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Sample records for eficient atomic frequency

  1. Atomic frequency-time-length standards

    International Nuclear Information System (INIS)

    Gheorghiu, O.C.; Mandache, C.

    1987-01-01

    The principles of operative of atomic frequency-time-length standards and their principle characteristics are described. The role of quartz crystal oscillators which are sloved to active or passive standards is presented. (authors)

  2. Improvement of Frequency Locking Algorithm for Atomic Frequency Standards

    Science.gov (United States)

    Park, Young-Ho; Kang, Hoonsoo; Heyong Lee, Soo; Eon Park, Sang; Lee, Jong Koo; Lee, Ho Seong; Kwon, Taeg Yong

    2010-09-01

    The authors describe a novel method of frequency locking algorithm for atomic frequency standards. The new algorithm for locking the microwave frequency to the Ramsey resonance is compared with the old one that had been employed in the cesium atomic beam frequency standards such as NIST-7 and KRISS-1. Numerical simulations for testing the performance of the algorithm show that the new method has a noise filtering performance superior to the old one by a factor of 1.2 for the flicker signal noise and 1.4 for random-walk signal noise. The new algorithm can readily be used to enhance the frequency stability for a digital servo employing the slow square wave frequency modulation.

  3. Direct Frequency Comb Spectroscopy of Alkali Atoms

    Science.gov (United States)

    Pradhananga, Trinity; Palm, Christopher; Nguyen, Khoa; Guttikonda, Srikanth; Kimball, Derek Jackson

    2011-11-01

    We are using direct frequency comb spectroscopy to study transition frequencies and excited state hyperfine structure in potassium and rubidium using 2-photon transitions excited directly with the frequency-doubled output of a erbium fiber optical frequency comb. The frequency comb output is directed in two counterpropagating directions through a vapor cell containing the atomic vapor of interest. A pair of optical filters is used to select teeth of the comb in order to identify the transition wavelengths. A photomultiplier tube (PMT) measures fluorescence from a decay channel wavelength selected with another optical filter. Using different combinations of filters enables a wide range of transitions to be investigated. By scanning the repetition rate, a Doppler-free spectrum can be obtained enabling kHz-resolution spectral measurements. The thermal motion of the atoms in the vapor cell actually eliminates the need to fine-tune the offset frequency and repetition rate, alleviating a somewhat challenging requirement for spectroscopy of cold atoms. Our investigations are laying the groundwork for a long-term research program to use direct frequency comb spectroscopy to understand the complex spectra of rare-earth atoms.

  4. Investigations of Laser Pumped Gas Cell Atomic Frequency Standard

    National Research Council Canada - National Science Library

    Volk, C. H; Camparo, J. C; Frueholz, R. P

    1981-01-01

    Recently it has been suggested that the performance characteristics of a rubidium gas cell atomic frequency standard might be improved by replacing the standard rubidium discharge lamp with a single mode laser diode...

  5. High-frequency multimodal atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Adrian P. Nievergelt

    2014-12-01

    Full Text Available Multifrequency atomic force microscopy imaging has been recently demonstrated as a powerful technique for quickly obtaining information about the mechanical properties of a sample. Combining this development with recent gains in imaging speed through small cantilevers holds the promise of a convenient, high-speed method for obtaining nanoscale topography as well as mechanical properties. Nevertheless, instrument bandwidth limitations on cantilever excitation and readout have restricted the ability of multifrequency techniques to fully benefit from small cantilevers. We present an approach for cantilever excitation and deflection readout with a bandwidth of 20 MHz, enabling multifrequency techniques extended beyond 2 MHz for obtaining materials contrast in liquid and air, as well as soft imaging of delicate biological samples.

  6. Initial atomic coherences and Ramsey frequency pulling in fountain clocks

    Science.gov (United States)

    Gerginov, Vladislav; Nemitz, Nils; Weyers, Stefan

    2014-09-01

    In the uncertainty budget of primary atomic cesium fountain clocks, evaluations of frequency-pulling shifts of the hyperfine clock transition caused by unintentional excitation of its nearby transitions (Rabi and Ramsey pulling) have been based so far on an approach developed for cesium beam clocks. We re-evaluate this type of frequency pulling in fountain clocks and pay particular attention to the effect of initial coherent atomic states. We find significantly enhanced frequency shifts caused by Ramsey pulling due to sublevel population imbalance and corresponding coherences within the state-selected hyperfine component of the initial atom ground state. Such shifts are experimentally investigated in an atomic fountain clock and quantitative agreement with the predictions of the model is demonstrated.

  7. Resonant difference-frequency atomic force ultrasonic microscope

    Science.gov (United States)

    Cantrell, John H. (Inventor); Cantrell, Sean A. (Inventor)

    2010-01-01

    A scanning probe microscope and methodology called resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM), employs an ultrasonic wave launched from the bottom of a sample while the cantilever of an atomic force microscope, driven at a frequency differing from the ultrasonic frequency by one of the contact resonance frequencies of the cantilever, engages the sample top surface. The nonlinear mixing of the oscillating cantilever and the ultrasonic wave in the region defined by the cantilever tip-sample surface interaction force generates difference-frequency oscillations at the cantilever contact resonance. The resonance-enhanced difference-frequency signals are used to create images of nanoscale near-surface and subsurface features.

