1}$ transition at $399$ nm, and choose the odd isotope $^{171}$Yb with nuclear spin $I=1/2$, so that the ground state has only two magnetic sublevels $m_F = \\pm 1/2$. With a magnetic field of $22.2$ G and a separation of about $400$ mm between the oscillatory fields, the central Ramsey fringe is at $16.64$ kHz and has a width of $350$ Hz. The technique can be readily adapted to a cold atomic beam, and should be useful in experiments searching for a permanent electric dipole moment (EDM) in atoms.

  18. Theory of longitudinal atomic beam spin echo and parity violating Berry-phases in atoms

    International Nuclear Information System (INIS)

    We present a nonrelativistic theory for the quantum mechanical description of longitudinal atomic beam spin echo experiments, where a beam of neutral atoms is subjected to static electric and magnetic fields. The atomic wave function is the solution of a matrix-valued Schroedinger equation and can be written as superposition of local (atomic) eigenstates of the potential matrix. The position- and time-dependent amplitude function of each eigenstate represents an atomic wave packet and can be calculated in a series expansion with a master formula that we derive. The zeroth order of this series expansion describes the adiabatic limit, whereas the higher order contributions contain the mixing of the eigenstates and the corresponding amplitude functions. We give a tutorial for the theoretical description of longitudinal atomic beam spin echo experiments and for the so-called Fahrplan model, which is a visualisation tool for the propagation of wave packets of different atomic eigenstates. As an example for the application of our theory, we study parity violating geometric (Berry-)phases. In this context, we define geometric flux densities, which for certain field configurations can be used to illustrate geometric phases in a vector diagram. Considering an example with a specific field configuration, we prove the existence of a parity violating geometric phase. (orig.)

  19. A microwave discharge atom beam source of high intensity

    International Nuclear Information System (INIS)

    A 2.45 GHz microwave discharge atom beam source of compact design has been developed. A standard extended quarter wavelength cavity design has been used in conjunction with a simple discharge tube and cooling arrangement. The source, while primarily designed for the production of atomic hydrogen, has also been tested with oxygen and nitrogen. The characteristics of the microwave source are compared with those of a Slevin type radiofrequency RF source and the influence of different cleaning procedures on performance have been investigated. Unlike the Slevin source the performance of the microwave source is not critically dependent on the cleaning procedure or gas purity. For hydrogen, both sources could provide a dissociation fraction of about 90% but the beam intensity obtainable from the microwave source (>1014 atoms cm-3) at the exit of a 1 mm capillary tube was significantly greater than that from the Slevin source. For oxygen, where the performance of the Slevin source was poor, the microwave source provided a dissociation fraction of up to about 60% and a beam density of about 1013 atoms cm-3. (Author)

  20. A microwave discharge atom beam source of high intensity

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, A.; Hughes, M.P.; Geddes, J.; Gilbody, H.B. (Queen' s Univ., Belfast, Northern Ireland (United Kingdom). Dept. of Pure and Applied Physics)

    1992-05-01

    A 2.45 GHz microwave discharge atom beam source of compact design has been developed. A standard extended quarter wavelength cavity design has been used in conjunction with a simple discharge tube and cooling arrangement. The source, while primarily designed for the production of atomic hydrogen, has also been tested with oxygen and nitrogen. The characteristics of the microwave source are compared with those of a Slevin type radiofrequency RF source and the influence of different cleaning procedures on performance have been investigated. Unlike the Slevin source the performance of the microwave source is not critically dependent on the cleaning procedure or gas purity. For hydrogen, both sources could provide a dissociation fraction of about 90% but the beam intensity obtainable from the microwave source (>10{sup 14} atoms cm{sup -3}) at the exit of a 1 mm capillary tube was significantly greater than that from the Slevin source. For oxygen, where the performance of the Slevin source was poor, the microwave source provided a dissociation fraction of up to about 60% and a beam density of about 10{sup 13} atoms cm{sup -3}. (Author).

  1. Characterization of a cryogenic beam source for atoms and molecules

    CERN Document Server

    Bulleid, N E; Hendricks, R J; Sauer, B E; Hinds, E A; Tarbutt, M R

    2013-01-01

    We present a combined experimental and theoretical study of beam formation from a cryogenic buffer gas cell. Atoms and molecules are loaded into the cell by laser ablation of a target, and are cooled and swept out of the cell by a flow of cold helium. We study the thermalization and flow dynamics inside the cell and measure how the speed, temperature, divergence and extraction efficiency of the beam are influenced by the helium flow. We use a finite element model to simulate the flow dynamics and use the predictions of this model to interpret our experimental results.

  2. Entanglement of atomic beams: Tests of complementarity and other applications

    International Nuclear Information System (INIS)

    It is shown that distinct atomic beams can be entangled when they interact with quantum superpositions of macroscopically separated micromaser fields. Experimentally feasible tests of complementarity are proposed, detecting Ramsey interference (or not) in one and open-quote open-quote Welcher Weg close-quote close-quote information (or not) in the other entangled beam. Available information and fringe contrast can be manipulated using classical and quantum fields. The open-quote open-quote quantum eraser close-quote close-quote is realized in the former case, while it is only a special feature in the latter one. Other applications of entangled atoms are also suggested. copyright 1996 The American Physical Society

  3. The effect of laser beam size in a zig-zag collimator on transverse cooling of a krypton atomic beam

    Indian Academy of Sciences (India)

    Vivek Singh; V B Tiwari; S Singh; S R Mishra; H S Rawat

    2014-07-01

    The effect of size of a cooling laser beam in a zig-zag atomic beam collimator on transverse cooling of a krypton atomic beam is investigated. The simulation results show that discreteness in the interaction between the cooling laser beam and atomic beam, arising due to finite size and incidence angle of the cooling laser beam, significantly reduces the value of transverse velocity capture range of the collimator. The experimental observations show the trend similar to that obtained from simulations. Our study can be particularly useful where a small zig-zag collimator is required.

  4. Workshop on the use of atomic beams in plasma experiments

    International Nuclear Information System (INIS)

    The material of the workshop entitled 'Use of Atomic Beams in Plasma Experiments', which was organized to summarize the results of the joint research and to give an outlook to the future trends of development in the field is presented. Different topics on plasma diagnostics, plasma impurities, impurity injection, transport theory in plasma and their use in tokamak devices are covered. 18 items are separately indexed for INIS database. (K.A.)

  5. Proposal for a magneto-optical beam splitter for atoms

    OpenAIRE

    Pfau, Tilman; Adams, Charles S.; Mlynek, Jürgen

    1993-01-01

    In this letter we present a theoretical study of the coherent diffraction of three-level atoms from a light field with a polarization gradient (counterpropagating crossed linearly polarized beams) and a static magnetic field applied parallel to the laser propagation direction. We show that for a particular ratio of the laser field intensity and the magnetic-field strength, there occurs a resonance between the Larmor precession of the magnetic alignment and the Rabi oscillations. On resonance ...

  6. 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.

  7. Neutral atom beam technique enhances bioactivity of PEEK

    International Nuclear Information System (INIS)

    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

  8. Neutral atom beam technique enhances bioactivity of PEEK

    Science.gov (United States)

    Khoury, Joseph; Kirkpatrick, Sean R.; Maxwell, Melissa; Cherian, Raymond E.; Kirkpatrick, Allen; Svrluga, Richard C.

    2013-07-01

    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.

  9. Measurements of atomic transition probabilities in highly ionized atoms by fast ion beams

    International Nuclear Information System (INIS)

    A summary is given of the beam-foil method by which level lifetimes and transition probabilities can be determined in atoms and ions. Results are presented for systems of particular interest for fusion research, such as the Li, Be, Na, Mg, Cu and Zn isoelectronic sequences. The available experimental material is compared to theoretical transition probabilities. (author)

  10. Optimization of atomic beam sources for polarization experiments

    Energy Technology Data Exchange (ETDEWEB)

    Gaisser, Martin; Nass, Alexander; Stroeher, Hans [IKP, Forschungszentrum Juelich (Germany)

    2012-07-01

    For experiments with spinpolarized protons and neutrons a dense target is required. In current atomic beam sources an atomic hydrogen or deuterium beam is expanded through a cold nozzle and a system of sextupole magnets and RF-transition units selects a certain hyperfine state. The achievable flux seems to be limited to about 10{sup 17} particles per second with a high nuclear polarization. A lot of experimental and theoretical effort has been undertaken to understand all effects and to increase the flux. However, improvements have remained marginal. Now, a Monte Carlo simulation based on the DSMC part of the open source C++ library OpenFOAM is set up in order to get a better understanding of the flow and to optimize the various elements. The goal is to include important effects like deflection from a magnetic field, recombination on the walls and spin exchange collisions in the simulation and make quantitative predictions of changes in the experimental setup. The goal is to get a tool that helps to further increase the output of an atomic beam source.

  11. Production of heavy ion beams for atomic physics studies

    International Nuclear Information System (INIS)

    A laboratory for research in atomic physics of ions has been set up around a 2 MV tandem Van de Graaff accelerator designed and built indegenously. Mass analysed negatively charged heavy ion beams from a directly extracted duoplasmatron ion source are injected through various ion-optical elements into the accelerating tube. A gas stripper at the high voltage dome changes the negative ions into positive ions which are subsequently accelerated. The high energy end of the accelerator consists of quadrupole focussing magnets and an analysing magnet. A pair of insulated tantalum slits provide corona feedback and stabilize the energy of the accelerator. A beam resolution of 5 keV at 1 MeV proton energy has been measured. A number of experiments are presently being planned to utilize the accelerator in the field of basic research in atomic physics. These include beam-foil spectroscopic measurements involving detection of decay photon/electrons, ion-induced X-ray emission, analytical applications and radiation damage studies. Electron spectrometers which are in the stage of testing include cylindrical mirror analyser and parallel plate analyser. On the accelerator front, efforts are underway to develop a new sputter ion source and computer automation for improving stability and reliability. The salient features of the accelerator and the instrumentation developed for carrying out experiments in atomic physics are reported. (author). 14 refs., 17 figs

  12. Optimization of atomic beam sources for polarization experiments

    International Nuclear Information System (INIS)

    For experiments with spinpolarized protons and neutrons a dense target is required. In current atomic beam sources an atomic hydrogen or deuterium beam is expanded through a cold nozzle and a system of sextupole magnets and RF-transition units selects a certain hyperfine state. The achievable flux seems to be limited to about 1017 particles per second with a high nuclear polarization. A lot of experimental and theoretical effort has been undertaken to understand all effects and to increase the flux. However, improvements have remained marginal. Now, a Monte Carlo simulation based on the DSMC part of the open source C++ library OpenFOAM is set up in order to get a better understanding of the flow and to optimize the various elements. The goal is to include important effects like deflection from a magnetic field, recombination on the walls and spin exchange collisions in the simulation and make quantitative predictions of changes in the experimental setup. The goal is to get a tool that helps to further increase the output of an atomic beam source.

  13. Focusing Light Beams To Improve Atomic-Vapor Optical Buffers

    Science.gov (United States)

    Strekalov, Dmitry; Matsko, Andrey; Savchenkov, Anatoliy

    2010-01-01

    Specially designed focusing of light beams has been proposed as a means of improving the performances of optical buffers based on cells containing hot atomic vapors (e.g., rubidium vapor). There is also a companion proposal to improve performance by use of incoherent optical pumping under suitable conditions. Regarding the proposal to use focusing: The utility of atomic-vapor optical buffers as optical storage and processing devices has been severely limited by nonuniform spatial distributions of intensity in optical beams, arising from absorption of the beams as they propagate in atomic-vapor cells. Such nonuniformity makes it impossible to optimize the physical conditions throughout a cell, thereby making it impossible to optimize the performance of the cell as an optical buffer. In practical terms simplified for the sake of brevity, "to optimize" as used here means to design the cell so as to maximize the group delay of an optical pulse while keeping the absorption and distortion of the pulse reasonably small. Regarding the proposal to use incoherent optical pumping: For reasons too complex to describe here, residual absorption of light is one of the main impediments to achievement of desirably long group delays in hot atomic vapors. The present proposal is directed toward suppressing residual absorption of light. The idea of improving the performance of slow-light optical buffers by use of incoherent pumping overlaps somewhat with the basic idea of Raman-based slow-light systems. However, prior studies of those systems did not quantitatively answer the question of whether the performance of an atomic vapor or other medium that exhibits electromagnetically induced transparency (EIT) with Raman gain is superior to that of a medium that exhibits EIT without Raman gain.

  14. On-line laser spectroscopy with thermal atomic beams

    CERN Document Server

    Thibault, C; De Saint-Simon, M; Duong, H T; Guimbal, P; Huber, G; Jacquinot, P; Juncar, P; Klapisch, Robert; Liberman, S; Pesnelle, A; Pillet, P; Pinard, J; Serre, J M; Touchard, F; Vialle, J L

    1981-01-01

    On-line high resolution laser spectroscopy experiments have been performed in which the light from a CW tunable dye laser interacts at right angles with a thermal atomic beam. /sup 76-98/Rb, /sup 118-145 /Cs and /sup 208-213/Fr have been studied using the ionic beam delivered by the ISOLDE on-line mass separator at CERN while /sup 30-31/Na and /sup 38-47/K have been studied by setting the apparatus directly on-line with the PS 20 GeV proton beam. The principle of the method is briefly explained and some results concerning nuclear structure are given. The hyperfine structure, spins and isotope shifts of the alkali isotopes and isomers are measured. (8 refs).

  15. Interaction of a deuterium atomic beam with a palladium membrane

    Energy Technology Data Exchange (ETDEWEB)

    Livshits, A.I.; Metter, I.M.; Samartsev, A.A.

    1976-07-01

    It is suggested that under certain conditions the permeability of a solid membrane of the usual thickness for gases can be comparable to the permeability of an aperture in a thin wall. Experiments are carried out to test this suggestion. A study is made of the penetration of deuterium from a thermal atomic beam with a flux density of 10/sup 11/--10/sup 12/ atoms/cm/sup 2/xsec) through an ''inactive'' palladium membrane (i.e., which is comparatively impenetrable for molecular hydrogen). The probability for the penetration of deuterium atoms in a single collision with the membrane over the temperature range 20--520degreeC is independent of the temperature and is equal to 0.1 (i.e., a value of the same order of magnitude as the sticking probability for hydrogen atoms on metals). It is shown experimentally that the desorption is of second order in the concentration of the desolved gas. It is suggested that each atom which recombines at the membrane is first absorbed and then reaches the opposite boundary.

  16. Matter-wave beam splitter on an atom chip for a portable atom-interferometer

    CERN Document Server

    Kim, S J; Gang, S T; Kim, J B

    2016-01-01

    We construct a matter-wave beam splitter using 87Rb Bose-Einstein condensate on an atom chip. Through the use of radio-frequency-induced double-well potentials, we were able to split a BEC into two clouds separated by distances ranging from 2.8 {\\mu}m to 57 {\\mu}m. Interference between these two freely expanding BECs has been observed. By varying the rf-field amplitude, frequency, or polarization, we investigate behaviors of the beam-splitter. From the perspective of practical use, our BEC manipulation system is suitable for application to interferometry since it is compact and the repetition rate is high due to the anodic bonded atom chip on the vacuum cell. The portable system occupies a volume of 0.5 m3 and operates at a repetition rate as high as ~0.2 Hz.

  17. Ramsey fringes in a thermal beam of Yb atoms

    OpenAIRE

    Rathod, K. D.; Natarajan, Vasant

    2014-01-01

    We use the Ramsey separated oscillatory fields (SOF) technique in a $400^\\circ$C thermal beam of Yb atoms to measure the Larmor precession frequency with high precision. For the experiment, we use the strongly-allowed ${^1S_0} \\rightarrow {^1P_1}$ transition at $399$ nm, and choose the odd isotope $^{171}$Yb with nuclear spin $I=1/2$, so that the ground state has only two magnetic sublevels $m_F = \\pm 1/2$. With a magnetic field of $22.2$ G and a separation of about $400$ mm between the oscil...

  18. Atomic lifetime measurements by beam-gas-dye laser spectroscopy

    Science.gov (United States)

    Schmoranzer, H.; Volz, U.

    1993-01-01

    Beam-gas-dye laser spectroscopy as a precise, cascade-free and collision-free method for measuring atomic lifetimes and individual oscillator strengths is described. Its recent application to fine-structure levels of the KrI 5p configuration is reported. The experimental uncertainty is reduced by one order of magnitude, with respect to previous work, down to 0.3% (1σ). The discussion of these results in comparison with experimental and theoretical ones from the literature underlines the precision of the method and its potential to guide future theoretical developments.

  19. Cold beam of isotopically pure Yb atoms by deflection using 1D-optical molasses

    Indian Academy of Sciences (India)

    K D Rathod; P K Singh; Vasant Natarajan

    2014-09-01

    We demonstrate the generation of an isotopically pure beam of laser-cooled Yb atoms by deflection using 1D-optical molasses. Atoms in a collimated thermal beam are first slowed using a Zeeman slower. They are then subjected to a pair of molasses beams inclined at 45° with respect to the slowed atomic beam. The slowed atoms are deflected and probed at a distance of 160 mm. We demonstrate the selective deflection of the bosonic isotope 174Yb and the fermionic isotope 171Yb. Using a transient measurement after the molasses beams are turned on, we find a longitudinal temperature of 41 mK.

  20. Cold beam of isotopically pure Yb atoms by deflection using 1D-optical molasses

    Science.gov (United States)

    Rathod, K. D.; Singh, P. K.; Natarajan, Vasant

    2014-09-01

    We demonstrate generation of an isotopically pure beam of laser-cooled Yb atoms by deflection using 1D-optical molasses. Atoms in a collimated thermal beam are first slowed using a Zeeman Slower. They are then subjected to a pair of molasses beams inclined at $45^\\circ$ with respect to the slowed atomic beam. The slowed atoms are deflected and probed at a distance of 160 mm. We demonstrate selective deflection of the bosonic isotope $^{174}$Yb, and the fermionic isotope $^{171}$Yb. Using a transient measurement after the molasses beams are turned on, we find a longitudinal temperature of 41 mK.

  1. Cold beam of isotopically pure Yb atoms by deflection using 1D-optical molasses

    CERN Document Server

    Rathod, K D; Natarajan, Vasant

    2013-01-01

    We demonstrate generation of an isotopically pure beam of laser-cooled Yb atoms by deflection using 1D-optical molasses. Atoms in a collimated thermal beam are first slowed using a Zeeman Slower. They are then subjected to a pair of molasses beams inclined at $45^\\circ$ with respect to the slowed atomic beam. The slowed atoms are deflected and probed at a distance of 160 mm. We demonstrate selective deflection of the bosonic isotope $^{174}$Yb, and the fermionic isotope $^{171}$Yb. Using a transient measurement after the molasses beams are turned on, we find a longitudinal temperature of 41 mK.

  2. One Atomic Beam as a Detector of Classical Harmonic Vibrations with Micro Amplitudes and Low Frequencies

    CERN Document Server

    Wong, Werner

    2013-01-01

    We propose a simplest detector of harmonic vibrations with micro amplitudes and low frequencies, i.e. the detector consisting of one atomic beam. Here the atomic beam is induced by a plane harmonic wave and has a classical collective harmonic vibrations, which vibrant directions are perpendicular to the wave vectors of atomic beam. Compared with the detector consisting of atomic Mach-Zehnder interferometer, the new detector has two advantages: (1) it is suitable for the detection of the harmonic vibrations induced either by a longitudinal plane harmonic wave or by a transverse plane harmonic wave; (2) the quantum noise fluctuation of the atomic beam is exactly zero.

  3. Atom trapping in a bottle beam created by a diffractive optical element

    CERN Document Server

    Ivanov, V V; Saffman, M; Kemme, S A; Ellis, A R; Brady, G R; Wendt, J R; Biedermann, G W; Samora, S

    2013-01-01

    A diffractive optical element (DOE) has been fabricated for creating blue detuned atomic bottle beam traps. The DOE integrates several diffractive lenses for trap creation and imaging of atomic fluorescence. We characterize the performance of the DOE and demonstrate trapping of cold Cesium atoms inside a bottle beam.

  4. Matrix isolation sublimation: An apparatus for producing cryogenic beams of atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Sacramento, R. L.; Alves, B. X.; Silva, B. A.; Wolff, W.; Cesar, C. L. [Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972 Rio de Janeiro, RJ (Brazil); Oliveira, A. N. [Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972 Rio de Janeiro, RJ (Brazil); INMETRO, Av. Nossa Senhora das Graças, 50 25250-020 Duque de Caxias, RJ (Brazil); Li, M. S. [Instituto de Física de São Carlos, Universidade de São Paulo, Ave. Trabalhador São Carlense, 400, 13565-590 São Carlos, SP (Brazil)

    2015-07-15

    We describe the apparatus to generate cryogenic beams of atoms and molecules based on matrix isolation sublimation. Isolation matrices of Ne and H{sub 2} are hosts for atomic and molecular species which are sublimated into vacuum at cryogenic temperatures. The resulting cryogenic beams are used for high-resolution laser spectroscopy. The technique also aims at loading atomic and molecular traps.

  5. Molecular beam studies of oxide reduction by atomic hydrogen

    International Nuclear Information System (INIS)

    The graphite and oxide internals of a CTR are susceptible to chemical corrosion as well as to physical degradation by high-energy particles. Reactions of thermal atomic hydrogen with oxides are being studied. The hydrogen used is at thermal energy (0.22 eV). Typical data are reported for the H/UO2 system. The reaction probability is plotted as a function of solid temperature at fixed beam intensity and moculation frequency. The reaction probability increases from low temperature to a high-temperature plateau at about 13000C. Here the reaction rate is limited solely by the sticking probability of H on the surface; about one in seven of the incident atoms is chemisorbed by the surface and ultimately returns to the gas phase as water vapor. A reaction model comprising sticking, recombination to H2, solution and diffusion of H in the bulk of the UO2, surface reaction of adsorbed H with lattice oxygen atoms to produce the hydroxyl radical, and production of water is constructed. The rate constants for the elementary steps in the mechanism are tabulated. 2 figures, 2 tables

  6. Advancing atomic nanolithography: cold atomic Cs beam exposure of alkanethiol self-assembled monolayers

    International Nuclear Information System (INIS)

    We report the results of a study into the quality of functionalized surfaces for nanolithographic imaging. Self-assembled monolayer (SAM) coverage, subsequent post-etch pattern definition and minimum feature size all depend on the quality of the Au substrate used in atomic nanolithographic experiments. We find sputtered Au substrates yield much smoother surfaces and a higher density of {111} oriented grains than evaporated Au surfaces. A detailed study of the self-assembly mechanism using molecular resolution AFM and STM has shown that the monolayer is composed of domains with sizes typically of 5-25 nm, and multiple molecular domains can exist within one Au grain. Exposure of the SAM to an optically-cooled atomic Cs beam traversing a two-dimensional array of submicron material masks and also standing wave optical masks allowed determination of the minimum average Cs dose (2 Cs atoms per SAM molecule) and the realization of < 50 nm structures. The SAM monolayer contains many non-uniformities such as pin-holes, domain boundaries and monoatomic depressions which are present in the Au surface prior to SAM adsorption. These imperfections limit the use of alkanethiols as a resist in atomic nanolithography experiments. These studies have allowed us to realize an Atom Pencil suitable for deposition of precision quantities of material at the microand nanoscale to an active surface

  7. Novel Atomic Mirror with a Blue-Detuned Semi-Gaussian Beam

    Institute of Scientific and Technical Information of China (English)

    郑萍; 高伟建; 印建平

    2003-01-01

    A novel and simple atomic mirror composed of a blue-detuned semi-Gaussian beam is proposed. From the Fresnel diffraction theory, the intensity distributions of a collimated GaUssian laser beam diffracted by the straight edge of a semi-infinite opaque plate are studied. The optical potential of the semi-Gaussian beam for 85 Rb atoms and its spontaneous emission probability are calculated and compared with the performance of the evanescent-wave mirror. Our study shows that the blue-detuned semi-Gaussian beam, as a novel atomic mirror, can be used to reflect atomic beam efliciently, and under the same beam parameters and lower normal atomic velocity, the performance of the semi-Gaussian-beam mirror is better than that of the evanescent-wave mirror.

  8. Two-step resonance ionization spectroscopy of Na atomic beam using cw and pulsed lasers

    International Nuclear Information System (INIS)

    Two-step photoionization of sodium atomic beam has been carried out using a cw and a pulsed dye lasers. Sodium ions have been detected by a time of flight method in order to reduce background noise. With a proper power of the pulsed dye laser the sodium atomic beam has been irradiated by a resonant cw dye laser. The density of the sodium atomic beam is estimated to be 103 cm-3 at the ionization area. (author)

  9. Cold beam of isotopically pure Yb atoms by deflection using 1D-optical molasses

    OpenAIRE

    Rathod, KD; Singh, PK; Natarajan, Vasant

    2014-01-01

    We demonstrate the generation of an isotopically pure beam of laser-cooled Yb atoms by deflection using 1D-optical molasses. Atoms in a collimated thermal beam are first slowed using a Zeeman slower. They are then subjected to a pair of molasses beams inclined at 45(a similar to) with respect to the slowed atomic beam. The slowed atoms are deflected and probed at a distance of 160 mm. We demonstrate the selective deflection of the bosonic isotope Yb-174 and the fermionic isotope Yb-171. Using...

  10. A high-intensity beam of metastable helium atoms with good velocity resolution

    International Nuclear Information System (INIS)

    The excitation of a low-energy ground state helium beam to its metastable states by electron impact is analysed. It is shown that the narrowest velocity distribution for the resulting metastable helium beam is obtained by directing the helium and electron beams parallel or antiparallel. A source of metastable helium atoms was constructed according to this analysis which produced a beam of 3 x 1014 metastable atoms/s sr with a velocity resolution of 3% FWHM for a room-temperature beam (E = 66 MeV). A possible source of errors in time-of-flight experiments with metastable atoms is pointed out. (author)

  11. Preparation of a single-state atomic beam by optical pumping and radiative deflection

    International Nuclear Information System (INIS)

    A simple technique for producing a single-state sodium atomic beam is described. A single laser both optically pumps the F = 2 ground-state atoms into m/sub F/ = +2 and deflects the pumped atoms away from residual F = 1 atoms. Data demonstrating the technique are presented, and a practical design for an apparatus based on these principles is described

  12. Manipulation and analysis of atomic and molecular beams using transmission gratings and Fresnel zone plates

    Energy Technology Data Exchange (ETDEWEB)

    Grisenti, R.E.

    2000-06-01

    In this thesis experimental results on the diffraction of rare gas atoms (He, Ne, Ar, Kr) and molecular (D{sub 2}) beams by a 100 nm period transmission grating and on the focusing of a helium atom beam through a Fresnel zone plate have been reported. (orig.)

  13. SOME PROPERTIES OF ATOMIC BEAM PRODUCED BY LASER INDUCED ABLATION OF Li TARGET

    OpenAIRE

    Harnafi, M.; Dubreuil, B.

    1987-01-01

    In this experiment, pulsed atomic beams produced in vacuum by laser induced ablation from lithium target are analyzed by laser-induced fluorescsence (LIF). As an application of this atomic beam production technique, the l-mixing processes induced in the n = 9, 10 Li Rydberg states by collisions with CO2 molecules have been investigated.

  14. An atomic beam source for fast loading of a magneto-optical trap under high vacuum

    DEFF Research Database (Denmark)

    McDowall, P.D.; Hilliard, Andrew; Grünzweig, T.;

    2012-01-01

    We report on a directional atomic beam created using an alkali metal dispenser and a nozzle. By applying a high current (15 A) pulse to the dispenser at room temperature we can rapidly heat it to a temperature at which it starts dispensing, avoiding the need for preheating. The atomic beam produced...

  15. Atomic scattering from an adsorbed monolayer solid with a helium beam that penetrates to the substrate

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Bruch, L.W.; Dammann, Bernd

    2013-01-01

    Diffraction and one-phonon inelastic scattering of a thermal energy helium atomic beam are evaluated in the situation that the target monolayer lattice is so dilated that the atomic beam penetrates to the interlayer region between the monolayer and the substrate. The scattering is simulated by...

  16. 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. PMID:26922370

  17. Coherent and non coherent atom optics experiment with an ultra-narrow beam of metastable rare gas atoms

    International Nuclear Information System (INIS)

    In this thesis, we present a new type of atomic source: an ultra-narrow beam of metastable atoms produced by resonant metastability exchange inside a supersonic beam of rare gas atoms. We used the coherence properties of this beam to observe the diffraction of metastable helium, argon and neon atoms by a nano-transmission grating and by micro-reflection-gratings. Then, we evidenced transitions between Zeeman sublevels of neon metastable 3P2 state due to the quadrupolar part of Van der Waals potential. After we showed experimental proofs of the observation of this phenomenon, we calculated the transition probabilities in the Landau - Zener model. We discussed the interest of Van der Waals - Zeeman transitions for atom interferometry. Last, we described the Zeeman cooling of the supersonic metastable argon beam (3P2). We have succeeded in slowing down atoms to speeds below 100 m/s. We gave experimental details and showed the first time-of-flight measurements of slowed atoms

  18. Velocity distribution measurements in atomic beams generated using laser induced back-ablation

    CERN Document Server

    Denning, A; Lee, S; Ammonson, M; Bergeson, S D

    2008-01-01

    We present measurements of the velocity distribution of calcium atoms in an atomic beam generated using a dual-stage laser back-ablation apparatus. Distributions are measured using a velocity selective Doppler time-of-flight technique. They are Boltzmann-like with rms velocities corresponding to temperatures above the melting point for calcium. Contrary to a recent report in the literature, this method does not generate a sub-thermal atomic beam.

  19. Velocity Distribution of Effective Atoms in a Small Optically Pumped Cesium Beam Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    CHEN Jingbiao; WANG Fengzhi; YANG Donghai; WANG YiQiu

    2001-01-01

    In this paper, the velocity distribution of effective atoms in a small optically pumped cesium beam frequency standard has been achieved from the Fourier transforms of the experimentally recorded Ramsey patterns. The result fits well with the theoretical calculation. The second order Doppler shift correction of the small cesium atomic clock is obtained from the velocity distribution of effective atoms.

  20. Scattering of low-energy electrons by excited sodium atoms using a photon and electron atomic beam recoil technique

    International Nuclear Information System (INIS)

    A new method for measuring cross sections for the scattering of electrons by laser-excited atoms is described. It is a generalization of the atomic-beam recoil technique, taking advantage of the recoil of atoms during resonant photon interactions to spatially separate excited from nonexcited atoms. A preliminary value for the total cross section for the scattering of electrons by the 32P3/2(m/sub F/=3) state of sodium at 4.4 eV is presented

  1. Generation of a cold pulsed beam of Rb atoms by transfer from a 3D magneto-optic trap

    CERN Document Server

    Chanu, Sapam Ranjita; Natarajan, Vasant

    2016-01-01

    We demonstrate a technique for producing a cold pulsed beam of atoms by transferring a cloud of atoms trapped in a three dimensional magneto-optic trap (MOT). The MOT is loaded by heating a getter source of Rb atoms. We show that it is advantageous to transfer with two beams (with a small angle between them) compared to a single beam, because the atoms stop interacting with the beams in the two-beam technique, which results in a Gaussian velocity distribution. The atoms are further cooled in optical molasses by turning off the MOT magnetic field before the transfer beams are turned on.

  2. Generation of a cold pulsed beam of Rb atoms by transfer from a 3D magneto-optic trap

    Science.gov (United States)

    Chanu, Sapam Ranjita; Rathod, Ketan D.; Natarajan, Vasant

    2016-08-01

    We demonstrate a technique for producing a cold pulsed beam of atoms by transferring a cloud of atoms trapped in a three dimensional magneto-optic trap (MOT). The MOT is loaded by heating a getter source of Rb atoms. We show that it is advantageous to transfer with two beams (with a small angle between them) compared to a single beam, because the atoms stop interacting with the beams in the two-beam technique, which results in a Gaussian velocity distribution. The atoms are further cooled in optical molasses by turning off the MOT magnetic field before the transfer beams are turned on.

  3. Quantum coherent tractor beam effect for atoms trapped near a nanowaveguide

    Science.gov (United States)

    Sadgrove, Mark; Wimberger, Sandro; Nic Chormaic, Síle

    2016-01-01

    We propose several schemes to realize a tractor beam effect for ultracold atoms in the vicinity of a few-mode nanowaveguide. Atoms trapped near the waveguide are transported in a direction opposite to the guided mode propagation direction. We analyse three specific examples for ultracold 23Na atoms trapped near a specific nanowaveguide (i.e. an optical nanofibre): (i) a conveyor belt-type tractor beam effect, (ii) an accelerator tractor beam effect, and (iii) a quantum coherent tractor beam effect, all of which can effectively pull atoms along the nanofibre toward the light source. This technique provides a new tool for controlling the motion of particles near nanowaveguides with potential applications in the study of particle transport and binding as well as atom interferometry. PMID:27440516

  4. Quantum coherent tractor beam effect for atoms trapped near a nanowaveguide

    Science.gov (United States)

    Sadgrove, Mark; Wimberger, Sandro; Nic Chormaic, Síle

    2016-07-01

    We propose several schemes to realize a tractor beam effect for ultracold atoms in the vicinity of a few-mode nanowaveguide. Atoms trapped near the waveguide are transported in a direction opposite to the guided mode propagation direction. We analyse three specific examples for ultracold 23Na atoms trapped near a specific nanowaveguide (i.e. an optical nanofibre): (i) a conveyor belt-type tractor beam effect, (ii) an accelerator tractor beam effect, and (iii) a quantum coherent tractor beam effect, all of which can effectively pull atoms along the nanofibre toward the light source. This technique provides a new tool for controlling the motion of particles near nanowaveguides with potential applications in the study of particle transport and binding as well as atom interferometry.

  5. Theoretical study on isotope separation of an ytterbium atomic beam by laser deflection

    International Nuclear Information System (INIS)

    Isotope separation by laser deflecting an atomic beam is analyzed theoretically. Interacting with a tilted one-dimensional optical molasses, an ytterbium atomic beam is split into multi-beams with different isotopes like 172Yb,173Yb, and 174Yb. By using the numerical calculation, the dependences of the splitting angle on the molasses laser intensity and detuning are studied, and the optimal parameters for the isotope separation are also investigated. Furthermore, the isotope separation efficiency and purity are estimated. Finally a new scheme for the efficient isotope separation is proposed. These findings will give a guideline for simply obtaining pure isotopes of various elements. (atomic and molecular physics)

  6. High-flux beam source for cold, slow atoms or molecules

    OpenAIRE

    Maxwell, S. E.; Brahms, N.; deCarvalho, R.; Helton, J.; Nguyen, S V; Patterson, D; Doyle, J. M.; Glenn, D. R.; Petricka, J.; DeMille, D.

    2005-01-01

    We demonstrate and characterize a high-flux beam source for cold, slow atoms or molecules. The desired species is vaporized using laser ablation, then cooled by thermalization in a cryogenic cell of buffer gas. The beam is formed by particles exiting a hole in the buffer gas cell. We characterize the properties of the beam (flux, forward velocity, temperature) for both an atom (Na) and a molecule (PbO) under varying buffer gas density, and discuss conditions for optimizing these beam paramete...

  7. Application of cold beam of atoms and molecules for studying luminescence of oxygen atoms stimulated by metastable helium

    International Nuclear Information System (INIS)

    We describe a method for creating a high flux beam of cold atoms and molecules. By using this beam method, spectroscopic studies of the afterglow of oxygen-helium gas mixtures at cryogenic temperatures were performed. The cooling by helium vapor of a helium jet containing trace amounts of oxygen after passing through a radiofrequency discharge zone led to the observation of strong emissions from atomic oxygen. The effect results from the increased efficiency of energy transfer from metastable helium atoms and molecules to the atomic oxygen in the cold dense helium vapor. The effect might find application for the detection of small quantities of impurities in helium gas as well as possible laser action

  8. Development of francium atomic beam for the search of the electron electric dipole moment

    Directory of Open Access Journals (Sweden)

    Sato Tomoya

    2014-03-01

    Full Text Available For the measurement of the electron electric dipole moment using Fr atoms, a Fr ion-atom conversion is one of the most critical process. An ion-atom converter based on the “orthotropic” type of Fr source has been developed. This converter is able to convert a few keV Fr ion beam to a thermal atomic beam using a cycle of the surface ionization and neutralization. In this article, the development of the converter is reported.

  9. ATOMIC BEAM POLARIZATION MEASUREMENT OF THE RHIC POLARIZED H-JET TARGET.

    Energy Technology Data Exchange (ETDEWEB)

    MAKDISI,Y.; NASS,A.; GRAHAM,D.; KPONOU,A.; MAHLER,G.; MENG,W.; RITTER,J.; ET AL.

    2005-01-28

    The RHIC polarized H-Jet measures the polarization of the RHIC proton beam via elastic scattering off a nuclear polarized atomic hydrogen beam. The atomic beam is produced by a dissociator, a beam forming system and sextupole magnets. Nuclear polarization is achieved by exchanging occupation numbers of hyperfine states using high frequency transitions. The polarization was measured using a modified form of a Breit-Rabi polarimeter including focusing magnets and another set of high frequency transitions. The sampling of a large part of the beam and low noise electronics made it possible to measure the polarization to a high degree of accuracy in a very short time period (1 min). Using this system, we measured no depolarization of the atomic beam due to the RF fields of the bunched proton beam. Time-of-Flight measurements were done using a fast chopper and a QMA at the position of the RHIC interaction point to determine the areal density of the atomic beam seen by the RHIC beam.

  10. Chaotic dynamics of dilute thermal atom clouds on stationary optical Bessel beams

    International Nuclear Information System (INIS)

    We characterize the semiclassical dynamics of dilute thermal atom clouds located in three-dimensional optical lattices generated by stationary optical Bessel beams. The dynamics of the cold atoms is explored in the quasi-Hamiltonian regime that arises using laser beams with far-off resonance detuning. Although the transverse structure of Bessel beams exhibits a complex topological structure, it is found that the longitudinal motion along the main propagation axis of the beam is the detonator of a high sensitivity of the atoms' motion to the initial conditions. This effect would not be properly described by bidimensional models. We show that an experimental implementation can be highly simplified by an analysis of the behaviour of the dynamical system under scale transformations. Experimentally feasible signatures of the chaotic dynamics of the atom clouds are also identified. (paper)

  11. Status of the hydrogen and deuterium atomic beam polarized target for NEPTUN experiment

    Science.gov (United States)

    Balandikov, N. I.; Ershov, V. P.; Fimushkin, V. V.; Kulikov, M. V.; Pilipenko, Yu. K.; Shutov, V. B.

    1995-09-01

    NEPTUN-NEPTUN-A is a polarized experiment at Accelerating and Storage Complex (UNK, IHEP) with two internal targets. Status of the atomic beam polarized target that is being developed at the Joint Institute for Nuclear Research, Dubna is presented.

  12. Particle beam technology for control of atomic-bonding state in materials

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, Junzo [Kyoto Univ. (Japan). Faculty of Engineering

    1997-03-01

    The atomic-bonding state in materials can be controlled through `kinetic bonding` process by energetic particle beams which have a sufficient atomic kinetic energy. In order to clarify the `kinetic bonding` process the negative-ion beam deposition is considered as an ideal method because the negative ion has no additional active energies. Sputter type heavy negative-ion sources can be used for this purpose. Carbon films prepared by carbon negative-ion beam deposition have a strong dependency of the film properties on ion beam kinetic energy and have a quite high thermal conductivity which is comparable to that of the IIb diamond at a kinetic energy of 50-100 eV/atom. It suggests that new or metastable materials could be formed through the `kinetic bonding` process. Negative-ion beams can also be used for ion implantation, in which charging problems are perfectly reduced. (author)

  13. Focussing a helium atom beam by reflection from a concave surface

    International Nuclear Information System (INIS)

    Results of 1-dimensional focussing of a Helium-atom beam reflected from a concave, cylindrical surface are presented. The atomic beam is created by a supersonic expansion and collimated by a skimmer and two slits, variable in size (5-20 μm). For grazing incident angles of a few milliradian the beam is coherently reflected by quantum reflection. Beam profiles at the focus are measured by cutting off the intensity by scanning a knife edge with a piezo (analogy to waist measurement by a razor blade in laser optics). The width of the focus is limited by the source size, by spherical aberration and by diffraction effects. We tune the deBroglie-wavelength by changing the temperature of the atom beam source to see how diffraction influences the focus' width and shape. The smallest focus achieved so far is 1.0±0.1 μm

  14. Magnetic focusing of cold atomic beam with a 2D array of current-carrying wires

    Institute of Scientific and Technical Information of China (English)

    Yang Liu; Min Yun; Jianping Yin

    2006-01-01

    @@ A new scheme to realize a two-dimensional (2D) array of magnetic micro-lenses for a cold atomic beam,formed by an array of square current-carrying wires,is proposed.We calculate the spatial distributions of the magnetic fields from the array of current-carrying wires and the magnetic focusing potential for cold rubidium atoms,and study the dynamic focusing processes of cold atoms passing through the magnetic micro-lens array and its focusing properties by using Monte-Carlo simulations and trajectory tracing method.The result shows that the proposed micro-lens array can be used to focus effectively a cold atomic beam,even to load ultracold atoms or a BEC sample into a 2D optical lattice formed by blue detuned hollow beams.

  15. Manufacture of high-speed neutral atomic and molecular beam apparatus and its characterization

    International Nuclear Information System (INIS)

    Our research group has been studying chemical reactivity at solid surfaces. For example, the study of O2/Si (001) reaction dynamics has been demonstrated with a hyperthermal molecular beam technique and synchrotron radiation photoemission spectroscopy. By using more reactive atomic and molecular beams with higher kinetic energy than supersonic molecular beams, it is expected that researches on surface chemical reactivity can be progressed. For this reason, we are developing a high-speed neutral atomic and molecular beam generator. This apparatus generates ion beams with a plasma ion source. The control of kinetic energy of neutral beams is performed by accelerating and decelerating the positive ion beams. Desirable ions are selected with a Wien filter: Passing through a gas cell they are neutralized by charge transfer reactions. In this report we describe characteristics of ion beams, which are generated by using oxygen as a sample gas, as well as neutral beams. When acceleration energy was 8 keV and 20 eV, total ion beam current was 52 μA, and 17 μA respectively. Characteristics of the mass separator were good, even when ion beam energy was 20 eV. Ion beam current was 5.5 μA for O+ and 11 μA for O2+, respectively (author)

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

    International Nuclear Information System (INIS)

    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

  17. Collisions of metastable Ne*, He* atoms with ground-state He, Ne atoms studied by atomic beam and laser techniques

    International Nuclear Information System (INIS)

    A crossed nozzle-beam experiment is used to investigate thermal energy collisions: Ne* (2p53s, 3P0,2) + He(1s2, 1S0), almost purely elastic, and He*(1s2s, 1,3S + Ne(2p6, 1S0), in which inelastic excitation transfers occur. State and velocity selection of the scattered Ne* atoms is performed using a tunable cw dye laser frequency locked on a definite Zeeman component of the transition 1s5 → 2p6 (λ = 614.3 nm) of 20Ne or 22Ne. In the purely elastic case, this technique allows the selection of one of the two final velocities, and then an unambiguous transformation of the differential cross section at 62 meV tallies on accords with a calculation using a single effective potential. In He* on Ne collisions, the main inelastic processes are endothermic excitation transfers from He*(21S). Experimental results obtained at different energies (62, 95, 109, 124 meV) show that the transfers essentially result in levels 3s and 4d of Ne. (orig.)

  18. MEMS-Based Optical Beam Steering System for Quantum Information Processing in 2D Atomic Systems

    OpenAIRE

    Knoernschild, Caleb; Kim, Changsoon; Liu, Bin; Lu, Felix P.; Kim, Jungsang

    2007-01-01

    In order to provide scalability to quantum information processors utilizing trapped atoms or ions as quantum bits (qubits), the capability to address multiple individual qubits in a large array is needed. Micro-electromechanical systems (MEMS) technology can be used to create a flexible and scalable optical system to direct the necessary laser beams to multiple qubit locations. We developed beam steering optics using controllable MEMS mirrors that enable one laser beam to address multiple qub...

  19. Self-corrected sensors based on atomic absorption spectroscopy for atom flux measurements in molecular beam epitaxy

    International Nuclear Information System (INIS)

    A high sensitivity atom flux sensor based on atomic absorption spectroscopy has been designed and implemented to control electron beam evaporators and effusion cells in a molecular beam epitaxy system. Using a high-resolution spectrometer and a two-dimensional charge coupled device detector in a double-beam configuration, we employ either a non-resonant line or a resonant line with low cross section from the same hollow cathode lamp as the reference for nearly perfect background correction and baseline drift removal. This setup also significantly shortens the warm-up time needed compared to other sensor technologies and drastically reduces the noise coming from the surrounding environment. In addition, the high-resolution spectrometer allows the most sensitive resonant line to be isolated and used to provide excellent signal-to-noise ratio

  20. Engineering of hydrophilic and plasmonic properties of Ag thin film by atom beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Udai B., E-mail: udaibhansingh123@gmail.com [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, Post Box - 10502, New Delhi, 110 067 (India); Agarwal, D.C.; Khan, S.A.; Kumar, Manish; Tripathi, A.; Singhal, R. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, Post Box - 10502, New Delhi, 110 067 (India); Panigrahi, B.K. [Material Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India); Avasthi, D.K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, Post Box - 10502, New Delhi, 110 067 (India)

    2011-12-01

    Hydrophilic Ag nanostructures were synthesized by physical vapour deposition of 5 nm Ag thin films followed by irradiation with 1.5 keV Ar atoms. Optical absorbance measurements show a characteristic surface plasmon resonance absorption band in visible region. A blue-shift in absorbance from 532 to 450 nm is observed with increasing fluence from 1 Multiplication-Sign 10{sup 16} to 3 Multiplication-Sign 10{sup 16} atoms/cm{sup 2}. Atomic force microscopy was performed for the pristine and irradiated samples to study the surface morphology. The atom beam irradiation induced sputtering and surface diffusion lead to the formation of plasmonic surface. Rutherford backscattering spectroscopy of the pristine and irradiated film indicates that metal content in the film decreases with ion fluence, which is attributed to the sputtering of Ag by Ar atoms. The contact angle measurement demonstrates the possibility of engineering the hydrophilicity by atom beam irradiation.

  1. Independent individual addressing of multiple neutral atom qubits with a MEMS beam steering system

    OpenAIRE

    Knoernschild, Caleb; Zhang, Xianli L.; Isenhower, Larry; Gill, Alex T.; Lu, Felix P.; Saffman, Mark; Kim, Jungsang

    2010-01-01

    We demonstrate a scalable approach to addressing multiple atomic qubits for use in quantum information processing. Individually trapped 87Rb atoms in a linear array are selectively manipulated with a single laser guided by a MEMS beam steering system. Single qubit oscillations are shown on multiple sites at frequencies of ~3.5 MHz with negligible crosstalk to neighboring sites. Switching times between the central atom and its closest neighbor were measured to be 6-7 us while moving between th...

  2. Measurement of Pionic 121Sn atoms at the RI beam factory

    International Nuclear Information System (INIS)

    We have measured the energy spectrum of pionic 121Sn atoms by missing-mass spectroscopy of the 122Sn(d, 3He) reaction near the π − emission threshold. The measurement serves as a pilot experiment for high precision systematic spectroscopy of deeply bound pionic atoms in a new pionic Atom Factory project (piAF) at the RI beam factory (RIBF) of RIKEN. The status of the analysis is reported.

  3. Numerical Investigation Of The Bombardment Of A Graphene Sheet By A Beam Of Carbon Atoms

    Directory of Open Access Journals (Sweden)

    O.V. Khomenko

    2009-01-01

    Full Text Available Classical molecular dynamics simulations of the bombardment of a graphene sheet by a beam of carbon atoms are carried out. Covalent bonds in the irradiated sample are described by the Brenner potential. The approximation of elastic balls interacting with graphene via the Lennard-Jones potential is used for particles in a beam. The influence of the energy and density of irradiating carbon atoms and of the presence of a thermostat on physical processes occurring during the collisions with the sample is investigated. Energy values of the particles in a beam, which are enough for the sample destruction, are defined.

