WorldWideScience

Sample records for atomic beams

  1. 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

  2. A continuous cold atomic beam interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Hongbo [State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084 (China); Joint Institute for Measurement Science, Tsinghua University, Beijing 100084 (China); Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China); Feng, Yanying, E-mail: yyfeng@tsinghua.edu.cn; Yan, Xueshu; Jiang, Zhikun [State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084 (China); Joint Institute for Measurement Science, Tsinghua University, Beijing 100084 (China); Chen, Shu [Joint Institute for Measurement Science, Tsinghua University, Beijing 100084 (China); Key Laboratory of Instrumentation Science, North University of China, Taiyuan 030051 (China); Wang, Xiaojia [College of Mechanical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zhou, Zhaoying [State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084 (China)

    2015-03-07

    We demonstrate an atom interferometer that uses a laser-cooled continuous beam of {sup 87}Rb 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 mm{sup 2} at a bandwidth of 190 Hz with a deduced sensitivity of 7.8×10{sup −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.

  3. Relativistic atomic beam spectroscopy II

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1989-12-31

    The negative ion of H is one of the simplest 3-body atomic systems. The techniques we have developed for experimental study of atoms moving near speed of light have been productive. This proposal request continuing support for experimental studies of the H{sup -} system, principally at the 800 MeV linear accelerator (LAMPF) at Los Alamos. Four experiments are currently planned: photodetachment of H{sup -} near threshold in electric field, interaction of relativistic H{sup -} ions with matter, high excitations and double charge escape in H{sup -}, and multiphoton detachment of electrons from H{sup -}.

  4. Relativistic atomic beam spectroscopy II

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-12-31

    We are requesting support for a postdoctoral person to participate in H{sup -} studies at Los Alamos. In addition, we are requesting funding for a state-of-the-art YAG laser system that would allow us to obtain data at three times our present rate with improved beam quality.

  5. Cold atomic beam ion source for focused ion beam applications

    Energy Technology Data Exchange (ETDEWEB)

    Knuffman, B.; Steele, A. V. [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Maryland Nanocenter, University of Maryland, College Park, Maryland 20742 (United States); zeroK NanoTech, Montgomery Village, Maryland 20886 (United States); McClelland, J. J. [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

    2013-07-28

    We report measurements and modeling of an ion source that is based on ionization of a laser-cooled atomic beam. We show a high brightness and a low energy spread, suitable for use in next-generation, high-resolution focused ion beam systems. Our measurements of total ion current as a function of ionization conditions support an analytical model that also predicts the cross-sectional current density and spatial distribution of ions created in the source. The model predicts a peak brightness of 2 × 10{sup 7} A m{sup −2} sr{sup −1} eV{sup −1} and an energy spread less than 0.34 eV. The model is also combined with Monte-Carlo simulations of the inter-ion Coulomb forces to show that the source can be operated at several picoamperes with a brightness above 1 × 10{sup 7} A m{sup −2} sr{sup −1} eV{sup −1}. We estimate that when combined with a conventional ion focusing column, an ion source with these properties could focus a 1 pA beam into a spot smaller than 1 nm. A total current greater than 5 nA was measured in a lower-brightness configuration of the ion source, demonstrating the possibility of a high current mode of operation.

  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. 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.

  8. Diffraction of an atomic beam by standing-wave radiation

    Science.gov (United States)

    Moskowitz, P. E.; Gould, P. L.; Atlas, S. R.; Pritchard, D. E.

    1983-08-01

    Preliminary experimental results are reported for the deflection of Na atoms in an atomic beam by a transverse standing-wave laser field whose frequency is tuned between the two ground-state hyperfine components of the D2 line. In contrast to the two experiments done previously, a splitting of the beam into two symmetric peaks whose separation increases with the electric-field is seen here. In addition, the data show evidence for atomic diffraction: a tendency for scattered atoms to acquire momentum in multiples of 2h(bar)k.

  9. Precision atomic beam density characterization by diode laser absorption spectroscopy.

    Science.gov (United States)

    Oxley, Paul; Wihbey, Joseph

    2016-09-01

    We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10-5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 104 atoms cm-3. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

  10. 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.

  11. Two-Photon Coherent Atomic Absorption of Multiple Laser Beams

    Science.gov (United States)

    Li, Ming-Chiang

    2006-05-01

    Physical processes on two-photon coherent atomic absorption of multiple laser beams were discussed about thirty years ago [M. C. Li, Bull. Am. Phys. Soc. 20, 654 (1975)]. These processes can be divided into two distinct groups. In the first group, laser beams are from a single source, and in the second group laser beams are from two different sources [M. C. Li, Phys. Rev. A 22 (1980) 1323]. Several experiments in the first group were carried out and have led to the 2005 Nobel Prize in physics. The second group is more interesting. Beside atoms are in random motion, two photons are from different sources. Classically, it is impossible for atoms to transit coherently in the absorption process, but quantum mechanically, such a transition is possible and that is one of the spooky phenomena in quantum mechanic. To assure the coherent transition, each photon as absorbed by the atom must have two possible paths of choices. If one photon has the choice and other one is not, then the atomic transitions cannot be coherent. Around1990, there were very active experimental pursuits on such a spooky phenomenon of two photons emitted from crystal parametric down conversion. The present talk will review various spooky phenomena associated with two-photon coherent atomic absorption. Hope that the talk will stimulate the interest on the long neglected experimental front on two-photon coherent atomic absorption from two different laser sources.

  12. Internal polarized deuterium target with cryogenic atomic beam source

    CERN Document Server

    Dyug, M V; Lazarenko, B A; Mishnev, S I; Nikolenko, D M; Rachek, Igor A; Shestakov, Yu V; Sadykov, R S; Toporkov, D K; Zevakov, S A; Osipov, A V; Stibunov, V N

    2002-01-01

    Description of the polarized deuterium gas target used at the VEPP-3 electron storage ring for experiments on elastic and inelastic ed scattering is given. Superconducting sextupole magnets with the pole tip magnetic field up to 4.8 T are used in atomic beam source (ABS) to focus atoms. The flux of polarized atoms injected into the storage cell was measured to be 8.2x10 sup 1 sup 6 at/s for deuterium and 7.9x10 sup 1 sup 6 at/s for hydrogen. The measured target thickness 8x10 sup 1 sup 3 at/cm sup 2 is consistent with the thickness calculated from the measured beam intensity. The effective tensor polarization of the deuterium target during the experiment was found to be P sub z sub z =0.397. Further improvements of the target and possible limitation of the beam intensity from ABS are discussed.

  13. 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.

  14. 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.

  15. 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.

  16. Molecular beam studies of hot atom chemical reactions: Reactive scattering of energetic deuterium atoms

    Energy Technology Data Exchange (ETDEWEB)

    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/ /minus/> DH + H and the substitution reaction D + C/sub 2/H/sub 2/ /minus/> 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. 18 refs., 9 figs.

  17. Direct detection of momentum flux in atomic and molecular beams

    Science.gov (United States)

    Choi, J. G.; Hayden, J. S.; O'Connor, M. T.; Diebold, G. J.

    1981-10-01

    We describe the use of a microphone for detection of atomic and molecular beams in a high-vacuum environment. Two experiments were carried out to demonstrate this detection method. Pulsed beams of argon were detected using a conventional electret microphone where the output of the microphone was displayed directly on an oscilloscope or processed with a boxcar averager to remove the transient oscillations of the microphone diaphragm. Amplitude modulated, continuous beams of atomic argon were also detected using a lock-in amplifier. The microphone possesses a response to the pressure or momentum flux in the beam that appears to be unique among beam detectors. We use the classical equipartition theorem to calculate the magnitude of the random fluctuations in the output voltage of the microphone that is used to give an expression for the minimum detectable momentum flux in the beam. For a typical microphone we find this to be 3×10-8 Pa, (in a 1-Hz bandwidth), which corresponds to a minimum number density of 1×106 cm-3 for an effusive argon beam at 300 K.

  18. Sensitivity of MSE measurements on the beam atomic level population.

    Science.gov (United States)

    Ruiz, C; Kumar, S T A; Anderson, F S B; Anderson, D T

    2016-11-01

    The effect of variation in atomic level population of a neutral beam on the Motional Stark Effect (MSE) measurements is investigated in the low density plasmas of HSX stellarator. A 30 KeV, 4 A, 3 ms hydrogen diagnostic neutral beam is injected into HSX plasmas of line averaged electron density ranging from 2 to 4 ⋅ 1018 m-3 at a magnetic field of 1 T. For this density range, the excited level population of the hydrogen neutral beam is expected to undergo variations. Doppler shifted and Stark split Hα and Hβ emissions from the beam are simultaneously measured using two cross-calibrated spectrometers. The emission spectrum is simulated and fit to the experimental measurements and the deviation from a statistically populated beam is investigated.

  19. Sensitivity of MSE measurements on the beam atomic level population

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, C., E-mail: carlos.ruiz@wisc.edu; Kumar, S. T. A.; Anderson, F. S. B.; Anderson, D. T. [University of Wisconsin–Madison, Madison, Wisconsin 53706 (United States)

    2016-11-15

    The effect of variation in atomic level population of a neutral beam on the Motional Stark Effect (MSE) measurements is investigated in the low density plasmas of HSX stellarator. A 30 KeV, 4 A, 3 ms hydrogen diagnostic neutral beam is injected into HSX plasmas of line averaged electron density ranging from 2 to 4 ⋅ 10{sup 18} m{sup −3} at a magnetic field of 1 T. For this density range, the excited level population of the hydrogen neutral beam is expected to undergo variations. Doppler shifted and Stark split H{sub α} and H{sub β} emissions from the beam are simultaneously measured using two cross-calibrated spectrometers. The emission spectrum is simulated and fit to the experimental measurements and the deviation from a statistically populated beam is investigated.

  20. 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.

  1. 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.

  2. Development of atomic beam probe for tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Berta, M., E-mail: bertam@sze.hu [Széchenyi István University, EURATOM Association, Győr (Hungary); Institute of Plasma Physics AS CR, v.v.i., Prague (Czech Republic); Anda, G.; Aradi, M.; Bencze, A.; Buday, Cs.; Kiss, I.G.; Tulipán, Sz.; Veres, G.; Zoletnik, S. [Wigner – RCP, HAS, EURATOM Association, Budapest (Hungary); Havlícek, J.; Háček, P. [Institute of Plasma Physics AS CR, v.v.i., Prague (Czech Republic); Charles University in Prague, Faculty of Mathematics and Physics (Czech Republic)

    2013-11-15

    Highlights: • ABP is newly developed diagnostic. • Unique measurement method for the determination of plasma edge current variations caused by different transient events such as ELMs. • The design process has been fruitfully supported by the physically motivated computer simulations. • Li-BES system has been modified accordingly to the needs of the ABP. -- Abstract: The concept and development of a new detection method for light alkali ions stemming from diagnostic beams installed on medium size tokamak is described. The method allows us the simultaneous measurement of plasma density fluctuations and fast variations in poloidal magnetic field, therefore one can infer the fast changes in edge plasma current. The concept has been worked out and the whole design process has been done at Wigner RCP. The test detector with appropriate mechanics and electronics is already installed on COMPASS tokamak. General ion trajectory calculation code (ABPIons) has also been developed. Detailed calculations show the possibility of reconstruction of edge plasma current density profile changes with high temporal resolution, and the possibility of density profile reconstruction with better spatial resolution compared to standard Li-BES measurement, this is important for pedestal studies.

  3. 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.

  4. Toward single mode, atomic size electron vortex beams.

    Science.gov (United States)

    Krivanek, Ondrej L; Rusz, Jan; Idrobo, Juan-Carlos; Lovejoy, Tracy J; Dellby, Niklas

    2014-06-01

    We propose a practical method of producing a single mode electron vortex beam suitable for use in a scanning transmission electron microscope (STEM). The method involves using a holographic "fork" aperture to produce a row of beams of different orbital angular momenta, as is now well established, magnifying the row so that neighboring beams are separated by about 1 µm, selecting the desired beam with a narrow slit, and demagnifying the selected beam down to 1-2 Å in size. We show that the method can be implemented by adding two condenser lenses plus a selection slit to a straight-column cold-field emission STEM. It can also be carried out in an existing instrument, the monochromated Nion high-energy-resolution monochromated electron energy-loss spectroscopy-STEM, by using its monochromator in a novel way. We estimate that atom-sized vortex beams with ≥ 20 pA of current should be attainable at 100-200 keV in either instrument.

  5. 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).

  6. The quantum measurement effect of interaction without interaction for an atomic beam

    Science.gov (United States)

    Huang, Yong-Yi

    When an atomic beam collectively and harmonically vibrates perpendicular to the wave vector of the beam, the number of atoms reaching the atomic detector will have a vibrant factor Δt / T if the measurement time interval Δt is shorter than the period T. This new quantum mechanical measurement effect for an atomic beam is called interaction without interaction: though the translational motion of the atomic beam does not interact with its collective and transverse harmonic vibration, the latter will have an effect on the measured number of atoms associated with the former. From the new measurement effect the classical harmonic vibration's period is evaluated. We give a clear physical picture and a satisfactory physical interpretation for the measurement effect based on the Copenhagen interpretation of quantum mechanics. We present an experimental proposal to verify this measurement effect for an ion beam instead of an atomic beam.

  7. Cold beam of isotopically pure Yb atoms by deflection using 1D ...

    Indian Academy of Sciences (India)

    Both clock and EDM measurements gain from having a cold continuous beam of atoms that is separated from the cooling laser beams. For atomic clocks, a continuous beam avoids intermodulation or the Dick effect [10], seen in pulsed fountain clocks. For. EDM experiments, the electric-field plates can be brought very close ...

  8. Geometric optics with atomic beams scattered by a detuned standing laser wave

    CERN Document Server

    Prants, S V; Konkov, L E

    2012-01-01

    We report on theoretical and numerical study of propagation of atomic beams crossing a detuned standing-wave laser beam in the geometric oprics limit. The interplay between external and internal atomic degrees of freedom is used to manipulate the atomic motion along the optical axis by light. By adjusting the atom-laser detuning, we demonstrate how to focus, split and scatter atomic beams in a real experiment. The novel effect of chaotic scattering of atoms at a regular near-resonant standing wave is found numerically and explained qualitatively. Some applications of the effects found are discussed.

  9. Thermal beam of metastable krypton atoms produced by optical excitation.

    Science.gov (United States)

    Ding, Y; Hu, S M; Bailey, K; Davis, A M; Dunford, R W; Lu, Z T; O'Connor, T P; Young, L

    2007-02-01

    A room-temperature beam of krypton atoms in the metastable 5s[3/2]2 level is demonstrated via an optical excitation method. A Kr-discharge lamp is used to produce vacuum ultraviolet photons at 124 nm for the first-step excitation from the ground level 4p6 1S0 to the 5s[3/2]1 level. An 819 nm Ti:sapphire laser is used for the second-step excitation from 5s[3/2]1 to 5s[3/2]2 followed by a spontaneous decay to the 5s[3/2]2 metastable level. A metastable atomic beam with an angular flux density of 3 x 10(14) s(-1) sr(-1) is achieved at the total gas flow rate of 0.01 cm3/s at STP (or 3 x 10(17) at./s). The dependences of the flux on the gas flow rate, laser power, and lamp parameters are investigated.

  10. Fabrication of electron beam deposited tip for atomic-scale atomic force microscopy in liquid.

    Science.gov (United States)

    Miyazawa, K; Izumi, H; Watanabe-Nakayama, T; Asakawa, H; Fukuma, T

    2015-03-13

    Recently, possibilities of improving operation speed and force sensitivity in atomic-scale atomic force microscopy (AFM) in liquid using a small cantilever with an electron beam deposited (EBD) tip have been intensively explored. However, the structure and properties of an EBD tip suitable for such an application have not been well-understood and hence its fabrication process has not been established. In this study, we perform atomic-scale AFM measurements with a small cantilever and clarify two major problems: contaminations from a cantilever and tip surface, and insufficient mechanical strength of an EBD tip having a high aspect ratio. To solve these problems, here we propose a fabrication process of an EBD tip, where we attach a 2 μm silica bead at the cantilever end and fabricate a 500-700 nm EBD tip on the bead. The bead height ensures sufficient cantilever-sample distance and enables to suppress long-range interaction between them even with a short EBD tip having high mechanical strength. After the tip fabrication, we coat the whole cantilever and tip surface with Si (30 nm) to prevent the generation of contamination. We perform atomic-scale AFM imaging and hydration force measurements at a mica-water interface using the fabricated tip and demonstrate its applicability to such an atomic-scale application. With a repeated use of the proposed process, we can reuse a small cantilever for atomic-scale measurements for several times. Therefore, the proposed method solves the two major problems and enables the practical use of a small cantilever in atomic-scale studies on various solid-liquid interfacial phenomena.

  11. Towards Demonstration of a MOT-Based Continuous Cold CS-Beam Atomic Clock

    National Research Council Canada - National Science Library

    Wang, H; Camparo, J. C; Iyanu, G

    2007-01-01

    ... (MOT). This technique has the unique advantage of generating a useful cold atomic beam just outside the volume of a MOT and, hence, can greatly reduce the size of the atomic clock physics package...

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

    Science.gov (United States)

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

    2014-03-01

    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.

  13. Fast-ion-beam laser probing of ion-source energy distributions and atomic structure

    Energy Technology Data Exchange (ETDEWEB)

    Holt, Richard A., E-mail: rholt@uwo.ca; Rosner, S. David [University of Western Ontario, Physics and Astronomy Department (Canada)

    2013-04-15

    Collinear fast-ion-beam laser spectroscopy is a very high resolution probe for measuring ion-beam energy distributions and atomic structure parameters of interest in nuclear physics, atomic physics, and astrophysics. We have used offline 10-keV beams of atomic ions and a CW laser system to study the behavior of a Penning ion source and to measure hyperfine structure, isotope shifts, atomic lifetimes, spontaneous-emission branching fractions, oscillator strengths, and absolute wavelengths of a variety of atomic species from the lanthanide and transition-metal groups.

  14. 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.)

  15. 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...

  16. The effect of atoms excited by electron beam on metal evaporation

    CERN Document Server

    Xie Guo Feng; Ying Chun Tong

    2002-01-01

    In atomic vapor laser isotope separation (AVLIS), the metal is heated to melt by electron beams. The vapor atoms may be excited by electrons when flying through the electron beam. The excited atoms may be deexcited by inelastic collision during expansion. The electronic energy transfers translational energy. In order to analyse the effect of reaction between atoms and electron beams on vapor physical parameters, such as density, velocity and temperature, direct-simulation Monte Carlo method (DSMC) is used to simulate the 2-D gadolinium evaporation from long and narrow crucible. The simulation results show that the velocity and temperature of vapor increase, and the density decreases

  17. Emission of muonic tritium into vacuum: An atomic beam for muon experiments

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, M.C. [University of British Columbia (Canada); Bailey, J.M. [Chester Technology (United Kingdom); Beer, G.A. [University of Victoria (Canada); Beveridge, J.L. [TRIUMF (Canada); Douglas, J.L. [University of Victoria (Canada); Huber, T.M. [Gustavus Adolphus College (United States); Jacot-Guillarmod, R. [Universite de Fribourg, CH-1700 (Switzerland); Kammel, P. [University of California (United States); Kim, S.K. [Jeonbuk National University (Korea, Republic of); Knowles, P.E. [University of Victoria (Canada); Kunselman, A.R. [University of Wyoming (United States); Maier, M. [University of Victoria (Canada); Markushin, V.E. [Paul Scherrer Institute (Switzerland); Marshall, G.M. [TRIUMF (Canada); Martoff, C.J. [Temple University (United States); Mason, G.R. [University of Victoria (Canada); Mulhauser, F. [Universite de Fribourg, CH-1700 (Switzerland); Olin, A. [University of Victoria (Canada); Petitjean, C. [Paul Scherrer Institute (Switzerland); Porcelli, T.A. [University of Victoria (Canada)] (and others)

    1997-04-15

    The emission of muonic tritium atoms from a thin film of hydrogen isotopes into vacuum was observed. The time and position of the muon decays were measured by tracking the decay electron trajectory. The observations are useful both for testing the theoretical cross sections for muonic atomic interactions, and producing an atomic beam of slow {mu}{sup -}t with a controllable energy.

  18. 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

  19. 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.

  20. The quantum measurement effect of interaction without interaction for an atomic beam

    Directory of Open Access Journals (Sweden)

    Yong-Yi Huang

    Full Text Available When an atomic beam collectively and harmonically vibrates perpendicular to the wave vector of the beam, the number of atoms reaching the atomic detector will have a vibrant factor Δt/T if the measurement time interval Δt is shorter than the period T. This new quantum mechanical measurement effect for an atomic beam is called interaction without interaction: though the translational motion of the atomic beam does not interact with its collective and transverse harmonic vibration, the latter will have an effect on the measured number of atoms associated with the former. From the new measurement effect the classical harmonic vibration’s period is evaluated. We give a clear physical picture and a satisfactory physical interpretation for the measurement effect based on the Copenhagen interpretation of quantum mechanics. We present an experimental proposal to verify this measurement effect for an ion beam instead of an atomic beam. Keywords: The quantum measurement effect of interaction without interaction, The Copenhagen interpretation of quantum mechanics

  1. Summary of informal workshop on state of ion beam facilities for atomic physics research

    Energy Technology Data Exchange (ETDEWEB)

    Jones, K.W.; Cocke, C.L.; Datz, S.; Kostroun, V.

    1984-11-13

    The present state of ion beam facilities for atomic physics research in the United States is assessed by means of a questionnaire and informal workshop. Recommendations for future facilities are given. 3 refs.

  2. 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)

  3. Coherent and dynamic beam splitting based on light storage in cold atoms

    OpenAIRE

    Kwang-Kyoon Park; Tian-Ming Zhao; Jong-Chan Lee; Young-Tak Chough; Yoon-Ho Kim

    2016-01-01

    We demonstrate a coherent and dynamic beam splitter based on light storage in cold atoms. An input weak laser pulse is first stored in a cold atom ensemble via electromagnetically-induced transparency (EIT). A set of counter-propagating control fields, applied at a later time, retrieves the stored pulse into two output spatial modes. The high visibility interference between the two output pulses clearly demonstrates that the beam splitting process is coherent. Furthermore, by manipulating the...

  4. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. 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......(1 × 1) commensurate monolayer solid of H2/KCl(001). For the latter, there are cases where part of the incident beam is trapped in the interlayer region for times exceeding 50 ps, depending on the spacing between the monolayer and the substrate and on the angle of incidence. The feedback effect...

  6. Development Of Beam Position And Profile Monitor Based On Light Radiation Of Atoms Excited By The Beam Particles

    CERN Document Server

    Balalykin, N I; Brovko, O I; Bykovsky, V F; Dietrich, J; Kamerdzhiev, V; Meshkov, I N; Mohos, I; Parfenov, A N

    2004-01-01

    Particle beam position and profile monitor based on registration of the light radiated by residual gas atoms is being developed by collaboration JINR-Forschungszentrum Jülich. Proposed device and first experiments have been performed at Nuclotron (JINR) and COSY (FZJ) accelerators are presented in this report.

  7. 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.

  8. 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

  9. Entrainment of lithium atoms into a supersonic beam and magnetic deceleration

    Science.gov (United States)

    Lu, Yu; Gradl, Lukas; Ha, Lichung; Hillberry, Logan; Melin, Kevin; Nagornykh, Pavel; Zesch, Jordan; Raizen, Mark

    2017-04-01

    We report our progress on the development of an alternative to laser cooling of neutral atoms, using alkali atoms as the benchmark for a direct comparison. The first step is optimization of entrainment of lithium into a supersonic beam followed by magnetic deceleration. We create a supersonic beam of cold helium gas by pulsing on an Even-Lavie valve, which then crosses lithium vapor generated by a directional oven. The resulting entrainment number and temperature of the lithium atoms are measured downstream with a hot-wire detector. In order to further optimize entrainment, we developed a pulsed atomic source that is synchronized with the supersonic valve with an appropriate delay time. Lithium atoms from the directional oven accumulate on a thin metallic ribbon and are quickly evaporated as a short current pulse is applied, creating a dense plume of lithium vapor. The entrained lithium beam will be slowed by a magnetic decelerator as demonstrated in earlier work, combining all the components to deliver lithium atoms near rest in the laboratory frame. Atomic phase space density will be further increased by a new method that we recently proposed, which utilizes optical pumping and magnetic kicks, and does not rely on the momentum of the photon. W.M. Keck Foundation.

  10. ATOMIC AND MOLECULAR PHYSICS: Radiation forces on a three-level atom in the high-order Bessel beams

    Science.gov (United States)

    Wang, Zheng-Ling; Yin, Jian-Ping

    2008-07-01

    The general expressions of the average dissipative and dipole forces acting on a Λ-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 ħΓ(2κB) due to the orbital angular momentum lħ of the HBB.

  11. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Arikawa, Hiroshi, E-mail: arikawa@cyric.tohoku.ac.jp; Ando, S.; Aoki, T.; Ezure, S.; Harada, K.; Hayamizu, T.; Inoue, T.; Ishikawa, T.; Itoh, M.; Kawamura, H.; Kato, K.; Kato, T.; Uchiyama, A.; Sakemi, Y. [Cyclotron and Radioisotope Center, Tohoku University, Miyagi 980-8578 (Japan); Aoki, T. [Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902 (Japan); Furukawa, T. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Hatakeyama, A. [Department of Applied Physics, Tokyo University of Agriculture and Technology, Tokyo 184-8588 (Japan); Hatanaka, K.; Yoshida, H. P. [Research Center for Nuclear Physics, Osaka University, Osaka 606-8502 (Japan); Imai, K. [Advanced Science Research Center, Japan Atomic Energy Agency, Ibaraki 319-1184 (Japan); and others

    2014-02-15

    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 {sup 18}O 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.

  13. Velocity selective optical pumping effects on 85 Rb atoms from various coupling beam polarization configurations

    Science.gov (United States)

    Rehman, Hafeez Ur; Noh, Heung-Ryoul; Kim, Jin-Tae

    2017-11-01

    We have investigated velocity selective spectral profile variations of probe beam transmittance at Fg = 3 →Fe = 2 , 3, and 4 hyperfine manifolds of 85 Rb atoms along with coherence effects at the Fg = 3 →Fe = 4 transition with various coupling laser polarization configurations and a fixed probe polarization (σ+). Laser linewidth, atomic velocity distributions, frequency mixing of the coupling and probe laser beams between degenerate magnetic sublevels, and polarization variations of the coupling beam with the probe beam fixed at the Fg = 3 →Fe = 4 transition were used to simulate the line profiles. The calculated transmittance signals are in good agreement with observed signals for each coupling laser polarization configuration.

  14. Propagating of partially coherent laser beam in the near-resonant atomic gas

    Science.gov (United States)

    Kong, Delong; Wang, Zhaoying; Fang, Feiyun; Shi, Congquan; Lin, Qiang

    2017-09-01

    The characteristics of the light with various degrees of spatial coherence traveling in near-resonant atomic gas are investigated both experimentally and theoretically. The experimental results show that the coherence of partially coherent beams can get better after interaction with atoms under some certain conditions compared with that before interaction. The experimental results are explained theoretically by the method of spectroscopy absorption. Furthermore, partially coherent light has a better environmental adaptability than fully coherent light.

  15. Crossed Molecular Beam Study of the Reactions of Oxygen and Fluorine Atoms.

    Science.gov (United States)

    1980-03-01

    products (i.e., benzaldehyde , cresol, anisole, and benzyl alcohol). Supersonic beams of O(3 P) atoms produced in a radiofrequency dis- charge I0 and toluene ...used to clarify the reaction mechanism. The reaction of O(3p) with another aromatic hydrocarbon toluene , results in competition between two...substitution channels, loss of H atom and loss of CH5. In contrast to the 0 + C6H6 reaction, no stabilized oxygen- toluene adduct was observed., The development

  16. Atomic Beam Correlations and the Quantum State of the Micromaser

    CERN Document Server

    Elmfors, P; Skagerstam, B S; Elmfors, Per; Lautrup, Benny; Skagerstam, Bo Sture

    1997-01-01

    Correlation measurements on atoms having passed through a micromaser can be used to infer properties of the quantum state of the radiation field in the cavity. Long- (or short)-range correlations in time are associated with super- (or sub)-Poissonian photon statistics. In some realistic experimental situations the long-range correlations may reach a magnitude of many times the decay time of the cavity. Our assertions are verified by comparing theoretical calculations with a high-precision Monte Carlo simulation of the micromaser system.

  17. 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.

  18. Rubidium atomic beam clock based on lamp-pumping and fluorescence-detection scheme

    Science.gov (United States)

    Wang, Y. H.; Huang, J. Q.; Gu, Y.; Liu, S. Q.; Dong, T. Q.; Lu, Z. H.

    2011-02-01

    A compact, portable rubidium atomic beam clock based on lamp-pumping and fluorescence-detection scheme is proposed. The expected short-term frequency stability can be at least two orders of magnitude better than previous experimental results. The usages of lamp pumping, fluorescence detection and microwave slow-wave resonance structures make this design robust and compact.

  19. Coherent and dynamic beam splitting based on light storage in cold atoms.

    Science.gov (United States)

    Park, Kwang-Kyoon; Zhao, Tian-Ming; Lee, Jong-Chan; Chough, Young-Tak; Kim, Yoon-Ho

    2016-09-28

    We demonstrate a coherent and dynamic beam splitter based on light storage in cold atoms. An input weak laser pulse is first stored in a cold atom ensemble via electromagnetically-induced transparency (EIT). A set of counter-propagating control fields, applied at a later time, retrieves the stored pulse into two output spatial modes. The high visibility interference between the two output pulses clearly demonstrates that the beam splitting process is coherent. Furthermore, by manipulating the control lasers, it is possible to dynamically control the storage time, the power splitting ratio, the relative phase, and the optical frequencies of the output pulses. With further improvements, the active beam splitter demonstrated in this work might have applications in photonic photonic quantum information and in all-optical information processing.

  20. 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.

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

    Science.gov (United States)

    Hang, Chao; Huang, Guoxiang

    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.

  2. 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.

  3. Application of an atomic oxygen beam facility to the investigation of shuttle glow chemistry

    Science.gov (United States)

    Arnold, G. S.; Peplinski, D. R.

    1985-09-01

    A facility for the investigation of the interactions of energetic atomic oxygen with solids is described. The facility is comprised of a four chambered, differentially pumped molecular beam apparatus which can be equipped with one of a variety of sources of atomic oxygen. The primary source is a dc arc heated supersonic nozzle source which produces a flux of atomic oxygen in excess of 10 to the 15th power sq cm/sec at the target, at a velocity of 3.5 km/sec. Results of applications of this facility to the study of the reactions of atomic oxygen with carbon and polyimide films are briefly reviewed and compared to data obtained on various flights of the space shuttle. A brief discussion of possible application of this facility to investigation of chemical reactions which might contribute to atmosphere induced vehicle glow is presented.

  4. Discrete Energies of a Weakly Outcoupled Atom Laser Beam Outside the Bose–Einstein Condensate Region

    Directory of Open Access Journals (Sweden)

    Teguh Budi Prayitno

    2014-12-01

    Full Text Available We consider the possibility of a discrete set of energies of a weakly outcoupled atom laser beam to the homogeneous Schrödinger equation with anisotropic harmonic trap in Cartesian coordinates outside the Bose–Einstein condensate region. This treatment is used because working in the cylindrical coordinates is not really possible, even though we implement the cigar-shaped trap case. The Schrödinger equation appears to replace a set of two-coupled Gross– Pitaevskii equations by enabling the weak-coupling assumption. This atom laser can be produced in a simple way that only involves extracting the atoms in a condensate from by using the radio frequency field. We initially present the relation between condensates as sources and atom laser as an output by exploring the previous work of Riou et al. in the case of theoretical work for the propagation of atom laser beams. We also show that even though the discrete energies are obtained by means of an approaching harmonic oscillator, degeneracy is only available in two states because of the anisotropic external potential

  5. Pancakes, Waterbags, and Cold Atoms New Recipes for High-Brightness Electron Beams

    CERN Document Server

    Luiten, O J

    2005-01-01

    Ideal "waterbag" electron bunches - uniformly filled, hard-edged ellipsoids of charge - can be realized in practice by photoemission with properly shaped fs laser pulses [1]. The linear self-fields of such objects enable thermal-emittance-limited beams and bunch compression to the kA level. The thermal emittance may be lowered to below 0.1 micron by extracting the electrons from an ultra-cold plasma, created by photo-ionization of a cloud of laser-cooled atoms. We will present GPT simulations of the application of waterbags and cold atoms in realistic settings, based on established technology. The status of experiments will be reported.

  6. Applications of beam-foil spectroscopy to atomic collisions in solids

    Science.gov (United States)

    Sellin, I. A.

    1976-01-01

    Some selected papers presented at the Fourth International Conference on Beam-Foil Spectroscopy, whose results are of particular pertinence to ionic collision phenomena in solids, are reviewed. The topics discussed include solid target effects and means of surmounting them in the measurement of excited projectile ion lifetimes for low-energy heavy element ions; the electron emission accompanying the passage of heavy particles through solid targets; the collision broadening of X rays emitted from 100 keV ions moving in solids; residual K-shell excitation in chlorine ions penetrating carbon; comparison between 40 MeV Si on gaseous SiH4 targets at 300 mtorr and 40 MeV Si on Al; and the emergent surface interaction in beam-foil spectroscopy. A distinct overlap of interests between the sciences of beam-foil spectroscopy and atomic collisions in solids is pointed out.

  7. 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

  8. Atom trap for 221Fr from 225Ac ion beam implantation

    Science.gov (United States)

    Tandecki, M.; Behr, J. A.; Pearson, M. R.; Zhang, J.; Orozco, L.; Collister, R.; Gwinner, G.; Gomez, E.; Aubin, S.

    2012-10-01

    A neutral atom trap for francium parity violation experiments is being set up at TRIUMF. The half-lives of the longest isotopes are minutes, which mostly will be produced by the online mass separator of the ISAC facility. For systematic error studies for precision measurements, it can help to have a longer-lived source. ^221Fr is produced by t1/2=10 day ^225Ac α decay, and has been trapped at JILA [Z.-T. Lu PRL 79 994 (1997)]. Our approach would implant the mass-separated ^225Ac beam produced by ISAC at 1x10^7/s for a day after the production proton beam is turned off. The scheme to be tested: 30 keV ^225Ac beam is implanted in tantalum for a day; the sample is held in front of an yttrium foil (normally used to stop a mass-separated Fr beam) for 1 minute; 100 keV ^221Fr recoils escape and implant in the yttrium; tantalum is withdrawn, yttrium is moved to trap and heated; cycle repeats. First tests are planned for September, and one goal is precise measurements of atomic hyperfine splittings sensitive to the spatial distribution of nuclear magnetism.

  9. 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.)

  10. Modern Focused-Ion-Beam-Based Site-Specific Specimen Preparation for Atom Probe Tomography.

    Science.gov (United States)

    Prosa, Ty J; Larson, David J

    2017-04-01

    Approximately 30 years after the first use of focused ion beam (FIB) instruments to prepare atom probe tomography specimens, this technique has grown to be used by hundreds of researchers around the world. This past decade has seen tremendous advances in atom probe applications, enabled by the continued development of FIB-based specimen preparation methodologies. In this work, we provide a short review of the origin of the FIB method and the standard methods used today for lift-out and sharpening, using the annular milling method as applied to atom probe tomography specimens. Key steps for enabling correlative analysis with transmission electron-beam backscatter diffraction, transmission electron microscopy, and atom probe tomography are presented, and strategies for preparing specimens for modern microelectronic device structures are reviewed and discussed in detail. Examples are used for discussion of the steps for each of these methods. We conclude with examples of the challenges presented by complex topologies such as nanowires, nanoparticles, and organic materials.

  11. Substrate Dependent Ad-Atom Migration on Graphene and the Impact on Electron-Beam Sculpting Functional Nanopores.

    Science.gov (United States)

    Freedman, Kevin J; Goyal, Gaurav; Ahn, Chi Won; Kim, Min Jun

    2017-05-10

    The use of atomically thin graphene for molecular sensing has attracted tremendous attention over the years and, in some instances, could displace the use of classical thin films. For nanopore sensing, graphene must be suspended over an aperture so that a single pore can be formed in the free-standing region. Nanopores are typically drilled using an electron beam (e-beam) which is tightly focused until a desired pore size is obtained. E-beam sculpting of graphene however is not just dependent on the ability to displace atoms but also the ability to hinder the migration of ad-atoms on the surface of graphene. Using relatively lower e-beam fluxes from a thermionic electron source, the C-atom knockout rate seems to be comparable to the rate of carbon ad-atom attraction and accumulation at the e-beam/graphene interface (i.e., R knockout ≈ R accumulation ). Working at this unique regime has allowed the study of carbon ad-atom migration as well as the influence of various substrate materials on e-beam sculpting of graphene. We also show that this information was pivotal to fabricating functional graphene nanopores for studying DNA with increased spatial resolution which is attributed to atomically thin membranes.

  12. 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.)

  13. Control of RILIS lasers at IGISOL facilities using a compact atomic beam reference cell

    Energy Technology Data Exchange (ETDEWEB)

    Kron, T., E-mail: kron@uni-mainz.de [Johannes Gutenberg-Universitaet Mainz, Institut fuer Physik (Germany); Ferrer-Garcia, R. [KU Leuven, Instituut voor Kern- en Stralingsfysica (Belgium); Lecesne, N. [GANIL, CEA/DSM-CNRS/IN2P3 (France); Sonnenschein, V. [University of Jyvaeskylae, Department of Physics (Finland); Raeder, S. [TRIUMF - Canada' s National Laboratory for Nuclear and Particle Physics (Canada); Rossnagel, J.; Wendt, K. [Johannes Gutenberg-Universitaet Mainz, Institut fuer Physik (Germany)

    2013-04-15

    The choice and proper operation of the laser systems for laser ion sources at on-line facilities using multi-step resonance ionization processes is the basis for production of intense and pure radioactive ion beams. These pave the way for numerous fundamental studies in nuclear and astrophysics. A comparison between systems of medium or high repetition rate pulsed tunable lasers based on dyes or crystals as active medium has been carried out at the IGISOL facility at Louvain-la-Neuve. The importance of properly controlling the operation conditions of the individual lasers via a reference atomic beam chamber is highlighted and design and implementation of such a compact device for permanent monitoring as well as possible regulation of the various laser parameters of relevance is discussed.

  14. ARTICLE Crossed Beams Study on the Dynamics of F Atom Reaction with 1,2-Butadiene

    Science.gov (United States)

    Xiao, Chong-fa; Shen, Guan-lin; Wang, Xiu-yan; Yang, Xue-ming

    2010-12-01

    We have investigated the dynamics of the F+C4H6 reaction using the universal crossed molecular beam method. The C4H5F+H reaction channel was observed in this experiment. Angular resolved time-of-flight spectra have been measured for the C4H5F product. Product angular distributions as well as kinetic energy distributions were determined for this product channel. Experimental results show that the C4H5F product is largely backward scattered with considerable forward scattering signal, relative to the F atom beam direction. This suggests that the reaction channel mainly proceeds via a long-lived complex formation mechanism, with possible contribution from a direct SN2 type mechanism.

  15. 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.

    2016-01-01

    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 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. PMID:27239245

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

    Energy Technology Data Exchange (ETDEWEB)

    McClelland, J. J.; Wilson, T. M. [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Steele, A. V.; Knuffman, B.; Schwarzkopf, A. [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); zeroK NanoTech, Gaithersburg, Maryland 20878 (United States); Twedt, K. A. [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Maryland Nanocenter, University of Maryland, College Park, Maryland 20742 (United States)

    2016-03-15

    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{sup +} 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.

  17. High quality atomically thin PtSe2 films grown by molecular beam epitaxy

    Science.gov (United States)

    Yan, Mingzhe; Wang, Eryin; Zhou, Xue; Zhang, Guangqi; Zhang, Hongyun; Zhang, Kenan; Yao, Wei; Lu, Nianpeng; Yang, Shuzhen; Wu, Shilong; Yoshikawa, Tomoki; Miyamoto, Koji; Okuda, Taichi; Wu, Yang; Yu, Pu; Duan, Wenhui; Zhou, Shuyun

    2017-12-01

    Atomically thin PtSe2 films have attracted extensive research interests for potential applications in high-speed electronics, spintronics and photodetectors. Obtaining high quality thin films with large size and controlled thickness is critical. Here we report the first successful epitaxial growth of high quality PtSe2 films by molecular beam epitaxy. Atomically thin films from 1 ML to 22 ML have been grown and characterized by low-energy electron diffraction, Raman spectroscopy and x-ray photoemission spectroscopy. Moreover, a systematic thickness dependent study of the electronic structure is revealed by angle-resolved photoemission spectroscopy (ARPES), and helical spin texture is revealed by spin-ARPES. Our work provides new opportunities for growing large size single crystalline films to investigate the physical properties and potential applications of PtSe2.

  18. 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.

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

    Science.gov (United States)

    Herman, Zdenek

    2013-07-01

    Single-electron transfer reactions in collisions of atomic and molecular doubly charged ions, with atoms and molecules, were investigated in a series of crossed-beam scattering, translational spectroscopy and product luminescence experiments. Investigation of a series of atomic dication-atom electron transfer at collision energies of 0.1-10 eV provided data on differential and relative total cross sections of state-to-state processes. Populations of electronic and vibrational states and rotational temperatures of molecular product ions were obtained from studies of non-dissociative electron transfer in systems containing simple molecular dications and/or molecular targets. The product electronic states populated with highest probability were those for which the translational energy release was 3-5 eV, indicating that the 'reaction window' concept, based on the Landau-Zener formalism, is applicable also to molecular systems. Population of the vibrational states of the molecular products could be described by Franck-Condon factors of the vertical transitions between the reactant and product states, especially at higher (keV) collision energies. Rotational temperature of the product molecular cations was found to be surprisingly low, mostly 400-500 K, practically the temperature of the ion source.

  20. Local enhancement of radiation dose by using high atomic number materials with high energy photon beam

    Science.gov (United States)

    Alkhatib, Ahmad Khaled

    The goal of treatment planning in radiation therapy is to maximize the absorbed dose in abnormal cells and minimize the dose in normal cells. It is long established that the probability of pair production interactions (converting photon to electron and positron see chapter II) increases with the increase of the photon energy above a 1.02 MV threshold and with the square of the atomic number of the medium. In this work I tried to locally enhance the absorbed dose by using both a high energy photon beam and high Z material (Gold foils), to observe the effect of the secondary electrons that are produced in the high z material (gold) with high energy photons (end point energy 25MV). To observe the range of these secondary electrons, I changed the gap between two gold foils. I studied also the effect of varying the thickness of both gold foils. To verify the dependence of the atomic number (Z) I repeated the measurements with two Aluminum foils, and to observe the effect of The Higher photon energy I used a range of photon beams with end point energies 6, 10, 15, 18 and 25 MV. I used Monte Carlo code to confirm the result. The calculated dose enhancements from the simulation were in general 5% higher the measured values.

  1. 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.)

  2. 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.

  3. Electron-beam-induced carbon contamination on silicon: characterization using Raman spectroscopy and atomic force microscopy.