  8. Component-Level Demonstration of a Microfabricated Atomic Frequency Reference

    Science.gov (United States)

    2005-08-01

    Kitching, L. A. Liew, and J. Moreland, "A microfabricated atomic clock," Applied Physics Letters, vol. 85, pp. 1460-1462, 2004. [4] R. Lutwak , P...Symposium on Frequency Standards and Metrology, P. Gill, Ed. St. Andrews, Scotland: World Scientific, 2001, pp. 155-166. [31] R. Lutwak , D. Emmons...Frequency and Time Forum. Tampa, FL, 2003, pp. 31-32. [71] R. Lutwak , D. Emmons, T. English, W. Riley, A. Duwel, M. Varghese, D. K. Serkland, and

  9. Portable atomic frequency standard based on coherent population trapping

    Science.gov (United States)

    Shi, Fan; Yang, Renfu; Nian, Feng; Zhang, Zhenwei; Cui, Yongshun; Zhao, Huan; Wang, Nuanrang; Feng, Keming

    2015-05-01

    In this work, a portable atomic frequency standard based on coherent population trapping is designed and demonstrated. To achieve a portable prototype, in the system, a single transverse mode 795nm VCSEL modulated by a 3.4GHz RF source is used as a pump laser which generates coherent light fields. The pump beams pass through a vapor cell containing atom gas and buffer gas. This vapor cell is surrounded by a magnetic shield and placed inside a solenoid which applies a longitudinal magnetic field to lift the Zeeman energy levels' degeneracy and to separate the resonance signal, which has no first-order magnetic field dependence, from the field-dependent resonances. The electrical control system comprises two control loops. The first one locks the laser wavelength to the minimum of the absorption spectrum; the second one locks the modulation frequency and output standard frequency. Furthermore, we designed the micro physical package and realized the locking of a coherent population trapping atomic frequency standard portable prototype successfully. The short-term frequency stability of the whole system is measured to be 6×10-11 for averaging times of 1s, and reaches 5×10-12 at an averaging time of 1000s.

  10. Electromagnetic induction imaging with a radio-frequency atomic magnetometer

    Energy Technology Data Exchange (ETDEWEB)

    Deans, Cameron; Marmugi, Luca, E-mail: l.marmugi@ucl.ac.uk; Hussain, Sarah; Renzoni, Ferruccio [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2016-03-07

    We report on a compact, tunable, and scalable to large arrays imaging device, based on a radio-frequency optically pumped atomic magnetometer operating in magnetic induction tomography modality. Imaging of conductive objects is performed at room temperature, in an unshielded environment and without background subtraction. Conductivity maps of target objects exhibit not only excellent performance in terms of shape reconstruction but also demonstrate detection of sub-millimetric cracks and penetration of conductive barriers. The results presented here demonstrate the potential of a future generation of imaging instruments, which combine magnetic induction tomography and the unmatched performance of atomic magnetometers.

  11. Frequency modulation detection atomic force microscopy in the liquid environment

    Science.gov (United States)

    Jarvis, S. P.; Ishida, T.; Uchihashi, T.; Nakayama, Y.; Tokumoto, H.

    True atomic resolution imaging using frequency modulation detection is already well established in ultra-high vacuum. In this paper we demonstrate that it also has great potential in the liquid environment. Using a combination of magnetic activation and high-aspect-ratio carbon nanotube probes, we show that imaging can be readily combined with point spectroscopy, revealing both the tip-sample interaction and the structure of the intermediate liquid.

  12. Eficiência do uso da água pelo meloeiro sob diferentes freqüências de irrigação Water use efficiency of the melon crop under different irrigation frequencies

    Directory of Open Access Journals (Sweden)

    Valdemício Ferreira de Sousa

    2000-01-01

    Full Text Available Objetivou-se, com este estudo, avaliar o efeito de cinco freqüências de irrigação por gotejamento, na maximização da produtividade e na eficiência do uso da água pelo meloeiro cultivado em solo arenoso de Tabuleiro Costeiro do Piauí. O experimento foi conduzido no Campo Experimental da Embrapa Meio-Norte, localizado no município de Parnaíba, PI, latitude 3º5'S longitude 41º47'W e altitude de 46,8 m. O delineamento experimental foi o de blocos ao acaso, com cinco tratamentos e seis repetições, em que os tratamentos foram: freqüências de irrigação de 0,50, 1,0, 2,0, 3,0 e 4,0 dias. Foram avaliadas as produtividades comercial e total e a eficiência do uso de água, constatando-se que a maior produtividade total (77.985 kg ha-1 e a máxima eficiência do uso da água (EUAEt pelo meloeiro (282,83 kg ha-1 mm-1 são obtidas com freqüência de irrigação de um dia. As freqüências de irrigação de 3 e 4 dias, ou superiores, não são recomendadas para o meloeiro e, se a água é escassa, utilizam-se irrigações com freqüência diária.The objective of this work was to evaluate the effect of five trickle irrigation frequencies to obtain high yields and maximum water use efficiency in a melon crop cultivated in sandy soil of the Coastal Tablelands of Piauí, Brazil. The experiment was carried out in an experimental area of Embrapa Meio-Norte in Parnaíba, Piauí State, Brazil, latitude 3º5' S, longitude 41º47' W and altitude 46.8 m. A randomized block with five treatments and six replications was used, with irrigation frequencies of 0.5, 1.0, 2.0, 3.0 and 4.0 days. The total and commercial yield and water use efficiency were evaluated. The highest total yield (77.985 kg ha-1 and the maximum water use efficiency by melon crop (282.83 kg ha-1 mm-1 were obtained with an irrigation frequency of one day. The irrigation frequencies of 3 and 4 days or higher are not recommended for the melon crop, and if the water is scarce an

  13. Atomic Oxygen Energy in Low Frequency Hyperthermal Plasma Ashers

    Science.gov (United States)

    Banks, Bruce A.; Miller, Sharon K R.; Kneubel, Christian A.

    2014-01-01

    Experimental and analytical analysis of the atomic oxygen erosion of pyrolytic graphite as well as Monte Carlo computational modeling of the erosion of Kapton H (DuPont, Wilmington, DE) polyimide was performed to determine the hyperthermal energy of low frequency (30 to 35 kHz) plasma ashers operating on air. It was concluded that hyperthermal energies in the range of 0.3 to 0.9 eV are produced in the low frequency air plasmas which results in texturing similar to that in low Earth orbit (LEO). Monte Carlo computational modeling also indicated that such low energy directed ions are fully capable of producing the experimentally observed textured surfaces in low frequency plasmas.