  4. Generation of cold low divergent atomic beam of indium by laser ablation

    International Nuclear Information System (INIS)

    The formation of low-energy (below 100 m/s), low divergence (without any collimation optics) pulsed indium atomic beam via ablation of thin film by direct illumination (unfocused) from the rear side with second harmonic of Q-switched Nd:YAG laser under high vacuum (∼10-5 Torr) is reported. Angular divergence of an ablated indium beam was measured for the different laser powers. Axial atomic and ionic velocities were studied as a function of laser energy per pulse using a beam deflection setup

  5. A two-dimensional lattice of blue detuned atom traps using a projected Gaussian beam array

    CERN Document Server

    Piotrowicz, M J; Maller, K; Li, G; Zhang, S; Isenhower, L; Saffman, M

    2013-01-01

    We describe a new type of blue detuned optical lattice for atom trapping which is intrinsically two dimensional, while providing three-dimensional atom localization. The lattice is insensitive to optical phase fluctuations since it does not depend on field interference between distinct optical beams. The array is created using a novel arrangement of weakly overlapping Gaussian beams that creates a two-dimensional array of dark traps which are suitable for magic trapping of ground and Rydberg states. We analyze the spatial localization that can be achieved and demonstrate trapping and detection of single Cs atoms in 6 and 49 site two-dimensional arrays.

  6. Proceedings of the workshop on atomic physics with fast heavy-ion beams

    International Nuclear Information System (INIS)

    The Workshop on Atomic Physics with Fast Heavy-Ion Beams was held in the Physics Division, Argonne National Laboratory on January 20 and 21, 1983. The meeting brought together approx. 50 practitioners in the field of accelerator-based atomic physics. The workshop was held to focus attention on possible areas of atomic physics research which would benefit from use of the newest generation of accelerators designed to produce intense high-quality beams of fast heavy ions. Abstracts of individual paper were prepared separately for the data base

  7. A compact design for a magnetic synchrotron to store beams of hydrogen atoms

    CERN Document Server

    van der Poel, Aernout P P; Softley, Timothy P; Bethlem, Hendrick L

    2015-01-01

    We present a design for an atomic synchrotron consisting of 40 hybrid magnetic hexapole lenses arranged in a circle. We show that for realistic parameters, hydrogen atoms with a velocity up to 600 m/s can be stored in a 1-meter diameter ring, which implies that the atoms can be injected in the ring directly from a pulsed supersonic beam source. This ring can be used to study collisions between stored hydrogen atoms and molecular beams of many different atoms and molecules. The advantage of using a synchrotron is two-fold: (i) the collision partners move in the same direction as the stored atoms, resulting in a small relative velocity and thus a low collision energy, and (ii) by storing atoms for many round-trips, the sensitivity to collisions is enhanced by a factor of 100-1000. In the proposed ring, the cross-sections for collisions between hydrogen, the most abundant atom in the universe, with any atom or molecule that can be put in a beam, including He, H$_2$, CO, ammonia and OH can be measured at energies...

  8. Beam quality of a non-ideal atom laser

    OpenAIRE

    Riou, Jean-Félix; Guerin, William; Le Coq, Yann; Fauquembergue, Marie; Bouyer, Philippe; Josse, Vincent; Aspect, Alain

    2006-01-01

    International audience We study the propagation of a non-interacting atom laser distorted by the strong lensing effect of the Bose-Einstein Condensate (BEC) from which it is outcoupled. We observe a transverse structure containing caustics that vary with the density within the residing BEC. Using WKB approximation, Fresnel-Kirchhoff integral formalism and ABCD matrices, we are able to describe analytically the atom laser propagation. This allows us to characterize the quality of the non-id...

  9. Hypervelocity supersonic nozzle beam source of atomic oxygen

    Science.gov (United States)

    Freedman, A.; Unkel, W.; Silver, J.; Kolb, C.

    1984-01-01

    A hypervelocity source of atomic oxygen was developed. Dissociation of molecular oxygen is accomplished by injection into a flow of helium and/or argon which has been heated in a commercial plasma torch. Atomic velocities of up to 4 kms(-1) were produced; recent improvements offer the possibility of even higher velocities. This source was utilized in studies of translational-to-vibrational energy transfer in carbon dioxide and in an investigation of the shuttle glow effect.

  10. Reactions of carbon atoms in pulsed molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Reisler, H. [Univ. of Southern California, Los Angeles (United States)

    1993-12-01

    This research program consists of a broad scope of experiments designed to unravel the chemistry of atomic carbon in its two spin states, P and D, by using well-controlled initial conditions and state-resolved detection of products. Prerequisite to the proposed studies (and the reason why so little is known about carbon atom reactions), is the development of clean sources of carbon atoms. Therefore, in parallel with the studies of its chemistry and reaction dynamics, the authors continuously explore new, state-specific and efficient ways of producing atomic carbon. In the current program, C({sup 3}P) is produced via laser ablation of graphite, and three areas of study are being pursued: (i) exothermic reactions with small inorganic molecules (e.g., O{sub 2}, N{sub 2}O, NO{sub 2}) that can proceed via multiple pathways; (ii) the influence of vibrational and translational energy on endothermic reactions involving H-containing reactants that yield CH products (e.g., H{sub 2}O H{sub 2}CO); (iii) reactions of C({sup 3}P) with free radicals (e.g., HCO, CH{sub 3}O). In addition, the authors plan to develop a source of C({sup 1}D) atoms by exploiting the pyrolysis of diazotetrazole and its salts in the ablation source. Another important goal involves collaboration with theoreticians in order to obtain relevant potential energy surfaces, rationalize the experimental results and predict the roles of translational and vibrational energies.

  11. Generation of slow muon beam by laser resonant ionization of muonium atoms

    International Nuclear Information System (INIS)

    We report first results of re-acceleration of thermal muons, which were generated by laser resonant ionization of muonium atoms. The re-accelerated beam (slow muon beam) has better energy resolution and space distribution compared to initial surface muon beam, and its use will extend the scope of muon spin relaxation technique from bulk material to thin film, multi-layers, surfaces and extremely small samples. The yield of slow muons obtained during the first beam time was 0.03 muons/s

  12. Development and Testing of Atomic Beam-Based Plasma Edge Diagnostics in the CIEMAT Fusion Devices

    International Nuclear Information System (INIS)

    In this report the development of plasma edge diagnostic based on atomic beam techniques fir their application in the CIEMAT fusion devices is described. The characterisation of the beams in laboratory experiments at the CSIC, together with first results in the Torsatron TJ-II are reported. Two types of beam diagnostics have been developed: a thermal (effusive) Li and a supersonic, pulsed He beams. This work has been carried out in collaboration between the institutions mentioned above under partial financial support by EURATOM. (Author) 17 refs

  13. Prospects for radiation-beam treatment of materials for atomics

    International Nuclear Information System (INIS)

    A consideration is given to various types of radiation-beam technology (ion, plasma, ion-plasma treatments, irradiation with concentrated fluxes of energy) as well as to prospects of their use for optimization of structural and phase states of reactor materials and for surface finishing. The results of corrosion tests and structural studies are presented for fuel tubes of Eh110 and Eh635 zirconium alloys and steels ChS-68, EhJ847, EhP172, EhP450, EhP753 before and after radiation-beam treatments. It is revealed that corrosion resistance and wear resistance are enhanced due to structural changes in a subsurface layer. The advantages of radiation-beam technology are noted to be ecological safety, low power consumption, high controllability and predictability of the results of action, a possibility to vary essentially the element composition and the phase state of a surface layer, as well as to form a specified surface relief. The radiation-beam technology is shown to be promising for treatment of nuclear reactor core components operating under severe conditions

  14. LOW ENERGY BEAM-GAS SPECTROSCOPY OF HIGHLY IONISED ATOMS

    OpenAIRE

    Desesquelles, J.; Denis, A.; Druetta, M.; Martin, S.

    1989-01-01

    Features of low energy beam-gas spectroscopic source are reviewed and compared to those of other light sources. Measurement techniques are surveyed. They include the study of wavelength of heavy multiply charged ions in visible and u.v. ranges from normal excited states, doubly excited states, high n levels and doubly excited Rydberg levels.

  15. Analysis of laser beam propagation effects in atomic laser isotope separation

    International Nuclear Information System (INIS)

    In the atomic laser isotope separation process, the laser beams propagate through the atomic vapor over a long distance. It has been shown that the laser-atom interactions significantly modify the laser pulse shape and propagation velocity, resulting in degradation of the isotope separation efficiency. These propagation effects have been analyzed quantitatively, and a simple scaling formula has been derived to estimate the necessary laser energy for such optically thick atomic vapor. The optimum conditions of incident laser pulse have also been discussed. (author)

  16. Cold atoms gyroscope: limits on the stability and the accuracy due to the atomic beam splitters

    International Nuclear Information System (INIS)

    This thesis present the study of a cold atoms gyroscope based on atom interferometry. The interferometer used cold cesium atoms which are manipulated with stimulated Raman transitions. The improvement of the experimental setup have allowed to reach a sensitivity similar to the best optical fiber gyroscope. Especially, we characterized the performances bring about a new Raman laser design and the atom detection system. In addition, we have studied spurious phase shifts induced by the Raman interactions and have shown they are the main limitation for the long term stability and the accuracy. (author)

  17. CO/sub 2/ laser sustained CW discharge atomic beam source

    International Nuclear Information System (INIS)

    A high pressure, supersonic, laser sustained plasma nozzle beam source has been developed for the production of intense (>1019 particles s1-sr-1) beams of atomic and/or radical species having kinetic energies in the range of 1 to 10 eV. A high plasma temperature (10 to 30,000 K) is produced in the throat of a hydrodynamic expansion nozzle by sustaining a cw optical discharge in a gas using a high power cw CO2 laser. Gas mixtures are expanded through the nozzle/discharge region creating energetic atoms and molecules. An oxygen atom beam has been produced with a kinetic energy of 2 to 3 eV and an intensity of approx. 1018 O-atoms s-1sr-1. O-atom collisions (1 eV) from an uncharacterized nickel surface shows strong specular scattering with approximately 50% energy loss to the surface. Argon beams having kinetic energies between 5 to 10 eV with intensities of >1019 atoms s-1sr-1 have also been produced. 13 refs., 8 figs

  18. Efficient sub-Doppler transverse laser cooling of an indium atomic beam

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae-Ihn

    2009-07-23

    Laser cooled atomic gases and atomic beams are widely studied samples in experimental research in atomic and optical physics. For the application of ultra cold gases as model systems for e.g. quantum many particle systems, the atomic species is not very important. Thus this field is dominated by alkaline, earthalkaline elements which are easily accessible with conventional laser sources and have convenient closed cooling transition. On the other hand, laser cooled atoms may also be interesting for technological applications, for instance for the creation of novel materials by atomic nanofabrication (ANF). There it will be important to use technologically relevant materials. As an example, using group III atoms of the periodical table in ANF may open a route to generate fully 3D structured composite materials. The minimal requirement in such an ANF experiment is the collimation of an atomic beam which is accessible by one dimensional laser cooling. In this dissertation, I describe transverse laser cooling of an Indium atomic beam. For efficient laser cooling on a cycling transition, I have built a tunable, continuous-wave coherent ultraviolet source at 326 nm based on frequency tripling. For this purpose, two independent high power Yb-doped fiber amplifiers for the generation of the fundamental radiation at {lambda}{sub {omega}} = 977 nm have been constructed. I have observed sub-Doppler transverse laser cooling of an Indium atomic beam on a cycling transition of In by introducing a polarization gradient in the linear-perpendicular-linear configuration. The transverse velocity spread of a laser-cooled In atomic beam at full width at half maximum was achieved to be 13.5{+-}3.8 cm/s yielding a full divergence of only 0.48 {+-} 0.13 mrad. In addition, nonlinear spectroscopy of a 3-level, {lambda}-type level system driven by a pump and a probe beam has been investigated in order to understand the absorption line shapes used as a frequency reference in a previous two

  19. Efficient sub-Doppler transverse laser cooling of an indium atomic beam

    International Nuclear Information System (INIS)

    Laser cooled atomic gases and atomic beams are widely studied samples in experimental research in atomic and optical physics. For the application of ultra cold gases as model systems for e.g. quantum many particle systems, the atomic species is not very important. Thus this field is dominated by alkaline, earthalkaline elements which are easily accessible with conventional laser sources and have convenient closed cooling transition. On the other hand, laser cooled atoms may also be interesting for technological applications, for instance for the creation of novel materials by atomic nanofabrication (ANF). There it will be important to use technologically relevant materials. As an example, using group III atoms of the periodical table in ANF may open a route to generate fully 3D structured composite materials. The minimal requirement in such an ANF experiment is the collimation of an atomic beam which is accessible by one dimensional laser cooling. In this dissertation, I describe transverse laser cooling of an Indium atomic beam. For efficient laser cooling on a cycling transition, I have built a tunable, continuous-wave coherent ultraviolet source at 326 nm based on frequency tripling. For this purpose, two independent high power Yb-doped fiber amplifiers for the generation of the fundamental radiation at λω = 977 nm have been constructed. I have observed sub-Doppler transverse laser cooling of an Indium atomic beam on a cycling transition of In by introducing a polarization gradient in the linear-perpendicular-linear configuration. The transverse velocity spread of a laser-cooled In atomic beam at full width at half maximum was achieved to be 13.5±3.8 cm/s yielding a full divergence of only 0.48 ± 0.13 mrad. In addition, nonlinear spectroscopy of a 3-level, Λ-type level system driven by a pump and a probe beam has been investigated in order to understand the absorption line shapes used as a frequency reference in a previous two-color spectroscopy experiment

  20. Precision atomic physics techniques for nuclear physics with radioactive beams

    OpenAIRE

    Blaum, Klaus; Dilling, Jens; Nörtershäuser, Wilfried

    2013-01-01

    Atomic physics techniques for the determination of ground-state properties of radioactive isotopes are very sensitive and provide accurate masses, binding energies, Q-values, charge radii, spins, and electromagnetic moments. Many fields in nuclear physics benefit from these highly accurate numbers. They give insight into details of the nuclear structure for a better understanding of the underlying effective interactions, provide important input for studies of fundamental symmetries in physics...

  1. Laser spectroscopy of atomic beams of short-lived nuclei

    International Nuclear Information System (INIS)

    A possibility of performing laser-nuclear-spectroscopic experiments at qualitatively new level aimed to solve the second-glass current problem and to search T-non invariant effects in the beta-decay of atomic nuclei is discussed. The question of the increase in efficiency of the experiments, aimed to study the main characteristics of nuclei, far from the beta-stability, by means of the laser spectroscopy methods is considered. 147 refs.; 5 figs.; 1 tab

  2. High flux cold Rubidium atomic beam for strongly coupled Cavity QED

    CERN Document Server

    Roy, Basudev

    2012-01-01

    This paper presents a setup capable of producing a high-flux continuous beam of cold rubidium atoms for cavity QED experiments in the regime of strong coupling. A 2 $D^+$ MOT, loaded by rubidium getters in a dry film coated vapor cell, fed a secondary moving-molasses MOT (MM-MOT) at a rate of 1.5 x $10^{10}$ atoms/sec. The MM-MOT provided a continuous beam with tunable velocity. This beam was then directed through the waist of a 280 $\\mu$m cavity resulting in a Rabi splitting of more than +/- 10 MHz. The presence of sufficient number of atoms in the cavity mode also enabled splitting in the polarization perpendicular to the input. The cavity was in the strong coupling regime, with parameters (g, $\\kappa$, $\\gamma$)/2$\\pi$ equal to (7, 3, 6)/ 2$\\pi$ MHz.

  3. Production of a 'natural' metastable nozzle beam: Van der Waals Zeeman atomic levels near a metal surface

    Science.gov (United States)

    Karam, J.-C.; Grucker, J.; Boustimi, M.; Bocvarski, V.; Vassilev, G.; Reinhardt, J.; Mainos, C.; Perales, F.; Baudon, J.; Robert, J.; Ducloy, Martial

    2005-01-01

    A method for obtaining a metastable atom beam with properties near to those of a ground state supersonic beam is demonstrated. Calculations on m sublevels of metastable argon near a metal surface are then presented.

  4. Radioactive ion beam transportation for the fundamental symmetry study with laser-trapped atoms

    Science.gov (United States)

    Arikawa, Hiroshi; Ando, S.; Aoki, T.; Ezure, S.; Harada, K.; Hayamizu, T.; Inoue, T.; Ishikawa, T.; Itoh, M.; Kawamura, H.; Kato, K.; Kato, T.; Uchiyama, A.; Aoki, T.; Furukawa, T.; Hatakeyama, A.; Hatanaka, K.; Imai, K.; Murakami, T.; Nataraj, H. S.; Sato, T.; Shimizu, Y.; Wakasa, T.; Yoshida, H. P.; Sakemi, Y.

    2014-02-01

    The search for the violation of the fundamental symmetry in a radioactive atom is the promising candidate for precision tests of the standard model and its possible extensions. The subtle signal arising from the symmetry violation is enhanced in heavy atoms, such as a francium (Fr). To realize high precision measurements, a large amount of radioactive isotopes is required. The Fr is produced via a nuclear fusion reaction using a melted gold target with a 18O primary beam at Cyclotron and Radioisotope Center, Tohoku University. The maximum extraction efficiency of the Fr ion was achieved at approximately 35%. The beam line consists of an electrostatic deflector, three electrostatic quadrupole triplets to the measurement area at 10 m away from the reaction point, and several beam diagnosis systems. We optimized parameters of the beam line.

  5. Confinement of ultracold atoms in a Laguerre-Gaussian laser beam created with diffractive optics

    CERN Document Server

    Kennedy, Sharon A; Farrar, J Tom; Akin, T G; Krzyzewski, S; Abraham, E R I

    2013-01-01

    We report 2D confinement of Rb 87 atoms in a Laguerre-Gaussian laser beam. Changing of the sign of the detuning from the atomic resonance dramatically alters the geometry of the confinement. With the laser detuned to the blue, the atoms are confined to the dark, central node of the Laguerre-Gaussian laser mode. This trapping method leads to low ac Stark shifts to the atomic levels. Alternatively, by detuning the laser to the red of the resonance, we confine atoms to the high intensity outer ring in a multiply-connected, toroidal configuration. We model the confined atoms to determine azimuthal intensity variations of the trapping laser, caused by slight misalignments of the Laguerre-Gaussian mode generating optics.

  6. Intense Electron Beams from GaAs Photocathodes as a Tool for Molecular and Atomic Physics

    OpenAIRE

    Krantz, C.

    2009-01-01

    We present cesium-coated GaAs photocathodes as reliable sources of intense, quasi-monoenergetic electron beams in atomic and molecular physics experiments. In long-time operation of the Electron Target of the ion storage ring TSR in Heidelberg, cold electron beams could be realised at steadily improving intensity and reliability. Minimisation of processes degrading the quantum efficiency allowed to increase the extractable current to more than 1mA at stable cathode lifetimes of 24 h or more. ...

  7. Laser beam propagation effects in atomic laser isotope separation

    International Nuclear Information System (INIS)

    The propagation of two different-color laser pulses in the resonant three-level medium is studied. The three-level Bloch-Maxwell equations are solved numerically to analyze the change of the pulse shapes and the time-varying atomic populations. The pulse delay and the pulse shape break-up are observed especially for the first excitation laser pulse. Complete separation of the two laser pulses occur from a certain critical distance. It is shown that the rapid decrease of the ionization efficiency is caused by the separation of the two laser pulses. (author)

  8. Laser cooling of a magnetically guided ultra cold atom beam

    OpenAIRE

    Aghajani-Talesh, Anoush

    2014-01-01

    In dieser Dissertation werden zwei komplementäre Methoden für die Laserkühlung eines magnetisch geführten, ultrakalten Atomstrahls untersucht. Kombiniert könnten diese Methoden den Ausgangspunkt für eine, möglicherweise sogar kontinuierliche, Hochdurchsatzproduktion von Bose-Einstein-Kondensaten darstellen. Als erstes wird ein Mechanismus vorgestellt, mit dem sich ultrakalte Atome aus einem magnetisch geführten Atomstrahl in eine optische Dipolfalle umladen lassen. Es wird ein kontinuierli...

  9. Plasma heating simulation in the T-11 device on the neutral atom beam injection

    International Nuclear Information System (INIS)

    Calculations of the energy balance in the tokamak with injection of hot atom beams are carried out. Considered are atom ionization and capture of the produced ones as well as the transmission of energy to plasma. Energy losses on recharging are taken into account. Given are temperature dependencies on injection power, plasma density and other parameters. A possibility to obtain collisionless regime by ions is described

  10. Precision measurement of transverse velocity distribution of a strontium atomic beam

    OpenAIRE

    F. Gao; Liu, H.; P. Xu; Tian, X.; Y Wang; Ren, J; Haibin Wu; Hong Chang

    2014-01-01

    We measure the transverse velocity distribution in a thermal Sr atomic beam precisely by velocity-selective saturated fluorescence spectroscopy. The use of an ultrastable laser system and the narrow intercombination transition line of Sr atoms mean that the resolution of the measured velocity can reach 0.13 m/s, corresponding to 90$\\mu K$ in energy units. The experimental results are in very good agreement with the results of theoretical calculations. Based on the spectroscopic techniques use...

  11. Time-of-flight measurements in atomic beam devices using adiabatic high frequency transitions and sextupole magnets

    International Nuclear Information System (INIS)

    Atomic beam devices are frequently equipped with sextupole magnets to focus the beam or to act as spin filters in combination with RF-transitions for manipulating the hyperfine population within the atomic beam. A useful tool for the analysis of sextupole systems, the application of time-of-flight (TOF) measurements is presented. TOF measurements are enabled without mechanical beam chopper by utilizing adiabatic radio frequency transitions to select atoms within a certain time interval. This method is especially interesting for the use in atomic beam devices that are already equipped with RF-transitions and sextupole magnets and where space limitations or the required quality of the vacuum do not allow the installation of a mechanical chopper. The measurements presented here were performed with the atomic beam polarimeter of the HERMES polarized deuterium target and the results have been used to optimize the sextupole system of the polarimeter

  12. Crossed-molecular-beams reactive scattering of oxygen atoms

    International Nuclear Information System (INIS)

    The reactions of O(3P) with six prototypical unsaturated hydrocarbons, and the reaction of O(1D) with HD, have been studied in high-resolution crossed-molecular-beams scattering experiments with mass-spectrometric detection. The observed laboratory-product angular and velocity distributions unambiguously identify parent-daughter ion pairs, distinguish different neutral sources of the same ion, and have been used to identify the primary products of the reactions. The derived center-of-mass product angular and translational energy distributions have been used to elucidate the detailed reaction dynamics. These results demonstrate that O(3P)-unsaturated hydrocarbon chemistry is dominated by single bond cleavages, leading to radical products exclusively

  13. New atomic beam studies at low energies. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Neynaber, R.H.; Rutherford, J.A.; Vroom, D.A.

    1975-10-08

    Final cross sections have been obtained for charge transfer between the ions O/sup +/ and N/sup +/ and the neutral atoms uranium and thorium. In the course of these measurements, cross sections were also obtained for some of the other charge transfer reactions. A second task completed was the measurement of cross sections for the reaction of Al/sup +/ with molecular nitrogen and oxygen. Attempts were made to measure cross sections for other processes involving these reactants, but no measurable signals could be detected. A final set of experiments involved a search for a route for formation of H/sub 3/O/sup +/ using NO/sup +/ as a precursor. No conclusive evidence for such a process could be found in the energy range covered by the experiments. (GRA)

  14. Nonlinear dynamic response of cantilever beam tip during atomic force microscopy (AFM) nanolithography of copper surface

    International Nuclear Information System (INIS)

    This paper investigates the nonlinear dynamic response of an atomic force microscope (AFM) cantilever beam tip during the nanolithography of a copper (Cu) surface using a high-depth feed. The dynamic motion of the tip is modeled using a combined approach based on Newton's law and empirical observations. The cutting force is determined from experimental observations of the piling height on the Cu surface and the rotation angle of the cantilever beam tip. It is found that the piling height increases linearly with the cantilever beam carrier velocity. Furthermore, the cantilever beam tip is found to execute a saw tooth motion. Both this motion and the shear cutting force are nonlinear. The elastic modulus in the y direction is variable. Finally, the velocity of the cantilever beam tip as it traverses the specimen surface has a discrete characteristic rather than a smooth, continuous profile

  15. Reaction Mechanism of Oxygen Atoms with Unsaturated Hydrocarbons by the Crossed-Molecular-Beams Method

    Science.gov (United States)

    Buss, R. J.; Baseman, R. J.; Guozhong, H.; Lee, Y. T.

    1982-04-01

    From a series of studies of the reaction of oxygen atoms with unsaturated hydrocarbons using the crossed molecular beam method, the dominant reaction mechanisms were found to be the simple substitution reactions with oxygen atoms replacing H, Cl, Br atom or alkyl groups. Complication due to secondary reaction was avoided by carrying out experiments under single collisions and observing primary products directly. Primary products were identified by measuring the angular and velocity distributions of products at all the mass numbers which could be detected by the mass spectrometer, and from comparison of these distributions, applying the requirement of energy and momentum conservation.

  16. Generation of energetic He atom beams by a pulsed positive corona discharge

    OpenAIRE

    Lo, Shui-Yin; Lobo, Julio D.; Blumberg, Seth; Dibble, Theodore S.; Zhang, Xu; Tsao, Chun-Cheng; Okumura, Mitchio

    1997-01-01

    Time-of-flight measurements were made of neutral helium atom beams extracted from a repetitive, pulsed, positive-point corona discharge. Two strong neutral peaks, one fast and one slow, were observed, accompanied by a prompt photon peak and a fast ion peak. All peaks were correlated with the pulsing of the discharge. The two types of atoms appear to be formed by different mechanisms at different stages of the corona discharge. The fast atoms had energies of 190 eV and were formed at the onset...

  17. New diagnostic technique for Zeeman-compensated atomic beam slowing: technique and results

    OpenAIRE

    Molenaar, P.A.; Van Der Straten, P.; Heideman, H.G.M.; Metcalf, H.

    2001-01-01

    We have developed a new diagnostic tool for the study of Zeeman-compensated slowing of an alkali atomic beam. Our time-of-flight technique measures the longitudinal veloc- ity distribution of the slowed atoms with a resolution below the Doppler limit of 30 cm/s. Furthermore, it can map the position and velocity distribution of atoms in either ground hyperfine level inside the solenoid without any devices inside the solenoid. The technique reveals the optical pumping ef- fects, and shows in de...

  18. Application of droplet evaporation model to the expansion cooling of an atomic uranium beam

    International Nuclear Information System (INIS)

    By using the technique of laser induced fluorescence to measure the velocity distribution function of an atomic uranium beam produced by evaporation from a spherical surface by electron bombardment, we have observed the phenomenon of vapour expansion cooling. Agreement between the theoretical analysis and experimental results is satisfactory. (author)

  19. Crossed molecular beam study of H and D atom reactions with NO2

    International Nuclear Information System (INIS)

    The experimental details and results of molecular beam studies of the reactions of H and D atoms with NO2 (with an observed isotope effect of the differential cross section) with much improved sensitivity and resolution, in good agreement with earlier results of the authors, are briefly summerized. (HK)

  20. Polarized Atomic Hydrogen Beam Tests in the Mark-II Ultra-Cold Jet Target.

    Science.gov (United States)

    Luppov, V. G.; Blinov, B. B.; Gladycheva, S. E.; Kageya, T.; Kantsyrev, D. Yu.; Krisch, A. D.; Murray, J. R.; Neumann, J. J.; Raymond, R. S.; Borisov, N. S.; Kleppner, D.; Davidenko, A. M.; Grishin, V. N.

    2000-04-01

    To study spin effects in high energy collisions, we are developing an ultra-cold high-density jet target of proton-spin-polarized hydrogen atoms (Mark-II). The target uses a 12 Tesla magnetic field and a 0.3 K separation cell coated with superfluid helium-4 to produce a slow monochromatic electron-spin-polarized atomic hydrogen beam; an rf transition unit then converts this into a proton-spin-polarized beam, which is focused by a superconducting sextupole into the interaction region. Recently, the Jet produced a measured electron-spin-polarized atomic hydrogen beam of about 10^15 H s-1 into a 0.3 cm^2 area at the detector. This intensity corresponds to the free jet density of about 10^11 H cm-3 with a proton polarization of about 50%. So far, the intensity is limited by the high insulation vacuum pressure due to the evaporation of the separation cell's helium film. The beam's angular and radial distributions were measured. A test of a new superfluid-^4He-coated parabolic mirror, attached to the separation cell, appeared to increase the beam intensity by a factor of about 3, as expected.

  1. Radiation forces on a three-level atom in the high-order Bessel beams

    Institute of Scientific and Technical Information of China (English)

    Wang Zheng-Ling; Yin Jian-Ping

    2008-01-01

    The general expressions of the average dissipative and dipole forces acting on a A-configuration three-level atom in an arbitrary light field are derived by means of the optical Bloch equations based on the atomic density matrix elements, and the general properties of the average dissipative and dipole forces on a three-level atom in the linearly-polarized high-order Bessel beams (HBBs) are analysed. We find a resonant property (with two resonant peaks) of the dissipative force and a non-resonant property (with two pairs of non-resonant peaks) of the dipole force on the three-level atom, which are completely different from those on the two-level atom. Meanwhile we find a saturation effect of the average dissipative force in the HBB, which comes from the saturation of the upper-level population. Our study shows that the general expressions of the average dissipative and dipole forces on the three-level atom will be simplified to those of the two-level atom under the approximation of large detuning. Finally, we study the axial and azimuthal Doppler cooling of atoms in 1D optical molasses composed of two counter-propagating HBBs and discuss the azimuthal influence of the HBB on the Doppler cooling limit. We also find that the Doppler limit of atoms in the molasses HBB is slightly below the conventional Doppler limit of hг/(2кB) due to the orbital angular momentum lh of the HBB.

  2. Atomic beam magnetic resonance apparatus for systematic measurement of hyperfine structure anomalies (Bohr-Weisskopf effect)

    International Nuclear Information System (INIS)

    An atomic beam magnetic resonance (ABMR) apparatus has been constructed at Orsay, and has been installed at the CERN PS Booster ISOLDE mass separator facility for 'on-line' work with radioactive isotopes in a program to measure hyperfine structure anomalies (the Bohr-Weisskopf effect) over long isotopic chains. The hfs anomalies result from the effect of the spatial distribution of the nuclear magnetization on the atomic hfs interaction. Constructional details of the system are described: Emphasis is placed on the measurement of nuclear g-factors by a triple resonance, laser state selected, ABMR method. A precision better than 10-4 for gI values has been obtained in stable atomic beam tests, leading to hfs anomaly measurements better than 10%. Two types of detection systems are described: Laser fluorescence and surface ionization coupled with mass spectrometry. (orig.)

  3. Nonlinear effects in optical pumping of a cold and slow atomic beam

    KAUST Repository

    Porfido, N.

    2015-10-12

    By photoionizing hyperfine (HF) levels of the Cs state 62P3/2 in a slow and cold atom beam, we find how their population depends on the excitation laser power. The long time (around 180μs) spent by the slow atoms inside the resonant laser beam is large enough to enable exploration of a unique atom-light interaction regime heavily affected by time-dependent optical pumping. We demonstrate that, under such conditions, the onset of nonlinear effects in the population dynamics and optical pumping occurs at excitation laser intensities much smaller than the conventional respective saturation values. The evolution of population within the HF structure is calculated by numerical integration of the multilevel optical Bloch equations. The agreement between numerical results and experiment outcomes is excellent. All main features in the experimental findings are explained by the occurrence of “dark” and “bright” resonances leading to power-dependent branching coefficients.

  4. Angular correlation measurements in a thermal beam of H^* (2s) atoms using a Stern-Gerlach atomic axicon

    Science.gov (United States)

    Robert, J.; Miniatura, Ch.; Chormaic, S. Nic; Lawson-Daku, J.; Gorceix, O.; Perales, F.; Baudon, J.

    1994-11-01

    The effect of transverse magnetic gradients in Stern-Gerlach atom interferometry is to make interfere plane waves the momenta of which differ in their directions. As a result the contrast of the interference pattern produced by the longitudinal gradient is attenuated by an angular auto-correlation function in the momentum space. This effect is studied experimentally on a thermal beam of metastable H^* (2s) atoms, with a radial transverse gradient (atomic “axicon”). L'effet de gradients magnétiques transverses en interférométrie atomique de type Stern-Gerlach est de faire interférer des ondes planes ayant initialement des vecteurs d'onde différant par leurs directions. Il en résulte que, dans le signal d'interférences induit par le gradient longitudinal, le contraste est atténué par une fonction d'autocorrélation angulaire. Cet effet est étudié expérimentalement sur un jet thermique d'atomes métastables H^* (2s), dans le cas d'un gradient transverse radial (“axicon” atomique).

  5. Trapping atoms in a bottle beam generated by a diffractive optical element

    Science.gov (United States)

    Ivanov, V.; Isaacs, J.; Saffman, M.; Kemme, S. A.; Brady, G. R.; Ellis, A. R.; Wendt, J. R.

    2012-06-01

    Highly excited Rydberg states have been used to demonstrate a neutral atom quantum gate, two-atom entanglement and hold promise for studies of surface potentials, such as the Casimir-Polder potential. Blue detuned Optical Bottle Beam (BoB) traps where atoms are confined in intensity minima trap both ground and Rydberg state atoms. This minimizes qubit decoherence and allows accurate measurements of the frequencies of the Rydberg transitions. We have generated optical bottle beam traps using a segmented diffractive optical element with π phase shift between the inner and outer regions. The idea for this trap follows the approach used by Ozeri, et al. Phys. Rev. A 59, R1750 (1999) but integrates the phase shift and focusing lens into a single diffractive element fabricated at Sandia National Lab. Measured profiles of the trap light intensity are compared with numerical predictions using a Fresnel diffraction code. Progress towards atom trapping in the bottle for studies of atom-surface interactions will be presented.

  6. Detection of atomic force microscopy cantilever displacement with a transmitted electron beam

    Science.gov (United States)

    Wagner, R.; Woehl, T. J.; Keller, R. R.; Killgore, J. P.

    2016-07-01

    The response time of an atomic force microscopy (AFM) cantilever can be decreased by reducing cantilever size; however, the fastest AFM cantilevers are currently nearing the smallest size that can be detected with the conventional optical lever approach. Here, we demonstrate an electron beam detection scheme for measuring AFM cantilever oscillations. The oscillating AFM tip is positioned perpendicular to and in the path of a stationary focused nanometer sized electron beam. As the tip oscillates, the thickness of the material under the electron beam changes, causing a fluctuation in the number of scattered transmitted electrons that are detected. We demonstrate detection of sub-nanometer vibration amplitudes with an electron beam, providing a pathway for dynamic AFM with cantilevers that are orders of magnitude smaller and faster than the current state of the art.

  7. Guiding ultraslow weak-light bullets with Airy beams in a coherent atomic system

    CERN Document Server

    Hang, Chao

    2014-01-01

    We investigate the possibility of guiding stable ultraslow weak-light bullets by using Airy beams in a cold, lifetime-broadened four-level atomic system via electromagnetically induced transparency (EIT). We show that under EIT condition the light bullet with ultraslow propagating velocity and extremely low generation power formed by the balance between diffraction and nonlinearity in the probe field can be not only stabilized but also steered by the assisted field. In particular, when the assisted field is taken to be an Airy beam, the light bullet can be trapped into the main lobe of the Airy beam, propagate ultraslowly in longitudinal direction, accelerate in transverse directions, and move along a parabolic trajectory. We further show that the light bullet can bypass an obstacle when guided by two sequential Airy beams. A technique for generating ultraslow helical weak-light bullets is also proposed.

  8. The polarized H and D atomic beam source for ANKE at COSY-Jülich

    International Nuclear Information System (INIS)

    A polarized atomic beam source was developed for the polarized internal storage-cell gas target at the magnet spectrometer ANKE of COSY-Jülich. The intensities of the beams injected into the storage cell, measured with a compression tube, are 7.5×1016 hydrogen atoms/s (two hyperfine states) and 3.9×1016 deuterium atoms/s (three hyperfine states). For the hydrogen beam the achieved vector polarizations are pz≈±0.92. For the deuterium beam, the obtained combinations of vector and tensor (pzz) polarizations are pz≈±0.90 (with a constant pzz≈+0.86), and pzz=+0.90 or pzz=−1.71 (both with vanishing pz). The paper includes a detailed technical description of the apparatus and of the investigations performed during the development. This source has been very successfully used for single and double polarization measurements at ANKE as well as for studies of the polarization of recombining hydrogen molecules

  9. The Polarized H and D Atomic Beam Source for ANKE at COSY-J\\"ulich

    CERN Document Server

    Mikirtychyants, M; Grigoryev, K; Kleines, H; Kravtsov, P; Lorenz, S; Nekipelov, M; Nelyubin, V; Rathmann, F; Sarkadi, J; Schieck, H Paetz gen; Seyfarth, H; Steffens, E; Ströher, H; Vasilyev, A

    2013-01-01

    A polarized atomic beam source was developed for the polarized internal storage-cell gas target at the magnet spectrometer ANKE of COSY-J\\"ulich. The intensities of the beams injected into the storage cell, measured with a compression tube, are $7.5\\cdot 10^{16}$ hydrogen atoms/s (two hyperfine states) and $3.9\\cdot 10^{16}$ deuterium atoms/s (three hyperfine states). For the hydrogen beam the achieved vector polarizations are $p_{\\rm z}\\approx\\pm0.92$. For the deuterium beam, the obtained combinations of vector and tensor ($p_{\\rm zz}$) polarizations are $p_{\\rm z}\\approx\\pm 0.90$ (with a constant $p_{\\rm zz}\\approx +0.86$), and $p_{\\rm zz}=+0.90$ or $p_{\\rm zz}=-1.71$ (both with vanishing $p_{\\rm z}$). The paper includes a detailed technical description of the apparatus and of the investigations performed during the development.

  10. High-flux cold rubidium atomic beam for strongly-coupled cavity QED

    International Nuclear Information System (INIS)

    This paper presents a setup capable of producing a high-flux continuous beam of cold rubidium atoms for cavity quantum electrodynamics experiments in the region of strong coupling. A 2D+ magneto-optical trap (MOT), loaded with rubidium getters in a dry-film-coated vapor cell, fed a secondary moving-molasses MOT (MM-MOT) at a rate greater than 2 x 1010 atoms/s. The MM-MOT provided a continuous beam with a tunable velocity. This beam was then directed through the waist of a cavity with a length of 280 μm, resulting in a vacuum Rabi splitting of more than ±10 MHz. The presence of a sufficient number of atoms in the cavity mode also enabled splitting in the polarization perpendicular to the input. The cavity was in the strong coupling region, with an atom-photon dipole coupling coefficient g of 7 MHz, a cavity mode decay rate κ of 3 MHz, and a spontaneous emission decay rate γ of 6 MHz.

  11. High-flux cold rubidium atomic beam for strongly-coupled cavity QED

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Basudev [Indian Institute of Science Education and Research, Kolkata (India); University of Maryland, MD (United States); Scholten, Michael [University of Maryland, MD (United States)

    2012-08-15

    This paper presents a setup capable of producing a high-flux continuous beam of cold rubidium atoms for cavity quantum electrodynamics experiments in the region of strong coupling. A 2D{sup +} magneto-optical trap (MOT), loaded with rubidium getters in a dry-film-coated vapor cell, fed a secondary moving-molasses MOT (MM-MOT) at a rate greater than 2 x 10{sup 10} atoms/s. The MM-MOT provided a continuous beam with a tunable velocity. This beam was then directed through the waist of a cavity with a length of 280 μm, resulting in a vacuum Rabi splitting of more than ±10 MHz. The presence of a sufficient number of atoms in the cavity mode also enabled splitting in the polarization perpendicular to the input. The cavity was in the strong coupling region, with an atom-photon dipole coupling coefficient g of 7 MHz, a cavity mode decay rate κ of 3 MHz, and a spontaneous emission decay rate γ of 6 MHz.

  12. New source of MeV negative ion and neutral atom beams

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-02-15

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

  13. Collimation of a thulium atomic beam by two-dimensional optical molasses

    International Nuclear Information System (INIS)

    The number of laser cooled and trapped thulium atoms in a magneto-optical trap is increased by a factor of 3 using a two-dimensional optical molasses which collimated the atomic beam before entering a Zeeman slower. A diode laser operating at 410.6 nm was employed to form optical molasses: The laser was heated to 70 °C by a two-step temperature stabilisation system. The laser system consisting of a master oscillator and an injection-locked amplifier emitted more than 100 mW at 410 nm and had a spectral linewidth of 0.6 MHz. (extreme light fields and their applications)

  14. Collimation of a thulium atomic beam by two-dimensional optical molasses

    Science.gov (United States)

    Sukachev, D. D.; Kalganova, E. S.; Sokolov, A. V.; Savchenkov, A. V.; Vishnyakova, G. A.; Golovizin, A. A.; Akimov, A. V.; Kolachevsky, Nikolai N.; Sorokin, Vadim N.

    2013-04-01

    The number of laser cooled and trapped thulium atoms in a magneto-optical trap is increased by a factor of 3 using a two-dimensional optical molasses which collimated the atomic beam before entering a Zeeman slower. A diode laser operating at 410.6 nm was employed to form optical molasses: The laser was heated to 70 °C by a two-step temperature stabilisation system. The laser system consisting of a master oscillator and an injection-locked amplifier emitted more than 100 mW at 410 nm and had a spectral linewidth of 0.6 MHz.

  15. Collimation of a thulium atomic beam by two-dimensional optical molasses

    Energy Technology Data Exchange (ETDEWEB)

    Sukachev, D D; Kalganova, E S; Sokolov, A V; Savchenkov, A V; Vishnyakova, G A; Golovizin, A A; Akimov, A V; Kolachevsky, Nikolai N; Sorokin, Vadim N

    2013-04-30

    The number of laser cooled and trapped thulium atoms in a magneto-optical trap is increased by a factor of 3 using a two-dimensional optical molasses which collimated the atomic beam before entering a Zeeman slower. A diode laser operating at 410.6 nm was employed to form optical molasses: The laser was heated to 70 Degree-Sign C by a two-step temperature stabilisation system. The laser system consisting of a master oscillator and an injection-locked amplifier emitted more than 100 mW at 410 nm and had a spectral linewidth of 0.6 MHz. (extreme light fields and their applications)

  16. Precision measurement of transverse velocity distribution of a Strontium atomic beam

    CERN Document Server

    Gao, F; Xu, P; Tian, X; Wang, Y; Ren, J; Wu, Haibin; Chang, Hong

    2013-01-01

    We measure precisely the transverse velocity distribution in a thermal Sr atomic beam with a velocity selective saturated fluorescence spectroscopy. By using the ultrastable laser system and narrow intercombination transition line of Sr atoms, the resolution of the velocity measured can be reached 0.13m/s, corresponding to 90$\\mu K$ in energy unit. The experimental results are agreement very well with a theoretical calculation. With the spectroscopic techniques, the absolute frequency of the intercombination transition of $^{88}$Sr is measured by an optical-frequency comb generator referenced to the SI second through an H maser, which is given by 434 829 121 318(10)kHz.

  17. Some properties of atomic beam produced by laser induced ablation of Li target

    International Nuclear Information System (INIS)

    Pulsed atomic beams produced in vacuum by laser induced ablation from a lithium target are analyzed by laser induced fluorescence (LIF). The 1-mixing processes induced in the n = 9, 10 Li Rydberg states by collisions with CO2 molecules illustrate the application of the method. Resolution is limited by the 1 mm diameter of the probe laser beam. Combining LIF and absorption measurements gives nLi as a function of time at various distances from the target surface. The investigation of the Li-C02 1-mixing process in a heat pipe oven proved impossible due to the high reactivity of Li with C02. This problem was solved by renewing the Li atoms at each laser shot. Values obtained for n = 9, n = 10 are k = 17 x 10-8 and 15 x 10-8 cc/sec, respectively

  18. Crossed beam reactive scattering of oxygen atoms and surface scattering studies of gaseous condensation

    Energy Technology Data Exchange (ETDEWEB)

    Sibener, S.J.

    1979-09-01

    A high pressure, radio frequency discharge nozzle beam source was developed for the production of very intense (greater than or equal to 10/sup 18/ atoms sr/sup -1/ sec/sup -1/) supersonic beams of oxygen atoms. This source is capable of producing seeded beams of ground state O(/sup 3/P/sub J/) atoms when dilute oxygen-argon mixtures are used, with molecular dissociation levels exceeding 80% being realized for operation at pressures up to 350 torr. When dilute oxygen-helium mixtures are employed both ground state O(/sup 3/P/sub J/) and excited state O(/sup 1/D/sub 2/) atoms are present in the terminal beam, with molecular dissociation levels typically exceeding 60% being achieved for operation at pressures up to 200 torr. Atomic oxygen mean translational energies from 0.14 to 0.50 eV were obtained using the seeded beams technique, with Mach numbers as high as 10 (FWHM ..delta.. v/v approx. = 20%) being realized. The IC1, CF/sub 3/I, C/sub 6/H/sub 6/, and C/sub 6/D/sub 6/ reactions are discussed in detail. The IC1 and CF/sub 3/I studies have enabled us to determine an improved value for the bond energy of the IO radical: D/sub o/(IO) = 55 +- 2 kcal/mole. The IO product angular and velocity distributions have been used to generate center-of-mass flux contour maps, which indicate that these two reactions proceed via relatively long-lived collision complexes whose mean lifetimes are slightly shorter than their respective rotational periods. The O(/sup 3/P/sub J/) + C/sub 6/H/sub 6/ and C/sub 6/D/sub 6/ reactions were studied in order to elucidate the reaction mechanism, and, in particular, to identify the primary reaction products produced in these reactions. Finally, a series of beam-surface scattering experiments are described which examined the internal and translational energy dependence of molecular condensation probabilities for collisions involving either CC1/sub 4/ or SF/sub 6/ and their respective condensed phases. 117 references. (JFP)

  19. Crossed beam reactive scattering of oxygen atoms and surface scattering studies of gaseous condensation

    International Nuclear Information System (INIS)

    A high pressure, radio frequency discharge nozzle beam source was developed for the production of very intense (greater than or equal to 1018 atoms sr-1 sec-1) supersonic beams of oxygen atoms. This source is capable of producing seeded beams of ground state O(3P/sub J/) atoms when dilute oxygen-argon mixtures are used, with molecular dissociation levels exceeding 80% being realized for operation at pressures up to 350 torr. When dilute oxygen-helium mixtures are employed both ground state O(3P/sub J/) and excited state O(1D2) atoms are present in the terminal beam, with molecular dissociation levels typically exceeding 60% being achieved for operation at pressures up to 200 torr. Atomic oxygen mean translational energies from 0.14 to 0.50 eV were obtained using the seeded beams technique, with Mach numbers as high as 10 (FWHM Δ v/v approx. = 20%) being realized. The IC1, CF3I, C6H6, and C6D6 reactions are discussed in detail. The IC1 and CF3I studies have enabled us to determine an improved value for the bond energy of the IO radical: D/sub o/(IO) = 55 +- 2 kcal/mole. The IO product angular and velocity distributions have been used to generate center-of-mass flux contour maps, which indicate that these two reactions proceed via relatively long-lived collision complexes whose mean lifetimes are slightly shorter than their respective rotational periods. The O(3P/sub J/) + C6H6 and C6D6 reactions were studied in order to elucidate the reaction mechanism, and, in particular, to identify the primary reaction products produced in these reactions. Finally, a series of beam-surface scattering experiments are described which examined the internal and translational energy dependence of molecular condensation probabilities for collisions involving either CC14 or SF6 and their respective condensed phases. 117 references

  20. Characterization of the Plasma Edge for Technique of Atomic Helium Beam in the CIEMAT Fusion Device

    International Nuclear Information System (INIS)

    In this report, the measurement of Electron Temperature and Density in the Boundary Plasma of TJ-II with a Supersonic Helium Beam Diagnostic and work devoted to the upgrading of this technique are described. Also, simulations of Laser Induced Fluorescence (LIF) studies of level populations of electronically excited He atoms are shown. This last technique is now being installed in the CIEMAT fusion device. (Author )

  1. Two experiments with cold atoms: I. Application of Bessel beams for atom optics, and II. Spectroscopic measurements of Rydberg blockade effect

    Science.gov (United States)

    Arakelyan, Ilya

    In this dissertation we report the results of two experimental projects with laser-cooled rubidium atoms: I. Application of Bessel beams for atom optics, and II. Spectroscopic measurements of Rydberg blockade effect. The first part of the thesis is devoted to the development of new elements of atom optics based on blue-detuned high-order Bessel beams. Properties of a 4thorder Bessel beam as an atomic guide were investigated for various parameters of the hollow beam, such as the detuning from an atomic resonance, size and the order of the Bessel beam. We extended its application to create more complicated interferometer-type structures by demonstrating a tunnel lock, a novel device that can split an atomic cloud, transport it, delay, and switch its propagation direction between two guides. We reported a first-time demonstration of an atomic beam switch based on the combination of two crossed Bessel beams. We achieved the 30% efficiency of the switch limited by the geometrical overlap between the cloud and the intersection volume of the two tunnels, and investigate the heating processes induced by the switch. We also showed other applications of crossed Bessel beams, such as a 3-D optical trap for atoms confined in the intersection volume of two hollow beams and a splitter of the atomic density. The second part of this dissertation is devoted to the spectroscopic measurements of the Rydberg blockade effect, a conditional suppression of Rydberg excitations depending on the state of a control atom. We assembled a narrow-linewidth, tunable, frequency stabilized laser system at 480 nm to excite laser-cooled rubidium atoms to Rydberg states with a high principal quantum number n ˜ 50 through a two-photon transition. We applied the laser system to observe the Autler-Townes splitting of the intermediate 5p3/2 state and used the broadening of the resonance features to investigate the enhancement of Rydberg-Rydberg interactions in the presence of an external electric field.