    Science.gov (United States)

    Lau, Deborah; Hughes, Anthony E; Muster, Tim H; Davis, Timothy J; Glenn, A Matthew

    2010-02-01

    Electron-beam-induced carbon film deposition has long been recognized as a side effect of scanning electron microscopy. To characterize the nature of this type of contamination, silicon wafers were subjected to prolonged exposure to 15 kV electron beam energy with a probe current of 300 pA. Using Raman spectroscopy, the deposited coating was identified as an amorphous carbon film with an estimated crystallite size of 125 A. Using atomic force microscopy, the cross-sectional profile of the coating was found to be raised and textured, indicative of the beam raster pattern. A map of the Raman intensity across the coating showed increased intensity along the edges and at the corner of the film. The intensity profile was in excess of that which could be explained by thickness alone. The enhancement was found to correspond with a modeled local field enhancement induced by the coating boundary and showed that the deposited carbon coating generated a localized disturbance in the opto-electrical properties of the substrate, which is compared and contrasted with Raman edge enhancement that is produced by surface structure in silicon.

  4. Environmental sensing with optical fiber sensors processed with focused ion beam and atomic layer deposition

    Science.gov (United States)

    Flores, Raquel; Janeiro, Ricardo; Dahlem, Marcus; Viegas, Jaime

    2015-03-01

    We report an optical fiber chemical sensor based on a focused ion beam processed optical fiber. The demonstrated sensor is based on a cavity formed onto a standard 1550 nm single-mode fiber by either chemical etching, focused ion beam milling (FIB) or femtosecond laser ablation, on which side channels are drilled by either ion beam milling or femtosecond laser irradiation. The encapsulation of the cavity is achieved by optimized fusion splicing onto a standard single or multimode fiber. The empty cavity can be used as semi-curved Fabry-Pérot resonator for gas or liquid sensing. Increased reflectivity of the formed cavity mirrors can be achieved with atomic layer deposition (ALD) of alternating metal oxides. For chemical selective optical sensors, we demonstrate the same FIB-formed cavity concept, but filled with different materials, such as polydimethylsiloxane (PDMS), poly(methyl methacrylate) (PMMA) which show selective swelling when immersed in different solvents. Finally, a reducing agent sensor based on a FIB formed cavity partially sealed by fusion splicing and coated with a thin ZnO layer by ALD is presented and the results discussed. Sensor interrogation is achieved with spectral or multi-channel intensity measurements.

  5. Observation of spontaneously generated coherence on absorption in rubidium atomic beam

    Science.gov (United States)

    Tian, Si-Cong; Kang, Zhi-Hui; Wang, Chun-Liang; Wan, Ren-Gang; Kou, Jun; Zhang, Hang; Jiang, Yun; Cui, Hai-Ning; Gao, Jin-Yue

    2012-02-01

    We report the experimental observation of the effect of spontaneously generated coherence on absorption without the rigorous requirement of close-lying levels. The experiments are studied in both a four-level N-type and a four-level inverted-Y-type atomic system in a rubidium atomic beam. With the coupling and controlling field, the N-type system is equivalent to a system with three closely upper levels coupled to one lower level by the same vacuum modes. The quantum interference can induce two prominent and nearly transparent holes where the slope of the refractive index is very steep. This special situation could allow the simultaneous propagation of two weak pulses with different frequencies. When we tune the wavelength of the controlling field, the N-type system turns to be the inverted-Y atomic system. Under the two-photon resonance condition, the system is equivalent to a V-type system with two closely upper levels, and the interference can reduce one broad transparency window in the middle of the absorption spectrum. Besides we can control the number of the spontaneously decay channels by the detuning of the controlling field, thus the effect of spontaneously generated coherence can exist in three or two closely space levels.

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

    Energy Technology Data Exchange (ETDEWEB)

    Karam, J-C [Laboratoire de Physique des Lasers (UMR-CNRS 7538), Universite Paris 13 99, Av. J.B. Clement, 93430-Villetaneuse (France); Grucker, J [Laboratoire de Physique des Lasers (UMR-CNRS 7538), Universite Paris 13 99, Av. J.B. Clement, 93430-Villetaneuse (France); Boustimi, M [Laboratoire de Physique des Lasers (UMR-CNRS 7538), Universite Paris 13 99, Av. J.B. Clement, 93430-Villetaneuse (France); Bocvarski, V [Institute of Physics, Pregrevica, Zemun, Belgrade (Serbia and Montenegro); Vassilev, G [Laboratoire de Physique des Lasers (UMR-CNRS 7538), Universite Paris 13 99, Av. J.B. Clement, 93430-Villetaneuse (France); Reinhardt, J [Laboratoire de Physique des Lasers (UMR-CNRS 7538), Universite Paris 13 99, Av. J.B. Clement, 93430-Villetaneuse (France); Mainos, C [Laboratoire de Physique des Lasers (UMR-CNRS 7538), Universite Paris 13 99, Av. J.B. Clement, 93430-Villetaneuse (France); Perales, F [Laboratoire de Physique des Lasers (UMR-CNRS 7538), Universite Paris 13 99, Av. J.B. Clement, 93430-Villetaneuse (France); Baudon, J [Laboratoire de Physique des Lasers (UMR-CNRS 7538), Universite Paris 13 99, Av. J.B. Clement, 93430-Villetaneuse (France); Robert, J [Laboratoire de Physique des Lasers (UMR-CNRS 7538), Universite Paris 13 99, Av. J.B. Clement, 93430-Villetaneuse (France); Ducloy, Martial [Laboratoire de Physique des Lasers (UMR-CNRS 7538), Universite Paris 13 99, Av. J.B. Clement, 93430-Villetaneuse (France)

    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.

  7. Fluorescence detection of white-beam X-ray absorption anisotropy: towards element-sensitive projections of local atomic structure

    Science.gov (United States)

    Korecki, P.; Tolkiehn, M.; Dąbrowski, K. M.; Novikov, D. V.

    2011-01-01

    Projections of the atomic structure around Nb atoms in a LiNbO3 single crystal were obtained from a white-beam X-ray absorption anisotropy (XAA) pattern detected using Nb K fluorescence. This kind of anisotropy results from the interference of X-rays inside a sample and, owing to the short coherence length of a white beam, is visible only at small angles around interatomic directions. Consequently, the main features of the recorded XAA corresponded to distorted real-space projections of dense-packed atomic planes and atomic rows. A quantitative analysis of XAA was carried out using a wavelet transform and allowed well resolved projections of Nb atoms to be obtained up to distances of 10 Å. The signal of nearest O atoms was detected indirectly by a comparison with model calculations. The measurement of white-beam XAA using characteristic radiation indicates the possibility of obtaining element-sensitive projections of the local atomic structure in more complex samples. PMID:21997909

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

    Science.gov (United States)

    Labuda, Aleksander; Proksch, Roger

    2015-06-01

    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.

  10. 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.

  11. Atom beam sputtered Ag-TiO{sub 2} plasmonic nanocomposite thin films for photocatalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jaspal; Sahu, Kavita [School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, NewDelhi 110078 (India); Pandey, A. [Solid State Physics Laboratory, Defence Research and Development Organization, Timarpur, Delhi 110054 (India); Kumar, Mohit [Institute of Physics, Sachivalaya Marg, Bhubaneswar, Odisha 751005 (India); Ghosh, Tapas; Satpati, B. [Saha Institute of Nuclear Physics, HBNI, 1/AF, Bidhannagar, Kolkata 700064 (India); Som, T.; Varma, S. [Institute of Physics, Sachivalaya Marg, Bhubaneswar, Odisha 751005 (India); Avasthi, D.K. [Amity Institute of Nanotechnology, Noida 201313, Uttar Pradesh (India); Mohapatra, Satyabrata, E-mail: smiuac@gmail.com [School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, NewDelhi 110078 (India)

    2017-07-31

    The development of nanocomposite coatings with highly enhanced photocatalytic activity is important for photocatalytic purification of water and air. We report on the synthesis of Ag-TiO{sub 2} nanocomposite thin films with highly enhanced photocatalytic activity by atom beam co-sputtering technique. The effects of Ag concentration on the structural, morphological, optical, plasmonic and photocatalytic properties of the nanocomposite thin films were investigated. UV–visible DRS studies revealed the presence of surface plasmon resonance (SPR) peak characteristic of Ag nanoparticles together with the excitonic absorption peak originating from TiO{sub 2} nanoparticles in the nanocomposites. XRD studies showed that the nanocomposite thin films consist of Ag nanoparticles and rutile TiO{sub 2} nanoparticles. The synthesized Ag-TiO{sub 2} nanocomposite thin films with 5 at% Ag were found to exhibit highly enhanced photocatalytic activity for sun light driven photocatalytic degradation of methylene blue in water, indicating their potential application in water purification.

  12. Chemical states of localized Fe atoms in ethylene matrices using in-beam Mössbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Y., E-mail: kyoshio@pc.uec.ac.jp [University of Electro-Communications, Graduate School of Engineering Science (Japan); Yamada, Y. [Tokyo University of Science, Department of Chemistry (Japan); Tanigawa, S. [University of Electro-Communications, Graduate School of Engineering Science (Japan); Mihara, M. [Osaka University, Graduate School of Science (Japan); Kubo, M. K. [International Christian University, Division of Arts and Sciences (Japan); Sato, W. [Kanazawa University, Institute of Science and Engineering (Japan); Miyazaki, J. [Tokyo University of Agriculture and Technology, Department of Chemical Engineering (Japan); Nagatomo, T. [RIKEN, Nishina Center for Accelerator-Based Science (Japan); Sato, Y.; Natori, D.; Suzuki, M. [University of Electro-Communications, Graduate School of Engineering Science (Japan); Kobayashi, J. [International Christian University, Division of Arts and Sciences (Japan); Sato, S.; Kitagawa, A. [National Institute of Radiological Science (Japan)

    2016-12-15

    The reaction products of isolated single iron atoms in a low concentration matrix of ethylene were studied using in-beam Mössbauer spectroscopy with a short-lived {sup 57}Mn (T{sub 1/2}=1.45 m) beam. The in-beam Mössbauer spectrum of {sup 57}Fe arising from {sup 57}Mn in a matrix of ethylene and argon measured at 16 K was analyzed with four components. Density functional theory calculations were carried out to confirm the assignments. It was suggested that the reaction produced monoiron species of Fe(C {sub 2}H{sub 4}) with a spin state of S = 2.

  13. 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.

  14. Two-stage crossed beam cooling with ⁶Li and ¹³³Cs atoms in microgravity.

    Science.gov (United States)

    Luan, Tian; Yao, Hepeng; Wang, Lu; Li, Chen; Yang, Shifeng; Chen, Xuzong; Ma, Zhaoyuan

    2015-05-04

    Applying the direct simulation Monte Carlo (DSMC) method developed for ultracold Bose-Fermi mixture gases research, we study the sympathetic cooling process of 6Li and 133Cs atoms in a crossed optical dipole trap. The obstacles to producing 6Li Fermi degenerate gas via direct sympathetic cooling with 133Cs are also analyzed, by which we find that the side-effect of the gravity is one of the main obstacles. Based on the dynamic nature of 6Li and 133Cs atoms, we suggest a two-stage cooling process with two pairs of crossed beams in microgravity environment. According to our simulations, the temperature of 6Li atoms can be cooled to T = 29.5 pK and T/TF = 0.59 with several thousand atoms, which propose a novel way to get ultracold fermion atoms with quantum degeneracy near pico-Kelvin.

  15. Laser sustained discharge nozzle apparatus for the production of an intense beam of high kinetic energy atomic species

    Science.gov (United States)

    Cross, Jon B.; Cremers, David A.

    1988-01-01

    Laser sustained discharge apparatus for the production of intense beams of high kinetic energy atomic species. A portion of the plasma resulting from a laser sustained continuous optical discharge which generates energetic atomic species from a gaseous source thereof is expanded through a nozzle into a region of low pressure. The expanded plasma contains a significant concentration of the high kinetic energy atomic species which may be used to investigate the interaction of surfaces therewith. In particular, O-atoms having velocities in excess of 3.5 km/s can be generated for the purpose of studying their interaction with materials in order to develop protective materials for spacecraft which are exposed to such energetic O-atoms during operation in low earth orbit.

  16. 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.

  17. Augmenting the bioactivity of polyetheretherketone using a novel accelerated neutral atom beam technique.

    Science.gov (United States)

    Ajami, S; Coathup, M J; Khoury, J; Blunn, G W

    2017-08-01

    Polyetheretherketone (PEEK) is an alternative to metallic implants in orthopedic applications; however, PEEK is bioinert and does not osteointegrate. In this study, an accelerated neutral atom beam technique (ANAB) was employed to improve the bioactivity of PEEK. The aim was to investigate the growth of human mesenchymal stem cells (hMSCs), human osteoblasts (hOB), and skin fibroblasts (BR3G) on PEEK and ANAB PEEK. The surface roughness and contact angle of PEEK and ANAB PEEK was measured. Cell metabolic activity, proliferation and alkaline phosphatase (ALP) was measured and cell attachment was determined by quantifying adhesion plaques with cells. ANAB treatment increased the surface hydrophilicity [91.74 ± 4.80° (PEEK) vs. 74.82 ± 2.70° (ANAB PEEK), p PEEK compared to PEEK (p PEEK surfaces. MSCs seeded on ANAB PEEK in the presence of osteogenic media, expressed increased levels of ALP compared to untreated PEEK (p PEEK. ANAB treatment may improve the osteointegration of PEEK implants. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1438-1446, 2017. © 2016 Wiley Periodicals, Inc.

  18. Enhanced bioactivity and osseointegration of PEEK with accelerated neutral atom beam technology.

    Science.gov (United States)

    Khoury, Joseph; Maxwell, Melissa; Cherian, Raymond E; Bachand, James; Kurz, Arthur C; Walsh, Michael; Assad, Michel; Svrluga, Richard C

    2017-04-01

    Polyetheretherketone (PEEK) is growing in popularity for orthopedic, spinal, and trauma applications but has potential significant limitations in use. PEEK is biocompatible, similar in elasticity to bone, and radiolucent, but is inert and therefore does not integrate well with bone. Current efforts are focusing on increasing the bioactivity of PEEK with surface modifications to improve the bone-implant interface. We used a novel Accelerated Neutral Atom Beam (ANAB) technology to enhance the bioactivity of PEEK. Human osteoblast-like cells seeded on ANAB-treated PEEK result in significantly enhanced proliferation compared with control PEEK. Cells grown on ANAB-treated PEEK increase osteogenic expression of ALPL (1.98-fold, p PEEK implants resulted in enhanced bone-in-contact by 3.09-fold (p PEEK has the potential to enhance its bioactivity, leading to bone formation and significantly decreasing osseointegration time of orthopedic and spinal implants. ANAB treatment, therefore, may significantly enhance the performance of PEEK medical implants and lead to improved clinical outcomes. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 531-543, 2017. © 2015 Wiley Periodicals, Inc.

  19. 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.

  20. Characteristics of The Narrow Spectrum Beams Used in the Secondary Standard Dosimetry Laboratory at the Lebanese Atomic Energy Commission.

    Science.gov (United States)

    Melhem, N; El Balaa, H; Younes, G; Al Kattar, Z

    2017-06-15

    The Secondary Standard Dosimetry Laboratory at the Lebanese Atomic Energy Commission has different calibration methods for various types of dosimeters used in industrial, military and medical fields. The calibration is performed using different beams of X-rays (low and medium energy) and Gamma radiation delivered by a Cesium 137 source. The Secondary Standard Dosimetry laboratory in charge of calibration services uses different protocols for the determination of high and low air kerma rate and for narrow and wide series. In order to perform this calibration work, it is very important to identify all the beam characteristics for the different types of sources and qualities of radiation. The following work describes the methods used for the determination of different beam characteristics and calibration coefficients with their uncertainties in order to enhance the radiation protection of workers and patient applications in the fields of medical diagnosis and industrial X-ray. All the characteristics of the X-ray beams are determined for the narrow spectrum series in the 40 and 200 keV range where the inherent filtration, the current intensity, the high voltage, the beam profile and the total uncertainty are the specific characteristics of these X-ray beams. An X-ray software was developed in order to visualize the reference values according to the characteristics of each beam. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Holst, B.; Piskur, J. [Department of Physics and Technology, University of Bergen, Allegaten 55, 5007 Bergen (Norway); Kostrobiy, P.P.; Markovych, B.M. [Department of Applied Mathematics, Lviv National University of Technology, Stefan Bandera Str. 12, UA-79013 Lviv (Ukraine); Suchorski, Y., E-mail: yuri.suchorski@imc.tuwien.ac.at [Vienna University of Technology, Veterinaerplatz 1, A-1210 Vienna (Austria)

    2009-04-15

    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 {sigma}{sub eff} 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 {sigma}{sub eff} 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.

  3. High-speed, two-dimensional synchrotron white-beam x-ray radiography of spray breakup and atomization

    Energy Technology Data Exchange (ETDEWEB)

    Halls, Benjamin R.; Radke, Christopher D.; Reuter, Benjamin J.; Kastengren, Alan L.; Gord, James R.; Meyer, Terrence R.

    2017-01-01

    High-speed, two-dimensional synchrotron x-ray radiography and phase-contrast imaging are demonstrated in propulsion sprays. Measurements are performed at the 7-BM beamline at the Advanced Photon Source user facility at Argonne National Laboratory using a recently developed broadband x-ray white beam. This novel enhancement allows for high speed, high fidelity x-ray imaging for the community at large. Quantitative path-integrated liquid distributions and spatio-temporal dynamics of the sprays were imaged with a LuAG:Ce scintillator optically coupled to a high-speed CMOS camera. Images are collected with a microscope objective at frame rates of 20 kHz and with a macro lens at 120 kHz, achieving spatial resolutions of 12 μm and 65 μm, respectively. Imaging with and without potassium iodide (KI) as a contrast-enhancing agent is compared, and the effects of broadband attenuation and spatial beam characteristics are determined through modeling and experimental calibration. In addition, phase contrast is used to differentiate liquid streams with varying concentrations of KI. The experimental approach is applied to different spray conditions, including quantitative measurements of mass distribution during primary atomization and qualitative visualization of turbulent binary fluid mixing. High-speed, two-dimensional synchrotron white-beam x-ray radiography of spray breakup and atomization. Available from: https://www.researchgate.net/publication/312567827_High-speed_two-dimensional_synchrotron_white-beam_x-ray_radiography_of_spray_breakup_and_atomization [accessed Aug 31, 2017].

  4. Precision spectroscopy of the 2S-4P{sub 1/2} transition in atomic hydrogen on a cold thermal beam of optically excited 2S atoms

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Axel; Kolachevsky, Nikolai; Alnis, Janis; Yost, Dylan C.; Matveev, Arthur; Parthey, Christian G.; Pohl, Randolf; Udem, Thomas [Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany); Khabarova, Ksenia [FSUE ' VNIIFTRI' , 141570 Moscow (Russian Federation); Haensch, Theodor W. [Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany); Ludwig-Maximilians-Universitaet, 80799 Muenchen (Germany)

    2013-07-01

    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-4P{sub 1/2} 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.

  5. Spectroscopic determination of electron energies in a discharge of atomic H produced by a monoenergetic electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Kipritidis, J; Fitzgerald, M; Khachan, J [Applied and Plasma Physics Group, School of Physics A28, University of Sydney, NSW 2006 (Australia)

    2007-09-07

    We construct a collisional-radiative model for atomic H produced in H{sub 2} gas at units and tens of mTorr pressures by a monoenergetic electron beam at units of keV energies. Unlike similar work in regimes of higher pressure and lower electron energies, we calculate the electron energy dependence of the two strongest Balmer lines (H{sub {alpha}} and H{sub {beta}}). A key result is that the intensity ratios do not uniquely specify the electron energy, and so we propose a new method for measurement of the spatial energy profile using the absolute and relative intensities in tandem. The model shows qualitative agreement with semi-empirical distributions of absolute and relative intensities versus electron energy for beams emerging from a biconical hollow cathode.

  6. Depolarization of the 4{sup 1}D{sub 2} state of a helium atom by charged particles in beam plasma discharge

    Energy Technology Data Exchange (ETDEWEB)

    Kazantsev, S.A.; Luchinkina, V.V.; Mezentsev, A.P.; Mustafaev, A.S.; Rebane, V.N.; Rys, A.G.; Stepanov, Yu.L. [St. Petersburg (Russian Federation)

    1994-06-01

    Depolarization of the 4{sup 1}D{sub 2}-2{sup 1}P{sub 1} spectra line of He atoms caused by collisions with charged particles in beam plasma discharge is investigated both experimentally and theoretically. A comparison is made between the values of the rate constant for the collisional breakdown of alignment of helium atoms in the 4{sup 1}D{sub 2} state calculated from the theory of collisional relaxation of atomic polarization moments and determined from the experimentally observed broadening of the Hanle signal contour with the increase of the beam discharge current. 23 refs., 6 figs.

  7. Atomic radical abatement of organic impurities from electron beam deposited metallic structures

    NARCIS (Netherlands)

    Wnuk, J.D.; Gorham, J.M.; Rosenberg, S.G.; Madey, T.E.; Hagen, C.W.; Fairbrother, D.H.

    2010-01-01

    Focused electron beam induced processing (FEBIP) of volatile organometallic precursors has become an effective and versatile method of fabricating metal-containing nanostructures. However, the electron stimulated decomposition process responsible for the growth of these nanostructures traps much of

  8. An atomic hydrogen beam to test ASACUSA's apparatus for antihydrogen spectroscopy

    CERN Document Server

    Diermaier, Martin; Kolbinger, Bernadette; Malbrunot, Chloé; Massiczek, Oswald; Sauerzopf, Clemens; Simon, Martin C.; Wolf, Michael; Zmeskal, Johann; Widmann, Eberhard

    2015-01-01

    The ASACUSA collaboration aims to measure the ground state hyperfine splitting (GS-HFS) of antihydrogen, the antimatter pendant 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.

  9. 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)

  10. 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 ...

  11. Effects of co-implanted oxygen or aluminum atoms on hydrogen migration and damage structure in multiple-beam irradiated Al sub 2 O sub 3

    CERN Document Server

    Katano, Y; Yamamoto, S; Nakazawa, T; Yamaki, D; Noda, K

    2000-01-01

    Depth profiles of implanted H atoms were measured for single crystalline Al sub 2 O sub 3 samples irradiated at 923 K with dual or triple beams of 0.25 MeV H-, 0.6 MeV He-, 2.4 MeV O-ions or 2.6 MeV Al-ions. The peaks occur at 1.55 and 1.45 mu m in the depth profiles measured for the H + Al dual beam irradiation and H + O dual beam case, respectively. The ratio of the peak areas is over 4, which is much larger than the implanted H atom ratio of 1.1, indicating that implanted Al atoms suppress the mobility of H atoms. However, the ratio becomes almost 1 between the triple beam samples with H + He + O-ions and with H + He + Al-ions at comparable doses. The fact demonstrates that implanted He atoms overwhelm the effects of the implanted self-cation/anion excess atoms on the migration behaviors of implanted hydrogen and radiation produced point defects, with the resulting sluggish cavity growth observed.

  12. Development of a compact thermal lithium atom beam source for measurements of electron velocity distribution function anisotropy in electron cyclotron resonance plasmas.

    Science.gov (United States)

    Nishioka, T; Shikama, T; Nagamizo, S; Fujii, K; Zushi, H; Uchida, M; Iwamae, A; Tanaka, H; Maekawa, T; Hasuo, M

    2013-07-01

    The anisotropy of the electron velocity distribution function (EVDF) in plasmas can be deduced from the polarization of emissions induced by anisotropic electron-impact excitation. In this paper, we develop a compact thermal lithium atom beam source for spatially resolved measurements of the EVDF anisotropy in electron cyclotron resonance (ECR) plasmas. The beam system is designed such that the ejected beam has a slab shape, and the beam direction is variable. The divergence and flux of the beam are evaluated by experiments and calculations. The developed beam system is installed in an ECR plasma device with a cusp magnetic field, and the LiI 2s-2p emission (670.8 nm) is observed in low-pressure helium plasma. The two-dimensional distributions of the degree and direction of the polarization in the LiI emission are measured by a polarization imaging system. The evaluated polarization distribution suggests the spatial variation of the EVDF anisotropy.

  13. Interfacial characteristics of Y2O3/GaSb(001) grown by molecular beam epitaxy and atomic layer deposition

    Science.gov (United States)

    Lin, Y. H.; Lin, K. Y.; Hsueh, W. J.; Young, L. B.; Chang, T. W.; Chyi, J. I.; Pi, T. W.; Kwo, J.; Hong, M.

    2017-11-01

    High quality Y2O3 on GaSb was achieved using both molecular beam epitaxy (MBE) and atomic layer deposition (ALD) with interfacial characteristics studied by in-situ X-ray photoelectron spectroscopy (XPS) and metal-oxide-semiconductor (MOS) electrical measurements. Ga-oxide and stoichiometric Sb-oxides were obtained in the MBE-Y2O3/GaSb and non-stoichiometric Sb2Ox (x<4) was found in the ALD-Y2O3/GaSb according to the XPS spectra. From the capacitance-voltage (CV) measurements, MBE-Y2O3 provides lower interfacial trap density (Dit) grown at elevated temperature of 200°C, while ALD-grown Y2O3 shows smaller hysteresis and higher dielectric constant.

  14. Resonant Formation of d{mu}t Molecules in Deuterium: An Atomic Beam Measurement of Muon Catalyzed dt Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, M. C. [Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 2A6 (Canada); TRIUMF, Vancouver, Canada V6T 2A3 (Canada); Adamczak, A. [Institute of Nuclear Physics, 31-342 Krakow, (Poland); Bailey, J. M. [Chester Technology, Chester CH4 7QH (United Kingdom); Beer, G. A. [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, Canada V8W 2Y2 (Canada); Beveridge, J. L. [TRIUMF, Vancouver, Canada V6T 2A3 (Canada); Faifman, M. P. [Russian Research Center, Kurchatov Institute, Moscow 123182, Russia (Russian Federation); Huber, T. M. [Department of Physics, Gustavus Adolphus College, St. Peter, Minnesota 56082 (United States); Kammel, P. [Department of Physics and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Kim, S. K. [Department of Physics, Jeonbuk National University, Jeonju City 560-756, Korea (Korea, Republic of); Knowles, P. E. [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, Canada V8W 2Y2 (Canada)] (and others)

    2000-08-21

    Resonant formation of d{mu}t molecules in collisions of muonic tritium ({mu}t ) on D{sub 2} was investigated using a beam of {mu}t atoms, demonstrating a new direct approach in muon catalyzed fusion studies. Strong epithermal resonances in d{mu}t formation were directly revealed for the first time. >From the time-of-flight analysis of 2036{+-}116 dt fusion events, a formation rate consistent with 0.73{+-}(0.16){sub meas}{+-} (0.09){sub model} times the theoretical prediction was obtained. For the largest peak at a resonance energy of 0.423{+-}0.037 eV , this corresponds to a rate of (7.1{+-}1.8)x10{sup 9} s{sup -1} , more than an order of magnitude larger than those at low energies. (c) 2000 The American Physical Society.

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

    NARCIS (Netherlands)

    Irimia, D.; Dobrikov, D.; Kortekaas, R.; Voet, H.; Ende, D.A. van den; Groen, W.A.; Janssen, M.H.M.

    2009-01-01

    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

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

    NARCIS (Netherlands)

    Irimia, D.; Dobrikov, D.H.; Kortekaas, R.; van der Voet, H.; van den Ende, D.A.; Groen, W.E.; Janssen, M.H.M.

    2009-01-01

    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

  17. Dispersion in a four level N-scheme atomic system with co- and counter- propagating beams

    Science.gov (United States)

    Davis, J. P.; Narducci, F. A.

    2012-03-01

    We motivate the study of an 'N-scheme' atomic system for the case of a bi-directional probe field. We derive the equations of motion. The equations were expanded in order of the counter-propagating field strength over the co-propagating field strength. We solve the equations numerically in steady state in a perturbative manner. The zeroth order solutions describe the dispersion and absorption of the co-propagating field, while the first order solutions describe the dispersion and absorption of the counter-propagating field. We investigate the solutions in two temperature regimes for a variety of field strengths. Regimes of similar dispersion for the co- and counter-propagating fields were found, as well as regimes of opposite behavior. In most cases, absorption of the fields is still a problem.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wyer, J A; Latimer, C J; Shah, M B; Currell, F J [Centre for Plasma Physics, IRCEP, Queen' s University Belfast, BT7 1NN (United Kingdom); Butterworth, K T; Hirst, D G [Experimental Therapeutics Research Group, School of Pharmacy, Queen' s University Belfast, BT9 7BL (United Kingdom); Montenegro, E C [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Cx. Postal 68528, Rio de Janeiro, RJ 21941-972 (Brazil)], E-mail: jeanwyer@phys.au.dk

    2009-08-07

    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.

  19. 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...

  20. 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. Copyright © 2015 Acta Materialia Inc. Published by Elsevier

  1. 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.

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

    Science.gov (United States)

    Irimia, Daniel; Dobrikov, Dimitar; Kortekaas, Rob; Voet, Han; van den Ende, Daan A; Groen, Wilhelm A; Janssen, Maurice H M

    2009-11-01

    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 micros 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 microm nozzle releases about 10(16) particles/pulse and the beam brightness was estimated to be 4x10(22) 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 (Delta v/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

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

    Science.gov (United States)

    Irimia, Daniel; Dobrikov, Dimitar; Kortekaas, Rob; Voet, Han; van den Ende, Daan A.; Groen, Wilhelm A.; Janssen, Maurice H. M.

    2009-11-01

    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 4×1022 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 5×10-6 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

  4. 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.

  5. APPLICATIONS OF LASERS AND OTHER TOPICS IN LASER PHYSICS AND TECHNOLOGY: Investigation of the properties of resonance holograms in a beam of sodium atoms

    Science.gov (United States)

    Grigoriev, Igor'S.; Likhanskiĭ, V. V.; Semerok, A. F.; Firsov, Valerii A.; Chankin, A. V.

    1987-10-01

    Experimental and theoretical (using a two-level approximation) investigations were made of the properties of resonance holograms (excited-state gratings) created by monochromatic linearly polarized radiation from a cw dye laser in a beam of sodium atoms as a result of the 32P3/2- 32S1/2(F=2) transition. A good qualitative agreement was observed between the theory and experimental results. It was established that the maximum diffraction efficiency was attained when the intensity of the radiation used to form the hologram was of the order of the intensity needed to saturate the transition and the optical thickness of the beam was ~1.1. The sensitivity of the medium was ~1 nJ/cm2 for 1% diffraction efficiency.

  6. 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.

  7. Growth of Atomic Hexagonal Boron Nitride Layers and Graphene/Hexagonal Boron Nitride Heterostructures by Molecular Beam Epitaxy

    Science.gov (United States)

    Xu, Zhongguang

    Graphene, as a famous Van der Waals material, has attracted intensive attention from research group and industry all over the world after 2004, while hexagonal boron nitride (h-BN), as an excellent two-dimensional (2D) dielectric layer, has been studied intensively mainly for its compatibility with graphene and other 2D materials. To realize the technological potential of 2D system, it is essential to synthesize large-area, high-quality 2D thin films through a scalable and controllable method in order to investigate novel phenomenon in fundamental physics and promising device applications. In this thesis, the growth of graphene, h-BN and their vertical and lateral heterostructures by molecular beam epitaxy (MBE) is mainly discussed. In addition, the growth mechanism, fundamental physics and possible applications are also studied. In-situ epitaxial growth of graphene/h-BN heterostructures on cobalt (Co) film substrate was achieved by using plasma-assisted MBE in Chapter 2. We demonstrated a solution for direct fabricating graphene/h-BN vertical stacking structures. Various characterizations, such as Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM), were carried out to confirm and evaluate the heterostructures. Wafer-scale heterostructures consisting of single-layer/bilayer graphene and multilayer h-BN were achieved. The mismatch angle between graphene and h-BN is below 1°. Chapter 3 studied the growth of graphene/h-BN heterostructures on Co foil substrate by plasma-assisted MBE. It is found that the coverage of h-BN layers on the epitaxial thin graphite layer is growth-time dependent. Large-area, uniform-quality h-BN film was successfully deposited on thin graphite layer. Based on the as-grown h-BN (5-6 nm)/G (26-27 nm) heterostructure, without using any transferring process, we fabricated capacitor devices with Co(foil)/G/h-BN/Co(contact) configuration to evaluate the

  8. Beam Dynamics

    CERN Document Server

    Wilson, E

    2013-01-01

    This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Chapter '2 Beam Dynamics' with the content: 2 Beam Dynamics 2.1 Linear Transverse Beam Dynamics 2.2 Coupling 2.3 Liouville's Theorem 2.4 Momentum Dependent Transverse Motion 2.5 Longitudinal Motion

  9. 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.

  10. 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.

  11. Electron-atom collision studies using optically state selected beams. Progress report, May 15, 1987--May 14, 1988

    Energy Technology Data Exchange (ETDEWEB)

    Celotta, R.J.; Kelley, M.H.

    1988-11-15

    This report discusses progress made during the current contract period on the authors research program to study collisions between spin-polarized electrons and optically prepared atoms. The objective of this work is to stimulate a deeper theoretical understanding of the electron-atom interaction by providing more complete experimental measurements on colliding systems. By preparing the internal states of the collision partners before scattering, they are able to extract substantially more information about the scattering process than is available from more conventional measurements of differential cross sections. The authors are principally interested in observing the role played by spin in low energy electron-atom collisions. The additional information provided by these spin-dependent measurements can greatly enhance understanding of both exchange and the spin-orbit interaction in the scattering process. They have made substantial progress in the past three years in their measurements both of elastic and superelastic scattering of spin-polarized electrons from optically pumped sodium.

  12. Order within disorder: The atomic structure of ion-beam sputtered amorphous tantala (a-Ta_2O_5)

    OpenAIRE

    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.; Roger K. Route; Rowan, Sheila; Stebbins, Jonathan F.

    2015-01-01

    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...

  13. 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...

  14. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kalashnyk, Nataliya; Khemliche, Hocine; Roncin, Philippe, E-mail: philippe.roncin@u-psud.fr

    2016-02-28

    Highlights: • A new technique to monitor on-line, the growth and organization of organic molecules. • Atom beam triangulation points directions where the molecules align to each other. • The contrast is given by the variation of the width of the scattering pattern. • It is non-destructive and detects early stages of the organization. • The system investigated is self-assembly of perylene on Ag(1 1 0) at room temperature. - Abstract: 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.

  16. Structure formation in atom lithography using geometric collimation

    NARCIS (Netherlands)

    Meijer, T.; Beardmore, J.P.; Fabrie, C.G.C.H.M.; van Lieshout, J.P.; Notermans, R.P.M.J.W.; Sang, R.T.; Vredenbregt, E.J.D.; Van Leeuwen, K.A.H.

    2011-01-01

    Atom lithography uses standing wave light fields as arrays of lenses to focus neutral atom beams into line patterns on a substrate. Laser cooled atom beams are commonly used, but an atom beam source with a small opening placed at a large distance from a substrate creates atom beams which are locally

  17. Ion beam generated plasmas described from the view of atomic physics. Atomphysikalische Beschreibung ionenstrahl-erzeugter Plasmen

    Energy Technology Data Exchange (ETDEWEB)

    Kaercher, B.

    1991-06-01

    The aim of this thesis is the description of ion-beam-driven plasmas by means of rate equations. Emphasis is put on the numerical and analytical study of the state and radiation emission of these non-equilibrium systems and on their stopping power for swift projectile ions. Important features of the quasi-stationary non-equilibrium states of ion-beam-generated plasmas are discussed by describing the degree of ionization as well as the distribution of ionization stages and the excited level populations of the plasma ions. The investigation of the energy balance of ion-beam-driven plasmas illustrates that the specific deposition power is only a weak function of the plasma temperature and density. On the contrary, the radiation emission shows significant structure, leading to the possibility of several equilibrium points which may be reached by the beam-plasma-system depending on its initial state. The time needed to build up an equilibrium temperature is long compared to both the time after which a temperature for the free electrons can be defined and the typical time scale of relaxation of the level populations. Furthermore this work presents an analytical discussion of the conversion of ion beam energy into radiation emission from the K-band of the plasma target for all elements. Finally, the energy loss of fast projectile ions in partially ionized, dense plasmas is investigated with emphasis on the changes of the average ionization potentials compared to cold matter. It is shown that the influence of excited state populations in the plasma ions may enhance the energy loss up to 13% in the case of a hydrogen plasma. As far as weakly ionized high-Z matter is concerned, a known reduction of the energy loss of about 10% is confirmed and systematically studied for the elements of the periodic table. (orig./AH).

  18. Scattering of thermal He beams by crossed atomic and molecular beams. III. Anisotropic intermolecular potentials for He + N/sub 2/, O/sub 2/, CO, and NO

    Energy Technology Data Exchange (ETDEWEB)

    Keil, M.; Slankas, J.T.; Kuppermann, A.

    1979-01-01

    Differential scattering cross sections are measured for He + N/sub 2/, O/sub 2/, CO, and NO, using the crossed molecular beams technique. These data, which are sensitive to the van der Waals attractive minima and adjacent regions of the intermolecular potentials, are analyzed in terms of both central-field and anisotropic models. Little evidence is found for quenching of the observed diffraction oscillations, and anisotropic contributions are determined to be small:The spherical averages of these anisotropic potentials are indistinguishable, within experimental error, from the potentials obtained by a central-field analysis. This study thus provides a quantitative, empirical validation of the central-field assumption for molecular scattering in weakly anisotropic systems.

  19. 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 ...

  20. Orientation dependence in the four-atom reaction of OH + HBr using the single-state oriented OH radical beam.

    Science.gov (United States)

    Tsai, Po-Yu; Che, Dock-Chil; Nakamura, Masaaki; Lin, King-Chuen; Kasai, Toshio

    2010-03-20

    The orientation dependence for the Br atom formation in the reaction of the oriented OH radicals with HBr molecules at 0.26 eV collision energy has been observed for the first time using the hexapole electric field, and we found that the reaction cross-section for O-end attack is more favorable than that for H-end attack by a factor of 3.4 +/- 2.3.

  1. 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.

  2. Ion-beam modification of 2-D materials - single implant atom analysis via annular dark-field electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bangert, U., E-mail: Ursel.Bangert@ul.ie [Department of Physics, School of Sciences & Bernal Institute, University of Limerick, Limerick (Ireland); Stewart, A.; O’Connell, E.; Courtney, E. [Department of Physics, School of Sciences & Bernal Institute, University of Limerick, Limerick (Ireland); Ramasse, Q.; Kepaptsoglou, D. [SuperSTEM Laboratory, STFC Daresbury Campus, Daresbury WA4 4AD (United Kingdom); Hofsäss, H.; Amani, J. [II. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-PLatz 1, 37077 Göttingen (Germany); Tu, J.-S.; Kardynal, B. [Peter Grünberg Institut 9, Forschungszentrum Jülich, 52425 Jülich (Germany)

    2017-05-15

    Functionalisation of two-dimensional (2-D) materials via low energy ion implantation could open possibilities for fabrication of devices based on such materials. Nanoscale patterning and/or electronically doping can thus be achieved, compatible with large scale integrated semiconductor technologies. Using atomic resolution High Angle Annular Dark Field (HAADF) scanning transmission electron microscopy supported by image simulation, we show that sites and chemical nature of individual implants/ dopants in graphene, as well as impurities in hBN, can uniquely and directly be identified on grounds of their position and their image intensity in accordance with predictions from Z-contrast theories. Dopants in graphene (e.g., N) are predominantly substitutional. In other 2-Ds, e.g. dichalcogenides, the situation is more complicated since implants can be embedded in different layers and substitute for different elements. Possible configurations of Se-implants in MoS{sub 2} are discussed and image contrast calculations performed. Implants substituting for S in the top or bottom layer can undoubtedly be identified. We show, for the first time, using HAADF contrast measurement that successful Se-integration into MoS{sub 2} can be achieved via ion implantation, and we demonstrate the possibility of HAADF image contrast measurements for identifying impurities and dopants introduced into in 2-Ds. - Highlights: • Ion implantation of 2-dimensional materials. • Targeted and controlled functionalisation of graphene and 2-D dichalcocenides. • Atomic resolution High Angle Dark Field scanning transmission electron microscopy. • Determination of atomic site and elemental nature of dopants in 2-D materials. • Quantitative information from Z-contrast images.

  3. 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.

  4. 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.

  5. Fabrication of sharp tungsten-coated tip for atomic force microscopy by ion-beam sputter deposition.

    Science.gov (United States)

    Kinoshita, Yukinori; Naitoh, Yoshitaka; Li, Yan Jun; Sugawara, Yasuhiro

    2011-11-01

    Tungsten (W) is significantly suitable as a tip material for atomic force microscopy (AFM) because its high mechanical stiffness enables the stable detection of tip-sample interaction forces. We have developed W sputter-coating equipment to compensate the drawbacks of conventional Si cantilever tips used in AFM measurements. By employing an ion gun commonly used for sputter cleaning of a cantilever tip, the equipment is capable of depositing conductive W films in the preparation chamber of a general ultrahigh vacuum (UHV)-AFM system without the need for an additional chamber or transfer system. This enables W coating of a cantilever tip immediately after sputter cleaning of the tip apex and just before the use in AFM observations. The W film consists of grain structures, which prevent tip dulling and provide sharpness (coated Si tip can clearly resolve the atomic structures of a Ge(001) surface without any artifacts, indicating that, as a force sensor, the fabricated W-coated Si tip is superior to a bare Si tip. © 2011 American Institute of Physics

  6. Contactless friction and the {sup 3}He-{sup 4}He dimer. Studies with the atomic-beam spin-echo spectrometer; Kontaktlose Reibung und das {sup 3}He-{sup 4}He-Dimer. Untersuchungen mit dem Atomstrahlspinechospektrometer

    Energy Technology Data Exchange (ETDEWEB)

    Janke, Matthias

    2016-04-20

    In this thesis the time of flight resolved atomic beam spin echo method (SEToF) is applied to a {sup 3}He-beam for the first time and studied systematically. This method is shown to be superior to the usual atomic beam spin echo technique. With SEToF it is possible to almost completely remove unpolarized background and to reach a beam polarisation close to 100%. The SEToF technique is shown to be crucial for the first experimental proof of the existence of the {sup 3}He-{sup 4}He dimer. This dimer is the weakest bound van-der-Waals-molecule known to date. Furthermore, a drag force between an atom and a dielectric surface is detected originating from the fluctuating dipole moment of the atom. Not only the measured friction coefficients match their theoretical predictions perfectly, but our data also shows the correct temperature dependence. A great many technological renewals and improvements were installed in the apparatus during this thesis work. They have become necessary or sensible due to the relocation of the physics institute. A few of them are documented and motivated in this thesis.

  7. 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.

  8. Study of gamma-ray emission by proton beam interaction with injected Boron atoms for future medical imaging applications

    Science.gov (United States)

    Petringa, G.; Cirrone, G. A. P.; Caliri, C.; Cuttone, G.; Giuffrida, L.; Larosa, G.; Manna, R.; Manti, L.; Marchese, V.; Marchetta, C.; Margarone, D.; Milluzzo, G.; Picciotto, A.; Romano, F.; Romano, F. P.; Russo, A. D.; Russo, G.; Santonocito, D.; Scuderi, V.

    2017-03-01

    In this work an experimental and theoretical study of gamma-prompt emission has been carried out with the main aim being to understand to what extent this approach can be used during a treatment based on proton-boron fusion therapy. An experimental campaign, carried out with a high purity Germanium detector, has been performed to evaluate the gamma emission from two pure 11B and 10B targets. Furthermore, a set of analytical simulations, using the Talys nuclear reaction code has been performed and the calculated spectra compared with the experimental results. These comparisons allowed us to successfully validate Talys which was then used to estimate the gamma emission when a realistic Boron concentration was considered. Both simulations and experimental results suggest that the gamma emission is low at certain proton energies, thus in order to improve the imaging capabilities, while still maintaining the Boron therapeutic role, we propose the addition of natural Copper bound by a dipyrromethene, BodiPy, to boron atoms. Analytical simulations with Talys suggest that the characteristic spectrum of the copper prompt gamma-rays has several peaks in the energetic regions where the background is negligible.