  14. Two-photon direct frequency comb spectroscopy of alkali atoms

    Science.gov (United States)

    Palm, Christopher; Pradhananga, Trinity; Nguyen, Khoa; Montcrieffe, Caitlin; Kimball, Derek

    2012-11-01

    We have studied transition frequencies and excited state hyperfine structure in rubidium using 2-photon transitions excited directly with the frequency-doubled output of a erbium fiber optical frequency comb. The frequency comb output is directed in two counterpropagating directions through a vapor cell containing the rubidium vapor. A pair of optical filters is used to select teeth of the comb in order to identify the transition wavelengths. A photomultiplier tube (PMT) measures fluorescence from a decay channel wavelength selected with another optical filter. Using different combinations of filters enables a wide range of transitions to be investigated. By scanning the repetition rate, a Doppler-free spectrum can be obtained enabling kHz-resolution spectral measurements. An interesting dependence of the 2-photon spectrum on the energy of the intermediate state of the 2-photon transition is discussed. Our investigations are laying the groundwork for a long-term research program to use direct frequency comb spectroscopy to understand the complex spectra of rare-earth atoms.

  15. The Brazilian time and frequency atomic standards program

    Directory of Open Access Journals (Sweden)

    Mushtaq Ahmed

    2008-06-01

    Full Text Available Cesium atomic beam clocks have been the workhorse for many demanding applications in science and technology for the past four decades. Tests of the fundamental laws of physics and the search for minute changes in fundamental constants, the synchronization of telecommunication networks, and realization of the satellite-based global positioning system would not be possible without atomic clocks. The adoption of optical cooling and trapping techniques, has produced a major advance in atomic clock precision. Cold-atom fountain and compact cold-atom clocks have also been developed. Measurement precision of a few parts in 10(15 has been demonstrated for a cold-atom fountain clock. We present here an overview of the time and frequency metrology program based on cesium atoms under development at USP São Carlos. This activity consists of construction and characterization of atomic-beam, and several variations of cold-atom clocks. We discuss the basic working principles, construction, evaluation, and important applications of atomic clocks in the Brazilian program.Relógios atômicos de feixe de Césio têm sido a base para diversas aplicações em ciência e tecnologia nas últimas quatro décadas. Testes de leis fundamentais de física, buscas por mínimas variações em constantes fundamentais, sincronização de redes de telecomunicações e o funcionamento do sistema de posicionamento global, baseado em satélites de navegação, não seriam possíveis sem os relógios atômicos. A adoção de técnicas de aprisionamento e resfriamento ópticos tem permitido um grande avanço na precisão dos relógios atômicos. Chafarizes de átomos frios e relógios compactos de átomos frios também têm sido desenvolvidos. Precisões de medida de algumas partes em 1015 foram demonstradas para relógios do tipo chafariz de átomos frios. Apresentamos uma visão geral do programa de metrologia de tempo e freqüência baseado em átomos de césio, em

  16. Autopilot for frequency-modulation atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kuchuk, Kfir; Schlesinger, Itai; Sivan, Uri, E-mail: phsivan@tx.technion.ac.il [Department of Physics and the Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa 32000 (Israel)

    2015-10-15

    One of the most challenging aspects of operating an atomic force microscope (AFM) is finding optimal feedback parameters. This statement applies particularly to frequency-modulation AFM (FM-AFM), which utilizes three feedback loops to control the cantilever excitation amplitude, cantilever excitation frequency, and z-piezo extension. These loops are regulated by a set of feedback parameters, tuned by the user to optimize stability, sensitivity, and noise in the imaging process. Optimization of these parameters is difficult due to the coupling between the frequency and z-piezo feedback loops by the non-linear tip-sample interaction. Four proportional-integral (PI) parameters and two lock-in parameters regulating these loops require simultaneous optimization in the presence of a varying unknown tip-sample coupling. Presently, this optimization is done manually in a tedious process of trial and error. Here, we report on the development and implementation of an algorithm that computes the control parameters automatically. The algorithm reads the unperturbed cantilever resonance frequency, its quality factor, and the z-piezo driving signal power spectral density. It analyzes the poles and zeros of the total closed loop transfer function, extracts the unknown tip-sample transfer function, and finds four PI parameters and two lock-in parameters for the frequency and z-piezo control loops that optimize the bandwidth and step response of the total system. Implementation of the algorithm in a home-built AFM shows that the calculated parameters are consistently excellent and rarely require further tweaking by the user. The new algorithm saves the precious time of experienced users, facilitates utilization of FM-AFM by casual users, and removes the main hurdle on the way to fully automated FM-AFM.

  17. Autopilot for frequency-modulation atomic force microscopy.

    Science.gov (United States)

    Kuchuk, Kfir; Schlesinger, Itai; Sivan, Uri

    2015-10-01

    One of the most challenging aspects of operating an atomic force microscope (AFM) is finding optimal feedback parameters. This statement applies particularly to frequency-modulation AFM (FM-AFM), which utilizes three feedback loops to control the cantilever excitation amplitude, cantilever excitation frequency, and z-piezo extension. These loops are regulated by a set of feedback parameters, tuned by the user to optimize stability, sensitivity, and noise in the imaging process. Optimization of these parameters is difficult due to the coupling between the frequency and z-piezo feedback loops by the non-linear tip-sample interaction. Four proportional-integral (PI) parameters and two lock-in parameters regulating these loops require simultaneous optimization in the presence of a varying unknown tip-sample coupling. Presently, this optimization is done manually in a tedious process of trial and error. Here, we report on the development and implementation of an algorithm that computes the control parameters automatically. The algorithm reads the unperturbed cantilever resonance frequency, its quality factor, and the z-piezo driving signal power spectral density. It analyzes the poles and zeros of the total closed loop transfer function, extracts the unknown tip-sample transfer function, and finds four PI parameters and two lock-in parameters for the frequency and z-piezo control loops that optimize the bandwidth and step response of the total system. Implementation of the algorithm in a home-built AFM shows that the calculated parameters are consistently excellent and rarely require further tweaking by the user. The new algorithm saves the precious time of experienced users, facilitates utilization of FM-AFM by casual users, and removes the main hurdle on the way to fully automated FM-AFM.