  2. Radiative lifetimes in MoI using a novel atomic beam source

    International Nuclear Information System (INIS)

    Radiative lifetimes of the 4d5(a6S)5pz7P0 levels and the 4d5(a6S)5pz5P0 levels in MoI are reported as follows: tau(z7P04) = 15.9 ns, tau(z7P03) = 17.0 ns, tau(z7P02) = 17.1 ns, tau(z5P03) = 22.3 ns, tau(z5P02) = 22.1 ns, and tau(z5P01) = 21.7 ns (+-5%). The lifetimes are measured using time resolved laser induced fluorescence and a novel atomic beam source. This novel hollow cathode effusive beam source produces an intense beam of ground state Mo atoms and metastable Mo atoms. Our measurements on the z7P0 levels are in agreement with earlier lifetime measurements. Our measurements on the z5P0 levels are the first direct radiative lifetime measurements of these levels; the z5P0 measurements are of particular interest because the a5S → z5P0 multiplet is used to determine the solar abundance of Mo. (orig.)

  3. Polarized Atomic Hydrogen Beam Tests in the Michigan Ultra-Cold Jet Target

    Science.gov (United States)

    Kageya, T.; Blinov, B. B.; Denbow, J. M.; Kandes, M. C.; Krisch, A. D.; Kulkarni, D. A.; Lehman, M. A.; Luppov, V. G.; Morozov, V. S.; Murray, J. R.; Peters, C. C.; Raymond, R. S.; Ross, M. R.; Yonehara, K.; Borisov, N. S.; Fimushkin, V. V.; Kleppner, D.; Grishin, V. N.; Mysnik, A. L.

    2001-04-01

    To study spin effects in high energy collisions, we are developing an ultra-cold high-density jet target of proton-spin-polarized hydrogen atoms (Michigan Jet Target). The target uses a 12 Tesla magnetic field and a 0.3 K separation cell coated with superfluid helium-4 to produce a slow monochromatic electron-spin-polarized atomic hydrogen beam; an rf transition unit then converts this into a proton-spin-polarized beam, which is focused by a superconducting sextupole into the interaction region. The Jet produced, at the detector, a spin-polarized atomic hydrogen beam with a measured intensity of about 1.7 10^15 H s-1 and a FWHM area of less than 0.13 cm^2. This intensity corresponds to a free jet density of about 1.3 10^12 H cm-3 with a proton polarization of about 50%. When the transition RF unit is installed, we expect a proton polarization higher than 90%.

  4. 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.

  5. Atomic Funnel Composed of an HE11-Mode Output Hollow Beam

    Institute of Scientific and Technical Information of China (English)

    倪赟; 刘南春; 印建平

    2003-01-01

    Using exact solutions of Maxwell equations based on the vector model, we calculate the diffracted near- and far-field distributions of the HEi1-mode output beam from a micron-sized hollow optical fibre under the Fresnel approximation, and compare the differences between the HE11- and LP01-mode output beams. Our study shows that it is unsuitable to calculate the diffracted near-field distribution of the hollow fibre by using weakly waveguiding approximation, and the near- and far-field intensity distributions of the HE11-mode output beam are doughnut-like, which can be used to form a simple atomic funnel as it is blue-detuned.

  6. 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. PMID:26628128

  7. Intense electron beams from GaAs photocathodes as a tool for molecular and atomic physics

    Energy Technology Data Exchange (ETDEWEB)

    Krantz, Claude

    2009-10-28

    We present cesium-coated GaAs photocathodes as reliable sources of intense, quasi-monoenergetic electron beams in atomic and molecular physics experiments. In long-time operation of the Electron Target of the ion storage ring TSR in Heidelberg, cold electron beams could be realised at steadily improving intensity and reliability. Minimisation of processes degrading the quantum efficiency allowed to increase the extractable current to more than 1mA at usable cathode lifetimes of 24 h or more. The benefits of the cold electron beam with respect to its application to electron cooling and electron-ion recombination experiments are discussed. Benchmark experiments demonstrate the superior cooling force and energy resolution of the photoelectron beam compared to its thermionic counterparts. The long period of operation allowed to study the long-time behaviour of the GaAs samples during multiple usage cycles at the Electron Target and repeated in-vacuum surface cleaning by atomic hydrogen exposure. An electron emission spectroscopy setup has been implemented at the photocathode preparation chamber of the Electron Target. Among others, this new facility opened the way to a novel application of GaAs (Cs) photocathodes as robust, ultraviolet-driven electron emitters. Based on this principle, a prototype of an electron gun, designed for implementation at the HITRAP setup at GSI, has been built and taken into operation successfully. (orig.)

  8. OPTIMIZATION AND CHARACTERIZATION OF ELECTRON BEAM RESIST USING ATOMIC FORCE MICROSCOPY

    Directory of Open Access Journals (Sweden)

    - Sutikno

    2012-01-01

    Full Text Available Resis negatif ma-N 2403 dan 495 K PMMA memiliki resolusi yang baik untuk aplikasi litografi berkas elektron (EBL. Ketebalanresist optimal memainkan peran penting dalam paparan berkas elektron. Oleh karena itu, dalam penelitian ini, ketebalan darikedua resist yang dioptimalkan menggunakan spincoater dalam jangkauan laju spin 1000-6000 rpm. Semakin laju spin meningkat,ketebalan resist menurun juga. Morfologi permukaan resist dikarakterisasi dengan mikroskop gaya atom. Butir butir resist nampakpanjang. Dalam analisis AFM, permukaan profil resist negatif ma-N 2403 dan 495 K PMMA nampak seperti kerucut. Negative resist ma-N 2403 and 495 K PMMA have good resolution for electron beam lithography (EBL application. The optimumresist thickness plays significant role in e-beam exposure. Therefore, in this research, thicknesses of both resists were optimizedusing spincoater within spin speeds of 1000-6000 rpm. As spin speed increased, resist thickness decreased as well. Morphology ofresist surfaces were characterized using atomic force microscopy (AFM. Grains of resist show long grains. In AFM analyses,surface profiles of negative resist ma-N 2403 and 495 K PMMA show cone peaks.Keywords: e-beam resist; spincoater; e-beam lithography

  9. Intense electron beams from GaAs photocathodes as a tool for molecular and atomic physics

    International Nuclear Information System (INIS)

    We present cesium-coated GaAs photocathodes as reliable sources of intense, quasi-monoenergetic electron beams in atomic and molecular physics experiments. In long-time operation of the Electron Target of the ion storage ring TSR in Heidelberg, cold electron beams could be realised at steadily improving intensity and reliability. Minimisation of processes degrading the quantum efficiency allowed to increase the extractable current to more than 1mA at usable cathode lifetimes of 24 h or more. The benefits of the cold electron beam with respect to its application to electron cooling and electron-ion recombination experiments are discussed. Benchmark experiments demonstrate the superior cooling force and energy resolution of the photoelectron beam compared to its thermionic counterparts. The long period of operation allowed to study the long-time behaviour of the GaAs samples during multiple usage cycles at the Electron Target and repeated in-vacuum surface cleaning by atomic hydrogen exposure. An electron emission spectroscopy setup has been implemented at the photocathode preparation chamber of the Electron Target. Among others, this new facility opened the way to a novel application of GaAs (Cs) photocathodes as robust, ultraviolet-driven electron emitters. Based on this principle, a prototype of an electron gun, designed for implementation at the HITRAP setup at GSI, has been built and taken into operation successfully. (orig.)

  10. High energy-intensity atomic oxygen beam source for low earth orbit materials degradation studies

    International Nuclear Information System (INIS)

    A high intensity (1019O-atoms/s-sr) high energy (5 eV) source of oxygen atoms has been developed that produces a total fluence of 1022 O-atoms/cm2 in less than 100 hours of continuous operation at a distance of 15 cm from the source. The source employs a CW CO2 laser sustained discharge to form a high temperature (15,000 K) plasma in the throat of a 0.3-mm diameter nozzle using 3--8 atmospheres of rare gas/O2 mixtures. Visible and infrared photon flux levels of 1 watt/cm2 have been measured 15 cm downstream of the source while vacuum UV (VUV) fluxes are comparable to that measured in low earth orbit. The reactions of atomic oxygen with kapton, Teflon, silver, and various coatings have been studied. The oxidation of kapton (reaction efficiency = 3 /times/ 10/sup /minus/24/ cm /+-/ 50%) has an activation energy of 0.8 Kcal/mole over the temperature range of 25/degree/C to 100/degree/C at a beam energy of 1.5 eV and produces low molecular weight gas phase reaction products (H2O, NO, CO2). Teflon reacts with ∼0.1--0.2 efficiency to that of kapton at 25/degree/C and both surfaces show a rug-like texture after exposure to the O-atom beam. Angular scattering distribution measurements of O-atoms show a near cosine distribution from reactive surfaces indicating complete accommodation of the translational energy with the surface while a nonreactive surface (nickel oxide) shows specular-like scattering with 50% accommodation of the translational energy with the surface. A technique for simple on orbit chemical experiments using resistance measurements of coated silver strips is described. 9 figs

  11. Twin-atom beam generation in a one-dimensional Bose gas

    International Nuclear Information System (INIS)

    One of the most fascinating aspects of quantum physics is particle-wave duality, leading to striking analogies in the behavior of light and matter. Wave-like phenomena of matter on a macroscopic scale are especially pronounced in quantum-degenerate atomic gases. In these, strongly populated matter-wave modes give rise to coherence properties resembling those of laser light, enabling interferometry and homodyne measurements with Bose-Einstein condensates. In recent years, numerous experiments and theory proposals have been developed to extend this analogy into the realm of quantum optics, highlighting the complex interplay of wave and particle aspects of a degenerate atom gas. In quantum optics, a powerful theory framework is readily avail- able, and numerous ground-breaking experiments with non-classical light have been performed. The realization of similar experiments using matter waves holds promise for both fundamental tests of quantum mechanics, and future metrology applications. This approach is promoted by the intrinsic atom-atom interactions in a condensate, that allow to efficiently access non-classical quantum states, without the need for non-linear media as in light optics. In this thesis, a scheme to generate twin-atom beams, confined to a one-dimensional wave-guide geometry on an atom chip, was realized. The twin beams emerge from a degenerate one-dimensional Bose gas, propagate as wave packets with opposite momenta, and show quantum correlations that ideally lead to complete suppression of relative population fluctuations (number squeezing). This process, which operates in a strongly Bose-enhanced regime, is in close analogy to twin-photon beam generation in an optical parametric oscillator, a key tool in both fundamental and applied photonics. In our experiment, using time-of-flight fluorescence imaging, almost perfect number squeezing between the twin beams is observed, for the first time in the regime of high mode population. Furthermore, the

  12. Spectroscopy and Stark-effect of Rydberg states in Ca and Sr in an atomic beam experiment

    International Nuclear Information System (INIS)

    Rydberg states of Calcium and Strontium were excited by laser radiation in an atomic beam experiment. Such spectroscopy of the Rydberg series could be done in both elements and also the Stark effect was examined in Strontium. (BEF)

  13. Nuclear structure of light thallium isotopes as deduced from laser spectroscopy on a fast atom beam

    International Nuclear Information System (INIS)

    After optimizing the system by experiments on /sup 201,203,205/Tl, the neutron-deficient isotopes 189-193Tl have been studied using the collinear fast atom beam laser spectroscopy system at UNISOR on-line to the Holifield Heavy Ion Research Facility. A sensitive system for the measurements was developed since the light isotopes were available in mass-separated beams of only 7 x 104 to 4 x 105 atoms per second. By laser excitation of the 535 nm atomic transitions of atoms in the beam, the 6s27s 2S/sub 1/2/ and 6s26s 2P/sub 3/2/ hyperfine structures were measured, as were the isotope shifts of the 535 nm transitions. From these, the magnetic dipole moments, spectroscopic quadrupole moments and isotopic changes in mean-square charge radius were deduced. The magnetic dipole moments are consistent with previous data. The /sup 190,192/Tl isotopes show a considerable difference in quadrupole deformations as well as an anomalous isotope shift with respect to 194Tl. A large isomer shift in 193Tl is observed implying a larger deformation in the 9/2- isomer than in the 1/2+ ground state. The /sup 189,191,193/Tl isomers show increasing deformation away from stability. A deformed shell model calculation indicates that this increase in deformation can account for the dropping of the 9/2- band in these isotopes while an increase in neutron pairing correlations, having opposite and compensating effects on the rotational moment of inertia, maintains the 9/2- strong-coupled band structure. 105 refs., 27 figs

  14. Diffracted field distribution from a knife-edge truncated semi- Gaussian beam as an atomic (molecular) mirror

    Institute of Scientific and Technical Information of China (English)

    Zheng Ping; Gao Wei-Jian; Yin Jian-Ping

    2006-01-01

    We investigate the diffraction characteristics of an incident Gaussian beam cut by a straight edge bounding a semi-infinite opaque plane using Kirchhoff scalar wave theory in the Fresnel limit, and propose a new and simple mirror scheme to reflect atoms by using the intensity gradient induced by a blue-detuned semi-Gaussian laser beam. The optical potential of the diffracted light of the knife-cut semi-Gaussian beam for 85Rb atom and its spontaneous emission probability are calculated and compared with the performance of the evanescent-wave mirror. Our study shows that the optical potential of the diffracted light of the semi-Gaussian beam is far higher than that of the evanescent light wave, and the maximum normal velocity of the incident atoms can be far greater than that of the evanescent light wave under the same parameters, so the blue-detuned semi-Gaussian beam, as a novel atomic mirror, can be used to efficiently reflect cold atoms with a normal velocity of greater than 1 m/s. However, the intensity gradient (force) of the diffracted light of the semi-Gaussian-beam is much smaller than that of the evanescent light wave, so its spontaneous emission probability is greater than that from the evanescent-wave when the normal velocity of incident atoms is greater.

  15. Optimized coupling of cold atoms into a fiber using a blue-detuned hollow-beam funnel

    International Nuclear Information System (INIS)

    We theoretically investigate the process of coupling cold atoms into the core of a hollow-core photonic-crystal optical fiber using a blue-detuned Laguerre-Gaussian beam. In contrast to the use of a red-detuned Gaussian beam to couple the atoms, the blue-detuned hollow beam can confine cold atoms to the darkest regions of the beam, thereby minimizing shifts in the internal states and making the guide highly robust to heating effects. This single optical beam is used as both a funnel and a guide to maximize the number of atoms into the fiber. In the proposed experiment, Rb atoms are loaded into a magneto-optical trap (MOT) above a vertically oriented optical fiber. We observe a gravito-optical trapping effect for atoms with high orbital momentum around the trap axis, which prevents atoms from coupling to the fiber: these atoms lack the kinetic energy to escape the potential and are thus trapped in the laser funnel indefinitely. We find that by reducing the dipolar force to the point at which the trapping effect just vanishes, it is possible to optimize the coupling of atoms into the fiber. Our simulations predict that by using a low-power (2.5 mW) and far-detuned (300 GHz) Laguerre-Gaussian beam with a 20-μm-radius core hollow fiber, it is possible to couple 11% of the atoms from a MOT 9 mm away from the fiber. When the MOT is positioned farther away, coupling efficiencies over 50% can be achieved with larger core fibers.

  16. Preparation of state purified beams of He, Ne, C, N, and O atoms

    Science.gov (United States)

    Jankunas, Justin; Reisyan, Kevin S.; Osterwalder, Andreas

    2015-03-01

    The production and guiding of ground state and metastable C, N, and O atoms in a two-meter-long, bent magnetic guide are described. Pure beams of metastable He(3S1) and Ne(3P2), and of ground state N(4S3/2) and O(3P2) are obtained using an Even-Lavie valve paired with a dielectric barrier discharge or electron bombardment source. Under these conditions no electronically excited C, N, or O atoms are observed at the exit of the guide. A general valve with electron impact excitation creates, in addition to ground state atoms, electronically excited C(3P2; 1D2) and N(2D5/2; 2P3/2) species. The two experimental conditions are complimentary, demonstrating the usefulness of a magnetic guide in crossed or merged beam experiments such as those described in Henson et al. [Science 338, 234 (2012)] and Jankunas et al. [J. Chem. Phys. 140, 244302 (2014)].

  17. Preparation of state purified beams of He, Ne, C, N, and O atoms

    Energy Technology Data Exchange (ETDEWEB)

    Jankunas, Justin; Reisyan, Kevin S.; Osterwalder, Andreas, E-mail: andreas.osterwalder@epfl.ch [Institute for Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland)

    2015-03-14

    The production and guiding of ground state and metastable C, N, and O atoms in a two-meter-long, bent magnetic guide are described. Pure beams of metastable He({sup 3}S{sub 1}) and Ne({sup 3}P{sub 2}), and of ground state N({sup 4}S{sub 3/2}) and O({sup 3}P{sub 2}) are obtained using an Even-Lavie valve paired with a dielectric barrier discharge or electron bombardment source. Under these conditions no electronically excited C, N, or O atoms are observed at the exit of the guide. A general valve with electron impact excitation creates, in addition to ground state atoms, electronically excited C({sup 3}P{sub 2}; {sup 1}D{sub 2}) and N({sup 2}D{sub 5/2}; {sup 2}P{sub 3/2}) species. The two experimental conditions are complimentary, demonstrating the usefulness of a magnetic guide in crossed or merged beam experiments such as those described in Henson et al. [Science 338, 234 (2012)] and Jankunas et al. [J. Chem. Phys. 140, 244302 (2014)].

  18. Theory of longitudinal atomic beam spin echo and parity violating Berry-phases in atoms; Theorie des longitudinalen Atomstrahl-Spinechos und paritaetsverletzende Berry-Phasen in Atomen

    Energy Technology Data Exchange (ETDEWEB)

    Bergmann, T.F.

    2006-07-19

    We present a nonrelativistic theory for the quantum mechanical description of longitudinal atomic beam spin echo experiments, where a beam of neutral atoms is subjected to static electric and magnetic fields. The atomic wave function is the solution of a matrix-valued Schroedinger equation and can be written as superposition of local (atomic) eigenstates of the potential matrix. The position- and time-dependent amplitude function of each eigenstate represents an atomic wave packet and can be calculated in a series expansion with a master formula that we derive. The zeroth order of this series expansion describes the adiabatic limit, whereas the higher order contributions contain the mixing of the eigenstates and the corresponding amplitude functions. We give a tutorial for the theoretical description of longitudinal atomic beam spin echo experiments and for the so-called Fahrplan model, which is a visualisation tool for the propagation of wave packets of different atomic eigenstates. As an example for the application of our theory, we study parity violating geometric (Berry-)phases. In this context, we define geometric flux densities, which for certain field configurations can be used to illustrate geometric phases in a vector diagram. Considering an example with a specific field configuration, we prove the existence of a parity violating geometric phase. (orig.)

  19. Spatial solitons in a three-level atomic medium supported by a Laguerre-Gaussian control beam

    International Nuclear Information System (INIS)

    We investigate the existence and stability of various types of spatial solitons in a three-level atomic medium with Laguerre-Gaussian control beam. Radial and azimuthal modulations of the medium properties, introduced by the control beam, provide possibilities for existence of diverse soliton patterns and dynamics. Beam diffraction provides additional soliton controllability. All types of solitons can be generated at very low input energy at a few-photon level.

  20. Atomic layer deposition of HfO2 on graphene through controlled ion beam treatment

    Science.gov (United States)

    Kim, Ki Seok; Oh, Il-Kwon; Jung, Hanearl; Kim, Hyungjun; Yeom, Geun Young; Kim, Kyong Nam

    2016-05-01

    The polymer residue generated during the graphene transfer process to the substrate tends to cause problems (e.g., a decrease in electron mobility, unwanted doping, and non-uniform deposition of the dielectric material). In this study, by using a controllable low-energy Ar+ ion beam, we cleaned the polymer residue without damaging the graphene network. HfO2 grown by atomic layer deposition on graphene cleaned using an Ar+ ion beam showed a dense uniform structure, whereas that grown on the transferred graphene (before Ar+ ion cleaning) showed a non-uniform structure. A graphene-HfO2-metal capacitor fabricated by growing 20-nm thick HfO2 on graphene exhibited a very low leakage current (graphene, whereas a similar capacitor grown using the transferred graphene showed high leakage current.

  1. Bright focused ion beam sources based on laser-cooled atoms

    CERN Document Server

    McClelland, J J; Knuffman, B; Twedt, K A; Schwarzkopf, A; Wilson, T M

    2015-01-01

    Nanoscale focused ion beams (FIBs) represent one of the most useful tools in nanotechnology, enabling nanofabrication via milling and gas-assisted deposition, microscopy and microanalysis, and selective, spatially resolved doping of materials. Recently, a new type of FIB source has emerged, which uses ionization of laser cooled neutral atoms to produce the ion beam. The extremely cold temperatures attainable with laser cooling (in the range of 100 uK or below) result in a beam of ions with a very small transverse velocity distribution. This corresponds to a source with extremely high brightness that rivals or may even exceed the brightness of the industry standard Ga+ liquid metal ion source. In this review we discuss the context of ion beam technology in which these new ion sources can play a role, their principles of operation, and some examples of recent demonstrations. The field is relatively new, so only a few applications have been demonstrated, most notably low energy ion microscopy with Li ions. Never...

  2. Bright focused ion beam sources based on laser-cooled atoms

    Science.gov (United States)

    McClelland, J. J.; Steele, A. V.; Knuffman, B.; Twedt, K. A.; Schwarzkopf, A.; Wilson, T. M.

    2016-03-01

    Nanoscale focused ion beams (FIBs) represent one of the most useful tools in nanotechnology, enabling nanofabrication via milling and gas-assisted deposition, microscopy and microanalysis, and selective, spatially resolved doping of materials. Recently, a new type of FIB source has emerged, which uses ionization of laser cooled neutral atoms to produce the ion beam. The extremely cold temperatures attainable with laser cooling (in the range of 100 μK or below) result in a beam of ions with a very small transverse velocity distribution. This corresponds to a source with extremely high brightness that rivals or may even exceed the brightness of the industry standard Ga+ liquid metal ion source. In this review, we discuss the context of ion beam technology in which these new ion sources can play a role, their principles of operation, and some examples of recent demonstrations. The field is relatively new, so only a few applications have been demonstrated, most notably low energy ion microscopy with Li ions. Nevertheless, a number of promising new approaches have been proposed and/or demonstrated, suggesting that a rapid evolution of this type of source is likely in the near future.

  3. Controllable Asymmetric Matter-wave Beam Splitter and Ring Potential on an Atom Chip

    CERN Document Server

    Kim, S J; Gang, S T; Anderson, D; Kim, J B

    2015-01-01

    We have constructed an asymmetric matter-wave beam splitter and a ring potential on an atom chip with Bose-Einstein condensates using radio-frequency dressing. By applying rf-field parallel to the quantization axis in the vicinity of the static trap minima added to perpendicular rf-fields, versatile controllability on the potentials is realized. Asymmetry of the rf-induced double well is manipulated without discernible displacement of the each well along horizontal and vertical direction. Formation of an isotropic ring potential on an atom chip is achieved by compensating the gradient due to gravity and inhomogeneous coupling strength. In addition, position and rotation velocity of a BEC along the ring geometry are controlled by the relative phase and the frequency difference between the rf-fields, respectively.

  4. Influence of laser power on deposition of the chromium atomic beam in laser standing wave

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    One-dimensional deposition of collimated Cr atomic beam focused by a near-resonant Gaussian standing-laser field with wavelength of 425.55 nm is examined from particle-optics approach by using an adaptive step size,fourth-order Runge-Kutta type algorithm.The influence of laser power on deposition of atoms in laser standing wave is discussed and the simulative result shows that the FWHM of nanometer stripe is 102 nm and contrast is 2:1 with laser power equal to 3 mW,the FWHM is 1.2 nm and contrast is 32:1 with laser power equal to 16 mW,but with laser power increase,equal to 50 mW,the nonmeter structure forms the multi-crests and exacerbates.

  5. A study of the spectrum of natural dysprosium with the laser-atomic-beam technique

    International Nuclear Information System (INIS)

    A high resolution study of 31 transitions in dysprosium in the wavelength regions 435-470 nm and 560-670 nm has been performed using CW dye lasers and a collimated atomic beam. Transitions from the 5I8 ground state as well as from the metastable states at 4134 cm-15I7 of the 4f106s25I multiplet were studied. In this paper the results of isotope shift measurements on transitions to the excited-state configurations 4f106s6p, 4f96s25d, 4f96s5d2 are presented and values for the specific mass shift and atomic factor of the field shift for the various configurations are evaluated. (author)

  6. High momentum splitting of matter-waves by an atom chip field gradient beam-splitter

    CERN Document Server

    Machluf, Shimon; Folman, Ron

    2012-01-01

    The splitting of matter-waves into superposition states is a fundamental tool for studying the basic tenets of quantum behavior, as well as a building block for numerous technological applications. We report on the first realization of a beam-splitter by a combination of magnetic field gradients and a radio-frequency technique. It may be used for freely propagating or trapped atoms in a Bose-Einstein condensate or a thermal state. It has the advantageous feature of endowing its superposition state with a large differential momentum in the direction parallel or transverse to the atoms' motion, thereby, for example enabling to open large angles. As large space-time area of an interferometer increases its sensitivity, this may be used for new kinds of interferometry experiments (e.g. large angle Sagnac interferometry). Furthermore, it is also simple to use, fast, and does not require light.

  7. Precision measurement of transverse velocity distribution of a strontium atomic beam

    Directory of Open Access Journals (Sweden)

    F. Gao

    2014-02-01

    Full Text Available We measure the transverse velocity distribution in a thermal Sr atomic beam precisely by velocity-selective saturated fluorescence spectroscopy. The use of an ultrastable laser system and the narrow intercombination transition line of Sr atoms mean that the resolution of the measured velocity can reach 0.13 m/s, corresponding to 90 μK in energy units. The experimental results are in very good agreement with the results of theoretical calculations. Based on the spectroscopic techniques used here, the absolute frequency of the intercombination transition of 88Sr is measured using an optical-frequency comb generator referenced to the SI second through an H maser, and is given as 434 829 121 318(10 kHz.

  8. Precision measurement of transverse velocity distribution of a strontium atomic beam

    Energy Technology Data Exchange (ETDEWEB)

    Gao, F.; Liu, H.; Tian, X. [CAS Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Xi' an 710600 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xu, P.; Wang, Y.; Ren, J. [CAS Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Xi' an 710600 (China); Wu, Haibin, E-mail: hbwu@phy.ecnu.edu.cn [State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062 (China); Chang, Hong, E-mail: changhong@ntsc.ac.cn [CAS Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Xi' an 710600 (China); State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062 (China)

    2014-02-15

    We measure the transverse velocity distribution in a thermal Sr atomic beam precisely by velocity-selective saturated fluorescence spectroscopy. The use of an ultrastable laser system and the narrow intercombination transition line of Sr atoms mean that the resolution of the measured velocity can reach 0.13 m/s, corresponding to 90 μK in energy units. The experimental results are in very good agreement with the results of theoretical calculations. Based on the spectroscopic techniques used here, the absolute frequency of the intercombination transition of {sup 88}Sr is measured using an optical-frequency comb generator referenced to the SI second through an H maser, and is given as 434 829 121 318(10) kHz.

  9. Noise Effects on Entangled Coherent State Generated via Atom-Field Interaction and Beam Splitter

    Science.gov (United States)

    Najarbashi, G.; Mirzaei, S.

    2016-05-01

    In this paper, we introduce a controllable method for producing two and three-mode entangled coherent states (ECS's) using atom-field interaction in cavity QED and beam splitter. The generated states play central roles in linear optics, quantum computation and teleportation. We especially focus on qubit, qutrit and qufit like ECS's and investigate their entanglement by concurrence measure. Moreover, we illustrate decoherence properties of ECS's due to noisy channels, using negativity measure. At the end the effect of noise on monogamy inequality is discussed.

  10. Use of an Atmospheric Atomic Oxygen Beam for Restoration of Defaced Paintings

    Science.gov (United States)

    Banks, Bruce A.; Rutledge, Sharon K.; Karla, Margaret; Norris, Mary Jo; Real, William A.; Haytas, Christy A.

    1999-01-01

    An atmospheric atomic oxygen beam has been found to be effective in removing organic materials through oxidation that are typical of graffiti or other contaminant defacements which may occur to the surfaces of paintings. The technique, developed by the National Aeronautics and Space Administration, is portable and was successfully used at the Carnegie Museum of Art to remove a lipstick smudge from the surface of porous paint on the Andy Warhol painting "Bathtub." This process was also evaluated for suitability to remove felt tip and ball point ink graffiti from paper, gesso on canvas and cotton canvas.

  11. Absorption spectroscopy characterization measurements of a laser-produced Na atomic beam

    Energy Technology Data Exchange (ETDEWEB)

    Ching, C.H.; Bailey, J.E.; Lake, P.W.; Filuk, A.B.; Adams, R.G.; McKenney, J.

    1996-06-01

    This work describes a pulsed Na atomic beam source developed for spectroscopic diagnosis of a high-power ion diode on the Particle Beam Fusion Accelerator II. The goal is to produce a {approximately} 10{sup 12}-cm{sup {minus}3}-density Na atomic beam that can be injected into the diode acceleration gap to measure electric and magnetic fields from the Stark and Zeeman effects through laser-induced-fluorescence or absorption spectroscopy. A {approximately} 10 ns fwhm, 1.06 {micro}m, 0.6 J/cm{sup 2} laser incident through a glass slide heats a Na-bearing thin film, creating a plasma that generates a sodium vapor plume. A {approximately} 1 {micro}sec fwhm dye laser beam tuned to 5,890 {angstrom} is used for absorption measurement of the Na I resonant doublet by viewing parallel to the film surface. The dye laser light is coupled through a fiber to a spectrograph with a time-integrated CCD camera. A two-dimensional mapping of the Na vapor density is obtained through absorption measurements at different spatial locations. Time-of-flight and Doppler broadening of the absorption with {approximately} 0.1 {angstrom} spectral resolution indicate that the Na neutral vapor temperature is about 0.5 to 2 eV. Laser-induced-fluorescence from {approximately} 1 {times} 10{sup 12}-cm{sup {minus}3} Na I 3s-3p lines observed with a streaked spectrograph provides a signal level sufficient for {approximately} 0.06 {angstrom} wavelength shift measurements in a mock-up of an ion diode experiment.

  12. Generation of energetic He atom beams by a pulsed positive corona discharge

    International Nuclear Information System (INIS)

    Time-of-flight measurements were made of neutral helium atom beams extracted from a repetitive, pulsed, positive-point corona discharge. Two strong neutral peaks, one fast and one slow, were observed, accompanied by a prompt photon peak and a fast ion peak. All peaks were correlated with the pulsing of the discharge. The two types of atoms appear to be formed by different mechanisms at different stages of the corona discharge. The fast atoms had energies of 190 eV and were formed at the onset of the pulsing, approximately 0.7 μs before the maximum of the photon peak. The slow peak, composed of electronically metastable He atoms, originated 30 50 μs after the photon pulse, and possessed a nearly thermal velocity distribution. The velocity distribution was typical of an undisturbed supersonic expansion with a stagnation temperature of 131 K and a speed ratio of 3.6. Peak intensities and velocities were measured as a function of source voltage, stagnation pressure, and skimmer voltage. copyright 1997 American Institute of Physics

  13. Influence of the Ion-to-Atom Ratio on the Structure of CeO2 Buffer Layer by Ion Beam Assisted E-Beam Evaporation

    Science.gov (United States)

    Kim, Chang Su; Jo, Sung Jin; Kim, Woo Jin; Koo, Won Hoe; Baik, Hong Koo; Lee, Se Jong

    2005-09-01

    Using ion-beam assisted e-beam evaporation with the ion beam directed at 55° to the normal of the film plane, (200) oriented CeO2 films with biaxial texture were deposited on Hastelloy C276 substrates at room temperature. The crystalline quality and in-plane orientation of films was investigated by X-ray diffraction 2θ-scan and Φ-scan, atomic force microscopy (AFM). It was shown that the in-plane and out-of-plane textures of the CeO2 films were controlled by the deposition parameters. The orientation of the films was studied as a function of ion-to-atom ratio and film thickness. The ion-to-atom ratio was varied by independently adjusting the deposition rate and the ion current density. Under optimum condition, (200) textured CeO2 films have been successfully grown on Hastelloy C276.

  14. High resolution electron imaging system for sub-micron sized metastable atom beams produced by Stern Gerlach interferometry

    Science.gov (United States)

    Milosavljevic, A. R.; Bocvarski, V.; Jureta, J.; Marinkovic, B. P.; Karam, J.-C.; Grucker, J.; Perales, F.; Vassilev, G.; Reinhardt, J.; Robert, J.; Baudon, J.

    2005-10-01

    The method of modulating an atom beam profile by an immaterial magnetic mask generated in a Stern-Gerlach interferometer is recalled. A special magnetic configuration aimed at producing a single central bright interference fringe (atomic spot) was used. The effects of velocity spread, source coherence and source size on the limiting spot size at large values of the magnetic gradient are discussed. The observation of such small sizes requires a high spatial resolution of the position-sensitive detector. A new electron optical device is described, which images the secondary electron source generated by the impact of the atomic beam on a metallic electrode (detection in real time). Magnifications as high as 65 are accessible, leading to a better than 100 nm resolution of the atomic beam profile when a position-sensitive detector of a few µm resolution is used. Geometric and chromatic aberrations are discussed and, according to simulations, they do not significantly deteriorate the resolution.

  15. On the combination of a low energy hydrogen atom beam with a cold multipole ion trap

    Energy Technology Data Exchange (ETDEWEB)

    Borodi, Gheorghe

    2008-12-09

    The first part of the activities of this thesis was to develop a sophisticated ion storage apparatus dedicated to study chemical processes with atomic hydrogen. The integration of a differentially pumped radical beam source into an existing temperature variable 22- pole trapping machine has required major modifications. Since astrophysical questions have been in the center of our interest, the introduction first gives a short overview of astrophysics and -chemistry. The basics of ion trapping in temperature variable rf traps is well-documented in the literature; therefore, the description of the basic instrument (Chapter 2) is kept rather short. Much effort has been put into the development of an intense and stable source for hydrogen atoms the kinetic energy of which can be changed. Chapter 3 describes this module in detail with emphasis on the integration of magnetic hexapoles for guiding the atoms and special treatments of the surfaces for reducing H-H recombination. Due to the unique sensitivity of the rf ion trapping technique, this instrument allows one to study a variety of reactions of astrochemical and fundamental interest. The results of this work are summarized in Chapter 4. Reactions of CO{sub 2}{sup +} with hydrogen atoms and molecules have been established as calibration standard for in situ determination of H and H{sub 2} densities over the full temperature range of the apparatus (10 K-300 K). For the first time, reactions of H- and D-atoms with the ionic hydrocarbons CH{sup +}, CH{sub 2}{sup +}, and CH{sub 4}{sup +} have been studied at temperatures of interstellar space. A very interesting, not yet fully understood collision system is the interaction of protonated methane with H. The outlook presents some ideas, how to improve the new instrument and a few reaction systems are mentioned which may be studied next. (orig.)

  16. On the combination of a low energy hydrogen atom beam with a cold multipole ion trap

    International Nuclear Information System (INIS)

    The first part of the activities of this thesis was to develop a sophisticated ion storage apparatus dedicated to study chemical processes with atomic hydrogen. The integration of a differentially pumped radical beam source into an existing temperature variable 22- pole trapping machine has required major modifications. Since astrophysical questions have been in the center of our interest, the introduction first gives a short overview of astrophysics and -chemistry. The basics of ion trapping in temperature variable rf traps is well-documented in the literature; therefore, the description of the basic instrument (Chapter 2) is kept rather short. Much effort has been put into the development of an intense and stable source for hydrogen atoms the kinetic energy of which can be changed. Chapter 3 describes this module in detail with emphasis on the integration of magnetic hexapoles for guiding the atoms and special treatments of the surfaces for reducing H-H recombination. Due to the unique sensitivity of the rf ion trapping technique, this instrument allows one to study a variety of reactions of astrochemical and fundamental interest. The results of this work are summarized in Chapter 4. Reactions of CO2+ with hydrogen atoms and molecules have been established as calibration standard for in situ determination of H and H2 densities over the full temperature range of the apparatus (10 K-300 K). For the first time, reactions of H- and D-atoms with the ionic hydrocarbons CH+, CH2+, and CH4+ have been studied at temperatures of interstellar space. A very interesting, not yet fully understood collision system is the interaction of protonated methane with H. The outlook presents some ideas, how to improve the new instrument and a few reaction systems are mentioned which may be studied next. (orig.)

  17. Average Dissipative and Dipole Forces on a Three-Level Atom in a Laguerre-Gaussian Beam

    Institute of Scientific and Technical Information of China (English)

    WANG Zheng-Ling; YIN Jian-Ping

    2005-01-01

    @@ By means of the optical Bloch equations based on the atomic density matrix elements, the general expressions of the average dissipative force, dipole force and the mechanical torque acting on a A-configuration three-level atom in a linearly-polarized Laguerre-Gaussian beam (LGB) with an angular momentum of lh are derived, and the general properties of the average dissipative and dipole force on the three-level atom in the linearly-polarized LGB are analysed. We find a resonant property (with two resonant peaks) of the dissipative force and a non-resonant property (with two pairs of non-resonant peaks) of the dipole force on the three-level atom, which are completely different from those on the two-level atom. Our study also shows that all of general expressions on the three-level atom will be simplified to those on the two-level atom in the approximation of large detuning.

  18. A method for elemental analysis of bones by recoiling atoms in heavy ion beams

    International Nuclear Information System (INIS)

    This contribution is the first attempt to analyse the elemental composition of bones by the recoil atoms in heavy ion beams. The aim of this study was to observe differences in light elements depth gradients, concentrations and ratios (P/Ca, Mg/Ca, N/Ca, Li/Ca) of different human femoral bone compartment: cortical bone (C sample) and trabecular (T sample) bone. The differences could be linked to the function of these areas. An interesting feature concerning lithium has to be pointed out. Lithium continues to be a substance of interest as a potential therapeutic agent in a number of blood disorders as well as a very effective experimental agent to understand the basic biochemical and pharmacological properties that regulate cellular proliferation and differentiation. The first method of analysing and profiling of light elements by recoil atoms in heavy ion beams by using an ionization ΔE, E ionization chamber, was described in a previous paper. In this paper a 32 S beam accelerated at the Van de Graaff Tandem Accelerator was used. Further developing of this method has been presented. It was shown that the monitoring problem can be solved by using beams of ion substantially heavier than the sample to be analysed. For the analysis of bones an 127 I beam has been used. The ΔE,E ionization chamber has been built according to a recent patent. By introducing a getter in the compartment 7 of the chamber one could work in conditions of high purity of the gas inside the chamber. The entrance window of the chamber was made of mylar 2 μm thick. Very good stability of the chamber has been obtained over long runs, ∼ 5 hours, in conditions of closed circuit of the gas. Results are presented. In conclusion: 1) A large difference between the normal sample N and the osteoporotic samples T and C for the Mg/Ca ratio has been found; 2) A very high concentration of Li was observed in the T sample. (authors)

  19. Selective atomic layer deposition with electron-beam patterned self-assembled monolayers

    International Nuclear Information System (INIS)

    The authors selectively deposited nanolines of titanium oxide (TiO2) through atomic layer deposition (ALD) using an octadecyltrichlorosilane (OTS) self-assembled monolayer (SAM) as a nucleation inhibition layer. Electron-beam (e-beam) patterning is used to prepare nanoline patterns in the OTS SAM on SiO2/Si substrates suitable for selective ALD. The authors have investigated the effect of an e-beam dose on the pattern width of the selectively deposited TiO2 lines. A high dose (e.g., 20 nC/cm) causes broadening of the linewidth possibly due to scattering, while a low dose (e.g., 5 nC/cm) results in a low TiO2 deposition rate because of incomplete exposure of the OTS SAMs. The authors have confirmed that sub-30 nm isolated TiO2 lines can be achieved by selective ALD combined with OTS patterned by EBL at an accelerating voltage of 2 kV and line dose of 10 nC/cm. This research offers a new approach for patterned gate dielectric layer fabrication, as well as potential applications for nanosensors and solar cells.

  20. Energy variable monoenergetic positron beam study of oxygen atoms in Czochralski grown Si

    International Nuclear Information System (INIS)

    A monoenergetic positron beam has been used to investigate the state of interstitial oxygen in Czochralski-grown Si with the coverage of SiO2 (100 nm) and poly-Si (200 nm)/SiO2 (100 nm), respectively. It was found that (i) the growth of SiO2 gives rise to a strong Doppler broadening of positron annihilation radiations in the bulk of Si, (ii) such a broadening can be recovered to the original level by annealing at 450degC, by the removal of overlayers using chemical etching and long-term aging at room temperature, (iii) the film stress over the CZ-grown Si is responsible for the rearrangement of oxygen atoms in S and (iv) only tensile stress gives rise to the clustering of oxygen atoms. The observed broadening was assigned to arise from the positron trapping by oxygen interstitial clusters. It was concluded that film stress is responsible for the rearrangement of oxygen atoms in CZ-grown Si. (author)

  1. Coherent and non coherent atom optics experiment with an ultra-narrow beam of metastable rare gas atoms; Experiences d'optique atomique coherente ou non avec un jet superfin d'atomes metastables de gaz rares

    Energy Technology Data Exchange (ETDEWEB)

    Grucker, J

    2007-12-15

    In this thesis, we present a new type of atomic source: an ultra-narrow beam of metastable atoms produced by resonant metastability exchange inside a supersonic beam of rare gas atoms. We used the coherence properties of this beam to observe the diffraction of metastable helium, argon and neon atoms by a nano-transmission grating and by micro-reflection-gratings. Then, we evidenced transitions between Zeeman sublevels of neon metastable {sup 3}P{sub 2} state due to the quadrupolar part of Van der Waals potential. After we showed experimental proofs of the observation of this phenomenon, we calculated the transition probabilities in the Landau - Zener model. We discussed the interest of Van der Waals - Zeeman transitions for atom interferometry. Last, we described the Zeeman cooling of the supersonic metastable argon beam ({sup 3}P{sub 2}). We have succeeded in slowing down atoms to speeds below 100 m/s. We gave experimental details and showed the first time-of-flight measurements of slowed atoms.

  2. An ultra-low energy (30-200 eV) ion-atomic beam source for ion-beam-assisted deposition in ultrahigh vacuum.

    Science.gov (United States)

    Mach, Jindrich; Samoril, Tomás; Voborný, Stanislav; Kolíbal, Miroslav; Zlámal, Jakub; Spousta, Jirí; Dittrichová, Libuse; Sikola, Tomás

    2011-08-01

    The paper describes the design and construction of an ion-atomic beam source with an optimized generation of ions for ion-beam-assisted deposition under ultrahigh vacuum (UHV) conditions. The source combines an effusion cell and an electron impact ion source and produces ion beams with ultra-low energies in the range from 30 eV to 200 eV. Decreasing ion beam energy to hyperthermal values (≈10(1) eV) without loosing optimum ionization conditions has been mainly achieved by the incorporation of an ionization chamber with a grid transparent enough for electron and ion beams. In this way the energy and current density of nitrogen ion beams in the order of 10(1) eV and 10(1) nA/cm(2), respectively, have been achieved. The source is capable of growing ultrathin layers or nanostructures at ultra-low energies with a growth rate of several MLs/h. The ion-atomic beam source will be preferentially applied for the synthesis of GaN under UHV conditions. PMID:21895238

  3. Transverse coherence of a natural metastable-atom nozzle beam : Scattering and van der Waals-Zeeman transitions

    Science.gov (United States)

    Baudon, J.; Karam, J.-C.; Boustimi, M.; Perales, F.; Bocvarski, V.; Vassilev, G.; Reinhardt, J.; Mainos, C.; Grucker, J.; Wipf, N.; Robert, J.

    2004-12-01

    By use of the resonant metastability-exchange process, a metastable-atom beam possessing all genuine qualities of a " natural " ground-state atom nozzle beam is prepared. Owing to the angular narrowness (0.35 mrad) and smallness of the effective source diameter (15 μm) of this beam, the scattering of metastable atoms by a silicon-nitride nano-slit grating is investigated in detail, in a partially coherent regime. The elastic scattering exhibits high-order diffraction peaks combined with a standard van der Waals deflection effect. When a static magnetic field is present, surface-induced exo-energetic transitions among Zeeman sub-levels are observed.

  4. Chemical reaction of sputtered Cu film with PI modified by low energy reactive atomic beam

    International Nuclear Information System (INIS)

    Polyimide (PMDA-ODA) surface was irradiated by low energy reactive atomic beam with energy 160-180 eV to enhance the adhesion with metal Cu film. O2+ and N2+ ions were irradiated at the fluence from 5 x 1015 to 1 x 1018 cm-2. Wetting angle 78o of distilled deionized (DI) water for bare PI was greatly reduced down to 2-4o after critical ion flounce, and the surface energy was increased from 37 to 81.2 erg/cm. From the analysis of O 1s core-level XPS spectra, such improvement seemed to result from the increment of hydrophilic carbonyl oxygen content on modified PI surface. To see more carefully correlation of the peel strength with interfacial reaction between Cu and PI, flexible copper clad laminate with Cu (9 μm)/Cu (200 nm) on modified PI substrate (25 μm) was fabricated by successive sputtering and electroplating. Firstly, peel strength was measured by using t-test and it was largely increased from 0.2 to 0.5 kgf/cm for Ar+ only irradiated PI to 0.72-0.8 kgf/cm for O2+ or N2O+ irradiated PI. Chemical reaction at the interface was reasoned by analyzing C 1s, O 1s, N 1s, and Cu 2p core-level X-ray photoelectron spectroscopy over the as-cleaved Cu-side and PI side surface through depth profiling. From the C 1s spectra of cleaved Cu-side, by the electron transfer from Cu to carbonyl oxygen, carbonyl carbon atom became less positive and as a result shifted to lower binding energy not reaching the binding energy of C2 and C3. The binding energy shift of the peak C4 as small as 1.7 eV indicates that carbonyl oxygen atoms were not completely broken. From the analysis of the O 1s spectra, it was found that new peak at 530.5 eV (O3) was occurred and the increased area of the peak O3 was almost the same with reduced area of the peak carbonyl oxygen peak O1. Since there was no change in the relative intensity of ether oxygen (O2) to carbonyl oxygen (O1), and thus O3 was believed to result from Cu oxide formation via a local bonding of Cu with carbonyl oxygen atoms

  5. Time dependence of desorbed ground-state lithium atoms following pulsed-electron-beam irradiation of lithium fluoride

    International Nuclear Information System (INIS)

    Recent experiments have shown that during the irradiation of lithium fluoride crystals by a chopped electron beam the signal of desorbed ground-state lithium atoms continues for times up to seconds in the beam-off period. A quantitative model is presented which connects the desorption of lithium atoms with the diffusion of lithium fluoride F centers to the surface. The model thus introduces a new source of time delay (F-center diffusion) in the desorption of ground-state metal atoms from alkali halides. Formerly it has been supposed that the delay occurred entirely during the surface desorption step. The model fits the experimental data very well, and should be applicable to other similar systems. For the cases considered here, F-center diffusion turns out to be the primary source of delay in the Li-atom signal. The model suggests some new directions for investigation

  6. Optical Guiding of Trapped Atoms by a Blue-Detuned Hollow Laser Beam in the Horizontal Direction

    Institute of Scientific and Technical Information of China (English)

    JIANG Kai-Jun; LI Ke; WANG Jin; ZHAN Ming-Sheng

    2005-01-01

    @@ Optical guiding of 85 Rb atoms in a magneto-optical trap (MOT) by a blue-detuned horizontal hollow laser beam is demonstrated experimentally. The guiding efficiency and the velocity distribution of the guided atoms are found to have strong dependence on the detuning of the guiding laser. In particular, the optimum guiding occurs when the blue detuning of the hollow laser beam is approximately equal to the hyperfine structure splitting of the 85Rb ground states, in good agreement with the theoretical analysis based on a three-level model.