  9. Area-selective atomic layer deposition of Ru on electron-beam-written Pt(C) patterns versus SiO2 substratum

    Science.gov (United States)

    Junige, Marcel; Löffler, Markus; Geidel, Marion; Albert, Matthias; Bartha, Johann W.; Zschech, Ehrenfried; Rellinghaus, Bernd; van Dorp, Willem F.

    2017-09-01

    Area selectivity is an emerging sub-topic in the field of atomic layer deposition (ALD), which employs opposite nucleation phenomena to distinct heterogeneous starting materials on a surface. In this paper, we intend to grow Ru exclusively on locally pre-defined Pt patterns, while keeping a SiO2 substratum free from any deposition. In a first step, we study in detail the Ru ALD nucleation on SiO2 and clarify the impact of the set-point temperature. An initial incubation period with actually no growth was revealed before a formation of minor, isolated RuO x islands; clearly no continuous Ru layer formed on SiO2. A lower temperature was beneficial in facilitating a longer incubation and consequently a wider window for (inherent) selectivity. In a second step, we write C-rich Pt micro-patterns on SiO2 by focused electron-beam-induced deposition (FEBID), varying the number of FEBID scans at two electron beam acceleration voltages. Subsequently, the localized Pt(C) deposits are pre-cleaned in O2 and overgrown by Ru ALD. Already sub-nanometer-thin Pt(C) patterns, which were supposedly purified into some form of Pt(O x ), acted as very effective activation for the locally restricted, thus area-selective ALD growth of a pure, continuous Ru covering, whereas the SiO2 substratum sufficiently inhibited towards no growth. FEBID at lower electron energy reduced unwanted stray deposition and achieved well-resolved pattern features. We access the nucleation phenomena by utilizing a hybrid metrology approach, which uniquely combines in-situ real-time spectroscopic ellipsometry, in-vacuo x-ray photoelectron spectroscopy, ex-situ high-resolution scanning electron microscopy, and mapping energy-dispersive x-ray spectroscopy.

  10. X-ray photoelectron spectroscopy and conducting atomic force microscopy investigations on dual ion beam sputtered MgO ultrathin films

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Braj Bhusan [Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India); Agrawal, Vikash; Joshi, Amish G. [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110 012 (India); Chaudhary, Sujeet, E-mail: sujeetc@physics.iitd.ac.in [Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India)

    2012-09-01

    Ultrathin films of MgO ({approx} 6 nm) were deposited on Si(100) using dual ion beam sputtering in different partial pressures of oxygen. These thin films were characterized by X-ray photoelectron spectroscopy (XPS) for chemical state analysis and conducting atomic force microscopy for topography and local conductivity map. No trace of metal Mg was evidenced in these MgO films. The XPS analysis clearly brought out the formation of oxygen interstitials and Mg(OH){sub 2} primarily due to the presence of residual water vapors in the chamber. An optimum value of oxygen partial pressure of {approx} 4.4 Multiplication-Sign 10{sup -2} Pa is identified with regard to homogeneity of film and stoichiometry across the film thickness (O:Mg::0.93-0.97). The local conductivity mapping investigations also established the film homogeneity in respect of electrical resistivity. Non-linear local current-voltage curves revealed typical tunneling characteristics with barrier width of {approx} 5.6 nm and barrier height of {approx} 0.92 eV. - Highlights: Black-Right-Pointing-Pointer Ultra-thin films ({approx} 6 nm) of MgO were deposited at different oxygen partial pressures. Black-Right-Pointing-Pointer Chemical state of MgO thin films is investigated by X-ray photoelectron spectroscopy. Black-Right-Pointing-Pointer Local conductivity map was investigated using conducting atomic force microscopy. Black-Right-Pointing-Pointer Current-voltage characteristics at local points showed tunneling like behavior.

  11. Scattering of thermal He beams by crossed atomic and molecular beams. IV. Spherically symmetric intermolecular potentials for He+CH/sub 4/, NH/sub 3/, H/sub 2/O, SF/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Slankas, J.T.; Keil, M.; Kuppermann, A.

    1979-02-01

    Differential scattering cross sections are measured for He+CH/sub 4/, NH/sub 3/, H/sub 2/O, and SF/sub 6/, using the crossed molecular beams technique. These data, which are sensitive to the van der Waals attractive minima and adjacent regions of the intermolecular potential, are interpreted in terms of central-field models. No evidence is found for quenching of the observed diffraction oscillations. The interactions of the isoelectronic hydrides CH/sub 4/, NH/sub 3/, H/sub 2/O with He are found to have decreasing van der Waals radii in this sequence, and their attractive wells all have similar depths. However, the He+SF/sub 6/ attractive well is found to be anomalously deep, and provides a counter example to the supposition that only the polarizability of the least polarizable of the interacting partners (atoms or molecules) correlates with the van der Waals well depth. Simple combination rules for predicting unlike-pair potential parameters from the corresponding like-pair ones are tested and found inadequate.

  12. Atomic Clocks Research - An Overview.

    Science.gov (United States)

    1987-08-15

    magnet. Since atomic deflection in an inhomogeneous magnetic field is inversely proportional to the square of the atomic speed, the atomic velocity...purifier and controlled leak; an atomic source (i.e., the dissociator under 39 study); a dipole electromagnetic with pole pieces shaped to produce an...34Relaxation Magnetique d’Atomes de Rubidium sur des Parois Paraffines," J. Phys. (Paris) 24, 379 (1963). 21. S. Wexler, "Deposition of Atomic Beams

  13. 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.

  14. Beam-beam instability

    Energy Technology Data Exchange (ETDEWEB)

    Chao, A.W.

    1983-08-01

    The subject of beam-beam instability has been studied since the invention of the colliding beam storage rings. Today, with several colliding beam storage rings in operation, it is not yet fully understood and remains an outstanding problem for the storage ring designers. No doubt that good progress has been made over the years, but what we have at present is still rather primitive. It is perhaps possible to divide the beam-beam subject into two areas: one on luminosity optimization and another on the dynamics of the beam-beam interaction. The former area concerns mostly the design and operational features of a colliding beam storage ring, while the later concentrates on the experimental and theoretical aspects of the beam-beam interaction. Although both areas are of interest, our emphasis is on the second area only. In particular, we are most interested in the various possible mechanisms that cause the beam-beam instability.

  15. beam-beam interaction

    CERN Multimedia

    2017-01-01

    The Beam 1 (represented in blue) and the Beam 2 (represented in red) are colliding with an angle at the Interaction Point (IP). The angle is needed to avoid unwanted multiple collisions along the interaction region. Despite of the separation introduced by the angle, the two beams interact via their electromagnetic field, the so called "beam-beam" interaction.

  16. Absorption imaging of ultracold atoms on atom chips

    DEFF Research Database (Denmark)

    Smith, David A.; Aigner, Simon; Hofferberth, Sebastian

    2011-01-01

    Imaging ultracold atomic gases close to surfaces is an important tool for the detailed analysis of experiments carried out using atom chips. We describe the critical factors that need be considered, especially when the imaging beam is purposely reflected from the surface. In particular we present...... methods to measure the atom-surface distance, which is a prerequisite for magnetic field imaging and studies of atom surface-interactions....

  17. Modern atomic physics

    CERN Document Server

    Natarajan, Vasant

    2015-01-01

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

  18. The identification of autoionizing states of atomic chromium for the resonance ionization laser ion source of the ISOLDE radioactive ion beam facility

    CERN Document Server

    Goodacre, T Day; Fedorovc, D; Fedosseev, V N; Marsh, B A; Molkanov, P; Rossel, R E; Rothe, S; Seiffert, C

    2015-01-01

    The resonance ionization laser ion source (RILIS) is the principal ion source of the ISOLDE radioactive beam facility based at CERN. Using the method of in-source resonance ionization spectroscopy, an optimal three-step, three-resonance photo-ionization scheme has been developed for chromium. The scheme uses an ionizing transition to one of the 14 newly observed autoionizing states. This work increases the range of ISOLDE-RILIS ionized beams to 32 chemical elements. Details of the spectroscopic studies are described and the new ionization scheme is summarized. A link to the complete version of this document will be added here following publication:

  19. The effect of laser beam size in a zig-zag collimator on transverse ...

    Indian Academy of Sciences (India)

    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 ...

  20. 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.

  1. Design of a High-Perveance Electron Gun for Electron Cooling in the Low Energy Ion Ring (LEIR) at CERN and Non-Interceptive Proton Beam Profile Monitors using Ion or Atomic Probe Beams

    CERN Document Server

    Dimopoulou, Christina

    2002-01-01

    For an efficient electron cooling of the low-energy Pb54+ ions in LEIR a high-perveance (at least 3.6microperv) electron gun had to be designed. The theoretical study of electron guns has shown that the required perveance can be achieved by using a convex cathode. The gun should be immersed in a strong magnetic field (B=2-6kG) in order to obtain a parallel beam with very low transverse energy (typically 0.1 eV). This idea was confirmed by experimental tests at Fermilab. An adiabatic magnetic expansion is foreseen after the gun in order to reduce the magnetic field to accpetable values (0.6-1 kG) in the cooling section. The internal geometry of a convex cathode gun for the LEIR electron cooler together with the parameters of the magnetic expansion are proposed. The scheme fulfils the requirements. In addition, the author has made an important contribution in the field of beam instrumentation for the LHC and other accelerators at CERN. A profile monitor has been developed that uses a Xe ion probe beam that inte...

  2. Atomic collisions involving pulsed positrons

    DEFF Research Database (Denmark)

    Merrison, J. P.; Bluhme, H.; Field, D.

    2000-01-01

    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....

  3. 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.

  4. Atomic form factor for twisted vortex photons interacting with atoms

    Science.gov (United States)

    Guthrey, Pierson; Kaplan, Lev; McGuire, J. H.

    2014-04-01

    The relatively new atomic form factor for twisted (vortex) beams, which carry orbital angular momentum (OAM), is considered and compared to the conventional atomic form factor for plane-wave beams that carry only spin angular momentum. Since the vortex symmetry of a twisted photon is more complex that that of a plane wave, evaluation of the atomic form factor is also more complex for twisted photons. On the other hand, the twisted photon has additional parameters, including the OAM quantum number, ℓ, the nodal radial number, p, and the Rayleigh range, zR, which determine the cone angle of the vortex. This Rayleigh range may be used as a variable parameter to control the interaction of twisted photons with matter. Here we address (i) normalization of the vortex atomic form factor, (ii) displacement of target atoms away from the center of the beam vortex, and (iii) formulation of transition probabilities for a variety of photon-atom processes. We attend to features related to experiments that can test the range of validity and accuracy of calculations of these variations of the atomic form factor. Using the absolute square of the form factor for vortex beams, we introduce a vortex factor that can be directly measured.

  5. A new method to induce transitions in muonic atoms using a high-power tunable dye laser coupled to a stopping muon beam

    CERN Document Server

    Bertin, A; Duclos, J; Gastaldi, Ugo; Gorini, G; Neri, G; Picard, J; Pitzurra, O; Placci, A; Polacco, E; Stefanini, G; Torelli, G; Vitale, A; Zavattini, E

    1974-01-01

    An apparatus is described in which a ruby-pumped dye laser is used to induce transitions from the 2S to the 2P levels of the muonic ion ( mu He)/sup +/. The dye laser supplies infra-red radiation pulses in the wavelengths (8040-8180) AA, at typical repetition rates of 1 pulse every 4 s, with an energy release per pulse of 300 mJ for 1.2 J pumping energy. A special synchronization procedure is followed to trigger the laser in close coupling with the incoming muon beam which is stopped in a helium target at pressures between 40 and 50 atm. The other performances of the device are fully discussed with reference both to the laser facility and to the special high-pressure helium target. (23 refs).

  6. A compact molecular beam machine.

    Science.gov (United States)

    Jansen, Paul; Chandler, David W; Strecker, Kevin E

    2009-08-01

    We have developed a compact, low cost, modular, crossed molecular beam machine. The new apparatus utilizes several technological advancements in molecular beams valves, ion detection, and vacuum pumping to reduce the size, cost, and complexity of a molecular beam apparatus. We apply these simplifications to construct a linear molecular beam machine as well as a crossed-atomic and molecular beam machine. The new apparatus measures almost 50 cm in length, with a total laboratory footprint less than 0.25 m(2) for the crossed-atomic and molecular beam machine. We demonstrate the performance of the apparatus by measuring the rotational temperature of nitric oxide from three common molecular beam valves and by observing collisional energy transfer in nitric oxide from a collision with argon.

  7. Chameleon Induced Atomic Afterglow

    CERN Document Server

    Brax, Philippe

    2010-01-01

    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.

  8. Laser stabilisation for velocity-selective atomic absorption

    NARCIS (Netherlands)

    Meijer, H.A.J.; Meulen, H.P. van der; Ditewig, F.; Wisman, C.J.; Morgenstern, R.

    1987-01-01

    A relatively simple method is described for stabilising a dye laser at a frequency ν = ν0 + νc in the vicinity of an atomic resonance frequency ν0. The Doppler effect is exploited by looking for atomic fluorescence when a laser beam is crossed with an atomic beam at certain angles αi. Absolute

  9. 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...

  10. 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...

  11. Navigation with Atom Interferometers

    Science.gov (United States)

    2017-03-20

    stability of the design and will be measured at a future time. Angle random walk can be calculated from first principles from the shot-noise limited...interferometer cannot distinguish between the two sources of phase shifts. We describe a design for a dual atom interferometer to simultaneously...stability. This paper is organized as follows: we first describe the basic building blocks of the interferometer: beam splitters and mirrors. We then

  12. Atomic interferometry; Interferometrie atomique

    Energy Technology Data Exchange (ETDEWEB)

    Baudon, J.; Robert, J. [Paris-13 Univ., 93 - Saint-Denis (France)

    2004-07-01

    Since the theoretical works of L. De Broglie (1924) and the famous experiment of Davisson and Germer (1927), we know that a wave is linked with any particle of mass m by the relation {lambda} = h/(mv), where {lambda} is the wavelength, v the particle velocity and h is the Planck constant. The basic principle of the interferometry of any material particle, atom, molecule or aggregate is simple: using a simple incident wave, several mutually consistent waves (with well-defined relative phases) are generated and controllable phase-shifts are introduced between them in order to generate a wave which is the sum of the previous waves. An interference figure is obtained which consists in a succession of dark and bright fringes. The atomic interferometry is based on the same principle but involves different techniques, different wave equations, but also different beams, sources and correlations which are described in this book. Because of the small possible wavelengths and the wide range of possible atomic interactions, atomic interferometers can be used in many domains from the sub-micron lithography to the construction of sensors like: inertial sensors, gravity-meters, accelerometers, gyro-meters etc. The first chapter is a preliminary study of the space and time diffraction of atoms. The next chapters is devoted to the description of slit, light separation and polarization interferometers, and the last chapter treats of the properties of Bose-Einstein condensates which are interesting in atomic interferometry. (J.S.)

  13. 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.

  14. 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

  15. 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 ...

  16. Ultracold atoms on atom chips

    DEFF Research Database (Denmark)

    Krüger, Peter; Hofferberth, S.; Haller, E.

    2005-01-01

    Miniaturized potentials near the surface of atom chips can be used as flexible and versatile tools for the manipulation of ultracold atoms on a microscale. The full scope of possibilities is only accessible if atom-surface distances can be reduced to microns. We discuss experiments in this regime...

  17. 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)

  18. Accelerator Technology: Beam Instrumentation and Diagnostics

    CERN Document Server

    Jones, R; Schmickler, H

    2013-01-01

    This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the the Section '8.6 Beam Instrumentation and Diagnostics' of the Chapter '8 Accelerator Technology' with the content: 8.6 Beam Instrumentation and Diagnostics 8.6.1 Beam Position Measurement 8.6.2 Beam Current and Intensity Measurement 8.6.3 Diagnostics of Transverse Beam Motion 8.6.4 Beam Profile Measurements 8.6.5 Beam Loss Monitoring 8.6.6 Short Bunch Length Diagnostics

  19. 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...... mechanism allows for the production of a constant flux of 4.5×106 atoms per second and due to transverse guiding we obtain an upper limit for the mean beam width of 4.6 μm. The transverse velocity spread is only 0.2 mm/s and thus an upper limit for the beam quality parameter is M 2=2.5. We demonstrate...... the potential of the long interrogation times available with this atom laser beam by measuring the trap frequency in a single measurement. The small beam width together with the long evolution and interrogation time makes this atom laser beam a promising tool for continuous interferometric measurements....

  20. High-brightness ultra-cold metastable neon-beam

    CERN Document Server

    Shimizu, Fujio

    2015-01-01

    This paper presents detailed characteristics of an ultra-cold bright metastable neon atomic beam which we have been using for atom-interferometric applications. The basis of the device is an atomic beam released from a magneto-optical trap (MOT) which is operated with a high intensity trapping laser, high magnetic quadrupole field, and large laser detuining. Mainly due to the complex structure of three dimensional magnetic field and laser beams, a bright small spot of atoms is formed near the center of the quadrupole magnetic field under an appropriate operating condition. We obtained the minimum trap diameter of 50 micron meter, the atomic density nearly 10^{13}cm^{-3}, and the atomic temperature slightly less than the Doppler limited temperature of 200 micro-K. By releasing trapped atoms we obtained an bright cold atomic beam which is not far from the collision limited atomic density.

  1. 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

  2. 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.

  3. Atomic force microscopical and surface plasmon resonance spectroscopical investigation of sub-micrometer metal gratings generated by UV laser-based two-beam interference in Au-Ag bimetallic layers

    Energy Technology Data Exchange (ETDEWEB)

    Csete, M. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: mcsete@physx.u-szeged.hu; Kohazi-Kis, A. [Faculty of Mechanical Engineering and Automation, Kecskemet College, H-6000 Kecskemet, Izsaki str. 10 (Hungary); Vass, Cs. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Sipos, A. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Szekeres, G. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Deli, M. [Laboratory of Molecular Neurobiology, Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Temesvari Krt. 62, H-6726 Szeged (Hungary); Osvay, K. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Bor, Zs. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary)

    2007-07-31

    Metal films containing silver and gold layers having different thicknesses were evaporated on glass substrates. Two-beam interference technique was applied to irradiate the surfaces by the fourth harmonic of a pulsed mode Nd:YAG laser. The atomic force microscopical study showed that surface relief grating having a period of 900 nm corresponding to the interference pattern was developed on the metallic films. The modulation amplitude of the laser-induced gratings was increasable by enhancing the number of laser pulses at constant fluence, and a groove depth commensurable with the film thicknesses was generated at the average fluence of 39.5 mJ/cm{sup 2} on bimetallic layers. The surface structure was more regular, and the modulation amplitude was larger in case of bimetallic films containing thicker gold layers. The threshold fluences of the phase transitions were determined by numerical temperature model calculations for different metal layer compositions, and a good agreement was found between the calculated and experimentally observed threshold values. The division of the metal stripes into droplets and the development of holes were explained by the melting of the entire metal layers and by the vaporization of silver at higher fluences. The angle-dependent surface plasmon resonance spectroscopy realized in Kretschmann arrangement proved that the laser-induced grating formation was accompanied by the change in the optical thickness and by the modification of the structure of the bimetallic films. Broad side wings appeared on the resonance curves caused by grating-coupling in case of appropriate rotation angle and sufficiently large modulation depth of the grating's grooves, according to our calculations. The coupling on deep gratings developed on bimetallic films containing the thinnest gold layer and on monometallic silver films resulted in separated secondary resonance minimum development. The periodic adherence of native streptavidin on the metallic

  4. Atomic physics

    CERN Document Server

    Born, Max

    1969-01-01

    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.

  5. Early Atomism

    Indian Academy of Sciences (India)

    http://www.ias.ac.in/article/fulltext/reso/015/10/0905-0925. Keywords. Atomic theory; Avogadro's hypothesis; atomic weights; periodic table; valence; molecular weights; molecular formula; isomerism. Author Affiliations. S Ramasesha1. Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, ...

  6. 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

  7. Self-excitation of Rydberg atoms at a metal surface

    DEFF Research Database (Denmark)

    Bordo, Vladimir

    2017-01-01

    The novel effect of self-excitation of an atomic beam propagating above a metal surface is predicted and a theory is developed. Its underlying mechanism is positive feedback provided by the reflective surface for the atomic polarization. Under certain conditions the atomic beam flying in the near...... field of the metal surface acts as an active device that supports sustained atomic dipole oscillations, which generate, in their turn, an electromagnetic field. This phenomenon does not exploit stimulated emission and therefore does not require population inversion in atoms. An experiment with Rydberg...... atoms in which this effect should be most pronounced is proposed and the necessary estimates are given....

  8. Efficient transfer of francium atoms

    Science.gov (United States)

    Aubin, Seth; Behr, John; Gorelov, Alexander; Pearson, Matt; Tandecki, Michael; Collister, Robert; Gwinner, Gerald; Shiells, Kyle; Gomez, Eduardo; Orozco, Luis; Zhang, Jiehang; Zhao, Yanting; FrPNC Collaboration

    2016-05-01

    We report on the progress of the FrPNC collaboration towards Parity Non Conservation Measurements (PNC) using francium atoms at the TRIUMF accelerator. We demonstrate efficient transfer (higher than 40%) to the science vacuum chamber where the PNC measurements will be performed. The transfer uses a downward resonant push beam from the high-efficiency capture magneto optical trap (MOT) towards the science chamber where the atoms are recaptured in a second MOT. The transfer is very robust with respect to variations in the parameters (laser power, detuning, alignment, etc.). We accumulate a growing number of atoms at each transfer pulse (limited by the lifetime of the MOT) since the push beam does not eliminate the atoms already trapped in the science MOT. The number of atoms in the science MOT is on track to meet the requirements for competitive PNC measurements when high francium rates (previously demonstrated) are delivered to our apparatus. The catcher/neutralizer for the ion beam has been tested reliably to 100,000 heating/motion cycles. We present initial tests on the direct microwave excitation of the ground hyperfine transition at 45 GHz. Support from NSERC and NRC from Canada, NSF and Fulbright from USA, and CONACYT from Mexico.

  9. Optical lattice on an atom chip

    DEFF Research Database (Denmark)

    Gallego, D.; Hofferberth, S.; Schumm, Thorsten

    2009-01-01

    Optical dipole traps and atom chips are two very powerful tools for the quantum manipulation of neutral atoms. We demonstrate that both methods can be combined by creating an optical lattice potential on an atom chip. A red-detuned laser beam is retroreflected using the atom chip surface as a high......-quality mirror, generating a vertical array of purely optical oblate traps. We transfer thermal atoms from the chip into the lattice and observe cooling into the two-dimensional regime. Using a chip-generated Bose-Einstein condensate, we demonstrate coherent Bloch oscillations in the lattice....

  10. Ionisation of atomic hydrogen by positron impact

    Science.gov (United States)

    Spicher, Gottfried; Olsson, Bjorn; Raith, Wilhelm; Sinapius, Guenther; Sperber, Wolfgang

    1990-01-01

    With the crossed beam apparatus the relative impact-ionization cross section of atomic hydrogen by positron impact was measured. A layout of the scattering region is given. The first measurements on the ionization of atomic hydrogen by positron impact are also given.

  11. Relativistic atomic physics at the SSC

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1990-12-31

    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.

  12. Deflection of atoms by standing-wave radiation

    Science.gov (United States)

    Moskowitz, P. E.; Gould, P. L.; Pritchard, D. E.

    1985-11-01

    Momentum transfer from a standing-wave light field to an atomic beam has been observed. The atomic beam is split symmetrically into two peaks whose separation increases with field strength. The short interaction time ensures that this deflection is due to induced forces; these are described using a semiclassical dressed-atom treatment, which gives good agreement with the data. In addition to the splitting, diffraction of the atomic beam due to the exchange of even numbers of photons with the field has been observed.

  13. A polarized beams project at ISAC

    CERN Document Server

    Levy, C D P; Jayamanna, K; Kiefl, R; Kuo, T; Olivo, M; Wight, G W; Yuan, D; Zelenski, A N

    2002-01-01

    A polarizer beam line at the radioactive beams facility ISAC at TRIUMF is nearly complete. Initially for sup 8 Li sup + ions for beta-NMR studies in condensed matter, it can in principle supply three or more experiments simultaneously, and the technique used is practicable with all alkali-metal ion beams. An atomic beam, created with over 90% efficiency by passing the initial unpolarized 30 keV beam through a sodium vapor jet target, will be polarized by colinear optical pumping. A novel feature is that the atomic beam is reionized with demonstrated high efficiency in a helium gas target. The emittance growth through the helium cell has been measured for stable sup 7 Li sup + beam on a test stand and found to be small. We report these measurements as a function of helium flow rates. A preliminary polarized sup 8 Li sup + run is planned for May, 2000.

  14. Beam Diagnostics

    CERN Document Server

    Raich, U

    2013-01-01

    As soon as the first particles emerge from an ion source, the source characteristics need to be determined. The total beam intensity, the transverse particle distributions, the beam divergence and emittance as well as the longitudinal parameters of the beam must be measured. This chapter provides an overview of typical measurement methods and the instruments used, and shows the results obtained.

  15. 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.

  16. 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.

  17. 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

  18. 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)

  19. Spin-exchange frequency shift in a cesium atomic fountain

    NARCIS (Netherlands)

    Tiesinga, E.; Verhaar, B.J.; Stoof, H.T.C.; Bragt, D. van

    1992-01-01

    In connection with experiments aiming at the improvement of the cesium atomic beam clock by means of a fountain of laser-cooled cesium atoms, we present expressions for the line shift and line broadening due to collisions between cesium atoms. The coherent collision cross sections occurring in these

  20. nuclear and atomic methods applied in the determination of some ...

    African Journals Online (AJOL)

    free atoms in vapour state and a beam of electromagnetic radiation emitted from excited lead atoms is passed through the vaporized sample. Some of the radiation is absorbed by the lead atoms in the sample. Sample Collection and Preparation. Soil samples were collected from Bompai, Kofar Ruwa, Challawa and.

  1. Atomic Power

    African Journals Online (AJOL)

    Atomic Power. By Denis Taylor: Dr. Taylor was formerly Chief UNESCO Advisor at the University. College, Nairobi, Kenya and is now Professor of Electrical Engineering in the Uni- versity of ... method of producing radioactive isotopes, which are materials .... the sealing and the pressure balancing, all can be carried out ...

  2. 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.

  3. Atomic arias

    Science.gov (United States)

    Crease, Robert P.

    2009-01-01

    The American composer John Adams uses opera to dramatize controversial current events. His 1987 work Nixon in China was about the landmark meeting in 1972 between US President Richard Nixon and Chairman Mao Zedong of China; The Death of Klinghoffer (1991) was a musical re-enactment of an incident in 1985 when Palestinian terrorists kidnapped and murdered a wheelchair-bound Jewish tourist on a cruise ship. Adams's latest opera, Doctor Atomic, is also tied to a controversial event: the first atomic-bomb test in Alamogordo, New Mexico, on 16 June 1945. The opera premièred in San Francisco in 2005, had a highly publicized debut at the Metropolitan Opera in New York in 2008, and will have another debut on 25 February - with essentially the same cast - at the English National Opera in London.

  4. Atomic rivals

    Energy Technology Data Exchange (ETDEWEB)

    Goldschmidt, B.

    1990-01-01

    This book is a memoir of rivalries among the Allies over the bomb, by a participant and observer. Nuclear proliferation began in the uneasy wartime collaboration of the United States, England, Canada, and Free France to produce the atom bomb. Through the changes of history, a young French chemist had a role in almost every act of this international drama. This memoir is based on Goldschmidt's own recollections, interviews with other leading figures, and 3,000 pages of newly declassified documents in Allied archives. From his own start as Marie Curie's lab assistant, Goldschmidt's career was closely intertwined with Frances complicated rise to membership in the nuclear club. As a refugee from the Nazis, he became part of the wartime nuclear energy project in Canada and found himself the only French scientist to work (although briefly) on the American atom bomb project.

  5. Laser Cooling of Neutral Atoms.

    Science.gov (United States)

    1983-12-01

    wave monochromatic field interactint, with the atomic beam, the above assumption is justified. If the external field is a standing wave, and the atomo ...Substitute for the time derivatives using Schrodingers wave equation and perform some algebra to obtain, Integrate over the second term by parts twice...exponents into sin’s and cos’s. Calculating the indicated magnitude is tedious but straightforward. The real and imaginary parts of the equation are squared

  6. Laser Technology in Commercial Atomic Clocks

    Science.gov (United States)

    Lutwak, R.

    2006-05-01

    Commercial atomic frequency standards (AFS) are deployed in diverse civilian, military, and aerospace applications, ranging from high-precision measurement and calibration to navigation, communications and, of course, timekeeping. Currently, commercially available AFS include magnetically-selected cesium beam frequency standards and hydrogen masers and lamp-pumped rubidium oscillators. Despite the revolution in atomic physics and laboratory-scale AFS brought about by the advent of the tunable laser in the early 1970s, commercial AFS invariably rely on more conventional atomic physics technology developed in the 1950s. The reason for this lack of advancement of commercial AFS technology is the relatively poor reliability and environmental sensitivity of narrow-linewidth single-mode laser sources at atomic resonance wavelengths. Over the past 8 years, Symmetricom, in collaboration with laser manufacturers, has developed specialized laser sources for commercial AFS applications. These laser devices, optimized for high spectral purity and long-term reliability, will enable a new generation of commercial AFS. This talk will briefly describe two laser-based atomic frequency standard development programs at Symmetricom. The Chip-Scale Atomic Clock, two orders of magnitude smaller and lower power than any commercial AFS, will enable atomic timing accuracy in portable battery-powered applications. The Optically-Pumped Cesium Beam Frequency Standard, under development for deployment onboard the GPS-III satellite constellation, will provide enhanced short-term stability and longer lifetime compared to magnetically-selected cesium beam AFS.

  7. Rydberg Atom Quantum Hybrid Systems

    Science.gov (United States)

    Chao, Yuanxi; Sheng, Jiteng; Kumar, Santosh; Bigelow, Nicholas P.; Shaffer, James P.

    2017-04-01

    We report on our recent experimental and theoretical work with Rydberg atom-cavity and Rydberg atom-surface hybrid quantum systems. In the atom-cavity system, Rb contained in a dipole trap is transported into a high-finesse optical cavity using a focus-tunable lens. Cavity assisted Rydberg EIT is observed in the cavity transmission and used to characterize the electric fields in the cavity. The electric fields are attributed to surface adsorbates adhering to the cavity mirrors. We also investigate the coupling of a Rydberg atom ensemble to surface phonon polaritons (SPhPs) propagating on piezoelectric superlattices made from thin film ferroelectric materials. Strong coupling between the atomic and surface excitations can be achieved, due to the large Rydberg transition dipole moments and the local field enhancement of the SPhP modes. The system has many advantages for information transport since the atoms need only be placed at distances on the order of mms from the surface and the SPhPs do not couple to free space electro-magnetic fields. Experimental progress will be discussed, including the fabrication of submicron-period periodically poled Lithium Niobate using the direct e-beam writing technique. This work is supported by AFOSR.

  8. Beam diagnostics

    CERN Document Server

    Raich, U

    2006-01-01

    The instrumentation measuring beam parameters constitutes an important part of any particle accelerator. These lectures aim at giving an overview of detection and measurement techniques without going too much into details of implementation. Instruments for linear accelerators, transfer lines, and small synchrotrons are described with an emphasis on opportunities and problems specific to low-energy particle beams.

  9. Magnetic trapping of cold bromine atoms.

    Science.gov (United States)

    Rennick, C J; Lam, J; Doherty, W G; Softley, T P

    2014-01-17

    Magnetic trapping of bromine atoms at temperatures in the millikelvin regime is demonstrated for the first time. The atoms are produced by photodissociation of Br2 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 lost only 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.

  10. Beam optics of the folded tandem ion accelerator at BARC

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 59; Issue 1. Beam optics of the folded tandem ion accelerator ... 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 ...

  11. Beam diagnostics

    CERN Document Server

    Raich, U

    2008-01-01

    Most beam measurements are based on the electro-magnetic interaction of fields induced by the beam with their environment. Beam current transformers as well as beam position monitors are based on this principle. The signals induced in the sensors must be amplified and shaped before they are converted into numerical values. These values are further treated numerically in order to extract meaningful machine parameter measurements. The lecture introduces the architecture of an instrument and shows where in the treatment chain digital signal analysis can be introduced. Then the use of digital signal processing is presented using tune measurements, orbit and trajectory measurements as well as beam loss detection and longitudinal phase space tomography as examples. The hardware as well as the treatment algorithms and their implementation on Digital Signal Processors (DSPs) or in Field Programmable Gate Arrays (FPGAs) are presented.

  12. 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

  13. The nonequilibrium beam plasma

    Science.gov (United States)

    Skvortsov, V. A.

    1996-10-01

    The kinetics and the heating of nonequilibrium plasma, formed as a result of injection of intensive relativistic (or subrelativistic) electron or proton beams in the atomic-molecular gas (nitrogen or air with water vapor) at different pressures (from 0.1-10 atm) have been investigated numerically by using the mathematical model “SKIF” which was developed by the author 15 years ago. More than 200 plasma-chemical reactions and elementary processes are taken into consideration, including the action of “non-Maxwell” electrons of the cascade, formed in the ionization of the molecules by the beam particles. For the description of the deviation of energy distribution of such electrons from the equilibrium distribution, a simplified analytical model was used, with the help of which one can calculate the energy spectrum of the cascade electrons with satisfactory precision. This essentially reduces the calculating expenditure.

  14. Cesium Atomic Fountain Clocks at NMIJ

    Science.gov (United States)

    2010-11-01

    Wynands and S. Weyers, 2005, “Atomic fountain clocks,” Metrologia , 42, S64-S79. [2] M. Takamoto, F. L. Hong, R. Higashi, et al., 2005, “An optical...beam of laser-cooled cesium atoms,” Physical Review, A 60, R4241-R4244. [13] V. Gerginov, N. Nemitz, S. Weyers, et al., 2010, “Uncertainty evaluation of the caesium fountain clock PTB-CSF2,” Metrologia , 47, 65-79.

  15. 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)

  16. Matter-Wave Tractor Beams

    DEFF Research Database (Denmark)

    Gorlach, Alexey A.; Gorlach, Maxim A.; Lavrinenko, Andrei

    2017-01-01

    Optical and acoustic tractor beams are currently the focus of intense research due to their counterintuitive property of exerting a pulling force on small scattering objects. In this Letter we propose a matter-wave tractor beam and utilize the de Broglie waves of nonrelativistic matter particles...... in analogy to "classical" tractor beams. We reveal the presence of the quantum-mechanical pulling force for the variety of quantum mechanical potentials observing the resonant enhancement of the pulling effect under the conditions of the suppressed scattering known as the Ramsauer-Townsend effect. We also...... are compared, and the matter-wave pulling force is found to have exclusive properties of dragging slow particles in short-range potentials. We envisage that the use of tractor beams could lead to the unprecedented precision in manipulation with atomic-scale quantum objects....

  17. 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

  18. Production of Hydrated Metal Ions by Fast Ion or Atom Beam Sputtering. Collision-Induced Dissociation and Successive Hydration Energies of Gaseous Cu+ with 1-4 Water Molecules

    NARCIS (Netherlands)

    Magnera, Thomas F.; David, Donald E.; Stulik, Dusan; Orth, Robert G.; Jonkman, Harry T.; Michl, Josef

    1989-01-01

    Low-temperature sputtering of frozen aqueous solutions of metal salts, of hydrated crystalline transition-metal salts, of frosted metal surfaces, and of frosted metal salts with kiloelectronvolt energy rare gas atoms or ions produces copious amounts of cluster ions, among which M+(H2O)n and/or

  19. Pulsed metastable atom source for low vapour-pressure metals

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Urena, A.; Verdasco Costales, E. (Universidad Complutense de Madrid (Spain). Facultad de Quimica); Saez Rabanos, V. (Universidad Politecnica de Madrid (Spain). Escuela Tecnica Superior de Ingenieros Industriales)

    1990-03-01

    The basic design and most relevant experimental conditions of a pulsed metastable atomic-beam oven are described. The stainless steel oven is suitable for vaporising metals and salts up to around 1400 K producing intense beams of metastable alkaline-earth atoms when pulsed or continuous wave low voltage discharges are used. Several applications using atomic calcium in its {sup 3}P and {sup 1}D electronic state are reported. The beam characterisation and discharge efficiency have been measured by time-of-flight or laser-induced fluorescence techniques. In addition, a method of changing the metastable n{sup 3}P/n{sup 1}D ratio, by raising the oven temperature, is described which looks very promising for the study of electronic selectivity in reactive collision processes. Finally several spectroscopic applications for atomic and molecular beam determinations are reported. (author).

  20. Neutral Atom Lithography With Multi-Frequency Laser Fields

    National Research Council Canada - National Science Library

    Elliott, Daniel S; Janes, David B

    2006-01-01

    In this final report we describe our efforts in exposing self-assembled molecular monolayers to a beam of neutral sodium atoms and chemically etching the resulting substrate and characterization of the resulting surface...

  1. Beam collimator

    CERN Multimedia

    1977-01-01

    A four-block collimator installed on a control table for positioning the alignment reference marks. Designed for use with SPS secondary beams, the collimator operates under vacuum conditions. See Annual Report 1976 p. 121 and photo 7701014.

  2. High Atom Number in Microsized Atom Traps

    Science.gov (United States)

    2015-12-14

    Final Performance Report on ONR Grant N00014-12-1-0608 High atom number in microsized atom traps for the period 15 May 2012 through 14 September...TYPE Final Technical Report 3. DATES COVERED (From - To) 05/15/2012-09/14/2012 4. TITLE AND SUBTITLE High atom number in microsized atom traps...forces for implementing a small-footprint, large-number atom -chip instrument. Bichromatic forces rely on absorption and stimulated emission to produce

  3. Observation of relativistic antihydrogen atoms

    Energy Technology Data Exchange (ETDEWEB)

    Blanford, Glenn DelFosse

    1998-01-01

    An observation of relativistic antihydrogen atoms is reported in this dissertation. Experiment 862 at Fermi National Accelerator Laboratory observed antihydrogen atoms produced by the interaction of a circulating beam of high momentum (3 < p < 9 GeV/c) antiprotons and a jet of molecular hydrogen gas. Since the neutral antihydrogen does not bend in the antiproton source magnets, the detectors could be located far from the interaction point on a beamline tangent to the storage ring. The detection of the antihydrogen is accomplished by ionizing the atoms far from the interaction point. The positron is deflected by a magnetic spectrometer and detected, as are the back to back photons resulting from its annihilation. The antiproton travels a distance long enough for its momentum and time of flight to be measured accurately. A statistically significant sample of 101 antihydrogen atoms has been observed. A measurement of the cross section for {bar H}{sup 0} production is outlined within. The cross section corresponds to the process where a high momentum antiproton causes e{sup +} e{sup -} pair creation near a nucleus with the e{sup +} being captured by the antiproton. Antihydrogen is the first atom made exclusively of antimatter to be detected. The observation experiment's results are the first step towards an antihydrogen spectroscopy experiment which would measure the n = 2 Lamb shift and fine structure.

  4. Sub-Angstrom Atomic-Resolution Imaging of Heavy Atoms to Light Atoms

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, Michael A.; Shao-Horn, Yang

    2003-05-23

    Three decades ago John Cowley and his group at ASU achieved high-resolution electron microscope images showing the crystal unit cell contents at better than 4Angstrom resolution. Over the years, this achievement has inspired improvements in resolution that have enabled researchers to pinpoint the positions of heavy atom columns within the cell. More recently, this ability has been extended to light atoms as resolution has improved. Sub-Angstrom resolution has enabled researchers to image the columns of light atoms (carbon, oxygen and nitrogen) that are present in many complex structures. By using sub-Angstrom focal-series reconstruction of the specimen exit surface wave to image columns of cobalt, oxygen, and lithium atoms in a transition metal oxide structure commonly used as positive electrodes in lithium rechargeable batteries, we show that the range of detectable light atoms extends to lithium. HRTEM at sub-Angstrom resolution will provide the essential role of experimental verification for the emergent nanotech revolution. Our results foreshadow those to be expected from next-generation TEMs with Cs-corrected lenses and monochromated electron beams.

  5. High energy density physics with intense ion and laser beams. Annual report 2003

    Energy Technology Data Exchange (ETDEWEB)

    Weyrich, K. (comp.)

    2004-07-01

    The following topics are dealt with: Laser plasma physics, plasma spectroscopy, beam interaction experiments, atomic and radiation physics, pulsed power applications, beam transport and accelerator research and development, properties of dense plasma, instabilities in beam-plasma interaction, beam transport in dense plasmas, short-pulse laser-matter interaction. (HSI)

  6. Atomic lithium vapor laser isotope separation

    CERN Document Server

    Olivares, I E

    2002-01-01

    An atomic vapor laser isotope separation in lithium was performed using tunable diode lasers. The method permits also the separation of the isotopes between the sup 6 LiD sub 2 and the sup 7 LiD sub 1 lines using a self-made mass separator which includes a magnetic sector and an ion beam designed for lithium. (Author)

  7. Nano-soldering to single atomic layer

    Science.gov (United States)

    Girit, Caglar O [Berkeley, CA; Zettl, Alexander K [Kensington, CA

    2011-10-11

    A simple technique to solder submicron sized, ohmic contacts to nanostructures has been disclosed. The technique has several advantages over standard electron beam lithography methods, which are complex, costly, and can contaminate samples. To demonstrate the soldering technique graphene, a single atomic layer of carbon, has been contacted, and low- and high-field electronic transport properties have been measured.

  8. Trapping cold molecules and atoms: Simultaneous magnetic deceleration and trapping of cold molecular Oxygen with Lithium atoms

    Science.gov (United States)

    Akerman, Nitzan; Karpov, Michael; Segev, Yair; Bibelink, Natan; Narevicius, Julia; Narevicius, Edvardas

    2016-05-01

    Cooling molecules to the ultra-cold regime remains a major challenge in the growing field of cold molecules. The molecular internal degrees of freedom complicate the effort of direct application of laser cooling. An alternative and general path towards ultra-cold molecules relies on sympathetic cooling via collisions with laser-cooled atoms. Here, we demonstrate the first step towards application of sympathetic cooling by co-trapping of molecular Oxygen with Lithium atoms in a magnetic trap at a temperature of 300 mK. Our experiment begins with a pulsed supersonic beam which is a general source for cold high-flux atomic and molecular beams. Although the supersonic expansion efficiently cools the beam to temperatures below 1K, it also accelerates the beam to high mean velocities. We decelerate a beam of O2 in a moving magnetic trap decelerator from 375 m/s to a stop. We entrained the molecular beam with Li atoms by laser ablation prior to deceleration. The deceleration ends with loading the molecules and atoms into a static quadrupole trap, which is generated by two permanent magnets. We estimate 109 trapped molecules with background limited lifetime of 0.6 Sec. Our achievement enables application of laser cooling on the Li atoms in order to sympathetically cool the O2.

  9. Molecular-beam scattering

    Energy Technology Data Exchange (ETDEWEB)

    Vernon, M.F.