  18. Influence of driving frequency on oxygen atom density in O2 radio frequency capacitively coupled plasma

    International Nuclear Information System (INIS)

    Kitajima, Takeshi; Noro, Kouichi; Nakano, Toshiki; Makabe, Toshiaki

    2004-01-01

    The influence of the driving frequency on the absolute oxygen atom density in an O 2 radio frequency (RF) capacitively coupled plasma (CCP) was investigated using vacuum ultraviolet absorption spectroscopy with pulse modulation of the main plasma. A low-power operation of a compact inductively coupled plasma light source was enabled to avoid the significant measurement errors caused by self-absorption in the light source. The pulse modulation of the main plasma enabled accurate absorption measurement for high plasma density conditions by eliminating background signals due to light emission from the main plasma. As for the effects of the driving frequency, the effect of VHF (100 MHz) drive on oxygen atom production was small because of the modest increase in plasma density of electronegative O 2 in contrast to the significant increase in electron density previously observed for electropositive Ar. The recombination coefficient of oxygen atoms on the electrode surface was obtained from a decay rate in the afterglow by comparison with a diffusion model, and it showed agreement with previously reported values for several electrode materials

  19. Increased somatic cell mutant frequency in atomic bomb survivors

    International Nuclear Information System (INIS)

    Hakoda, Masayuki; Akiyama, Mitoshi; Kyoizumi, Seishi; Awa, A.A.; Yamakido, Michio; Otake, Masanori.

    1988-05-01

    Frequencies of mutant T-cells in peripheral blood, which are deficient in the activity of hypoxanthine guanine phosphoribosyltransferase (HPRT) were determined for atomic bomb survivors by direct clonal assay using a previously reported method. Results from 30 exposed survivors (exposed to more than 1 rad) and 17 age- and sex-matched controls (exposed to less than 1 rad) were analyzed. The mean mutant frequency (Mf) in the exposed (5.2 x 10 -6 ; range 0.8 - 14.4 x 10 -6 ) was significantly higher than in controls (3.4 x 10 -6 ; range 1.3 - 9.3 x 10 -6 ), a fact not attributable to lower nonmutant cell cloning efficiencies in the exposed group since cell cloning efficiencies were virtually identical in both groups. An initial analysis of the data did not reveal a significant correlation between individual Mfs and individual radiation dose estimates when the latter were defined by the original, tentative estimates (T65D), even though there was a significant positive correlation of Mfs with individual frequency of lymphocytes bearing chromosome aberration. However, reanalysis using the newer revised individual dose estimates (DS86) for 27 exposed survivors and 17 controls did reveal a significant but shallow positive correlation between T-cell Mf values and individual exposure doses. These results indicate that HPRT mutation in vivo in human T-cells could be detected in these survivors 40 years after the presumed mutational event. (author)

  20. Mercury Atomic Frequency Standards for Space Based Navigation and Timekeeping

    Science.gov (United States)

    Tjoelker, R. L.; Burt, E. A.; Chung, S.; Hamell, R. L.; Prestage, J. D.; Tucker, B.; Cash, P.; Lutwak, R.

    2012-01-01

    A low power Mercury Atomic Frequency Standard (MAFS) has been developed and demonstrated on the path towards future space clock applications. A self contained mercury ion breadboard clock: emulating flight clock interfaces, steering a USO local oscillator, and consuming approx 40 Watts has been operating at JPL for more than a year. This complete, modular ion clock instrument demonstrates that key GNSS size, weight, and power (SWaP) requirements can be achieved while still maintaining short and long term performance demonstrated in previous ground ion clocks. The MAFS breadboard serves as a flexible platform for optimizing further space clock development and guides engineering model design trades towards fabrication of an ion clock for space flight.

  1. Polarization effects in two-colour ionization of atomic hydrogen with incommensurable frequencies

    International Nuclear Information System (INIS)

    Cionga, A.

    1993-01-01

    The angular distribution of ejected electrons for two-colour ionization of atomic hydrogen are studied using an approach which takes into account the radiative corrections to both bound and the continuum states. One considers the ionization process in which one high-frequency photon has enough energy to ionize the atom, meanwhile, one extra-photon is exchanged between atomic system and the low-frequency field. We focus our attention to the case of two incommensurable frequencies. (Author)

  2. Techniques for measuring the atomic recoil frequency using a grating-echo atom interferometer

    Science.gov (United States)

    Barrett, Brynle

    I have developed three types of time-domain echo atom interferometer (AIs) that use either two or three standing-wave pulses in different configurations. Experiments approaching the transit time limit are achieved using samples of laser-cooled rubidium atoms with temperatures AI. This interferometer uses two standing-wave pulses applied at times t = 0 and t = T 21 to create a superposition of atomic momentum states differing by multiples of the two-photon momentum, ħq = 2 ħk where k is the optical wave number, that interfere in the vicinity of t = 2T 21. This interference or "echo" manifests itself as a density grating in the atomic sample, and is probed by applying a near-resonant traveling-wave "read-out" pulse and measuring the intensity of the coherent light Bragg-scattered in the backward direction. The scattered light from the grating is associated with a λ/2-periodic modulation produced by the interference of momentum states differing by ħq. Interfering states that differ by more than ħq—which produce higher-frequency spatial modulation within the sample—cannot be detected due to the nature of the Bragg scattering detection technique employed in the experiment. The intensity of the scattered light varies in a periodic manner as a function of the standing-wave pulse separation, T21. The fundamental frequency of this modulation is the two-photon atomic recoil frequency, ω q = ħq2/2M, where q = 2k and M is the mass of the atom (a rubidium isotope in this case). The recoil frequency, ω q, is related to the recoil energy, Eq = ħωq, which is the kinetic energy associated with the recoil of the atom after a coherent two-photon scattering process. By performing the experiment on a suitably long time scale ( T21 >> τq = π/ω q ˜32 μs), ωq can be measured precisely. Since ωq contains the ratio of Planck's constant to the mass of the atom, h/M, a precise measurement of ωq can be used as a strict test of quantum theories of the electromagnetic force

  3. Radio frequency selective addressing of localized atoms in a periodic potential

    International Nuclear Information System (INIS)

    Ott, H.; De Mirandes, E.; Ferlaino, F.; Roati, G.; Tuerck, V.; Modugno, G.; Inguscio, M.