  7. Atomic layer deposition of an Al2O3 dielectric on ultrathin graphite by using electron beam irradiation

    Institute of Scientific and Technical Information of China (English)

    Jiang Ran; Meng Lingguo; Zhang Xijian; Hyung-Suk Jung; Cheol Seong Hwang

    2012-01-01

    Atomic layer deposition ofan Al2O3 dielectric on ultrathin graphite is studied in order to investigate the integration of a high k dielectric with graphite-based substrates.Electron beam irradiation on the graphite surface is followed by a standard atomic layer deposition of Al2O3.Improvement of the Al2O3 layer deposition morphology was observed when using this radiation exposure on graphite.This result may be attributed to the amorphous change of the graphite layers during electron beam irradiation.

  8. Quantitative measurements of electromechanical response with a combined optical beam and interferometric atomic force microscope

    Energy Technology Data Exchange (ETDEWEB)

    Labuda, Aleksander; Proksch, Roger [Asylum Research an Oxford Instruments Company, Santa Barbara, California 93117 (United States)

    2015-06-22

    An ongoing challenge in atomic force microscope (AFM) experiments is the quantitative measurement of cantilever motion. The vast majority of AFMs use the optical beam deflection (OBD) method to infer the deflection of the cantilever. The OBD method is easy to implement, has impressive noise performance, and tends to be mechanically robust. However, it represents an indirect measurement of the cantilever displacement, since it is fundamentally an angular rather than a displacement measurement. Here, we demonstrate a metrological AFM that combines an OBD sensor with a laser Doppler vibrometer (LDV) to enable accurate measurements of the cantilever velocity and displacement. The OBD/LDV AFM allows a host of quantitative measurements to be performed, including in-situ measurements of cantilever oscillation modes in piezoresponse force microscopy. As an example application, we demonstrate how this instrument can be used for accurate quantification of piezoelectric sensitivity—a longstanding goal in the electromechanical community.

  9. Crossed-beam DC slice imaging of fluorine atom reactions with linear alkanes

    International Nuclear Information System (INIS)

    We report the reaction dynamics of F atom with selected alkanes studied by crossed beam scattering with DC slice ion imaging. The target alkanes are propane, n-butane, and n-pentane. The product alkyl radicals are probed by 157 nm single photon ionization following reaction at a collision energy of ∼10 kcal mol−1. The analyzed data are compared with the corresponding theoretical studies. Reduced translational energy distributions for each system show similar trends with little of the reaction exoergicity appearing in translation. However, the pentane reaction shows a somewhat smaller fraction of available energy in translation than the other two, suggesting greater energy channeled into pentyl internal degrees of freedom. The center-of-mass angular distributions all show backscattering as well as sharp forward scattering that decreases in relative intensity with the size of the molecule. Possible reasons for these trends are discussed

  10. Crossed-beam DC slice imaging of fluorine atom reactions with linear alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yuanyuan; Kamasah, Alexander; Joalland, Baptiste; Suits, Arthur G., E-mail: asuits@chem.wayne.edu [Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202 (United States)

    2015-05-14

    We report the reaction dynamics of F atom with selected alkanes studied by crossed beam scattering with DC slice ion imaging. The target alkanes are propane, n-butane, and n-pentane. The product alkyl radicals are probed by 157 nm single photon ionization following reaction at a collision energy of ∼10 kcal mol{sup −1}. The analyzed data are compared with the corresponding theoretical studies. Reduced translational energy distributions for each system show similar trends with little of the reaction exoergicity appearing in translation. However, the pentane reaction shows a somewhat smaller fraction of available energy in translation than the other two, suggesting greater energy channeled into pentyl internal degrees of freedom. The center-of-mass angular distributions all show backscattering as well as sharp forward scattering that decreases in relative intensity with the size of the molecule. Possible reasons for these trends are discussed.

  11. Candlestick oven with a silica wick provides an intense collimated cesium atomic beam

    Science.gov (United States)

    Pailloux, A.; Alpettaz, T.; Lizon, E.

    2007-02-01

    This article shows that readily available glass and silica fibers and braids are suitable capillary structure for recirculating ovens, such as candlestick ovens, becoming then an alternative wick material to conventional metal based capillary structures. In order to study wettability and capillarity of metallic liquid cesium on borosilicate and silica microstructures, samples were selected, prepared, and tested experimentally. The contact angle of cesium on silica glass was roughly measured: θ =35°±10°. A commercially available silica braid was then introduced inside a candlestick oven to transfer the metallic liquid cesium from the cold reservoir to the hot emission point of the candlestick. A collimated cesium atomic beam of intensity of 2×1016at./ssr was obtained, stable and reproducible. Furthermore, this modified oven is easy to handle daily.

  12. Synthesis and characterization of Au-alumina nanocomposites prepared by atom beam co-sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, Manisha; Annapoorni, S. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Agarwal, D.C.; Avasthi, D.K. [Inter University Accelerator Centre, P.O. Box 10502, New Delhi 110067 (India); Mohapatra, S. [School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi 110075 (India); Pivin, J.C. [CSNSM, IN2P3-CNRS, Batiment 108, 1405 Orsay Campus (France)

    2012-12-15

    Nanocomposite thin films of Au-alumina with varying Au contents were synthesized by atom beam co-sputtering. The Au content and the thickness of nanocomposite films were determined by Rutherford backscattering spectrometry. Transmission electron microscopy studies reveal the presence of Au nanoparticles with bimodal size distribution in nanocomposites for lower Au content. Overlapping Au nanoparticles were observed for higher Au content. The increase in size of Au nanocrystals is observed with increase in Au concentration as also evident by glancing angle X-ray diffraction studies. Ultraviolet (UV)-visible absorption studies revealed surface plasmon resonance (SPR) peak which showed a red shift from 519 to 602 nm with increasing Au content of the nanocomposites. Preliminary study exploring the interaction between Au nanoparticles in the nanocomposites and bovine serum albumin (BSA) showed the Au nanoparticles to be BSA sensitive, indicating their possible applications in biosensors. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Quantitative measurements of electromechanical response with a combined optical beam and interferometric atomic force microscope

    International Nuclear Information System (INIS)

    An ongoing challenge in atomic force microscope (AFM) experiments is the quantitative measurement of cantilever motion. The vast majority of AFMs use the optical beam deflection (OBD) method to infer the deflection of the cantilever. The OBD method is easy to implement, has impressive noise performance, and tends to be mechanically robust. However, it represents an indirect measurement of the cantilever displacement, since it is fundamentally an angular rather than a displacement measurement. Here, we demonstrate a metrological AFM that combines an OBD sensor with a laser Doppler vibrometer (LDV) to enable accurate measurements of the cantilever velocity and displacement. The OBD/LDV AFM allows a host of quantitative measurements to be performed, including in-situ measurements of cantilever oscillation modes in piezoresponse force microscopy. As an example application, we demonstrate how this instrument can be used for accurate quantification of piezoelectric sensitivity—a longstanding goal in the electromechanical community

  14. Tunable atomic force microscopy bias lithography on electron beam induced carbonaceous platforms

    Directory of Open Access Journals (Sweden)

    Narendra Kurra

    2013-09-01

    Full Text Available Tunable local electrochemical and physical modifications on the carbonaceous platforms are achieved using Atomic force microscope (AFM bias lithography. These carbonaceous platforms are produced on Si substrate by the technique called electron beam induced carbonaceous deposition (EBICD. EBICD is composed of functionalized carbon species, confirmed through X-ray photoelectron spectroscopy (XPS analysis. AFM bias lithography in tapping mode with a positive tip bias resulted in the nucleation of attoliter water on the EBICD surface under moderate humidity conditions (45%. While the lithography in the contact mode with a negative tip bias caused the electrochemical modifications such as anodic oxidation and etching of the EBICD under moderate (45% and higher (60% humidity conditions respectively. Finally, reversible charge patterns are created on these EBICD surfaces under low (30% humidity conditions and investigated by means of electrostatic force microscopy (EFM.

  15. Collisional and Radiative Processes in Adiabatic Deceleration, Deflection, and Off-Axis Trapping of a Rydberg Atom Beam

    International Nuclear Information System (INIS)

    A supersonic beam of Rydberg hydrogen atoms has been adiabatically deflected by 90 deg., decelerated to zero velocity in less than 25 μs, and loaded into an electric trap. The deflection has allowed the suppression of collisions with atoms in the trailing part of the gas pulse. The processes leading to trap losses, i.e., fluorescence to the ground state, and transitions and ionization induced by blackbody radiation have been monitored over several milliseconds and quantitatively analyzed.

  16. Selective population of ground terms in /sup 14/N atoms after ion-beam--surface interaction at grazing incidence

    Energy Technology Data Exchange (ETDEWEB)

    Winter, H.; Langheim, M.; Schirmacher, A.; Zimny, R.; Andra, H.J.

    1984-04-02

    The orientation of angular momenta in the ground terms of /sup 14/N atoms after the interaction of 350-keV /sup 14/N/sup +/ ions with a solid surface at grazing incidence is investigated by a Zeeman quantum-beat technique. After the ion-solid interaction, a term-selective and highly polarized fast beam of nitrogen atoms is observed. The phenomenon is interpreted in terms of a Pauli-principle--induced selective population.

  17. 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

  18. Gate-Tunable Atomically Thin Lateral MoS2 Schottky Junction Patterned by Electron Beam.

    Science.gov (United States)

    Katagiri, Y; Nakamura, T; Ishii, A; Ohata, C; Hasegawa, M; Katsumoto, S; Cusati, T; Fortunelli, A; Iannaccone, G; Fiori, G; Roche, S; Haruyama, J

    2016-06-01

    Among atomically thin two-dimensional (2D) materials, molybdenum disulfide (MoS2) is attracting considerable attention because of its direct bandgap in the 2H-semiconducting phase. On the other hand, a 1T-metallic phase has been revealed, bringing complementary application. Recently, thanks to top-down fabrication using electron beam (EB) irradiation techniques, in-plane 1T-metal/2H-semiconductor lateral (Schottky) MoS2 junctions were demonstrated, opening a path toward the co-integration of active and passive two-dimensional devices. Here, we report the first transport measurements evidencing the formation of a MoS2 Schottky barrier (SB) junction with barrier height of 0.13-0.18 eV created at the interface between EB-irradiated (1T)/nonirradiated (2H) regions. Our experimental findings, supported by state-of-the-art simulation, reveal unique device fingerprint of SB-based field-effect transistors made from atom-thin 1T layers. PMID:27152475

  19. Light and/or atomic beams to detect ultraweak gravitational effects

    Directory of Open Access Journals (Sweden)

    Tartaglia Angelo

    2014-06-01

    Full Text Available We shall review the opportunities lent by ring lasers and atomic beams interferometry in order to reveal gravitomagnetic effects on Earth. Both techniques are based on the asymmetric propagation of waves in the gravitational field of a rotating mass; actually the times of flight for co- or counter-rotating closed paths turn out to be different. After discussing properties and limitations of the two approaches we shall describe the proposed GINGER experiment which is being developed for the Gran Sasso National Laboratories in Italy. The experimental apparatus will consist of a three-dimensional array of square rings, 6m × 6m, that is planned to reach a sensitivity in the order of 1prad/√Hertz or better. This sensitivity would be one order of magnitude better than the best existing ring, which is the G-ring in Wettzell, Bavaria, and would allow for the terrestrial detection of the Lense-Thirring effect and possibly of deviations from General Relativity. The possibility of using either the ring laser approach or atomic interferometry in a space mission will also be considered. The technology problems are under experimental study using both the German G-ring and the smaller G-Pisa ring, located at the Gran Sasso.

  20. Atoms

    International Nuclear Information System (INIS)

    Completed by recent contributions on various topics (atoms and the Brownian motion, the career of Jean Perrin, the evolution of atomic physics since Jean Perrin, relationship between scientific atomism and philosophical atomism), this book is a reprint of a book published at the beginning of the twentieth century in which the author addressed the relationship between atomic theory and chemistry (molecules, atoms, the Avogadro hypothesis, molecule structures, solutes, upper limits of molecular quantities), molecular agitation (molecule velocity, molecule rotation or vibration, molecular free range), the Brownian motion and emulsions (history and general features, statistical equilibrium of emulsions), the laws of the Brownian motion (Einstein's theory, experimental control), fluctuations (the theory of Smoluchowski), light and quanta (black body, extension of quantum theory), the electricity atom, the atom genesis and destruction (transmutations, atom counting)

  1. l- and n-changing collisions during interaction of a pulsed beam of Li Rydberg atoms with CO2

    International Nuclear Information System (INIS)

    The pulsed Li atomic beam produced in our experiment is based on controlled transversely-excited-atmospheric CO2 laser-induced ablation of a Li metal target. The atomic beam is propagated in vacuum or in CO2 gas at low pressure. Atoms in the beam are probed by laser-induced fluorescence spectroscopy. This allows the determination of time-of-flight and velocity distributions. Li Rydberg states (n=5--13) are populated in the beam by two-step pulsed-laser excitation. The excited atoms interact with CO2 molecules. l- and n-changing cross sections are deduced from the time evolution of the resonant or collision-induced fluorescence following this selective excitation. l-changing cross sections of the order of 104 A2 are measured; they increase with n as opposed to the plateau observed for Li/sup */ colliding with a diatomic molecule. This behavior is qualitatively well explained in the framework of the free-electron model. n yields n' changing processes with large cross sections (10--100 A2) are also observed even in the case of large electronic energy change (ΔE/sub nn'/>103 cm/sup -1/). These results can be interpreted in terms of resonant-electronic to vibrational energy transfers between Li Rydberg states and CO2 vibrational modes

  2. l- and n-changing collisions during interaction of a pulsed beam of Li Rydberg atoms with CO2

    Science.gov (United States)

    Dubreuil, B.; Harnafi, M.

    1989-07-01

    The pulsed Li atomic beam produced in our experiment is based on controlled transversely-excited-atmospheric CO2 laser-induced ablation of a Li metal target. The atomic beam is propagated in vacuum or in CO2 gas at low pressure. Atoms in the beam are probed by laser-induced fluorescence spectroscopy. This allows the determination of time-of-flight and velocity distributions. Li Rydberg states (n=5-13) are populated in the beam by two-step pulsed-laser excitation. The excited atoms interact with CO2 molecules. l- and n-changing cross sections are deduced from the time evolution of the resonant or collision-induced fluorescence following this selective excitation. l-changing cross sections of the order of 104 AṦ are measured; they increase with n as opposed to the plateau observed for Li* colliding with a diatomic molecule. This behavior is qualitatively well explained in the framework of the free-electron model. n-->n' changing processes with large cross sections (10-100 AṦ) are also observed even in the case of large electronic energy change (ΔEnn'>103 cm-1). These results can be interpreted in terms of resonant-electronic to vibrational energy transfers between Li Rydberg states and CO2 vibrational modes.

  3. Detection of slow atoms confined in a Cesium vapor cell by spatially separated pump and probe laser beams

    CERN Document Server

    Todorov, Petko; Maurin, Isabelle; Saltiel, Solomon; Bloch, Daniel

    2013-01-01

    The velocity distribution of atoms in a thermal gas is usually described through a Maxwell-Boltzman distribution of energy, and assumes isotropy. As a consequence, the probability for an atom to leave the surface under an azimuth angle {\\theta} should evolve as cos {\\theta}, in spite of the fact that there is no microscopic basis to justify such a law. The contribution of atoms moving at a grazing incidence towards or from the surface, i.e. atoms with a small normal velocity, here called "slow" atoms, reveals essential in the development of spectroscopic methods probing a dilute atomic vapor in the vicinity of a surface, enabling a sub-Doppler resolution under a normal incidence irradiation. The probability for such "slow" atoms may be reduced by surface roughness and atom-surface interaction. Here, we describe a method to observe and to count these slow atoms relying on a mechanical discrimination, through spatially separated pump and probe beams. We also report on our experimental progresses toward such a g...

  4. Customized atomic force microscopy probe by focused-ion-beam-assisted tip transfer

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Andrew; Butte, Manish J., E-mail: manish.butte@stanford.edu [Department of Pediatrics, Division of Immunology, Allergy and Rheumatology, Stanford University, Stanford, California 94305 (United States)

    2014-08-04

    We present a technique for transferring separately fabricated tips onto tipless atomic force microscopy (AFM) cantilevers, performed using focused ion beam-assisted nanomanipulation. This method addresses the need in scanning probe microscopy for certain tip geometries that cannot be achieved by conventional lithography. For example, in probing complex layered materials or tall biological cells using AFM, a tall tip with a high-aspect-ratio is required to avoid artifacts caused by collisions of the tip's sides with the material being probed. We show experimentally that tall (18 μm) cantilever tips fabricated by this approach reduce squeeze-film damping, which fits predictions from hydrodynamic theory, and results in an increased quality factor (Q) of the fundamental flexural mode. We demonstrate that a customized tip's well-defined geometry, tall tip height, and aspect ratio enable improved measurement of elastic moduli by allowing access to low-laying portions of tall cells (T lymphocytes). This technique can be generally used to attach tips to any micromechanical device when conventional lithography of tips cannot be accomplished.

  5. Collisional and radiative processes in adiabatic deceleration, deflection, and off-axis trapping of a Rydberg atom beam.

    Science.gov (United States)

    Seiler, Ch; Hogan, S D; Schmutz, H; Agner, J A; Merkt, F

    2011-02-18

    A supersonic beam of Rydberg hydrogen atoms has been adiabatically deflected by 90°, decelerated to zero velocity in less than 25  μs, and loaded into an electric trap. The deflection has allowed the suppression of collisions with atoms in the trailing part of the gas pulse. The processes leading to trap losses, i.e., fluorescence to the ground state, and transitions and ionization induced by blackbody radiation have been monitored over several milliseconds and quantitatively analyzed. PMID:21405512

  6. A three-dimensional relaxation model for calculation of atomic mixing and topography changes induces by ion beams

    International Nuclear Information System (INIS)

    A simple model for three-dimensional material relaxation associated with atomic mixing is presented. The relaxation of the solid to accommodate the extra effective displacement volume Ω of an implanted or relocated atom is modelled by treating the surrounding solid as an incompressible medium. This leads to a tractable general formalism which can be used to predict implant distribution and changes in surface topography induced by ion beams, both in monatomic and multicomponent targets. The two-component case is discussed in detail. (orig.)

  7. An electrostatic glass actuator for ultrahigh vacuum: A rotating light trap for continuous beams of laser-cooled atoms.

    Science.gov (United States)

    Füzesi, F; Jornod, A; Thomann, P; Plimmer, M D; Dudle, G; Moser, R; Sache, L; Bleuler, H

    2007-10-01

    This article describes the design, characterization, and performance of an electrostatic glass actuator adapted to an ultrahigh vacuum environment (10(-8) mbar). The three-phase rotary motor is used to drive a turbine that acts as a velocity-selective light trap for a slow continuous beam of laser-cooled atoms. This simple, compact, and nonmagnetic device should find applications in the realm of time and frequency metrology, as well as in other areas of atomic, molecular physics and elsewhere. PMID:17979408

  8. Generations of dark hollow beams and their applications in laser cooling of atoms and all optical-type Bose-Einstein condensation

    Institute of Scientific and Technical Information of China (English)

    印建平; 高伟建; 王海峰; 龙全; 王育竹

    2002-01-01

    We report on a new experimental result to generate dark hollow beams by using a geometric optical method.We propose two new methods to produce focused and localized hollow laser beams by using π-phase plates. UsingMonte-Carlo simulations, we have studied the Sisyphus cooling of alkali atoms in pyramidal hollow beam gravito-opticaltraps. We discuss some potential applications of the dark hollow beams in atom optics and the preparation of an alloptically-cooled and optically-trapped atomic Bose-Einstein condensation (BEC).Our research shows that an ultracoldatomic sample with a temperature of ~ 2μK can be obtained in the pyramidal hollow beam dipole trap and an alloptical-type BEC may be realized in a far blue-detuned, hollow beam trap.

  9. Development of the negative ion beams relevant to ITER and JT-60SA at Japan Atomic Energy Agency

    Energy Technology Data Exchange (ETDEWEB)

    Hanada, M., E-mail: hanada.masaya@jaea.go.jp; Kojima, A.; Tobari, H.; Nishikiori, R.; Hiratsuka, J.; Kashiwagi, M.; Umeda, N.; Yoshida, M.; Ichikawa, M.; Watanabe, K. [Japan Atomic Energy Agency, 801-1 Mukouyama, Naka-shi, Ibaraki-ken 319-0913 (Japan); Yamano, Y. [Saitama University, Saitama, Saitama-ken 338-8570 (Japan); Grisham, L. R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2016-02-15

    In order to realize negative ion sources and accelerators to be applicable to International Thermonuclear Experimental Reactor and JT-60 Super Advanced, a large cesium (Cs)-seeded negative ion source and a multi-aperture and multi-stage electric acceleration have been developed at Japan Atomic Energy Agency (JAEA). Long pulse production and acceleration of the negative ion beams have been independently carried out. The long pulse production of the high current beams has achieved 100 s at the beam current of 15 A by modifying the JT-60 negative ion source. The pulse duration time is increased three times longer than that before the modification. As for the acceleration, a pulse duration time has been also extended two orders of magnitudes from 0.4 s to 60 s. The developments of the negative ion source and acceleration at JAEA are well in progress towards the realization of the negative ion sources and accelerators for fusion applications.

  10. Development of the negative ion beams relevant to ITER and JT-60SA at Japan Atomic Energy Agency.

    Science.gov (United States)

    Hanada, M; Kojima, A; Tobari, H; Nishikiori, R; Hiratsuka, J; Kashiwagi, M; Umeda, N; Yoshida, M; Ichikawa, M; Watanabe, K; Yamano, Y; Grisham, L R

    2016-02-01

    In order to realize negative ion sources and accelerators to be applicable to International Thermonuclear Experimental Reactor and JT-60 Super Advanced, a large cesium (Cs)-seeded negative ion source and a multi-aperture and multi-stage electric acceleration have been developed at Japan Atomic Energy Agency (JAEA). Long pulse production and acceleration of the negative ion beams have been independently carried out. The long pulse production of the high current beams has achieved 100 s at the beam current of 15 A by modifying the JT-60 negative ion source. The pulse duration time is increased three times longer than that before the modification. As for the acceleration, a pulse duration time has been also extended two orders of magnitudes from 0.4 s to 60 s. The developments of the negative ion source and acceleration at JAEA are well in progress towards the realization of the negative ion sources and accelerators for fusion applications. PMID:26932050

  11. Multiple-composition hyperthermal atomic beams formed by a laser-induced plasma for planetary environmental studies

    International Nuclear Information System (INIS)

    A multiple-composition beam with a velocity of 8 km s−1 was formed using a laser detonation source in order to simulate the physical and chemical effects of neutral gas collisions on a material in the sub-low earth orbit (LEO). A premixed target gas was applied in the laser detonation beam technique. It was found that atoms of different masses, O and Ar for Ar + O2 target gas, are accelerated to similar velocities, i.e. different translational energies. Promotion of O2 decomposition is confirmed by using a mixed gas target. It is concluded that the multiple-composition beam obtained using a mixed target gas is suitable for simulating a neutral gas environment in the sub-LEO region. (paper)

  12. Electric field strength measurements in a megavolt vacuum diode using laser induced fluorescence of an atomic beam

    International Nuclear Information System (INIS)

    A combined technique of an atomic beam probing and laser-induced fluorescence spectroscopy (LIFABS) is applied for measuring of local electric field in a 1 MV, 100 kJ, 4 μsec electron diode. Laser-produced lithium beam is stepwise excited by two resonant wide-band laser beams. Stark-splitted spontaneous emission from n=4 level is detected with a polychromator. Time dependence of the electric field was inferred from splitting of the 460.3 nm lithium line. The electric field strength F grows during a pulse from 160 to 260 kV/cm in the center of a 6 cm gap. By comparing calculated and experimental F-values, expansion of the emission boundaries of the cathode and anode plasmas was reconstructed

  13. Development of the negative ion beams relevant to ITER and JT-60SA at Japan Atomic Energy Agency

    Science.gov (United States)

    Hanada, M.; Kojima, A.; Tobari, H.; Nishikiori, R.; Hiratsuka, J.; Kashiwagi, M.; Umeda, N.; Yoshida, M.; Ichikawa, M.; Watanabe, K.; Yamano, Y.; Grisham, L. R.

    2016-02-01

    In order to realize negative ion sources and accelerators to be applicable to International Thermonuclear Experimental Reactor and JT-60 Super Advanced, a large cesium (Cs)-seeded negative ion source and a multi-aperture and multi-stage electric acceleration have been developed at Japan Atomic Energy Agency (JAEA). Long pulse production and acceleration of the negative ion beams have been independently carried out. The long pulse production of the high current beams has achieved 100 s at the beam current of 15 A by modifying the JT-60 negative ion source. The pulse duration time is increased three times longer than that before the modification. As for the acceleration, a pulse duration time has been also extended two orders of magnitudes from 0.4 s to 60 s. The developments of the negative ion source and acceleration at JAEA are well in progress towards the realization of the negative ion sources and accelerators for fusion applications.

  14. Two-color above threshold ionization of atoms and ions in XUV Bessel beams and combined with intense laser light

    CERN Document Server

    Seipt, D; Surzhykov, A; Fritzsche, S

    2016-01-01

    The two-color above-threshold ionization (ATI) of atoms and ions is investigated for a vortex Bessel beam in the presence of a strong near-infrared (NIR) light field. While the photoionization is caused by the photons from the weak but extreme ultra-violet (XUV) vortex Bessel beam, the energy and angular distribution of the photoelectrons and their sideband structure are affected by the plane-wave NIR field. We here explore the energy spectra and angular emission of the photoelectrons in such two-color fields as a function of the size and location of the target (atoms) with regard to the beam axis. In addition, analogue to the circular dichroism in typical two-color ATI experiments with circularly polarized light, we define and discuss seven different dichroism signals for such vortex Bessel beams that arise from the various combinations of the orbital and spin angular momenta of the two light fields. For localized targets, it is found that these dichroism signals strongly depend on the size and position of t...

  15. Growth temperature dependence of the surface segregation of Er atoms in GaAs during molecular beam epitaxy

    International Nuclear Information System (INIS)

    We have quantitatively studied the temperature dependence of the surface segregation of Er atoms in GaAs during molecular beam epitaxy using secondary ion mass spectroscopy. It was found that a significant number of Er atoms segregate to the growing surface at temperatures of 400°C and above and that the segregation decay length is approximately 0.5 µm at 500°C, indicating that the incorporation ratio of Er atoms into GaAs is less than 10-3. In contrast to the growth at higher temperatures, GaAs overlayer growth at a temperature as low as 300°C is effective in suppressing the surface segregation of Er and obtaining δ-doped structures. (author)

  16. Field ionization of helium in a supersonic beam: Kinetic energy of neutral atoms and probability of their field ionization

    International Nuclear Information System (INIS)

    High detection efficiency combined with spatial resolution on a nm-scale makes the field ionization process a promising candidate for spatially resolved neutral particles detection. The effective cross-sectional area σeff can serve as a measure for the effectiveness of such a field ion detector. In the present contribution, we combine quantum-mechanical calculations of the field-modified electron density distribution near the tungsten tip surface and of the resulting local field distributions, performed using the functional integration method, with a classical treatment of the atom trajectories approaching the tip in order to calculate the σeff values for ionization of free He atoms over an apex of a tungsten field emitter tip. The calculated values are compared with experimental data for supersonic He atomic beams at two different temperatures 95 and 298 K.

  17. Atomic retention and near infrared photoluminescence from PbSe nanocrystals fabricated by sequential ion implantation and electron beam annealing

    International Nuclear Information System (INIS)

    Nanocrystals of PbSe have been fabricated in a silicon dioxide matrix by sequential low energy ion implantation followed by an electron beam annealing step. Transmission electron microscopy reveals PbSe nanocrystals with typical sizes between 3 and 10 nm in the sub-surface region. Rutherford Backscattering Spectrometry has been used to study the total atomic retention, as a function of implanted atoms, following annealing. Photoluminescence was observed in various samples, at 4 K, as a broad peak between 1.4 and 2.0 μm, with observation of a dependence of the peak wavelength on annealing temperature. Room temperature photoluminescence was observed for samples with a high retention of implanted atoms, demonstrating the importance of nanocrystal density for achieving ambient temperature emission in these systems

  18. Precision spectroscopy of the 2S-4P1/2 transition in atomic hydrogen on a cold thermal beam of optically excited 2S atoms

    International Nuclear Information System (INIS)

    The 'proton size puzzle', i.e. the discrepancy between the values for the proton r.m.s. charge radius deduced from precision spectroscopy of atomic hydrogen and electron-proton-scattering on one side and the value deduced from muonic hydrogen spectroscopy on the other side, has been persisting for more than two years now. Although huge efforts have been put into trying to resolve this discrepancy from experimental and theoretical side, no convincing argument could be found so far. In this talk, we report on a unique precision spectroscopy experiment on atomic hydrogen, which is aiming to bring some light to the hydrogen part of the puzzle: In contrast to any previous high resolution experiment probing a transition frequency between the meta-stable 2S state and a higher lying nL state (n=3,4,6,8,12, L=S,P,D), our measurement of the 2S-4P1/2 transition frequency is the first experiment being performed on a cold thermal beam of hydrogen atoms optically excited to the 2S state. We will discuss how this helps to efficiently suppresses leading systematic effects of previous measurements and present the preliminary results we obtained so far.

  19. Creation evidence of the second non-dispersive Zakharenko wave by helium atomic beams in superfluid helium-II at low temperatures

    Indian Academy of Sciences (India)

    A A Zakharenko

    2007-10-01

    In this work, the experimental results of the creation of the second non-dispersive Zakharenko wave (ph = g ≠ 0) in the negative roton branch (the so-called second sound) of the bulk elementary excitations (BEEs) energy spectra are introduced. Several BEE signals detected by a bolometer situated in the isotopically pure liquid helium-II at low temperatures ∼ 100 mK are shown, which give evidence of negative roton creation in the liquid by helium atomic beams striking the liquid surface. The negative roton signals were clearly distinguished by the following ways: the negative roton signal created by helium atomic beams appeared earlier than the positive roton signal created by the beams, and presence of both positive and negative roton signals together. It is natural that the negative roton creation by the beams requires the 4He-atom energies ∼ 12 K, while the positive roton creation by the atomic beams requires energies ∼ 35 K. Therefore, successive increase in the heater power resulting in an increase in the 4He-atom energies gives solid evidence that the negative rotons are first created in the liquid by the helium atomic beams.

  20. Production, formation, and transport of high-brightness atomic hydrogen beam studies for the relativistic heavy ion collider polarized source upgrade

    Science.gov (United States)

    Kolmogorov, A.; Atoian, G.; Davydenko, V.; Ivanov, A.; Ritter, J.; Stupishin, N.; Zelenski, A.

    2014-02-01

    The RHIC polarized H- ion source had been successfully upgraded to higher intensity and polarization by using a very high brightness fast atomic beam source developed at BINP, Novosibirsk. In this source the proton beam is extracted by a four-grid multi-aperture ion optical system and neutralized in the H2 gas cell downstream from the grids. The proton beam is extracted from plasma emitter with a low transverse ion temperature of ˜0.2 eV which is formed by plasma jet expansion from the arc plasma generator. The multi-hole grids are spherically shaped to produce "geometrical" beam focusing. Proton beam formation and transport of atomic beam were experimentally studied at test bench.

  1. Calculation of a shadow cone formed by scattering of an ion beam from an atom

    International Nuclear Information System (INIS)

    The shadow cone formed by the scattering of ions from an atom was calculated using Moliere potential. Calculated radii of the shadow cone by replacing the Thomas-Fermi radius, a sub(TF), with 0.85 a sub(TF) show a good agreement with an experiment for 1 keV helium ions on a titanium atom. (author)

  2. Production of rare-earth atomic negative ion beams in a cesium-sputter-type negative ion source

    International Nuclear Information System (INIS)

    The desire to study negative ion structure and negative ion-photon interactions has spurred the development of ion sources for use in research and industry. The many different types of negative ion sources available today differ in their characteristics and abilities to produce anions of various species. Thus the importance of choosing the correct type of negative ion source for a particular research or industrial application is clear. In this study, the results of an investigation on the production of beams composed of negatively-charged rare-earth ions from a cylindrical-cathode-geometry, cesium-sputter-type negative ion source are presented. Beams of atomic anions have been observed for most of the first-row rare-earth elements, with typical currents ranging from hundreds of picoamps to several nanoamps

  3. An atomic hydrogen beam to test ASACUSA’s apparatus for antihydrogen spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Diermaier, M., E-mail: martin.diermaier@oeaw.ac.at; Caradonna, P.; Kolbinger, B. [Austrian Academy of Sciences, Stefan Meyer Institute for Subatomic Physics (Austria); Malbrunot, C. [CERN (Switzerland); Massiczek, O.; Sauerzopf, C.; Simon, M. C.; Wolf, M.; Zmeskal, J.; Widmann, E. [Austrian Academy of Sciences, Stefan Meyer Institute for Subatomic Physics (Austria)

    2015-08-15

    The ASACUSA collaboration aims to measure the ground state hyperfine splitting (GS-HFS) of antihydrogen, the antimatter counterpart to atomic hydrogen. Comparisons of the corresponding transitions in those two systems will provide sensitive tests of the CPT symmetry, the combination of the three discrete symmetries charge conjugation, parity, and time reversal. For offline tests of the GS-HFS spectroscopy apparatus we constructed a source of cold polarised atomic hydrogen. In these proceedings we report the successful observation of the hyperfine structure transitions of atomic hydrogen with our apparatus in the earth’s magnetic field.

  4. Atomic transport by ion beam mixing in the radiation enhanced diffusion region

    International Nuclear Information System (INIS)

    In order to study atomic transport in the radiation enhanced diffusion (RED) region, Pd/Co bilayers were intermixed by 80keV Ar+ in the temperature range from 90 K to 700 K. The critical temperature for the onset of RED was found to be ∼400 K, and the transported amount of Pd atoms was found to be always larger than that of Co in the RED region. This result cannot be explained by pre-existing models. Thus the authors have developed a comprehensive model for atomic transport in the RED region including size effect, damage controlled effect, and cohesive energy effect

  5. Effect of Pt:Sn atomic ratio on the preparation of PtSn/C electrocatalysts using electron beam irradiation

    International Nuclear Information System (INIS)

    PtSn/C electrocatalysts were prepared with Pt:Sn atomic ratios of 3:1, 1:1 and 1:3 in water/2-propanol using electron beam irradiation. The obtained materials were characterized by EDX, XRD and cyclic voltammetry. The ethanol electro-oxidation was studied by chronoamperometry. The XRD diffractograms of the PtSn/C electrocatalysts showed typical face-centered cubic (fcc) structure of platinum and the presence of a SnO2 phase (cassiterite). The mean crystallite sizes of Pt fcc phase was in the range of 3.0-3.5 nm. The PtSn/C electrocatalysts were active for ethanol electro-oxidation at room temperature and the material prepared with Pt:Sn atomic ratio of 1:1 showed the best activity. (author)

  6. Energy band alignment of atomic layer deposited HfO2 on epitaxial (110)Ge grown by molecular beam epitaxy

    OpenAIRE

    Hudait, Mantu K.; Zhu, Y.; Maurya, Deepam; Priya, Shashank

    2013-01-01

    The band alignment properties of atomic layer HfO2 film deposited on epitaxial (110)Ge, grown by molecular beam epitaxy, was investigated using x-ray photoelectron spectroscopy. The cross-sectional transmission electron microscopy exhibited a sharp interface between the (110)Ge epilayer and the HfO2 film. The measured valence band offset value of HfO2 relative to (110)Ge was 2.28 +/- 0.05 eV. The extracted conduction band offset value was 2.66 +/- 0.1 eV using the bandgaps of HfO2 of 5.61 eV ...

  7. Stern Gerlach interferometry with metastable argon atoms: an immaterial mask modulating the profile of a supersonic beam

    CERN Document Server

    Viaris De Lesegno, B; Perales, F; Mainos, C; Reinhardt, J; Baudon, J; Grancharova, D; Durt, T; Robert, J; Boustimi, M; Bocvarski, V; Dos Santos, F P; Durt, T; Haberland, H

    2003-01-01

    A new Stern Gerlach interferometer operating with a nozzle beam of metastable argon atoms Ar* (3p sup 5 4s, sup 3 P sub 2) is described. The selection of incoming (polarisation) and outgoing (analysis) Zeeman sublevels is achieved by use of laser induced transitions at two wavelengths, 811.5 nm (closed J 2 -> J = 3 transition) and 801.5 nm (open J = 2 -> J = 2 transition). Linear superpositions of Zeeman sublevels, just beyond the polarizer and just before the analyser, are prepared by means of two zones where Majorana transitions take place. In between, a controlled magnetic field configuration (the phase object) is produced within a triple mu-metal shielding. Standard interference patterns are obtained by scanning the field and detecting the atoms by secondary electron emission from a Faraday cup. When a static radial magnetic gradient is used, the beam profile is modulated by interference. The transverse pattern. which can be translated at will by adding a homogeneous field, is observed for the first time ...

  8. Stern Gerlach interferometry with metastable argon atoms: an immaterial mask modulating the profile of a supersonic beam

    Energy Technology Data Exchange (ETDEWEB)

    Viaris de Lesegno, B. [Toulouse-3 Univ., LCAR-IRSAMC, 31 (France); Karam, J.C.; Perales, F.; Mainos, C.; Reinhardt, J.; Baudon, J.; Grancharova, D.; Durt, T.; Robert, J. [Paris-13 Univ., Lab. de Physique des Lasers, 93 - Villetaneuse (France); Boustimi, M. [ENSSAT, Lab. d' Optronique, 22 - Lannion (France); Bocvarski, V. [Institute of Physics, Zumun (Yugoslavia); Dos Santos, F.P. [Laboratoire Kastler-Brossel, 75 - Paris (France); Durt, T. [Brussel Vrije Universiteit, Tena-Tona, Brussel (Belgium); Haberland, H. [Freiburg Univ. (Germany)

    2003-04-01

    A new Stern Gerlach interferometer operating with a nozzle beam of metastable argon atoms Ar* (3p{sup 5} 4s, {sup 3}P{sub 2}) is described. The selection of incoming (polarisation) and outgoing (analysis) Zeeman sublevels is achieved by use of laser induced transitions at two wavelengths, 811.5 nm (closed J 2 {yields} J = 3 transition) and 801.5 nm (open J = 2 {yields} J = 2 transition). Linear superpositions of Zeeman sublevels, just beyond the polarizer and just before the analyser, are prepared by means of two zones where Majorana transitions take place. In between, a controlled magnetic field configuration (the phase object) is produced within a triple {mu}-metal shielding. Standard interference patterns are obtained by scanning the field and detecting the atoms by secondary electron emission from a Faraday cup. When a static radial magnetic gradient is used, the beam profile is modulated by interference. The transverse pattern. which can be translated at will by adding a homogeneous field, is observed for the first time using a multi-channel electron multiplier followed by a phosphor screen and a CCD camera. The results satisfactorily agree with all theoretical predictions. (authors)

  9. Stern Gerlach interferometry with metastable argon atoms: an immaterial mask modulating the profile of a supersonic beam

    International Nuclear Information System (INIS)

    A new Stern Gerlach interferometer operating with a nozzle beam of metastable argon atoms Ar* (3p5 4s, 3P2) is described. The selection of incoming (polarisation) and outgoing (analysis) Zeeman sublevels is achieved by use of laser induced transitions at two wavelengths, 811.5 nm (closed J 2 → J = 3 transition) and 801.5 nm (open J = 2 → J = 2 transition). Linear superpositions of Zeeman sublevels, just beyond the polarizer and just before the analyser, are prepared by means of two zones where Majorana transitions take place. In between, a controlled magnetic field configuration (the phase object) is produced within a triple μ-metal shielding. Standard interference patterns are obtained by scanning the field and detecting the atoms by secondary electron emission from a Faraday cup. When a static radial magnetic gradient is used, the beam profile is modulated by interference. The transverse pattern. which can be translated at will by adding a homogeneous field, is observed for the first time using a multi-channel electron multiplier followed by a phosphor screen and a CCD camera. The results satisfactorily agree with all theoretical predictions. (authors)

  10. Stern Gerlach interferometry with metastable argon atoms: an immaterial mask modulating the profile of a supersonic beam

    Science.gov (United States)

    Viaris de Lesegno, B.; Karam, J. C.; Boustimi, M.; Perales, F.; Mainos, C.; Reinhardt, J.; Baudon, J.; Bocvarski, V.; Grancharova, D.; Pereira Dos Santos, F.; Durt, T.; Haberland, H.; Robert, J.

    2003-04-01

    A new Stern Gerlach interferometer operating with a nozzle beam of metastable argon atoms Ar* (3p5 4s, 3P2) is described. The selection of incoming (polarisation) and outgoing (analysis) Zeeman sublevels is achieved by use of laser induced transitions at two wavelengths, 811.5 nm (closed J = 2 --> J = 3 transition) and 801.5 nm (open J = 2 --> J = 2 transition). Linear superpositions of Zeeman sublevels, just beyond the polariser and just before the analyser, are prepared by means of two zones where Majorana transitions take place. In between, a controlled magnetic field configuration (the phase object) is produced within a triple μ-metal shielding. Standard interference patterns are obtained by scanning the field and detecting the atoms by secondary electron emission from a Faraday cup. When a static radial magnetic gradient is used, the beam profile is modulated by interference. The transverse pattern, which can be translated at will by adding a homogeneous field, is observed for the first time using a multi-channel electron multiplier followed by a phosphor screen and a CCD camera. The results satisfactorily agree with all theoretical predictions.

  11. Opto-structural studies of well-dispersed silicon nano-crystals grown by atom beam sputtering.

    Science.gov (United States)

    Saxena, Nupur; Kumar, Pragati; Kabiraj, Debulal; Kanjilal, Dinakar

    2012-01-01

    Synthesis and characterization of nano-crystalline silicon grown by atom beam sputtering technique are reported. Rapid thermal annealing of the deposited films is carried out in Ar + 5% H2 atmosphere for 5 min at different temperatures for precipitation of silicon nano-crystals. The samples are characterized for their optical and structural properties using various techniques. Structural studies are carried out by micro-Raman spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy, and selected area electron diffraction. The optical properties are studied by photoluminescence and UV-vis absorption spectroscopy, and bandgaps are evaluated. The bandgaps are found to decrease after rapid thermal treatment. The micro-Raman studies show the formation of nano-crystalline silicon in as-deposited as well as annealed films. The shifting and broadening in Raman peak suggest formation of nano-phase in the samples. Results of micro-Raman, photoluminescence, and TEM studies suggest the presence of a bimodal crystallite size distribution for the films annealed at higher temperatures. The results show that atom beam sputtering is a suitable technique to synthesize nearly mono-dispersed silicon nano-crystals. The size of the nano-crystals may be controlled by varying annealing parameters. PMID:23031449

  12. Generation of Attosecond X-ray Pulses Beyond the Atomic Unit of Time Using Laser Induced Microbunching in Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, D.; Huang, Z.; Stupakov, G.; /SLAC

    2009-12-11

    Ever since the discovery of mode-locking, efforts have been devoted to reducing the duration of laser pulses since the ultrashort pulses are critical to explore the dynamics occurred on a ever-shorter timescale. In this paper we describe a scheme that's capable of generating intense attosecond x-ray pulses with duration beyond the atomic unit of time ({approx}24 attoseconds). The scheme combines the echo-enabled harmonic generation technique with the bunch compression which allows one to generate harmonic numbers of a few hundred in a microbunched beam through up-conversion of the frequency of a UV seed laser. A few-cycle intense IR laser is used to generate the required energy chirp in the beam for bunch compression and for selection of an attosecond x-ray pulse. Using a representative realistic set of parameters, we show that 1 nm x-ray pulse with peak power of a few hundred MW and duration as short as 20 attoseconds (FWHM) can be generated from a 200 nm UV seed laser. The proposed scheme may enable the study of electronic dynamics with a resolution beyond the atomic unit of time and may open a new regime of ultrafast sciences.

  13. Beam experiments with state selected Ne (3P0, 3P2) metastable atoms

    International Nuclear Information System (INIS)

    Metastable rare gas atoms play an important role in all types of plasmas and gas discharges, e.g. in fluorescent lamps and in laser discharges (helium-neon laser or excimer lasers). In this thesis, the metastable states of NeI are studied. First, the theory of excited neon atoms and diatomic molecules is introduced, as well as Penning ionisation. Next, some experimental facilities are described (e.g. the dye laser system). With these instruments, natural lifetime measurements of the 2p fine structure states of NeI are carried out. Results are reported. Finally, total Penning ionisation cross sections are calculated using the optical potential model. (Auth.)

  14. Nuclear moments and isotopic variation of the mean square charge radii of strontium nuclei by atomic beam laser spectroscopy

    International Nuclear Information System (INIS)

    Hyperfine structure and optical isotope shift measurements have been performed on a series of stable and radioactive strontium isotopes (A = 80 to 90), including two isomers 85m and 87m. The spectroscopy applied continuous wave dye laser induced fluorescence of free atoms at λ=293.2 nm in a well collimated atomic beam. The 293.2 nm ultraviolet light was generated by frequency doubling the output of a dye laser in either a temperature tuned Ammonium Dihydrogen Arsenate (ADA) crystal or an angle tuned Lithium Iodate crystal. A special radio frequency (rf) technique was used to tune the dye laser frequency with long term stability. Radioactive Sr isotopes were produced either by neutron capture of stable strontium or by (α,xn) reactions from krypton gas. The samples were purified by an electromagnetic mass separator and their sizes were of order 100 pg, which corresponds to 1011 atoms. The observed results of the hyperfine structure components are evaluated in terms of nuclear magnetic dipole moments and electric quadrupole moments. Changes in mean square charge radii of strontium nuclei which were extracted from the isotope shift measurements, exhibit a distinct shell effect at the neutron magic number N=50. The experimental data are analysed and compared with some theoretical nuclear model predictions. The strong increase of the nuclear charge radii with decreasing neutron number of isotopes below N=50 is in agreement with the variation of the mean square deformation extracted from measured B(E2) values. (orig.)

  15. Spectroscopic study of atomic beams generated by laser ablation of multi-layer targets

    International Nuclear Information System (INIS)

    An experiment is described where Li- and Al-beams were generated by ablation of thin, multi-layer targets using a Q-Switched ruby laser with a total energy density up to 30 Jcm-2. Measurements using laser induced fluorescence and mass spectroscopy were combined to analyse the energy- and density distribution and the temporal structure of the beams. The maximum energy turned out to be several eV for Li and several 10 eV for Al with a peak density in the range of 1010 cm-3 for both Li and Al. The targets were analysed by optical microscopy and secondary ion mass spectroscopy providing information about the size of the spots and the structure of the metal film before and after the ablation experiment. (orig.)

  16. Operation beam switching at the FAKEL accelerator of the Kurchatov's Institute for Atomic Energy

    International Nuclear Information System (INIS)

    The results of operative beam switching system development for the FAKEL accelerator with five electron-optical channels are presented. A single there structure is used in the pulsed magnet. A pulse generator is based on the method of multiplication in a capacitor. The pulse magnet with 3 deg bending angle is arranged at the accelerator axis in front of the magnet with a constant field. The magnetic screen is arranged inside the magnet with a constant field. An electron beam is bended from the accelerator axis, when current pulse is applied to the magnet, and hits the field of the permanent magnet, but during current pulse it hits the magnetic screen. 7 refs.; 2 figs

  17. Electron transfer processes of atomic and molecular doubly charged ions: information from beam experiments

    Czech Academy of Sciences Publication Activity Database

    Herman, Zdeněk

    2013-01-01

    Roč. 111, 12-13 (2013), s. 1697-1710. ISSN 0026-8976 R&D Projects: GA ČR GA203/00/0632; GA AV ČR IAA400400702 Grant ostatní: GA AV ČR(CZ) IAA440410 Institutional support: RVO:61388955 Keywords : doubly charged ions * electron transfer processes * beam experiments Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.642, year: 2013

  18. Production of DT neutrons by means of TiT targets and analyzed atomic deuteron beams

    International Nuclear Information System (INIS)

    The half-lives of TiT targets irradiated with pure d+ beams were investigated at a current density of about 1 mA/cm2. Values of 17 and 13 mAh/cm2 were found for 5 and 2 C/sq. inch targets in agreement with previous experiments at lower current densities (0.3 mAh/cm2). (Auth.)