    1983-07-01

    The molecular-beam technique has been used in three different experimental arrangements to study a wide range of inter-atomic and molecular forces. Chapter 1 reports results of a low-energy (0.2 kcal/mole) elastic-scattering study of the He-Ar pair potential. The purpose of the study was to accurately characterize the shape of the potential in the well region, by scattering slow He atoms produced by expanding a mixture of He in N/sub 2/ from a cooled nozzle. Chapter 2 contains measurements of the vibrational predissociation spectra and product translational energy for clusters of water, benzene, and ammonia. The experiments show that most of the product energy remains in the internal molecular motions. Chapter 3 presents measurements of the reaction Na + HCl ..-->.. NaCl + H at collision energies of 5.38 and 19.4 kcal/mole. This is the first study to resolve both scattering angle and velocity for the reaction of a short lived (16 nsec) electronic excited state. Descriptions are given of computer programs written to analyze molecular-beam expansions to extract information characterizing their velocity distributions, and to calculate accurate laboratory elastic-scattering differential cross sections accounting for the finite apparatus resolution. Experimental results which attempted to determine the efficiency of optically pumping the Li(2/sup 2/P/sub 3/2/) and Na(3/sup 2/P/sub 3/2/) excited states are given. A simple three-level model for predicting the steady-state fraction of atoms in the excited state is included.

  10. "Bohr's Atomic Model."

    Science.gov (United States)

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  11. International Conference on The Physics of Highly Ionised Atoms, Incorporating the International Conference on Beam Foil Spectroscopy (7th), Held in England on July 2 - 5, 1984. Programme and Abstracts

    Science.gov (United States)

    1984-07-05

    Strong Fields" 0 G Soff 9.35 "Population Inversions and Gain for X-ray Lasers" 24 R E Elton 10.10 COFFEE 10.40 "Heavy Ion Beam Puo.iped Lasers" 25 D E Mv...Dumont, P. D. 30 Duong, H. T. 67 Duval, B. P. 77, 92 E Ekberg, J. 0. 29 . Elton , R. E. 24 Engstr~m, L. 65, 66 Ermolaev, A. M. 78 F Fairley, N. A. 91...AGRIPPA FACILITY S. Bliman, J.J. Bonnet, A. Bordenave-Montesquieu, J. Desesquelles, 0 M. Druetta, D. Hitz & M. Mayo AGRIPPA GIS CEA/CNRS, Centre d’Etudes

  12. ALCBEAM - Neutral beam formation and propagation code for beam-based plasma diagnostics

    Science.gov (United States)

    Bespamyatnov, I. O.; Rowan, W. L.; Liao, K. T.

    2012-03-01

    ALCBEAM is a new three-dimensional neutral beam formation and propagation code. It was developed to support the beam-based diagnostics installed on the Alcator C-Mod tokamak. The purpose of the code is to provide reliable estimates of the local beam equilibrium parameters: such as beam energy fractions, density profiles and excitation populations. The code effectively unifies the ion beam formation, extraction and neutralization processes with beam attenuation and excitation in plasma and neutral gas and beam stopping by the beam apertures. This paper describes the physical processes interpreted and utilized by the code, along with exploited computational methods. The description is concluded by an example simulation of beam penetration into plasma of Alcator C-Mod. The code is successfully being used in Alcator C-Mod tokamak and expected to be valuable in the support of beam-based diagnostics in most other tokamak environments. Program summaryProgram title: ALCBEAM Catalogue identifier: AEKU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKU_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 66 459 No. of bytes in distributed program, including test data, etc.: 7 841 051 Distribution format: tar.gz Programming language: IDL Computer: Workstation, PC Operating system: Linux RAM: 1 GB Classification: 19.2 Nature of problem: Neutral beams are commonly used to heat and/or diagnose high-temperature magnetically-confined laboratory plasmas. An accurate neutral beam characterization is required for beam-based measurements of plasma properties. Beam parameters such as density distribution, energy composition, and atomic excited populations of the beam atoms need to be known. Solution method: A neutral beam is initially formed as an ion beam which is extracted from

  13. Scattering of Slow Metastable Argon Atoms by Dielectric Nanospheres

    Science.gov (United States)

    Baudon, J.; Hamamda, M.; Grucker, J.; Perales, F.; Dutier, G.; Ducloy, M.; Bocvarski, V.

    2009-11-01

    The elastic scattering at low energy of metastable argon atoms with internal angular momentum J = 0 and 2 by dielectric nanospheres is investigated. The differential cross sections are calculated for both isotropic and anisotropic interactions. A polarization effect is clearly evidenced. The possible use of a metastable atom beam as a probe of an ensemble of nanospheres deposited on a passive substrate is examined.

  14. Atom Optics for Bose-Einstein Condensates (BEC)

    Science.gov (United States)

    2012-04-25

    CONTRACT NUMBER Atom Optics for Bose-Einstein Condensates (BEC) 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Matthew B...free space fountain and beam configurations, that utilize light pulses to manipulate the atoms, have demonstrated the greatest sensitivities [1, 2, 3

  15. Atomic frequency standard relativistic Doppler shift experiment

    Science.gov (United States)

    Peters, H. E.; Reinhardt, V. S.

    1974-01-01

    An experiment has been performed to measure possible space anisotropy as it would effect the frequency of a cesium atomic beam standard clock in a laboratory on earth due to motion relative to external coordinate frames. The cesium frequency was measured as a function of orientation with respect to an atomic hydrogen maser standard. Over a period of 34 days 101 measurements were made. The results are consistent with a conclusion that no general orientation dependance attributable to spacial anisotropy was observed. It is shown that both the airplane clock results, and the null results for the atomic beam clock, are consistent with Einstein general or special relativity, or with the Lorentz transformations alone.

  16. Superresolution beams

    CSIR Research Space (South Africa)

    Ngcobo, S

    2012-07-01

    Full Text Available stream_source_info Ngcobo2_2012.pdf.txt stream_content_type text/plain stream_size 3697 Content-Encoding ISO-8859-1 stream_name Ngcobo2_2012.pdf.txt Content-Type text/plain; charset=ISO-8859-1 SUPERRESOLUTION BEAMS S... University of Johannesburg, PO Box 524, Auckland Park, 2006, South Africa Slide 2 ? CSIR 2011 www.csir.co.za Outline ? Introduction ? Concept of superresolution beams ? Transformation of TEM00 to TEM10 ? Resonator...

  17. Superresolution beams

    CSIR Research Space (South Africa)

    Ngcobo, S

    2011-11-01

    Full Text Available stream_source_info Ngcobo3_2012.pdf.txt stream_content_type text/plain stream_size 4467 Content-Encoding ISO-8859-1 stream_name Ngcobo3_2012.pdf.txt Content-Type text/plain; charset=ISO-8859-1 SUPERRESOLUTION BEAMS S... 2011 www.csir.co.za Outline ? Introduction ? Concept of superresolution beams ? Transformation of TEM00 to TEM10 ? Resonator design and experimental setup ? Results ? Conclusions ? Future work Slide 3 ? CSIR 2011...

  18. Off-axis excitation of hydrogenlike atoms by twisted photons

    Science.gov (United States)

    Afanasev, Andrei; Carlson, Carl E.; Mukherjee, Asmita

    2013-09-01

    We show that the twisted-photon states, or photon states with large (>ℏ) angular momentum projection (mγ) in the direction of motion, can photoexcite atomic levels for a hydrogenlike atom that are novel and distinct and are not restricted by mγ, when the symmetry axis of the twisted-photon beam does not coincide with the center of the atomic target. Selection rules are given and interesting implications and observables for the above process are pointed out.

  19. Teach us atom structure

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Suh Yeon

    2006-08-15

    This book is written to teach atom structure in very easy way. It is divided into nine chapters, which indicates what is the components of matter? when we divide matter continuously, it becomes atom, what did atom look like? particles comprised of matter is not only atom, discover of particles comprised of atom, symbol of element, various radiation, form alchemy to nuclear transmutation, shape of atom is evolving. It also has various pictures in each chapters to explain easily.

  20. Playing pinball with atoms.

    Science.gov (United States)

    Saedi, Amirmehdi; van Houselt, Arie; van Gastel, Raoul; Poelsema, Bene; Zandvliet, Harold J W

    2009-05-01

    We demonstrate the feasibility of controlling an atomic scale mechanical device by an external electrical signal. On a germanium substrate, a switching motion of pairs of atoms is induced by electrons that are directly injected into the atoms with a scanning tunneling microscope tip. By precisely controlling the tip current and distance we make two atom pairs behave like the flippers of an atomic-sized pinball machine. This atomic scale mechanical device exhibits six different configurations.

  1. Status of Beam Diagnostic Systems for the PEFP

    CERN Document Server

    Park Jang Ho; Choi Byung Ho; Ha Hwang Woon; Han, Sang-Hyo; Park, Sung-Ju; Woon Parc, Yong; Yun Huang Jung

    2005-01-01

    A proton linear accelerator is currently the construction at the KAERI (Korea Atomic Research Institute) to the PEFP (Proton Engineering Frontier Project) in Korea. We are accomplished the technique development of beam diagnostic system to be currently the construction. We treat beam diagnostics for the high power proton linear accelerator. Prototype beam position & phase monitor (BPPM) electronics was made and tested successfully in one of the beam diagnostic systems. The beam position monitor pickup electrode is a capacitive type (electrostatic type) which has a button form. Button form electrode, in common use around electron synchrotrons and storage rings, are a variant of the electrode with small button form (e.g., sub mm diameter). However, we are designed button form electrode to measure beam position of proton beam. The BCM (Beam Current Monitor) is developed Tuned CT (Current Transformer) for collaborate with Bergoz Instruments. This paper describes the status of beam diagnostic systems for the P...

  2. Compact magneto-optical sources of slow atoms

    OpenAIRE

    Ovchinnikov, Yuri B.

    2004-01-01

    Three different configurations of compact magneto-optical sources of slow Rb atoms(LVIS, 2D(+)-MOT and 2D-MOT) were compared with each other at fixed geometry of cooling laser beams. A precise control of the intensity balances between the four separate transverse cooling laser beams provided a total continuous flux of cold atoms from the LVIS and 2D(+)-MOT sources about 8x10^9 atoms/s at total laser power of 60 mW. The flux was measured directly from the loading rate of a 3D-MOT, placed 34 cm...

  3. Measurement of the hyperfine structure of antihydrogen in a beam

    CERN Document Server

    Widmann, E.; Juhasz, B.; Malbrunot, C.; Massiczek, O.; Sauerzopf, C.; Suzuki, K.; Wunschek, B.; Zmeskal, J.; Federmann, S.; Kuroda, N.; Ulmer, S.; Yamazaki, Y.

    2013-01-01

    A measurement of the hyperfine structure of antihydrogen promises one of the best tests of CPT symmetry. We describe an experiment planned at the Antiproton Decelerator of CERN to measure this quantity in a beam of slow antihydrogen atoms.

  4. Status of positron beams for dark photons experiments

    Directory of Open Access Journals (Sweden)

    Valente Paolo

    2017-01-01

    Full Text Available High energy positron beams are an important tool for fixed-target experiments searching for new particles produced in the annihilation on atomic electrons of a target. The status of existing or planned infrastructures is reviewed.

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

    Directory of Open Access Journals (Sweden)

    Trimèche A.

    2015-01-01

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

  6. Generation of High Quality Laser Accelerated Ion Beams

    OpenAIRE

    Esirkepov, T. Zh.; Bulanov, S. V.; Nishihara, K.; Tajima, T.; Pegoraro, F.; Khoroshkov, V. S.; Mima, K.; Daido, H.; Kato, Y.; Kitagawa, Y.; Nagai, K.; Sakabe, S.

    2002-01-01

    In order to achieve a high quality, i. e. monoergetic, intense ion beam, we propose the use of a double layer target. The first layer, at the target front, consists of high-Z atoms, while the second (rear) layer is a thin coating of low-Z atoms. The high quality proton beams from the double layer target, irradiated by an ultra-intense laser pulse, are demonstrated with three dimensional Particle-in-Cell simulations.

  7. Control the fear atomic

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Gwan [I and Book, Seoul (Korea, Republic of)

    2003-04-15

    This book has a lot of explanation of nuclear energy with articles. Their titles are the bad man likes atomic, the secret of atom, nuclear explosion, NPT?, the secret of uranium fuel rod, nuclear power plant vs nuclear bomb, I hate atomic, keep plutonium in control, atomic in peace and find out alternative energy.

  8. Formation of positron-atom bound states in collisions between Rydberg Ps and neutral atoms

    CERN Document Server

    Swann, A R; Deller, A; Gribakin, G F

    2016-01-01

    Predicted twenty years ago, positron binding to neutral atoms has not yet been observed experimentally. A new scheme is proposed to detect positron-atom bound states by colliding Rydberg positronium (Ps) with neutral atoms. Estimates of the charge-transfer-reaction cross section are obtained using the first Born approximation for a selection of neutral atom targets and a wide range of incident Ps energies and principal quantum numbers. We also estimate the corresponding Ps ionization cross section. The accuracy of the calculations is tested by comparison with earlier predictions for Ps charge transfer in collisions with hydrogen and antihydrogen. We describe an existing Rydberg Ps beam suitable for producing positron-atom bound states and estimate signal rates based on the calculated cross sections and realistic experimental parameters. We conclude that the proposed methodology is capable of producing such states and of testing theoretical predictions of their binding energies.

  9. A Compact Microchip-Based Atomic Clock Based on Ultracold Trapped Rb Atoms

    CERN Document Server

    Farkas, Daniel M; Anderson, Dana Z

    2009-01-01

    We propose a compact atomic clock based on ultracold Rb atoms that are magnetically trapped near the surface of an atom microchip. An interrogation scheme that combines electromagnetically-induced transparency (EIT) with Ramsey's method of separated oscillatory fields can achieve atomic shot-noise level performance of 10^{-13}/sqrt(tau) for 10^6 atoms. The EIT signal can be detected with a heterodyne technique that provides noiseless gain; with this technique the optical phase shift of a 100 pW probe beam can be detected at the photon shot-noise level. Numerical calculations of the density matrix equations are used to identify realistic operating parameters at which AC Stark shifts are eliminated. By considering fluctuations in these parameters, we estimate that AC Stark shifts can be canceled to a level better than 2*10^{-14}. An overview of the apparatus is presented with estimates of duty cycle and power consumption.

  10. Placing single atoms in graphene with a scanning transmission electron microscope

    Science.gov (United States)

    Dyck, Ondrej; Kim, Songkil; Kalinin, Sergei V.; Jesse, Stephen

    2017-09-01

    We employ the sub-atomically focused beam of a scanning transmission electron microscope (STEM) to introduce and controllably manipulate individual dopant atoms in a 2D graphene lattice. The electron beam is used to create defects and subsequently sputter adsorbed source materials into the graphene lattice such that individual vacancy defects are controllably passivated by Si substitutional atoms. We further document that Si point defects may be directed through the lattice via e-beam control or modified (as yet, uncontrollably) to form new defects which can incorporate new atoms into the graphene lattice. These studies demonstrate the potential of STEM for atom-by-atom nanofabrication and fundamental studies of chemical reactions in 2D materials on the atomic level.

  11. Atomic Models for Motional Stark Effects Diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Gu, M F; Holcomb, C; Jayakuma, J; Allen, S; Pablant, N A; Burrell, K

    2007-07-26

    We present detailed atomic physics models for motional Stark effects (MSE) diagnostic on magnetic fusion devices. Excitation and ionization cross sections of the hydrogen or deuterium beam traveling in a magnetic field in collisions with electrons, ions, and neutral gas are calculated in the first Born approximation. The density matrices and polarization states of individual Stark-Zeeman components of the Balmer {alpha} line are obtained for both beam into plasma and beam into gas models. A detailed comparison of the model calculations and the MSE polarimetry and spectral intensity measurements obtained at the DIII-D tokamak is carried out. Although our beam into gas models provide a qualitative explanation for the larger {pi}/{sigma} intensity ratios and represent significant improvements over the statistical population models, empirical adjustment factors ranging from 1.0-2.0 must still be applied to individual line intensities to bring the calculations into full agreement with the observations. Nevertheless, we demonstrate that beam into gas measurements can be used successfully as calibration procedures for measuring the magnetic pitch angle through {pi}/{sigma} intensity ratios. The analyses of the filter-scan polarization spectra from the DIII-D MSE polarimetry system indicate unknown channel and time dependent light contaminations in the beam into gas measurements. Such contaminations may be the main reason for the failure of beam into gas calibration on MSE polarimetry systems.

  12. The Screening Effect in Electromagnetic Production of Electron Positron Pairs in Relativistic Nucleus-Atom Collisions

    Science.gov (United States)

    Wu, Jianshi; Derrickson, J. H.; Parnell, T. A.; Strayer, M. R.

    1999-01-01

    We study the screening effects of the atomic electrons in the electromagnetic production of electron-positron pairs in relativistic nucleus-atom collisions for fixed target experiments. Our results are contrasted with those obtained in bare collisions, with particular attention given to its dependence on the beam energy and the target atom.

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

    CERN Document Server

    Tolstikhina, Inga; Winckler, Nicolas; Shevelko, Viacheslav

    2018-01-01

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

  14. Helium ion beam induced growth of hammerhead AFM probes

    NARCIS (Netherlands)

    Nanda, G.; Van Veldhoven, E.; Maas, D.; Sadeghian, H.; Alkemade, P.F.A.

    2015-01-01

    The authors report the direct-write growth of hammerhead atomic force microscope(AFM) probes by He+beam induced deposition of platinum-carbon. In order to grow a thin nanoneedle on top of a conventional AFM probe, the authors move a focused He+beam during exposure to a PtC precursor gas. In the

  15. Compact Measurement Station for Low Energy Proton Beams

    CERN Document Server

    Yildiz, H.

    2017-02-24

    A compact, remote controlled, cost efficient diagnostic station has been developed to measure the charge, the profile and the emittance for low energy proton beams. It has been installed and tested in the proton beam line of the Project Prometheus at SANAEM of the Turkish Atomic Energy Authority.

  16. Structuring of silicon with low energy focused ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Nebiker, P.W.; Doebeli, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Muehle, R. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    The defect production in silicon induced by focused ion beam irradiation as a function of energy and projectile mass has been investigated and compared to the measured sputter yield. The aim was to find optimal beam parameters for the structuring of semiconductors with a minimum amount of defects produced per removed atom. (author) 2 figs., 2 refs.

  17. Helium ion beam induced growth of hammerhead AFM probes

    NARCIS (Netherlands)

    Nanda, G.; Veldhoven, E. van; Maas, D.J.; Sadeghian Marnani, H.; Alkemade, P.F.A.

    2015-01-01

    The authors report the direct-write growth of hammerhead atomic force microscope (AFM) probes by He+ beam induced deposition of platinum-carbon. In order to grow a thin nanoneedle on top of a conventional AFM probe, the authors move a focused He+ beam during exposure to a PtC precursor gas. In the

  18. Atom Probe Tomography of Geomaterials

    Science.gov (United States)

    Parman, S. W.; Diercks, D.; Gorman, B.; Cooper, R. F.

    2013-12-01

    From the electron microprobe to the secondary ion microprobe to laser-ablation ICP-MS, steady improvements in the spatial resolution and detection limits of geochemical micro-analysis have been central to generating new discoveries. Atom probe tomography (APT) is a relatively new technology that promises nm-scale spatial resolution (in three dimensions) with ppm level detection limits. The method is substantially different from traditional beam-based (electron, ion, laser) methods. In APT, the sample is shaped (usually with a dual-beam FIB) into a needle with typical dimensions of 1-2 μm height and 100-200 nm diameter. Within the atom probe, the needle is evaporated one atom (ideally) at a time by a high electric field (ten's of V per square nm at the needle tip). A femtosecond laser (12 ps pulse width) is used to assist in evaporating non-conducting samples. The two-dimensional detector locates where the atom was released from the needle's surface and so can reconstruct the positions of all detected atoms in three dimensions. It also records the time of flight of the ion, which is used to calculate the mass/charge ratio of the ion. We will discuss our results analyzing a range of geologic materials. In one case, naturally occurring platinum group alloys (PGA) from the Josephine Ophiolite have been imaged. Such alloys are of interest as recorders of the Os heterogeneity of the mantle [1,2]. Optimal ablation was achieved with a laser power of 120-240 pJ and laser pulse rates 500 kHz. Runs were stopped after 10 million atoms were imaged. An example analysis is: Pt 61(1), Fe 26.1(9), Rh 1.20(4), Ir 7.0(7), Ni 2.65(8), Ru 0.20(9), Cu 1.22(8), Co 0.00029(5). Values are in atomic %; values in parentheses are one-sigma standard deviations on five separate needles from the same FIB lift-out, which was 30 μm long. Assuming the sample is homogenous over the 30 μm from which the needle was extracted, the analyses suggest relative errors for major elements below 5% and for

  19. Atom slowing via dispersive optical interactions

    Science.gov (United States)

    Hamamda, M.; Boustimi, M.; Correia, F.; Baudon, J.; Taillandier-Loize, T.; Dutier, G.; Perales, F.; Ducloy, M.

    2012-02-01

    A promising technique of atom slowing is proposed. It is based upon the dispersive interaction of atoms with optical potential pulses generated by a far-off-resonance standing wave modulated in time. Each pulse reduces the velocity by a small amount. By repeating the process thousands of times, the velocity can be lowered from several hundreds of meters per second down to almost zero, over a path as short as 20cm. In the absence of any random recoil process, the initial characteristics of the beam are preserved.

  20. Microfabricated Waveguide Atom Traps.

    Energy Technology Data Exchange (ETDEWEB)

    Jau, Yuan-Yu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

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

  1. Atomic and molecular manipulation

    CERN Document Server

    Mayne, Andrew J

    2011-01-01

    Work with individual atoms and molecules aims to demonstrate that miniaturized electronic, optical, magnetic, and mechanical devices can operate ultimately even at the level of a single atom or molecule. As such, atomic and molecular manipulation has played an emblematic role in the development of the field of nanoscience. New methods based on the use of the scanning tunnelling microscope (STM) have been developed to characterize and manipulate all the degrees of freedom of individual atoms and molecules with an unprecedented precision. In the meantime, new concepts have emerged to design molecules and substrates having specific optical, mechanical and electronic functions, thus opening the way to the fabrication of real nano-machines. Manipulation of individual atoms and molecules has also opened up completely new areas of research and knowledge, raising fundamental questions of "Optics at the atomic scale", "Mechanics at the atomic scale", Electronics at the atomic scale", "Quantum physics at the atomic sca...

  2. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    2000-01-01

    This fifth volume of the successful series Advances in Atomic Spectroscopy continues to discuss and investigate the area of atomic spectroscopy.It begins with a description of the use of various atomic spectroscopic methods and applications of speciation studies in atomic spectroscopy. The emphasis is on combining atomic spectroscopy with gas and liquid chromatography. In chapter two the authors describe new developments in tunable lasers and the impact they will have on atomic spectroscopy. The traditional methods of detection, such as photography and the photomultiplier, and how they are being replaced by new detectors is discussed in chapter three. The very active area of glow discharge atomic spectrometry is presented in chapter four where, after a brief introduction and historical review, the use of glow discharge lamps for atomic spectroscopy and mass spectrometry are discussed. Included in this discussion is geometry and radiofrequency power. The future of this source in atomic spectroscopy is also dis...

  3. Stable beams

    CERN Multimedia

    2015-01-01

    Stable beams: two simple words that carry so much meaning at CERN. When LHC page one switched from "squeeze" to "stable beams" at 10.40 a.m. on Wednesday, 3 June, it triggered scenes of jubilation in control rooms around the CERN sites, as the LHC experiments started to record physics data for the first time in 27 months. This is what CERN is here for, and it’s great to be back in business after such a long period of preparation for the next stage in the LHC adventure.   I’ve said it before, but I’ll say it again. This was a great achievement, and testimony to the hard and dedicated work of so many people in the global CERN community. I could start to list the teams that have contributed, but that would be a mistake. Instead, I’d simply like to say that an achievement as impressive as running the LHC – a machine of superlatives in every respect – takes the combined effort and enthusiasm of everyone ...

  4. Atoms in the counter-propagating frequency-modulated waves: splitting, cooling, confinement

    Science.gov (United States)

    Romanenko, Victor I.; Kornilovska, Nataliya V.

    2017-09-01

    We show that the counter-propagating frequency-modulated (FM) waves of the same intensity can split an orthogonal atomic beam into two beams. We calculate the temperature of the atomic ensemble for the case when the atoms are grouped around zero velocity in the direction of the waves propagation. The high-intensity laser radiation with a properly chosen carrier frequency can form a one-dimensional trap for atoms. We carry out the numerical simulation of the atomic motion (two-level model of the atom-field interaction) using parameters appropriate for sodium atoms and show that sub-Doppler cooling can be reached. We suppose that such a cooling is partly based on the cooling without spontaneous emission in polychromatic waves [H. Metcalf, Phys. Rev. A 77, 061401 (2008)]. We calculate the state of the atom in the field by the Monte Carlo wave-function method and describe its mechanical motion by the classical mechanics.

  5. Atomic vapor density monitor

    Energy Technology Data Exchange (ETDEWEB)

    Sewall, N.; Harris, W.; Beeler, R.; Wooldridge, J.; Chen, H.L.

    1986-09-01

    This report presents information on the Atomic Vapor Density Monitor (AVDM) system that measures the density of a vapor by measuring the absorption of light from a swept-wavelength laser that passes through an atomic vapor stream.

  6. Atomic Spectra Database (ASD)

    Science.gov (United States)

    SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

  7. Playing Pinball with Atoms

    NARCIS (Netherlands)

    Saedi, A.; van Houselt, Arie; van Gastel, Raoul; Poelsema, Bene; Zandvliet, Henricus J.W.

    2009-01-01

    We demonstrate the feasibility of controlling an atomic scale mechanical device by an external electrical signal. On a germanium substrate, a switching motion of pairs of atoms is induced by electrons that are directly injected into the atoms with a scanning tunneling microscope tip. By precisely

  8. Fragmentation in Carbon Therapy Beams

    CERN Document Server

    Charara, Y M

    2010-01-01

    The state of the art Monte Carlo code HETC-HEDS was used to simulate spallation products, secondary neutron, and secondary proton production in A-150 Tissue Equivalent Plastic phantoms to investigate fragmentation of carbon therapy beams. For a 356 MeV/Nucleon carbon ion beam, production of charged particles heavier than protons was 0.24 spallation products per incident carbon ion with atomic numbers ranging from 1 through 5 (hydrogen to boron). In addition, there were 4.73 neutrons and 2.95 protons produced per incident carbon ion. Furthermore, as the incident energy increases, the neutron production rate increases at a rate of 20% per 10 MeV/nucleon. Secondary protons were created at a rate between 2.62-2.87 per carbon ion, while spallation products were created at a rate between 0.20-0.24 per carbon ion.

  9. Atomization characteristics of a prefilming airblast atomizer

    Science.gov (United States)

    Hayashi, Shigeru; Koito, Atsushi; Hishiki, Manabu

    1992-01-01

    The size distribution of water test sprays generated by a prefilming airblast atomizer used for aeroengines was measured in swirling and non-swirling flows with the well established laser scattering particle sizing technique. Atomizing air velocity (or pressure difference) was varied in a range wider than the conditions of actual engines. The Sauter Mean Diameter (SMD) decreased at approximately a 1.5 power of the atomizing air velocity, being a higher velocity index than the previously reported values of 1 to 1.2. It was unexpectedly found that the effect of the liquid/air flow ratio was small. Since swirling flow increased the SMD at lower air velocities yet decreased it at higher ones, it is suggested that the reverse flow near the nozzle pintle adversely affects atomization.

  10. Single atom electrochemical and atomic analytics

    Science.gov (United States)

    Vasudevan, Rama

    In the past decade, advances in electron and scanning-probe based microscopies have led to a wealth of imaging and spectroscopic data with atomic resolution, yielding substantial insight into local physics and chemistry in a diverse range of systems such as oxide catalysts, multiferroics, manganites, and 2D materials. However, typical analysis of atomically resolved images is limited, despite the fact that image intensities and distortions of the atoms from their idealized positions contain unique information on the physical and chemical properties inherent to the system. Here, we present approaches to data mine atomically resolved images in oxides, specifically in the hole-doped manganite La5/8Ca3/8MnO3, on epitaxial films studied by in-situ scanning tunnelling microscopy (STM). Through application of bias to the STM tip, atomic-scale electrochemistry is demonstrated on the manganite surface. STM images are then further analyzed through a suite of algorithms including 2D autocorrelations, sliding window Fourier transforms, and others, and can be combined with basic thermodynamic modelling to reveal relevant physical and chemical descriptors including segregation energies, existence and strength of atomic-scale diffusion barriers, surface energies and sub-surface chemical species identification. These approaches promise to provide tremendous insights from atomically resolved functional imaging, can provide relevant thermodynamic parameters, and auger well for use with first-principles calculations to yield quantitative atomic-level chemical identification and structure-property relations. This research was sponsored by the Division of Materials Sciences and Engineering, BES, DOE. Research was conducted at the Center for Nanophase Materials Sciences, which also provided support and is a DOE Office of Science User Facility.

  11. Topics in atomic hydrogen standard research and applications

    Science.gov (United States)

    Peters, H. E.

    1971-01-01

    Hydrogen maser based frequency and time standards have been in continuous use at NASA tracking stations since February 1970, while laboratory work at Goddard has continued in the further development and improvement of hydrogen masers. Concurrently, experimental work has been in progress with a new frequency standard based upon the hydrogen atom using the molecular beam magnetic resonance method. Much of the hydrogen maser technology is directly applicable to the new hydrogen beam standard, and calculations based upon realistic data indicate that the accuracy potential of the hydrogen atomic beam exceeds that of either the cesium beam tube or the hydrogen maser, possibly by several orders of magnitude. In addition, with successful development, the hydrogen beam standard will have several other performance advantages over other devices, particularly exceptional stability and long continuous operating life. Experimental work with a new laboratory hydrogen beam device has recently resulted in the first resonance transition curves, measurements of relative state populations, beam intensities, etc. The most important aspects of both the hydrogen maser and the hydrogen beam work are covered.

  12. Multilevel Atomic Coherent States and Atomic Holomorphic Representation

    Science.gov (United States)

    Cao, Chang-Qi; Haake, Fritz

    1996-01-01

    The notion of atomic coherent states is extended to the case of multilevel atom collective. Based on atomic coherent states, a holomorphic representation for atom collective states and operators is defined. An example is given to illustrate its application.

  13. Stochastic electrodynamics simulations for collective atom response in optical cavities

    Science.gov (United States)

    Lee, Mark D.; Jenkins, Stewart D.; Bronstein, Yael; Ruostekoski, Janne

    2017-08-01

    We study the collective optical response of an atomic ensemble confined within a single-mode optical cavity by stochastic electrodynamics simulations that include the effects of atomic position correlations, internal level structure, and spatial variations in cavity coupling strength and atom density. In the limit of low light intensity, the simulations exactly reproduce the full quantum field-theoretical description for cold stationary atoms and at higher light intensities we introduce semiclassical approximations to atomic saturation that we compare with the exact solution in the case of two atoms. We find that collective subradiant modes of the atoms, with very narrow linewidths, can be coupled to the cavity field by spatial variation of the atomic transition frequency and resolved at low intensities, and show that they can be specifically driven by tailored transverse pumping beams. We show that the cavity optical response, in particular both the subradiant mode profile and the resonance shift of the cavity mode, can be used as a diagnostic tool for the position correlations of the atoms and hence the atomic quantum many-body phase. The quantum effects are found to be most prominent close to the narrow subradiant mode resonances at high light intensities. Although an optical cavity can generally strongly enhance quantum fluctuations via light confinement, we show that the semiclassical approximation to the stochastic electrodynamics model provides at least a qualitative agreement with the exact optical response outside the subradiant mode resonances even in the presence of significant saturation of the atoms.

  14. Theory and applications of atomic and ionic polarizabilities

    Energy Technology Data Exchange (ETDEWEB)

    Mitroy, J [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Safronova, M S [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Clark, Charles W, E-mail: jxm107@rsphysse.anu.edu.a, E-mail: msafrono@udel.ed, E-mail: charles.clark@nist.go [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, MD 20899-8410 (United States)

    2010-10-28

    Atomic polarization phenomena impinge upon a number of areas and processes in physics. The dielectric constant and refractive index of any gas are examples of macroscopic properties that are largely determined by the dipole polarizability. When it comes to microscopic phenomena, the existence of alkaline-earth anions and the recently discovered ability of positrons to bind to many atoms are predominantly due to the polarization interaction. An imperfect knowledge of atomic polarizabilities is presently looming as the largest source of uncertainty in the new generation of optical frequency standards. Accurate polarizabilities for the group I and II atoms and ions of the periodic table have recently become available by a variety of techniques. These include refined many-body perturbation theory and coupled-cluster calculations sometimes combined with precise experimental data for selected transitions, microwave spectroscopy of Rydberg atoms and ions, refractive index measurements in microwave cavities, ab initio calculations of atomic structures using explicitly correlated wavefunctions, interferometry with atom beams and velocity changes of laser cooled atoms induced by an electric field. This review examines existing theoretical methods of determining atomic and ionic polarizabilities, and discusses their relevance to various applications with particular emphasis on cold-atom physics and the metrology of atomic frequency standards. (topical review)

  15. Scattering of muonic hydrogen atoms

    Energy Technology Data Exchange (ETDEWEB)

    Mulhauser, F. [Universite de Fribourg (Switzerland); Adamczak, A. [Institute of Nuclear Physics (Poland); Beer, G.A. [University of Victoria (Canada); Bystritsky, V.M. [Joint Institute for Nuclear Research (Russian Federation); Filipowicz, M. [Institute of Physics and Nuclear Techniques (Poland); Fujiwara, M.C. [University of British Columbia (Canada); Huber, T.M. [Gustavus Adolphus College (United States); Jacot-Guillarmod, R. [Universite de Fribourg (Switzerland); Kammel, P. [University of California (United States); Kim, S.K. [Jeonbuk National University (Korea, Republic of); Knowles, P. [Universite de Fribourg (Switzerland); Kunselman, A.R. [University of Wyoming (United States); Maier, M. [University of Victoria (Canada); Markushin, V.E. [Paul Scherrer Institute (Switzerland); Marshall, G.M. [TRIUMF (Canada); Olin, A. [University of Victoria (Canada); Petitjean, C. [Paul Scherrer Institute (Switzerland); Porcelli, T.A. [University of Victoria (Canada); Stolupin, V.A. [Joint Institute for Nuclear Research (Russian Federation); Wozniak, J. [Institute of Physics and Nuclear Techniques (Poland)] (and others)

    1999-06-15

    Our measurement compares the energy dependence of the scattering cross-sections of muonic deuterium and tritium on hydrogen molecules for collisions in the energy range 0.1-45 eV. A time-of-flight method was used to measure the scattering cross-section as a function of the muonic atom beam energy and shows clearly the Ramsauer-Townsend effect. The results are compared with theoretical calculations by using Monte Carlo simulations. The molecular pd{mu} and pt{mu} formation creates background processes. We measure the formation rates in solid hydrogen by detecting the 5.5 MeV (pd{mu}) and 19.8 MeV (pt{mu}) {gamma}-rays emitted during the subsequent nuclear fusion processes.

  16. Propagation-invariant beams with quantum pendulum spectra: from Bessel beams to Gaussian beam-beams.

    Science.gov (United States)

    Dennis, Mark R; Ring, James D

    2013-09-01

    We describe a new class of propagation-invariant light beams with Fourier transform given by an eigenfunction of the quantum mechanical pendulum. These beams, whose spectra (restricted to a circle) are doubly periodic Mathieu functions in azimuth, depend on a field strength parameter. When the parameter is zero, pendulum beams are Bessel beams, and as the parameter approaches infinity, they resemble transversely propagating one-dimensional Gaussian wave packets (Gaussian beam-beams). Pendulum beams are the eigenfunctions of an operator that interpolates between the squared angular momentum operator and the linear momentum operator. The analysis reveals connections with Mathieu beams, and insight into the paraxial approximation.

  17. Negative ion beam programs at JAERI

    Science.gov (United States)

    Ohara, Y.

    1990-08-01

    Three negative ion beam programs for nuclear fusion research are proposed at the Japan Atomic Energy Research Institute (JAERI): a 500 keV, 10 MW deuterium neutral beam injection (NBI) for heating and current drive in the JT-60U tokamak, a 0.5/1 MeV, 50 MW deuterium beam injection for the Fusion Experimental Reactor (FER), and a 2 MeV, 20 mA lithium beam injection for ion temperature measurement in the JT-60U. The 500 keV negative-ion-based NBI system for the JT-60U will be developed in the first step, followed by the development of the reactor relevant 0.5/1 MeV NBI system. This two step development mitigates the risk in developing a MeV class NBI system.

  18. Light assisted collisions with cold metastable neon atoms

    Energy Technology Data Exchange (ETDEWEB)

    Glover, R D; Laban, D E; Sang, R T, E-mail: R.Sang@griffith.edu.a [Centre for Quantum Dynamics, Griffith University, Brisbane, QLD 4111 (Australia)

    2009-11-01

    Control of the combined Penning and associative ionization cross section is demonstrated with cold ({approx}1mK) metastable Ne (3s{sup 3}P{sub 2}) atoms in a magneto-optical trap (MOT). By illuminating the trapped atoms with a near resonant probe laser beam, increased ionization rates are observed at several detunings. The probe beam is swept through a region from +500MHz to -500MHz. The increase in the Penning and associative ionization cross section is observed in both the red and blue regions of the spectrum.

  19. Design of cantilever probes for Atomic Force Microscopy (AFM)

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2000-01-01

    A cantilever beam used in an Atomic Force Microscope is optimized with respect to two different objectives. The first goal is to maximize the first eigenfrequency while keeping the stiffness of the probe constant. The second goal is to maximize the tip angle of the first eigenmode while again kee...... beam finite elements and the optimizations are carried through with either SLP (Sequential Linear Programming) or MMA (Method of Moving Asymptotes) and similar results are obtained....

  20. 3D shaping of electron beams using amplitude masks

    Energy Technology Data Exchange (ETDEWEB)

    Shiloh, Roy, E-mail: royshilo@post.tau.ac.il; Arie, Ady

    2017-06-15

    Highlights: • Electron beams are shaped in 3D with examples of curves and lattices. • Computer generated holograms are manifested as binary amplitude masks. • Applications in electron-optical particle trapping, manipulation, and synthesis. • Electron beam lithography fabrication scheme explained in detail. • Measurement paradigms of 3D shaped beams are discussed. - Abstract: Shaping the electron wavefunction in three dimensions may prove to be an indispensable tool for research involving atomic-sized particle trapping, manipulation, and synthesis. We utilize computer-generated holograms to sculpt electron wavefunctions in a standard transmission electron microscope in 3D, and demonstrate the formation of electron beams exhibiting high intensity along specific trajectories as well as shaping the beam into a 3D lattice of hot-spots. The concepts presented here are similar to those used in light optics for trapping and tweezing of particles, but at atomic scale resolutions.

  1. Field ionization of free helium atoms: Correlation between the kinetic energy of ionized atoms and probability of their field ionization

    Energy Technology Data Exchange (ETDEWEB)

    Piskur, J.; Borg, L. [Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz (Austria); Stupnik, A.; Leisch, M. [Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, 8010 Graz (Austria); Ernst, W.E. [Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz (Austria); Holst, B. [Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz (Austria)], E-mail: bodil@cantab.net

    2008-05-15

    In this paper the correlation between the kinetic energy of helium atoms and the probability of field ionization is investigated by exploiting the narrow velocity distribution of supersonic molecular beams. Field ionization measurements were carried out on supersonic helium beams at 298 K and 95 K corresponding to energies of about 65 meV and 20 meV, respectively, for the individual atoms. The field ionization was performed with a tungsten tip, radius of curvature 12 nm, kept at room temperature. The ionization probability was found to increase by about a factor 10 when the beam was cooled from 298 K to 95 K. The results presented in this paper are of importance for improving the understanding of field ionization and for the development of a new detector for helium and other molecular beams.

  2. Dynamics of trapped atoms around an optical nanofiber probed through polarimetry.

    Science.gov (United States)

    Solano, Pablo; Fatemi, Fredrik K; Orozco, Luis A; Rolston, S L

    2017-06-15

    The evanescent field outside an optical nanofiber (ONF) can create optical traps for neutral atoms. We present a non-destructive method to characterize such trapping potentials. An off-resonance linearly polarized probe beam that propagates through the ONF experiences a slow axis of polarization produced by trapped atoms on opposite sides along the ONF. The transverse atomic motion is imprinted onto the probe polarization through the changing atomic index of refraction. By applying a transient impulse, we measure a time-dependent polarization rotation of the probe beam that provides both a rapid and non-destructive measurement of the optical trapping frequencies.

  3. Dynamics of trapped atoms around an optical nanofiber probed through polarimetry

    Science.gov (United States)

    Solano, Pablo; Fatemi, Fredrik K.; Orozco, Luis A.; Rolston, S. L.

    2017-06-01

    The evanescent field outside an optical nanofiber (ONF) can create optical traps for neutral atoms. We present a non-destructive method to characterize such trapping potentials. An off-resonance linearly polarized probe beam that propagates through the ONF experiences a slow axis of polarization produced by trapped atoms on opposite sides along the ONF. The transverse atomic motion is imprinted onto the probe polarization through the changing atomic index of of refraction. By applying a transient impulse, we measure a time-dependent polarization rotation of the probe beam that provides both a rapid and non-destructive measurement of the optical trapping frequencies.

  4. Dynamics of single Fe atoms in graphene vacancies.

    Science.gov (United States)

    Robertson, Alex W; Montanari, Barbara; He, Kuang; Kim, Judy; Allen, Christopher S; Wu, Yimin A; Olivier, Jaco; Neethling, Jan; Harrison, Nicholas; Kirkland, Angus I; Warner, Jamie H

    2013-04-10

    Focused electron beam irradiation has been used to create mono and divacancies in graphene within a defined area, which then act as trap sites for mobile Fe atoms initially resident on the graphene surface. Aberration-corrected transmission electron microscopy at 80 kV has been used to study the real time dynamics of Fe atoms filling the vacancy sites in graphene with atomic resolution. We find that the incorporation of a dopant atom results in pronounced displacements of the surrounding carbon atoms of up to 0.5 Å, which is in good agreement with density functional theory calculations. Once incorporated into the graphene lattice, Fe atoms can transition to adjacent lattice positions and reversibly switch their bonding between four and three nearest neighbors. The C atoms adjacent to the Fe atoms are found to be more susceptible to Stone-Wales type bond rotations with these bond rotations associated with changes in the dopant bonding configuration. These results demonstrate the use of controlled electron beam irradiation to incorporate dopants into the graphene lattice with nanoscale spatial control.