    2004-01-01

    We study the localization and addressability of ultracold atoms in a combined parabolic and periodic potential. Such a potential supports the existence of localized stationary states and we show that applying a radio frequency field allows us to selectively address atoms in these states. This method is used to measure the energy and momentum distribution of the atoms in the localized states. We also discuss possible extensions of this scheme to address and manipulate atoms in single lattice sites

  4. Frequency shifts in spontaneous emission from two interacting atoms

    International Nuclear Information System (INIS)

    James, D.F.V.

    1993-01-01

    A model radiating system consisting of two atoms in close proximity is analyzed. This system demonstrates the influence of spatial coherence on the spectrum of the radiation field. Explicit expressions for the degree of coherence, the source spectrum, and the spectrum of the radiation field are derived. The results are discussed in terms of Wolf's work [Phys. Rev. Lett. 56, 1370 (1986)] on this effect, which can be considered in terms of a multiple-atom analog of the effects of radiation reaction on a single atom, i.e., spontaneous decay and the Lamb shift

  5. Extremely short pulses via stark modulation of the atomic transition frequencies.

    Science.gov (United States)

    Radeonychev, Y V; Polovinkin, V A; Kocharovskaya, Olga

    2010-10-29

    We propose a universal method to produce extremely short pulses of electromagnetic radiation in various spectral ranges. The essence of the method is a resonant interaction of radiation with atoms under the conditions of adiabatic periodic modulation of atomic transition frequencies by a far-off-resonant control laser field via dynamic Stark shift of the atomic levels and proper adjustment of the control field intensity and frequency, as well as the optical depth of the medium. The potential of the method is illustrated by an example in a hydrogenlike atomic system.

  6. Compact, Low-Power Atomic Time and Frequency Standards

    Science.gov (United States)

    2008-12-01

    2007). This is consistent with other reports of survival of CSAC devices with thin polymide tethers to 500g ( Lutwak et al., 2007). • Humidity...InterPACK 󈧋 , July 8-12, 2007, Vancouver, British Columbia, CANADA Lutwak , R., et al., “The chip-scale atomic clock – prototype evaluation

  7. Rydberg-atom based radio-frequency electrometry using frequency modulation spectroscopy in room temperature vapor cells.

    Science.gov (United States)

    Kumar, Santosh; Fan, Haoquan; Kübler, Harald; Jahangiri, Akbar J; Shaffer, James P

    2017-04-17

    Rydberg atom-based electrometry enables traceable electric field measurements with high sensitivity over a large frequency range, from gigahertz to terahertz. Such measurements are particularly useful for the calibration of radio frequency and terahertz devices, as well as other applications like near field imaging of electric fields. We utilize frequency modulated spectroscopy with active control of residual amplitude modulation to improve the signal to noise ratio of the optical readout of Rydberg atom-based radio frequency electrometry. Matched filtering of the signal is also implemented. Although we have reached similarly, high sensitivity with other read-out methods, frequency modulated spectroscopy is advantageous because it is well-suited for building a compact, portable sensor. In the current experiment, ∼3 µV cm-1 Hz-1/2 sensitivity is achieved and is found to be photon shot noise limited.

  8. Deterministically swapping frequency-bin entanglement from photon-photon to atom-photon hybrid systems

    Science.gov (United States)

    Ou, Bao-Quan; Liu, Chang; Sun, Yuan; Chen, Ping-Xing

    2018-02-01

    Inspired by the recent developments of the research on the atom-photon quantum interface and energy-time entanglement between single-photon pulses, we are motivated to study the deterministic protocol for the frequency-bin entanglement of the atom-photon hybrid system, which is analogous to the frequency-bin entanglement between single-photon pulses. We show that such entanglement arises naturally in considering the interaction between a frequency-bin entangled single-photon pulse pair and a single atom coupled to an optical cavity, via straightforward atom-photon phase gate operations. Its anticipated properties and preliminary examples of its potential application in quantum networking are also demonstrated. Moreover, we construct a specific quantum entanglement witness tool to detect such extended frequency-bin entanglement from a reasonably general set of separable states, and prove its capability theoretically. We focus on the energy-time considerations throughout the analysis.

  9. Fast phase stabilization of a low frequency beat note for atom interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Oh, E.; Horne, R. A.; Sackett, C. A., E-mail: sackett@virginia.edu [Department of Physics, University of Virginia, 382 McCormick Road, Charlottesville, Virginia 22904-4714 (United States)

    2016-06-15

    Atom interferometry experiments rely on the ability to obtain a stable signal that corresponds to an atomic phase. For interferometers that use laser beams to manipulate the atoms, noise in the lasers can lead to errors in the atomic measurement. In particular, it is often necessary to actively stabilize the optical phase between two frequency components of the beams. Typically this is achieved using a time-domain measurement of a beat note between the two frequencies. This becomes challenging when the frequency difference is small and the phase measurement must be made quickly. The method presented here instead uses a spatial interference detection to rapidly measure the optical phase for arbitrary frequency differences. A feedback system operating at a bandwidth of about 10 MHz could then correct the phase in about 3 μs. This time is short enough that the phase correction could be applied at the start of a laser pulse without appreciably degrading the fidelity of the atom interferometer operation. The phase stabilization system was demonstrated in a simple atom interferometer measurement of the {sup 87}Rb recoil frequency.