  19. Study of the fast neutral atom beam injection on TFR tokamak

    International Nuclear Information System (INIS)

    During neutral beam injection experiments on TFR, the increase of the plasma temperature appears to be weak and is saturating at high power. This observation leads to question the classical scheme of power coupling to the thermal plasma and to check experimentally its successive steps. First of all, the neutral beam transmission and capture in the plasma, measured by calorimetric methods, are in agreement with the classical calculations. Next the confinement and thermalization of the fast ions is reviewed by means of three different measurements: charge exchange analysis of fast neutrals leaving the plasma (an auxiliary modulated neutral beam gives a spatially resolved measurement); neutron flux analysis during injection of deuterium ions into a deuterium plasma; measurement of the fast ions trapped in the toroidal magnetic field ripples. These experiments show that a non-classical mechanism transports the most energetic ions towards the plasma periphery. This phenomenon then limits the overall power that can be effectively absorbed in the plasma centre and contributes to deteriorate the energy confinement. Finally the respective role of thermal and non-thermal populations in the power balance is addressed

  20. Nondestructive atomic compositional analysis of BeMgZnO quaternary alloys using ion beam analytical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Zolnai, Z., E-mail: zolnai.zsolt@ttk.mta.hu [Research Centre for Natural Sciences, Institute of Technical Physics and Materials Science (MFA), Konkoly-Thege M. út 29-33, H-1121 Budapest (Hungary); Toporkov, M. [Department of Electrical and Computer Engineering, Virginia Commonwealth University, 601W Main St, Richmond, VA 23284 (United States); Volk, J. [Research Centre for Natural Sciences, Institute of Technical Physics and Materials Science (MFA), Konkoly-Thege M. út 29-33, H-1121 Budapest (Hungary); Department of Electrical and Computer Engineering, Virginia Commonwealth University, 601W Main St, Richmond, VA 23284 (United States); Demchenko, D.O. [Department of Physics, Virginia Commonwealth University, 701W. Grace St., Richmond, VA 23284 (United States); Okur, S. [Department of Electrical and Computer Engineering, Virginia Commonwealth University, 601W Main St, Richmond, VA 23284 (United States); Szabó, Z. [Research Centre for Natural Sciences, Institute of Technical Physics and Materials Science (MFA), Konkoly-Thege M. út 29-33, H-1121 Budapest (Hungary); Özgür, Ü.; Morkoç, H.; Avrutin, V. [Department of Electrical and Computer Engineering, Virginia Commonwealth University, 601W Main St, Richmond, VA 23284 (United States); Kótai, E. [Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Konkoly-Thege M. út 29-33, H-1121 Budapest (Hungary)

    2015-02-01

    Highlights: • BeMgZnO thin layers were grown with plasma-assisted molecular beam epitaxy (MBE). • The Be contents were accurately measured with RBS and proton elastic backscattering. • The Tauc bandgap was measured from optical transmittance experiments. • The bandgap has been varied between 3.26 eV and 4.62 eV via the Be and Mg content. • Experimental and density functional theory calculated bandgaps were in good agreement. - Abstract: The atomic composition with less than 1–2 atom% uncertainty was measured in ternary BeZnO and quaternary BeMgZnO alloys using a combination of nondestructive Rutherford backscattering spectrometry with 1 MeV He{sup +} analyzing ion beam and non-Rutherford elastic backscattering experiments with 2.53 MeV energy protons. An enhancement factor of 60 in the cross-section of Be for protons has been achieved to monitor Be atomic concentrations. Usually the quantitative analysis of BeZnO and BeMgZnO systems is challenging due to difficulties with appropriate experimental tools for the detection of the light Be element with satisfactory accuracy. As it is shown, our applied ion beam technique, supported with the detailed simulation of ion stopping, backscattering, and detection processes allows of quantitative depth profiling and compositional analysis of wurtzite BeZnO/ZnO/sapphire and BeMgZnO/ZnO/sapphire layer structures with low uncertainty for both Be and Mg. In addition, the excitonic bandgaps of the layers were deduced from optical transmittance measurements. To augment the measured compositions and bandgaps of BeO and MgO co-alloyed ZnO layers, hybrid density functional bandgap calculations were performed with varying the Be and Mg contents. The theoretical vs. experimental bandgaps show linear correlation in the entire bandgap range studied from 3.26 eV to 4.62 eV. The analytical method employed should help facilitate bandgap engineering for potential applications, such as solar blind UV photodetectors and

  1. Nondestructive atomic compositional analysis of BeMgZnO quaternary alloys using ion beam analytical techniques

    International Nuclear Information System (INIS)

    Highlights: • BeMgZnO thin layers were grown with plasma-assisted molecular beam epitaxy (MBE). • The Be contents were accurately measured with RBS and proton elastic backscattering. • The Tauc bandgap was measured from optical transmittance experiments. • The bandgap has been varied between 3.26 eV and 4.62 eV via the Be and Mg content. • Experimental and density functional theory calculated bandgaps were in good agreement. - Abstract: The atomic composition with less than 1–2 atom% uncertainty was measured in ternary BeZnO and quaternary BeMgZnO alloys using a combination of nondestructive Rutherford backscattering spectrometry with 1 MeV He+ analyzing ion beam and non-Rutherford elastic backscattering experiments with 2.53 MeV energy protons. An enhancement factor of 60 in the cross-section of Be for protons has been achieved to monitor Be atomic concentrations. Usually the quantitative analysis of BeZnO and BeMgZnO systems is challenging due to difficulties with appropriate experimental tools for the detection of the light Be element with satisfactory accuracy. As it is shown, our applied ion beam technique, supported with the detailed simulation of ion stopping, backscattering, and detection processes allows of quantitative depth profiling and compositional analysis of wurtzite BeZnO/ZnO/sapphire and BeMgZnO/ZnO/sapphire layer structures with low uncertainty for both Be and Mg. In addition, the excitonic bandgaps of the layers were deduced from optical transmittance measurements. To augment the measured compositions and bandgaps of BeO and MgO co-alloyed ZnO layers, hybrid density functional bandgap calculations were performed with varying the Be and Mg contents. The theoretical vs. experimental bandgaps show linear correlation in the entire bandgap range studied from 3.26 eV to 4.62 eV. The analytical method employed should help facilitate bandgap engineering for potential applications, such as solar blind UV photodetectors and heterostructures

  2. Chemical reactions of H and D atoms with NO2 and ClNO, a crossed molecular beam study

    International Nuclear Information System (INIS)

    The chemical reactions of H and D atoms with NO2 and ClNO have been studied at a collision energy E = 0.44 eV(42kJ/mol) in a crossed molecular beam experiment. Velocity and angular distributions were measured and are used to construct the center of mass (CM) distributions. The earlier reported isotope effect of the angular distributions for H, D + NO2 is shown to be due to the different CM to LAB conversions. The CM angular distribution is nearly isotropic for H + NO2, but shows strong backward peaking for H + ClNO. The measured translational energy spectra are in agreement with recent fluorescence and chemiluminescence results. The reaction H + NO2 proceeds via a long lived intermediate complex, while H + ClNO is a direct reaction. (orig.)

  3. Pseudopotential calculations of photoionization of atoms in the x-ray photon energy range and FEL beam monitor development

    International Nuclear Information System (INIS)

    A pseudopotential model for calculation of atomic processes under interaction with hard x-ray photons is applied to calculation of Krypton photoionization cross sections by photons with energy in the 20–25 keV range. These cross sections, as well as the mean charge of the resulting ions calculated using the Monte Carlo simulation scheme, are in good agreement with the other theoretical calculations and with the experiment. The obtained results open the doors for new techniques in the design of gas-monitor detectors to control the intensity, coordinates and energy of x-ray free-electron laser (XFEL) beams in the hard x-ray photon energy range. First, Monte Carlo simulations of a scintillation detector application for gas-monitors have been performed. (letter)

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

    Energy Technology Data Exchange (ETDEWEB)

    Schnürer, M.; Abicht, F.; Priebe, G.; Braenzel, J. [Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin (Germany); Prasad, R. [Institute for Laser and Plasma Physics, Heinrich Heine University, Duesseldorf 40225 (Germany); Borghesi, M. [School of Mathematics and Physics, The Queen' s University of Belfast, Belfast BT7 1NN (United Kingdom); ELI–Beamlines, Institute of Physics, Czech Academy of Science, 18221 Prague (Czech Republic); Andreev, A. [Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin (Germany); Vavilov State Optical Institute, 119034 St. Petersburg (Russian Federation); Nickles, P. V. [WCU Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Jequier, S.; Tikhonchuk, V. [Centre Lasers Intenses et Applications, University of Bordeaux, CEA, CNRS, 33405 Talence (France); Ter-Avetisyan, S. [ELI–Beamlines, Institute of Physics, Czech Academy of Science, 18221 Prague (Czech Republic)

    2013-11-15

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

  5. Generation of One-Dimensional Array of Focused Hollow-Beam Pipes and Its Surface Microscopic Waveguide for Cold Atoms or Molecules

    Institute of Scientific and Technical Information of China (English)

    JI Xian-Ming; XIA Yong; YIN Jian-Ping

    2004-01-01

    We propose a new scheme to guide cold atoms (or molecules) by using a one-dimensional (1D) array of focused hollow-beam pipes generated by the combination of a binary phase grating and a 1D array of micro-cylindrical lenses on the substrate surface. We also calculate the intensity distribution of the focused hollow-beam pipe array and its optical potential for 85Rb atoms. The result shows that when the blue detuning of the incident beam and its intensity are 10 GHz and 7.0 × 103 W/m2 respectively, the horizontal dark spot size of each focused hollow-beam pipe and the efficient optical potential are 4.4μm and ~ 0.23mK, which is high enough to guide cold 85Rb atoms (~ 20 μK) from a standard optical molasses and then to realize the 1D array of surface atomic waveguides on an atom chip.

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

    International Nuclear Information System (INIS)

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

  7. Atomic collision experiments utilizing low-velocity, highly-charged ion beams

    International Nuclear Information System (INIS)

    Intense beams of highly-stripped ions are now routinely produced at low velocities using the Brookhaven dual MP-tandems in a unique four-stage accel/decel mode. This mode of operation combines three stages of acceleration, stripping at high energy, and one stage of deceleration to near-zero velocity. To date, experiments have used 10-100 nA beams of bare and few-electron heavy ions at energies as low as 0.2 MeV/amu, and upgrades of the facility should push the lower limit below 0.1 MeV/amu. Recent experiments, such as measurements of charge transfer and x-ray production for S6-16+ on He and Ar at 6-20 MeV and P(b) measurements for MO x-rays produced in Cl16+ + Ar collisions at 20, 10 and 5 MeV have demonstrated the usefulness of highly-stripped, low-velocity projectiles. These experiments and a few possibilities for future experiments are discussed

  8. Beam dynamics of a double-gap acceleration cell for ion implantation with multiple atomic species

    International Nuclear Information System (INIS)

    As a result of our work on ion implantation, we derived equations for the beam dynamics of a two-gap-resonator cavity for accelerating and bunching various ion species of varying energies with the cavity designed for one particular ion species of a given energy (the design-reference particle). A two gap structure is useful at low resonant frequencies where lumped circuit elements (inductors) can be used and the structure kept small. A single gap structure has the advantage that each gap can be independently phased to produce the desired beam dynamics behavior for various ion species and ion energies. However at low frequencies, single gap resonant structures can be large. We find that the two-gap structure, where the phase difference between gaps, for the design reference particle, is fixed at π radians can give acceptable performance provided that the individual two gap cells in the entire accelerator are optimized for the ion species having the largest mass to charge ratio and having the maximum required output energy. Our equations show how to adjust the cavity phases and electric fields to obtain equivalent first-order accelerator performance for various ion species and energies. These equations allow for the effective evaluation of various accelerator concepts and can facilitate the tuning of a linac when changing energies and ion species. Extensive simulations have confirmed the efficacy of our equations. copyright 1997 American Institute of Physics

  9. Atom probe specimen preparation with a dual beam SEM/FIB miller

    International Nuclear Information System (INIS)

    Dual beam scanning electron microscope/focused ion beam (SEM/FIB) methods complement electropolishing methods and enable specimens to be made from a wider range of materials. Several methods have been developed to fabricate specimens from different forms of materials, including thin ribbons, mechanically ground sheet and fine powders. In addition, FIB-based methods can be used in conjunction with electropolishing methods to improve the shape, surface finish and taper angle of specimens. Several lift-out (LO) methods have been developed for selecting specific microstructural features or other regions of interest such as phases, interfaces, grain boundaries, subsurface or implanted regions and interdendritic regions. These LO methods make use of an in situ nanomanipulator and platinum deposition to transfer and attach the lifted out volume to a post for final annular milling into a needle-shaped specimen. In order to improve the efficiency and to facilitate the LO procedure, some special specimen mounts that hold both the specimen and the support post at the appropriate working distance have been developed

  10. Fabrication and characterization of tunnel barriers in a multi-walled carbon nanotube formed by argon atom beam irradiation

    International Nuclear Information System (INIS)

    We have evaluated tunnel barriers formed in multi-walled carbon nanotubes (MWNTs) by an Ar atom beam irradiation method and applied the technique to fabricate coupled double quantum dots. The two-terminal resistance of the individual MWNTs was increased owing to local damage caused by the Ar beam irradiation. The temperature dependence of the current through a single barrier suggested two different contributions to its Arrhenius plot, i.e., formed by direct tunneling through the barrier and by thermal activation over the barrier. The height of the formed barriers was estimated. The fabrication technique was used to produce coupled double quantum dots with serially formed triple barriers on a MWNT. The current measured at 1.5 K as a function of two side-gate voltages resulted in a honeycomb-like charge stability diagram, which confirmed the formation of the double dots. The characteristic parameters of the double quantum dots were calculated, and the feasibility of the technique is discussed

  11. 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

  12. Formation and atomic structure of tetrahedral carbon onion produced by electron-beam irradiation

    International Nuclear Information System (INIS)

    Full text: Various fullerene structures has been designed and produced after the discovery of C60. These fullerene materials are good candidates as nanoscale devises such as single-electron devices, nano-diode, nano-transistor, nano-ball bearing and insulator lubricant. The onion structures, which generally consist of some quasi-spherical fullerene group, are also discovered and studied in detail. The tetrahedral carbon onions had been calculated to be unstable compared to the spherical onions due to the rigidity. The purpose of the present work is to produce new carbon onion by high-energy electron-irradiation on amorphous carbon at 1250 kV, and to investigate atomic structures and stability of the new carbon onion cluster by high-resolution electron microscopy (HREM) and molecular orbital/mechanics calculations. To confirm the structure model from HREM data, HREM image simulation were carried out. The tetrahedral carbon onion was successfully produced by high-energy electron-irradiation. A HREM image of tetrahedral carbon onion would consist of pentagonal and hexagonal rings. The HREM result indicates that new fullerene structures formed into the carbon onion. Molecular mechanics calculations (MM2), semi-empirical molecular orbital calculations (PM3), and density functional theory (DFT) were used to get structure optimization about first and second internal shell. The energy levels and density of states were also calculated by the first principles method (DV-Xα). The smallest tetrahedral onion in the HREM image agreed well with the proposed structure model of C84atC276. Each vertex consists of a hexagonal ring, and three pentagonal rings exist around the vertex along the edge. In summary, the tetrahedral carbon cluster was produced by energy transfer of electron-irradiation, and the new atomic structure model of tetrahedral carbon onion was proposed. The electronic structures were also calculated theoretically. Copyright (2002) Australian Society for Electron

  13. Molecular beams

    International Nuclear Information System (INIS)

    This book is a timeless and rather complete theoretical and experimental treatment of electric and magnetic resonance molecular-beam experiments for studying the radio frequency spectra of atoms and molecules. The theory of interactions of the nucleus with atomic and molecular fields is extensively presented. Measurements of atomic and nuclear magnetic moments, electric multipole moments, and atomic fine and hyperfine structure are detailed. Useful but somewhat outdated chapters on gas kinetics, molecular beam design, and experimental techniques are also included

  14. Plasmonic properties of Ag nanoparticles embedded in GeO2-SiO2 matrix by atom beam sputtering.

    Science.gov (United States)

    Mohapatra, Satyabrata

    2016-02-01

    Nanocomposite thin films containing Ag nanoparticles embedded in the GeO2-SiO2 matrix were synthesized by the atom beam co-sputtering technique. The structural, optical and plasmonic properties and the chemical composition of the nanocomposite thin films were studied by transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy (EDX), UV-visible absorption spectroscopy and X-ray photoelectron spectroscopy (XPS). UV-visible absorption studies on Ag-SiO2 nanocomposites revealed the presence of a strong localized surface plasmon resonance (LSPR) peak characteristic of Ag nanoparticles at 413 nm, which showed a blue shift of 26 nm (413 to 387 nm) along with a significant broadening and drastic decrease in intensity with the incorporation of 16 at% of Ge into the SiO2 matrix. TEM studies on Ag-GeO2-SiO2 nanocomposite thin films confirmed the presence of Ag nanoparticles with an average size of 3.8 nm in addition to their aggregates with an average size of 16.2 nm. Thermal annealing in air resulted in strong enhancement in the intensity of the LSPR peak, which showed a regular red shift of 51 nm (from 387 to 438 nm) with the increase in annealing temperature up to 500 °C. XPS studies showed that annealing in air resulted in oxidation of excess Ge atoms in the nanocomposite into GeO2. Our work demonstrates the possibility of controllably tuning the LSPR of Ag nanoparticles embedded in the GeO2-SiO2 matrix by single-step thermal annealing, which is interesting for optical applications. PMID:26766559

  15. Influence of ion/atom arrival ratio on structure and optical properties of AlN films by ion beam assisted deposition

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Jian-ping [Department of Energy Material and Technology, General Research Institute for Nonferrous Metals, Beijing 100088 (China); School of Engineering and Technology, China University of Geosciences, Beijing 100083 (China); Fu, Zhi-qiang, E-mail: fuzq@cugb.edu.cn [School of Engineering and Technology, China University of Geosciences, Beijing 100083 (China); Liu, Xiao-peng [Department of Energy Material and Technology, General Research Institute for Nonferrous Metals, Beijing 100088 (China); Yue, Wen; Wang, Cheng-biao [School of Engineering and Technology, China University of Geosciences, Beijing 100083 (China)

    2014-10-30

    Highlights: • AlN films were fabricated by dual ion beam sputtering. • Chemical bond status and phase composition of the films were studied by XPS and XRD. • Optical constants were measured by spectroscopic ellipsometry. • Influence of ion/atom arrival ratio on the films was studied. - Abstract: In order to improve the optical properties of AlN films, the influence of the ion/atom arrival ratio on the structure and optical characteristics of AlN films deposited by dual ion beam sputtering was studied by using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, spectroscopic ellipsometry and UV–vis spectroscopy. The films prepared at the ion/atom arrival ratio of 1.4 are amorphous while the crystalline quality is improved with the increase of the ion/atom arrival ratio. The films deposited at the ion/atom arrival ratio of no less than 1.8 have an approximately stoichiometric ratio and mainly consist of aluminum nitride with little aluminum oxynitride, while metallic aluminum component appears in the films deposited at the ion/atom arrival ratio of 1.4. When the ion/atom arrival ratio is not less than 1.8, films are smooth, high transmitting and dense. The films prepared with high ion/atom arrival ratio (≥1.8) display the characteristic of a dielectric. The films deposited at the ion/atom arrival ratio of 1.4 are coarse, opaque and show characteristic of cermet.

  16. Cadmium and lead determination in foods by beam injection flame furnace atomic absorption spectrometry after ultrasound-assisted sample preparation

    International Nuclear Information System (INIS)

    A simple method for cadmium and lead determination in foods by beam injection flame furnace atomic absorption spectrometry (BIFF-AAS) was proposed. Food slurries were prepared by transferring an exact amount of cryogenic-ground homogenized material (50-100 mg) to centrifuge tubes, followed by addition of 5 ml (up to 2.8 mol l-1) nitric acid solution and sonication in an ultrasonic bath during 5-10 min. Thereafter, slurries were diluted with water to 10 ml, centrifuged during 5 min at 5400 rpm and 400 μl aliquot of the supernatant was analyzed by BIFF-AAS. The detection limits based on peak height measurements were 0.03 μg g-1 Cd and 1.6 μg g-1 Pb for 2% (m/v) slurry (200 mg/10 ml). For method validation, the certified reference materials Pig Kidney (BCR 186) and Rice Flour (NIES 10) were used. Quantitative cadmium and lead recoveries were obtained and no statistical differences were found at 95% level by applying the t-test

  17. Fragmentation and plasmid strand breaks in pure and gold-doped DNA irradiated by beams of fast hydrogen atoms

    Science.gov (United States)

    Wyer, J. A.; Butterworth, K. T.; Hirst, D. G.; Latimer, C. J.; Montenegro, E. C.; Shah, M. B.; Currell, F. J.

    2009-08-01

    The results of an investigation into the damage caused to dry plasmid DNA after irradiation by fast (keV) hydrogen atoms are presented. Agarose gel electrophoresis was used to assess single and double strand break yields as a function of dose in dry DNA samples deposited on a mica substrate. Damage levels were observed to increase with beam energy. Strand break yields demonstrated a considerable dependence on sample structure and the method of sample preparation. Additionally, the effect of high-Z nanoparticles on damage levels was investigated by irradiating DNA samples containing controlled amounts of gold nanoparticles. In contrast to previous (photonic) studies, no enhancement of strand break yields was observed with the particles showing a slight radioprotective effect. A model of DNA damage as a function of dose has been constructed in terms of the probability for the creation of single and double strand breaks, per unit ion flux. This model provides quantitative conclusions about the effects of both gold nanoparticles and the different buffers used in performing the assays and, in addition, infers the proportion of multiply damaged fragments.

  18. Approaching Defect-free Amorphous Silicon Nitride by Plasma-assisted Atomic Beam Deposition for High Performance Gate Dielectric.

    Science.gov (United States)

    Tsai, Shu-Ju; Wang, Chiang-Lun; Lee, Hung-Chun; Lin, Chun-Yeh; Chen, Jhih-Wei; Shiu, Hong-Wei; Chang, Lo-Yueh; Hsueh, Han-Ting; Chen, Hung-Ying; Tsai, Jyun-Yu; Lu, Ying-Hsin; Chang, Ting-Chang; Tu, Li-Wei; Teng, Hsisheng; Chen, Yi-Chun; Chen, Chia-Hao; Wu, Chung-Lin

    2016-01-01

    In the past few decades, gate insulators with a high dielectric constant (high-k dielectric) enabling a physically thick but dielectrically thin insulating layer, have been used to replace traditional SiOx insulator and to ensure continuous downscaling of Si-based transistor technology. However, due to the non-silicon derivative natures of the high-k metal oxides, transport properties in these dielectrics are still limited by various structural defects on the hetero-interfaces and inside the dielectrics. Here, we show that another insulating silicon compound, amorphous silicon nitride (a-Si3N4), is a promising candidate of effective electrical insulator for use as a high-k dielectric. We have examined a-Si3N4 deposited using the plasma-assisted atomic beam deposition (PA-ABD) technique in an ultra-high vacuum (UHV) environment and demonstrated the absence of defect-related luminescence; it was also found that the electronic structure across the a-Si3N4/Si heterojunction approaches the intrinsic limit, which exhibits large band gap energy and valence band offset. We demonstrate that charge transport properties in the metal/a-Si3N4/Si (MNS) structures approach defect-free limits with a large breakdown field and a low leakage current. Using PA-ABD, our results suggest a general strategy to markedly improve the performance of gate dielectric using a nearly defect-free insulator. PMID:27325155

  19. Measurements of radiation near an atomic spectral line from the interaction of a 30 GeV electron beam and a long plasma

    International Nuclear Information System (INIS)

    Emissions produced or initiated by a 30 GeV electron beam propagating through a ∼ 1 m long heat pipe oven containing neutral and partially ionized vapor have been measured near atomic spectral lines in a beam-plasma wakefield experiment. The Cerenkov spatial profile has been studied as a function of oven temperature and pressure, observation wavelength, and ionizing laser intensity and delay. The Cerenkov peak angle is affected by the creating of plasma, and estimates of neutral and plasma density have been extracted. Increases in visible background radiation, consistent with increased plasma recombination emissions due to dissipation of wakefields, were simultaneously measured

  20. A novel approach for site-specific atom probe specimen preparation by focused ion beam and transmission electron backscatter diffraction

    International Nuclear Information System (INIS)

    Atom probe tomography (APT) is a suitable technique for chemical analyses with almost atomic resolution. However, the time-consuming site-specific specimen preparation can be improved. Recently, transmission electron backscatter diffraction (t-EBSD) has been established for high resolution crystallographic analyses of thin foils. In this paper we present the first successful application of a combined focused ion beam (FIB)/t-EBSD preparation of site-specific APT specimens using the example of grain boundary segregation in technically pure molybdenum. It will be shown that the preparation of a grain boundary can be substantially accelerated by t-EBSD analyses in-between the annular milling FIB procedure in the same microscope. With this combined method, a grain boundary can easily be recognized and positioned in the first 220 nm of an APT sample much faster than e.g. with complementary investigations in a transmission electron microscope. Even more, the high resolution technique of t-EBSD gives the opportunity to get crystallographic information of the mapped area and, therefore, an analysis of the grain boundary character to support the interpretation of the APT data files. To optimize this newly developed technique for the application on needle-shaped APT specimens, a parameter study on enhanced background correction, acceleration voltage, and tilt angle was carried out. An acceleration voltage of 30 kV at specimen surface tilt angles between −45° and −35° from horizontal plane leads to the best results. Even for molybdenum the observation of crystal orientation data up to about 200 nm specimen thickness is possible. - Highlights: • We developed a new site-specific APT specimen preparation method by FIB and t-EBSD. • A grain boundary was positioned in the first 220 nm of the APT tip by the FIB/t-EBSD method. • Crystallographic information of the mapped area can be quickly obtained. • An acceleration voltage of 30 kV at specimen surface tilt angles

  1. The intra-atomic motion of bound electrons as a possible source of a systematic error in electron beam polarization measurements by means of a Moller polarimeter

    International Nuclear Information System (INIS)

    The role of the motion of electrons bound in target atoms in electron beam polarization measurements by means of a Moeller polarimeter is discussed. It is shown that this effect can result in an essential overestimate of the value being measured, which exceeds considerably the error of the target polarization determination, and therefore, it should be taken into account in the development of polarimeters. Some recommendations are given to eliminate this systematic error. 8 refs.; 1 fig.; 2 tables. (author)

  2. Multidimensional characterisation of biomechanical structures by combining Atomic Force Microscopy and Focused Ion Beam: A study of the rat whisker.

    Science.gov (United States)

    Adineh, Vahid Reza; Liu, Boyin; Rajan, Ramesh; Yan, Wenyi; Fu, Jing

    2015-07-01

    Understanding the heterogeneity of biological structures, particularly at the micro/nano scale can offer insights valuable for multidisciplinary research in tissue engineering and biomimicry designs. Here we propose to combine nanocharacterisation tools, particularly Focused Ion Beam (FIB) and Atomic Force Microscopy (AFM) for three dimensional mapping of mechanical modulus and chemical signatures. The prototype platform is applied to image and investigate the fundamental mechanics of the rat face whiskers, a high-acuity sensor used to gain detailed information about the world. Grazing angle FIB milling was first applied to expose the interior cross section of the rat whisker sample, followed by a "lift-out" method to retrieve and position the target sample for further analyses. AFM force spectroscopy measurements revealed a non-uniform pattern of elastic modulus across the cross section, with a range from 0.8GPa to 13.5GPa. The highest elastic modulus was found at the outer cuticle region of the whisker, and values gradually decreased towards the interior cortex and medulla regions. Elemental mapping with EDS confirmed that the interior of the rat whisker is dominated by C, O, N, S, Cl and K, with a significant change of elemental distribution close to the exterior cuticle region. Based on these data, a novel comprehensive three dimensional (3D) elastic modulus model was constructed, and stress distributions under realistic conditions were investigated with Finite Element Analysis (FEA). The simulations could well account for the passive whisker deflections, with calculated resonant frequency as well as force-deflection for the whiskers being in good agreement with reported experimental data. Limitations and further applications are discussed for the proposed FIB/AFM approach, which holds good promise as a unique platform to gain insights on various heterogeneous biomaterials and biomechanical systems. PMID:25839121

  3. Measurement of the scalar polarizability of the indium $6p_{1/2}$ state using two-step atomic-beam spectroscopy

    CERN Document Server

    Augenbraun, Benjamin L; Rupasinghe, P M; Majumder, P K

    2016-01-01

    We have completed a measurement of the Stark shift within the $^{115}$In $6s_{1/2} \\rightarrow 6p_{1/2}$ excited-state transition using two-step laser spectroscopy in an indium atomic beam. Combining this measurement with recent experimental results we determine the scalar polarizability, $\\alpha_{0}$, of the $6p_{1/2}$ state to be $7683 \\pm43 \\,a_{0}^{3}$ in atomic units, a result which agrees very well with recent theoretical calculations. In this experiment, one laser, stabilized to the $5p_{1/2} \\rightarrow 6s_{1/2}$ 410~nm transition, was directed transversely to the atomic beam, while a second, overlapping laser was scanned across the 1343~nm $6s_{1/2} \\rightarrow 6p_{1/2}$ transition. We utilized two-tone frequency-modulation spectroscopy of the infrared laser beam to measure the second-step absorption in the interaction region, where the optical depth is less than 10$^{-3}$. In the course of our experimental work we also determined the hyperfine splitting within the $6p_{1/2}$ state, improving upon th...

  4. Calculation of the atomic scattering factors of fast electrons at zero angle of incidence of an electron beam and mean inner crystal potentials

    International Nuclear Information System (INIS)

    The atomic scattering factors of fast electrons at zero angle of incidence of an electron beam, fel(0), are calculated for neutral atoms with Z = 1−54, using the mean-square radii of electron-density distributions in atoms and ions, derived on the basis of the Hartree-Fock wave functions. The values of fel(0) have been calculated for the first time for some positive and negative ions. The obtained values of fel(0) were used to determine the mean inner potentials V0 of metallic, covalent, and ionic crystals. The calculated values of V0 are compared with the experimental data in the literature. The values of V0 calculated for III–V and II–VI compounds are reported.

  5. QED-based Optical Bloch Equations without electric dipole approximation: A model for a two-level atom interacting with a monochromatic X-ray laser beam

    CERN Document Server

    Zhang, Wen-Zhuo

    2012-01-01

    We derive a set of optical Bloch equations (OBEs) directly from the minimal-coupling Hamiltonian density of the bound-state quantum electrodynamics (bound-state QED). Such optical Bloch equations are beyond the former widely-used ones due to that there is no electric dipole approximation (EDA) on the minimal-coupling Hamiltonian density of the bound-state QED. Then our optical Bloch equations can describe a two-level atom interacting with a monochromatic light of arbitrary wavelength, which are suitable to study the spectroscopy and the Rabi oscillations of two-level atoms in X-ray laser beams since that the wavelength of X-ray is close to an atom to make the electric dipole approximation (EDA) invalid.

  6. A short pulse (7 μs FWHM) and high repetition rate (dc-5kHz) cantilever piezovalve for pulsed atomic and molecular beams

    International Nuclear Information System (INIS)

    In this paper we report on the design and operation of a novel piezovalve for the production of short pulsed atomic or molecular beams. The high speed valve operates on the principle of a cantilever piezo. The only moving part, besides the cantilever piezo itself, is a very small O-ring that forms the vacuum seal. The valve can operate continuous (dc) and in pulsed mode with the same drive electronics. Pulsed operation has been tested at repetition frequencies up to 5 kHz. The static deflection of the cantilever, as mounted in the valve body, was measured as a function of driving field strength with a confocal microscope. The deflection and high speed dynamical response of the cantilever can be easily changed and optimized for a particular nozzle diameter or repetition rate by a simple adjustment of the free cantilever length. Pulsed molecular beams with a full width at half maximum pulse width as low as 7 μs have been measured at a position 10 cm downstream of the nozzle exit. This represents a gas pulse with a length of only 10 mm making it well matched to for instance experiments using laser beams. Such a short pulse with 6 bar backing pressure behind a 150 μm nozzle releases about 1016 particles/pulse and the beam brightness was estimated to be 4x1022 particles/(s str). The short pulses of the cantilever piezovalve result in a much reduced gas load in the vacuum system. We demonstrate operation of the pulsed valve with skimmer in a single vacuum chamber pumped by a 520 l/s turbomolecular pump maintaining a pressure of 5x10-6 Torr, which is an excellent vacuum to have the strong and cold skimmed molecular beam interact with laser beams only 10 cm downstream of the nozzle to do velocity map slice imaging with a microchannel-plate imaging detector in a single chamber. The piezovalve produces cold and narrow (Δv/v=2%-3%) velocity distributions of molecules seeded in helium or neon at modest backing pressures of only 6 bar. The low gas load of the cantilever

  7. Atomic nitrogen: a parameter study of a micro-scale atmospheric pressure plasma jet by means of molecular beam mass spectrometry

    International Nuclear Information System (INIS)

    Absolute atomic nitrogen densities (N) in the effluent of a micro-scale atmospheric pressure plasma jet (µ-APPJ) operated in He with small admixtures of molecular nitrogen (N2) are measured by means of molecular beam mass spectrometry. Focusing on changes of the external plasma parameters, the dependency of the atomic nitrogen density on the admixture of molecular nitrogen to the plasma, the variation of applied electrode voltage and the variation of distance between the jet nozzle and the sampling orifice of the mass spectrometer are analysed. When varying the N2 admixture, a maximum density of atomic nitrogen of approximately 1.5  ×  1014 cm−3 (∼6 ppm) is reached at about 0.25% N2 admixture. Moreover, the N density increases approximately linearly with the applied voltage. Both results are comparable to atomic oxygen (O) behaviour of the µ-APPJ operated at equal plasma conditions except for admixing molecular O2 instead of nitrogen (Ellerweg et al 2010 New J. Phys. 12 013021). The N density decreases continuously with increasing distance, but the decrease is slower than in the case of O atoms in He/O2 plasma. N atoms with a density of 2.0  ×  1013 cm−3 (∼0.8 ppm) are still detected at 40 mm distance from the jet nozzle in controlled He/N2 atmosphere. The simple fluid simulation of N diffusion does not reproduce the measured densities of N. Nevertheless, a simulation taking into account atomic nitrogen reactions with gas impurities are able to reproduce the measured data, indicating that these reactions are an important loss mechanism of N atoms. The presented results are relevant for the future investigation of interactions of reactive nitrogen species with biological substrates. (paper)

  8. PREFACE: Advanced Science Research Symposium 2009 Positron, Muon and other exotic particle beams for materials and atomic/molecular sciences (ASR2009)

    Science.gov (United States)

    Higemoto, Wataru; Kawasuso, Atsuo

    2010-05-01

    It is our great pleasure to deliver the proceedings of ASR2009, the Advanced Science Research International Symposium 2009. ASR2009 is part of a series of symposia which is hosted by the Japan Atomic Energy Agency, Advanced Science Research Center (JAEA-ASRC), and held every year with different scientific topics. ASR2009 was held at Tokai in Japan from 10-12 November 2009. In total, 102 participants, including 29 overseas scientists, made 44 oral presentations and 64 poster presentations. In ASR2009 we have focused on material and atomic/molecular science research using positrons, muons and other exotic particle beams. The symposium covered all the fields of materials science which use such exotic particle beams. Positrons, muons and other beams have similar and different features. For example, although positrons and muons are both leptons having charge and spin, they give quite different information about materials. A muon mainly detects the local magnetic state of the solid, while a positron detects crystal imperfections and electron momenta in solids. Other exotic particle beams also provide useful information about materials which is not able to be obtained with muons or positrons. Therefore, the complementary use of particle beams, coupled with an understanding of their relative advantages, leads to greater excellence in materials research. This symposium crossed the fields of muon science, positron science, unstable-nuclei science, and other exotic particle-beam science. We therefore believe that ASR2009 became an especially important meeting for finding new science with exotic particle beams. Finally, we would like to extend our appreciation to all the participants, committee members, and support staff for their great efforts to make ASR2009 a fruitful symposium. ASR2009 Chairs Wataru Higemoto and Atsuo Kawasuso Advanced Science Research Center, Japan Atomic Energy Agency Organizing committee Y Hatano, JAEA (Director of ASRC) M Fujinami, Chiba Univ. R H

  9. 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.

  10. Improving surface smoothness and photoluminescence of CdTe(1 1 1)A on Si(1 1 1) substrates grown by molecular beam epitaxy using Mn atoms

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jyh-Shyang, E-mail: jswang@cycu.edu.tw [Department of Physics, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Center for Nano-Technology, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Tsai, Yu-Hsuan; Chen, Chang-Wei; Dai, Zi-Yuan; Tong, Shih-Chang [Department of Physics, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Yang, Chu-Shou [Graduate Institute of Electro-Optical Engineering, Tatung University, Taipei 10452, Taiwan (China); Wu, Chih-Hung [Institute of Nuclear Energy Research, Longtan 32546, Taiwan (China); Yuan, Chi-Tsu; Shen, Ji-Lin [Department of Physics, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Center for Nano-Technology, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China)

    2014-04-01

    Highlights: • CdTe(1 1 1)A epilayers were grown on Si(1 1 1) substrates by molecular beam epitaxy. • We report an enhanced growth using Mn atoms. • The significant improvements in surface quality and optical properties were found. - Abstract: This work demonstrates an improvement of the molecular beam epitaxial growth of CdTe(1 1 1)A epilayer on Si(1 1 1) substrates using Mn atoms. The reflection high-energy electron diffraction patterns show that the involvement of some Mn atoms in the growth of CdTe(1 1 1)A is even more effective than the use of a buffer layer with a smooth surface for forming good CdTe(1 1 1)A epilayers. 10 K Photoluminescence spectra show that the incorporation of only 2% Mn significantly reduced the intensity of defect-related emissions and considerably increased the integral intensity of exciton-related emissions by a large factor of about 400.

  11. Atomic physics

    International Nuclear Information System (INIS)

    Research activities in atomic physics at Lawrence Berkeley Laboratory during 1976 are described. Topics covered include: experiments on stored ions; test for parity violation in neutral weak currents; energy conservation and astrophysics; atomic absorption spectroscopy, atomic and molecular detectors; theoretical studies of quantum electrodynamics and high-z ions; atomic beam magnetic resonance; radiative decay from the 23Po,2 levels of helium-like argon; quenching of the metastable 2S/sub 1/2/ state of hydrogen-like argon in an external electric field; and lifetime of the 23Po level of helium-like krypton

  12. Study of X-Ray and $\\gamma$-Ray Spectra from Antiprotonic Atoms at the Slowly Extracted Antiproton Beam of LEAR

    CERN Multimedia

    2002-01-01

    This experiment will study the X-ray spectra of antiprotonic atoms and the $\\gamma$ spectra of residual nuclei after the antiproton absorption. We intend to begin with measurements on selected isotopically pure targets. Strong interaction effects, the antiproton absorption and the atomic cascade are analysed through the measurement of energies, lineshapes, relative and absolute intensities of all observable lines. The experiments are continued to determine st in resolved fine structure levels and in different isotopes of the same element. Coincidence techniques may be applied. All components of the experimental set-up are already existing from previous experiments and we could begin the measurements with any slowly extracted beam of low energy at LEAR.

  13. Understanding time-resolved processes in atomic-layer etching of ultra-thin Al2O3 film using BCl3 and Ar neutral beam

    International Nuclear Information System (INIS)

    We scrutinize time-resolved processes occurring in atomic-layer etching (ALET) of ultra-thin Al2O3 film using BCl3 gas and Ar neutral beam by employing density functional theory calculations and experimental measurements. BCl3 gas is found to be preferentially chemisorbed on Al2O3(100) in trans form with the surface atoms creating O-B and Al-Cl contacts. We disclose that the most likely sequence of etching events involves dominant detachment of Al-associated moieties at early etching stages in good agreement with our concurrent experiments on tracking Al2O3 surface compositional variations during Ar bombardment. In this etching regime, we find that ALET requires half the maximum reaction energy of conventional plasma etching, which greatly increases if the etching sequence changes.

  14. Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling

    OpenAIRE

    Mayer, Marcel; Keskinbora, Kahraman; Grévent, Corinne; Szeghalmi, Adriana; Knez, Mato; Weigand, Markus; Snigirev, Anatoly; Snigireva, Irina; Schütz, Gisela

    2013-01-01

    Fresnel zone plates (FZPs) recently showed significant improvement by focusing soft X-rays down to ∼10 nm. In contrast to soft X-rays, generally a very high aspect ratio FZP is needed for efficient focusing of hard X-rays. Therefore, FZPs had limited success in the hard X-ray range owing to difficulties of manufacturing high-aspect-ratio zone plates using conventional techniques. Here, employing a method of fabrication based on atomic layer deposition (ALD) and focused ion beam (FIB) milling,...

  15. Optical molasses loaded from a slow atomic beam%应用慢速原子束制备冷原子粘团的研究

    Institute of Scientific and Technical Information of China (English)

    陈江; 张辉; 阮军; 王心亮; 刘丹丹; 张首刚

    2012-01-01

    Preparation of the optical molasses is one of the key steps for developing a fountain clock. The optical molasses is loaded from a slow atomic beam, and the fluorescence collection method is applied to determine the number of atoms in the optical molasses, meanwhile the time-of-flight(TOF) method is used to measure the temperature of the optical molasses. The number of cold atoms in the optical molasses for loading time of 200 ms is determined to be (8.14±0.2)×107, and the temperature of cold atoms is determined to be (10.72±0.69) μK.%冷原子粘团的制备是喷泉钟研制的关键步骤之一。通过慢速原子束加载获得冷原子粘团,应用荧光收集法测量了冷原子粘团的原子数目,采用飞行时间法测量了冷原子粘团温度。冷原子粘团中原子数目在加载时间200ms的情况下为(8.14±0.2)×107,温度为(10.72±0.69)μK。

  16. Comparative measurement of electron density and temperature profiles in low-temperature ECR discharges by a lithium atom beam and Thomson scattering

    International Nuclear Information System (INIS)

    In this paper a method to determine spatially-resolved profiles of the electron temperature T e and density n e in an electron-cyclotron-resonance (ECR) discharge is presented. This technique is based on the observation of line emission from a neutral Li atom beam, which is injected into the plasma and excited by electron collisions. A collisional-radiative model valid for the injected Li atoms is used to predict the emission intensities as function of n e and T e for several lines theoretically. In contrast to the electron temperature regime representative for the edge of tokamak discharges (T e >5 eV), the ECR discharge offers a T e range where selected line intensity ratios strongly depend on the electron temperature. Therefore, a comparison of the measured ratios with the calculated ones yields T e profiles for the first time. The n e measurement is performed as in tokamaks by observing the attenuation of the beam due to ionization in the plasma. We present radial profiles of T e and n e for discharges in argon and xenon under different operating conditions. These results are compared with results obtained by Thomson scattering. Our measurements give evidence for a satisfying agreement between the two methods. (author)

  17. Detection of somatic mutations at the glycophorin A locus in erythrocytes of atomic bomb survivors using a single beam flow sorter

    International Nuclear Information System (INIS)

    A modified method was developed for measuring the frequency of variant erythrocytes at the glycophorin A locus using a single beam cell sorter (SBS). Fluorescein- or phycoerythrin-labeled monoclonal antibodies specific for the M or N glycophorin A alleles were used for the SBS assay. To prevent contamination of nucleated cells in the sorting windows, the nucleated cells in the fixed erythrocyte sample were stained with propidium iodide before flow sorting. Blood samples were obtained from atomic bomb survivors who were heterozygous for the MN blood type, and the frequencies of the hemizygous and homozygous variant of the M or N glycophorin A allele were measured by the SBS. For the three types of variants, hemizygotes for M and N allele (No and Mo) and homozygotes for M allele (MM), the variant frequency measured by the SBS correlated well with that previously determined by a dual beam cell sorter. Variant frequencies of the No, Mo, and MM cell types in atomic bomb survivors determined by SBS measurements were found to increase with radiation dose (DS86, kerma) as well as with the frequency of chromosome aberrations in lymphocytes

  18. Order within disorder: The atomic structure of ion-beam sputtered amorphous tantala (a-Ta2O5)

    Science.gov (United States)

    Bassiri, Riccardo; Liou, Franklin; Abernathy, Matthew R.; Lin, Angie C.; Kim, Namjun; Mehta, Apurva; Shyam, Badri; Byer, Robert L.; Gustafson, Eric K.; Hart, Martin; MacLaren, Ian; Martin, Iain W.; Route, Roger K.; Rowan, Sheila; Stebbins, Jonathan F.; Fejer, Martin M.

    2015-03-01

    Amorphous tantala (a-Ta2O5) is a technologically important material often used in high-performance coatings. Understanding this material at the atomic level provides a way to further improve performance. This work details extended X-ray absorption fine structure measurements of a-Ta2O5 coatings, where high-quality experimental data and theoretical fits have allowed a detailed interpretation of the nearest-neighbor distributions. It was found that the tantalum atom is surrounded by four shells of atoms in sequence; oxygen, tantalum, oxygen, and tantalum. A discussion is also included on how these models can be interpreted within the context of published crystalline Ta2O5 and other a-T2O5 studies.

  19. Order within disorder: The atomic structure of ion-beam sputtered amorphous tantala (a-Ta2O5

    Directory of Open Access Journals (Sweden)

    Riccardo Bassiri

    2015-03-01

    Full Text Available Amorphous tantala (a-Ta2O5 is a technologically important material often used in high-performance coatings. Understanding this material at the atomic level provides a way to further improve performance. This work details extended X-ray absorption fine structure measurements of a-Ta2O5 coatings, where high-quality experimental data and theoretical fits have allowed a detailed interpretation of the nearest-neighbor distributions. It was found that the tantalum atom is surrounded by four shells of atoms in sequence; oxygen, tantalum, oxygen, and tantalum. A discussion is also included on how these models can be interpreted within the context of published crystalline Ta2O5 and other a-T2O5 studies.

  20. Effect of radiation-thermal treatment with focused electron beam on fine atomic structure and carbide formation in roll steel

    International Nuclear Information System (INIS)

    Using nuclear physics methods - positron annihilation and nuclear gamma-resonance vacancy type point defects concentration and distribution changes as well as carbide phase precipitation in steel surface layers were studied. Steel for color deformation rolls was irradiated with focused 1.5 MeV electron beam at 400-550 deg C

  1. Carbon beam extraction with 14.5 GHz electron cyclotron resonance ion source at Korea Atomic Energy Research Institute.

    Science.gov (United States)

    Lee, Cheol Ho; Oh, Byung-Hoon; Chang, Dae-Sik; Jeong, Sun-Chan

    2014-02-01

    A 14.5 GHz Electron Cyclotron Resonance ion source (ECRIS) has been made to produce C(4+) beam for using a carbon therapy facility and recently tested at KAERI. Highly charged carbon ions have been successfully extracted. When using only CO2 gas, the beam current of C(4+) was almost 14 μA at 15 kV extraction voltage. To get higher current of the C(4+) beam, while optimizing confinement magnetic field configuration (e.g., axial strengths at minimum and extraction side), gas-mixing (CO2/He), and biased disk were introduced. When the gas mixing ratio of the CO2/He gas is 1:8 at an operational pressure of 5 × 10(-7) mbar and the disk was biased to -150 V relative to the ion source body, the highest current of the C(4+) beam was achieved to be 50 μA, more than three times higher than previously observed only with CO2 gas. Some details on the operating conditions of the ECRIS were discussed. PMID:24593482

  2. Note: Determination of torsional spring constant of atomic force microscopy cantilevers: Combining normal spring constant and classical beam theory

    DEFF Research Database (Denmark)

    Álvarez-Asencio, R.; Thormann, Esben; Rutland, M.W.