  5. Direct detection of antihydrogen atoms using a BGO crystal

    Energy Technology Data Exchange (ETDEWEB)

    Nagata, Y. [Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, 184-8588 Tokyo (Japan); Atomic Physics Research Unit, RIKEN, 2-1 Hirosawa, Wako-shi, 351-0198 Saitama (Japan); Kuroda, N., E-mail: kuroda@phys.c.u-tokyo.ac.jp [Institute of Physics, University of Tokyo, 3-8-1 Komaba, Meguro-ku, 153-8902 Tokyo (Japan); Atomic Physics Research Unit, RIKEN, 2-1 Hirosawa, Wako-shi, 351-0198 Saitama (Japan); Ohtsuka, M. [Institute of Physics, University of Tokyo, 3-8-1 Komaba, Meguro-ku, 153-8902 Tokyo (Japan); Leali, M.; Lodi-Rizzini, E.; Mascagna, V. [Dipartimento di Ingegneria dell' Informazione, Universitá di Brescia, Brescia 25133 (Italy); Istituto Nazionale di Fisica Nucleare, Gruppo Collegato di Brescia, Brescia 25133 (Italy); Tajima, M.; Torii, H.A. [Institute of Physics, University of Tokyo, 3-8-1 Komaba, Meguro-ku, 153-8902 Tokyo (Japan); Atomic Physics Research Unit, RIKEN, 2-1 Hirosawa, Wako-shi, 351-0198 Saitama (Japan); Zurlo, N. [Dipartimento di Ingegneria dell' Informazione, Universitá di Brescia, Brescia 25133 (Italy); Istituto Nazionale di Fisica Nucleare, Gruppo Collegato di Brescia, Brescia 25133 (Italy); Matsuda, Y. [Institute of Physics, University of Tokyo, 3-8-1 Komaba, Meguro-ku, 153-8902 Tokyo (Japan); Atomic Physics Research Unit, RIKEN, 2-1 Hirosawa, Wako-shi, 351-0198 Saitama (Japan); Venturelli, L. [Dipartimento di Ingegneria dell' Informazione, Universitá di Brescia, Brescia 25133 (Italy); Istituto Nazionale di Fisica Nucleare, Gruppo Collegato di Brescia, Brescia 25133 (Italy); Yamazaki, Y. [Atomic Physics Research Unit, RIKEN, 2-1 Hirosawa, Wako-shi, 351-0198 Saitama (Japan)

    2016-12-21

    The ASACUSA collaboration has developed a detector consisting of a large size BGO crystal to detect an atomic antihydrogen beam, and performed the direct detection of antihydrogen atoms. Energy spectra from antihydrogen annihilation on the BGO crystal are discussed in comparison to simulation results from the GEANT4 toolkit. Background mainly originating from cosmic rays were strongly suppressed by analyzing the energy deposited in the BGO and requiring a multiplicity of charged pions. Thus antihydrogen events were identified.

  6. Schlieren imaging of nano-scale atom-surface inelastic transition using a Fresnel biprism atom interferometer

    Science.gov (United States)

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

    2008-05-01

    Surface-induced exo-energetic inelastic transitions among atomic Zeeman states in a magnetic field (“van der Waals Zeeman” transitions) are useable as tuneable beam splitters. A transversally coherent atom beam impinging a pair of opposite surfaces (e.g. 2 edges of a slit or of an ensemble of periodic slits) gives rise to two coherently diffracted wave packets. Within the wave packet overlap, non-localised interference fringes of the Young-slit type are predicted. From the diffraction pattern observed in the Fraunhofer regime (Schlieren image), detailed information about the transition amplitude on a scale of a few nanometers should be derived.

  7. Laser and Electron Beam Processing of Semiconductors: CW Beam Processing of Ion Implanted Silicon

    Science.gov (United States)

    1980-12-31

    1000 A) amorphous layers. Both a scanned cw atoms placed on subsitutional lattice sites for a given anneal argon laser 3 and a scanned e-beam 4...dependence ofthe product v, Nc in the prefactor densities decrease monotonically with distance from the sili- of e., ln(e.IT 2) is plotted versus 1/kT

  8. Slowing dynamics of a supersonic beam, simulation and experiments

    Science.gov (United States)

    Hamamda, Mehdi; Taillandier-Loize, Thierry; Baudon, Jacques; Dutier, Gabriel; Perales, Francisco; Ducloy, Martial

    2015-08-01

    In this paper we present numerical and experimental methods aimed to study the evolution in space and time of a slowed supersonic beam. These generic methods are applicable to a variety of beams and decelerating techniques. The present implemented experimental set up is based upon Zeeman slowing of a metastable atom beam. The detection uses a channel-electron multiplier and a delay-line detector allowing time-of-flight analysis and numerical image reconstruction. In particular a depopulation effect at the centre of the beam is evidenced. In view of quantifying the slowing process, Monte Carlo calculations based on rate-equations are detailed.

  9. Spacecraft charging during ion beam emissions in sunlight

    Science.gov (United States)

    Lai, S. T.; Mcneil, W. J.; Aggson, T. L.

    1990-01-01

    During ion beam emissions from the SCATHA satellite, the potential of the negatively charged satellite body shows a sinusoidal oscillation frequency of once-per-spin of the satellite. The minimum occurs when the ion beam is sunward. The processes that may be responsible for the voltage modulation are considered. Neutralization of ion beam space charge by photoelectrons is examined. The photoelectrons are accelerated by the negative potential of the satellite. Effects of electron impact ionization, excitation of metastable states, and photoionization of xenon neutral atoms in the ion beam are studied in detail. Critical ionization velocity interaction is unlikely under the condition considered.

  10. Long range intermolecular forces in triatomic systems: connecting the atom-diatom and atom-atom-atom representations

    OpenAIRE

    Cvitas, Marko T.; Soldan, Pavel; Hutson, Jeremy M.

    2005-01-01

    The long-range forces that act between three atoms are analysed in both atom-diatom and atom-atom-atom representations. Expressions for atom-diatom dispersion coefficients are obtained in terms of 3-body nonadditive coefficients. The anisotropy of atom-diatom C_6 dispersion coefficients arises primarily from nonadditive triple-dipole and quadruple-dipole forces, while pairwise-additive forces and nonadditive triple-dipole and dipole-dipole-quadrupole forces contribute significantly to atom-di...

  11. Literature in Focus Beta Beams: Neutrino Beams

    CERN Multimedia

    2009-01-01

    By Mats Lindroos (CERN) and Mauro Mezzetto (INFN Padova, Italy) Imperial Press, 2009 The beta-beam concept for the generation of electron neutrino beams was first proposed by Piero Zucchelli in 2002. The idea created quite a stir, challenging the idea that intense neutrino beams only could be produced from the decay of pions or muons in classical neutrino beams facilities or in future neutrino factories. The concept initially struggled to make an impact but the hard work by many machine physicists, phenomenologists and theoreticians over the last five years has won the beta-beam a well-earned position as one of the frontrunners for a possible future world laboratory for high intensity neutrino oscillation physics. This is the first complete monograph on the beta-beam concept. The book describes both technical aspects and experimental aspects of the beta-beam, providing students and scientists with an insight into the possibilities o...

  12. Beam Techniques - Beam Control and Manipulation

    Energy Technology Data Exchange (ETDEWEB)

    Minty, Michiko G

    2003-04-24

    We describe commonly used strategies for the control of charged particle beams and the manipulation of their properties. Emphasis is placed on relativistic beams in linear accelerators and storage rings. After a brief review of linear optics, we discuss basic and advanced beam control techniques, such as transverse and longitudinal lattice diagnostics, matching, orbit correction and steering, beam-based alignment, and linac emittance preservation. A variety of methods for the manipulation of particle beam properties are also presented, for instance, bunch length and energy compression, bunch rotation, changes to the damping partition number, and beam collimation. The different procedures are illustrated by examples from various accelerators. Special topics include injection and extraction methods, beam cooling, spin transport and polarization.

  13. Electron beam control for barely separated beams

    Science.gov (United States)

    Douglas, David R.; Ament, Lucas J. P.

    2017-04-18

    A method for achieving independent control of multiple beams in close proximity to one another, such as in a multi-pass accelerator where coaxial beams are at different energies, but moving on a common axis, and need to be split into spatially separated beams for efficient recirculation transport. The method for independent control includes placing a magnet arrangement in the path of the barely separated beams with the magnet arrangement including at least two multipole magnets spaced closely together and having a multipole distribution including at least one odd multipole and one even multipole. The magnetic fields are then tuned to cancel out for a first of the barely separated beams to allow independent control of the second beam with common magnets. The magnetic fields may be tuned to cancel out either the dipole component or tuned to cancel out the quadrupole component in order to independently control the separate beams.

  14. Atom optics with Rydberg states in inhomogeneous electric fields

    Science.gov (United States)

    Kritsun, Oleg Anton

    Atom optics has become subject of intense investigation in recent years. Control of atomic motion is of great importance in atomic physics and applications like lithography or nanofabrication. Neutral atoms are not affected greatly by magnetic or electric field as they don't have a charge or large magnetic and electric moments. But by exciting a neutral atom to a high Rydberg state it is possible to increase its electric moment considerably. The purpose of this thesis is to demonstrate experimentally and theoretically the possibility of creating atom optical elements for the beam of neutral atoms based on the polarizability of highly excited states in an electric field. First this work will present a review of the basic concepts that are used for atom optics and also a discussion of the progress to date in realizations of the neutral atom manipulation techniques. In our earlier experiments deflection and beam-splitting was demonstrated for a beam of neutral Lithium atoms excited in a three-step scheme [3.5, 3.6]. In later experiments, metastable Helium was excited from 23S state to the 33P state using lambda = 389 nm light, and then to the 25--30 S or D states using lambda = 785--815 nm light. Because this was a two-step excitation and it had the higher laser power in the last step, this method increased the percentage of excited atoms by a factor close to 103 compared to the Lithium experiment. Furthermore coherent excitation technique, Stimulated Raman Adiabatic Population Transfer (STIRAP), is investigated in this system, which allows a complete transfer of the atoms from 23S to the Rydberg states. STIRAP is also very tolerant of experimental imperfections such as intensity and frequency fluctuations, Doppler shifts, etc. and can be done with modest laser power. Efficient excitation enables us to do the following atom manipulations in inhomogeneous electric field [3.6, 4.42]. (1) Deflection and reflection; (2) Beam-splitting; (3) Collimation and focusing. Since

  15. Spooky Phenomena in Two-Photon Coherent Atomic Absorption

    Science.gov (United States)

    Li, Ming-Chiang

    2006-03-01

    Physical processes on two-photon coherent atomic absorption of multiple laser beams were discussed more than twenty five years ago. These processes can be divided into two distinct groups. In the first group, laser beams are from a single source^1,2, and in the second group laser beams are from two different sources^3. Several experiments in the first group were carried out and have led to the 2005 Nobel Prize in physics. The second group is more interesting. Atoms are in random motion and two photons are from different sources. Classically, it is impossible for atoms to transit coherently in the absorption process, but quantum mechanically, such a transition is possible and that is one of the spooky phenomena in quantum mechanic. To assure the coherent transition, each photon as absorbed by the atom must have two possible paths of choices. If one photon has the choice and other one is not, then the atomic transitions cannot be coherent. The present talk will review various spooky phenomena associated with two-photon coherent atomic absorption, and will clarify some theoretical misunderstandings regarding these interesting transitions. Reference: *M. C. Li, Nuovo Cimento 39B (1977) 165. *M. C. Li, Phys. Rev. A 16 (1977) 2480. *M. C. Li, Phys. Rev. A 22 (1980) 1323.

  16. Directly measuring the concurrence of two-atom state via detecting coherent lights

    Science.gov (United States)

    Chen, Li; Yang, Ming; Zhang, Li-Hua; Cao, Zhuo-Liang

    2017-11-01

    Concurrence is an important parameter for quantifying quantum entanglement, but usually the state tomography must be determined before quantification. In this paper we propose a scheme, based on cavity-assisted atom–light interaction, to measure the concurrence of two-atom pure states and the Collins–Gisin state directly, without tomography. The concurrence of atomic states is encoded in the output coherent optical beams after interacting with cavities and the atoms therein, so the results of detection applied to the output coherent optical beams provide the concurrence data of the atomic states. This scheme provides an alternative method for directly measuring atomic entanglement by detecting coherent light, rather than measuring the atomic systems, which thus greatly simplifies the realization complexity of the direct measurement of atomic entanglement. In addition, as the cavity-assisted atom–light interaction used here is robust and scalable in realistic applications, the current scheme may be realized in the near future.

  17. Delivering the world's most intense muon beam

    Science.gov (United States)

    Cook, S.; D'Arcy, R.; Edmonds, A.; Fukuda, M.; Hatanaka, K.; Hino, Y.; Kuno, Y.; Lancaster, M.; Mori, Y.; Ogitsu, T.; Sakamoto, H.; Sato, A.; Tran, N. H.; Truong, N. M.; Wing, M.; Yamamoto, A.; Yoshida, M.

    2017-03-01

    A new muon beam line, the muon science innovative channel, was set up at the Research Center for Nuclear Physics, Osaka University, in Osaka, Japan, using the 392 MeV proton beam impinging on a target. The production of an intense muon beam relies on the efficient capture of pions, which subsequently decay to muons, using a novel superconducting solenoid magnet system. After the pion-capture solenoid, the first 36° of the curved muon transport line was commissioned and the muon flux was measured. In order to detect muons, a target of either copper or magnesium was placed to stop muons at the end of the muon beam line. Two stations of plastic scintillators located upstream and downstream from the muon target were used to reconstruct the decay spectrum of muons. In a complementary method to detect negatively charged muons, the x-ray spectrum yielded by muonic atoms in the target was measured in a germanium detector. Measurements, at a proton beam current of 6 pA, yielded (10.4 ±2.7 )×1 05 muons per watt of proton beam power (μ+ and μ-), far in excess of other facilities. At full beam power (400 W), this implies a rate of muons of (4.2 ±1.1 )×1 08 muons s-1 , among the highest in the world. The number of μ- measured was about a factor of 10 lower, again by far the most efficient muon beam produced. The setup is a prototype for future experiments requiring a high-intensity muon beam, such as a muon collider or neutrino factory, or the search for rare muon decays which would be a signature for phenomena beyond the Standard Model of particle physics. Such a muon beam can also be used in other branches of physics, nuclear and condensed matter, as well as other areas of scientific research.

  18. Single atom microscopy.

    Science.gov (United States)

    Zhou, Wu; Oxley, Mark P; Lupini, Andrew R; Krivanek, Ondrej L; Pennycook, Stephen J; Idrobo, Juan-Carlos

    2012-12-01

    We show that aberration-corrected scanning transmission electron microscopy operating at low accelerating voltages is able to analyze, simultaneously and with single atom resolution and sensitivity, the local atomic configuration, chemical identities, and optical response at point defect sites in monolayer graphene. Sequential fast-scan annular dark-field (ADF) imaging provides direct visualization of point defect diffusion within the graphene lattice, with all atoms clearly resolved and identified via quantitative image analysis. Summing multiple ADF frames of stationary defects produce images with minimized statistical noise and reduced distortions of atomic positions. Electron energy-loss spectrum imaging of single atoms allows the delocalization of inelastic scattering to be quantified, and full quantum mechanical calculations are able to describe the delocalization effect with good accuracy. These capabilities open new opportunities to probe the defect structure, defect dynamics, and local optical properties in 2D materials with single atom sensitivity.

  19. Telecommunication using muon beams

    Science.gov (United States)

    Arnold, Richard C.

    1976-01-01

    Telecommunication is effected by generating a beam of mu mesons or muons, varying a property of the beam at a modulating rate to generate a modulated beam of muons, and detecting the information in the modulated beam at a remote location.

  20. Nonparaxial abruptly autofocusing beams

    Science.gov (United States)

    Penciu, Raluca-Sorina; Makris, Konstantinos G.; Efremidis, Nikolaos K.

    2016-03-01

    We study nonparaxial autofocusing beams with pre-engineered trajectories. We consider the case of linearly polarized electric optical beams and examine their focusing properties such as contrast, beam width, and numerical aperture. Such beams are associated with larger intensity contrasts, can focus at smaller distances, and have smaller spot sizes as compared to the paraxial regime.

  1. ISR beam scrapers

    CERN Multimedia

    CERN PhotoLab

    1972-01-01

    Beam scrapers seen in the direction of the beam. The two horizontal scraper foils are near the centre of the beam pipe andthe two scrapers for protection of the vacuum chamber are further outside. In the lower part of the beam pipe is the vertical halo scraping blade.

  2. Solar Spectroscopy: Atomic Processes

    Science.gov (United States)

    Mason, H.; Murdin, P.

    2000-11-01

    A Greek philosopher called DEMOCRITUS (c. 460-370 BC) first introduced the concept of atoms (which means indivisible). His atoms do not precisely correspond to our atoms of today, which are not indivisible, but made up of a nucleus (protons with positive charge and neutrons which have no charge) and orbiting electrons (with negative charge). Indeed, in the solar atmosphere, the temperature is suc...

  3. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1997-01-01

    This series describes selected advances in the area of atomic spectroscopy. It is primarily intended for the reader who has a background in atmoic spectroscopy; suitable to the novice and expert. Although a widely used and accepted method for metal and non-metal analysis in a variety of complex samples, Advances in Atomic Spectroscopy covers a wide range of materials. Each Chapter will completely cover an area of atomic spectroscopy where rapid development has occurred.

  4. Atomic Lithography: Forcing Epitaxial Growth Using X-Ray Standing Waves

    National Research Council Canada - National Science Library

    Falco, Charles

    1999-01-01

    In a remarkably short time we have made tremendous progress in both the design and construction of a unique "atomic lithography" deposition facility, and in observing effects of an intense x-ray beam...

  5. Atom Interferometer Gyroscope with Spin-Dependent Phase Shifts Induced by Light near a Tune-Out Wavelength

    CERN Document Server

    Trubko, Raisa; Germaine, Michael T St; Gregoire, Maxwell D; Holmgren, William F; Hromada, Ivan; Cronin, Alexander D

    2015-01-01

    Tune-out wavelengths measured with an atom interferometer are sensitive to laboratory rotation rates because of the Sagnac effect, vector polarizability, and dispersion compensation. We observed shifts in measured tune-out wavelengths as large as 213 pm with a potassium atom beam interferometer, and we explore how these shifts can be used for an atom interferometer gyroscope.

  6. BTF measurements with beam-beam interactions

    CERN Document Server

    Gorgen, P.; Fischer, W.

    2014-07-17

    We present considerations about the transverse beam transfer function (BTF) of beams under the influence of two effects: The strong-strong beam-beam effect and the influence of a Gaussian electron lens. The BTF are investigated using two methods: BTF excitation is simulated in a particle-in-cell (PIC) code. The BTF model is verified using a known analytic expectation. Analytic expectations for BTF of beams under a stationary electron lens are derived by extending BTF from the formalism of Berg and Ruggiero. Finally we compare the analytic BTF results for a stationary Gaussian lens to both the PIC simulation for split tune conditions and to PIC simulations for a beam influenced by an electron lens. We conclude that the formalism represents the electron lens well and can be applied to a limited extend to the beam-beam effect under split tune conditions. The analytic formalism allows us to recover the strength of an electron lens by means of fitting and can give clues regarding the strength of the beam-beam effe...

  7. The beam dump tunnels

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    In these images workers are digging the tunnels that will be used to dump the counter-circulating beams. Travelling just a fraction under the speed of light, the beams at the LHC will each carry the energy of an aircraft carrier travelling at 12 knots. In order to dispose of these beams safely, a beam dump is used to extract the beam and diffuse it before it collides with a radiation shielded graphite target.

  8. Trapped Circular Rydberg Atoms for Quantum Simulation

    Science.gov (United States)

    Cantat-Moltrecht, Tigrane; Nguyen, Thanh Long; Cortinas, Rodrigo; Sayrin, Clément; Haroche, Serge; Brune, Michel; Raimond, Jean-Michel

    2017-04-01

    Condensed-matter systems are interesting and important to understand but they are difficult to study, even numerically, given the significant sizes of their Hilbert space. Quantum simulation proposes to mimic those out-of-reach quantum systems with more controllable and accessible ones. The high polarizability of Rydberg atoms allows for strong and tunable short-range interactions, making them nice candidates for a quantum simulation platform. However, low angular momentum Rydberg atoms cannot be efficiently laser-trapped and their lifetimes would limit the scope of such a quantum simulator. We propose instead to use circular Rydberg atoms (of maximum angular momentum) which can be laser-trapped and whose lifetimes can be extended to the one minute range by placing them in a spontaneous emission-inhibiting capacitor. We aim at the deterministic preparation of a 1D-chain of 40 atoms, trapped in a Laguerre-Gauss hollow laser beam, with a collective lifetime of 2 seconds. With exchange rates in the 10 - 100 kHz range, this would provide a platform able to simulate quantum many-body physics for more than 104 exchange times. In this talk I will present this novel quantum simulation platform and our latest experimental results in the laser-trapping of circular Rydberg atoms.

  9. Laser Spectroscopy of Antiprotonic Helium Atoms

    CERN Multimedia

    2002-01-01

    %PS205 %title\\\\ \\\\Following the discovery of metastable antiprotonic helium atoms ($\\overline{p}He^{+} $) at KEK in 1991, systematic studies of their properties were made at LEAR from 1991 to 1996. In the first two years the lifetime of $\\overline{p}He^{+}$ in liquid and gaseous helium at various temperatures and pressures was measured and the effect of foreign gases on the lifetime of these atoms was investigated. Effects were also discovered which gave the antiproton a 14\\% longer lifetime in $^4$He than in $^3$He, and resulted in important differences in the shape of the annihilation time spectra in the two isotopes.\\\\ \\\\Since 1993 laser spectroscopy of the metastable $\\overline{p}He^{+}$ atoms became the main focus of PS205. Transitions were stimulated between metastable and non-metastable states of the $\\overline{p}He^{+}$ atom by firing a pulsed dye laser beam into the helium target every time an identified metastable atom was present (Figure 1). If the laser frequency matched the transition energy, the...

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

    Energy Technology Data Exchange (ETDEWEB)

    Leutenegger, M. A. [NASA Goddard Space Flight Center, Code 662, Greenbelt, Maryland 20771 (United States); CRESST/University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Beiersdorfer, P.; Brown, G. V.; Magee, E. W. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Betancourt-Martinez, G. L. [NASA Goddard Space Flight Center, Code 662, Greenbelt, Maryland 20771 (United States); University of Maryland College Park, College Park, Maryland 20742 (United States); Hell, N. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Dr. Karl-Remeis-Sternwarte and ECAP, FAU Erlangen-Nürnberg, Sternwartstr. 7, 96049 Bamberg (Germany); Kelley, R. L.; Kilbourne, C. A.; Porter, F. S. [NASA Goddard Space Flight Center, Code 662, Greenbelt, Maryland 20771 (United States)

    2016-11-15

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

  11. Measurement of frequency sweep nonlinearity using atomic absorption spectroscopy

    Science.gov (United States)

    Song, Ningfang; Lu, Xiangxiang; Xu, Xiaobin; Pan, Xiong; Li, Wei; Hu, Di; Liu, Jixun

    2018-01-01

    A novel scheme to determine frequency sweep nonlinearity using atomic saturated absorption spectroscopy is proposed and demonstrated. The frequency modulation rate is determined by directly measuring the interference fringe number and the frequency gap between two atomic transition peaks of rubidium atom. An experimental setup is established, and test results show that the frequency sweep nonlinearity is ∼10%, with an average frequency modulation rate of ∼1.12 THz/s. Moreover, the absolute optical frequency and optical path difference between two laser beams are simultaneously determined with this method. This low-cost technique can be used for optical frequency sweep nonlinearity correction and real-time frequency monitor.

  12. Condensed matter applied atomic collision physics, v.4

    CERN Document Server

    Datz, Sheldon

    1983-01-01

    Applied Atomic Collision Physics, Volume 4: Condensed Matter deals with the fundamental knowledge of collision processes in condensed media.The book focuses on the range of applications of atomic collisions in condensed matter, extending from effects on biological systems to the characterization and modification of solids. This volume begins with the description of some aspects of the physics involved in the production of ion beams. The radiation effects in biological and chemical systems, ion scattering and atomic diffraction, x-ray fluorescence analysis, and photoelectron and Auger spectrosc

  13. Spin-to-orbital angular momentum conversion and spin-polarization filtering in electron beams.

    Science.gov (United States)

    Karimi, Ebrahim; Marrucci, Lorenzo; Grillo, Vincenzo; Santamato, Enrico

    2012-01-27

    We propose the design of a space-variant Wien filter for electron beams that induces a spin half-turn and converts the corresponding spin angular momentum variation into orbital angular momentum of the beam itself by exploiting a geometrical phase arising in the spin manipulation. When applied to a spatially coherent input spin-polarized electron beam, such a device can generate an electron vortex beam, carrying orbital angular momentum. When applied to an unpolarized input beam, the proposed device, in combination with a suitable diffraction element, can act as a very effective spin-polarization filter. The same approach can also be applied to neutron or atom beams.

  14. Method and apparatus for reducing coherence of high-power laser beams

    Science.gov (United States)

    Moncur, Norman K.; Mayer, Frederick J.

    1978-01-01

    Method and apparatus for reducing the coherence and for smoothing the power density profile of a collimated high-power laser beam in which the beam is focused at a point on the surface of a target fabricated of material having a low atomic number. The initial portion of the focused beam heats the material to form a hot reflective plasma at the material surface. The remaining, major portion of the focused beam is reflected by the plasma and recollected to form a collimated beam having reduced beam coherence.

  15. Valley-dependent gauge fields for ultracold atoms in square optical superlattices

    Science.gov (United States)

    Zhang, Dan-Wei; Shan, Chuan-Jia; Mei, Feng; Yang, Mou; Wang, Rui-Qiang; Zhu, Shi-Liang

    2014-01-01

    We propose an experimental scheme to realize the valley-dependent gauge fields for ultracold fermionic atoms trapped in a state-dependent square optical lattice. Our scheme relies on two sets of Raman laser beams to engineer the hopping between adjacent sites populated by two-component fermionic atoms. One set of Raman beams is used to realize a staggered π-flux lattice, where low-energy atoms near two inequivalent Dirac points should be described by the Dirac equation for spin-1/2 particles. Another set of laser beams with proper Rabi frequencies is added to further modulate the atomic hopping parameters. The hopping modulation will give rise to effective gauge potentials with opposite signs near the two valleys, mimicking the interesting strain-induced pseudogauge fields in graphene. The proposed valley-dependent gauge fields are tunable and provide an alternative route to realize an uncommon type of quantum Hall effects and atomic devices.

  16. Aberration-corrected STEM for atomic-resolution imaging and analysis.

    Science.gov (United States)

    Krivanek, O L; Lovejoy, T C; Dellby, N

    2015-09-01

    Aberration-corrected scanning transmission electron microscopes are able to form electron beams smaller than 100 pm, which is about half the size of an average atom. Probing materials with such beams leads to atomic-resolution images, electron energy loss and energy-dispersive X-ray spectra obtained from single atomic columns and even single atoms, and atomic-resolution elemental maps. We review briefly how such electron beams came about, and show examples of applications. We also summarize recent developments that are propelling aberration-corrected scanning transmission electron microscopes in new directions, such as complete control of geometric aberration up to fifth order, and ultra-high-energy resolution EELS that is allowing vibrational spectroscopy to be carried out in the electron microscope. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  17. Multi-level cascaded electromagnetically induced transparency in cold atoms using an optical nanofibre interface

    CERN Document Server

    Kumar, Ravi; Chormaic, Síle Nic

    2015-01-01

    Ultrathin optical fibres integrated into cold atom setups are proving to be ideal building blocks for atom-photon hybrid quantum networks. Such optical nanofibres (ONF) can be used for the demonstration of nonlinear optics and quantum interference phenomena in atomic media. Here, we report on the observation of multilevel cascaded electromagnetically induced transparency (EIT) using an optical nanofibre to interface cold $^{87}$Rb atoms through the intense evanescent fields that can be achieved at ultralow probe and coupling powers. Both the probe (at 780 nm) and the coupling (at 776 nm) beams propagate through the nanofibre. The observed multipeak transparency spectra of the probe beam could offer a method for simultaneously slowing down multiple wavelengths in an optical nanofibre or for generating ONF-guided entangled beams, showing the potential of such an atom-nanofibre system for quantum information. We also demonstrate all-optical-switching in the all fibred system using the obtained EIT effect.

  18. Single qubit gates in a 3D array of neutral atoms

    Science.gov (United States)

    Corcovilos, Theodore A.; Wang, Yang; Li, Xiao; Weiss, David S.; Kim, Jungsang

    2012-06-01

    We present an approach to quantum computing using single Cs atoms in a cubic 5-μm spaced 3D optical lattice. After cooling the atoms to near their vibrational ground state (76% ground state occupancy) using projection sideband cooling, we manipulate the state of individual atoms using the AC Stark shift induced by intersecting lasers and microwave pulses that are only resonant with the shifted atom. Here we demonstrate Rabi oscillations of a single atom in the center of the array and progress towards steering the beams to address the other atoms. Rapid steering of the lasers using micromirrors allows single-atom gates of ˜10 μs. This single-site addressing along with lattice polarization rotation will enable us to fill voids in the central region of the atom array by selectively moving individual atoms. Future work will couple adjacent qubits via the Rydberg blockade mechanism with expected two-qubit gate times of ˜100 ns.

  19. THERMO-MECHANICAL MODELLING OF METAL STRUCTURES SUBJECTED TO HIGH ENERGY PARTICLE BEAM IMPACTS

    CERN Document Server

    Peroni, L; Dallocchio, A

    2011-01-01

    Particle accelerators [Wiedemann 1993] act as microscopes for such a complex research; these large machines accelerate charged elementary particles (electrons, protons or ionized atoms) to high kinetic energies. A high energy particle beam can be brought into collision against a fixed target or against another beam and from this encounter a multitude of short life sub-atomic particles is originated. The higher the energy of the colliding beams and the event rate, the wider the spectrum of the generable sub-atomic particles.

  20. Atoms, Molecules, and Compounds

    CERN Document Server

    Manning, Phillip

    2007-01-01

    Explores the atoms that govern chemical processes. This book shows how the interactions between simple substances such as salt and water are crucial to life on Earth and how those interactions are predestined by the atoms that make up the molecules.

  1. Atoms, Molecules and Radiation

    Indian Academy of Sciences (India)

    IAS Admin

    A Refresher Course in Applications of Quantum Mechanics to 'Atoms, Molecules and Radiation' will be held at the Indian Academy of Sciences, Bangalore from December 8 to 20. 2014. The Course is primarily aimed at teachers teaching quantum mechanics and/ or atomic and molecular physics at the UG / PG level.

  2. When Atoms Want

    Science.gov (United States)

    Talanquer, Vicente

    2013-01-01

    Chemistry students and teachers often explain the chemical reactivity of atoms, molecules, and chemical substances in terms of purposes or needs (e.g., atoms want or need to gain, lose, or share electrons in order to become more stable). These teleological explanations seem to have pedagogical value as they help students understand and use…

  3. Atomicity in Electronic Commerce,

    Science.gov (United States)

    1996-01-01

    Atomicity in Electronic Commerce J. D. Tygar January 1996 CMU-CS-96-112 School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213...other research sponsor. Keywords: electronic commerce , atomicity, NetBill, IBIP, cryptography, transaction pro- cessing, ACID, franking, electronic ...goods over networks. Electronic commerce has inspired a large variety of work. Unfortunately, much of that work ignores traditional transaction

  4. Compact atom interferometer using single laser

    Science.gov (United States)

    Chiow, Sheng-Wey; Yu, Nan

    2017-04-01

    Atom interferometer (AI) based sensors exhibit precision and accuracy unattainable with classical sensors, thanks to the inherent stability of atomic properties. The complexity of required laser system and the size of vacuum chamber driven by optical access requirement limit the applicability of such technology in size, weight, and power (SWaP) challenging environments, such as in space. For instance, a typical physics package of AI includes six viewports for laser cooling and trapping, two for AI beams, and two more for detection and a vacuum pump. Similarly, a typical laser system for an AI includes two lasers for cooling and repumping, and two for Raman transitions as AI beam splitters. In this presentation, we report our efforts in developing a miniaturized atomic accelerometer for planetary exploration. We will describe a physics package configuration having minimum optical access (thus small volume), and a laser and optics system utilizing a single laser for the sensor operation. Preliminary results on acceleration sensitivity will be discussed. We will also illustrate a path for further packaging and integration based on the demonstrated concepts. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  5. Beam diagnostics for low energy beams

    Directory of Open Access Journals (Sweden)

    J. Harasimowicz

    2012-12-01

    Full Text Available Low-energetic ion and antimatter beams are very attractive for a number of fundamental studies. The diagnostics of such beams, however, is a challenge due to low currents down to only a few thousands of particles per second and significant fraction of energy loss in matter at keV beam energies. A modular set of particle detectors has been developed to suit the particular beam diagnostic needs of the ultralow-energy storage ring (USR at the future facility for low-energy antiproton and ion research, accommodating very low beam intensities at energies down to 20 keV. The detectors include beam-profile monitors based on scintillating screens and secondary electron emission, sensitive Faraday cups for absolute intensity measurements, and capacitive pickups for beam position monitoring. In this paper, the design of all detectors is presented in detail and results from beam measurements are shown. The resolution limits of all detectors are described and options for further improvement summarized. Whilst initially developed for the USR, the instrumentation described in this paper is also well suited for use in other low-intensity, low-energy accelerators, storage rings, and beam lines.

  6. Theoretical atomic physics

    CERN Document Server

    Friedrich, Harald

    2017-01-01

    This expanded and updated well-established textbook contains an advanced presentation of quantum mechanics adapted to the requirements of modern atomic physics. It includes topics of current interest such as semiclassical theory, chaos, atom optics and Bose-Einstein condensation in atomic gases. In order to facilitate the consolidation of the material covered, various problems are included, together with complete solutions. The emphasis on theory enables the reader to appreciate the fundamental assumptions underlying standard theoretical constructs and to embark on independent research projects. The fourth edition of Theoretical Atomic Physics contains an updated treatment of the sections involving scattering theory and near-threshold phenomena manifest in the behaviour of cold atoms (and molecules). Special attention is given to the quantization of weakly bound states just below the continuum threshold and to low-energy scattering and quantum reflection just above. Particular emphasis is laid on the fundamen...

  7. Atomic diffusion in stars

    CERN Document Server

    Michaud, Georges; Richer, Jacques

    2015-01-01

    This book gives an overview of atomic diffusion, a fundamental physical process, as applied to all types of stars, from the main sequence to neutron stars. The superficial abundances of stars as well as their evolution can be significantly affected. The authors show where atomic diffusion plays an essential role and how it can be implemented in modelling.  In Part I, the authors describe the tools that are required to include atomic diffusion in models of stellar interiors and atmospheres. An important role is played by the gradient of partial radiative pressure, or radiative acceleration, which is usually neglected in stellar evolution. In Part II, the authors systematically review the contribution of atomic diffusion to each evolutionary step. The dominant effects of atomic diffusion are accompanied by more subtle effects on a large number of structural properties throughout evolution. One of the goals of this book is to provide the means for the astrophysicist or graduate student to evaluate the importanc...

  8. Maximally Atomic Languages

    Directory of Open Access Journals (Sweden)

    Janusz Brzozowski

    2014-05-01

    Full Text Available The atoms of a regular language are non-empty intersections of complemented and uncomplemented quotients of the language. Tight upper bounds on the number of atoms of a language and on the quotient complexities of atoms are known. We introduce a new class of regular languages, called the maximally atomic languages, consisting of all languages meeting these bounds. We prove the following result: If L is a regular language of quotient complexity n and G is the subgroup of permutations in the transition semigroup T of the minimal DFA of L, then L is maximally atomic if and only if G is transitive on k-subsets of 1,...,n for 0 <= k <= n and T contains a transformation of rank n-1.

  9. Light-shift measurement and suppression in atomic spin gyroscope.

    Science.gov (United States)

    Fang, Jiancheng; Wan, Shuangai; Chen, Yao; Li, Rujie

    2012-11-01

    We present a method to determine and suppress the light shift in an atomic spin gyroscope. This method doesn't require additional drive source or frequency modulation, and it is based on the dynamics of an atomic spin gyroscope to determine a clean curve as a function of the frequency of the pump beam that predicts the zero light shift. We experimentally validate the method in a Cs-(129)Xe atomic spin gyroscope and verify the results through numerical simulations. This method can also be applied to an atomic spin magnetometer based on the spin-exchange relaxation-free exchange that experiences light shift. The method is useful for atomic spin devices because it can improve long-term performance and reduce the influence of the laser.

  10. Trapping of molecular Oxygen together with Lithium atoms

    CERN Document Server

    Akerman, Nitzan; Segev, Yair; Bibelnik, Natan; Narevicius, Julia; Narevicius, Edvardas

    2016-01-01

    We demonstrate simultaneous deceleration and trapping of a cold atomic and molecular mixture. This is the first step towards studies of cold atom-molecule collisions at low temperatures as well as application of sympathetic cooling. Both atoms and molecules are cooled in a supersonic expansion and are loaded into a moving magnetic trap which brings them to rest via the Zeeman interaction from an initial velocity of 375 m/s. We use a beam seeded with molecular Oxygen, and entrain it with Lithium atoms by laser ablation prior to deceleration. The deceleration ends with loading of the mixture into a static quadrupole trap, which is generated by two permanent magnets. We estimate $10^9$ trapped O$_2$ molecules and $10^5$ Li atoms with background pressure limited lifetime on the order of 1 second. With further improvements to Lithium entrainment we expect that sympathetic cooling of molecules is within reach.

  11. Simulated mixed absorbers and effective atomic numbers for γ ...

    Indian Academy of Sciences (India)

    The total -ray interaction crosss-sections on mixed absorbers were determined at 662 keV with a view to study the effective atomic numbers for -ray absorption under narrow beam good geometry set-up. The measurements were taken for the combination of metallic absorbers like aluminium, copper, lead and mercury ...

  12. Precision spectroscopy on atomic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Parthey, Christian Godehard

    2011-12-15

    This Thesis reports on three measurements involving the 1S-2S transition in atomic hydrogen and deuterium conducted on a 5.8 K atomic beam. The transition is excited Doppler-free via two counter-propagating photons near 243 nm. The H/D isotope shift has been determined as {delta}{integral}{sub exp}=670 994 334 606(15) Hz. Comparing with the theoretical value for the isotope shift, excluding the leading nuclear size effect, {delta}{integral}{sub th}=670 999 566.90(66)(60) kHz we confirm, twice more accurate, the rms charge radius difference of the deuteron and the proton as left angle r{sup 2} right angle {sub d}- left angle r{sup 2} right angle {sub p}=3.82007(65) fm{sup 2} and the deuteron structure radius r{sub str}=1.97507(78) fm. The frequency ratio of the 1S-2S transition in atomic hydrogen to the cesium ground state hyperfine transition provided by the mobile cesium fountain clock FOM is measured to be {integral}{sub 1S-2S}=2 466 061 413 187 035 (10) Hz which presents a fractional frequency uncertainty of 4.2 x 10{sup -15}. The second absolute frequency measurement of the 1S-2S transition in atomic hydrogen presents the first application of a 900 km fiber link between MPQ and Physikalisch- Technische Bundesanstalt (PTB) in Braunschweig which we have used to calibrate the MPQ hydrogen maser with the stationary cesium fountain clock CSF1 at PTB. With the result of {integral}{sub 1S-2S}=2 466 061 413 187 017 (11) Hz we can put a constraint on the electron Lorentz boost violating coefficients 0.95c{sub (TX)}-0.29c{sub (TY)}-0.08 c{sub (TZ)}=(2.2{+-}1.8) x 10{sup -11} within the framework of minimal standard model extensions. We limit a possible drift of the strong coupling constant through the ratio of magnetic moments at a competitive level ({partial_derivative})/({partial_derivative}t)ln ({mu}{sub Cs})/({mu}{sub B})=-(3.0{+-}1.2) x 10{sup -15} yr{sup -1}.

  13. Molecular beam simulation of planetary atmospheric entry - Some recent results.

    Science.gov (United States)

    French, J. B.; Reid, N. M.; Nier, A. O.; Hayden, J. L.

    1972-01-01

    Progress is reported in the development of molecular beam techniques to simulate entry into planetary atmospheres. Molecular beam sources for producing fast beams containing CO2 and atomic oxygen are discussed. Results pertinent to the design and calibration of a mass spectrometer ion source for measurement of the Martian atmosphere during the free molecule portion of the entry trajectory are also presented. The shortcomings and advantages of this simulation technique are discussed, and it is demonstrated that even with certain inadequacies much information useful to the ion source design was obtained. Particularly, it is shown that an open-cavity configuration retains sensitivity to atomic oxygen, provides reasonable signal enhancement from the stagnation effect, is not highly sensitive to pitch and yaw effects, and presents no unforeseen problems in measuring CO2 or atomic oxygen.

  14. Low current beam techniques

    Energy Technology Data Exchange (ETDEWEB)

    Saint, A.; Laird, J.S.; Bardos, R.A.; Legge, G.J.F. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Nishijima, T.; Sekiguchi, H. [Electrotechnical Laboratory, Tsukuba (Japan).

    1993-12-31

    Since the development of Scanning Transmission Microscopy (STIM) imaging in 1983 many low current beam techniques have been developed for the scanning (ion) microprobe. These include STIM tomography, Ion Beam Induced Current, Ion Beam Micromachining and Microlithography and Ionoluminense. Most of these techniques utilise beam currents of 10{sup -15} A down to single ions controlled by beam switching techniques This paper will discuss some of the low beam current techniques mentioned above, and indicate, some of their recent applications at MARC. A new STIM technique will be introduced that can be used to obtain Z-contrast with STIM resolution. 4 refs., 3 figs.

  15. Ultimate Statistical Physics: fluorescence of a single atom

    CERN Document Server

    Pomeau, Yves; Ginibre, Jean

    2016-01-01

    We discuss the statistics of emission of photons by a single atom or ion illuminated by a laser beam at the frequency of quasi-resonance between two energy levels, a situation that corresponds to real experiments. We extend this to the case of two laser beams resonant with the energy differences between two excited levels and the ground state (three level atom in V-configuration). We use a novel approach of this type of problem by considering Kolmogorov equation for the probability distribution of the atomic state which takes into account first the deterministic evolution of this state under the effect of the incoming laser beam and the random emission of photons during the spontaneous decay of the excited state(s) to the ground state. This approach yields solvable equations in the two level atom case. For the three level atom case we set the problem and define clearly its frame. The results obtained are valid both in the opposite limits of rare and of frequent spontaneous decay, compared to the period of the...

  16. Laboratory investigations involving high-velocity oxygen atoms

    Science.gov (United States)

    Leger, Lubert J.; Koontz, Steven L.; Visentine, James T.; Cross, Jon B.

    1989-01-01

    Facilities for measuring material reactive characteristics have been under development for several years and span the atom energy range from thermal to 5 eV, the orbital collision energy. One of the high-atom energy facilities (The High Intensity/Energy Atomic Oxygen Source) capable of simulating the reactive part of LEO is described, along with results of beam characterization and preliminary material studies. The oxygen atom beam source was a continuous wave plasma produced by focusing a high-power CO2 laser through a lens system into a rare gas/molecular oxygen mixture chamber at elevated temperature. Material samples were exposed to the high velocity beam through an external feedthrough. The facility showed good stability in continued operation for more than 100 hours, producing fluences of 10 to the 21st to 10 to the 22nd atoms/sq cm. Reaction efficiencies and surface morphology have been measured for several materials at energies of 1.5 and 2.8 eV, matching with data generated from previous space flights. Activation energies for carbon and Kapton as measured in this facility were 800 cal/mole.

  17. Beam-smoothing investigation on Heaven I

    Science.gov (United States)

    Xiang, Yi-huai; Gao, Zhi-xing; Tong, Xiao-hui; Dai, Hui; Tang, Xiu-zhang; Shan, Yu-sheng

    2007-01-01

    Directly driven targets for inertial confinement fusion (ICF) require laser beams with extremely smooth irradiance profiles to prevent hydrodynamic instabilities that destroy the spherical symmetry of the target during implosion. Such instabilities can break up and mix together the target's wall and fuel material, preventing it from reaching the density and temperature required for fusion ignition. 1,2 Measurements in the equation of state (EOS) experiments require laser beams with flat-roofed profiles to generate uniform shockwave 3. Some method for beam smooth, is thus needed. A technique called echelon-free induced spatial incoherence (EFISI) is proposed for producing smooth target beam profiles with large KrF lasers. The idea is basically an image projection technique that projects the desired time-averaged spatial profile onto the target via the laser system, using partially coherent broadband lighe. Utilize the technique, we developing beam- smoothing investigation on "Heaven I". At China Institute of Atomic Energy , a new angular multiplexing providing with beam-smoothing function has been developed, the total energy is 158J, the stability of energy is 4%, the pulse duration is 25ns, the effective diameter of focusing spot is 400um, and the ununiformity is about 1.6%, the power density on the target is about 3.7×10 12W/cm2. At present, the system have provided steady and smooth laser irradiation for EOS experiments.