  10. Frequency lock of a dye laser emission on iron atomic line top

    International Nuclear Information System (INIS)

    Durand, P.

    1995-03-01

    The aim of this thesis is to realize a frequency lock of a dye laser emission on iron atomic line top. To reach that goal, the author first presents the calculation of atomic vapour density by means of laser absorption ratio measure and studies the dye laser working. It is then necessary to find a device giving the required precision on the frequency of the absorption line choosen. It is obtained thanks to the atomic line reconstitution by optogalvanic effect which gives the reference. Besides, the author presents the necessity of a laser emission power regulation which is obtained thanks to a device including an acoustic and optic modulator. A reliable and accurate captor is choosen and adjusted testing various hollow cathode lamps. The method to obtain the frequency lock of laser emission on iron atomic line top is described. (TEC). 18 refs., 64 figs

  11. Frequency Fine-tuning of a Spin-flip Cavity for Antihydrogen Atoms

    CERN Document Server

    Federmann, S; Mahner, E; Juhasz, B; Widmann, E

    2012-01-01

    As part of the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) physics program a spin-flip cavity, for measurements of the ground-state hyperfine transition frequency of antihydrogen atoms, is needed. The purpose of the cavity is to excite antihydrogen atoms depending on their polarisation by a microwave field operating at 1.42 GHz. The delicacy of designing such a cavity lies in achieving and maintaining the required properties of this field over a large aperture of 10 cm and for a long period of time (required amplitude stability is 1% over 12 h). This paper presents the frequency fine tuning techniques developed to obtain the desired centre frequency of 1.42GHz with a Q value below 500 as well as the circuit used for the frequency sweep over a bandwidth of 6MHz.

  12. Detecting an atomic clock frequency anomaly using an adaptive Kalman filter algorithm

    Science.gov (United States)

    Song, Huijie; Dong, Shaowu; Wu, Wenjun; Jiang, Meng; Wang, Weixiong

    2018-06-01

    The abnormal frequencies of an atomic clock mainly include frequency jump and frequency drift jump. Atomic clock frequency anomaly detection is a key technique in time-keeping. The Kalman filter algorithm, as a linear optimal algorithm, has been widely used in real-time detection for abnormal frequency. In order to obtain an optimal state estimation, the observation model and dynamic model of the Kalman filter algorithm should satisfy Gaussian white noise conditions. The detection performance is degraded if anomalies affect the observation model or dynamic model. The idea of the adaptive Kalman filter algorithm, applied to clock frequency anomaly detection, uses the residuals given by the prediction for building ‘an adaptive factor’ the prediction state covariance matrix is real-time corrected by the adaptive factor. The results show that the model error is reduced and the detection performance is improved. The effectiveness of the algorithm is verified by the frequency jump simulation, the frequency drift jump simulation and the measured data of the atomic clock by using the chi-square test.

  13. Atomic scattering in the presence of a low-frequency laser

    International Nuclear Information System (INIS)

    Banerji, J.

    1982-01-01

    In the first four chapters of this thesis previous work on non-resonant potential scattering, resonant potential scattering and non-resonant electron-atom scattering in the presence of a low-frequency laser has been discussed and extended. Chapter 6 deals with the experimental aspects of laser-modified atomic scattering. In chapter 7, the problem of electron-atom ionizing collisions (both resonant and non-resonant) in the presence of a low-frequency laser is discussed. In the next chapter the cut-off Coulomb potential scattering in the presence of a low-frequency laser has been considered. Because of the long range of the Coulomb potential, the result deviates sharply from that obtained for short range potentials unless, of course, the collision energy is very high. Moreover, it has been suggested that the experiments are not reproducible unless the details of the cut-off Coulomb potential are spelled out

  14. Optical Measurements of Strong Radio-Frequency Fields Using Rydberg Atoms

    Science.gov (United States)

    Miller, Stephanie Anne

    There has recently been an initiative toward establishing atomic measurement standards for field quantities, including radio-frequency, millimeter-wave, and micro-wave electric fields. Current measurement standards are obtained using dipole antennas, which are fundamentally limited in frequency bandwidth (set by the physical size of the antenna) and accuracy (due to the metal perturbing the field during the measurement). Establishing an atomic standard rectifies these problems. My thesis work contributes to an ongoing effort towards establishing the viability of using Rydberg electromagnetically induced transparency (EIT) to perform atom-based measurements of radio-frequency (RF) fields over a wide range of frequencies and field strengths, focusing on strong-field measurements. Rydberg atoms are atoms with an electron excited to a high principal quantum number, resulting in a high sensitivity to an applied field. A model based on Floquet theory is implemented to accurately describe the observed atomic energy level shifts from which information about the field is extracted. Additionally, the effects due to the different electric field domains within the measurement volume are accurately modeled. Absolute atomic measurements of fields up to 296 V/m within a +/-0.35% relative uncertainty are demonstrated. This is the strongest field measured at the time of data publication. Moreover, the uncertainty is over an order of magnitude better than that of current standards. A vacuum chamber setup that I implemented during my graduate studies is presented and its unique components are detailed. In this chamber, cold-atom samples are generated and Rydberg atoms are optically excited within the ground-state sample. The Rydberg ion detection and imaging procedure are discussed, particularly the high magnification that the system provides. By analyzing the position of the ions, the spatial correlation g(2) (r) of Rydberg-atom distributions can be extracted. Aside from ion

  15. FREQUENCY REDISTRIBUTION OF POLARIZED LIGHT IN THE Λ-TYPE MULTI-TERM POLARIZED ATOM

    Energy Technology Data Exchange (ETDEWEB)

    Casini, R. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Sainz, R. Manso [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

    2016-06-20

    We study the effects of Rayleigh and Raman scattering on the formation of polarized spectral lines in a Λ-type multi-term atom. We fully take into account the partial redistribution of frequency and the presence of atomic polarization in the lower states of the atomic model. Problems that can be modeled with this formalism include, for example, the formation of the Ca ii H–K and IR triplet, the analogous system of Ba ii, and the Ly β –H α system of hydrogenic ions.