    2013-01-01

    A technique has been developed for the calculation of torsional spring constants for AFM cantilevers based on the combination of the normal spring constant and plate/beam theory. It is easy to apply and allow the determination of torsional constants for stiff cantilevers where the thermal power...

  3. 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.

  4. Innovation and optimization of a method of pump-probe polarimetry with pulsed laser beams in view of a precise measurement of parity violation in atomic cesium

    International Nuclear Information System (INIS)

    While Parity Violation (PV) experiments on highly forbidden transitions have been using detection of fluorescence signals; our experiment uses a pump-probe scheme to detect the PV signal directly on a transmitted probe beam. A pulsed laser beam of linear polarisation ε1 excites the atoms on the 6S-7S cesium transition in a colinear electric field E || k(ex). The probe beam (k(pr) || k(ex)) of linear polarisation ε2 tuned to the transition 7S-6P(3/2) is amplified. The small asymmetry (∼ 10-6) in the gain that depends on the handedness of the tri-hedron (E, ε1, ε2) is the manifestation of the PV effect. This is measured as an E-odd apparent rotation of the plane of polarization of the probe beam; using balanced mode polarimetry. New criteria of selection have been devised, that allow us to distinguish the true PV-signal against fake rotations due to electromagnetic interferences, geometrical effects, polarization imperfections, or stray transverse electric and magnetic fields. These selection criteria exploit the symmetry of the PV-rotation - linear dichroism - and the revolution symmetry of the experiment. Using these criteria it is not only possible to reject fake signals, but also to elucidate the underlying physical mechanisms and to measure the relevant defects of the apparatus. The present signal-to-noise ratio allows embarking in PV measurements to reach the 10% statistical accuracy. A 1% measurement still requires improvements. Two methods have been demonstrated. The first one exploits the amplification of the asymmetry at high gain - one major advantage provided by our detection method based on stimulated emission. The second method uses both a much higher incident intensity and a special dichroic component which magnifies tiny polarization rotations. (author)

  5. Spatial dynamics of laser-induced fluorescence in an intense laser beam: experiment and theory in alkali metal atoms

    CERN Document Server

    Auzinsh, Marcis; Ferber, Ruvin; Gahbauer, Florian; Kalnins, Uldis

    2015-01-01

    We have shown that it is possible to model accurately optical phenomena in intense laser fields by taking into account the intensity distribution over the laser beam. We developed a theoretical model that divided an intense laser beam into concentric regions, each with a Rabi frequency that corresponds to the intensity in that region, and solved a set of coupled optical Bloch equations for the density matrix in each region. Experimentally obtained magneto-optical resonance curves for the $F_g=2\\longrightarrow F_e=1$ transition of the $D_1$ line of $^{87}$Rb agreed very well with the theoretical model up to a laser intensity of around 200 mW/cm$^2$ for a transition whose saturation intensity is around 4.5 mW/cm$^2$. We have studied the spatial dependence of the fluorescence intensity in an intense laser beam experimentally and theoretically. An experiment was conducted whereby a broad, intense pump laser excited the $F_g=4\\longrightarrow F_e=3$ transition of the $D_2$ line of cesium while a weak, narrow probe ...

  6. Production of intense beams of mass-selected water cluster ions and theoretical study of atom-water interactions

    CERN Document Server

    Wang, Z P; Reinhard, P -G; Suraud, E; Bruny, G; Montano, C; Feil, S; Eden, S; Abdoul-Carime, H; Farizon, B; Farizon, M; Ouaskit, S; Maerk, T D

    2009-01-01

    The influences of water molecules surrounding biological molecules during irradiation with heavy particles (atoms,ions) are currently a major subject in radiation science on a molecular level. In order to elucidate the underlying complex reaction mechanisms we have initiated a joint experimental and theoretical investigation with the aim to make direct comparisons between experimental and theoretical results. As a first step, studies of collisions of a water molecule with a neutral projectile (C atom) at high velocities (> 0.1 a.u.), and with a charged projectile (proton) at low velocities (< 0.1 a.u.) have been studied within the microscopic framework. In particular, time-dependent density functional theory (TDDFT) was applied to the valence electrons and coupled non-adiabatically to Molecular dynamics (MD) for ionic cores. Complementary experimental developments have been carried out to study projectile interactions with accelerated (< 10 keV) and mass-selected cluster ions. The first size distributio...

  7. Preconcentration, speciation and determination of ultra trace amounts of mercury by modified octadecyl silica membrane disk/electron beam irradiation and cold vapor atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Mercury (II) and methyl mercury cations at the Sub-ppb level were adsorbed quantitatively from aqueous solution onto an octadecyl-bonded silica membrane disk modified by 2-[(2-mercaptophyenylimino)methyl] phenol (MPMP). The trapped mercury was then eluted with 3 ml ethanol and Hg2+ ion was directly measured by cold vapor atomic absorption spectrometry, utilizing tin (II) chloride. Total mercury (Hgt) was determined after conversion of MeHg+ into Hg2+ ion by electron beam irradiation. A sample volume of 1500 ml resulted in a preconcentration factor of 500 and the precision for a sampling volume of 500 ml at a concentration of 2.5 μg l-1 (n = 7) was 3.1%. The limit of detection of the proposed method is 3.8 ng l-1. The method was successfully applied to analysis of water samples, and the accuracy was assessed via recovery experiment

  8. Atomic Oxygen (ATOX) simulation of Teflon FEP and Kapton H surfaces using a high intensity, low energy, mass selected, ion beam facility

    Science.gov (United States)

    Vered, R.; Grossman, E.; Lempert, G. D.; Lifshitz, Y.

    1994-01-01

    A high intensity (greater than 10(exp 15) ions/sq cm) low energy (down to 5 eV) mass selected ion beam (MSIB) facility was used to study the effects of ATOX on two polymers commonly used for space applications (Kapton H and Teflon FEP). The polymers were exposed to O(+) and Ne(+) fluences on 10(exp 15) - 10(exp 19) ions/sq cm, using 30eV ions. A variety of analytical methods were used to analyze the eroded surfaces including: (1) atomic force microscopy (AFM) for morphology measurements; (2) total mass loss measurements using a microbalance; (3) surface chemical composition using x-ray photoelectron spectroscopy (XPS), and (4) residual gas analysis (RGA) of the released gases during bombardment. The relative significance of the collisional and chemical degradation processes was evaluated by comparing the effects of Ne(+) and O(+) bombardment. For 30 eV ions it was found that the Kapton is eroded via chemical mechanisms while Teflon FEP is eroded via collisional mechanisms. AFM analysis was found very powerful in revealing the evolution of the damage from its initial atomic scale (roughness of approx. 1 nm) to its final microscopic scale (roughness greater than 1 micron). Both the surface morphology and the average roughness of the bombarded surfaces (averaged over 1 micron x 1 micron images by the system's computer) were determined for each sample. For 30 eV a non linear increase of the Kapton roughness with the O(+) fluence was discovered (a slow increase rate for fluences phi less than 5 x 10(exp 17) O(+)/sq cm, and a rapid increase rate for phi greater than 5 x 10(exp 17) O(+)/sq cm). Comparative studies on the same materials exposed to RF and DC oxygen plasmas indicate that the specific details of the erosion depend on the simulation facility emphasizing the advantages of the ion beam facility.

  9. Atomic and Nuclear Analytical Methods XRF, Mössbauer, XPS, NAA and Ion-Beam Spectroscopic Techniques

    CERN Document Server

    Verma, H R

    2007-01-01

    This book is a blend of analytical methods based on the phenomenon of atomic and nuclear physics. It comprises comprehensive presentations about X-ray Fluorescence (XRF), Mössbauer Spectroscopy (MS), X-ray Photoelectron Spectroscopy (XPS), Neutron- Activation Analysis (NAA), Particle Induced X-ray Emission Analysis (PIXE), Rutherford Backscattering Analysis (RBS), Elastic Recoil Detection (ERD), Nuclear Reaction Analysis (NRA), Particle Induced Gamma-ray Emission Analysis (PIGE), and Accelerator Mass Spectrometry (AMS). These techniques are commonly applied in the fields of medicine, biology, environmental studies, archaeology or geology et al. and pursued in major international research laboratories.

  10. Coherent Atom Optics With Fast Metastable Beams: Metastable Helium Diffraction By 1D and 2D Magnetized Reflection Gratings

    Science.gov (United States)

    Grucker, J.; Baudon, J.; Karam, J.-C.; Perales, F.; Bocvarski, V.; Ducloy, M.

    2007-04-01

    1D and 2D reflection gratings (Permalloy stripes or dots deposited on silicon), immersed in an external homogeneous static magnetic field, are used to study 1D and 2D diffraction of fast metastable helium atoms He* (23S1). Both the grazing incidence used here and the repulsive potential (for sub-level m = -1) generated by the magnetisation reduce the quenching effect. This periodically structured potential is responsible for the diffraction in the incidence plane as well as for the diffraction in the perpendicular plane.

  11. Non-adiabatic dynamics of reactions of O(1D) with Xe, CO, NO2, and CO2 from crossed atomic and molecular beam experiments

    Science.gov (United States)

    Boering, Kristie

    2015-03-01

    Reactions of the first excited state of atomic oxygen, O(1D), with small molecules such as CO, NO2, and CO2 continue to be of interest in aeronomy and atmospheric chemistry, thus providing additional motivation to understand the dynamics of these reactions and how well they are predicted by theory. In collaboration with Prof. Jim Lin of the Institute of Atomic and Molecular Sciences, Academia Sinica, Taiwan, we have studied the dynamics of quenching and non-quenching reactions between O(1D) and various small molecules using a universal crossed atomic and molecular beam apparatus. New experimental results for the dynamics of quenching of O(1D) by Xe and CO will be presented and compared with previous results for NO2 (K.A. Mar, A.L. Van Wyngarden, C.-W. Liang, Y.T. Lee, J.J. Lin, K.A. Boering, J. Chem. Phys., 137, 044302, doi: 10.1063/1.4736567, 2012) and CO2 (M.J. Perri, A.L. Van Wyngarden, K.A. Boering, J.J. Lin, and Y.T. Lee, J. Chem. Phys., 119(16), 8213-8216, 2003; M.J. Perri, A.L. Van Wyngarden, J.J. Lin, Y.T. Lee, and K.A. Boering, J. Phys. Chem. A, 108(39), 7995-8001, doi: 10.1021/jp0485845, 2004). Among the most intriguing of the new results are for quenching of O(1D) by Xe, for which marked oscillations in the differential cross sections were observed for the O(3P) and Xe products. The shape and relative phase of the oscillatory structure depended strongly on collision energy. This behavior is likely due to the quantum nature of the collision dynamics, caused by interferences among multiple curve crossing pathways accessible during electronic quenching, known as Stueckelberg oscillations.

  12. Analysis of beam interference reflected from atomic force microscope tip and periodic silicon surface under various humidity conditions

    Science.gov (United States)

    Banerjee, Hans P.; Weerasinghe, Asanka T.; Lyuksyutov, Sergei F.

    2012-10-01

    Dynamical sensing based on combination of classical optical effects and atomic force microscopy (AFM) presents challenge for analysis of the forces at the nanoscale and beyond. An interference effect between light reflected from an AFM cantilever and highly reflective silicon surface of the calibration grating was studied for relative humidity (RH) varied between 9 and 60%. Force-distance analysis indicates on separation of capillary, van der Waals, adhesion, and electrostatic forces. The measurements performed in contact AFM mode suggest that the period of interference pattern observed in displacement curves is a function of humidity and varies between 293 nm at RH = 9% and 335 nm at RH > 50% with standard deviation less than 8 nm. Clear change of the interference period suggests that other than hardwarerelated factors may be involved in the formation of the interference in force-distance curves.

  13. The stereo-dynamics of collisional autoionization of ammonia by helium and neon metastable excited atoms through molecular beam experiments

    Energy Technology Data Exchange (ETDEWEB)

    Falcinelli, Stefano, E-mail: stefano.falcinelli@unipg.it; Vecchiocattivi, Franco [Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125 Perugia (Italy); Bartocci, Alessio; Cavalli, Simonetta; Pirani, Fernando [Department of Chemistry, Biology, and Biotechnology, University of Perugia, Via Elce di sotto 8, 06123 Perugia (Italy)

    2015-10-28

    A combined analysis of both new (energy spectra of emitted electrons) and previously published (ionization cross sections) experimental data, measured under the same conditions and concerning electronically excited lighter noble gas –NH{sub 3} collisional autoionization processes, is carried out. Such an analysis, performed by exploiting a formulation of the full potential energy surface both in the real and imaginary parts, provides direct information on energetics, structure, and lifetime of the intermediate collision complex over all the configuration space. The marked anisotropy in the attraction of the real part, driving the approach of reagents, and the selective role of the imaginary component, associated to the charge transfer coupling between entrance and exit channels, suggests that reactive events occur almost exclusively in the molecular hemisphere containing the nitrogen lone pair. Crucial details on the stereo-dynamics of elementary collisional autoionization processes are then obtained, in which the open shell nature of the disclosed ionic core of metastable atom plays a crucial role. The same analysis also suggests that the strength of the attraction and the anisotropy of the interaction increases regularly along the series Ne{sup *}({sup 3}P), He{sup *}({sup 3}S), He{sup *}({sup 1}S)–NH{sub 3}. These findings can be ascribed to the strong rise of the metastable atom electronic polarizability (deformability) along the series. The obtained results can stimulate state of the art ab initio calculations focused on specific features of the transition state (energetics, structure, lifetime, etc.) which can be crucial for a further improvement of the adopted treatment and to better understand the nature of the leading interaction components which are the same responsible for the formation of the intermolecular halogen and hydrogen bond.

  14. High flux source of cold rubidium atoms

    International Nuclear Information System (INIS)

    We report on the production of a continuous, slow, and cold beam of 87Rb atoms with an extremely high flux of 3.2x1012 atoms/s, a transverse temperature of 3 mK, and a longitudinal temperature of 90 mK. We describe the apparatus created to generate the atom beam. Hot atoms are emitted from a rubidium candlestick atomic beam source and transversely cooled and collimated by a 20 cm long atomic collimator section, boosting overall beam flux by a factor of 50. The Rb atomic beam is then decelerated and longitudinally cooled by a 1 m long Zeeman slower

  15. High flux source of cold rubidium atoms

    Science.gov (United States)

    Slowe, Christopher; Vernac, Laurent; Hau, Lene Vestergaard

    2005-10-01

    We report on the production of a continuous, slow, and cold beam of Rb87 atoms with an extremely high flux of 3.2×1012atoms/s, a transverse temperature of 3mK, and a longitudinal temperature of 90mK. We describe the apparatus created to generate the atom beam. Hot atoms are emitted from a rubidium candlestick atomic beam source and transversely cooled and collimated by a 20cm long atomic collimator section, boosting overall beam flux by a factor of 50. The Rb atomic beam is then decelerated and longitudinally cooled by a 1m long Zeeman slower.

  16. Basic features of the generation and diagnostic of atomic hydrogen beams in the ground and metastable 22S /sub 1/2-/ states to determine the fundamental physical constants

    International Nuclear Information System (INIS)

    Although the quantum theory enables one to calculate in principle many physical characteristics and a number of fine effects for elementary particles it can do so only for such elementary atomic systems as hydrogen and hydrogen-like atoms. Therefore, the author used the method and modified beam equipment which makes it possible to study the appropriate beams of atoms in the ground and metastable states at the required metrology level. The metastable state of the hydrogen atoms (MHA) flux was controlled by a special system operating in the particle counting mode with the use of a channel electron multiplier. The principal characteristics of the MHA source are shown. That is, the signal Ng produced by MHA at the monitoing system output as a function of the current. It is noted that in the experiments related to double photoexcitation of MHA in a beam the need to increase the hydrogen beam density in the s2S/sub 1/2/ state is most significant due to a low excitation probability and difficulties met with setting up an adequate power exciting field

  17. Free radical hydrogen atom abstraction from saturated hydrocarbons: A crossed-molecular-beams study of the reaction Cl + C{sub 3}H{sub 8} {yields} HCl + C{sub 3}H{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Blank, D.A.; Hemmi, N.; Suits, A.G.; Lee, Y.T. [Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    The abstraction of hydrogen atoms from saturated hydrocarbons are reactions of fundamental importance in combustion as well as often being the rate limiting step in free radical substitution reactions. The authors have begun studying these reactions under single collision conditions using the crossed molecular beam technique on beamline 9.0.2.1, utilizing VUV undulator radiation to selectively ionize the scattered hydrocarbon free radical products (C{sub x}H{sub 2x+1}). The crossed molecular beam technique involves two reactant molecular beams fixed at 90{degrees}. The molecular beam sources are rotatable in the plane defined by the two beams. The scattered neutral products travel 12.0 cm where they are photoionized using the VUV undulator radiation, mass selected, and counted as a function of time. In the authors initial investigations they are using halogen atoms as protypical free radicals to abstract hydrogen atoms from small alkanes. Their first study has been looking at the reaction of Cl + propane {r_arrow} HCl + propyl radical. In their preliminary efforts the authors have measured the laboratory scattering angular distribution and time of flight spectra for the propyl radical products at collision energies of 9.6 kcal/mol and 14.9 kcal/mol.

  18. Change in magnetic and structural properties of FeRh thin films by gold cluster ion beam irradiation with the energy of 1.67 MeV/atom

    International Nuclear Information System (INIS)

    The effect of energetic cluster ion beam irradiation on magnetic and structural properties of FeRh thin films have been investigated. The cluster ions used in the present studies consist of a few gold atoms with the energy of 1.67 MeV/gold atom. Saturation magnetization of the sample irradiated with Au3 cluster ion beam (280 emu/cc) is larger than that for the irradiated sample with Au1 ion beam (240 emu/cc) for the same irradiation ion fluence. These results can also be confirmed by the X-ray magnetic circular dichroism (XMCD) measurement; the XMCD signal for Au3 cluster ion irradiation is larger than that for Au1 ion irradiation. Since the ion beam irradiation induced magnetization of FeRh is significantly correlated with the amount of the lattice defects in the samples, cluster ion beam irradiation can be considered to effectively introduce the lattice defects in B2-type FeRh rather than the single ion beam. Consequently, cluster ion irradiation is better than single ion irradiation for the viewpoint of saturation magnetization, even if the same irradiation energy is deposited in the samples

  19. Change in magnetic and structural properties of FeRh thin films by gold cluster ion beam irradiation with the energy of 1.67 MeV/atom

    Science.gov (United States)

    Koide, T.; Saitoh, Y.; Sakamaki, M.; Amemiya, K.; Iwase, A.; Matsui, T.

    2014-05-01

    The effect of energetic cluster ion beam irradiation on magnetic and structural properties of FeRh thin films have been investigated. The cluster ions used in the present studies consist of a few gold atoms with the energy of 1.67 MeV/gold atom. Saturation magnetization of the sample irradiated with Au3 cluster ion beam (280 emu/cc) is larger than that for the irradiated sample with Au1 ion beam (240 emu/cc) for the same irradiation ion fluence. These results can also be confirmed by the X-ray magnetic circular dichroism (XMCD) measurement; the XMCD signal for Au3 cluster ion irradiation is larger than that for Au1 ion irradiation. Since the ion beam irradiation induced magnetization of FeRh is significantly correlated with the amount of the lattice defects in the samples, cluster ion beam irradiation can be considered to effectively introduce the lattice defects in B2-type FeRh rather than the single ion beam. Consequently, cluster ion irradiation is better than single ion irradiation for the viewpoint of saturation magnetization, even if the same irradiation energy is deposited in the samples.

  20. Change in magnetic and structural properties of FeRh thin films by gold cluster ion beam irradiation with the energy of 1.67 MeV/atom

    Energy Technology Data Exchange (ETDEWEB)

    Koide, T.; Iwase, A. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Saitoh, Y. [Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Sakamaki, M.; Amemiya, K. [High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 (Japan); Matsui, T., E-mail: t-matsui@21c.osakafu-u.ac.jp [Research Organization for the 21st Century, Osaka Prefecture University Sakai, Osaka 599-8531 (Japan)

    2014-05-07

    The effect of energetic cluster ion beam irradiation on magnetic and structural properties of FeRh thin films have been investigated. The cluster ions used in the present studies consist of a few gold atoms with the energy of 1.67 MeV/gold atom. Saturation magnetization of the sample irradiated with Au3 cluster ion beam (280 emu/cc) is larger than that for the irradiated sample with Au1 ion beam (240 emu/cc) for the same irradiation ion fluence. These results can also be confirmed by the X-ray magnetic circular dichroism (XMCD) measurement; the XMCD signal for Au3 cluster ion irradiation is larger than that for Au1 ion irradiation. Since the ion beam irradiation induced magnetization of FeRh is significantly correlated with the amount of the lattice defects in the samples, cluster ion beam irradiation can be considered to effectively introduce the lattice defects in B2-type FeRh rather than the single ion beam. Consequently, cluster ion irradiation is better than single ion irradiation for the viewpoint of saturation magnetization, even if the same irradiation energy is deposited in the samples.

  1. Atomic Layer Epitaxy of h-BN(0001) Multilayers on Co(0001) and Molecular Beam Epitaxy Growth of Graphene on h-BN(0001)/Co(0001).

    Science.gov (United States)

    Driver, M Sky; Beatty, John D; Olanipekun, Opeyemi; Reid, Kimberly; Rath, Ashutosh; Voyles, Paul M; Kelber, Jeffry A

    2016-03-22

    The direct growth of hexagonal boron nitride (h-BN) by industrially scalable methods is of broad interest for spintronic and nanoelectronic device applications. Such applications often require atomically precise control of film thickness and azimuthal registry between layers and substrate. We report the formation, by atomic layer epitaxy (ALE), of multilayer h-BN(0001) films (up to 7 monolayers) on Co(0001). The ALE process employs BCl3/NH3 cycles at 600 K substrate temperature. X-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED) data show that this process yields an increase in h-BN average film thickness linearly proportional to the number of BCl3/NH3 cycles, with BN layers in azimuthal registry with each other and with the Co(0001) substrate. LEED diffraction spot profile data indicate an average BN domain size of at least 1900 Å. Optical microscopy data indicate the presence of some domains as large as ∼20 μm. Transmission electron microscopy (TEM) and ambient exposure studies demonstrate macroscopic and microscopic continuity of the h-BN film, with the h-BN film highly conformal to the Co substrate. Photoemission data show that the h-BN(0001) film is p-type, with band bending near the Co/h-BN interface. Growth of graphene by molecular beam epitaxy (MBE) is observed on the surface of multilayer h-BN(0001) at temperatures of 800 K. LEED data indicate azimuthal graphene alignment with the h-BN and Co(0001) lattices, with domain size similar to BN. The evidence of multilayer BN and graphene azimuthal alignment with the lattice of the Co(0001) substrate demonstrates that this procedure is suitable for scalable production of heterojunctions for spintronic applications. PMID:26940024

  2. Preconcentration, speciation and determination of ultra trace amounts of mercury by modified octadecyl silica membrane disk/electron beam irradiation and cold vapor atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ashkenani, Hamid [Department of Chemistry, Yazd University, Yazd (Iran, Islamic Republic of); Dadfarnia, Shayessteh [Department of Chemistry, Yazd University, Yazd (Iran, Islamic Republic of)], E-mail: sdadfarnia@yazduni.ac.ir; Shabani, Ali Mohammad Haji; Jaffari, Abbas Ali [Department of Chemistry, Yazd University, Yazd (Iran, Islamic Republic of); Behjat, Abbas [Department of physics, Yazd University, Yazd (Iran, Islamic Republic of)

    2009-01-15

    Mercury (II) and methyl mercury cations at the Sub-ppb level were adsorbed quantitatively from aqueous solution onto an octadecyl-bonded silica membrane disk modified by 2-[(2-mercaptophyenylimino)methyl] phenol (MPMP). The trapped mercury was then eluted with 3 ml ethanol and Hg{sup 2+} ion was directly measured by cold vapor atomic absorption spectrometry, utilizing tin (II) chloride. Total mercury (Hgt) was determined after conversion of MeHg{sup +} into Hg{sup 2+} ion by electron beam irradiation. A sample volume of 1500 ml resulted in a preconcentration factor of 500 and the precision for a sampling volume of 500 ml at a concentration of 2.5 {mu}g l{sup -1} (n = 7) was 3.1%. The limit of detection of the proposed method is 3.8 ng l{sup -1}. The method was successfully applied to analysis of water samples, and the accuracy was assessed via recovery experiment.

  3. Measurement scheme for a ground-state parity non-conserving (PNC) measurement in a cesium atomic beam via two-pathway coherent control

    Science.gov (United States)

    Choi, Jungu; Elliott, Dan; Elliott's Lab Team

    2016-05-01

    We present a detailed analysis of an experimental setup for parity non-conserving (PNC) measurements in a cesium atomic beam. We employ a parallel-plate transmission line (PPTL) structure and highly reflective cylindrical mirrors to form a microwave cavity resonator to excite the PNC transitions in the cesium hyperfine ground states. In addition, a variable external dc field is applied to observe the Stark-induced transition, which would interfere with the PNC transition as the dc field amplitude changes. Finally, strong Raman lasers are used to excite the ground hyperfine transition. The Raman fields interfere with the weak transitions, and by varying the phase difference between the Raman fields and the microwave fields, we would infer the weak transition amplitudes from the signal modulation. The experimental setup requires maintaining coherent phase relations between all fields, well-characterized dc and rf field patterns, the two co-propagating Raman lasers, and suppression of the magnetic dipole contribution. Our analysis of the field modes supported by the PPTL structure indicates that with a moderate rf power and a few tens of seconds of data collection time, the PNC measurement of less than 3% uncertainty would be feasible.

  4. Atomic force microscopy characterization of the chemical contrast of nanoscale patterns fabricated by electron beam lithography on polyethylene glycol oxide thin films

    International Nuclear Information System (INIS)

    The present paper shows that atomic force microscopy (AFM) imaging of friction force and phase lag in ambient air can be used to characterize the chemical contrast induced by electron beam (EB) irradiation on polyethylene glycol oxide (PEO) surface. Time-of-flight secondary emission mass spectroscopy measurements showed that the EB irradiation generates chemical contrast on PEO surface by decreasing the ether bond density. The AFM measurements showed smaller phase lag and lower friction and adhesive forces on the EB irradiated PEO surface, as compared to the non-irradiated PEO surface. While the chemical contrast in friction force had a linear dependence on the EB irradiation dose, the dependence of the chemical contrast in the phase lag was strongly non-linear. As the friction and adhesive forces depended on the AFM probe hydrophilicity and air humidity, the contrast in friction and adhesive forces is ascribed to different capillary condensation of ambient water vapour at the AFM tip contact with the EB irradiated and non-irradiated PEO surfaces, respectively.

  5. Beam-Beam Effects

    OpenAIRE

    Herr, W; Pieloni, T.

    2016-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities.

  6. Beam-Beam Effects

    CERN Document Server

    Herr, W

    2014-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities.

  7. Characterization of the Plasma Edge for Technique of Atomic Helium Beam in the CIEMAT Fusion Device; Caracterizacion del Borde del Plasma del Dispositivo de Fusion TJ-II del CIEMAT mediante el Diagnostico del Haz Supersonico de Helio

    Energy Technology Data Exchange (ETDEWEB)

    Hidalgo, A.

    2003-07-01

    In this report, the measurement of Electron Temperature and Density in the Boundary Plasma of TJ-II with a Supersonic Helium Beam Diagnostic and work devoted to the upgrading of this technique are described. Also, simulations of Laser Induced Fluorescence (LIF) studies of level populations of electronically excited He atoms are shown. This last technique is now being installed in the CIEMAT fusion device. (Author ) 36 refs.

  8. Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling

    International Nuclear Information System (INIS)

    The fabrication and performance of multilayer Al2O3/Ta2O5 Fresnel zone plates in the hard X-ray range and a discussion of possible future developments considering available materials are reported. Fresnel zone plates (FZPs) recently showed significant improvement by focusing soft X-rays down to ∼10 nm. In contrast to soft X-rays, generally a very high aspect ratio FZP is needed for efficient focusing of hard X-rays. Therefore, FZPs had limited success in the hard X-ray range owing to difficulties of manufacturing high-aspect-ratio zone plates using conventional techniques. Here, employing a method of fabrication based on atomic layer deposition (ALD) and focused ion beam (FIB) milling, FZPs with very high aspect ratios were prepared. Such multilayer FZPs with outermost zone widths of 10 and 35 nm and aspect ratios of up to 243 were tested for their focusing properties at 8 keV and shown to focus hard X-rays efficiently. This success was enabled by the outstanding layer quality thanks to ALD. Via the use of FIB for slicing the multilayer structures, desired aspect ratios could be obtained by precisely controlling the thickness. Experimental diffraction efficiencies of multilayer FZPs fabricated via this combination reached up to 15.58% at 8 keV. In addition, scanning transmission X-ray microscopy experiments at 1.5 keV were carried out using one of the multilayer FZPs and resolved a 60 nm feature size. Finally, the prospective of different material combinations with various outermost zone widths at 8 and 17 keV is discussed in the light of the coupled wave theory and the thin-grating approximation. Al2O3/Ir is outlined as a promising future material candidate for extremely high resolution with a theoretical efficiency of more than 20% for as small an outermost zone width as 10 nm at 17 keV

  9. Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling.

    Science.gov (United States)

    Mayer, Marcel; Keskinbora, Kahraman; Grévent, Corinne; Szeghalmi, Adriana; Knez, Mato; Weigand, Markus; Snigirev, Anatoly; Snigireva, Irina; Schütz, Gisela

    2013-05-01

    Fresnel zone plates (FZPs) recently showed significant improvement by focusing soft X-rays down to ~10 nm. In contrast to soft X-rays, generally a very high aspect ratio FZP is needed for efficient focusing of hard X-rays. Therefore, FZPs had limited success in the hard X-ray range owing to difficulties of manufacturing high-aspect-ratio zone plates using conventional techniques. Here, employing a method of fabrication based on atomic layer deposition (ALD) and focused ion beam (FIB) milling, FZPs with very high aspect ratios were prepared. Such multilayer FZPs with outermost zone widths of 10 and 35 nm and aspect ratios of up to 243 were tested for their focusing properties at 8 keV and shown to focus hard X-rays efficiently. This success was enabled by the outstanding layer quality thanks to ALD. Via the use of FIB for slicing the multilayer structures, desired aspect ratios could be obtained by precisely controlling the thickness. Experimental diffraction efficiencies of multilayer FZPs fabricated via this combination reached up to 15.58% at 8 keV. In addition, scanning transmission X-ray microscopy experiments at 1.5 keV were carried out using one of the multilayer FZPs and resolved a 60 nm feature size. Finally, the prospective of different material combinations with various outermost zone widths at 8 and 17 keV is discussed in the light of the coupled wave theory and the thin-grating approximation. Al2O3/Ir is outlined as a promising future material candidate for extremely high resolution with a theoretical efficiency of more than 20% for as small an outermost zone width as 10 nm at 17 keV. PMID:23592622

  10. Water equivalence study of some phantoms based on effective photon energy, effective atomic numbers and electron densities for clinical MV X-ray and Co-60 γ-ray beams

    Science.gov (United States)

    Kurudirek, Murat

    2013-02-01

    A previously proposed procedure has been applied to some water equivalent phantoms namely PMMA, Polystyrene, Solid Water (WT1), RW3 and ABS for the first time to compute effective photon energy (Eeff), effective atomic numbers (Zeff) and electron densities (neeff) for different MV X-ray beams and Co-60 gamma beam which are heterogeneous in energy. For the purpose of the present investigation, effective atomic cross-sections of the given materials have been determined first to obtain effective photon energies which were further used for calculation of Zeff and neeff. Similar procedure was adopted for Co-60 γ-rays to check the validity of the present method. Results were found to be quite satisfactory. When it comes to the water equivalence, the Eeff results showed that the RW3 and ABS phantoms are more effective for 6 MV beam whereas RW3 and Polystyrene are more effective for 15 MV and Co-60 beams, respectively. The ABS and WT1 phantoms have better water equivalences than the others according to the Zeff and neeff results, respectively.

  11. Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Marcel; Keskinbora, Kahraman; Grévent, Corinne, E-mail: grevent@is.mpg.de [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569 Stuttgart (Germany); Szeghalmi, Adriana [Friedrich-Schiller-Universität Jena, Albert-Einstein-Strasse 15, D-07745 Jena (Germany); Knez, Mato [CIC nanoGUNE Consolider, Tolosa Hiribidea 76, E-20018 Donostia-San Sebastian (Spain); Basque Foundation for Science, Alameda Urquijo 36-5, E-48011 Bilbao (Spain); Weigand, Markus [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569 Stuttgart (Germany); Snigirev, Anatoly; Snigireva, Irina [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, F-38043 Grenoble (France); Schütz, Gisela [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569 Stuttgart (Germany)

    2013-05-01

    The fabrication and performance of multilayer Al{sub 2}O{sub 3}/Ta{sub 2}O{sub 5} Fresnel zone plates in the hard X-ray range and a discussion of possible future developments considering available materials are reported. Fresnel zone plates (FZPs) recently showed significant improvement by focusing soft X-rays down to ∼10 nm. In contrast to soft X-rays, generally a very high aspect ratio FZP is needed for efficient focusing of hard X-rays. Therefore, FZPs had limited success in the hard X-ray range owing to difficulties of manufacturing high-aspect-ratio zone plates using conventional techniques. Here, employing a method of fabrication based on atomic layer deposition (ALD) and focused ion beam (FIB) milling, FZPs with very high aspect ratios were prepared. Such multilayer FZPs with outermost zone widths of 10 and 35 nm and aspect ratios of up to 243 were tested for their focusing properties at 8 keV and shown to focus hard X-rays efficiently. This success was enabled by the outstanding layer quality thanks to ALD. Via the use of FIB for slicing the multilayer structures, desired aspect ratios could be obtained by precisely controlling the thickness. Experimental diffraction efficiencies of multilayer FZPs fabricated via this combination reached up to 15.58% at 8 keV. In addition, scanning transmission X-ray microscopy experiments at 1.5 keV were carried out using one of the multilayer FZPs and resolved a 60 nm feature size. Finally, the prospective of different material combinations with various outermost zone widths at 8 and 17 keV is discussed in the light of the coupled wave theory and the thin-grating approximation. Al{sub 2}O{sub 3}/Ir is outlined as a promising future material candidate for extremely high resolution with a theoretical efficiency of more than 20% for as small an outermost zone width as 10 nm at 17 keV.

  12. Intense positron beams: linacs

    International Nuclear Information System (INIS)

    Beams of monoenergetic positrons with energies of a few eV to many keV have been used in experiments in atomic physics, solid-state physics and materials science. The production of positron beams from a new source, an electron linac, is described. Intense, pulsed beams of low-energy positrons were produced by a high-energy beam from an electron linac. The production efficiency, moderator geometry, beam spot size and other positron beam parameters were determined for electrons with energies from 60 to 120 MeV. Low-energy positron beams produced with a high-energy electron linac can be of much higher intensity than those beams currently derived from radioactive sources. These higher intensity beams will make possible positron experiments previously infeasible. 10 references, 1 figure

  13. Understanding time-resolved processes in atomic-layer etching of ultra-thin Al{sub 2}O{sub 3} film using BCl{sub 3} and Ar neutral beam

    Energy Technology Data Exchange (ETDEWEB)

    Jhon, Young I.; Jhon, Young Min, E-mail: ymjhon@kist.re.kr [Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Min, Kyung S. [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Yeom, G. Y., E-mail: gyyeom@skku.edu [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2014-09-01

    We scrutinize time-resolved processes occurring in atomic-layer etching (ALET) of ultra-thin Al{sub 2}O{sub 3} film using BCl{sub 3} gas and Ar neutral beam by employing density functional theory calculations and experimental measurements. BCl{sub 3} gas is found to be preferentially chemisorbed on Al{sub 2}O{sub 3}(100) in trans form with the surface atoms creating O-B and Al-Cl contacts. We disclose that the most likely sequence of etching events involves dominant detachment of Al-associated moieties at early etching stages in good agreement with our concurrent experiments on tracking Al{sub 2}O{sub 3} surface compositional variations during Ar bombardment. In this etching regime, we find that ALET requires half the maximum reaction energy of conventional plasma etching, which greatly increases if the etching sequence changes.

  14. Interferometry with atoms

    International Nuclear Information System (INIS)

    Optics and interferometry with matter waves is the art of coherently manipulating the translational motion of particles like neutrons, atoms and molecules. Coherent atom optics is an extension of techniques that were developed for manipulating internal quantum states. Applying these ideas to translational motion required the development of techniques to localize atoms and transfer population coherently between distant localities. In this view position and momentum are (continuous) quantum mechanical degrees of freedom analogous to discrete internal quantum states. In our contribution we start with an introduction into matter wave optics in sect. 1, discuss coherent atom optics and atom interferometry techniques for molecular beams in sect. 2 and for trapped atoms in sect. 3. In sect. 4 we then describe tools and experiments that allow to probe the evolution of quantum states of many-body systems by atom interference.

  15. Study of high efficiency excited helium atom beam production for electric field measurements with high spatial and temporal resolution by laser-induced fluorescence method. JAERI's nuclear research promotion program, H13-013 (Contract research)

    International Nuclear Information System (INIS)

    The objective of this study is to develop a highly efficient method in producing a pulsed supersonic beam of 21S metastable He atoms for the laser induced fluorescence (LIF) diagnostics making use of the Stark effects in forbidden transition of HeI, in order to apply the LIF method to measurements of localized electric fields in a deuterium plasma in an Inertial Electrostatic Confinement (IEC) fusion neutron/proton source. Firstly, we studied numerically the dependence of excitation efficiency on electron temperature and density in a plasma exciter, and found that an efficiency of several times of 10-4 is achievable, which is very encouraging in comparison with the typical efficiency limit of 10-6 by conventional methods. We then investigated a couple of schemes for producing sufficiently dense plasma under an extremely low gas pressure condition in the experiments. As a result, we could have developed successfully a compact magnetron-discharge-based system which can produce a race-track-shaped plasma capable of strong interaction with the injected supersonic beam atoms. Also, we have designed and fabricated an injector of pulsed supersonic He beam, and its performance characteristics were studied. It is found that well collimated beams can be produced with a high repetition rate (> 1 Hz) as expected. The achieved on-axis density is found to be above 1/10 of the target density of 1013 cm-3 initially envisaged for the LIF diagnostics. Further enhanced density is found achievable through the optimization of the configuration. (author)

  16. A slow gravity compensated atom laser

    DEFF Research Database (Denmark)

    Kleine Büning, G.; Will, J.; Ertmer, W.;

    2010-01-01

    We report on a slow guided atom laser beam outcoupled from a Bose–Einstein condensate of 87Rb atoms in a hybrid trap. The acceleration of the atom laser beam can be controlled by compensating the gravitational acceleration and we reach residual accelerations as low as 0.0027 g. The outcoupling me...

  17. Elastic and inelastic scattering of cesium, cesium iodide, and cesium chloride by argon and xenon in the crossed atomic and molecular beams

    International Nuclear Information System (INIS)

    Velocity and angular distributions of cesium atoms and two cesium halide molecules scattered by rare gas atoms have been measured for the following systems at the indicated initial relative collision energies, anti E: Cs + Ar, anti E = 0.94, 1.29, and 1.85 kcal/mole; Cs + Xe, E = 1.15, 1.91, and 3.10 kcal/mole; Csl + Ar, anti E = 1.06, 1.46, and 2.08 kcal/mole; CsI + Ar, anti E = 1.36, 1.63, and 1.94 kcal/mole; CsI + Xe, anti E = 1.52, 2.52, and 4.09 kcal/mole. At the collision energies indicated the atom-atom scattering can only be elastic. Thus the experiments with those systems can be used for apparatus calibration and a standard of comparison for the diatom-atom experiments. The velocity distributions in the diatom-atom systems are analyzed for the relative contributions of elastic and inelastic scattering

  18. Atom-Light Hybrid Interferometer.

    Science.gov (United States)

    Chen, Bing; Qiu, Cheng; Chen, Shuying; Guo, Jinxian; Chen, L Q; Ou, Z Y; Zhang, Weiping

    2015-07-24

    A new type of hybrid atom-light interferometer is demonstrated with atomic Raman amplification processes replacing the beam splitting elements in a traditional interferometer. This nonconventional interferometer involves correlated optical and atomic waves in the two arms. The correlation between atoms and light developed with the Raman process makes this interferometer different from conventional interferometers with linear beam splitters. It is observed that the high-contrast interference fringes are sensitive to the optical phase via a path change as well as the atomic phase via a magnetic field change. This new atom-light correlated hybrid interferometer is a sensitive probe of the atomic internal state and should find wide applications in precision measurement and quantum control with atoms and photons. PMID:26252684

  19. Plasma For-Injector of Separable Material Based on the Beam-Plasma Discharge for Ion-Atomic Separation Technologies. Conception

    CERN Document Server

    Skibenko, E I; Yuferov, V B

    2010-01-01

    In the paper, the functional definition of a plasma for-injector of separable material is presented, and the requirements to it are formulated. The version of a device for the material separation into elements based on the beam-plasma discharge is under consideration. The dimensions of a pilot separating device are determined. The following quantities are estimated: the particle concentration per unit length of the separating device, effective length of the beam-plasma interaction (BPI) within the separating device, dynamics of a plasma density increase for metallic uranium, and thermal characteristics of a phase transformation unit. A conclusion was drawn on the expedience and validity of the development and realization of a plasma for-injector for separating devices and technologies basing on the beam-plasma mechanism of formation and heating of a highly ionized plasma.

  20. Beam-beam effects

    Energy Technology Data Exchange (ETDEWEB)

    Zholents, A.

    1994-12-01

    The term beam-beam effects is usually used to designate different phenomena associated with interactions of counter-rotating beams in storage rings. Typically, the authors speak about beam-beam effects when such interactions lead to an increase of the beam core size or to a reduction of the beam lifetime or to a growth of particle`s population in the beam halo and a correspondent increase of the background. Although observations of beam-beam effects are very similar in most storage rings, it is very likely that every particular case is largely unique and machine-dependent. This constitutes one of the problems in studying the beam-beam effects, because the experimental results are often obtained without characterizing a machine at the time of the experiment. Such machine parameters as a dynamic aperture, tune dependencies on amplitude of particle oscillations and energy, betatron phase advance between the interaction points and some others are not well known, thus making later analysis uncertain. The authors begin their discussion with demonstrations that beam-beam effects are closely related to non linear resonances. Then, they will show that a non linearity of the space charge field is responsible for the excitation of these resonances. After that, they will consider how beam-beam effects could be intensified by machine imperfections. Then, they will discuss a leading mechanism for the formation of the beam halo and will describe a new technique for beam tails and lifetime simulations. They will finish with a brief discussion of the coherent beam-beam effects.

  1. Order within disorder: The atomic structure of ion-beam sputtered amorphous tantala (a-Ta{sub 2}O{sub 5})

    Energy Technology Data Exchange (ETDEWEB)

    Bassiri, Riccardo, E-mail: rbassiri@stanford.edu; Liou, Franklin; Lin, Angie C.; Byer, Robert L.; Route, Roger K.; Fejer, Martin M. [E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305 (United States); Abernathy, Matthew R.; Gustafson, Eric K. [LIGO Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Kim, Namjun; Stebbins, Jonathan F. [Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305 (United States); Mehta, Apurva; Shyam, Badri [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Hart, Martin; MacLaren, Ian; Martin, Iain W.; Rowan, Sheila [SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

    2015-03-01

    Amorphous tantala (a-Ta{sub 2}O{sub 5}) is a technologically important material often used in high-performance coatings. Understanding this material at the atomic level provides a way to further improve performance. This work details extended X-ray absorption fine structure measurements of a-Ta{sub 2}O{sub 5} coatings, where high-quality experimental data and theoretical fits have allowed a detailed interpretation of the nearest-neighbor distributions. It was found that the tantalum atom is surrounded by four shells of atoms in sequence; oxygen, tantalum, oxygen, and tantalum. A discussion is also included on how these models can be interpreted within the context of published crystalline Ta{sub 2}O{sub 5} and other a-T{sub 2}O{sub 5} studies.

  2. Atomic clocks: the atoms as primary time and frequency standards

    International Nuclear Information System (INIS)

    In this article, we present the atomic clock as time and frequency standard and as one of the peaceful uses of atoms for development. In the first part, we present the general principles of time and frequency metrology and the key role of the caesium atom in this field as well as the main applications of atomic clocks. In the second part we introduce the different clock technologies based on Ramsey method, with a focus on atomic beam clocks and atomic fountain clocks. (author)

  3. Atom beam triangulation of organic layers at 100 meV normal energy: self-assembled perylene on Ag(1 1 0) at room temperature

    Science.gov (United States)

    Kalashnyk, Nataliya; Khemliche, Hocine; Roncin, Philippe

    2016-02-01

    The controlled growth of organic layers on surfaces is still waiting for an in-situ reliable technique that would allow their quality to be monitored and improved. Here we show that the growth of a perylene monolayer deposited on Ag(1 1 0) at room temperature can be tracked with low energy atoms in a regime where the energy perpendicular to the layer is less than 0.1 eV and below the organic film damage threshold. The image processing required for this atom triangulation technique is described in detail.

  4. Atom beam triangulation of organic layers at 100 meV normal energy: self-assembled perylene on Ag(110) at room temperature

    CERN Document Server

    Kalashnyk, Nataliya

    2015-01-01

    The controlled growth of organic layer on surface is still awaiting for an on-line reliable monitoring that would allow improvement of its quality. We show here that the self-assembly of the perylene monolayer deposited on Ag(110) at room temperature can be tracked with low energy atoms in a regime where the energy perpendicular to the layer is less than 0.1 eV preventing damage to the layer. The image processing required for this triangulation technique with atoms is described in details.

  5. Some regularities in distribution of effective cross sections for excitation of KrI atoms with an electron beam in the 4p 5 np series

    International Nuclear Information System (INIS)

    The absolute values of effective cross sections for the krypton 4p 5 np excited states (n = 5,6,7) are measured through the electron beam pulsed method with temporary radiation time base. Impact of indirect processes of settling these states on the form of optical excitation functions of the corresponding spectral lines is studied. 4 refs., 1 fig., 2 tabs

  6. 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

    International Nuclear Information System (INIS)

    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

  7. Atom laser divergence

    OpenAIRE

    Le Coq, Yann; Thywissen, Joseph H.; Rangwala, Sadiq A.; Gerbier, Fabrice; Richard, Simon; Delannoy, Guillaume; Bouyer, Philippe; Aspect, Alain

    2001-01-01

    We measure the angular divergence of a quasi-continuous, rf-outcoupled, free-falling atom laser as a function of the outcoupling frequency. The data is compared to a Gaussian-beam model of laser propagation that generalizes the standard formalism of photonic lasers. Our treatment includes diffraction, magnetic lensing, and interaction between the atom laser and the condensate. We find that the dominant source of divergence is the condensate-laser interaction.

  8. Atomic collisions involving pulsed positrons

    DEFF Research Database (Denmark)

    Merrison, J. P.; Bluhme, H.; Field, D.;

    2000-01-01

    Conventional slow positron beams have been widely and profitably used to study atomic collisions and have been instrumental in understanding the dynamics of ionization. The next generation of positron atomic collision studies are possible with the use of charged particle traps. Not only can large...... instantaneous intensities be achieved with in-beam accumulation, but more importantly many orders of magnitude improvement in energy and spatial resolution can be achieved using positron cooling. Atomic collisions can be studied on a new energy scale with unprecedented precion and control. The use of...... accelerators for producing intense positron pulses will be discussed in the context of atomic physics experiments....

  9. Dielectric barrier discharge source for supersonic beams

    Energy Technology Data Exchange (ETDEWEB)

    Luria, K.; Lavie, N.; Even, U. [Sackler School of Chemistry, Tel Aviv University, Tel Aviv 69978 (Israel)

    2009-10-15

    We present a new excitation source for pulsed supersonic beams. The excitation is based on dielectric barrier discharge in the beam. It produces cold beams of metastable atoms, dissociated neutral atoms from molecular precursors, and both positive and negative ions with high efficiency and reliability.

  10. Quantum correlations by four-wave mixing in an atomic vapor in a non-amplifying regime: a quantum beam splitter for photons

    CERN Document Server

    Glorieux, Quentin; Guibal, Samuel; Likforman, Jean-Pierre; Coudreau, Thomas; 10.1103/PhysRevA.84.053826

    2011-01-01

    We study the generation of intensity quantum correlations using four-wave mixing in a rubidium vapor. The absence of cavity in these experiments allows to deal with several spatial modes simultaneously. In the standard, amplifying, configuration, we measure relative intensity squeezing up to 9.2 dB below the standard quantum limit. We also theoretically identify and experimentally demonstrate an original regime where, despite no overall amplification, quantum correlations are generated. In this regime a four-wave mixing set-up can therefore play the role of a photonic beam splitter with non--classical properties, i.e. a device that splits a coherent state input into two quantum correlated beams.