  18. PHARAO space atomic clock: new developments on the laser source

    Science.gov (United States)

    Saccoccio, Muriel; Loesel, Jacques; Coatantiec, Claude; Simon, Eric; Laurent, Philippe; Lemonde, Pierre; Maksimovic, I.; Abgrall, M.

    2017-11-01

    The PHARAO project purpose is to open the way for a new atomic clock generation in space, where laser cooling techniques and microgravity allow high frequency stability and accuracy. The French space agency, CNES is funding and managing the clock construction. The French SYRTE and LKB laboratories are scientific and technical advisers for the clock requirements and the follow-up of subsystem development in industrial companies. EADS SODERN is developing two main subsystems of the PHARAO clock: the Laser Source and the Cesium Tube where atoms are cooled, launched, selected and detected by laser beams. The Laser Source includes an optical bench and electronic devices to generate the laser beams required. This paper describes PHARAO and the role laser beams play in its principle of operation. Then we present the Laser Source design, the technologies involved, and the status of development. Lastly, we focus of a key equipment to reach the performances expected, which is the Extended Cavity Laser Diode.

  19. Strategies for mitigating the ionization-induced beam head erosion problem in an electron-beam-driven plasma wakefield accelerator

    Directory of Open Access Journals (Sweden)

    W. An

    2013-10-01

    Full Text Available Strategies for mitigating ionization-induced beam head erosion in an electron-beam-driven plasma wakefield accelerator (PWFA are explored when the plasma and the wake are both formed by the transverse electric field of the beam itself. Beam head erosion can occur in a preformed plasma because of a lack of focusing force from the wake at the rising edge (head of the beam due to the finite inertia of the electrons. When the plasma is produced by field ionization from the space charge field of the beam, the head erosion is significantly exacerbated due to the gradual recession (in the beam frame of the 100% ionization contour. Beam particles in front of the ionization front cannot be focused (guided causing them to expand as in vacuum. When they expand, the location of the ionization front recedes such that even more beam particles are completely unguided. Eventually this process terminates the wake formation prematurely, i.e., well before the beam is depleted of its energy. Ionization-induced head erosion can be mitigated by controlling the beam parameters (emittance, charge, and energy and/or the plasma conditions. In this paper we explore how the latter can be optimized so as to extend the beam propagation distance and thereby increase the energy gain. In particular we show that, by using a combination of the alkali atoms of the lowest practical ionization potential (Cs for plasma formation and a precursor laser pulse to generate a narrow plasma filament in front of the beam, the head erosion rate can be dramatically reduced. Simulation results show that in the upcoming “two-bunch PWFA experiments” on the FACET facility at SLAC national accelerator laboratory the energy gain of the trailing beam can be up to 10 times larger for the given parameters when employing these techniques. Comparison of the effect of beam head erosion in preformed and ionization produced plasmas is also presented.

  20. Electron beam welding and beam positioning

    OpenAIRE

    MOROZOV M.Y.; BRAVERMAN V.Y.; MEDNIKOV D.M.

    2015-01-01

    Programs for control of mutual movements of the welded parts and EB gun are written in the unified language ISO-7bit. Beam settings control uses electronic charts or optional languages, sometimes self-designed. Operator coordinates movements and beam settings manually.

  1. T10 Beam Studies & Beam Simulation

    CERN Document Server

    Bergmann, Michael Georges; Van Dijk, Maarten; CERN. Geneva. EN Department

    2017-01-01

    In order to test detector components before their installation in actual experiments, one uses test beams in which one can control particle typ, momentum and size to high degree. For this project the focus of a secondary beam at T10 in the East Area at CERN was analysed using an AZALEA telescope from DESY.

  2. Beam Dynamics and Beam Losses - Circular Machines

    CERN Document Server

    Kain, V

    2016-01-01

    A basic introduction to transverse and longitudinal beam dynamics as well as the most relevant beam loss mechanisms in circular machines will be presented in this lecture. This lecture is intended for physicists and engineers with little or no knowledge of this subject.

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

    Science.gov (United States)

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

    2015-07-24

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

  4. Optical dipole mirror for cold atoms based on a metallic diffraction grating

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Bartoszek-Bober, Dobroslawa; Panas, Roman

    We report on the realization of a plasmonic dipole mirror for cold atoms based on a metallic grating coupler. A cloud of atoms is reflected by the repulsive potential generated by surface plasmon polaritons (SPPs) excited on a reflection gold grating by a 780 nm laser beam. Experimentally...... and numerically determined mirror efficiencies are close to 100%. The intensity of SPPs above a real grating coupler and the atomic trajectories, as well as the momentum dispersion of the atom cloud being reflected, are computed. A suggestion is given as to how the plasmonic mirror might serve as an optical atom...

  5. Optical dipole mirror for cold atoms based on a metallic diffraction grating

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Bartoszek-Bober, Dobroslawa; Panas, Roman

    2014-01-01

    We report on the realization of a plasmonic dipole mirror for cold atoms based on a metallic grating coupler. A cloud of atoms is reflected by the repulsive potential generated by surface plasmon polaritons (SPPs) excited on a reflection gold grating by a 780 nm laser beam. Experimentally...... and numerically determined mirror efficiencies are close to 100%. The intensity of SPPs above a real grating coupler and the atomic trajectories, as well as the momentum dispersion of the atom cloud being reflected, are computed. A suggestion is given as to how the plasmonic mirror might serve as an optical atom...

  6. Structural examination of lithium niobate ferroelectric crystals by combining scanning electron microscopy and atomic force microscopy

    Science.gov (United States)

    Efremova, P. V.; Ped'ko, B. B.; Kuznecova, Yu. V.

    2016-02-01

    The structure of lithium niobate single crystals is studied by a complex technique that combines scanning electron microscopy and atomic force microscopy. By implementing the piezoresponse force method on an atomic force microscope, the domain structure of lithium niobate crystals, which was not revealed without electron beam irradiation, is visualized

  7. Nanolithography with metastable helium atoms in a high-power standing-wave light field

    NARCIS (Netherlands)

    Petra, S.J.H.; Feenstra, L.; Hogervorst, W.; Vassen, W.

    2004-01-01

    We have created periodic nanoscale structures in a gold substrate with a lithography process using metastable triplet helium atoms that damage a hydrophobic resist layer on top of the substrate. A beam of metastable helium atoms is transversely collimated and guided through an intense standing-wave

  8. Status and perspectives of atomic physics research at GSI : The new GSI accelerator project

    NARCIS (Netherlands)

    Stolker, T; Backe, H; Beyer, HF; Brauning-Demian, A; Hagmann, S; Ionescu, DC; Jungmann, K; Kluge, HJ; Kozhuharov, C; Kuhl, T; Liesen, D; Mann, R; Mokler, PH; Quint, W; Bosch, F.M.

    A short overview on the results of atomic physics research at the storage ring ESR is given followed by a presentation of the envisioned atomic physics program at the planned new GSI facility. The proposed new GSI facility will provide highest intensities of relativistic beams of both stable and

  9. Successful Beam-Beam Tuneshift Compensation

    Energy Technology Data Exchange (ETDEWEB)

    Bishofberger, Kip Aaron [Univ. of California, Los Angeles, CA (United States)

    2005-01-01

    The performance of synchrotron colliders has been limited by the beam-beam limit, a maximum tuneshift that colliding bunches could sustain. Due to bunch-to-bunch tune variation and intra-bunch tune spread, larger tuneshifts produce severe emittance growth. Breaking through this constraint has been viewed as impossible for several decades. This dissertation introduces the physics of ultra-relativistic synchrotrons and low-energy electron beams, with emphasis placed on the limits of the Tevatron and the needs of a tuneshift-compensation device. A detailed analysis of the Tevatron Electron Lens (TEL) is given, comparing theoretical models to experimental data whenever possible. Finally, results of Tevatron operations with inclusion of the TEL are presented and analyzed. It is shown that the TEL provides a way to shatter the previously inescapable beam-beam limit.

  10. Single-atom nanoelectronics

    CERN Document Server

    Prati, Enrico

    2013-01-01

    Single-Atom Nanoelectronics covers the fabrication of single-atom devices and related technology, as well as the relevant electronic equipment and the intriguing new phenomena related to single-atom and single-electron effects in quantum devices. It also covers the alternative approaches related to both silicon- and carbon-based technologies, also from the point of view of large-scale industrial production. The publication provides a comprehensive picture of the state of the art at the cutting edge and constitutes a milestone in the emerging field of beyond-CMOS technology. Although there are

  11. Physics of the atom

    CERN Document Server

    Wehr, Russell M; Adair, Thomas W

    1984-01-01

    The fourth edition of Physics of the Atom is designed to meet the modern need for a better understanding of the atomic age. It is an introduction suitable for students with a background in university physics and mathematical competence at the level of calculus. This book is designed to be an extension of the introductory university physics course into the realm of atomic physics. It should give students a proficiency in this field comparable to their proficiency in mechanics, heat, sound, light, and electricity.

  12. Nuclear Excitations by Antiprotons and Antiprotonic Atoms

    CERN Multimedia

    2002-01-01

    The proposal aims at the investigation of nuclear excitations following the absorption and annihilation of stopped antiprotons in heavier nuclei and at the same time at the study of the properties of antiprotonic atoms. The experimental arrangement will consist of a scintillation counter telescope for the low momentum antiproton beam from LEAR, a beam degrader, a pion multiplicity counter, a monoisotopic target and Ge detectors for radiation and charged particles. The data are stored by an on-line computer.\\\\ \\\\ The Ge detectors register antiprotonic x-rays and nuclear @g-rays which are used to identify the residual nucleus and its excitation and spin state. Coincidences between the two detectors will indicate from which quantum state the antiprotons are absorbed and to which nuclear states the various reactions are leading. The measured pion multiplicity characterizes the annihilation process. Ge&hyphn. and Si-telescopes identify charged particles and determine their energies.\\\\ \\\\ The experiment will gi...

  13. Beam Loss in Linacs

    CERN Document Server

    Plum, M.A.

    2016-01-01

    Beam loss is a critical issue in high-intensity accelerators, and much effort is expended during both the design and operation phases to minimize the loss and to keep it to manageable levels. As new accelerators become ever more powerful, beam loss becomes even more critical. Linacs for H- ion beams, such as the one at the Oak Ridge Spallation Neutron Source, have many more loss mechanisms compared to H+ (proton) linacs, such as the one being designed for the European Spallation Neutron Source. Interesting H- beam loss mechanisms include residual gas stripping, H+ capture and acceleration, field stripping, black-body radiation and the recently discovered intra-beam stripping mechanism. Beam halo formation, and ion source or RF turn on/off transients, are examples of beam loss mechanisms that are common for both H+ and H- accelerators. Machine protection systems play an important role in limiting the beam loss.

  14. DSMC Simulations of Hyperthermal Oxygen Beam Exposures

    Science.gov (United States)

    Cline, Jason A.; Braunstein, Matthew; Minton, Timothy K.

    2003-01-01

    Pulsed sources of hyper-thermal O-atoms are now being extensively used to simulate low-earth orbit (LEO) surface exposure environments. The peak flux of these sources is many orders of magnitude larger than the corresponding LEO flux. Although it is desirable to accelerate the test by using higher fluxes than found in LEO, even commonly used fluxes are large enough to produce multi-collision effects by causing a build-up of gas at the sample surface. In this paper we characterize the physical consequences to the experiment using the direct simulation Monte Carlo (DSMC) method. DSMC allows us to extract the distributions of energy and impact angle for the O-atoms that reach the surface, and to record how strongly the gas build-up at the target assembly deflects flux from downstream instrumentation. By considering a range of source fluxes, we determine the onset conditions and severity of these multi-collision effects. We find that even at common experimental fluxes with a normally incident beam striking a flat surface sample, the energy distribution of incident O-atoms broadens and develops a significant low-energy tail. The angular distributions also broaden significantly. The number of O-atoms that reach downstream instrumentation is decreased by approximately 50%. These simulations will aid in the calibration of ground-based O-atom measurements, and provide a model for the energy and angular distributions of O-atoms that actually impinge on surface samples.

  15. Beam Dynamics for ARIA

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl August Jr. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-10-14

    Beam dynamics issues are assessed for a new linear induction electron accelerator being designed for flash radiography of large explosively driven hydrodynamic experiments. Special attention is paid to equilibrium beam transport, possible emittance growth, and beam stability. It is concluded that a radiographic quality beam will be produced possible if engineering standards and construction details are equivalent to those on the present radiography accelerators at Los Alamos.

  16. Computer Model Of Fragmentation Of Atomic Nuclei

    Science.gov (United States)

    Wilson, John W.; Townsend, Lawrence W.; Tripathi, Ram K.; Norbury, John W.; KHAN FERDOUS; Badavi, Francis F.

    1995-01-01

    High Charge and Energy Semiempirical Nuclear Fragmentation Model (HZEFRG1) computer program developed to be computationally efficient, user-friendly, physics-based program for generating data bases on fragmentation of atomic nuclei. Data bases generated used in calculations pertaining to such radiation-transport applications as shielding against radiation in outer space, radiation dosimetry in outer space, cancer therapy in laboratories with beams of heavy ions, and simulation studies for designing detectors for experiments in nuclear physics. Provides cross sections for production of individual elements and isotopes in breakups of high-energy heavy ions by combined nuclear and Coulomb fields of interacting nuclei. Written in ANSI FORTRAN 77.

  17. Reconstruction of negative hydrogen ion beam properties from beamline diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Ruf, Benjamin

    2014-09-25

    For the experimental fusion reactor ITER, which should show the feasibility of sustaining a fusion plasma with a positive power balance, some technology still has to be developed, amongst others also the plasma heating system. One heating technique is the neutral beam injection (NBI). A beam of fast deuterium atoms is injected into the fusion plasma. By heavy particle collisions the beam particles give their energy to the plasma. A NBI system consists of three major components. First, deuterium ions are generated in a low temperature, low pressure plasma of an ion source. At ITER, the requirements on the beam energy of 1 MeV cause the necessity of negative charged deuterium ions. Secondly, the ions are accelerated within an acceleration system with several grids, where the plasma grid is the first grid. The grids are on different descending high voltage potentials. The source itself is on the highest negative potential. Thirdly, the fast deuterium ions have to be neutralised. This thesis deals with the second step in the mentioned beam system, the ion acceleration and beam formation. The underlying experiments and measurements were carried out at the testbeds BATMAN (BAvarianTest MAchine for Negative ions) and ELISE (Extraction from a Large Ion Source Experiment) at the Max-Planck-Institut fuer Plasmaphysik Garching (IPP Garching). The main goal of this thesis is to provide a tool which allows the determination of the beam properties. These are beam divergence, stripping losses and beam inhomogeneity. For this purpose a particle trajectory code has been developed from scratch, namely BBC-NI (Bavarian Beam Code for Negative Ions). The code is able to simulate the whole beam and the outcome of several beam diagnostic tools. The data obtained from the code together with the measurements of the beam diagnostic tools should allow the reconstruction of the beam properties. The major beam diagnostic tool, which is used in this thesis, is the beam emission spectroscopy

  18. Atomic & Molecular Interactions

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-07-12

    The Gordon Research Conference (GRC) on Atomic & Molecular Interactions was held at Roger Williams University, Bristol, RI. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  19. The Casimir atomic pendulum

    Energy Technology Data Exchange (ETDEWEB)

    Razmi, H. [Department of Physics, University of Qom, Qom 37185-359 (Iran, Islamic Republic of)], E-mail: razmi@qom.ac.ir; Abdollahi, M. [Department of Physics, University of Qom, Qom 37185-359 (Iran, Islamic Republic of)], E-mail: mah.abdollahi@gmail.com

    2008-11-10

    We want to introduce an atomic pendulum whose driving force (torque) is due to the quantum vacuum fluctuations. Applying the well-known Casimir-Polder effect to a special configuration (a combined structure of an atomic nanostring and a conducting plate), an atomic pendulum (Casimir atomic pendulum) is designed. Using practically acceptable data corresponding to the already known world of nanotechnology and based on reasonable/reliable numerical estimates, the period of oscillation for the pendulum is computed. This pendulum can be considered as both a new micro(nano)-electromechanical system and a new simple vacuum machine. Its design may be considered as a first step towards realizing the visualized vacuum (Casimir) clock{exclamation_point}.

  20. The Casimir atomic pendulum

    Science.gov (United States)

    Razmi, H.; Abdollahi, M.

    2008-11-01

    We want to introduce an atomic pendulum whose driving force (torque) is due to the quantum vacuum fluctuations. Applying the well-known Casimir-Polder effect to a special configuration (a combined structure of an atomic nanostring and a conducting plate), an atomic pendulum (Casimir atomic pendulum) is designed. Using practically acceptable data corresponding to the already known world of nanotechnology and based on reasonable/reliable numerical estimates, the period of oscillation for the pendulum is computed. This pendulum can be considered as both a new micro(nano)-electromechanical system and a new simple vacuum machine. Its design may be considered as a first step towards realizing the visualized vacuum (Casimir) clock!

  1. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1998-01-01

    This volume continues the series'' cutting-edge reviews on developments in this field. Since its invention in the 1920s, electrostatic precipitation has been extensively used in industrial hygiene to remove dust and particulate matter from gases before entering the atmosphere. This combination of electrostatic precipitation is reported upon in the first chapter. Following this, chapter two reviews recent advances in the area of chemical modification in electrothermal atomization. Chapter three consists of a review which deal with advances and uses of electrothermal atomization atomic absorption spectrometry. Flow injection atomic spectroscopy has developed rapidly in recent years and after a general introduction, various aspects of this technique are looked at in chapter four. Finally, in chapter five the use of various spectrometric techniques for the determination of mercury are described.

  2. Dalton's Atomic Theory

    National Research Council Canada - National Science Library

    DOBBIN, LEONARD

    1896-01-01

    WITH reference to the communications from the authors and from the reviewer of the "New View of the Origin of Dalton's Atomic Theory," published in NATURE for May 14, I beg leave to offer the following remarks...

  3. Atomic Interferometry Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Vertical cavity surface emitting lasers (VCSELs) is a new technology which can be used for developing high performance laser components for atom-based sensors...

  4. Topics in atomic physics

    CERN Document Server

    Burkhardt, Charles E

    2006-01-01

    The study of atomic physics propelled us into the quantum age in the early twentieth century and carried us into the twenty-first century with a wealth of new and, in some cases, unexplained phenomena. Topics in Atomic Physics provides a foundation for students to begin research in modern atomic physics. It can also serve as a reference because it contains material that is not easily located in other sources. A distinguishing feature is the thorough exposition of the quantum mechanical hydrogen atom using both the traditional formulation and an alternative treatment not usually found in textbooks. The alternative treatment exploits the preeminent nature of the pure Coulomb potential and places the Lenz vector operator on an equal footing with other operators corresponding to classically conserved quantities. A number of difficult to find proofs and derivations are included as is development of operator formalism that permits facile solution of the Stark effect in hydrogen. Discussion of the classical hydrogen...

  5. Zeeman atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hadeishi, T.; McLaughlin, R.

    1978-08-01

    The design and development of a Zeeman atomic absorption spectrometer for trace element analysis are described. An instruction manual is included which details the operation, adjustment, and maintenance. Specifications and circuit diagrams are given. (WHK)

  6. An Electromagnetic Beam Converter

    DEFF Research Database (Denmark)

    2009-01-01

    The present invention relates to an electromagnetic beam converter and a method for conversion of an input beam of electromagnetic radiation having a bell shaped intensity profile a(x,y) into an output beam having a prescribed target intensity profile l(x',y') based on a further development...

  7. Metaoptics for Spectral and Spatial Beam Manipulation

    Science.gov (United States)

    Raghu Srimathi, Indumathi

    Laser beam combining and beam shaping are two important areas with applications in optical communications, high power lasers, and atmospheric propagation studies. In this dissertation, metaoptical elements have been developed for spectral and spatial beam shaping, and multiplexing. Beams carrying orbital angular momentum (OAM), referred to as optical vortices, have unique propagation properties. Optical vortex beams carrying different topological charges are orthogonal to each other and have low inter-modal crosstalk which allows for them to be (de)multiplexed. Efficient spatial (de)multiplexing of these beams have been carried out by using diffractive optical geometrical coordinate transformation elements. The spatial beam combining technique shown here is advantageous because the efficiency of the system is not dependent on the number of OAM states being combined. The system is capable of generating coaxially propagating beams in the far-field and the beams generated can either be incoherently or coherently multiplexed with applications in power scaling and dynamic intensity profile manipulations. Spectral beam combining can also be achieved with the coordinate transformation elements. The different wavelengths emitted by fiber sources can be spatially overlapped in the far-field plane and the generated beams are Bessel-Gauss in nature with enhanced depth of focus properties. Unique system responses and beam shapes in the far-field can be realized by controlling amplitude, phase, and polarization at the micro-scale. This has been achieved by spatially varying the structural parameters at the subwavelength scale and is analogous to local modification of material properties. With advancements in fabrication technology, it is possible to control not just the lithographic process, but also the deposition process. In this work, a unique combination of spatial structure variations in conjunction with the conformal coating properties of an atomic layer deposition tool

  8. Wave Atom Based Watermarking

    OpenAIRE

    Bukhari, Ijaz; Nuhman-ul-Haq; Hyat, Khizar

    2013-01-01

    Watermarking helps in ensuring originality, ownership and copyrights of a digital image. This paper aims at embedding a Watermark in an image using Wave Atom Transform. Preference of Wave Atoms on other transformations has been due to its sparser expansion, adaptability to the direction of local pattern, and sharp frequency localization. In this scheme, we had tried to spread the watermark in an image so that the information at one place is very small and undetectable. In order to extract the...

  9. Hirshfeld atom refinement.

    Science.gov (United States)

    Capelli, Silvia C; Bürgi, Hans-Beat; Dittrich, Birger; Grabowsky, Simon; Jayatilaka, Dylan

    2014-09-01

    Hirshfeld atom refinement (HAR) is a method which determines structural parameters from single-crystal X-ray diffraction data by using an aspherical atom partitioning of tailor-made ab initio quantum mechanical molecular electron densities without any further approximation. Here the original HAR method is extended by implementing an iterative procedure of successive cycles of electron density calculations, Hirshfeld atom scattering factor calculations and structural least-squares refinements, repeated until convergence. The importance of this iterative procedure is illustrated via the example of crystalline ammonia. The new HAR method is then applied to X-ray diffraction data of the dipeptide Gly-l-Ala measured at 12, 50, 100, 150, 220 and 295 K, using Hartree-Fock and BLYP density functional theory electron densities and three different basis sets. All positions and anisotropic displacement parameters (ADPs) are freely refined without constraints or restraints - even those for hydrogen atoms. The results are systematically compared with those from neutron diffraction experiments at the temperatures 12, 50, 150 and 295 K. Although non-hydrogen-atom ADPs differ by up to three combined standard uncertainties (csu's), all other structural parameters agree within less than 2 csu's. Using our best calculations (BLYP/cc-pVTZ, recommended for organic molecules), the accuracy of determining bond lengths involving hydrogen atoms from HAR is better than 0.009 Å for temperatures of 150 K or below; for hydrogen-atom ADPs it is better than 0.006 Å(2) as judged from the mean absolute X-ray minus neutron differences. These results are among the best ever obtained. Remarkably, the precision of determining bond lengths and ADPs for the hydrogen atoms from the HAR procedure is comparable with that from the neutron measurements - an outcome which is obtained with a routinely achievable resolution of the X-ray data of 0.65 Å.

  10. Atoms, molecules & elements

    CERN Document Server

    Graybill, George

    2007-01-01

    Young scientists will be thrilled to explore the invisible world of atoms, molecules and elements. Our resource provides ready-to-use information and activities for remedial students using simplified language and vocabulary. Students will label each part of the atom, learn what compounds are, and explore the patterns in the periodic table of elements to find calcium (Ca), chlorine (Cl), and helium (He) through hands-on activities.

  11. Atomic Bomb Health Benefits

    OpenAIRE

    Luckey, T. D.

    2008-01-01

    Media reports of deaths and devastation produced by atomic bombs convinced people around the world that all ionizing radiation is harmful. This concentrated attention on fear of miniscule doses of radiation. Soon the linear no threshold (LNT) paradigm was converted into laws. Scientifically valid information about the health benefits from low dose irradiation was ignored. Here are studies which show increased health in Japanese survivors of atomic bombs. Parameters include decreased mutation,...

  12. Characterization of a metastable neon beam extracted from a commercial RF ion source

    CERN Document Server

    Ohayon, B; Ron, G

    2015-01-01

    We have used a commercial RF ion-source to extract a beam of metastable neon atoms. The source was easily incorporated into our existing system and was operative within a day of installation. The metastable velocity distribution, flux, flow, and efficiency were investigated for different RF powers and pressures, and an optimum was found at a flux density of $2\\times10^{12}\\,$atoms/s/sr. To obtain an accurate measurement of the amount of metastable atoms leaving the source, we insert a Faraday cup in the beam line and quench some of them using a weak $633\\,$nm laser beam. In order to determine how much of the beam was quenched before reaching our detector, we devised a simple model for the quenching transition and investigated it for different laser powers. This detection method can be easily adapted to other noble gas atoms.

  13. Atomic bomb and leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Ichimaru, M.; Tomonaga, M.; Amenomori, T.; Matsuo, T. (Nagasaki Univ. (Japan). School of Medicine)

    1991-12-01

    Characteristic features of the leukemia among atomic bomb survivors were studied. Dose estimates of atomic bomb radiation were based on T65D, but the new dosimetry system DS86 was used for some analyses. The ratio of a single leukemia type to all leukemias was highest for chronic myelogenous leukemia (CML) in Hiroshima, and the occurrence of CML was thought to be most characteristic to atomic bomb radiation induced leukemia. The threshold of CML occurrence in Hiroshima is likely to be between 0.5{approx}0.09 Gy. However, the threshold of acute leukemia appears to be nearly 1 Gy. In the distribution of acute myeloid leukemia (AML) subtypes by French-American-British classification, there was no M3 case in 1 Gy or more group, although several atypical AML cases of survivors were observed. Although aplastic anemia has not increased as a late effect of the atomic bomb radiation exposure, many atypical leukemia or other myeloproliferative diseases who had been diagnosed as aplastic anemia or its related diseases have been experienced among atomic bomb survivors. Chromosome study was conducted using colony forming cells induced by hemopoietic stem cells of peripheral blood of proximal survivors. Same chromosome aberrations were observed in colony forming cells and peripheral T-cells in several atomic bomb survivors. (author).

  14. Halo formation from mismatched beam-beam interactions

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Ji

    2003-05-23

    In this paper, we report on the halo formation and emittance growth driven by a parametric resonance during mismatched beam-beam collisions. In the regime of the weak-strong beam-beam interaction, if two beams have the same machine tunes, on-axis head-on collisions between a mismatched strong beam and a weak beam will not cause the formation of halo. However, if the two beams collide with an initial offset, the beam-beam force from the mismatched strong beam can cause halo formation and emittance growth in the weak beam. Meanwhile, if two beams have different machine tunes, for opposite charged colliding beams, when the machine tune of the weak beam is smaller than that of strong beam, there is emittance growth in the weak beam. When the machine tune of the weak beam is larger than that of the strong beam, there is little emittance growth. In the regime of strong-strong beam-beam interaction, halo is formed in both beams even when the two beams collide head-on on the axis with equal machine tunes. This puts a strong requirement for a good beam match during the injection to colliders in order to avoid the emittance growth.

  15. A high stability optical frequency reference based on thermal calcium atoms

    Science.gov (United States)

    2011-05-21

    simple, compact optical frequency standard based upon thennal calcium atoms. Using a Ramsey- Borde specu·ometer we excite features with linewidths < 5kHz...Optical Frequency (kHz) Figure 2: Ramsey- Borde fringes , shown here with both recoil components. Fringe width is < 5kHz (FWHM). tlli.s theoretical value...send ~ 2 m W of the light to a fom-beam Ramsey- Borde spectrometer that excites the atoms in a thermal beam [3]. Atoms emerge from an aperture in theCa

  16. Low-energy measurements of electron capture by multicharged ions from excited hydrogen atoms

    Energy Technology Data Exchange (ETDEWEB)

    Havener, C.C. (Oak Ridge National Laboratory, Oak Ridge, Tennesse 37831-6372 (United States)); Haque, M.A. (Alcorn State University, Lorman, Mississippi 39096 (United States)); Smith, A.C.H. (University College London, WC1E 6BT (United Kingdom)); Urbain, X. (Universite Catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve (Belgium)); Zeijlmans van Emmichoven, P.A. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6372 (United States) Joint Institute for Heavy Ion Research, Holifield Heavy Ion Research Facility, Oak Ridge, Tennessee 37831-6374 (United States))

    1993-06-05

    For very low collision energies electron capture from excited hydrogen by multicharged ions is characterized by enormous cross sections, the predicted maximum being comparable to the geometric size of the Rydberg atom. The ion-atom merged-beams technique is being used to study these collisions for the variety of charge states and the wide range of energies (0.1 to 1000 eV/amu) accessible to the apparatus. A neutral D beam containing a Rydberg atom population proportional to 1/n[sup 3] is produced by collisional electron detachment of 8 keV D[sup [minus

  17. Exponential beams of electromagnetic radiation

    OpenAIRE

    Bialynicki-Birula, Iwo; Bialynicka-Birula, Zofia

    2006-01-01

    We show that in addition to well known Bessel, Hermite-Gauss, and Laguerre-Gauss beams of electromagnetic radiation, one may also construct exponential beams. These beams are characterized by a fall-off in the transverse direction described by an exponential function of rho. Exponential beams, like Bessel beams, carry definite angular momentum and are periodic along the direction of propagation, but unlike Bessel beams they have a finite energy per unit beam length. The analysis of these beam...

  18. Distortion-free propagation in a chiral medium using the coherent superposition of atomic states

    Science.gov (United States)

    Ullah, Sana; Muhammad, Fayaz; Ullah, Irfan; Bacha, Bakht Amin; Arif Ullah, Sayed

    2017-11-01

    We propose a scheme for distortion free left/right circularly polarized beams in a chiral atomic medium in a tripod-type configuration using the superposition of atomic states. We measure and control the group index, group velocity and delay and advance times for left/right circularly polarized beams in a transparent chiral atomic medium by varying the population distribution probability in the superposition states. For the left and right circularly polarized beams of the probe field, delay and advance times have been observed at resonance and away from resonance. A negligible distortion and large phase shift in the left/right circularly polarized beams is theoretically investigated in the system. The results show potential applications in telecommunication, cloaking base technology and information processing.

  19. Atom interferometry with lithium atoms: theoretical analysis and design of an interferometer, applications; Interferometrie atomique avec l'atome de lithium: analyse theorique et construction d'un interferometre, applications

    Energy Technology Data Exchange (ETDEWEB)

    Champenois, C

    1999-12-01

    This thesis is devoted to studies which prepared the construction of an atom Mach-Zehnder interferometer. In such an interferometer, the propagating waves are spatially separated, and the internal state of the atom is not modified. The beam-splitters are diffraction gratings, consisting of standing optical waves near-resonant with an atomic transition. We use the Bloch functions to define the atom wave inside the standing wave grating and thus explain the diffraction process in different cases. We developed a nearly all-analytical model for the propagation of an atom wave inside a Mach-Zehnder interferometer. The contrast of the signal is studied for many cases: phase or amplitude gratings, effects of extra paths, effects of the main mismatches, monochromatic or lightly polychromatic sources. Finally, we discuss three interferometric measurements we think very interesting. The first, the index of refraction of gas for atomic waves, is studied in detail, with numerical simulations. The other measures we propose deal with the electrical properties of lithium. We discuss the ultimate limit for the measure of the static electric polarizability of lithium by atomic interferometry. Then, we discuss how one could measure the possible charge of the lithium atom. We conclude that an optically cooled and collimated atom beam would improve precision. (author)

  20. Multicharged optical vortices induced in a dissipative atomic vapor system

    CERN Document Server

    Zhang, Yiqi; Wu, Zhenkun; Yuan, Chenzhi; Wang, Ruimin; Lu, Keqing; Zhang, Yanpeng

    2013-01-01

    We investigate numerically the dynamics of optical vortex beams carrying different topological charges, launched in a dissipative three level ladder type nonlinear atomic vapor. We impose the electromagnetically induced transparency (EIT) condition on the medium. Linear, cubic, and quintic susceptibilities, considered simultaneously with the dressing effect, are included in the analysis. Generally, the beams slowly expand during propagation and new vortices are induced, commonly appearing in oppositely charged pairs. We demonstrate that not only the form and the topological charge of the incident beam, but also its growing size in the medium greatly affect the formation and evolution of vortices. We formulate common rules for finding the number of induced vortices and the corresponding rotation directions, stemming from the initial conditions of various incident beams, as well as from the dynamical aspects of their propagation. The net topological charge of the vortex is conserved during propagation, as it sh...

  1. Atomic magnetometer for human magnetoencephalograpy.

    Energy Technology Data Exchange (ETDEWEB)

    Schwindt, Peter; Johnson, Cort N.

    2010-12-01

    We have developed a high sensitivity (<5 fTesla/{radical}Hz), fiber-optically coupled magnetometer to detect magnetic fields produced by the human brain. This is the first demonstration of a noncryogenic sensor that could replace cryogenic superconducting quantum interference device (SQUID) magnetometers in magnetoencephalography (MEG) and is an important advance in realizing cost-effective MEG. Within the sensor, a rubidium vapor is optically pumped with 795 laser light while field-induced optical rotations are measured with 780 nm laser light. Both beams share a single optical axis to maximize simplicity and compactness. In collaboration with neuroscientists at The Mind Research Network in Albuquerque, NM, the evoked responses resulting from median nerve and auditory stimulation were recorded with the atomic magnetometer and a commercial SQUID-based MEG system with signals comparing favorably. Multi-sensor operation has been demonstrated with two AMs placed on opposite sides of the head. Straightforward miniaturization would enable high-density sensor arrays for whole-head magnetoencephalography.

  2. Fast ion atomic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Berry, H.G.; Young, L.; Goodman, L.S.; Somerville, L.P.; Hardis, J.; Neek, D.

    1984-01-01

    We have set up two collinear fast beam/laser excitation systems, one at the Argonne Dynamitron Accelerator (0.5 to 5.0 MeV beam energy) and another at a small electrostatic accelerator (20 to 130 keV). Our objective is to study fine structure, hyperfine structure and QED effects in ions of a few electrons. Initial projects underway include studies of multi-excited transitions in Li/sup -/ and Li/sup 0/, and transitions to high Rydberg states in H/sup 0/ and He/sup 0/. We have simultaneously excited a sodium jet with a laser at the resonance wavelength (D/sub 1/ or D/sub 2/ lines) and a 1-MeV He/sup +/ beam to produce excitation to autoionizing Na and Na/sup +/ states. The Auger electron spectra are compared to spectra obtained without laser excitation, and indicate strong variations in final state populations. 17 references.

  3. Lithium beam diagnostic system on the COMPASS tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Anda, G.; Bencze, A. [Wigner – RCP, HAS, Budapest (Hungary); Berta, M., E-mail: bertam@sze.hu [Institute of Plasma Physics AS CR, Prague (Czech Republic); Széchenyi István University, Győr (Hungary); Dunai, D. [Wigner – RCP, HAS, Budapest (Hungary); Hacek, P. [Institute of Plasma Physics AS CR, Prague (Czech Republic); Faculty of Mathematics and Physics, Charles University in Prague, Prague (Czech Republic); Krbec, J. [Institute of Plasma Physics AS CR, Prague (Czech Republic); Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague (Czech Republic); Réfy, D.; Krizsanóczi, T.; Bató, S.; Ilkei, T.; Kiss, I.G.; Veres, G.; Zoletnik, S. [Wigner – RCP, HAS, Budapest (Hungary)

    2016-10-15

    Highlights: • Li-beam diagnostic system on the COMPASS tokamak is an improved and compact system to allow testing of Atomic Beam Probe. • The possibility to measure background corrected density profiles on the few microseconds time scale. • First Li-beam diagnostic system with recirculating neutralizer. • The system includes the redesigned ion source with longer lifetime. - Abstract: An improved lithium beam based beam emission spectroscopy system – installed on COMPASS tokamak – is described. The beam energy enhanced up to 120 keV for Atomic Beam Probe measurement. The size of the ion source is doubled, using a newly developed thermionic heater instead of the conventionally used heating (tungsten or molybdenum) filament. The neutralizer is also improved. It produces the same sodium vapor in a cell but minimize the loss condensing the vapor on a cold surface which is led back (in fluid state) into the sodium oven. This way we call it recirculating neutralizer. The observation system consists of a CCD camera and an avalanche photodiode array.

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

    OpenAIRE

    Deltuva, A.

    2012-01-01

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

  5. Symmetric large momentum transfer for atom interferometry with BECs

    Science.gov (United States)

    Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Rasel, Ernst M.; Quantus Collaboration

    2017-04-01

    We develop and demonstrate a novel scheme for a symmetric large momentum transfer beam splitter for interferometry with Bose-Einstein condensates. Large momentum transfer beam splitters are a key technique to enhance the scaling factor and sensitivity of an atom interferometer and to create largely delocalized superposition states. To realize the beam splitter, double Bragg diffraction is used to create a superposition of two symmetric momentum states. Afterwards both momentum states are loaded into a retro-reflected optical lattice and accelerated by Bloch oscillations on opposite directions, keeping the initial symmetry. The favorable scaling behavior of this symmetric acceleration, allows to transfer more than 1000 ℏk of total differential splitting in a single acceleration sequence of 6 ms duration while we still maintain a fraction of approx. 25% of the initial atom number. As a proof of the coherence of this beam splitter, contrast in a closed Mach-Zehnder atom interferometer has been observed with up to 208 ℏk of momentum separation, which equals a differential wave-packet velocity of approx. 1.1 m/s for 87Rb. The presented work is supported by the CRC 1128 geo-Q and the DLR with funds provided by the Federal Ministry of Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under Grant No. DLR 50WM1552-1557 (QUANTUS-IV-Fallturm).

  6. Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS2.

    Science.gov (United States)

    Li, Huashan; Wang, Shanshan; Sawada, Hidetake; Han, Grace G D; Samuels, Thomas; Allen, Christopher S; Kirkland, Angus I; Grossman, Jeffrey C; Warner, Jamie H

    2017-03-28

    We have studied atomic level interactions between single Pt atoms and the surface of monolayer MoS2 using aberration-corrected annular dark field scanning transmission electron microscopy at an accelerating voltage of 60 kV. Strong contrast from single Pt atoms on the atomically resolved monolayer MoS2 lattice enables their exact position to be determined with respect to the MoS2 lattice, revealing stable binding sites. In regions of MoS2 free from surface contamination, the Pt atoms are localized in S vacancy sites and exhibit dynamic hopping to nearby vacancy sites driven by the energy supplied by the electron beam. However, in areas of MoS2 contaminated with carbon surface layers, the Pt atoms appear at various positions with respect to the underlying MoS2 lattice, including on top of Mo and in off-axis positions. These variations are due to the Pt bonding with the surrounding amorphous carbon layer, which disrupts the intrinsic Pt-MoS2 interactions, leading to more varied positions. Density functional theory (DFT) calculations reveal that Pt atoms on the surface of MoS2 have a small barrier for migration and are stabilized when bound to either a single or double sulfur vacancies. DFT calculations have been used to understand how the catalytic activity of the MoS2 basal plane for hydrogen evolution reaction is influenced by Pt dopants by variation of the hydrogen adsorption free energy. This strong dependence of catalytic effect on interfacial configurations is shown to be common for a series of dopants, which may provide a means to create and optimize reaction centers.

  7. Gamma Putty dosimetric studies in electron beam

    Directory of Open Access Journals (Sweden)

    Aime M Gloi

    2016-01-01

    Full Text Available Traditionally, lead has been used for field shaping in megavoltage electron beams in radiation therapy. In this study, we analyze the dosimetric parameters of a nontoxic, high atomic number (Z = 83, bismuth-loaded material called Gamma Putty that is malleable and can be easily molded to any desired shape. First, we placed an ionization chamber at different depths in a solid water phantom under a Gamma Putty shield of thickness (t = 0, 3, 5, 10, 15, 20, and 25 mm, respectively and measured the ionizing radiation on the central axis (CAX for electron beam ranging in energies from 6 to 20 MeV. Next, we investigated the relationship between the relative ionization (RI measured at a fixed depth for several Gamma Putty shield at different cutout diameters ranging from 2 to 5 cm for various beam energies and derived an exponential fitting equation for clinical purposes. The dose profiles along the CAX show that bremsstrahlung dominates for Gamma Putty thickness >15 mm. For high-energy beams (12-20 MeV and all Gamma Putty thicknesses up to 25 mm, RI below 5% could not be achieved due to the strong bremsstrahlung component. However, Gamma Putty is a very suitable material for reducing the transmission factor below 5% and protecting underlying normal tissues for low-energy electron beams (6-9 MeV.

  8. Atomic Spectroscopy and Collisions Using Slow Antiprotons \\\\ ASACUSA Collaboration

    CERN Multimedia

    Matsuda, Y; Lodi-rizzini, E; Kuroda, N; Schettino, G; Hori, M; Pirkl, W; Mascagna, V; Malbrunot, C L S; Yamazaki, Y; Eades, J; Simon, M; Massiczek, O; Sauerzopf, C; Nagata, Y; Knudsen, H; Uggerhoj, U I; Mc cullough, R W; Toekesi, K M; Venturelli, L; Widmann, E; Zmeskal, J; Kanai, Y; Hayano, R; Kristiansen, H; Todoroki, K; Bartel, M A; Moller, S P; Charlton, M; Leali, M; Diermaier, M; Kolbinger, B

    2002-01-01

    ASACUSA (\\underline{A}tomic \\underline{S}pectroscopy \\underline{A}nd \\underline{C}ollisions \\underline{U}sing \\underline{S}low \\underline{A}ntiprotons) is a collaboration between a number of Japanese and European research institutions, with the goal of studying bound and continuum states of antiprotons with simple atoms.\\\\ Three phases of experimentation are planned for ASACUSA. In the first phase, we use the direct $\\overline{p}$ beam from AD at 5.3 MeV and concentrate on the laser and microwave spectroscopy of the metastable antiprotonic helium atom, $\\overline{p}$He$^+$, consisting of an electron and antiproton bound by the Coulomb force to the helium nucleus. Samples of these are readily created by bringing AD antiproton beam bunches to rest in helium gas. With the help of techniques developed at LEAR for resonating high precision laser beams with antiproton transitions in these atoms, ASACUSA achieved several of these first-phase objectives during a few short months of AD operation in 2000. Six atomic tr...