  16. Low-frequency acoustic atomization with oscillatory flow around micropillars in a microfluidic device

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, Yin Nee, E-mail: mailccheung@gmail.com, E-mail: mtnwong@ntu.edu.sg; Wong, Teck Neng, E-mail: mailccheung@gmail.com, E-mail: mtnwong@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Nguyen, Nam Trung, E-mail: nam-trung.nguyen@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Brisbane QLD 4111 (Australia)

    2014-10-06

    This letter reports a low frequency acoustic atomization technique with oscillatory extensional flow around micropillars. Large droplets passing through two micropillars are elongated. Small droplets are then produced through the pinch-off process at the spindle-shape ends. As the actuation frequency increases, the droplet size decreases with increasing monodispersity. This method is suitable for in-situ mass production of fine droplets in a multi-phase environment without external pumping. Small particles encapsulation was demonstrated with the current technique.

  17. Does an atom interferometer test the gravitational redshift at the Compton frequency?

    International Nuclear Information System (INIS)

    Wolf, Peter; Borde, Christian J; Blanchet, Luc; Reynaud, Serge; Salomon, Christophe; Cohen-Tannoudji, Claude

    2011-01-01

    Atom interferometers allow the measurement of the acceleration of freely falling atoms with respect to an experimental platform at rest on Earth's surface. Such experiments have been used to test the universality of free fall by comparing the acceleration of the atoms to that of a classical freely falling object. In a recent paper, Mueller et al (2010 Nature 463 926-9) argued that atom interferometers also provide a very accurate test of the gravitational redshift (or universality of clock rates). Considering the atom as a clock operating at the Compton frequency associated with the rest mass, they claimed that the interferometer measures the gravitational redshift between the atom-clocks in the two paths of the interferometer at different values of gravitational potentials. In this paper, we analyze this claim in the frame of general relativity and of different alternative theories. We show that the difference of 'Compton phases' between the two paths of the interferometer is actually zero in a large class of theories, including general relativity, all metric theories of gravity, most non-metric theories and most theoretical frameworks used to interpret the violations of the equivalence principle. Therefore, in most plausible theoretical frameworks, there is no redshift effect and atom interferometers only test the universality of free fall. We also show that frameworks in which atom interferometers would test the redshift pose serious problems, such as (i) violation of the Schiff conjecture, (ii) violation of the Feynman path integral formulation of quantum mechanics and of the principle of least action for matter waves, (iii) violation of energy conservation, and more generally (iv) violation of the particle-wave duality in quantum mechanics. Standard quantum mechanics is no longer valid in such frameworks, so that a consistent interpretation of the experiment would require an alternative formulation of quantum mechanics. As such an alternative has not been

  18. Rydberg atoms in circular polarization: Classical stabilization in optical frequency fields

    International Nuclear Information System (INIS)

    Chism, Will; Reichl, L.E.

    2002-01-01

    We investigate the classical dynamics of the Rydberg atom in circularly polarized laser fields, restricted to the two-dimensional plane of polarization. We use a Poincare surface of section to study nonlinear resonance structures for optical frequency driving fields. We demonstrate the existence and morphology of these structures as the laser intensity transitions from moderate to intense

  19. Atomic and molecular spectroscopy with optical-frequency-comb-referenced IR coherent sources

    International Nuclear Information System (INIS)

    Cancio, P.; Bartalini, S.; De Rosa, M.; Giusfredi, G.; Mazzotti, D.; Maddaloni, P.; Vitiello, M. S.; De Natale, P.

    2013-01-01

    We provide a review of progress in the development of metrological-grade measurements in atomic and molecular systems through the extension, in the mid-infrared and far-infrared range, of optical frequency combs (OFCs) and the introduction of new techniques and highly coherent sources. (authors)

  20. Note: A versatile radio-frequency source for cold atom experiments

    Energy Technology Data Exchange (ETDEWEB)

    Li, Na; Wu, Yu-Ping; Min, Hao; Yang, Tao; Jiang, Xiao, E-mail: jiangx@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2016-08-15

    A radio-frequency (RF) source designed for cold atom experiments is presented. The source uses AD9858, a direct digital synthesizer, to generate the sine wave directly, up to 400 MHz, with sub-Hz resolution. An amplitude control circuit consisting of wideband variable gain amplifier and high speed digital to analog converter is integrated into the source, capable of 70 dB off isolation and 4 ns on-off keying. A field programmable gate array is used to implement a versatile frequency and amplitude co-sweep logic. Owing to modular design, the RF sources have been used on many cold atom experiments to generate various complicated RF sequences, enriching the operation schemes of cold atoms, which cannot be done by standard RF source instruments.

  1. Manipulation of ultracold atoms in dressed adiabatic radio-frequency potentials

    DEFF Research Database (Denmark)

    Lesanovsky, Igor; Hofferberth, S.; Schmiedmayer, Jörg

    2006-01-01

    We explore properties of atoms whose magnetic hyperfine sublevels are coupled by an external magnetic radio frequency (rf) field. We perform a thorough theoretical analysis of this driven system and present a number of systematic approximations which eventually give rise to dressed adiabatic radio...... frequency potentials. The predictions of this analytical investigation are compared to numerically exact results obtained by a wave packet propagation. We outline the versatility and flexibility of this class of potentials and demonstrate their potential use to build atom optical elements such as double...... wells, interferometers, and ringtraps. Moreover, we perform simulations of interference experiments carried out in rf induced double-well potentials. We discuss how the nature of the atom-field coupling mechanism gives rise to a decrease of the interference contrast....