  11. Cluster ion beam evaporation

    International Nuclear Information System (INIS)

    Cluster ions can be made by the supercooling due to adiabatic expansion of substances to be vaporized which are ejected from a nozzle. This paper is described on the recent progress of studies concerning the cluster beam. The technique of cluster ion beam has been applied for the studies of thermonuclear plasma, the fabrication of thin films, crystal growth and electronic devices. The density of cluster ion beam is larger than that of atomic ion beam, and the formation of thin films can be easily done in high vacuum. This method is also useful for epitaxial growth. Metallic vapour cluster beam was made by the help of jetting rare gas beam. Various beam sources were developed. The characteristics of these sources were measured and analyzed. (Kato, T.)

  12. Coherent Atom Optics with fast metastable rare gas atoms

    Science.gov (United States)

    Grucker, J.; Baudon, J.; Karam, J.-C.; Perales, F.; Bocvarski, V.; Vassilev, G.; Ducloy, M.

    2006-12-01

    Coherent atom optics experiments making use of an ultra-narrow beam of fast metastable atoms generated by metastability exchange are reported. The transverse coherence of the beam (coherence radius of 1.7 μm for He*, 1.2 μm for Ne*, 0.87 μm for Ar*) is demonstrated via the atomic diffraction by a non-magnetic 2μm-period reflection grating. The combination of the non-scalar van der Waals (vdW) interaction with the Zeeman interaction generated by a static magnetic field gives rise to "vdW-Zeeman" transitions among Zeeman sub-levels. Exo-energetic transitions of this type are observed with Ne*(3P2) atoms traversing a copper micro-slit grating. They can be used as a tunable beam splitter in an inelastic Fresnel bi-prism atom interferometer.

  13. A comparison study between atomic and ionic nitrogen doped carbon films prepared by ion beam assisted cathode arc deposition at various pulse frequencies

    International Nuclear Information System (INIS)

    A comparison study of microstructure and bonds composition of carbon nitride (CNx) films fabricated at atomic and ionic nitrogen source by pulse cathode arc method was presented. The relative fractions of CN/CC bonds, N-sp3C/N-sp2C and graphite-like/pyridine-like N bonding configurations in the CN films were evaluated by combining C1s and N1s X-ray photoelectron spectroscopy with the hardness and optical band gap measurement. The dependence of microstructure (quantity, size and disordering degree of Csp2 clusters) of CNx films on the nitrogen source and pulse frequency was determined by Raman spectroscopy. Films with high atomic ratio of nitrogen/carbon (0.17) and high hardness were produced at ionic nitrogen source and low pulse frequency. The results showed that ionic nitrogen source facilitated the formation of CN bonds and N-sp2C bonding configurations (mainly in graphite-like N form). Moreover presenting an optimum pulse frequency (∼10 Hz) leaded to the most nitrogen coordinated with sp3-C and the highest ratio of CN/CC bonds in the CNx films. An equilibrium action mechanism might exist between the quantity and energy of carbon and nitrogen ions/atoms, giving more nitrogen-incorporated carbon materials. These allow us to obtain the high content of N-Csp3 bonding and expected bonding structure by optimizing pulse frequency and nitrogen source.

  14. An ultra-bright atom laser

    International Nuclear Information System (INIS)

    We present a novel, ultra-bright atom laser and an ultra-cold thermal atom beam. Using rf-radiation we strongly couple the magnetic hyperfine levels of 87Rb atoms in a trapped Bose–Einstein condensate. The resulting time-dependent adiabatic potential forms a trap, which at low rf-frequencies opens just below the condensate and thus allows an extremely bright well-collimated atom laser beam to emerge. As opposed to traditional atom lasers based on weak coupling of the magnetic hyperfine levels, this technique allows us to outcouple atoms at an arbitrarily large rate. We achieve a flux of 4×107 atom s-1, a seven fold increase compared to the brightest atom lasers to date. Furthermore, we demonstrate by two orders of magnitude the coldest thermal atom beam (200 nK). (paper)

  15. A crossed molecular beam and ab-initio investigation of the reaction of boron monoxide (BO; X2Σ+) with methylacetylene (CH3CCH; X1A1): competing atomic hydrogen and methyl loss pathways.

    Science.gov (United States)

    Maity, Surajit; Parker, Dorian S N; Dangi, Beni B; Kaiser, Ralf I; Fau, Stefan; Perera, Ajith; Bartlett, Rodney J

    2013-11-21

    The gas-phase reaction of boron monoxide ((11)BO; X(2)Σ(+)) with methylacetylene (CH3CCH; X(1)A1) was investigated experimentally using crossed molecular beam technique at a collision energy of 22.7 kJ mol(-1) and theoretically using state of the art electronic structure calculation, for the first time. The scattering dynamics were found to be indirect (complex forming reaction) and the reaction proceeded through the barrier-less formation of a van-der-Waals complex ((11)BOC3H4) followed by isomerization via the addition of (11)BO(X(2)Σ(+)) to the C1 and/or C2 carbon atom of methylacetylene through submerged barriers. The resulting (11)BOC3H4 doublet radical intermediates underwent unimolecular decomposition involving three competing reaction mechanisms via two distinct atomic hydrogen losses and a methyl group elimination. Utilizing partially deuterated methylacetylene reactants (CD3CCH; CH3CCD), we revealed that the initial addition of (11)BO(X(2)Σ(+)) to the C1 carbon atom of methylacetylene was followed by hydrogen loss from the acetylenic carbon atom (C1) and from the methyl group (C3) leading to 1-propynyl boron monoxide (CH3CC(11)BO) and propadienyl boron monoxide (CH2CCH(11)BO), respectively. Addition of (11)BO(X(2)Σ(+)) to the C1 of methylacetylene followed by the migration of the boronyl group to the C2 carbon atom and/or an initial addition of (11)BO(X(2)Σ(+)) to the sterically less accessible C2 carbon atom of methylacetylene was followed by loss of a methyl group leading to the ethynyl boron monoxide product (HCC(11)BO) in an overall exoergic reaction (78 ± 23 kJ mol(-1)). The branching ratios of these channels forming CH2CCH(11)BO, CH3CC(11)BO, and HCC(11)BO were derived to be 4 ± 3%, 40 ± 5%, and 56 ± 15%, respectively; these data are in excellent agreement with the calculated branching ratios using statistical RRKM theory yielding 1%, 38%, and 61%, respectively. PMID:23651442

  16. Atomic scale modelling of nanosize Ni sub 3 Al cluster beam deposition on Al, Ni and Ni sub 3 Al (1 1 1) surfaces

    CERN Document Server

    Kharlamov, V S; Hou, M

    2002-01-01

    The slowing down of Ni sub 3 Al clusters on a Al, Ni and Ni sub 3 Al (1 1 1) surfaces is studied by atomic scale modelling. The semi-grand canonical metropolis Monte Carlo is used for the preparation of isolated clusters at thermodynamic equilibrium. The cluster deposition on the surface is studied in detail by classical Molecular Dynamics simulations that include a model to account for electron-phonon coupling. Long- and short-range orders in the cluster are evaluated as functions of temperature in an impact energy range between 0 and 1.5 eV/atom. The interaction between the Ni sub 3 Al cluster and an Al surface is characterised low short range (chemical) disorder. No sizeable epitaxy is found, subsequent to the impact. In contrast, in the case of Ni and Ni sub 3 Al substrates, which are harder materials than aluminium, the chemical disorder is higher and epitaxial accommodation is possible. With these substrates, chemical disorder in the cluster is an increasing function of the impact energy, as well as of ...

  17. Atomic scale modelling of nanosize Ni3Al cluster beam deposition on Al, Ni and Ni3Al (1 1 1) surfaces

    International Nuclear Information System (INIS)

    The slowing down of Ni3Al clusters on a Al, Ni and Ni3Al (1 1 1) surfaces is studied by atomic scale modelling. The semi-grand canonical metropolis Monte Carlo is used for the preparation of isolated clusters at thermodynamic equilibrium. The cluster deposition on the surface is studied in detail by classical Molecular Dynamics simulations that include a model to account for electron-phonon coupling. Long- and short-range orders in the cluster are evaluated as functions of temperature in an impact energy range between 0 and 1.5 eV/atom. The interaction between the Ni3Al cluster and an Al surface is characterised low short range (chemical) disorder. No sizeable epitaxy is found, subsequent to the impact. In contrast, in the case of Ni and Ni3Al substrates, which are harder materials than aluminium, the chemical disorder is higher and epitaxial accommodation is possible. With these substrates, chemical disorder in the cluster is an increasing function of the impact energy, as well as of temperature when the impact energy is low enough. The cluster epitaxy is enhanced by both the temperature and the impact energy. A direct correlation between epitaxy and chemical disordering is found during the accommodation of the cluster with the surface

  18. Evanescent Wave Atomic Mirror

    Science.gov (United States)

    Ghezali, S.; Taleb, A.

    2008-09-01

    A research project at the "Laboratoire d'électronique quantique" consists in a theoretical study of the reflection and diffraction phenomena via an atomic mirror. This poster presents the principle of an atomic mirror. Many groups in the world have constructed this type of atom optics experiments such as in Paris-Orsay-Villetaneuse (France), Stanford-Gaithersburg (USA), Munich-Heidelberg (Germany), etc. A laser beam goes into a prism with an incidence bigger than the critical incidence. It undergoes a total reflection on the plane face of the prism and then exits. The transmitted resulting wave out of the prism is evanescent and repulsive as the frequency detuning of the laser beam compared to the atomic transition δ = ωL-ω0 is positive. The cold atomic sample interacts with this evanescent wave and undergoes one or more elastic bounces by passing into backward points in its trajectory because the atoms' kinetic energy (of the order of the μeV) is less than the maximum of the dipolar potential barrier ℏΩ2/Δ where Ω is the Rabi frequency [1]. In fact, the atoms are cooled and captured in a magneto-optical trap placed at a distance of the order of the cm above the prism surface. The dipolar potential with which interact the slow atoms is obtained for a two level atom in a case of a dipolar electric transition (D2 Rubidium transition at a wavelength of 780nm delivered by a Titane-Saphir laser between a fundamental state Jf = l/2 and an excited state Je = 3/2). This potential is corrected by an attractive Van der Waals term which varies as 1/z3 in the Lennard-Jones approximation (typical atomic distance of the order of λ0/2π where λ0 is the laser wavelength) and in 1/z4 if the distance between the atom and its image in the dielectric is big in front of λ0/2π. This last case is obtained in a quantum electrodynamic calculation by taking into account an orthornormal base [2]. We'll examine the role of spontaneous emission for which the rate is inversely

  19. Effect of laser beam non-uniformity and the AC stark shift on the two-photon resonant three-photon ionization process of the cesium atom

    International Nuclear Information System (INIS)

    The Ac Stark effect and the effect of laser beam non-uniformity on the two-photon resonant three-photon ionization spectrum of cesium is investigated. The non-uniformity due to the temporal and the spatial variations of the pumping laser makes the ionization spectrum non-symmetric and shifts the peak frequency of the excited-state population from the peak frequency of the ionization yield. The order of the non-linearity of the ionization process is also studied near resonances, and it is found that the minimum of the curve is close to the peak frequency of the excited-state spectrum. Ways of applying these results to studies of autoionizing states are suggested

  20. Electrons and atoms in intense laser fields

    International Nuclear Information System (INIS)

    Several non-linear effects that show up when electrons and atoms interact with strong laser fields are considered. Thomson scattering, electron potential scattering in the presence of a laser beam, atomic ionization by strong laser fields, the refraction of electrons by laser beams and the Kapitza-Dirac effect are discussed. (Author)

  1. 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.

  2. Study on laser atomic spectroscopy

    International Nuclear Information System (INIS)

    Electric discharge type atomic vaporizer is developed for the spectroscopic study on actinide elements. Laser induced fluorescence study on actinide elements is performed by using this high temperature type atomizer. For the effective photoionization of elements, copper vapor laser pumped dye laser and electron beam heating type atomic vaporizer are built and their characteristics are measured. In addition, resonance ionization mass spectroscopic analysis for lead sample as well as laser induced fluorescence study on uranium sample in solution phase is made. (Author)

  3. Economic feasibility study to Raise the operational capacity of the Electron Beam Accelerator at the National Centre for Radiation Research and Technology, atomic Energy Authority, Egypt

    International Nuclear Information System (INIS)

    The study aims to investigate the economic feasibility to raise the operational capacity of the accelerator at the National Center for Radiation Research and Technology, Atomic Energy Authority, Egypt, through proposal of additional processing of power cables as it have 4 thousand operating hours per year of total 6 thousand hours per year. The study involved three sections; the first section included the technical aspects and marketing, the second section was concerned with financial analysis, and the third section included the national return of the project. In the first part, the electronic and technical requirements of the accelerator were studied to raise the capacity of the accelerator and to identify the time trend of demand for services in marketing. The second section included the financial feasibility of the project which was carried out through two parts; the first part deal with the analysis of costs of the project including identifying of investment, spending, labor costs, operating expenses, the annual installment of the annual depreciation expense with the total annual costs and operating costs per hour and ton. The second part was carried out to evaluated business profitability of the project, preparation of the annual cash flow, calculation of the internal rate of return, payback period of capital, and the analysis of sensitivity of the project in terms of its ability to achieve profitable business in the event of increasing costs and decreasing revenue. The third section was carried out to raise the operational capacity of the accelerator at the Egyptian Atomic Energy Authority to generate added value for national income, and to study the social rate of return for the project and examine the project's ability to provide new employment opportunities. The study showed the possibility and the importance of the project implemented at the level of private investment and national security.

  4. Optical molasses, laser traps, and ultracold atoms

    International Nuclear Information System (INIS)

    There is dramatic progress in the demonstration of the mechanical effects of light on atoms. The laser cooling and stopping of atoms in an atomic beam were followed by the 3-D cooling and confinement of atoms with laser light. The authors survey the recent major experimental advances and try to point out some interesting physics that can be done in this newly accessible domain of gaseous atoms at low temperatures and possibly high densities

  5. Atomic Beam Merging and Suppression of Alkali Contaminants in Multi Body High Power Targets: Design and Test of Target and Ion Source Prototypes at ISOLDE

    CERN Document Server

    Bouquerel, Elian J A; Lettry, J; Stora, T

    2009-01-01

    The next generation of high power ISOL-facilities will deliver intense and pure radioactive ion beams. Two key issues of developments mandatory for the forthcoming generation of ISOL target-ion source units are assessed and demonstrated in this thesis. The design and production of target and ion-source prototypes is described and dedicated measurements at ISOLDE-CERN of their radioisotope yields are analyzed. The purity of short lived or rare radioisotopes suffer from isobaric contaminants, notably alkalis which are highly volatile and easily ionized elements. Therefore, relying on their chemical nature, temperature controlled transfer lines were equipped with a tube of quartz that aimed at trapping these unwanted elements before they reached the ion source. The successful application yields high alkali-suppression factors for several elements (ie: 80, 82mRb, 126, 142Cs, 8Li, 46K, 25Na, 114In, 77Ga, 95, 96Sr) for quartz temperatures between 300ºC and 1100ºC. The enthalpies of adsorption on quartz were measu...

  6. Atom Chips

    CERN Document Server

    Folman, R; Cassettari, D; Hessmo, B; Maier, T; Schmiedmayer, J; Folman, Ron; Krüger, Peter; Cassettari, Donatella; Hessmo, Björn; Maier, Thomas

    1999-01-01

    Atoms can be trapped and guided using nano-fabricated wires on surfaces, achieving the scales required by quantum information proposals. These Atom Chips form the basis for robust and widespread applications of cold atoms ranging from atom optics to fundamental questions in mesoscopic physics, and possibly quantum information systems.

  7. Precision Survey of X-Rays from $\\overline{p}p (\\overline{p}d)$ Atoms Using the Initial LEAR Beam

    CERN Multimedia

    2002-01-01

    The experiment searches for the K and L X-ray series from @*p~(@*d) atoms, then measures their shift and width relative to QED predictions, and investigates their yields as a function of gas density. \\\\ \\\\ The @* are stopped in 1 atmosphere of H2 (D2) gas in a large aluminium flask whose 1 mm wall thickness eliminates externally produced low energy X-rays. The gas is cooled from a remote helium refrigerator and its temperature varied between 30|0K and 300|0K, giving a density range of 10 and large changes in relative line intensities. With 300~mm|2 area and 250~eV resolution FWHM at 5.9~keV, the Si(Li) X-ray detector penetrates the vacuum to come very close to a large beryllium window. Withstanding the large, charged particle flux from @*p annihilations has required special development of the Si(Li) detector. High purity metals are used for flask, window and detector end-housing to reduce background X-ray lines. A NaI ring suppresses the continuum background that comes principally from Compton scattering in t...

  8. The atomic physics facility at the LBL ECR source

    International Nuclear Information System (INIS)

    A low-energy beam line facility for atomic and surface physics research has been added to the injection line of the ECR source at the LBL 88 in. cyclotron. Beams throughout the periodic table can be delivered to three beam line stations at energies up to 15Q keV. Experiments using this facility inlcude forbidden line emission from the ion beam, ion-atom collisions, merged electron-ion beams and sputtering by highly charged ions. (orig.)

  9. The atomic physics facility at the LBL ECR Source

    International Nuclear Information System (INIS)

    A low energy beam line facility for atomic and surface physics research has been added to the injection line of the ECR source at the LBL 88-Inch Cyclotron. Beams throughout the periodic table can be delivered to 3 beam line stations at energies up to 15 Q keV. Experiments using this facility include forbidden line emission from the ion beam, ion-atom collisions, merged electron-ion beams and sputtering by highly charged ions. 9 refs., 4 figs

  10. Experimental atomic and molecular physics research

    International Nuclear Information System (INIS)

    The Atomic Physics research in the Physics Division consists of five ongoing experimental programs: dissociation and other interactions of energetic molecular ions in solid and gaseous targets; beam-foil research and collision dynamics of heavy ions; photoionization-photoelectron research; spectroscopy of free atoms and molecules, high precision laser-rf double-resonance spectroscopy with atomic and molecular beams; and Moessbauer effect research

  11. The influence of electron beam direction and atomic weight on the ionization cross-section of metals by high-energy electrons

    International Nuclear Information System (INIS)

    The intensities of X-rays generated from samples of Ni3Al, Ni15 at.%Al and (TiNb)3Al were examined over a range of accelerating voltages as a function of diffracting conditions. It was found that the intensities of the X-rays from the heavier element in the alloys may be enhanced, with respect to the signal from the lighter element, when the sample is oriented at symmetry. This occurs for Ni and Ti with respect to the Al intensity in Ni3Al and (TiNb)3Al, even when the systematic row which is excited does not contain a superlattice reflection, and in Ni15 at.%Al which is effectively a disordered alloy. The situation in (TiNb)3Al is more complex, since although the Ti signal is enhanced with respect to the Al signal at symmetry for all reflections, the NbK intensity is not increased relative to the Ti signal but is increased relative to the Al intensity; the magnitude of this increase is about twice as great for reflections which lie in rows which contain superlattice reflections than for rows which do not. In contrast, the NbL intensity is decreased with respect to the TiK intensity when the crystal is set at symmetry for all types of systematic rows. These observations are interpreted in terms of the influence of atomic number on the sizes of electron shells and hence on their ionization cross-sections. The results are briefly discussed in terms of the technique of ALCHEMI, which is used to determine site occupancy in alloys, and in terms of the quantification of energy dispersive X-ray data from thin samples. (author)

  12. Chameleon induced atomic afterglow

    Energy Technology Data Exchange (ETDEWEB)

    Brax, Philippe [CEA, IPhT, CNRS, Gif-sur-Yvette (France). Inst. de Physique Theorique; Burrage, Clare [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2010-09-15

    The chameleon is a scalar field whose mass depends on the density of its environment. Chameleons are necessarily coupled to matter particles and will excite transitions between atomic energy levels in an analogous manner to photons. When created inside an optical cavity by passing a laser beam through a constant magnetic field, chameleons are trapped between the cavity walls and form a standing wave. This effect will lead to an afterglow phenomenon even when the laser beam and the magnetic field have been turned off, and could be used to probe the interactions of the chameleon field with matter. (orig.)

  13. Interfacing ultracold atoms and mechanical oscillators on an atom chip

    Science.gov (United States)

    Treutlein, Philipp

    2010-03-01

    Ultracold atoms can be trapped and coherently manipulated close to a chip surface using atom chip technology. This opens the exciting possibility of studying interactions between atoms and on-chip solid-state systems such as micro- and nanostructured mechanical oscillators. One goal is to form hybrid quantum systems, in which atoms are used to read out, cool, and coherently manipulate the oscillators' state. In our work, we investigate different coupling mechanisms between ultracold atoms and mechanical oscillators. In a first experiment, we use atom-surface forces to couple the vibrations of a mechanical cantilever to the motion of a Bose-Einstein condensate in a magnetic microtrap on an atom chip. The atoms are trapped at about one micrometer distance from the cantilever surface. We make use of the coupling to read out the cantilever vibrations with the atoms and observe resonant coupling to several well-resolved mechanical modes of the condensate. In a second experiment, we investigate coupling via a 1D optical lattice that is formed by a laser beam retroreflected from a SiN membrane oscillator. The optical lattice serves as a `transfer rod' that couples vibrations of the membrane to the atoms and vice versa. We point out that the strong coupling regime can be reached in coupled atom-oscillator systems by placing both the atoms and the oscillator in a high-finesse optical cavity.

  14. Ion beam steering with a high intensity electron beam

    International Nuclear Information System (INIS)

    In conventional theory, steering or bending an ion beam of high energy and high current requires very intense magnetic fields, which are both uneconomical and bulky. This problem is even more severe for a singly charged ion beam with very high atomic number, which requires large magnetic field energy both to bend and also to focus the beam against its self electric field. In this paper we present a new and simple technique, which will substantially alleviate these problems

  15. Nonlinear beam-beam resonances

    International Nuclear Information System (INIS)

    Head-on collisions of bunched beams are considered, assuming the two colliding beams have opposite charges. A few experimental observations are described. The single resonance analysis is developed that is applicable to the strong-weak case of the beam-beam interaction. In this case, the strong beam is unperturbed by the beam-beam interaction; motions of the weak beam particles are then analyzed in the presence of the nonlinear electromagnetic force produced by the strong beam at the collision points. The coherent motions of the two coupled strong beams are shown to exhibit distinct nonlinear resonance behavior. 16 refs., 22 figs

  16. Effusive atomic oven nozzle design using an aligned microcapillary array

    Energy Technology Data Exchange (ETDEWEB)

    Senaratne, Ruwan, E-mail: rsenarat@physics.ucsb.edu; Rajagopal, Shankari V.; Geiger, Zachary A.; Fujiwara, Kurt M.; Lebedev, Vyacheslav; Weld, David M. [Department of Physics and California Institute for Quantum Emulation, University of California Santa Barbara, Santa Barbara, California 93106 (United States)

    2015-02-15

    We present a simple and inexpensive design for a multichannel effusive oven nozzle which provides improved atomic beam collimation and thus extended oven lifetimes. Using this design, we demonstrate an atomic lithium source suitable for trapped-atom experiments. At a nozzle temperature of 525 °C, the collimated atomic beam flux directly after the nozzle is 1.2 × 10{sup 14} atoms/s with a peak beam intensity greater than 5.0 × 10{sup 16} atoms/s/sr. This suggests an oven lifetime of several decades of continuous operation.

  17. Effusive Atomic Oven Nozzle Design Using a Microcapillary Array

    CERN Document Server

    Senaratne, Ruwan; Geiger, Zachary A; Fujiwara, Kurt M; Lebedev, Vyacheslav; Weld, David M

    2014-01-01

    We present a simple and inexpensive design for a multichannel effusive oven nozzle which provides improved atomic beam collimation and thus extended oven lifetimes. Using this design we demonstrate an atomic lithium source suitable for trapped-atom experiments. At a nozzle temperature of 525$^{\\circ}$C the total atomic beam flux directly after the nozzle is $1.2 \\times 10^{14}$ atoms per second with a peak beam intensity greater than $5.0 \\times 10^{16}$ atoms per second per steradian. This suggests an oven lifetime of several centuries of continuous operation.

  18. Generation of a hollow laser beam by a multimode fiber

    Institute of Scientific and Technical Information of China (English)

    Hongyu Ma; Huadong Cheng; Wenzhuo Zhang; Liang Liu; Yuzhu Wang

    2007-01-01

    A simple method to generate a hollow laser beam by multimode fiber is reported. A dark hollow laser beam is generated from a multimode fiber and the dependence of the output beam profile on the incident angle of laser beam is analyzed. The results show that this hollow laser beam can be used to trap and guide cold atoms.

  19. Candlestick rubidium beam source

    Science.gov (United States)

    Walkiewicz, M. R.; Fox, P. J.; Scholten, R. E.

    2000-09-01

    We describe a long-lived, bright and intense rubidium atomic beam source based on a previously published recirculating candlestick design for sodium, with several modifications and enhancements. The device operates for thousands of hours without maintenance, with brightness of 1.9×1022 m-2 s-1 sr-1.

  20. 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.

  1. 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.

  2. Focusing of particle beams using two-stage laser ablation

    International Nuclear Information System (INIS)

    We report a new technique for producing focused beams of neutrals, ions, and clusters using two-stage laser ablation. We have produced a collimated beam and beams which were focused in one and two dimensions. The on-axis density is 5 x 1015 atoms/cm3 for a barium beam focused in two dimensions over a distance of 10.7 cm. For a collimated beam the density is 1015 atoms/cm3 at the same distance

  3. 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.

  4. Atomic Physics

    CERN Document Server

    Foot, Christopher J

    2007-01-01

    This text will thoroughly update the existing literature on atomic physics. Intended to accompany an advanced undergraduate course in atomic physics, the book will lead the students up to the latest advances and the applications to Bose-Einstein Condensation of atoms, matter-wave inter-ferometry and quantum computing with trapped ions. The elementary atomic physics covered in the early chapters should be accessible to undergraduates when they are first introduced to the subject. To complement. the usual quantum mechanical treatment of atomic structure the book strongly emphasizes the experimen

  5. Atomic polarizabilities

    International Nuclear Information System (INIS)

    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

  6. Ghost Imaging with Atoms

    CERN Document Server

    Khakimov, R I; Shin, D K; Hodgman, S S; Dall, R G; Baldwin, K G H; Truscott, A G

    2016-01-01

    Ghost imaging is a technique -- first realized in quantum optics -- in which the image emerges from cross-correlation between particles in two separate beams. One beam passes through the object to a bucket (single-pixel) detector, while the second beam's spatial profile is measured by a high resolution (multi-pixel) detector but never interacts with the object. Neither detector can reconstruct the image independently. However, until now ghost imaging has only been demonstrated with photons. Here we report the first realisation of ghost imaging of an object using massive particles. In our experiment, the two beams are formed by correlated pairs of ultracold metastable helium atoms, originating from two colliding Bose-Einstein condensates (BECs) via $s$-wave scattering. We use the higher-order Kapitza-Dirac effect to generate the large number of correlated atom pairs required, enabling the creation of a ghost image with good visibility and sub-millimetre resolution. Future extensions could include ghost interfe...

  7. Atom interferometry

    International Nuclear Information System (INIS)

    We will first present a development of the fundamental principles of atom interferometers. Next we will discuss a few of the various methods now available to split and recombine atomic De Broglie waves, with special emphasis on atom interferometers based on optical pulses. We will also be particularly concerned with high precision interferometers with long measurement times such those made with atomic fountains. The application of atom interferometry to the measurement of the acceleration due to gravity will be detailed. We will also develop the atom interferometry based on adiabatic transfer and we will apply it to the measurement of the photon recoil in the case of the Doppler shift of an atomic resonance caused by the momentum recoil from an absorbed photon. Finally the outlook of future developments will be given. (A.C.)

  8. Neutral beams for magnetic fusion

    International Nuclear Information System (INIS)

    Significant advances in forming energetic beams of neutral hydrogen and deuterium atoms have led to a breakthrough in magnetic fusion: neutral beams are now heating plasmas to thermonuclear temperatures, here at LLL and at other laboratories. For example, in our 2XIIB experiment we have injected a 500-A-equivalent current of neutral deuterium atoms at an average energy of 18 keV, producing a dense plasma (1014 particles/cm3) at thermonuclear energy (14 keV or 160 million kelvins). Currently, LLL and LBL are developing beam energies in the 80- to 120-keV range for our upcoming MFTF experiment, for the TFTR tokamak experiment at Princeton, and for the Doublet III tokamak experiment at General Atomic. These results increase our long-range prospects of producing high-intensity beams of energies in the hundreds or even thousands of kilo-electron-volts, providing us with optimistic extrapolations for realizing power-producing fusion reactors

  9. 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 ...

  10. Wave Mechanics of a Two Wire Atomic Beamsplitter

    OpenAIRE

    Bortolotti, Daniele C. E.; Bohn, John L.

    2003-01-01

    We consider the problem of an atomic beam propagating quantum mechanically through an atom beam splitter. Casting the problem in an adiabatic representation (in the spirit of the Born-Oppenheimer approximation in molecular physics) sheds light on explicit effects due to non-adiabatic passage of the atoms through the splitter region. We are thus able to probe the fully three dimensional structure of the beam splitter, gathering quantitative information about mode-mixing, splitting ratios,and r...

  11. Wave Mechanics of a Two Wire Atomic Beamsplitter

    CERN Document Server

    Bortolotti, D C E; Bortolotti, Daniele C. E.; Bohn, John L.

    2004-01-01

    We consider the problem of an atomic beam propagating quantum mechanically through an atom beam splitter. Casting the problem in an adiabatic representation (in the spirit of the Born-Oppenheimer approximation in molecular physics) sheds light on explicit effects due to non-adiabatic passage of the atoms through the splitter region. We are thus able to probe the fully three dimensional structure of the beam splitter, gathering quantitative information about mode-mixing, splitting ratios,and reflection and transmission probabilities.

  12. An atom laser based on Raman transitions

    CERN Document Server

    Moy, G M; Savage, C M

    1996-01-01

    In this paper we present an atom laser scheme using a Raman transition for the output coupling of atoms. A beam of thermal atoms (bosons) in a metastable atomic state |1> are pumped into a multimode atomic cavity. This cavity is coupled through spontaneous emission to a single mode of another cavity for the ground atomic state, |2>. Above a certain threshold pumping rate a large number of atoms, N2, builds up in this single quantum state and transitions to the ground state of the cavity become enhanced by a factor (N2+1). Atoms in this state are then coupled to the outside of the cavity with a Raman transition. This changes the internal state of the atom and imparts a momentum kick, allowing the atoms to leave the system.

  13. Symposium on atomic spectroscopy (SAS-83): abstracts and program

    International Nuclear Information System (INIS)

    Abstracts of papers given at the symposium are presented. Session topics include: Rydbergs, optical radiators, and planetary atoms; highly ionized atoms; ultraviolet radiation; theory, ion traps, and laser cooling; beam foil; and astronomy

  14. Symposium on atomic spectroscopy (SAS-83): abstracts and program

    Energy Technology Data Exchange (ETDEWEB)

    1983-09-01

    Abstracts of papers given at the symposium are presented. Session topics include: Rydbergs, optical radiators, and planetary atoms; highly ionized atoms; ultraviolet radiation; theory, ion traps, and laser cooling; beam foil; and astronomy. (GHT)

  15. On the transverse mode of an atom laser

    OpenAIRE

    Busch, Th.; Köhl, M.; Esslinger, T.; Molmer, K.

    2001-01-01

    The transverse mode of an atom laser beam that is outcoupled from a Bose-Einstein condensate is investigated and is found to be strongly determined by the mean--field interaction of the laser beam with the condensate. Since for repulsive interactions the geometry of the coupling scheme resembles an interferometer in momentum space, the beam is found show filamentation. Observation of this effect would prove the transverse coherence of an atom laser beam.

  16. Quantum noise property in coherent atomic system

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun-xiang; WANG Hai-hong; CAI Jin; GAO Jiang-rui

    2006-01-01

    The coherent superposition of atomic states leads to the characteristic change of interacting lights because of the coupling between the lights and atoms.In this paper,the noise spectrum of the quantified light interacting with the atoms is studied under the condition of electromagnetically induced transparency (EIT).It is shown that the noise spectrum displays a double M-shape noise profile resulted from the conversion of phase noise of probe beam.A squeezing of 0.3 dB can be observed at the detuning of probe light at the proper parameters of atoms and coupling beam.

  17. Slow polaritons with orbital angular momentum in atomic gases

    OpenAIRE

    Ruseckas J.; Mekys A.; Juzeliunas G.

    2011-01-01

    Polariton formalism is applied for studying the propagation of a probe field of light in a cloud of cold atoms influenced by two control laser beams of larger intensity. The laser beams couple resonantly three hyperfine atomic ground states to a common excited state thus forming a tripod configuration of the atomic energy levels involved. The first control beam can have an optical vortex with the intensity of the beam going to zero at the vortex core. The second control beam without a vortex ...

  18. Bessel Beams

    OpenAIRE

    McDonald, Kirk T

    2000-01-01

    Scalar Bessel beams are derived both via the wave equation and via diffraction theory. While such beams have a group velocity that exceeds the speed of light, this is a manifestation of the "scissors paradox" of special relativty. The signal velocity of a modulated Bessel beam is less than the speed of light. Forms of Bessel beams that satisfy Maxwell's equations are also given.

  19. Schroedinger atom

    International Nuclear Information System (INIS)

    Features of an electrodynamical interpretation suggested by Schroedinger for the wave function are discribed. According to this conception electron charges are continuously distributed all over the volume of an atomic system. The proof is given that classical electrodynamics keeps its action inside atom. Schroedinger's atom has been shown to be the only model in which electrones do not lose their energy for emission when they move around nucleus. A significance of the distributed electron charge self-field is estimated. Practical applications of this conception have been noted including the new trend in quantum electrodynamics. Experimental and theoretical corroborations of the atom model with a continuous electron charge are adduced

  20. Development of Atomic Beam Probe for tokamaks

    Czech Academy of Sciences Publication Activity Database

    Berta, M.; Anda, G.; Aradi, M.; Bencze, A.; Buday, Cs.; Kiss, I.G.; Tulipán, Sz.; Veres, G.; Zoletnik, S.; Havlíček, Josef; Háček, Pavel

    2013-01-01

    Roč. 88, č. 11 (2013), s. 2875-2880. ISSN 0920-3796 R&D Projects: GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : ABP * Plasma diagnostics * COMPASS tokamak * Current density * Plasma density profile measurement Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.149, year: 2013 http://www.sciencedirect.com/science/article/pii/S0920379613005048#

  1. Trapping atoms on a transparent permanent-magnet atom chip

    CERN Document Server

    Shevchenko, A; Jaakkola, A; Kaivola, M; Lindvall, T; Pfau, T; Tittonen, I

    2006-01-01

    We describe experiments on trapping of atoms in microscopic magneto-optical traps on an optically transparent permanent-magnet atom chip. The chip is made of magnetically hard ferrite-garnet material deposited on a dielectric substrate. The confining magnetic fields are produced by miniature magnetized patterns recorded in the film by magneto-optical techniques. We trap Rb atoms on these structures by applying three crossed pairs of counter-propagating laser beams in the conventional magneto-optical trapping (MOT) geometry. We demonstrate the flexibility of the concept in creation and in-situ modification of the trapping geometries through several experiments.

  2. Scheme for multistep resonance photoionization of atoms

    Science.gov (United States)

    Liu, Bo; Ning, Xi-Jing

    2001-07-01

    Traditional schemes for multistep resonance photoionization of atoms let every employed laser beam interact with the atoms simultaneously. In such a situation, analyses via time-dependent Schrödinger equation show that high ionization probability requires all the laser beams must be intense enough. In order to decrease laser intensity, we proposed a scheme that the laser beam used to pump the excited atoms (in a higher bound state) into an autoionization state does not interact with the atoms until all the population is transferred by the other lasers from a ground state to the bound state. As an interesting example, we examined three-step photoionization of 235U with our scheme, showing that the intensity of two laser beams can be lowered by two orders of magnitude without losing high ionization probability.

  3. 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.

  4. Quantum Electronics for Atomic Physics

    CERN Document Server

    Nagourney, Warren

    2010-01-01

    Quantum Electronics for Atomic Physics provides a course in quantum electronics for researchers in atomic physics. The book covers the usual topics, such as Gaussian beams, cavities, lasers, nonlinear optics and modulation techniques, but also includes a number of areas not usually found in a textbook on quantum electronics. It includes such practical matters as the enhancement of nonlinear processes in a build-up cavity, impedance matching into a cavity, laser frequencystabilization (including servomechanism theory), astigmatism in ring cavities, and atomic/molecular spectroscopic techniques

  5. Atomic focusing by quantum fields: Entanglement properties

    Energy Technology Data Exchange (ETDEWEB)

    Paz, I.G. da [Departamento de Física, Universidade Federal do Piauí, Campus Ministro Petrônio Portela, CEP 64049-550, Teresina, PI (Brazil); Frazão, H.M. [Universidade Federal do Piauí, Campus Profa. Cinobelina Elvas, CEP 64900-000, Bom Jesus, PI (Brazil); Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Caixa Postal 702, Belo Horizonte, MG 30123-970 (Brazil); Nemes, M.C. [Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Caixa Postal 702, Belo Horizonte, MG 30123-970 (Brazil); Peixoto de Faria, J.G. [Departamento de Física e Matemática, Centro Federal de Educação Tecnológica de Minas Gerais, Av. Amazonas 7675, Belo Horizonte, MG 30510-000 (Brazil)

    2014-04-01

    The coherent manipulation of the atomic matter waves is of great interest both in science and technology. In order to study how an atom optic device alters the coherence of an atomic beam, we consider the quantum lens proposed by Averbukh et al. [1] to show the discrete nature of the electromagnetic field. We extend the analysis of this quantum lens to the study of another essentially quantum property present in the focusing process, i.e., the atom–field entanglement, and show how the initial atomic coherence and purity are affected by the entanglement. The dynamics of this process is obtained in closed form. We calculate the beam quality factor and the trace of the square of the reduced density matrix as a function of the average photon number in order to analyze the coherence and purity of the atomic beam during the focusing process.

  6. Atomic focusing by quantum fields: Entanglement properties

    International Nuclear Information System (INIS)

    The coherent manipulation of the atomic matter waves is of great interest both in science and technology. In order to study how an atom optic device alters the coherence of an atomic beam, we consider the quantum lens proposed by Averbukh et al. [1] to show the discrete nature of the electromagnetic field. We extend the analysis of this quantum lens to the study of another essentially quantum property present in the focusing process, i.e., the atom–field entanglement, and show how the initial atomic coherence and purity are affected by the entanglement. The dynamics of this process is obtained in closed form. We calculate the beam quality factor and the trace of the square of the reduced density matrix as a function of the average photon number in order to analyze the coherence and purity of the atomic beam during the focusing process.

  7. Cold atom dynamics in linear and nonlinear optical potentials

    Science.gov (United States)

    Williams, William

    This dissertation has two major components. The first is theoretical work on using multiple optical fields to control atoms. Theoretical models for creating complex optical potentials for use in atomic lithography are explored and a proposal for serial writing of an atomic beam is presented. A proposal to compress a cloud of cold atoms to create a tightly confined cigar shaped cloud of dense atoms for use in atom optics experiments and quantum control is also presented. The second component focuses on the study of nonlinear self-focusing in cold Cesium atoms. Modulation instability is explored in a cold atom environment which produces novel effects such as red detuned modulational instability. Several experimental setups are explored and compared with theoretical models. The first is two-wave mixing which consists of a strong pump beam and a weak probe beam crossing in a MOT. The second is using a counter-propagating pump beam to balance the radiation force of the forward propagating pump beam. The third is retro-reflecting both the probe and the pump beam which creates a more complicated experimental setup with multiple atomic gratings. Energy transfer from the pump to the probe beam via atomic density redistribution for red detuning is presented.

  8. Study on the fine control of atoms by coherent interaction

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jae Min; Rho, S. P.; Park, H. M.; Lee, K. S.; Rhee, Y. J.; Yi, J. H.; Jeong, D. Y.; Jung, E. C.; Choe, A. S.; Lee, J. M

    1998-01-01

    The basic research on the control of atoms using the coherent interaction, such as the development of the generator of the thermal atomic beam with high directionality, the photodeflection of atomic beam and the coherent excitation of atoms, has been performed. Yb atomic beam with small divergence was generated and the deflection mechanism of the atomic beam was studied by using a broad band dye laser and a narrow band laser. It has been proved that the single mode dye laser with narrow bandwidth was suitable for deflection of atoms but the frequency locking system was indispensable. And the apparatus for intermodulated optogalvanic (IMOG) experiment was developed and the high resolution optogalvanic spectroscopy was studied for laser frequency stabilization. (author). 74 refs., 1 tab., 26 figs

  9. Atom chip gravimeter

    Science.gov (United States)

    Schubert, Christian; Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Ahlers, Holger; Müntinga, Hauke; Matthias, Jonas; Sahelgozin, Maral; Herr, Waldemar; Lämmerzahl, Claus; Ertmer, Wolfgang; Rasel, Ernst

    2016-04-01

    1552-1557 (QUANTUS-IV-Fallturm) and by the Deutsche Forschungsgemeinschaft in the framework of the SFB 1128 geo-Q. [1] P. Berg et al., Composite-Light-Pulse Technique for High-Precision Atom Interferometry, Phys. Rev. Lett., 114, 063002, 2015. [2] A. Peters et al., Measurement of gravitational acceleration by dropping atoms, Nature 400, 849, 1999. [3] D. Schlippert et al., Quantum Test of the Universality of Free Fall, Phys. Rev. Lett., 112, 203002, 2014. [4] A. Louchet-Chauvet et al., The influence of transverse motion within an atomic gravimeter, New J. Phys. 13, 065026, 2011. [5] Q. Bodart et al., A cold atom pyramidal gravimeter with a single laser beam, Appl. Phys. Lett. 96, 134101, 2010. [6] H. Müntinga et al., Interferometry with Bose-Einstein Condensates in Microgravity, Phys. Rev. Lett., 110, 093602, 2013. [7] T. Kovachy et al., Matter Wave Lensing to Picokelvin Temperatures, Phys. Rev. Lett. 114, 143004, 2015. [8] J. Rudolph et al., A high-flux BEC source for mobile atom interferometers, New J. Phys. 17, 065001, 2015.

  10. Historical Account And Branching To Rarefied Gas Dynamics Of Atomic and Molecular Beams : A Continuing And Fascinating Odyssey Commemorated By Nobel Prizes Awarded To 23 Laureates In Physics And Chemistry

    Science.gov (United States)

    Campargue, Roger

    2005-05-01

    This Historical Account derived in part from D. R. Herschbach was presented as an opening lecture of the Molecular Beam Session organized at the 24th International Symposium on Rarefied Gas Dynamics held in Bari, Italy, in July 2004. The emphasis is on the impressive results due to the molecular beam techniques in the last century. The first section summarizes the historical beam experiments performed by 14 Nobel Prize laureates having used the thermally effusive sources to establish the basic principles of Modern Physics. The second section is on the branching of Molecular Beams to Rarefied Gas Dynamics having permitted to investigate the physics of supersonic free jets and transform the molecular beam techniques. Finally, the last section relates the spectacular molecular beam experiments in helium free jet ultracooling, molecular spectroscopy, chemical reaction dynamics, clustering and modification of low density matter, and biomolecule mass spectrometry, rewarded by nine Nobel Prizes in Chemistry from 1986 to 2002.

  11. Technological innovation of quantum beams

    International Nuclear Information System (INIS)

    To celebrate the centennial anniversary of Einstein's great achievement done in 1905, 'World Year of Physics 2005 Forum,' Japan, held a conference on May 25, 2005, in Tokyo for students called 'Quantum Beam Technology Innovation.' This report consists of Proceeding of the lectures given at the conference which includes the new world to be exploited by quantum beam technology, Japanese science and technology policy in 21st century, expectation from research and development of company, quantum beam facilities and advanced research programs, nanotechnology and material science, utility of physical tools in life science fields, and quantum beam technology applied to industry. Topics are the nature of material wave and the coherency which explore the fine structure of matter, atomic lasers, Spring-8 facility at Harima, intense neutron beams at JAEA, RI beams at RIKEN, B factory of KEK, and HIMAC at Chiba for medical uses. (S. Ohno)

  12. Positronium atom coherent photoproduction in crystal

    International Nuclear Information System (INIS)

    Coherent production of relativistic positronium atom by a high energy photon under the axial orientation is considered. The consideration is based on the interactions with a separate axis, i.e. with the chain of N atoms. In this case the cross section positronium atom production is formed by summation of production amplitudes on N atoms, calculation of modulus square of complete amplitude and summation by all photon states of a crystal. It is shown that application of photon beams of accelerators can serve as an effective method for positronium atom generation

  13. Relativistic atomic physics at the SSC

    International Nuclear Information System (INIS)

    This report discusses the following proposed work for relativistic atomic physics at the Superconducting Super Collider: Beam diagnostics; atomic physics research; staffing; education; budget information; statement concerning matching funds; description and justification of major items of equipment; statement of current and pending support; and assurance of compliance

  14. Quantum State Reconstruction Using Atom Optics

    OpenAIRE

    Varcoe, B. T. H.; Sang, R. T.; MacGillivray, W. R.; Stadage, M C

    1999-01-01

    We present a novel technique in which the total internal quantum state of an atom may be reconstructed via the measurement of the momentum transferred to an atom following its interaction with a near resonant travelling wave laser beam. We present the first such measurement and demonstrate the feasibility of the technique.

  15. Neutral particle beam sensing and steering

    International Nuclear Information System (INIS)

    The direction of a neutral particle beam (NPB) is determined by detecting Lya radiation emitted during motional quenching of excited H(2S) atoms in the beam during movement of the atoms through a magnetic exit to define an optical axis that intercepts the beam at a viewing angle to include a volume generating a selected number of photons for detection. The detection system includes a lens having an area that is small relative to the NPB area and a pixel array located in the focal plane of the lens. The lens viewing angle and area pixel array are selected to optimize the beam tilt sensitivity. In one embodiment two detectors are placed coplanar with the beam axis to generate a difference signal that is insensitive to beam variations, other than beam tilt

  16. Precision Excited State Lifetime Measurements for Atomic Parity Violation and Atomic Clocks

    Science.gov (United States)

    Sell, Jerry; Patterson, Brian; Gearba, Alina; Snell, Jeremy; Knize, Randy

    2016-05-01

    Measurements of excited state atomic lifetimes provide a valuable test of atomic theory, allowing comparisons between experimental and theoretical transition dipole matrix elements. Such tests are important in Rb and Cs, where atomic parity violating experiments have been performed or proposed, and where atomic structure calculations are required to properly interpret the parity violating effect. In optical lattice clocks, precision lifetime measurements can aid in reducing the uncertainty of frequency shifts due to the surrounding blackbody radiation field. We will present our technique for precisely measuring excited state lifetimes which employs mode-locked ultrafast lasers interacting with two counter-propagating atomic beams. This method allows the timing in the experiment to be based on the inherent timing stability of mode-locked lasers, while counter-propagating atomic beams provides cancellation of systematic errors due to atomic motion to first order. Our current progress measuring Rb excited state lifetimes will be presented along with future planned measurements in Yb.