  9. Two-Photon Excitation of Launched Cold Atoms in Flight

    Science.gov (United States)

    Goodsell, Anne; Gonzalez, Rene; Alejandro, Eduardo; Erwin, Emma

    2017-04-01

    We demonstrate two-photon bi-chromatic excitation of cold rubidium atoms in flight, using the pathway 5S1 / 2 -> 5P3 / 2 -> 5D5 / 2 with two resonant photons. In our experiment, atoms are laser-cooled in a magneto-optical trap and launched upward in discrete clouds with a controllable vertical speed of 7.1 +/-0.6 m/s and a velocity spread that is less than 10% of the launch speed. Outside the cooling beams, as high as 14 mm above the original center of the trap, the launched cold atoms are illuminated simultaneously by spatially-localized horizontal excitation beams at 780 nm (5S1 / 2 -> 5P3 / 2) and 776 nm (5P3 / 2 -> 5D5 / 2). We monitor transmission of the 780-nm beam over a range of intensities of 780-nm and 776-nm light. As the center of the moving cloud passes the excitation beams, we observe as much as 97.9 +/-1.2% transmission when the rate of two-photon absorption is high and the 5S1 / 2 and 5P3 / 2 states are depopulated, compared to 87.6 +/-0.9% transmission if only the 780-nm beam is present. This demonstrates two-photon excitation of a launched cold-atom source with controllable launch velocity and narrow velocity spread, as a foundation for three-photon excitation to Rydberg states. Research supported by Middlebury College Bicentennial Fund, Palen Fund, and Gladstone Award.

  10. Optimal design of beams

    Science.gov (United States)

    Samala, Shivakumar

    Beams are basic structural components that are capable of withstanding load primarily by resisting bending. Unlike Euler-Bernoulli beams, Timoshenko beams undergo both shear deformation and rotational effects, making it suitable for analyzing the behavior of thick or short beams, composite beams and beams that are subjected to high frequency excitation when their wave length becomes shorter. This thesis work focuses on optimal design of straight and tapered Timoshenko beams under static and dynamic constraints for rectangular and circular cross sections. In this work Timoshenko beam static and dynamic equations were studied. The finite element method was used for static and dynamic analysis of the beam. In finite element method to overcome the numerical problem in shear locking, cubic interpolation of displacement and an interdependent quadratic approximation of rotation has been considered. In order to optimize the weight of the beam with static and dynamic constraints three sets of optimizations were done. The design variables are length, cross sectional width and height, with objective function as mass, static deflection constraints were used. The second optimization set was using dynamic constraints and the last set was using both static and dynamic constraints.

  11. Resistance of steel beams with web openings and castellated beams

    OpenAIRE

    Kovačič, Darko

    2010-01-01

    In Diploma demonstration of bending and shear resistance of steel beams with openings in web and for castellated beams is being presented. Dimensioning of such beams is performed in compliance with general rules by Eurocode for dimensioning of beams by considering speciality of beams with openings or by non-linear analysis with consideration of imperfections. For delimit of beams with openings from castellated beams, geometric criteria are being used. Further approach to the dimensioning of t...

  12. Beam-Based Alignment in CTF3 Test Beam Line

    OpenAIRE

    Sterbini, G; Dӧbert, S; Marín, E.; Lillestol, RL; Schulte, D.; Adli, E.

    2012-01-01

    The CLIC linear collider is based on the two beams acceleration scheme. During acceleration of the colliding beams, the drive beam suffers a large build up on its energy spread. In order to efficiently transport such a beam, beam-based alignment techniques together with tight prealignment tolerances are crucial. To evaluate the performance of these steering algorithms, a beam-based steering campaign has been conducted at the Test Beam Line of the CLIC Test Facility. In the following we presen...

  13. A Transportable Gravity Gradiometer Based on Atom Interferometry

    Science.gov (United States)

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

    2010-01-01

    A transportable atom interferometer-based gravity gradiometer has been developed at JPL to carry out measurements of Earth's gravity field at ever finer spatial resolutions, and to facilitate high-resolution monitoring of temporal variations in the gravity field from ground- and flight-based platforms. Existing satellite-based gravity missions such as CHAMP and GRACE measure the gravity field via precise monitoring of the motion of the satellites; i.e. the satellites themselves function as test masses. JPL's quantum gravity gradiometer employs a quantum phase measurement technique, similar to that employed in atomic clocks, made possible by recent advances in laser cooling and manipulation of atoms. This measurement technique is based on atomwave interferometry, and individual laser-cooled atoms are used as drag-free test masses. The quantum gravity gradiometer employs two identical atom interferometers as precision accelerometers to measure the difference in gravitational acceleration between two points (Figure 1). By using the same lasers for the manipulation of atoms in both interferometers, the accelerometers have a common reference frame and non-inertial accelerations are effectively rejected as common mode noise in the differential measurement of the gravity gradient. As a result, the dual atom interferometer-based gravity gradiometer allows gravity measurements on a moving platform, while achieving the same long-term stability of the best atomic clocks. In the laboratory-based prototype (Figure 2), the cesium atoms used in each atom interferometer are initially collected and cooled in two separate magneto-optic traps (MOTs). Each MOT, consisting of three orthogonal pairs of counter-propagating laser beams centered on a quadrupole magnetic field, collects up to 10(exp 9) atoms. These atoms are then launched vertically as in an atom fountain by switching off the magnetic field and introducing a slight frequency shift between pairs of lasers to create a moving

  14. Sampling the Hydrogen Atom

    Directory of Open Access Journals (Sweden)

    Graves N.

    2013-01-01

    Full Text Available A model is proposed for the hydrogen atom in which the electron is an objectively real particle orbiting at very near to light speed. The model is based on the postulate that certain velocity terms associated with orbiting bodies can be considered as being af- fected by relativity. This leads to a model for the atom in which the stable electron orbits are associated with orbital velocities where Gamma is n /α , leading to the idea that it is Gamma that is quantized and not angular momentum as in the Bohr and other models. The model provides a mechanism which leads to quantization of energy levels within the atom and also provides a simple mechanical explanation for the Fine Struc- ture Constant. The mechanism is closely associated with the Sampling theorem and the related phenomenon of aliasing developed in the mid-20th century by engineers at Bell labs.

  15. Measurement of the density profile of pure and seeded molecular beams by femtosecond ion imaging

    NARCIS (Netherlands)

    Meng, C.; Janssen, M.H.M.

    2015-01-01

    Here, we report on femtosecond ion imaging experiments to measure the density profile of a pulsed supersonic molecular beam. Ion images are measured for both a molecular beam and bulk gas under identical experimental conditions via femtosecond multiphoton ionization of Xe atoms. We report the

  16. Atomic Force Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Day, R.D.; Russell, P.E.

    1988-12-01

    The Atomic Force Microscope (AFM) is a recently developed instrument that has achieved atomic resolution imaging of both conducting and non- conducting surfaces. Because the AFM is in the early stages of development, and because of the difficulty of building the instrument, it is currently in use in fewer than ten laboratories worldwide. It promises to be a valuable tool for obtaining information about engineering surfaces and aiding the .study of precision fabrication processes. This paper gives an overview of AFM technology and presents plans to build an instrument designed to look at engineering surfaces.

  17. Hirshfeld atom refinement

    Directory of Open Access Journals (Sweden)

    Silvia C. Capelli

    2014-09-01

    Full Text Available Hirshfeld atom refinement (HAR is a method which determines structural parameters from single-crystal X-ray diffraction data by using an aspherical atom partitioning of tailor-made ab initio quantum mechanical molecular electron densities without any further approximation. Here the original HAR method is extended by implementing an iterative procedure of successive cycles of electron density calculations, Hirshfeld atom scattering factor calculations and structural least-squares refinements, repeated until convergence. The importance of this iterative procedure is illustrated via the example of crystalline ammonia. The new HAR method is then applied to X-ray diffraction data of the dipeptide Gly–l-Ala measured at 12, 50, 100, 150, 220 and 295 K, using Hartree–Fock and BLYP density functional theory electron densities and three different basis sets. All positions and anisotropic displacement parameters (ADPs are freely refined without constraints or restraints – even those for hydrogen atoms. The results are systematically compared with those from neutron diffraction experiments at the temperatures 12, 50, 150 and 295 K. Although non-hydrogen-atom ADPs differ by up to three combined standard uncertainties (csu's, all other structural parameters agree within less than 2 csu's. Using our best calculations (BLYP/cc-pVTZ, recommended for organic molecules, the accuracy of determining bond lengths involving hydrogen atoms from HAR is better than 0.009 Å for temperatures of 150 K or below; for hydrogen-atom ADPs it is better than 0.006 Å2 as judged from the mean absolute X-ray minus neutron differences. These results are among the best ever obtained. Remarkably, the precision of determining bond lengths and ADPs for the hydrogen atoms from the HAR procedure is comparable with that from the neutron measurements – an outcome which is obtained with a routinely achievable resolution of the X-ray data of 0.65 Å.

  18. Optically pumped atoms

    CERN Document Server

    Happer, William; Walker, Thad

    2010-01-01

    Covering the most important knowledge on optical pumping of atoms, this ready reference is backed by numerous examples of modelling computation for optical pumped systems. The authors show for the first time that modern scientific computing software makes it practical to analyze the full, multilevel system of optically pumped atoms. To make the discussion less abstract, the authors have illustrated key points with sections of MATLAB codes. To make most effective use of contemporary mathematical software, it is especially useful to analyze optical pumping situations in the Liouville spa

  19. Atoms in Agriculture

    Energy Technology Data Exchange (ETDEWEB)

    Osborne, Thomas S. [University of Tennessee

    1965-01-01

    Agriculture benefits from the applications of research. Radioactive techniques have been used to study soils, plants, microbes, insects, farm animals, and new ways to use and preserve foodstuffs. Radioactive atoms are not used directly by farmers but are used in research directed by the U. S. Department of Agriculture and Atomic Energy Commission, by the agricultural experiment stations of the various states, and by numerous public and private research institutions. From such research come improved materials and methods which are used on the farm.

  20. From Atoms to Solids

    Science.gov (United States)

    1999-01-31

    Honea. M.L. Homer, J.L. Persson, R.L. Whetten , Chem. atoms Phys. Lett. 171 (1990) 147. [17] M.R. Hoare, Adv. Chem. Phys. 40 (1979) 49. Two types of...Persson, M.E. LaVilla, R.L. tal conditions, the clusters become rigid. Thereafter, Whetten , J. Phys. Chem. 93 (1989) 2869. each newly added atom condenses...106 (1981) 265. M. Broyer, Phys. Rev. A 39 (1989) 6056. [9] W. Ekardt, Ber. Bunsenges. Phys. Chem. 88 (1984) 289. [38] R.L. Whetten , private

  1. Korean atomic bomb victims.

    Science.gov (United States)

    Sasamoto, Yukuo

    2009-01-01

    After colonizing Korea, Japan invaded China, and subsequently initiated the Pacific War against the United States, Britain, and their allies. Towards the end of the war, U.S. warplanes dropped atomic bombs on Hiroshima and Nagasaki, which resulted in a large number of Koreans who lived in Hiroshima and Nagasaki suffering from the effects of the bombs. The objective of this paper is to examine the history of Korea atomic bomb victims who were caught in between the U.S., Japan, the Republic of Korea (South Korea) and the Democratic People's Republic of Korea (North Korea).

  2. Atomic bomb and leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Ichimaru, Michito; Tomonaga, Masao; Amenomori, Tatsuhiko; Matsuo, Tatsuki (Nagasaki Univ. (Japan). School of Medicine)

    1991-03-01

    Characteristic features of leukemia among atomic bomb survivors were studied. The ratio of a single leukemia type to all leukemias was highest for CML in Hiroshima, and the occurrence of CML was thought to be most characteristic for atomic bomb radiation induced leukemia. In the distribution of AML subtypes of FAB classification, there was no M3 cases in 1 Gy or more group, although several atypical AML cases of survivors were observed. Chromosome study was conducted using colony forming cells induced by hemopoietic stem cells of peripheral blood of proximal survivors. Same chromosome aberrations were observed in colony forming cells and peripheral blood of proximal survivors. (author).

  3. Time-resolved production and detection of reactive atoms

    Energy Technology Data Exchange (ETDEWEB)

    Grossman, L. W.; Hurst, G. S.

    1977-09-01

    Cesium iodide in the presence of a buffer gas was dissociated with a pulsed ultraviolet laser, which will be referred to as the source laser. This created a population of atoms at a well defined time and in a compact, well defined volume. A second pulsed laser, with a beam that completely surrounded that of the first, photoionized the cesium after a known time delay. This laser will be referred to as the detector laser. It was determined that for short time delays, all of the cesium atoms were easily ionized. When focused, the source laser generated an extremely intense fluence. By accounting for the beam intensity profile it was shown that all of the molecules in the central portion of the beam can be dissociated and detected. Besides proving the feasibility of single-molecule detection, this enabled a determination of the absolute photodissociation cross section as a function of wavelength. Initial studies of the time decay of the cesium signal at low argon pressures indicated a non-exponential decay. This was consistent with a diffusion mechanism transporting cesium atoms out of the laser beam. Therefore, it was desired to conduct further experiments using a tightly focused source beam, passing along the axis of the detector beam. The theoretical behavior of this simple geometry accounting for diffusion and reaction is easily calculated. A diffusion coefficient can then be extracted by data fitting. If reactive decay is due to impurities constituting a fixed percentage of the buffer gas, then two-body reaction rates will scale linearly with pressure and three-body reaction rates will scale quadratically. Also, the diffusion coefficient will scale inversely with pressure. At low pressures it is conceivable that decay due to diffusion would be sufficiently rapid that all other processes can be neglected. Extraction of a diffusion coefficient would then be quite direct. Finally, study of the reaction of cesium and oxygen was undertaken.

  4. Symposium on atomic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    1979-01-01

    Topics covered by the conference include: fast beam spectroscopy; astrophysical and other spectra; highly ionized spectroscopy; complex spectra; rydberg levels; fine structure, hyperfine structure and isotope shift; lineshapes; lifetimes, oscillator strengths and Einstein coefficients; and spectroscopy with lasers. Abstracts of the conference papers are presented. (GHT)

  5. Manipulating low-dimensional materials down to the level of single atoms with electron irradiation.

    Science.gov (United States)

    Susi, Toma; Meyer, Jannik C; Kotakoski, Jani

    2017-09-01

    Recent advances in scanning transmission electron microscopy (STEM) instrumentation have made it possible to focus electron beams with sub-atomic precision and to identify the chemical structure of materials at the level of individual atoms. Here we discuss the dynamics that are observed in the structure of low-dimensional materials under electron irradiation, and the potential use of electron beams for single-atom manipulation. As a demonstration of the latter capability, we show how momentum transfer from the electrons of a 60-keV Ångström-sized STEM probe can be used to move silicon atoms embedded in the graphene lattice with atomic precision. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Beam induced RF heating

    CERN Document Server

    Salvant, B; Arduini, G; Assmann, R; Baglin, V; Barnes, M J; Bartmann, W; Baudrenghien, P; Berrig, O; Bracco, C; Bravin, E; Bregliozzi, G; Bruce, R; Bertarelli, A; Carra, F; Cattenoz, G; Caspers, F; Claudet, S; Day, H; Garlasche, M; Gentini, L; Goddard, B; Grudiev, A; Henrist, B; Jones, R; Kononenko, O; Lanza, G; Lari, L; Mastoridis, T; Mertens, V; Métral, E; Mounet, N; Muller, J E; Nosych, A A; Nougaret, J L; Persichelli, S; Piguiet, A M; Redaelli, S; Roncarolo, F; Rumolo, G; Salvachua, B; Sapinski, M; Schmidt, R; Shaposhnikova, E; Tavian, L; Timmins, M; Uythoven, J; Vidal, A; Wenninger, J; Wollmann, D; Zerlauth, M

    2012-01-01

    After the 2011 run, actions were put in place during the 2011/2012 winter stop to limit beam induced radio frequency (RF) heating of LHC components. However, some components could not be changed during this short stop and continued to represent a limitation throughout 2012. In addition, the stored beam intensity increased in 2012 and the temperature of certain components became critical. In this contribution, the beam induced heating limitations for 2012 and the expected beam induced heating limitations for the restart after the Long Shutdown 1 (LS1) will be compiled. The expected consequences of running with 25 ns or 50 ns bunch spacing will be detailed, as well as the consequences of running with shorter bunch length. Finally, actions on hardware or beam parameters to monitor and mitigate the impact of beam induced heating to LHC operation after LS1 will be discussed.

  7. Laser beam shaping techniques

    Energy Technology Data Exchange (ETDEWEB)

    DICKEY,FRED M.; WEICHMAN,LOUIS S.; SHAGAM,RICHARD N.

    2000-03-16

    Industrial, military, medical, and research and development applications of lasers frequently require a beam with a specified irradiance distribution in some plane. A common requirement is a laser profile that is uniform over some cross-section. Such applications include laser/material processing, laser material interaction studies, fiber injection systems, optical data image processing, lithography, medical applications, and military applications. Laser beam shaping techniques can be divided into three areas: apertured beams, field mappers, and multi-aperture beam integrators. An uncertainty relation exists for laser beam shaping that puts constraints on system design. In this paper the authors review the basics of laser beam shaping and present applications and limitations of various techniques.

  8. Laser Beam Focus Analyser

    DEFF Research Database (Denmark)

    Nielsen, Peter Carøe; Hansen, Hans Nørgaard; Olsen, Flemming Ove

    2007-01-01

    The quantitative and qualitative description of laser beam characteristics is important for process implementation and optimisation. In particular, a need for quantitative characterisation of beam diameter was identified when using fibre lasers for micro manufacturing. Here the beam diameter limits...... the obtainable features in direct laser machining as well as heat affected zones in welding processes. This paper describes the development of a measuring unit capable of analysing beam shape and diameter of lasers to be used in manufacturing processes. The analyser is based on the principle of a rotating...... mechanical wire being swept through the laser beam at varying Z-heights. The reflected signal is analysed and the resulting beam profile determined. The development comprised the design of a flexible fixture capable of providing both rotation and Z-axis movement, control software including data capture...

  9. Planar electron beams in a wiggler magnet array

    Indian Academy of Sciences (India)

    2013-02-01

    Feb 1, 2013 ... Planar electron beams in a wiggler magnet array. ARTI HADAP1,∗ and K C MITTAL2. 1General Engineering Department, Terna Engineering College, Nerul, Navi Mumbai 400 706,. India. 2Accelerator and Pulsed Power Division, Bhabha Atomic Research Centre, Trombay,. Mumbai 400 085, India. ∗.

  10. Effects of ion beam irradiation on semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Nashiyama, Isamu; Hirao, Toshio; Itoh, Hisayoshi; Ohshima, Takeshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1997-03-01

    Energetic heavy-ion irradiation apparatus has been developed for single-event effects (SEE) testing. We have applied three irradiation methods such as a scattered-ion irradiation method, a recoiled-atom irradiation method, and a direct-beam irradiation method to perform SEE testing efficiently. (author)

  11. Application of electron beam technology in improving sewage water ...

    African Journals Online (AJOL)

    user

    2Radiation Technology Development Division, Bhabha Atomic Research Centre (BARC), Mumbai-400085, India. Accepted 30 May, 2011. The use of electron beam to disinfect sewage water is gaining importance. The current problem on environmental health in relation to water pollution insists for the safe disposal of ...

  12. Molecule-by-Molecule Writing Using a Focused Electron Beam

    DEFF Research Database (Denmark)

    Van Dorp, Willem F.; Zhang, Xiaoyan; Feringa, Ben L.

    2012-01-01

    The resolution of lithography techniques needs to be extended beyond their current limits to continue the trend of miniaturization and enable new applications. But what is the ultimate spatial resolution? It is known that single atoms can be imaged with a highly focused electron beam. Can single ...

  13. Testing fundamental symmetries using radioactive ion beams at ...

    Indian Academy of Sciences (India)

    The ISAC Facility at TRIUMF, Canada's national laboratory for particle and nuclear physics, provides rare isotope beams for a diverse research program. In this paper we summarize some recent experimental developments at TRIUMF pertaining to fundamental symmetry tests. These tests use the atomic nucleus as a probe ...

  14. Chilled beam application guidebook

    CERN Document Server

    Butler, David; Gräslund, Jonas; Hogeling, Jaap; Lund Kristiansen, Erik; Reinikanen, Mika; Svensson, Gunnar

    2007-01-01

    Chilled beam systems are primarily used for cooling and ventilation in spaces, which appreciate good indoor environmental quality and individual space control. Active chilled beams are connected to the ventilation ductwork, high temperature cold water, and when desired, low temperature hot water system. Primary air supply induces room air to be recirculated through the heat exchanger of the chilled beam. In order to cool or heat the room either cold or warm water is cycled through the heat exchanger.

  15. A large mode optical resonator for enhanced atom interferometry

    Science.gov (United States)

    Sapam, Ranjita Chanu; Mielec, Nicolas; Riou, Isabelle; Canuel, Benjamin; Holleville, David; Fang, Bess; Landragin, Arnaud; Geiger, Remi

    2017-04-01

    The development of atom interferometry in the last few decades has led to high precision measurements of inertial effects and tests of fundamental physics. New methods for higher sensitivity atom interferometers (AIs) are being explored, particularly the interrogation of atoms with optical cavities. Its benefits would be higher optical power allowing large momentum transfer beam splitters, and possibly cleaner and controlled phase profiles. However high sensitivity AIs require long interrogation times, which combined with cold atom expansion, bring the challenges of large waists in cavities. We propose an optical resonator composed of a convergent lens with two flat mirrors at its focal planes. This cavity is marginally stable and exhibits half degenerate behaviour. A numerical study of its behaviour, using an ABCD transfer matrix formalism, showed that typical controllable misalignments of a few micrometres would not be critical for atom interrogation. We realise this cavity with a 200 mm lens and an 8 μm input waist and a 7 mm waist Gaussian beam inside the cavity. ANR-10-LABX-48-01, ANR-11-EQPX-0028, city of Paris (HSENS-MWGRAV), CNRS GRAM, H2020 MC-Grant 660081- MWGRAV.

  16. Tunable dual-frequency laser source for coherent population trapping cesium atomic clocks

    Science.gov (United States)

    Camargo, F. A.; Georges, P.; Lucas-Leclin, G.; Baili, G.; Morvan, L.; Dolfi, D.; Holleville, D.; Guerandel, S.; Sagnes, I.

    2017-11-01

    Coherent population trapping (CPT) has been demonstrated as an interesting technique for miniature atomic frequency references [1,2] and quantum information. It is based on the coupling of the two hyperfine ground states of an alkali atom - namely cesium (133Cs) for atomic clocks - through excitation to a common atomic level by two phase-coherent laser fields nearly resonant with the atomic transitions. The frequency difference between the two laser fields is tuned at the atomic frequency splitting in the microwave range, equal to 9.192 GHz for 133Cs atoms. Outputs powers in the mW range and narrow-linewidth emission (<500 kHz) are required for the two laser beams.

  17. ALFA beam halo

    CERN Document Server

    Komarek, Tomas

    2014-01-01

    This note serves as a final report about CERN Summer Student Programme 2014 project. The beam halo is an undesired phenomenon for physics analyses on particle accelerators. It surrounds the beam core and constitutes an important part of background for signal measurements on some detectors, eg. in the forward region. In this study, the data from the ALFA detector were used, specifically from the run 191373 ($\\beta^*=90\\unit{m}$) and the run 213268 ($\\beta^*=1\\unit{km}$). Using the ROOT framework, a software for beam halo events selection was created and beam halo properties were examined. In the run 213268, excessive beam halo is suspected to be the reason for multiple beam scrapings that occurred. A kinematic reconstruction of beam halo particles is attempted in order to understand beam halo properties in the interaction point. Some further simulations are employed to find constraints for beam halo particles in order to survive in the accelerator for a longer time/many revolutions. This work represents a st...

  18. Beam cavity interaction

    CERN Document Server

    Gamp, A

    2011-01-01

    We begin by giving a description of the rf 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, rf feedback, and feed-forward are described. Examples of digital rf 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.

  19. Molecular beam sampling system with very high beam-to-background ratio: The rotating skimmer concept

    Science.gov (United States)

    Benedikt, J.; Ellerweg, D.; von Keudell, A.

    2009-05-01

    A novel method of reducing the background pressure in a vacuum system used for sampling a molecular beam from a high pressure region is presented. A triple differential pumping stage is constructed with a chopper with rotating skimmer within the first pumping stage, which serves effectively as a valve separating periodically the vacuum system from the ambient environment. The mass spectrometry measurement of the species in the molecular beam show an excellent beam-to-background ratio of 14 and a detection limit below 1 ppm. The potential of this method for detection of low density reactive species in atmospheric pressure plasmas is demonstrated for the detection of oxygen atoms generated in an atmospheric pressure microplasma source.

  20. Simulation of Beam-Beam Background at CLIC

    CERN Document Server

    Sailer, A

    2010-01-01

    The dense beams used at CLIC to achieve a high luminosity will cause a large amount of background particles through beam-beam interactions. Generator level studies with GUINEAPIG and full detector simulation studies with an ILD based CLIC detector have been performed to evaluate the amount of beam-beam back- ground hitting the vertex detector.

  1. Atomic Particle Detection

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Hal

    1970-01-01

    This booklet tells how scientists observe the particles and electromagnetic radiation that emerges from an atomic nucleus. The equipment used falls into two general categories: counters which count each particle as it passes by, and track detectors, which make a photographic record of the particle's track.

  2. FAC: Flexible Atomic Code

    Science.gov (United States)

    Gu, Ming Feng

    2018-02-01

    FAC calculates various atomic radiative and collisional processes, including radiative transition rates, collisional excitation and ionization by electron impact, energy levels, photoionization, and autoionization, and their inverse processes radiative recombination and dielectronic capture. The package also includes a collisional radiative model to construct synthetic spectra for plasmas under different physical conditions.

  3. Atomic physics and reality

    CERN Multimedia

    1985-01-01

    An account of the long standing debate between Niels Bohr and Albert Einstein regarding the validity of the quantum mechanical description of atomic phenomena.With physicts, John Wheeler (Texas), John Bell (CERN), David Rohm (London), Abner Shimony (Boston), Alain Aspect (Paris)

  4. Ludwig Boltzmann: Atomic genius

    Energy Technology Data Exchange (ETDEWEB)

    Cercignani, C. [Department of Mathematics, Politecnico di Milano (Italy)]. E-mail: carcer@mate.polimi.it

    2006-09-15

    On the centenary of the death of Ludwig Boltzmann, Carlo Cercignani examines the immense contributions of the man who pioneered our understanding of the atomic nature of matter. The man who first gave a convincing explanation of the irreversibility of the macroscopic world and the symmetry of the laws of physics was the Austrian physicist Ludwig Boltzmann, who tragically committed suicide 100 years ago this month. One of the key figures in the development of the atomic theory of matter, Boltzmann's fame will be forever linked to two fundamental contributions to science. The first was his interpretation of 'entropy' as a mathematically well-defined measure of the disorder of atoms. The second was his derivation of what is now known as the Boltzmann equation, which describes the statistical properties of a gas as made up of molecules. The equation, which described for the first time how a probability can evolve with time, allowed Boltzmann to explain why macroscopic phenomena are irreversible. The key point is that while microscopic objects like atoms can behave reversibly, we never see broken coffee cups reforming because it would involve a long series of highly improbable interactions - and not because it is forbidden by the laws of physics. (U.K.)

  5. Atomic Force Microscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 7. Atomic Force Microscopy - A Tool to Unveil the Mystery of Biological Systems ... Transcription and Disease Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 ...

  6. Observational Evidence for Atoms.

    Science.gov (United States)

    Jones, Edwin R., Jr.; Childers, Richard L.

    1984-01-01

    Discusses the development of the concept of atomicity and some of the many which can be used to establish its validity. Chemical evidence, evidence from crystals, Faraday's law of electrolysis, and Avogadro's number are among the areas which show how the concept originally developed from a purely philosophical idea. (JN)

  7. Use of atomic hydrogen source in collision: technological challenges

    Science.gov (United States)

    Hovey, R. T.; Vargas, E. L.; Panchenko, D. I.; Rivas, D. A.; Andrianarijaona, V. M.

    2015-03-01

    Atomic hydrogen was extensively studied in the past due to its obvious fundamental aspect. Also, quite few investigations were dedicated to atomic hydrogen sources because the results of experimental investigations on systems involving H would provide very rigorous tests for theoretical models. But even if atomic hydrogen sources are currently widespread in experimental physics, their uses in experiments on collisions are still very challenging mainly due to threefold problem. First, there is the difficulty to create H in the laboratory in sufficiently large number densities. Second, there is the strain to adjust the velocities of the produced atomic hydrogens. And third, there is the toil to control the internal energies of these atomic hydrogens. We will present an outline of different techniques using atomic hydrogen sources in collisions, which could be found in the literatures, such as merged-beam technique, gas cell technique, and trap, and propose an experiment scheme using a turn-key atomic hydrogen source that experiments such as charge transfer could benefit from. This work is supported by the National Science Foundation under Grant No. PHY-1068877.

  8. Three axis vector atomic magnetometer utilizing polarimetric technique

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, Swarupananda, E-mail: spradhan@barc.gov.in, E-mail: pradhans75@gmail.com [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400085, India and Homi Bhabha National Institute, Department of Atomic Energy, Mumbai 400094 (India)

    2016-09-15

    The three axis vector magnetic field measurement based on the interaction of a single elliptically polarized light beam with an atomic system is described. The magnetic field direction dependent atomic responses are extracted by the polarimetric detection in combination with laser frequency modulation and magnetic field modulation techniques. The magnetometer geometry offers additional critical requirements like compact size and large dynamic range for space application. Further, the three axis magnetic field is measured using only the reflected signal (one polarization component) from the polarimeter and thus can be easily expanded to make spatial array of detectors and/or high sensitivity field gradient measurement as required for biomedical application.

  9. Polarizing radioactive atoms from a MOT for β-decay studies

    Science.gov (United States)

    Gu, S.; Behr, J. A.; Melconian, D.; Cha, J.; Dube', P.; Eaton, S.; Groves, M.

    2001-05-01

    We have achieved >= 90% nuclear polarization of ^41K by trapping ^41K atoms in a weak B field environment using a time-cycled MOT, and optically pumping with an additional circular polarized D1 laser beam. The circular polarized D1 beam (S_1/2 to P_1/2 transition), can in principle optically pump the atoms to the maximum angular momentum F =2, MF = 2 state, where both nucleus and atomic angular momentum are fully polarized. The non-zero B field condition is realized by attenuating the retroreflected beams of the MOT in the horizontal plane, so the trapped atom cloud's equilibrium position is moved to finite B field. Then an additional uniform B field is applied along the axis to move the atoms back to the original MOT center. The polarizing process is to turn MOT beams and D1 beam on and off alternatively; the D1 fluorescence is monitored to measure the polarization while the MOT is off. We have also applied this technique to polarize radioactive ^37K, which has almost identical hyperfine structure, to study its nuclear β decays. *Supported by NSERC and CIPI.

  10. Atomic Parity Non Conservation with Francium atoms in the FrPNC collaboration

    Science.gov (United States)

    Zhang, Jiehang; Aubin, Seth; Behr, John A.; Collister, Robert; Flambaum, Victor V.; Gomez, Eduardo; Gwinner, Gerald; Melconian, Dan; Orozco, Luis A.; Pearson, Matt R.; Shelbaya, Olivier; Sprouse, Gene D.; Tandecki, Michael; Voss, Annika

    2012-06-01

    The FrPNC collaboration is dedicated to the study of the nuclear weak interaction through measurements of Parity Violation in francium atoms. We are preparing to measure both the nuclear spin independent part of the interaction that results in the determination of the weak charge and the nuclear spin dependent part dominated by the anapole moment. The experiment has moved to TRIUMF in a room carefully shielded from RF noise. The Fr production at TRIUMF is on the isotope range of A=203-229 with yields up to 10^8 s-1, giving us access to both the neutron deficient and rich sides. An ion optics system at the end of the beam line delivers the Fr ions to the neutralizer. The trapping side has been successfully tested with rubidium. The complete system delivers cold and trapped atomic Fr in a robust way to the science chamber where the measurements will take place.

  11. Orbital Angular Momentum of Gauge Fields: Excitation of AN Atom by Twisted Photons

    Science.gov (United States)

    Afanasev, Andrei; Carlson, Carl E.; Mukherjee, Asmita

    2014-01-01

    Twisted photon states, or photon states with large (> ℏ) angular momentum projection in the direction of motion, can photoexcite atomic final states of differing quantum numbers. If the photon symmetry axis coincides with the center of an atom, there are known selection rules that require exact matching between the quantum numbers of the photon and the photoexcited states. The more general case of arbitrarily positioned beams relaxes the selection rules but produces a distribution of quantum numbers of the final atomic states that is novel and distinct from final states produced by plane-wave photons. Numerical calculations are presented using a hydrogen atom as an example.

  12. Laser-cooled atoms inside a hollow-core photonic-crystal fiber

    DEFF Research Database (Denmark)

    Bajcsy, Michal; Hofferberth, S.; Peyronel, Thibault

    2011-01-01

    We describe the loading of laser-cooled rubidium atoms into a single-mode hollow-core photonic-crystal fiber. Inside the fiber, the atoms are confined by a far-detuned optical trap and probed by a weak resonant beam. We describe different loading methods and compare their trade-offs in terms...... of implementation complexity and atom-loading efficiency. The most efficient procedure results in loading of ∼30,000 rubidium atoms, which creates a medium with an optical depth of ∼180 inside the fiber. Compared to our earlier study this represents a sixfold increase in the maximum achieved optical depth...

  13. Molecular beam simulation of planetary atmospheric entry: Some recent results

    Science.gov (United States)

    French, J. B.; Reid, N. M.

    1972-01-01

    Molecular beam sources for producing fast beams containing CO2 and atomic oxygen are discussed. Results pertinent to the design and calibration of mass spectrometer ion source for measurement of the Martian atmosphere during the free molecule portion of the entry trajectory are also presented. The shortcomings and advantages of the simulation technique are discussed. It is shown that an open cavity configuration retains sensitivity to atomic oxygen, provides reasonable signal enhancement from the stagnation effect, is not highly sensitive to pitch and yaw effects, and presents no unforeseen problems in measuring CO2 or atomic oxygen. The simulation techniques used provide assistance in designing, developing, and (potentially) in testing and calibrating the required flight instrument.

  14. High intensity proton beam transportation through fringe field of 70 MeV compact cyclotron to beam line targets

    Science.gov (United States)

    Zhang, Xu; Li, Ming; Wei, Sumin; Xing, Jiansheng; Hu, Yueming; Johnson, Richard R.; Piazza, Leandro; Ryjkov, Vladimir

    2016-06-01

    From the stripping points, the high intensity proton beam of a compact cyclotron travels through the fringe field area of the machine to the combination magnet. Starting from there the beams with various energy is transferred to the switching magnet for distribution to the beam line targets. In the design of the extraction and transport system for the compact proton cyclotron facilities, such as the 70 MeV in France and the 100 MeV in China, the space charge effect as the beam crosses the fringe field has not been previously considered; neither has the impact on transverse beam envelope coupled from the longitudinal direction. Those have been concerned much more with the higher beam-power because of the beam loss problem. In this paper, based on the mapping data of 70 MeV cyclotron including the fringe field by BEST Cyclotron Inc (BEST) and combination magnet field by China Institute of Atomic Energy (CIAE), the beam extraction and transport are investigated for the 70 MeV cyclotron used on the SPES project at Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro (INFN-LNL). The study includes the space charge effect and longitudinal and transverse coupling mentioned above, as well as the matching of beam optics using the beam line for medical isotope production as an example. In addition, the designs of the ±45° switching magnets and the 60° bending magnet for the extracted beam with the energy from 35 MeV to 70 MeV have been made. Parts of the construction and field measurements of those magnets have been done as well. The current result shows that, the design considers the complexity of the compact cyclotron extraction area and fits the requirements of the extraction and transport for high intensity proton beam, especially at mA intensity levels.

  15. Determination of molecular, atomic, electronic cross-sections and effective atomic number of some boron compounds and TSW

    Energy Technology Data Exchange (ETDEWEB)

    Icelli, Orhan [Department of physics Education, Faculty of Education Erzincan University, 24030 Erzincan (Turkey)], E-mail: orhanicelli@gmail.com; Erzeneoglu, Salih [Department of physics, Faculty of Sciences, Atatuerk University, Erzurum (Turkey); Boncukcuoglu, Recep [Department of Environmental Engineering, Faculty of Engineering, Atatuerk University, Erzurum (Turkey)

    2008-07-15

    The transmission of gamma-rays of some boron compounds (H{sub 3}BO{sub 3}, Na{sub 2}B{sub 4}O{sub 7}) and the trommel sieve waste (TSW) have been measured by using an extremely narrow-collimated-beam transmission method in the energy range 15.74-40.93 keV. Molecular, atomic and electronic cross-sections and effective atomic numbers have been determinated on the basis of mixture rule and compared with the results obtained from theory.

  16. Atomic resolution imaging and spectroscopy of barium atoms and functional groups on graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Boothroyd, C.B., E-mail: ChrisBoothroyd@cantab.net [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Moreno, M.S. [Centro Atómico Bariloche, 8400 – San Carlos de Bariloche (Argentina); Duchamp, M.; Kovács, A. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Monge, N.; Morales, G.M.; Barbero, C.A. [Department of Chemistry, Universidad Nacional de Río Cuarto, X5804BYA Río Cuarto (Argentina); Dunin-Borkowski, R.E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany)

    2014-10-15

    We present an atomic resolution transmission electron microscopy (TEM) and scanning TEM (STEM) study of the local structure and composition of graphene oxide modified with Ba{sup 2+}. In our experiments, which are carried out at 80 kV, the acquisition of contamination-free high-resolution STEM images is only possible while heating the sample above 400 °C using a highly stable heating holder. Ba atoms are identified spectroscopically in electron energy-loss spectrum images taken at 800 °C and are associated with bright contrast in high-angle annular dark-field STEM images. The spectrum images also show that Ca and O occur together and that Ba is not associated with a significant concentration of O. The electron dose used for spectrum imaging results in beam damage to the specimen, even at elevated temperature. It is also possible to identify Ba atoms in high-resolution TEM images acquired using shorter exposure times at room temperature, thereby allowing the structure of graphene oxide to be studied using complementary TEM and STEM techniques over a wide range of temperatures. - Highlights: • Graphene oxide modified with Ba{sup 2+} was imaged using TEM and STEM at 80 kV. • High-resolution images and spectra were obtained only by heating above 400 °C. • Elemental maps show the distribution of C, Ba, O and Ca on the graphene oxide. • Single Ba atoms were identified in STEM HAADF and HRTEM images.

  17. Automated beam model optimization.

    Science.gov (United States)

    Létourneau, Daniel; Sharpe, Michael B; Owrangi, Amir; Jaffray, David A

    2010-05-01

    The beam model in a three dimensional treatment planning system (TPS) defines virtually the mechanical and dosimetric characteristics of a treatment unit. The manual optimization of a beam model during commissioning can be a time consuming task due to its iterative nature. Furthermore, the quality of the beam model commissioning depends on the user's ability to manage multiple parameters and assess their impact on the agreement between measured and calculated dose. The objective of this work is to develop and validate the performance of an automated beam model optimization system (ABMOS) based on intensity modulated radiotherapy (IMRT) beam measurements to improve beam model accuracy while streamlining the commissioning process. The ABMOS was developed to adjust selected TPS beam model parameters iteratively to maximize the agreement between measured and calculated 2D dose maps obtained for an IMRT beam pattern. A 2D diode array with high spatial resolution detectors was used to sample the entire IMRT beam pattern in a single dose measurement. The use of an IMRT beam pattern with large number of monitor units was selected to highlight the difference between planned and delivered dose and improve the signal to noise ratio in the low dose regions. ABMOS was applied to the optimization of a beam model for an Elekta Synergy S treatment unit. The optimized beam model was validated for two anatomical sites (25 paraspinal and 25 prostate cases) using two independent patient-specific IMRT quality control (QC) methods based on ion chamber and 2D diode array measurements, respectively. The conventional approach of comparing calculated and measured beam profiles and percent-depth dose curves was also used to assess improvement in beam model after ABMOS optimization. Elements of statistical process control were applied to the process of patient-specific QC performed with the ion chamber and the 2D array to complement the model comparison. After beam model optimization with

  18. Modelling the Energetics of Encapsulation of Atoms and Atomic ...

    Indian Academy of Sciences (India)

    user

    2015-07-04

    Jul 4, 2015 ... Modelling the Energetics of Encapsulation of. Atoms and Atomic Clusters into Carbon. Nanotubes: Insights from Analytical Approaches. R. S. Swathi. School of Chemistry. Indian Institute of Science Education and Research. Thiruvananthapuram, Kerala, India ...

  19. Role of atoms in atomic gravitational-wave detectors

    Science.gov (United States)

    Norcia, Matthew A.; Cline, Julia R. K.; Thompson, James K.

    2017-10-01

    Recently, it has been proposed that space-based atomic sensors may be used to detect gravitational waves. These proposals describe the sensors either as clocks or as atom interferometers. Here, we seek to explore the fundamental similarities and differences between the two types of proposals. We present a framework in which the fundamental mechanism for sensitivity is identical for clock and atom interferometer proposals, with the key difference being whether or not the atoms are tightly confined by an external potential. With this interpretation in mind, we propose two major enhancements to detectors using confined atoms, which allow for an enhanced sensitivity analogous to large momentum transfer used in atom interferometry (though with no transfer of momentum to the atoms), and a way to extend the useful coherence time of the sensor beyond the atom's excited-state lifetime.

  20. A carbon contamination cleaning of gold film by electron beam irradiation with minimum structural damages

    Science.gov (United States)

    Park, D. J.; Kang, T. H.; Kim, D. S.; Kim, H. T.; Choi, S. B.

    2017-10-01

    We demonstrate a successful removal of carbon contamination in gold surface simply by exposing relatively low energy electron emitted from field effect scanning electron microscope apparatus. An atomic force microscope image of gold film taken after a few tens of minute exposure of electron beam indicates small morphology change, however, a lateral force microscope image taken simultaneously shows a considerable increase of surface potential, which suggest an effective change of atomic composition between gold and other contaminant atoms as carbon. Energy-dispersive X-ray spectroscopy confirms that the carbon composition is substantially decreased due to electron beam exposure.

  1. Diagnostics for hot plasmas using hydrogen neutral beams

    Energy Technology Data Exchange (ETDEWEB)

    Goldston, R.J.

    1982-12-01

    Beams of neutral hydrogen atoms have found a number of uses in the diagnosis of hot plasmas. In the most straightforward application, neutral beams have been used to determine plasma line density, based on simple attenuation measurements. This technique has been applied most intensively recently to the study of beam-injected mirror plasmas. Neutral beams have also now been used in a number of tokamaks to supply a local increase of the neutral atom target density for charge exchange. By directing a time-modulated neutral beam across the sight-line of a charge-exchange analyzer, and measuring the modulated neutral particle efflux from the plasma, local measurements of the ion energy distribution function can be made. If a modulated diagnostic neutral beam is directed across the sight-line of an ultra-violet spectrometer, one can also make measurements of the local densities and possibly velocity distributions of fully stripped impurities. The fast hydrogen neutrals charge exchange with fully stripped impurities in the plasma, leaving the impurities in excited hydrogen-like states. In their prompt radiative decay the impurity ions emit characteristic uv lines, which can be detected easily.

  2. Beam Injection into RHIC

    Science.gov (United States)

    Fischer, W.; Hahn, H.; Mackay, W. W.; Tsoupas, N.

    1997-05-01

    During the RHIC sextant test in January 1997 beam was injected into a sixth of one of the rings for the first time. We describe the injection zone and its bottlenecks, the application program to steer the beam and the injection kickers. We report on the commissioning of the injection systems and on measurements of the kickers.

  3. Durnin-Whitney beams

    Science.gov (United States)

    de Jesús Cabrera-Rosas, Omar; Espíndola-Ramos, Ernesto; Alejandro Juárez-Reyes, Salvador; Julián-Macías, Israel; Ortega-Vidals, Paula; Rickenstorff-Parrao, Carolina; Silva-Ortigoza, Gilberto; Silva-Ortigoza, Ramón; Sosa-Sánchez, Citlalli Teresa

    2017-05-01

    The aim of the present work is to define a Durnin-Whitney beam as a nondiffracting beam such that its associated caustic locally only has singularities of the fold and cusp types. Since the caustic is structurally stable then the intensity pattern of this beam is also stable and this property is what makes its definition and its theoretical and experimental study worthwhile. These properties are important in applications such as uniform optical drilling in waveguides and communications through weak turbulent atmosphere. We find that in accordance with Whitney's theorem on the stability of maps from a two-dimensional manifold to a two-dimensional manifold the phase g({{Φ }}), of the complex function A({{Φ }}) characterizing the beam, locally is given by g({{Φ }})=a{{Φ }} for a fold and g({{Φ }})=b{{{Φ }}}2 for a cusp. This result implies that the Bessel beam of order zero is not stable and that any other Bessel beam is stable because locally it has a caustic of fold type. Finally, we present an example of a Durnin-Whitney beam given by g({{Φ }})=m{{Φ }}+b{{{Φ }}}2, which is a natural generalization of the Bessel beam of order m with a singularity of cusp ridge type.

  4. Beam Diagnostics for Accelerators

    CERN Document Server

    Koziol, Heribert

    2005-01-01

    This introductory course aims at a reasonably complete coverage of beam diagnostic devices used in linear and circular accelerators and in primary beam lines. The weight is on the concepts and the indication of variants, while for technical details the reader is referred to the literature. The present updated version replaces those from previous General Accelerator Physics Courses.

  5. Detecting Bessel beams

    Science.gov (United States)

    Trichili, Abderrahmen; Mhlanga, Thandeka; Ismail, Yaseera; Roux, Filippus S.; McLaren, Melanie; Zghal, Mourad; Forbes, Andrew

    2014-09-01

    We propose a 2-dimensional method for Bessel Gaussian beam azimuthal and radial decomposition using digital holograms. We illustrate the reconstruction of a Bessel Gaussian beam after encountering an obstruction. From the measured decomposition we show the reconstruction of the amplitude, phase and azimuthal index of the field with high degree of accuracy.

  6. Laser Beam Scanning Device.

    Science.gov (United States)

    metal mirror. Multiple thermocouple wires attached to the rear of the mirror provide temperature (and hence beam power) information at various points...on the mirror. Scanning is achieved by means of a selector switch which sequentially samples the thermocouple outputs. The thermocouple output voltages are measured and recorded as a function of laser beam power.

  7. Extraction dynamics of electrons from magneto-optically trapped atoms

    Science.gov (United States)

    Fedchenko, Olena; Chernov, Sergii; McCulloch, Andrew; Vielle-Grosjean, Mélissa; Comparat, Daniel; Schönhense, Gerd

    2017-07-01

    Pulsed photoionization of laser-cooled atoms in a magneto-optical trap (MOT) has the potential to create cold electron beams of few meV bandwidths and few ps pulse lengths. Such a source would be highly attractive for the study of fast low-energy processes like coherent phonon excitation. To study the suitability of MOT-based sources for the production of simultaneously cold and fast electrons, we study the photoionization dynamics of trapped Cs atoms. A momentum-microscope-like setup with a delay-line detector allows for the simultaneous measurement of spatial and temporal electron distributions. The measured patterns are complex, due to the Lorentz force inducing spiral trajectories. Ray-tracing simulations reproduce the main features. We find that the production of electron bunches with bandwidths of a few meV is straightforward; however, pulses in the ps-range are more demanding and require beam blanking or partial blocking.

  8. Spectral features of electromagnetically induced absorption in 85Rb atoms

    Science.gov (United States)

    Rehman, Hafeez-ur; Adnan, Muhammad; Noh, Heung-Ryoul; Kim, Jin-Tae

    2015-06-01

    We present theoretical and experimental studies of electromagnetically induced absorption (EIA) for the {{F}g}=3\\to {{F}e}=4 transition of 85Rb-D2 line. From the results calculated by solving time-dependent density-matrix equations including the optical and Zeeman coherences connected via three-photon interactions, the EIA signals have ultra-narrow feature in low powers of coupling beam in both same- and orthogonal-polarization configurations for both stationary and thermal atoms. However, the ultra-narrow EIA signals from high powers of coupling laser beam still remained in the ultra-narrow state only in the same-polarization configuration for thermal atoms. The calculated results match well with experimental results except ultra-narrow EIA region considering linewidths of two separate coupling and probe lasers.

  9. Search for a permanent EDM with laser cooled radioactive atom

    Science.gov (United States)

    Sakemi, Yasuhiro

    2014-09-01

    To explore the mechanism for the generation of the matter-antimatter asymmetry in the universe, the study on fundamental symmetry violation using the trapped radioactive atoms with laser cooling techniques is being promoted. An Electric Dipole Moment (EDM) of the elementary particle is a good prove to observe the phenomena beyond the Standard Model. A finite value of EDM means the violation of the time reversal symmetry, and the CP violation under the CPT invariance. In paramagnetic atoms, an electron EDM results in an atomic EDM enhanced by the factor of the 3rd power of the charge of the nucleus due the relativistic effects. A heaviest alkali element francium (Fr), which is the radioactive atom, has the largest enhancement factor K ~ 895 in atomic system. Then, we are developing a high intensity laser cooled Fr factory at Cyclotron and Radioisotope Center (CYRIC), Tohoku University to search for the EDM of Fr with the accuracy of 10-29 e cm. To overcome the current accuracy limit of the EDM, it is necessary to realize the high intensity Fr source and to reduce the systematic error due to the motional magnetic field and inhomogeneous applied field. To reduce the dominant component of the systematic errors mentioned above, we will confine the Fr atoms in the small region with the Magneto-Optical Trap (MOT) and optical lattice using the laser cooling and trapping techniques. The construction of the experimental apparatus is making progress, and the new thermal ionizer already produces the Fr of ~ 10 6 ions/s with the primary beam intensity 200 nA. The extracted Fr ion beam is transported to the neutralizer, which is located 10 m downstream, and the produced neutral Fr atoms are introduced into the MOT to load the next trapping system such as the optical dipole force trap and optical lattice. The coherence time will be increased in the laser trapping system, and the present status of the experiment will be reported.

  10. The ASACUSA experiment at CERN's AD antiproton decelerator catches antiprotons in helium, where the antiprotons replace electrons, giving exotics atoms.

    CERN Multimedia

    Loïez, P

    2000-01-01

    Photo 03: Laser beams are prepared for shooting at antiprotonic helium atoms. Left to right: Masaki Hori (Tokyo University) and John Eades (CERN). Photo 01: Dye laser triggered by "YAG" laser. Photo 02: Masaki Hori adjusting optical system of laser beams.

  11. Sheet electron beam tester

    Science.gov (United States)

    Spear, Alexander Grenbeaux

    The DARPA HiFIVE project uses a pulsed electron sheet beam gun to power a traveling wave tube amplifier operating at 220 GHz. Presented is a method for characterizing the high current density 0.1 mm by 1 mm sheet electron beam. A tungsten tipped probe was scanned through the cross section of the sheet electron beam inside of a vacuum vessel. The probe was controlled with sub-micron precision using stepper motors and LabView computer control while boxcar averaging hardware sampled the pulsed beam. Matlab algorithms were used to interpret the data, calculate beam dimensions and current density, and create 2-dimensional cross section images. Full characterization of two separate HiFIVE sheet electron guns was accomplished and is also presented.

  12. Mechanically reinforced glass beams

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes

    2007-01-01

    The use of glass as a load carrying material in structural elements is rarely seen even though glass is a popular material for many architects. This is owed to the unreliable and low tensile strength, which is due to surface flaws and high brittleness of the material. These properties lead...... to breakage without any warning or ductility, which can be catastrophic if no precautions are taken. One aspect of this issue is treated here by looking at the possibility of mechanically reinforcing glass beams in order to obtain ductile failure for such a structural component. A mechanically reinforced...... laminated float glass beam is constructed and tested in four-point bending. The beam consist of 4 layers of glass laminated together with a slack steel band glued onto the bottom face of the beam. The glass parts of the tested beams are \\SI{1700}{mm} long and \\SI{100}{mm} high, and the total width of one...

  13. Beam director design report

    Energy Technology Data Exchange (ETDEWEB)

    Younger, F.C.

    1986-08-01

    A design and fabrication effort for a beam director is documented. The conceptual design provides for the beam to pass first through a bending and focusing system (or ''achromat''), through a second achromat, through an air-to-vacuum interface (the ''beam window''), and finally through the vernier steering system. Following an initial concept study for a beam director, a prototype permanent magnet 30/sup 0/ beam-bending achromat and prototype vernier steering magnet were designed and built. In volume II, copies are included of the funding instruments, requests for quotations, purchase orders, a complete set of as-built drawings, magnetic measurement reports, the concept design report, and the final report on the design and fabrication project. (LEW)

  14. Production of transversely cooled, spin-polarized pulse beam from a low-velocity intense source of rubidium

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Eu Seok; Kim, Ji Yeon; Park, Chang Yong; Cho, D. [Korea University, Seoul (Korea, Republic of)

    1998-11-01

    In this experiment we studied the possibility of producing a pulsed beam for greater instantaneous beam flux, cooling the beam transversely to increase the effective beam flux and finally optical pumping to produce spin polarized atomic beam. We successfully and reliably produced a pulsed beam, and observed definite transverse cooling of the beam. We developed rather elaborate control program and interface hardware to produce the pulsed beam, and transversely cool, optically pump, and detect the atoms. We have produced the low-velocity intense source(LVIS) beam and operated it in a pulsed mode. Using an electronically controlled shutter we could load a Magneto Optical Trap(MOT) for 1 sec and launched a pulse of rubidium atoms. We performed the transverse cooling experiment using the pulses. In order to detect how the cooling is working, we used a slit to narrow down the probe beam. The probe beam had a width of 1 mm and we scanned it using a micrometer-controlled translational stage. (Cho, G.S.). 7 refs., 2 figs.

  15. Atomic Absorption, Atomic Fluorescence, and Flame Emission Spectrometry.

    Science.gov (United States)

    Horlick, Gary

    1984-01-01

    This review is presented in six sections. Sections focus on literature related to: (1) developments in instrumentation, measurement techniques, and procedures; (2) performance studies of flames and electrothermal atomizers; (3) applications of atomic absorption spectrometry; (4) analytical comparisons; (5) atomic fluorescence spectrometry; and (6)…

  16. Transportation of a radioactive ion beam for precise laser-trapping experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Hirokazu; Inoue, T. [Frontier Research Institute for Interdisciplinary Sciences (FRIS), Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Cyclotron and Radioisotope Center (CYRIC), Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Ando, S.; Aoki, T.; Arikawa, H.; Harada, K.; Hayamizu, T.; Ishikawa, T.; Itoh, M.; Kato, K.; Köhler, L.; Sakamoto, K.; Uchiyama, A.; Sakemi, Y. [Cyclotron and Radioisotope Center (CYRIC), Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578 (Japan)

    2016-02-15

    Francium is the heaviest species among the alkali elements. Due to its properties, francium is said to be of advantage in measurements of tiny observations, such as atomic parity violation and electric dipole moment. Before executing experiments with francium, it must be produced artificially because it is one of the most unstable elements. We produced francium with the nuclear fusion reaction of an oxygen beam and gold target, ionized the produced francium through a thermal ionization process, and extracted the ion with electrostatic fields. However, the thermal ionization process is known to ionize not only an objective atom but also other atomic species. Therefore, a Wien filter was installed to analyze the composition of the ion beam and purify the beam. This allowed us to improve the beam purity from ∼10{sup −6} to ∼10{sup −3}.

  17. Transportation of a radioactive ion beam for precise laser-trapping experiments

    Science.gov (United States)

    Kawamura, Hirokazu; Ando, S.; Aoki, T.; Arikawa, H.; Harada, K.; Hayamizu, T.; Inoue, T.; Ishikawa, T.; Itoh, M.; Kato, K.; Köhler, L.; Sakamoto, K.; Uchiyama, A.; Sakemi, Y.

    2016-02-01

    Francium is the heaviest species among the alkali elements. Due to its properties, francium is said to be of advantage in measurements of tiny observations, such as atomic parity violation and electric dipole moment. Before executing experiments with francium, it must be produced artificially because it is one of the most unstable elements. We produced francium with the nuclear fusion reaction of an oxygen beam and gold target, ionized the produced francium through a thermal ionization process, and extracted the ion with electrostatic fields. However, the thermal ionization process is known to ionize not only an objective atom but also other atomic species. Therefore, a Wien filter was installed to analyze the composition of the ion beam and purify the beam. This allowed us to improve the beam purity from ˜10-6 to ˜10-3.

  18. Cavity enhanced atomic magnetometry.

    Science.gov (United States)

    Crepaz, Herbert; Ley, Li Yuan; Dumke, Rainer

    2015-10-20

    Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations.

  19. Cavity enhanced atomic magnetometry

    CERN Document Server

    Crepaz, Herbert; Dumke, Rainer

    2015-01-01

    Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations.

  20. Atomes et rayonnement

    OpenAIRE

    Dalibard, Jean; Haroche, Serge

    2013-01-01

    Matière et lumière sont intimement liées dans notre modélisation du monde physique. De l’élaboration de la théorie quantique à l’invention du laser, l’interaction entre atomes et rayonnement a joué un rôle central dans le développement de la science et de la technologie d’aujourd’hui. La maîtrise de cette interaction permet désormais d’atteindre les plus basses températures jamais mesurées. Le refroidissement de gaz d’atomes par la lumière d’un laser conduit à une « matière quantique » aux pr...

  1. Atomic emission spectroscopy

    Science.gov (United States)

    Andrew, K. H.

    1975-01-01

    The relationship between the Slater-Condon theory and the conditions within the atom as revealed by experimental data was investigated. The first spectrum of Si, Rb, Cl, Br, I, Ne, Ar, and Xe-136 and the second spectrum of As, Cu, and P were determined. Methods for assessing the phase stability of fringe counting interferometers and the design of an autoranging scanning system for digitizing the output of an infrared spectrometer and recording it on magnetic tape are described.

  2. Nano Electronics on Atomically Controlled van der Waals Quantum Heterostructures

    Science.gov (United States)

    2015-03-30

    Final 3. DATES COVERED (From - To) 14 Aug 13 to 13 Feb 15 4. TITLE AND SUBTITLE Nano Electronics on Atomically Controlled van der Waals ...dimensional (2D) van der Waals (vdW) materials for the realization of novel quantum electronic states. We employed molecular beam epitaxy (MBE) combined with...junctions that allowed to study transport across the van der Waals interface between the conductor and superconductor. Our observation of gate tunable

  3. Atomic hydrogen induced defect kinetics in amorphous silicon

    NARCIS (Netherlands)

    Peeters, F. J. J.; Zheng, J.; Aarts, I. M. P.; Pipino, A. C. R.; Kessels, W. M. M.; van de Sanden, M. C. M.

    2017-01-01

    Near-infrared evanescent-wave cavity ring-down spectroscopy (CRDS) has been applied to study the defect evolution in an amorphous silicon (a-Si:H) thin film subjected to a directed beam of atomic H with a flux of (0.4–2) × 1014 cm−2 s−1. To this end, a 42 ± 2 nm a-Si:H film was grown on the total

  4. Improved atomic force microscopy cantilever performance by partial reflective coating

    OpenAIRE

    Zeno Schumacher; Yoichi Miyahara; Laure Aeschimann; Peter Grütter

    2015-01-01

    Optical beam deflection systems are widely used in cantilever based atomic force microscopy (AFM). Most commercial cantilevers have a reflective metal coating on the detector side to increase the reflectivity in order to achieve a high signal on the photodiode. Although the reflective coating is usually much thinner than the cantilever, it can still significantly contribute to the damping of the cantilever, leading to a lower mechanical quality factor (Q-factor). In dynamic mode operation in ...

  5. Beam monitoring at NA2

    CERN Multimedia

    1978-01-01

    Claus Goessling working on the beam Cerenkov counter of NA2. The muon beam enters from left the hall EHN2 and the last element of the beam transport. On background is the access door on the Jura side.

  6. Into the atom and beyond

    CERN Document Server

    1989-01-01

    Magnifying an atom to football pitch size. The dense nucleus, carrying almost all the atomic mass, is much smaller than the ball. The players (the electrons) would see something about the size of a marble!

  7. Nuclear effects in atomic transitions

    CERN Document Server

    Pálffy, Adriana

    2011-01-01

    Atomic electrons are sensitive to the properties of the nucleus they are bound to, such as nuclear mass, charge distribution, spin, magnetization distribution, or even excited level scheme. These nuclear parameters are reflected in the atomic transition energies. A very precise determination of atomic spectra may thus reveal information about the nucleus, otherwise hardly accessible via nuclear physics experiments. This work reviews theoretical and experimental aspects of the nuclear effects that can be identified in atomic structure data. An introduction to the theory of isotope shifts and hyperfine splitting of atomic spectra is given, together with an overview of the typical experimental techniques used in high-precision atomic spectroscopy. More exotic effects at the borderline between atomic and nuclear physics, such as parity violation in atomic transitions due to the weak interaction, or nuclear polarization and nuclear excitation by electron capture, are also addressed.

  8. Interaction between single gold atom and the graphene edge: A study via aberration-corrected transmission electron microscopy

    KAUST Repository

    Wang, Hongtao

    2012-01-01

    Interaction between single noble metal atoms and graphene edges has been investigated via aberration-corrected and monochromated transmission electron microscopy. A collective motion of the Au atom and the nearby carbon atoms is observed in transition between energy-favorable configurations. Most trapping and detrapping processes are assisted by the dangling carbon atoms, which are more susceptible to knock-on displacements by electron irradiation. Thermal energy is lower than the activation barriers in transition among different energy-favorable configurations, which suggests electron-beam irradiation can be an efficient way of engineering the graphene edge with metal atoms. © 2012 The Royal Society of Chemistry.

  9. Formation of two-dimensional nonspreading atomic wave packets in the field of two standing light waves

    NARCIS (Netherlands)

    Efremov, MA; Petropavlovsky, SV; Fedorov, MV; Schleich, WP; Yakovlev, VP

    The formation of two-dimensional nonspreading atomic wave packets produced in the interaction of a beam of two-level atoms with two standing light waves polarised in the same plane is considered. The mechanism providing a dispersionless particle dynamics is the balance of two processes: a rapid

  10. Atomic and Molecular Physics Program

    Science.gov (United States)

    2013-03-05

    Atomic Quantum Memories in Nano-Scale Optical Circuits: Jeff Kimble, Oskar Painter (CalTech) • Demonstration of a nanofiber atom trap: A. Goban...et al, Phys. Rev. Lett. 109, 033603 (2012) • Cavity QED with atomic mirrors: D. Chang, et al, N. J. Phys. 14, 063003 (2012) • Fiber -coupled chip... PMMA -diamond hybrid cavities, coupling stable NV centers • Cavity Optomechanics with Cold Atoms: Dan Stamper-Kurn (UC Berkeley) • Squeezed light

  11. On the non-linear spectroscopy including saturated absorption and four-wave mixing in two and multi-level atoms: a computational study

    Science.gov (United States)

    Patel, M.; De Jager, G.; Nkosi, Z.; Wyngaard, A.; Govender, K.

    2017-10-01

    In this paper we report on the study of two and multi-level atoms interacting with multiple laser beams. The semi-classical approach is used to describe the system in which the atoms are treated quantum mechanically via the density matrix operator, while the laser beams are treated classically using Maxwells equations. We present results of a two level atom interacting with single and multiple laser beams and demonstrate Rabi oscillations between the levels. The effects of laser modulation on the dynamics of the atom (atomic populations and coherences) are examined by solving the optical Bloch equations. Plots of the density matrix elements as a function of time are presented for various parameters such as laser intensity, detuning, modulation etc. In addition, phase-space plots and Fourier analysis of the density matrix elements are provided. The atomic polarization, estimated from the coherence terms of the density matrix elements, is used in the numerical solution of Maxwells equations to determine the behaviour of the laser beams as they propagate through the atomic ensemble. The effects of saturation and hole-burning are demonstrated in the case of two counter propagating beams with one being a strong beam and the other being very weak. The above work is extended to include four-wave mixing in four level atoms in a diamond configuration. Two co-propagating beams of different wavelengths drive the atoms from a ground state |1〉 to an excited state |3〉 via an intermediate state |2〉. The atoms then move back to the ground state via another intermediate state |4〉, resulting in the generation of two additional correlated photon beams. The characteristics of these additional photons are studied.

  12. Beam Imaging and Luminosity Calibration

    CERN Document Server

    AUTHOR|(CDS)2081126; Klute, Markus; Medlock, Catherine Aiko

    2016-01-01

    We discuss a method to reconstruct two-dimensional proton bunch densities using vertex distributions accumulated during LHC beam-beam scans. The x-y correlations in the beam shapes are studied and an alternative luminosity calibration technique is introduced. We demonstrate the method on simulated beam-beam scans and estimate the uncertainty on the luminosity calibration associated to the beam-shape reconstruction to be below 1%.

  13. Perspective: Oxide molecular-beam epitaxy rocks!

    Directory of Open Access Journals (Sweden)

    Darrell G. Schlom

    2015-06-01

    Full Text Available Molecular-beam epitaxy (MBE is the “gold standard” synthesis technique for preparing semiconductor heterostructures with high purity, high mobility, and exquisite control of layer thickness at the atomic-layer level. Its use for the growth of multicomponent oxides got off to a rocky start 30 yr ago, but in the ensuing decades, it has become the definitive method for the preparation of oxide heterostructures too, particularly when it is desired to explore their intrinsic properties. Examples illustrating the unparalleled achievements of oxide MBE are given; these motivate its expanding use for exploring the potentially revolutionary states of matter possessed by oxide systems.

  14. Lasers, Understanding the Atom Series.

    Science.gov (United States)

    Hellman, Hal

    This booklet is one of the booklets in the "Understanding the Atom Series" published by the U. S. Atomic Energy Commission for high school science teachers and their students. Basic information for understanding the laser is provided including discussion of the electromagnetic spectrum, radio waves, light and the atom, coherent light, controlled…

  15. Breaking the atom with Samson

    NARCIS (Netherlands)

    Väänänen, J.; Coecke, B.; Ong, L.; Panangaden, P.

    2013-01-01

    The dependence atom =(x,y) was introduced in [11]. Here x and y are finite sets of attributes (or variables) and the intuitive meaning of =(x,y) is that the attributes x completely (functionally) determine the attributes y. One may wonder, whether the dependence atom is truly an atom or whether it

  16. Current Trends in Atomic Spectroscopy.

    Science.gov (United States)

    Wynne, James J.

    1983-01-01

    Atomic spectroscopy is the study of atoms/ions through their interaction with electromagnetic radiation, in particular, interactions in which radiation is absorbed or emitted with an internal rearrangement of the atom's electrons. Discusses nature of this field, its status and future, and how it is applied to other areas of physics. (JN)

  17. Bohmian picture of Rydberg atoms

    Indian Academy of Sciences (India)

    lished the nearly elliptical shapes for the centre-of-mass motion in Rydberg atoms using numerical simulations, we show analytically that the Bohmian trajectories in Rydberg atoms are nearly ellipti- cal. Keywords. Rydberg atom; quantum trajectory. PACS No. 03.65.Ge. 1. Introduction. Ever since the advent of quantum ...

  18. Beam propagation factors and kurtosis parameters of a Lorentz-Gauss vortex beam.

    Science.gov (United States)

    Zhou, Guoquan

    2014-06-01

    Based on the second-order and the higher-order moments, analytical expressions for the beam propagation factors of a Lorentz-Gauss vortex beam with l=1 have been derived, and analytical propagation expressions for the kurtosis parameters of a Lorentz-Gauss vortex beam with l=1 through a paraxial and real ABCD optical system have also been presented. The M² factor is determined by the parameters a and b and decreases with increasing the parameter a or b. The M² factor is validated to be larger than 2. The kurtosis parameters depend on the diffraction-free ranges of the Lorentz part, the parameters a and b, and the ratio A/B. The kurtosis parameters of a Lorentz-Gauss vortex beam propagating in free space are demonstrated in different reference planes. In the far field, the kurtosis parameter K decreases with increasing one of the parameters a and b. Upon propagation, the kurtosis parameter K first decreases, then increases, and finally tends to a saturated value. In any case, the kurtosis parameter K is larger than 2. This research is beneficial to optical trapping, guiding, and manipulation of microscopic particles and atoms using Lorentz-Gauss vortex beams.

  19. Chemical Reactions of Molecules Promoted and Simultaneously Imaged by the Electron Beam in Transmission Electron Microscopy.

    Science.gov (United States)

    Skowron, Stephen T; Chamberlain, Thomas W; Biskupek, Johannes; Kaiser, Ute; Besley, Elena; Khlobystov, Andrei N

    2017-08-15

    The main objective of this Account is to assess the challenges of transmission electron microscopy (TEM) of molecules, based on over 15 years of our work in this field, and to outline the opportunities in studying chemical reactions under the electron beam (e-beam). During TEM imaging of an individual molecule adsorbed on an atomically thin substrate, such as graphene or a carbon nanotube, the e-beam transfers kinetic energy to atoms of the molecule, displacing them from equilibrium positions. Impact of the e-beam triggers bond dissociation and various chemical reactions which can be imaged concurrently with their activation by the e-beam and can be presented as stop-frame movies. This experimental approach, which we term ChemTEM, harnesses energy transferred from the e-beam to the molecule via direct interactions with the atomic nuclei, enabling accurate predictions of bond dissociation events and control of the type and rate of chemical reactions. Elemental composition and structure of the reactant molecules as well as the operating conditions of TEM (particularly the energy of the e-beam) determine the product formed in ChemTEM processes, while the e-beam dose rate controls the reaction rate. Because the e-beam of TEM acts simultaneously as a source of energy for the reaction and as an imaging tool monitoring the same reaction, ChemTEM reveals atomic-level chemical information, such as pathways of reactions imaged for individual molecules, step-by-step and in real time; structures of illusive reaction intermediates; and direct comparison of catalytic activity of different transition metals filmed with atomic resolution. Chemical transformations in ChemTEM often lead to previously unforeseen products, demonstrating the potential of this method to become not only an analytical tool for studying reactions, but also a powerful instrument for discovery of materials that can be synthesized on preparative scale.

  20. Simulations of beam-beam and beam-wire interactions in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung J.; Sen, Tanaji; /Fermilab; Abreu, Natalia P.; Fischer, Wolfram; /Brookhaven

    2009-02-01

    The beam-beam interaction is one of the dominant sources of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and strong localized long-range beam-beam effects are experimentally investigated in the RHIC collider. Tune shift, beam transfer function, and beam loss rate are measured in dedicated experiments. In this paper, they report on simulations to study the effect of beam-wire interactions based on diffusive apertures, beam loss rates, and beam transfer function using a parallelized weak-strong beam simulation code (BBSIMC). The simulation results are compared with measurements performed in RHIC during 2007 and 2008.

  1. Measurement of the density profile of pure and seeded molecular beams by femtosecond ion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Congsen [LaserLaB Amsterdam, VU University Amsterdam, de Boelelaan 1083, 1081 HV Amsterdam (Netherlands); Department of Physics, National University of Defense Technology, Changsha 410073 (China); Janssen, Maurice H. M. [LaserLaB Amsterdam, VU University Amsterdam, de Boelelaan 1083, 1081 HV Amsterdam (Netherlands)

    2015-02-15

    Here, we report on femtosecond ion imaging experiments to measure the density profile of a pulsed supersonic molecular beam. Ion images are measured for both a molecular beam and bulk gas under identical experimental conditions via femtosecond multiphoton ionization of Xe atoms. We report the density profile of the molecular beam, and the measured absolute density is compared with theoretical calculations of the centre line beam density. Subsequently, we discuss reasons accounting for the differences between measurements and calculations and propose that strong skimmer interference is the most probable cause for the differences. Furthermore, we report on experiments measuring the centre line density of seeded supersonic beams. The femtosecond ion images show that seeding the heavy Xe atom at low relative seed fractions (1%-10%) in a light carrier gas like Ne results in strong relative enhancements of up to two orders of magnitude.

  2. Nuclear astrophysics and the Daresbury Recoil Separator at the Holifield Radioactive Ion Beam Facility

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.S.

    1997-12-01

    The Daresbury Recoil Separator (DRS) has been installed for nuclear astrophysics research at Oak Ridge National Laboratory`s Holifield Radioactive Ion Beam Facility. It will be used for direct measurements of capture reactions on radioactive ions which occur in stellar explosions such as novae, supernovae and X-ray bursts. These measurements will be made in inverse kinematics with radioactive heavy ion beams incident on hydrogen and helium targets, and the DRS will separate the capture reaction recoils from the intense flux of beam particles. Details of the new DRS experimental equipment and preliminary results from the first commissioning experiments with stable beams are described, along with the plans for the first measurements with radioactive beams. Other astrophysics research efforts at ORNL--in theoretical astrophysics, nuclear astrophysics data evaluation, heavy element nucleosynthesis, theoretical atomic astrophysics, and atomic astrophysics data--are also briefly described.

  3. Imaging with neutral atoms: a new matter-wave microscope.

    Science.gov (United States)

    Koch, M; Rehbein, S; Schmahl, G; Reisinger, T; Bracco, G; Ernst, W E; Holst, B

    2008-01-01

    Matter-wave microscopy can be dated back to 1932 when Max Knoll and Ernst Ruska published the first image obtained with a beam of focussed electrons. In this paper a new step in the development of matter-wave microscopy is presented. We have created an instrument where a focussed beam of neutral, ground-state atoms (helium) is used to image a sample. We present the first 2D images obtained using this new technique. The imaged sample is a free-standing hexagonal copper grating (with a period of about 36 microm and rod thickness of about 8 microm). The images were obtained in transmission mode by scanning the focussed beam, which had a minimum spot size of about 2.0 microm in diameter (full width at half maximum) across the sample. The smallest focus achieved was 1.9 +/- 0.1 microm. The resolution for this experiment was limited by the speed ratio of the atomic beam through the chromatic aberrations of the zone plate that was used to focus. Ultimately the theoretical resolution limit is set by the wavelength of the probing particle. In praxis, the resolution is limited by the source and the focussing optics.

  4. ICFA Beam Dynamics Newsletter

    Energy Technology Data Exchange (ETDEWEB)

    Pikin, A. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-11-21

    Electron beam ion sources technology made significant progress since 1968 when this method of producing highly charged ions in a potential trap within electron beam was proposed by E. Donets. Better understanding of physical processes in EBIS, technological advances and better simulation tools determined significant progress in key EBIS parameters: electron beam current and current density, ion trap capacity, attainable charge states. Greatly increased the scope of EBIS and EBIT applications. An attempt is made to compile some of EBIS engineering problems and solutions and to demonstrate a present stage of understanding the processes and approaches to build a better EBIS.

  5. Beam instrumentation performance overview

    CERN Document Server

    Sapinski, M

    2012-01-01

    The 2011 run has proven that LHC can operate safely and stably with higher bunch intensity and smaller transverse emittance than foreseen in the Technical Design Report. In this presentation the performance of the Beam Position Monitoring (BPM) system is discussed. The improvements to the system, those made during the last year and those expected to be done for 2012 run are presented. The status of the three types of devices measuring the transverse beam emittance, wire scanners (BWS), synchrotron radiation monitors (BSRT) and beam gas ionization monitors (BGI), are shown. The control room applications are reviewed and a set of improvements proposed by the operation team is presented.

  6. Luminescent beam stop

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, Diane; Morton, Simon A.

    2017-10-25

    This disclosure provides systems, methods, and apparatus related to beam stops. In one aspect, a device comprises a luminescent material, a beam stop plate, and an optical fiber. The luminescent material is a parallelepiped having a first side and a second side that are squares and having a third side that is a rectangle or a square. The first side and the second side are perpendicular to the third side. The beam stop plate is attached to the first side of the luminescent material. The optical fiber has a first end and a second end, with the first end of the optical fiber attached to the third side of the luminescent material.

  7. Proceedings of the international seminar on atomic processes in plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Takako; Murakami, Izumi [eds.

    2000-01-01

    The International Seminar on Atomic Processes in Plasmas (ISAPP), a satellite meeting to the ICPEAC was held July 28-29 at the National Institute for Fusion Science in Toki, Gifu, Japan. About 110 scientists attended the ISAPP meeting and discussed atomic processes and atomic data required for fusion research. This Proceedings book includes the papers of the talks, posters and panel discussion given at the meeting. The invited talks described the super configuration array method for complex spectra, near-LTE atomic kinetics, R-matrix calculations, the binary-encounter dipole model for electron-impact ionization of molecules, other calculations of molecular processes, the ADAS project and the NIFS atomic data-base, and a survey of the role of molecular processes in divertor plasmas. On the experimental side crossed-beam ion-ion collision-experiments for charge transfer, and storage-ring and EBIT measurements of ionization, excitation and dielectronic recombination cross-sections were presented, and atomic processes important for x-ray laser experiments and x-ray spectroscopy of astrophysical plasmas were described. The new method of plasma polarization spectroscopy was outlined. There was also a spectroscopic study of particle transport in JT-60U, new results for detached plasmas, and a sketch of the first hot plasma experiments with the Large Helical Device recently completed at NIFS. The 63 of the presented papers are indexed individually. (J.P.N.)

  8. Cold atoms close to surfaces

    DEFF Research Database (Denmark)

    Krüger, Peter; Wildermuth, Stephan; Hofferberth, Sebastian

    2005-01-01

    Microscopic atom optical devices integrated on atom chips allow to precisely control and manipulate ultra-cold (T atoms and Bose-Einstein condensates (BECs) close to surfaces. The relevant energy scale of a BEC is extremely small (down to ... be utilized as a sensor for variations of the potential energy of the atoms close to the surface. Here we describe how to use trapped atoms as a measurement device and analyze the performance and flexibility of the field sensor. We demonstrate microscopic magnetic imaging with simultaneous high spatial...

  9. Topics in atomic collision theory

    CERN Document Server

    Geltman, Sydney; Brueckner, Keith A

    1969-01-01

    Topics in Atomic Collision Theory originated in a course of graduate lectures given at the University of Colorado and at University College in London. It is recommended for students in physics and related fields who are interested in the application of quantum scattering theory to low-energy atomic collision phenomena. No attention is given to the electromagnetic, nuclear, or elementary particle domains. The book is organized into three parts: static field scattering, electron-atom collisions, and atom-atom collisions. These are in the order of increasing physical complexity and hence necessar

  10. Atom-Driven Permeation of Deuterium Through Nb

    Science.gov (United States)

    Ohkoshi, K.; Tohda, S.; Shimura, K.; Yamaguchi, K.; Terai, T.; Yamawaki, M.

    In order to investigate the difference of the hydrogen transport behavior of IDP (ion-driven permeation, i.e. permeation under impingement of the energetic hydrogen ion beam) and ADP (atom-driven permeation, i.e. permeation under exposure of thermal atom beam), an ADP experiment through Nb (niobium) was performed. The dependence of the ADP flux on the specimen temperature turned out to be different from the IDP, where the maximum was observed in the temperature range of 500--1000 K. Such a case has not been seen in the IDP or GDP (gas-driven permeation) case. The deuterium concentration at the downstream-side end bulk volume was estimated employing the phenomenological recombination rate coefficient. Computer calculation showed that the profile of the deuterium concentration becomes almost “flat” under the experimental conditions. Though the experiment'was performed under UHV conditions, the assumption of Sieverts' law-like relation between P*U (virtual pressure of atomic gas, or pressure equivalent to “atomic flow” in the upstream-side vacuum in terms of the molecular flow theory), bulk concentration and PD (pressure of permeated molecules) explains well the strange temperature dependence of the permeation plot.

  11. The Rydberg constant and proton size from atomic hydrogen

    Science.gov (United States)

    Beyer, Axel; Maisenbacher, Lothar; Matveev, Arthur; Pohl, Randolf; Khabarova, Ksenia; Grinin, Alexey; Lamour, Tobias; Yost, Dylan C.; Hänsch, Theodor W.; Kolachevsky, Nikolai; Udem, Thomas

    2017-10-01

    At the core of the “proton radius puzzle” is a four–standard deviation discrepancy between the proton root-mean-square charge radii (rp) determined from the regular hydrogen (H) and the muonic hydrogen (µp) atoms. Using a cryogenic beam of H atoms, we measured the 2S-4P transition frequency in H, yielding the values of the Rydberg constant R∞ = 10973731.568076(96) per meterand rp = 0.8335(95) femtometer. Our rp value is 3.3 combined standard deviations smaller than the previous H world data, but in good agreement with the µp value. We motivate an asymmetric fit function, which eliminates line shifts from quantum interference of neighboring atomic resonances.

  12. Simplifying Electron Beam Channeling in Scanning Transmission Electron Microscopy (STEM).

    Science.gov (United States)

    Wu, Ryan J; Mittal, Anudha; Odlyzko, Michael L; Mkhoyan, K Andre

    2017-08-01

    Sub-angstrom scanning transmission electron microscopy (STEM) allows quantitative column-by-column analysis of crystalline specimens via annular dark-field images. The intensity of electrons scattered from a particular location in an atomic column depends on the intensity of the electron probe at that location. Electron beam channeling causes oscillations in the STEM probe intensity during specimen propagation, which leads to differences in the beam intensity incident at different depths. Understanding the parameters that control this complex behavior is critical for interpreting experimental STEM results. In this work, theoretical analysis of the STEM probe intensity reveals that intensity oscillations during specimen propagation are regulated by changes in the beam's angular distribution. Three distinct regimes of channeling behavior are observed: the high-atomic-number (Z) regime, in which atomic scattering leads to significant angular redistribution of the beam; the low-Z regime, in which the probe's initial angular distribution controls intensity oscillations; and the intermediate-Z regime, in which the behavior is mixed. These contrasting regimes are shown to exist for a wide range of probe parameters. These results provide a new understanding of the occurrence and consequences of channeling phenomena and conditions under which their influence is strengthened or weakened by characteristics of the electron probe and sample.

  13. Leda Beam Diagnostics Instrumentation Beam Position Monitors

    CERN Document Server

    Barr, D

    2000-01-01

    The Low Energy Demonstration Accelerator (LEDA) facility located at Los Alamos National Laboratory (LANL) accelerates protons to an energy of 6.7-MeV and current of 100-mA operating in either a pulsed or cw mode. Of key importance to the commissioning and operations effort is the Beam Position Monitor system (BPM). The LEDA BPM system uses five micro-stripline beam position monitors processed by log ratio processing electronics with data acquisition via a series of custom TMS32OC40 Digital Signal Processing (DSP) boards. Of special interest to this paper is the operation of the system, the log ratio processing, and the system calibration technique. This paper will also cover the DSP system operations and their interaction with the main accelerator control system.

  14. Laser Cooling, Trapping, and Bose-Einstein Condensation of Atoms and Molecules

    Science.gov (United States)

    Leduc, Michèle; Dugué, Julien; Simonet, Juliette

    2009-04-01

    In this paper we first focus on the methods developed to control the position and the velocity of atoms, taking advantage of the radiative forces exerted on atoms placed in a laser beam. Temperatures in the range of μK can be reached for dilute atomic clouds trapped under vacuum in a very small region of space. The application to fountain clocks based on cold cesium atoms is presented. We then describe the characterization and the main features of Bose-Einstein condensates, a new state of matter of purely quantum origin, which can be obtained by subsequent evaporative cooling. The methods in use for cooling molecules are considered, in particular the collision processes or the photoassociation of cold atoms. The possibility of changing interactions between ultracold particles is also explained and photoassociation is illustrated by the recent experiments of our group dealing with metastable helium atoms.

  15. Generalized beam quality factor of aberrated truncated Gaussian laser beams

    CSIR Research Space (South Africa)

    Mafusire, C

    2011-07-01

    Full Text Available The authors outline a theory for the calculation of the beam quality factor of an aberrated laser beam. They provide closed form equations that show that the beam quality factor of an aberrated Gaussian beam depends on all primary aberrations except...

  16. Single kick approximations for beam-beam deflections

    Directory of Open Access Journals (Sweden)

    Takahiko Koyama

    1999-02-01

    Full Text Available A six-dimensional symplectic beam-beam interaction map using finite discrete slices of a strong beam is extended to infinitesimal slices. The new map is calculated under the assumption of a longitudinal Gaussian distribution with approximations. A round Gaussian beam is simulated to demonstrate accuracies of the approximations.

  17. Active SU(1,1) atom interferometry

    Science.gov (United States)

    Linnemann, D.; Schulz, J.; Muessel, W.; Kunkel, P.; Prüfer, M.; Frölian, A.; Strobel, H.; Oberthaler, M. K.

    2017-12-01

    Active interferometers use amplifying elements for beam splitting and recombination. We experimentally implement such a device by using spin exchange in a Bose-Einstein condensate. The two interferometry modes are initially empty spin states that get spontaneously populated in the process of parametric amplification. This nonlinear mechanism scatters atoms into both modes in a pairwise fashion and generates a non-classical state. Finally, a matched second period of spin exchange is performed that nonlinearly amplifies the output signal and maps the phase onto readily detectable first moments. Depending on the accumulated phase this nonlinear readout can reverse the initial dynamics and deamplify the entangled state back to empty spin states. This sequence is described in the framework of SU(1,1) mode transformations and compared to the SU(2) angular momentum description of passive interferometers.

  18. Cavity QED with atomic mirrors

    Science.gov (United States)

    Chang, D. E.; Jiang, L.; Gorshkov, A. V.; Kimble, H. J.

    2012-06-01

    A promising approach to merge atomic systems with scalable photonics has emerged recently, which consists of trapping cold atoms near tapered nanofibers. Here, we describe a novel technique to achieve strong, coherent coupling between a single atom and photon in such a system. Our approach makes use of collective enhancement effects, which allow a lattice of atoms to form a high-finesse cavity within the fiber. We show that a specially designated ‘impurity’ atom within the cavity can experience strongly enhanced interactions with single photons in the fiber. Under realistic conditions, a ‘strong coupling’ regime can be reached, wherein it becomes feasible to observe vacuum Rabi oscillations between the excited impurity atom and a single cavity quantum. This technique can form the basis for a scalable quantum information network using atom-nanofiber systems.

  19. Atomic mechanics of solids

    CERN Document Server

    MacPherson, A K

    1990-01-01

    This volume brings together some of the presently available theoretical techniques which will be useful in the design of solid-state materials. At present, it is impossible to specify the atomic composition of a material and its macroscopic physical properties. However, the future possibilities for such a science are being laid today. This is coming about due to the development of fast, cheap computers which will be able to undertake the calculations which are necessary.Since this field of science is fairly new, it is not yet quite clear which direction of analysis will eventually prov

  20. Electroless atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, David Bruce; Cappillino, Patrick J.; Sheridan, Leah B.; Stickney, John L.; Benson, David M.

    2017-10-31

    A method of electroless atomic layer deposition is described. The method electrolessly generates a layer of sacrificial material on a surface of a first material. The method adds doses of a solution of a second material to the substrate. The method performs a galvanic exchange reaction to oxidize away the layer of the sacrificial material and deposit a layer of the second material on the surface of the first material. The method can be repeated for a plurality of iterations in order to deposit a desired thickness of the second material on the surface of the first material.