  17. Intense positron beams: linacs - preworkshop copy

    International Nuclear Information System (INIS)

    Beams of monoenergetic positrons with energies of a few eV to many keV have been used in experiments in atomic physics, solid-state physics and materials science. The production of positron beams from a new source, an electron linac, is described. Intense, pulsed beams of low-energy positrons have been produced by a high-energy beam from an electron linac. The production efficiency, moderator geometry, beam spot size and other positron beam parameters have been determined for electrons with energies from 60 to 120 MeV. Low-energy positron beams produced with a high-energy electron linac can be of much higher intensity than those beams currently derived from radioactive sources. These higher-intensity beams will make possible positron experiments previously infeasible

  18. Intense positron beams: linacs. Preworkshop copy

    International Nuclear Information System (INIS)

    Beams of monoenergetic positrons with energies of a few eV to many keV have been used in experiments in atomic physics, solid state physics and materials science. The production of positron beams from a new source, an electron linac, is described. Intense, pulsed beams of low-energy positrons have been produced by a high-energy beam from an electron linac. The production efficiency, moderator geometry, beam spot size and other positron beam parameters have been determined for electrons with energies from 60 to 120 MeV. Low-energy positron beams produced with a high-energy electron linac can be of much higher intensity than those beams currently derived from radioactive sources. These higher intensity beams will make possible positron experiments previously infeasible

  19. Atomic secrecy

    International Nuclear Information System (INIS)

    An article, The H-Bomb Secret: How We Got It, Why We're Telling It, by Howard Morland was to be published in The Progressive magazine in February, 1979. The government, after learning of the author's and the editors' intention to publish the article and failing to persuade them to voluntarily delete about 20% of the text and all of the diagrams showing how an H-bomb works, requested a court injunction against publication. Acting under the Atomic Energy Act of 1954, US District Court Judge Robert W. Warren granted the government's request on March 26. Events dealing with the case are discussed in this publication. Section 1, Progressive Hydrogen Bomb Case, is discussed under the following: Court Order Blocking Magazine Report; Origins of the Howard Morland Article; Author's Motives, Defense of Publication; and Government Arguments Against Disclosure. Section 2, Access to Atomic Data Since 1939, contains information on need for secrecy during World War II; 1946 Atomic Energy Act and its effects; Soviet A-Bomb and the US H-Bomb; and consequences of 1954 Atomic Energy Act. Section 3, Disputed Need for Atomic Secrecy, contains papers entitled: Lack of Studies on H-Bomb Proliferation; Administration's Position on H-Bombs; and National Security Needs vs Free Press

  20. Atomic interference patterns in the transverse plane

    Science.gov (United States)

    Boustimi, M.; Bocvarski, V.; de Lesegno, B. Viaris; Brodsky, K.; Perales, F.; Baudon, J.; Robert, J.

    2000-03-01

    A quadrupolar static magnetic field used as a phase object in a Stern-Gerlach atom interferometer produces phase shifts proportional to the distance to the zero-field line. As a consequence the transverse intensity profile of the atomic beam beyond the interferometer is modulated by an interference pattern which is a ``phase portrait'' of the field configuration. This pattern-a central bright spot surrounded by annular fringes-can be translated as a whole in any transverse direction by adding a homogeneous field to the quadrupolar field. These effects have been investigated experimentally with a beam of metastable hydrogen atoms H*(2s), either by measuring the atom flux through a fixed slit or by scanning the beam profile through a movable hole. The results are in good agreement with the theoretical predictions.

  1. Compact electron-beam source for formation of neutral beams of very low vapor pressure materials

    International Nuclear Information System (INIS)

    An electron-beam heater and associated power supply have been developed for use in formation of metal vapors for neutral beam studies. The device is small with relatively low power (250 W). It is easily constructed and designed such that the target surface is normal to the direction of propagation of the neutral beam. Beams of tantalum atoms and carbon particles have been formed using the device

  2. Compact electron-beam source for formation of neutral beams of very low vapor pressure materials

    Energy Technology Data Exchange (ETDEWEB)

    Rutherford, J.A.; Vroom, D.A.

    1978-07-01

    An electron-beam heater and associated power supply have been developed for use in formation of metal vapors for neutral beam studies. The device is small with relatively low power (250 W). It is easily constructed and designed such that the target surface is normal to the direction of propagation of the neutral beam. Beams of tantalum atoms and carbon particles have been formed using the device.

  3. 14th international symposium on molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    This report discusses research being conducted with molecular beams. The general topic areas are as follows: Clusters I; reaction dynamics; atomic and molecular spectroscopy; clusters II; new techniques; photodissociation dynamics; and surfaces.

  4. 14th international symposium on molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    1992-09-01

    This report discusses research being conducted with molecular beams. The general topic areas are as follows: Clusters I; reaction dynamics; atomic and molecular spectroscopy; clusters II; new techniques; photodissociation & dynamics; and surfaces.

  5. 14th international symposium on molecular beams

    International Nuclear Information System (INIS)

    This report discusses research being conducted with molecular beams. The general topic areas are as follows: Clusters I; reaction dynamics; atomic and molecular spectroscopy; clusters II; new techniques; photodissociation ampersand dynamics; and surfaces

  6. Beam - cavity interaction beam loading

    International Nuclear Information System (INIS)

    The interaction of a beam with a cavity and a generator in cyclic accelerators or storage rings is investigated. Application of Maxwell's equations together with the nonuniform boundary condition allows one to get an equivalent circuit for a beam-loaded cavity. The general equation for beam loading is obtained on the basis of the equivalent circuit, and the beam admittance is calculated. Formulas for power consumption by a beam-loaded cavity are derived, and the optimal tuning and coupling factor are analyzed. (author)

  7. Innovation and optimization of a method of pump-probe polarimetry with pulsed laser beams in view of a precise measurement of parity violation in atomic cesium; Innovation et optimisation d'une methode de polarimetrie pompe-sonde avec des faisceaux laser impulsionnels en vue d'une mesure precise de violation de la parite dans l'atome de cesium

    Energy Technology Data Exchange (ETDEWEB)

    Chauvat, D

    1997-10-15

    While Parity Violation (PV) experiments on highly forbidden transitions have been using detection of fluorescence signals; our experiment uses a pump-probe scheme to detect the PV signal directly on a transmitted probe beam. A pulsed laser beam of linear polarisation {epsilon}{sub 1} excites the atoms on the 6S-7S cesium transition in a colinear electric field E || k(ex). The probe beam (k(pr) || k(ex)) of linear polarisation {epsilon}{sub 2} tuned to the transition 7S-6P(3/2) is amplified. The small asymmetry ({approx} 10{sup -6}) in the gain that depends on the handedness of the tri-hedron (E, {epsilon}{sub 1}, {epsilon}{sub 2}) is the manifestation of the PV effect. This is measured as an E-odd apparent rotation of the plane of polarization of the probe beam; using balanced mode polarimetry. New criteria of selection have been devised, that allow us to distinguish the true PV-signal against fake rotations due to electromagnetic interferences, geometrical effects, polarization imperfections, or stray transverse electric and magnetic fields. These selection criteria exploit the symmetry of the PV-rotation - linear dichroism - and the revolution symmetry of the experiment. Using these criteria it is not only possible to reject fake signals, but also to elucidate the underlying physical mechanisms and to measure the relevant defects of the apparatus. The present signal-to-noise ratio allows embarking in PV measurements to reach the 10% statistical accuracy. A 1% measurement still requires improvements. Two methods have been demonstrated. The first one exploits the amplification of the asymmetry at high gain - one major advantage provided by our detection method based on stimulated emission. The second method uses both a much higher incident intensity and a special dichroic component which magnifies tiny polarization rotations. (author)

  8. 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.

  9. 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

  10. Diffraction of fast metastable atoms by micrometric reflection gratings

    Science.gov (United States)

    Grucker, J.; Karam, J.-C.; Correia, F.; Perales, F.; Vassilev, G.; Bocvarski, V.; Chérif, S. M.; Baudon, J.; Ducloy, M.

    2007-03-01

    Diffraction of thermal velocity metastable atoms by non-magnetic and magnetic reflection gratings of micrometric period has been observed. This observation is made possible by the use of an ultra narrow beam generated by metastability exchange. Grazing incidence angles are exploited to minimise the quenching of metastable atoms on the grating surface. Potential applications are beam splitting, atom holography and probing of micro-sized solid surfaces.

  11. Atoms as Qed bound atoms

    International Nuclear Information System (INIS)

    The relevance of Quantum Electrodynamics (Qed) in contemporary atomic structure theory is reviewed. Recent experimental advances allow both the production of heavy ions of high charge as well as the measurement of atomic properties with a precision never achieved before. The description of heavy atoms with few electrons via the successive incorporation of one, two, etcetera photons in a rigorous manner and within the bound state Furry representation of Qed is technically feasible. For many-electron atoms the many-body (correlation) effects are very important and it is practically impossible to evaluate all the relevant Feynman diagrams to the required accuracy. Thus, it is necessary to develop a theoretical scheme in which the radiative and nonradiative effects are taken into account in an effective way making emphasis in electronic correlation. Preserving gauge invariance, and avoiding both continuum dissolution and variational collapse are basic problems that must be solved when using effective potential methods and finite-basis representations of them. In this context, we shall discuss advances and problems in the description of atoms as Qed bound states. (Author)

  12. Intense low energy positron beams

    Energy Technology Data Exchange (ETDEWEB)

    Lynn, K.G.; Jacobsen, F.M.

    1993-12-31

    Intense positron beams are under development or being considered at several laboratories. Already today a few accelerator based high intensity, low brightness e{sup +} beams exist producing of the order of 10{sup 8} {minus} 10{sup 9} e{sup +}/sec. Several laboratories are aiming at high intensity, high brightness e{sup +} beams with intensities greater than 10{sup 9} e{sup +}/sec and current densities of the order of 10{sup 13} {minus} 10{sup 14} e{sup +} sec{sup {minus}} {sup 1}cm{sup {minus}2}. Intense e{sup +} beams can be realized in two ways (or in a combination thereof) either through a development of more efficient B{sup +} moderators or by increasing the available activity of B{sup +} particles. In this review we shall mainly concentrate on the latter approach. In atomic physics the main trust for these developments is to be able to measure differential and high energy cross-sections in e{sup +} collisions with atoms and molecules. Within solid state physics high intensity, high brightness e{sup +} beams are in demand in areas such as the re-emission e{sup +} microscope, two dimensional angular correlation of annihilation radiation, low energy e{sup +} diffraction and other fields. Intense e{sup +} beams are also important for the development of positronium beams, as well as exotic experiments such as Bose condensation and Ps liquid studies.

  13. Frozen Beams

    CERN Document Server

    Okamoto, Hiromi

    2005-01-01

    In general, the temperature of a charged particle beam traveling in an accelerator is very high. Seen from the rest frame of the beam, individual particles randomly oscillate about the reference orbit at high speed. This internal kinetic energy can, however, be removed by introducing dissipative interactions into the system. As a dissipative process advances, the beam becomes denser in phase space or, in other words, the emittance is more diminished. Ideally, it is possible to reach a "zero-emittance" state where the beam is Coulomb crystallized. The space-charge repulsion of a crystalline beam just balances the external restoring force provided by artificial electromagnetic elements. In this talk, general discussion is made of coasting and bunched crystalline beams circulating in a storage ring. Results of molecular dynamics simulations are presented to demonstrate the dynamic nature of various crystalline states. A possible method to approach such an ultimate state of matter is also discussed.

  14. Uncertainty of cesium-beam time standards due to beam asymmetry

    Science.gov (United States)

    Becker, G.

    1980-12-01

    As a consequence of the spatial phase distribution in the resonators of cesium-beam time and frequency standards, the generated frequency depends on the specific path of the atomic beam. A change of the position of the atomic beam source may result in a beam displacement normal to the beam direction. For a deflection system consisting of a combination of quadrupole and hexapole magnets for two-dimensional beam deflection, the displacement of the center of mass of the beam resulting from a misalignment of the beam source is computed. To this end, the distribution of the beam intensity on the collector is first determined. It is shown that for the cesium-beam time and frequency standard CS1 of the Physikalisch-Technische Bundesanstalt (PTB), the uncertainty of the position of the center of mass of the beam entails a contribution to the uncertainty of the standard of less than 1 x 10 to the -15th. The amount of the displacement of the center of mass of the beam can be determined from the decrease of the beam flux on the collector caused by an adjustment of the beam source.

  15. Large-angle beam deflection of a laser-cooled sodium beam

    International Nuclear Information System (INIS)

    A sodium atomic beam has been decelerated and laser cooled to a longitudinal beam temperature of less than 30 mK. Subsequently these slow atoms with a typical velocity of 100 m/sec were selectively deflected by laser-light forces. The deflection angle was typically 30 degree. The deflection scheme permits a stabilization of the transverse velocities in the deflected atomic beam down to the quantum-limit temperature for one dimension (0.7x240 μK). The experimentally achieved temperatures are of the order of 1 mK

  16. Beam loading

    CERN Document Server

    Gamp, Alexander

    2013-01-01

    We begin by giving a description of the radio-frequency generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, radio-frequency feedback and feedforward are described. Examples of digital radio-frequency phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.

  17. Cold Atom Source Containing Multiple Magneto-Optical Traps

    Science.gov (United States)

    Ramirez-Serrano, Jaime; Kohel, James; Kellogg, James; Lim, Lawrence; Yu, Nan; Maleki, Lute

    2007-01-01

    An apparatus that serves as a source of a cold beam of atoms contains multiple two-dimensional (2D) magneto-optical traps (MOTs). (Cold beams of atoms are used in atomic clocks and in diverse scientific experiments and applications.) The multiple-2D-MOT design of this cold atom source stands in contrast to single-2D-MOT designs of prior cold atom sources of the same type. The advantages afforded by the present design are that this apparatus is smaller than prior designs.

  18. Hybrid atom-membrane optomechanics

    Directory of Open Access Journals (Sweden)

    Korppi Maria

    2013-08-01

    Full Text Available We report on the realization of a hybrid optomechanical system in which ultracold atoms are coupled to a micromechanical membrane. The atoms are trapped in the intensity maxima of an optical standing wave formed by retroreflection of a laser beam from the membrane surface. Vibrations of the membrane displace the standing wave, thus coupling to the center-of-mass motion of the atomic ensemble. Conversely, atoms imprint their motion onto the laser light, thereby modulating the radiation pressure force on the membrane. In this way, the laser light mediates a long-distance coherent coupling between the two systems. When the trap frequency of the atoms is matched to the membrane frequency, we observe resonant energy transfer. Moreover, we demonstrate sympathetic damping of the membrane motion by coupling it to laser-cooled atoms. Theoretical investigations show that the coupling strength can be considerably enhanced by placing the membrane inside an optical cavity. This could lead to quantum coherent coupling and ground-state cooling of the membrane via a distant atomic ensemble.

  19. 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.

  20. Production of hyperthermal hydrogen atoms by an arc discharge

    International Nuclear Information System (INIS)

    A magnetically confined thermal electric arc gas heater has been designed and built as a suitable source of heat for dissociating hydrogen molecules with energy in the range of a few eV. Specifically, the average beam kinetic energy is determined to be 1.5 eV, the dissociation rate is 0.5 atoms per molecule and the atom beam intensity in the forward direction is 1018 atoms/sr-sec. The working pressure in the arc discharge region is from 15 to 25 torr. This novel atom source has been successfully ignited and operated with pure hydrogen during several hours of continuous performance, maintaining its characteristics. The hyperthermal hydrogen atom beam, which is obtained from this source is analyzed and characterized in a high vacuum system, the characterization of the atom beam is accomplished by two different methods: calorimetry and surface ionization. Calorimetic sensor were used for detecting the atom beam by measuring the delivered power of the impinging atoms on the sensor surface. In the second approach an H-surface production backscattering experiment from a low work function surface was conducted. The validity of these two methods is discussed, and the results are compared. The different collision mechanisms to dissociate and ionize hydrogen molecules in the arch discharge are reviewed, as well as the physics of electric arcs. Finally, a Monte Carlo simulation program is used to calculate the ionization probability of low energy atoms perpendicularly reflected from a surface converter, as a model for atom surface ionization

  1. Creation of matter wave Bessel beams

    OpenAIRE

    Ryu, C.; Henderson, K. C.; Boshier, M. G.

    2013-01-01

    Bessel beams are plane waves with amplitude profiles described by Bessel functions. They are important because of their property of limited diffraction and their capacity to carry orbital angular momentum. Here we report the creation of a Bessel beam of de Broglie matter waves. The Bessel beam is produced by the free evolution of a thin toroidal atomic Bose-Einstein condensate (BEC) which has been set into rotational motion. By attempting to stir it at different rotation rates, we show that t...

  2. Radiative lifetimes and atomic transition probabilities

    International Nuclear Information System (INIS)

    Radiative lifetimes and atomic transition probabilities have been measured for over 35 neutral and singly ionized species in the Wisconsin Atomic Transition Probabilities (WATP) Program since it began in 1980. Radiative lifetimes are measured using time-resolved laser-induced fluorescence of a slow atomic/ionic beam. These lifetimes are combined with branching fractions to yield absolute atomic transition probabilities for neutral and singly ionized species. The branching fractions are determined from emission spectra recorded using the 1.0 m Fourier-transform spectrometer at the National Solar Observatory. The current focus of the WATP Program is on the rare-earth elements, in particular Tm, Dy, and Ho

  3. Beam Instabilities

    CERN Document Server

    Rumolo, G

    2014-01-01

    When a beam propagates in an accelerator, it interacts with both the external fields and the self-generated electromagnetic fields. If the latter are strong enough, the interplay between them and a perturbation in the beam distribution function can lead to an enhancement of the initial perturbation, resulting in what we call a beam instability. This unstable motion can be controlled with a feedback system, if available, or it grows, causing beam degradation and loss. Beam instabilities in particle accelerators have been studied and analysed in detail since the late 1950s. The subject owes its relevance to the fact that the onset of instabilities usually determines the performance of an accelerator. Understanding and suppressing the underlying sources and mechanisms is therefore the key to overcoming intensity limitations, thereby pushing forward the performance reach of a machine.

  4. An optically-guided atomic fountain

    International Nuclear Information System (INIS)

    We have performed the experiment of optically guided atomic fountain by using a cylindrical hollow laser beam (HLB). Cold atoms after polarization-gradient cooling (PGC) are launched upward in a rather simple way by just varying rapidly the current of vertical directional Helmholz coils, so that the frequency difference between the upgoing and the downgoing cooling laser can be obtained due to the atomic Zeeman shift. The entire process is equivalent to the moving molasses scheme, and consequently atoms are cooled down below the Doppler limit. We observe that 0.5% of the launched atoms are detected without the HLB, whereas tenfold enhancement of the HLB-guided atomic fountain is clearly obtained without appreciable broadening of the time of flight (TOF) signal. We have demonstrated tenfold enhancement of the atomic funneling efficiency for the HLB-guided atomic fountain which may lead to the improved performance of atom optical experiments based on atomic fountain such as Rb atomic clock. Moreover, if two ground-state hyperfine levels experience the similar light shifts at the appropriate detuning, it may be also useful to apply to Rb atomic fountain clock

  5. Single atom detection of calcium isotopes by atom trap trace analysis

    CERN Document Server

    Hoekstra, S; Morgenstern, R; Wilschut, H W; Hoekstra, R

    2005-01-01

    We demonstrate a combination of an isotopically purified atom beam and a magneto-optical trap which enables the single atom detection of all stable isotopes of calcium (40, 42, 43, 44, 46 and 48). These isotopes range in abundance from 96.9 % (40Ca) to 0.004 (46Ca). The trap is loaded from an atomic beam which is decelerated in a Zeeman slower and subsequently deflected over an angle of 30 degrees by optical molasses. The isotope selectivity of the Zeeman slower and the deflection stage is investigated experimentally and compared with Monte Carlo simulations.

  6. Gravitational decoherence of atomic interferometers

    OpenAIRE

    Lamine, Brahim; Jaekel, Marc-Thierry; Reynaud, Serge

    2002-01-01

    We study the decoherence of atomic interferometers due to the scattering of stochastic gravitational waves. We evaluate the `direct' gravitational effect registered by the phase of the matter waves as well as the `indirect' effect registered by the light waves used as beam-splitters and mirrors for the matter waves. Considering as an example the space project HYPER, we show that both effects are negligible for the presently studied interferometers.

  7. Active Beam Spectroscopy

    Science.gov (United States)

    von Hellermann, M. G.; Delabie, E.; Jaspers, R. J. E.; Biel, W.; Marchuk, O.; Summers, H. P.; Whiteford, A.; Giroud, C.; Hawkes, N. C.; Zastrow, K. D.

    2008-03-01

    Charge eXchange Recombination Spectroscopy (CXRS) plays a pivotal role in the diagnostics of hot fusion plasmas and is implemented currently in most of the operating devices. In the present report the main features of CXRS are summarized and supporting software packages encompassing "Spectral Analysis Code CXSFIT", "Charge Exchange Analysis Package CHEAP", and finally "Forward Prediction of Spectral Features" are described. Beam Emission Spectroscopy (BES) is proposed as indispensable cross-calibration tool for absolute local impurity density measurements and also for the continuous monitoring of the neutral beam power deposition profile. Finally, a full exploitation of the `Motional Stark Effect' pattern is proposed to deduce local pitch angles, total magnetic fields and possibly radial electric fields. For the proposed active beam spectroscopy diagnostic on ITER comprehensive performance studies have been carried out. Estimates of expected spectral signal-to-noise ratios are based on atomic modelling of neutral beam stopping and emissivities for CXRS, BES and background continuum radiation as well as extrapolations from present CXRS diagnostic systems on JET, Tore Supra, TEXTOR and ASDEX-UG. Supplementary to thermal features a further promising application of CXRS has been proposed recently for ITER, that is a study of slowing-down alpha particles in the energy range up to 2 MeV making use of the 100 keV/amu DNB (Diagnostic Neutral Beam) and the 500 keV/amu HNB (Heating Neutral Beam). Synthetic Fast Ion Slowing-Down spectra are evaluated in terms of source rates and slowing-down parameters

  8. Neutral atom lithography with metastable helium

    Science.gov (United States)

    Allred, Claire Shean

    In this dissertation we describe our performance of resist assisted neutral atom lithography using a bright beam of metastable 23S1 Helium (He*). Metastable Helium atoms have 20 eV of internal energy making them easy to detect and able to destroy a resist. The He* is produced by a reverse flow DC discharge source and then collimated with the bichromatic force, followed by three optical molasses velocity compression stages. The atoms in the resulting beam have a mean longitudinal velocity of 1125 m/s and a divergence of 1.1 mrad. The typical beam flux is 2 x 109 atoms/mm2s through a 0.1mm diameter aperture 70 cm away from the source. The internal energy of the atoms damages the molecules of a self assembled monolayer (SAM) of nonanethiol. The undisturbed SAM protects a 200 A layer of gold that has been evaporated onto a prepared Silicon wafer from a wet chemical etch. Two methods are used to pattern the He* atoms before they destroy the SAM. First, a Nickel micro mesh was used to protect the SAM. These experiments established an appropriate dosage and etch time for patterning. The samples were analyzed with an atomic force microscope and found to have an edge resolution of 63 nm. Then, patterning was accomplished using the dipole force the atoms experience while traversing a standing wave of lambda = 1083nm light tuned 500MHz below the 23S 1 → 23P2 transition. Depending on the intensity of the light, the He* atoms are focused or channeled into lines separated by lambda/2. The lines cover the entire exposed length of the substrate, about 3 mm. They are about 3 mm long, corresponding to about twice the beam waist of the laser standing wave. Thus there are 6 x 10 3 lines of length 5500lambda. These results agree with our numerical simulations of the experiment.

  9. Electron beam coherence measurements using diffracted beam interferometry/holography.

    Science.gov (United States)

    Herring, Rodney A

    2009-06-01

    The intensity and coherence of elastically and inelastically scattered electrons have been studied by the interference of electron-diffracted beams using a method of diffracted beam interferometry/holography (DBI/H). In the interferograms produced, fringes were found to exist from low to high scattering angles. The intensity and coherence of the fringes are useful for understanding the contrast mismatch between experimental and simulated images found in atomic resolution images of crystals produced by transmission electron microscopy (TEM) and annular dark-field (ADF) scanning transmission electron microscopy (STEM). The fringes disappear when the interfering beams are separated from an exact overlay position, which produces a measurement of the beam's lateral coherence and holds promise for measuring the coherence of the respective quasi-particles associated with the energy loss electrons. PMID:19141592

  10. Exotic atoms

    International Nuclear Information System (INIS)

    The experiments use a solid hydrogen layer to form muonic hydrogen isotopes that escape into vacuum. The method relies on transfer of the muon from protium to either a deuteron or a triton. The resulting muonic deuterium or muonic tritium will not immediately thermalize because of the very low elastic cross sections, and may be emitted from the surface of the layer. Measurements which detect decay electrons, muonic x-rays, and fusion products have been used to study the processes. A target has been constructed which exploits muonic atom emission in order to learn more about the energy dependence of transfer and muon molecular formation

  11. Atomic Clocks

    Science.gov (United States)

    Wynands, Robert

    Time is a strange thing. On the one hand it is arguably the most inaccessible physical phenomenon of all: both in that it is impossible to manipulate or modify—for all we know—and in that even after thousands of years mankind's philosophers still have not found a fully satisfying way to understand it. On the other hand, no other quantity can be measured with greater precision. Today's atomic clocks allow us to reproduce the length of the second as the SI unit of time with an uncertainty of a few parts in 1016—orders of magnitude better than any other quantity. In a sense, one can say [1

  12. Tightly confined atoms in optical dipole traps

    International Nuclear Information System (INIS)

    This thesis reports on the design and setup of a new atom trap apparatus, which is developed to confine few rubidium atoms in ultrahigh vacuum and make them available for controlled manipulations. To maintain low background pressure, atoms of a vapour cell are transferred into a cold atomic beam by laser cooling techniques, and accumulated by a magneto-optic trap (MOT) in a separate part of the vacuum system. The laser cooled atoms are then transferred into dipole traps made of focused far-off-resonant laser fields in single- or crossed-beam geometry, which are superimposed with the center of the MOT. Gaussian as well as hollow Laguerre-Gaussian (LG$(01)$) beam profiles are used with red-detuned or blue-detuned light, respectively. Microfabricated dielectric phase objects allow efficient and robust mode conversion of Gaussian into Laguerre-Gaussian laser beams. Trap geometries can easily be changed due to the highly flexible experimental setup. The dipole trap laser beams are focused to below 10 microns at a power of several hundred milliwatts. Typical trap parameters, at a detuning of several ten nanometers from the atomic resonance, are trag depths of few millikelvin, trap frequencies near 30-kHz, trap light scattering rates of few hundred photons per atom and second, and lifetimes of several seconds. The number of dipole-trapped atoms ranges from more than ten thousand to below ten. The dipole-trapped atoms are detected either by a photon counting system with very efficient straylight discrimination, or by recapture into the MOT, which is imaged onto a sensitive photodiode and a CCD-camera. Due to the strong AC-Stark shift imposed by the high intensity trapping light, energy-selective resonant excitation and detection of the atoms is possible. The measured energy distribution is consistent with a harmonic potential shape and allows the determination of temperatures and heating rates. In first measurements, the thermal energy is found to be about 10 % of the trap

  13. Beam halo studies in LEHIPA DTL

    International Nuclear Information System (INIS)

    The Low Energy High Intensity Proton Accelerator (LEHIPA) project at Bhabha Atomic Research Centre (BARC) consists of a 20 MeV, 30 mA proton linac. The accelerator comprises of a 3 MeV Radio Frequency Quadrupole (RFQ) and a 20 MeV Drift Tube Linac (DTL). In such high intensity accelerators, beam halos are of concern as they not only cause an increase in emittance, but also lead to beam loss and radio activation. We have studied the effect of beam mismatch at the DTL input on halo formation and propagation. The particle core model is used to excite the three envelope eigen modes; the quadrupole mode, the fast mode and the slow mode by giving input beam mismatch. These modes get damped as the beam progresses through the DTL. The damping mechanism is clearly Landau damping and leads to increase in rms emittance of the beam. The evolution of these modes and the corresponding increase in beam emittance and maximum beam extent, as the beam propagates through the DTL, has been studied for different space charge tunes. The halo parameter based on the definition of Allen and Wangler has been calculated. It is seen that beam halos are very important for LEHIPA DTL, even at 20 MeV and leads to emittance and beam size increase and also to beam loss in some cases. The longitudinal halo is present even without mismatch and transverse halos arise in the presence of beam mismatch

  14. Single atom measurement and atomic manipulation using atomic force microscope

    International Nuclear Information System (INIS)

    This paper explains studies to measure atomic force as the force linking an atom and atom, using an atomic force microscope (AFM). First, it describes the principle and device configuration of AFM, and as an example of the atomic force measurement of Si atoms on the surface of Si(111)-(7x7), it describes the technique to measure atomic force using AFM, as well as the uncertainty of probe tip against atomic force. In addition, it describes the following items on the measurement results of chemical bonding force: (1) chemical bonding force vs physical force and chemical bonding force vs current on the surface of Si(111)-(7x7), (2) chemical bonding force and element dependence on the surface of Si/Sn(111)-(√3x√3), (3) atomic manipulation based on AMF, and (4) relationship between atomic manipulation and the size of chemical bonding force with a probe. (A.O.)

  15. 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.

  16. Beam optics of the folded tandem ion accelerator at BARC

    Indian Academy of Sciences (India)

    S Santra; P Singh

    2002-07-01

    The beam optics of the 6 MV folded tandem ion accelerator, that has recently been commissioned at Bhabha Atomic Research Centre, Mumbai, is presented. Typical beam trajectories for proton and 12C beams under different conditions, are shown. The constraints on the design due to the use of the infrastructure of the Van de Graaff accelerator, which existed earlier, are discussed.

  17. Phasor analysis of atom diffraction from a rotated material grating

    CERN Document Server

    Cronin, A D; Cronin, Alexander D.; Perreault, John D.

    2003-01-01

    The strength of an atom-surface interaction is determined by studying atom diffraction from a rotated material grating. A phasor diagram is developed to interpret why diffraction orders are never completely suppressed when a complex transmission function due to the van der Waals interaction is present. We also show that atom-surface interactions can produce asymmetric diffraction patterns. Our conceptual discussion is supported by experimental observations with a sodium atom beam.

  18. Atom capture and loss in ion molecule collisions

    International Nuclear Information System (INIS)

    Progress is reported in measuring the energy and angular distribution of protons emerging with velocity close to the beam velocity from the target region when Ar+ beams collide with a CH4 target and ArH+ beams collide with a He target at asymptotically high speeds. The protons result from the transfer of a target constituent to the projectile (atom capture) or from the dissociation of the projectile molecule in the collision (atom loss). For atom capture processes the Thomas peak is clearly observed. 10 refs., 3 figs

  19. Crossed-beam reaction of carbon atoms with hydrocarbon molecules. IV. Chemical dynamics of methylpropargyl radical formation, C{sub 4}H{sub 5}, from reaction of C({sup 3}P{sub j}) with propylene, C{sub 3}H{sub 6} (X{sup 1}A)

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, R.I.; Stranges, D.; Bevsek, H.M.; Lee, Y.T.; Suits, A.G. [Department of Chemistry, University of California, Berkeley, California 94720 (United States)]|[Chemical Sciences Division, Berkeley National Laboratory, Berkeley, California 94720 (United States)

    1997-03-01

    The reaction between ground state carbon atoms and propylene, C{sub 3}H{sub 6}, was studied at average collision energies of 23.3 and 45.0 kJmol{sup {minus}1} using the crossed molecular beam technique. Product angular distributions and time-of-flight spectra of C{sub 4}H{sub 5} at m/e=53 were recorded. Forward-convolution fitting of the data yields a maximum energy release as well as angular distributions consistent with the formation of methylpropargyl radicals. Reaction dynamics inferred from the experimental results suggest that the reaction proceeds on the lowest {sup 3}A surface via an initial addition of the carbon atom to the {pi}-orbital to form a triplet methylcyclopropylidene collision complex followed by ring opening to triplet 1,2-butadiene. Within 0.3{endash}0.6 ps, 1,2-butadiene decomposes through carbon{endash}hydrogen bond rupture to atomic hydrogen and methylpropargyl radicals. The explicit identification of C{sub 4}H{sub 5} under single collision conditions represents a further example of a carbon{endash}hydrogen exchange in reactions of ground state carbon with unsaturated hydrocarbons. This versatile machine represents an alternative pathway to build up unsaturated hydrocarbon chains in combustion processes, chemical vapor deposition, and in the interstellar medium. {copyright} {ital 1997 American Institute of Physics.}

  20. RIKEN RI Beam Factory project

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Yasushige; Goto, Akira; Katayama, Takeshi [Institute of Physical and Chemical Research, Wako, Saitama (Japan)

    1997-03-01

    The RARF proposes `RIKEN RI Beam Factory` as a next facility-expanding project. The factory makes it the primary aim to provide RI (Radioactive Isotope) beams covering over the whole atomic-mass range with the world-highest intensity in a wide energy range up to several hundreds MeV/nucleon. These RI beams are generated by the fragmentation of high-intensity heavy-ion beams. For the efficient production heavy-ion energies will be boosted up to over 100 MeV/nucleon even for very heavy ions by a K2500-MeV superconducting ring cyclotron serving as a post accelerator of the existing K540-MeV ring cyclotron. A new type of experimental installation called `MUSES` (Multi-USe Experimental Storage rings) will be constructed as well. With MUSES, various types of unique colliding experiments will become possible. (author)

  1. Magnetic Trapping of Cold Bromine Atoms

    CERN Document Server

    Rennick, C J; Doherty, W G; Softley, T P

    2014-01-01

    Magnetic trapping of bromine atoms at temperatures in the milliKelvin regime is demonstrated for the first time. The atoms are produced by photodissociation of Br$_2$ molecules in a molecular beam. The lab-frame velocity of Br atoms is controlled by the wavelength and polarization of the photodissociation laser. Careful selection of the wavelength results in one of the pair of atoms having sufficient velocity to exactly cancel that of the parent molecule, and it remains stationary in the lab frame. A trap is formed at the null point between two opposing neodymium permanent magnets. Dissociation of molecules at the field minimum results in the slowest fraction of photofragments remaining trapped. After the ballistic escape of the fastest atoms, the trapped slow atoms are only lost by elastic collisions with the chamber background gas. The measured loss rate is consistent with estimates of the total cross section for only those collisions transferring sufficient kinetic energy to overcome the trapping potential...

  2. Spatial light modulators for cold atom manipulation

    International Nuclear Information System (INIS)

    Full text: Spatial Light Modulators (SLM's) are programmable optical elements that can act as dynamical phase holograms on laser beams. Thus, a laser beam can be shaped into a pattern which is the Fourier transform of the hologram. It provides a flexible method to create dipole potentials in order to manipulate small objects. In this context, our group is investigating experiments using SLM's for cold atom cloud manipulation. First we have focused on response time and diffraction pattern quality issues. We have demonstrated a device involving a SLM and an acousto-optic modulator (AOM/SLM) with a refresh time of some micro-seconds and without bleed effect during the hologram changes. This device would be well-suited for cold atom manipulation with time-dependent dipole potentials. We have also studied different algorithms to calculate holograms. Then, we have experimented the method on cold rubidium atoms, by applying a blue detuned laser shaped into a hollow Laguerre-Gaussian beam. Such a profile is obtained by applying a helical-phase hologram to the laser beam. The cold atoms have been guided during their fall due to gravity, into the dark region of the Laguerre-Gaussian mode. Being far-detuned from resonance and dark where the atoms spend most of their time, the light field causes little scattering-induced losses and guiding is efficient. The efficiency is studied versus the detuning and the order of the Laguerre-Gaussian beam and is compared to a model for the atom capture into the two-dimensional potential. Future applications of this technique will be presented and discussed in the context of cold atoms or Bose-Einstein condensates experiments. (author)

  3. Laser trapping of 21Na atoms

    International Nuclear Information System (INIS)

    This thesis describes an experiment in which about four thousand radioactive 21Na (tl/2 = 22 sec) atoms were trapped in a magneto-optical trap with laser beams. Trapped 21Na atoms can be used as a beta source in a precision measurement of the beta-asymmetry parameter of the decay of 21Na → 21Ne + Β+ + ve, which is a promising way to search for an anomalous right-handed current coupling in charged weak interactions. Although the number o trapped atoms that we have achieved is still about two orders of magnitude lower than what is needed to conduct a measurement of the beta-asymmetry parameter at 1% of precision level, the result of this experiment proved the feasibility of trapping short-lived radioactive atoms. In this experiment, 21Na atoms were produced by bombarding 24Mg with protons of 25 MeV at the 88 in. Cyclotron of Lawrence Berkeley Laboratory. A few recently developed techniques of laser manipulation of neutral atoms were applied in this experiment. The 21Na atoms emerging from a heated oven were first transversely cooled. As a result, the on-axis atomic beam intensity was increased by a factor of 16. The atoms in the beam were then slowed down from thermal speed by applying Zeeman-tuned slowing technique, and subsequently loaded into a magneto-optical trap at the end of the slowing path. The last two chapters of this thesis present two studies on the magneto-optical trap of sodium atoms. In particular, the mechanisms of magneto-optical traps at various laser frequencies and the collisional loss mechanisms of these traps were examined

  4. A quantum gas microscope for ytterbium atoms

    Science.gov (United States)

    Takahashi, Yoshiro

    2016-05-01

    In this talk, I report on the development of a quantum gas microscope for ytterbium (Yb) atoms. By using a dual molasses technique in which 399 nm molasses beams of the broad singlet transition are applied for fluorescence imaging and 556 nm molasses beams of the narrow intercombination transition are applied for cooling during the imaging, we successfully demonstrate site-resolved imaging of individual bosonic 174 Yb atoms in a two-dimensional optical lattice with a lattice constant of 266 nm.We also apply a high resolution laser spectroscopy using the ultranarrow intercombination transition between the 1 S0 and 3 P2 states to manipulate an atom distribution in an optical lattice. We expect the demonstrated technique will similarly work for other isotopes of Yb atoms. We are also developing a different mode of an Yb quantum gas microscope.

  5. Magnetic measurements with atomic-plane resolution.

    Science.gov (United States)

    Rusz, Ján; Muto, Shunsuke; Spiegelberg, Jakob; Adam, Roman; Tatsumi, Kazuyoshi; Bürgler, Daniel E; Oppeneer, Peter M; Schneider, Claus M

    2016-01-01

    Rapid development of magnetic nanotechnologies calls for experimental techniques capable of providing magnetic information with subnanometre spatial resolution. Available probes of magnetism either detect only surface properties, such as spin-polarized scanning tunnelling microscopy, magnetic force microscopy or spin-polarized low-energy electron microscopy, or they are bulk probes with limited spatial resolution or quantitativeness, such as X-ray magnetic circular dichroism or classical electron magnetic circular dichroism (EMCD). Atomic resolution EMCD methods have been proposed, although not yet experimentally realized. Here, we demonstrate an EMCD technique with an atomic size electron probe utilizing a probe-corrected scanning transmission electron microscope in its standard operation mode. The crucial element of the method is a ramp in the phase of the electron beam wavefunction, introduced by a controlled beam displacement. We detect EMCD signals with atomic-plane resolution, thereby bringing near-atomic resolution magnetic circular dichroism spectroscopy to hundreds of laboratories worldwide. PMID:27578421

  6. Continuous magnetic trapping of laser cooled atoms

    International Nuclear Information System (INIS)

    The authors present here initial results of the deceleration of a thermal atomic beam from -- 1000 to -- 100 m/s. The experiment was conducted in the 1.4-m long vertical superconducting solenoid which produced the slowing field. The fluorescence of the slowed atomic beam has been studied as a function of laser frequency. Figure 2 is a 12-GHz scan showing the fluorescence at a position 150 cm from the beginning of the solenoid. The wide peak corresponds to unslowed atoms with generally the initial velocity distribution. The second, narrower, peak corresponds to slowed atoms with a velocity of -- 150 m/s. Similar spectra have been obtained for various positions along the magnetic slower and trap. These data should allow better understanding of the cooling process and will be compared to computer models

  7. Positron impact ionization of atomic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Jones, G.O.; Charlton, M.; Slevin, J.; Laricchia, G.; Kover, A.; Poulsen, M.R.; Chormaic, S.N. (University Coll., London (United Kingdom). Dept. of Physics and Astronomy)

    1993-08-14

    Ionization cross sections for positrons impacting on atomic hydrogen have been measured for kinetic energies in the range 15-700 eV. This has been done in a crossed-beam geometry where a magnetically guided positron beam intersects a hydrogen gas jet emanating from a radio frequency discharge tube. Electron impact ionization cross sections were also measured with the same apparatus thus facilitating comparison with, and normalization to, published results. (author).

  8. Positron impact ionization of atomic hydrogen

    International Nuclear Information System (INIS)

    Ionization cross sections for positrons impacting on atomic hydrogen have been measured for kinetic energies in the range 15-700 eV. This has been done in a crossed-beam geometry where a magnetically guided positron beam intersects a hydrogen gas jet emanating from a radio frequency discharge tube. Electron impact ionization cross sections were also measured with the same apparatus thus facilitating comparison with, and normalization to, published results. (author)

  9. Demonstration of a Sagnac-Type Cold Atom Interferometer with Stimulated Raman Transitions

    Institute of Scientific and Technical Information of China (English)

    WANG Ping; LI Run-Bing; YAN Hui; WANG Jin; ZHAN Ming-Sheng

    2007-01-01

    @@ Cold-matter-wave Sagnac interferometers possess many advantages over their thermal atomic beam counterparts when they are used as precise inertial sensors. We report a realization of a Sagnac-type interferometer with cold atoms.

  10. Machines géantes pour sonder l'univers de l'atome

    CERN Multimedia

    Wilde, M, S

    1966-01-01

    To always more deeply explore the infinitely small world of the atom, Science is paradoxically brought to build buildings and machines increasingly larger - Giant accelerators producing high energy particle beams that can dissociate the structures of the atomic nucleus

  11. The preparation of layers with atomic accuracy parameters for micro and nano technology purposes

    International Nuclear Information System (INIS)

    Atomic layer epitaxy is a new technology to prepare micro and nanostructures. The technology is used to prepare electrooptical devices with extreme high geometrical accuracy. The structures are investigated with atomic force microscopy and electron beam microanalysis.

  12. Nonlocality with ultracold atoms in a lattice

    Science.gov (United States)

    Pelisson, Sophie; Pezzè, Luca; Smerzi, Augusto

    2016-02-01

    We study the creation of nonlocal states with ultracold atoms trapped in an optical lattice. We show that these states violate Bell inequality by measuring one- and two-body correlations. Our scheme only requires beam-splitting operations and global phase shifts, and can be realized within the current technology, employing single-site addressing. This proposal paves the way to study multipartite nonlocality and entanglement in ultracold-atomic systems.

  13. Microwave Power Standard using Cold Atoms

    CERN Document Server

    Paulusse, D C; Michaud, A; Paulusse, David C; Rowell, Nelson L; Michaud, Alain

    2003-01-01

    We discuss how the observation of Rabi flopping oscillations in a laser cooled atomic sample could be used as a microwave power standard. The rubidium atoms are first trapped in a standard MOT, then optically pumped, and dropped. As they enter the interaction region, a resonant pulsed microwave field is applied. Following the interaction lasting up to 10 ms, a probe laser beam is turned on and the fluorescence measures the population inversion.

  14. Atomic mirrors for a Λ-type three-level atom

    International Nuclear Information System (INIS)

    We propose atom mirror schemes for a three-level atom of Λ-type interacting with two evanescent fields, which are generated as a result of the total internal reflection of two coherent Gaussian laser beams at the interface of a dielectric prism with vacuum. The forces acting on the atom are derived by means of optical Bloch equations, based on the atomic density matrix elements. The theory is illustrated by setting up the equations of motion for 23Na atom. Two types of excited schemes are examined, namely the cases in which the evanescent fields have polarization types of σ+−σ− and σ+−π. The equations are solved numerically and we get results for atomic trajectories for different parameters. The performance of the mirror for the two types of polarization schemes is quantified and discussed. The possibility of reflecting atoms at pre-determined directions is also discussed. (paper)

  15. Beam emittance and beam disruption

    International Nuclear Information System (INIS)

    Beam disruption during the collision of intense relativistic bunches has been studied by R. Hollebeek. In the case of oppositely charged bunches, focussing effects occur causing a decrease in the effective bunch cross section, and thereby an increase of luminosity by an enhancement factor H. The term disruption derives from the fact that the beam emittance changes markedly during the collision. 1 ref., 1 fig., 1 tab

  16. Production of annular flat-topped vortex beams

    Institute of Scientific and Technical Information of China (English)

    Jiannong Chen; Yongjiang Yu; Feifei Wang

    2011-01-01

    @@ A model of an annular flat-topped vortex beam based on multi-Gaussian superimposition is proposed. We experimentally produce this beam with a computer-generated hologram (CGH) displayed on a spatial light modulator (SLM). The power of the beam is concentrated on a single-ring structure and has an extremely strong radial intensity gradient. This beam facilitates various applications ranging from Sisyphus atom cooling to micro-particle trapping.%A model of an annular fiat-topped vortex beam based on multi-Gaussian superimposition is proposed. We experimentally produce this beam with a computer-generated hologram (CGH) displayed on a spatial light modulator (SLM). The power of the beam is concentrated on a single-ring structure and has an extremely strong radial intensity gradient. This beam facilitates various applications ranging from Sisyphus atom cooling to micro-particle trapping.

  17. A high density target of ultracold atoms and momentum resolved measurements of ion-atom collisions

    OpenAIRE

    Götz, Simone Andrea

    2012-01-01

    In this thesis an ultracold high density target with high loading flux in combination with a recoil ion momentum spectrometer (RIMS) is presented. Trapped rubidium atoms serve as a high density target (up to 10¹¹ atoms/cm³) at a temperature of only 200 µK. The target is loaded from a two-dimensional magneto-optical trap (2D MOT), which delivers an atom beam with a brilliance of 8 x 10¹² atoms/(s*rad) and a longitudinal momentum spread of 0.25 a.u.. The great advantage of this source is that t...

  18. Recirculation of Laser Power in an Atomic Fountain

    Science.gov (United States)

    Enzer, Daphna G.; Klipstein, WIlliam M.; Moore, James D.

    2007-01-01

    A new technique for laser-cooling atoms in a cesium atomic fountain frequency standard relies on recirculation of laser light through the atom-collection region of the fountain. The recirculation, accomplished by means of reflections from multiple fixed beam-splitter cubes, is such that each of two laser beams makes three passes. As described below, this recirculation scheme offers several advantages over prior designs, including simplification of the laser system, greater optical power throughput, fewer optical and electrical connections, and simplification of beam power balancing. A typical laser-cooled cesium fountain requires the use of six laser beams arranged as three orthogonal pairs of counter-propagating beams to decelerate the atoms and hold them in a three-dimensional optical trap in vacuum. Typically, these trapping/cooling beams are linearly polarized and are positioned and oriented so that (1) counter-propagating beams in each pair have opposite linear polarizations and (2) three of the six orthogonal beams have the sum of their propagation directions pointing up, while the other three have the sum of their propagation directions pointing down. In a typical prior design, two lasers are used - one to generate the three "up" beams, the other to generate the three "down" beams. For this purpose, the output of each laser is split three ways, then the resulting six beams are delivered to the vacuum system, independently of each other, via optical fibers. The present recirculating design also requires two lasers, but the beams are not split before delivery. Instead, only one "up" beam and one oppositely polarized "down" beam are delivered to the vacuum system, and each of these beams is sent through the collection region three times. The polarization of each beam on each pass through the collection region is set up to yield the same combination of polarization and propagation directions as described above. In comparison with the prior design, the present

  19. Advanced neutral-beam technology

    International Nuclear Information System (INIS)

    Extensive development will be required to achieve the 50- to 75-MW, 175- to 200-keV, 5- to 10-sec pulses of deuterium atoms envisioned for ETF and INTOR. Multi-megawatt injector systems are large (and expansive); they consist of large vacuum tanks with many square meters of cryogenic pumping panels, beam dumps capable of dissipating several megawatts of un-neutralized beam, bending magnets, electrical power systems capable of fast turnoff with low (capacity) stored energy, and, of course, the injector modules (ion sources and accelerators). The technology requirements associated with these components are described

  20. Slow polaritons with orbital angular momentum in atomic gases

    CERN Document Server

    Ruseckas, J; Juzeliunas, G; 10.1103/PhysRevA.83.023812

    2011-01-01

    Polariton formalism is applied for studying the propagation of a probe field of light in a cloud of cold atoms influenced by two control laser beams of larger intensity. The laser beams couple resonantly three hyperfine atomic ground states to a common excited state thus forming a tripod configuration of the atomic energy levels involved. The first control beam can have an optical vortex with the intensity of the beam going to zero at the vortex core. The second control beam without a vortex ensures the loseless (adiabatic) propagation of the probe beam at a vortex core of the first control laser. We investigate the storage of the probe pulse into atomic coherences by switching off the control beams, as well as its subsequent retrieval by switching the control beams on. The optical vortex is transferred from the control to the probe fields during the storage or retrieval of the probe field. We analyze conditions for the vortex to be transferred efficiently to the regenerated probe beam and discuss possibiliti...