  2. Black-body radiation effects and light shifts in atomic frequency standards

    Energy Technology Data Exchange (ETDEWEB)

    Pal' chikov, V G; Domnin, Yu S; Novoselov, A V [Institute of Metrology for Time and Space at National Research Institute for Physical-Technical and Radiotechnical Measurements - IMVP GP VNIIFTRI, Mendeleevo, Moscow Region, 141570 (Russian Federation)

    2003-04-01

    A general method is presented for calculating the higher-order terms of series in powers of the black-body radiation field for the Stark-state wavefunctions, dipole transition matrix elements and corresponding frequency shifts of hyperfine splitting in the ground states for Cs and Rb atoms. A numerical method for calculating the light shifts in Sr atoms is described. It is based on the Green function method for summation over all intermediate states and exact Dirac-Fock wavefunctions for the resonant transitions to the first excited s-, p- and d-states. By comparing the calculated Stark shift with results of measurements employing atomic frequency standards, the black-body radiation effects on the ground state are analysed.

  3. Dynamic regime of coherent population trapping and optimization of frequency modulation parameters in atomic clocks.

    Science.gov (United States)

    Yudin, V I; Taichenachev, A V; Basalaev, M Yu; Kovalenko, D V

    2017-02-06

    We theoretically investigate the dynamic regime of coherent population trapping (CPT) in the presence of frequency modulation (FM). We have formulated the criteria for quasi-stationary (adiabatic) and dynamic (non-adiabatic) responses of atomic system driven by this FM. Using the density matrix formalism for Λ system, the error signal is exactly calculated and optimized. It is shown that the optimal FM parameters correspond to the dynamic regime of atomic-field interaction, which significantly differs from conventional description of CPT resonances in the frame of quasi-stationary approach (under small modulation frequency). Obtained theoretical results are in good qualitative agreement with different experiments. Also we have found CPT-analogue of Pound-Driver-Hall regime of frequency stabilization.

  4. Temporal interference with frequency-controllable long photons from independent cold atomic sources

    Science.gov (United States)

    Qian, Peng; Gu, Zhenjie; Wen, Rong; Zhang, Weiping; Chen, J. F.

    2018-01-01

    The interference of single photons from independent sources is an essential tool in quantum information processing. However, the interfering of photons with long temporal states in a time-resolved manner has rarely been studied. This is because without transmitting spectral filters or coupling to a cavity mode single photons generated in traditional nonlinear crystals suffer from a short temporal profile below 1 ns. With spectral correlation maintained in the biphotons generated from spontaneous four-wave mixing process in cold atom clouds, here we demonstrate the temporal interference of two frequency-tunable long photons from two independent cold atomic sources. We observe and analyze the interference of frequency-mismatched photons, where the phenomenon of the quantum beat at megahertz separation is displayed. Our paper provides more details for the quantum beat of two independent narrow-band single photons, which may find potential application in frequency-encoded photonic qubits in quantum information processing.

  5. Propagation of frequency-chirped laser pulses in a medium of atoms with a Λ-level scheme

    International Nuclear Information System (INIS)

    Demeter, G.; Dzsotjan, D.; Djotyan, G. P.

    2007-01-01

    We study the propagation of frequency-chirped laser pulses in optically thick media. We consider a medium of atoms with a Λ level-scheme (Lambda atoms) and also, for comparison, a medium of two-level atoms. Frequency-chirped laser pulses that induce adiabatic population transfer between the atomic levels are considered. They induce transitions between the two lower (metastable) levels of the Λ-atoms and between the ground and excited states of the two-level atoms. We show that associated with this adiabatic population transfer in Λ-atoms, there is a regime of enhanced transparency of the medium--the pulses are distorted much less than in the medium of two-level atoms and retain their ability to transfer the atomic population much longer during propagation

  6. Acoustic Imaging Frequency Dynamics of Ferroelectric Domains by Atomic Force Microscopy

    International Nuclear Information System (INIS)

    Kun-Yu, Zhao; Hua-Rong, Zeng; Hong-Zhang, Song; Sen-Xing, Hui; Guo-Rong, Li; Qing-Rui, Yin; Shimamura, Kiyoshi; Kannan, Chinna Venkadasamy; Villora, Encarnacion Antonia Garcia; Takekawa, Shunji; Kitamura, Kenji

    2008-01-01

    We report the acoustic imaging frequency dynamics of ferroelectric domains by low-frequency acoustic probe microscopy based on the commercial atomic force microscopy It is found that ferroelectric domain could be firstly visualized at lower frequency down to 0.5 kHz by AFM-based acoustic microscopy The frequency-dependent acoustic signal revealed a strong acoustic response in the frequency range from 7kHz to 10kHz, and reached maximum at 8.1kHz. The acoustic contrast mechanism can be ascribed to the different elastic response of ferroelectric microstructures to local elastic stress fields, which is induced by the acoustic wave transmitting in the sample when the piezoelectric transducer is vibrating and exciting acoustic wave under ac electric fields due to normal piezoelectric effects. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  7. Frequency of marriage and live birth among survivors prenatally exposed to the atomic bomb

    International Nuclear Information System (INIS)

    Blot, W.J.; Shimizu, Y.; Kato, H.; Miller, R.W.

    1975-01-01

    Frequency of marriage and birth as of January 1973 was determined for persons exposed in utero to the atomic bombs in 1945 and for controls. The marriage rate was lower in persons heavily exposed in utero than in the non-exposed or lightly exposed. This difference is attributed partly to the lesser marriageability of persons with mental retardation who are significantly more numerous among the heavily exposed, and partly to unmeasured variables, possibly including social discrimination against survivors of the atomic bomb. No consistent relation was observed between radiation exposure and three reproductive indices: childless marriages, number of births, and interval between marriage and first birth

  8. Adiabatic perturbation theory for atoms and molecules in the low-frequency regime.

    Science.gov (United States)

    Martiskainen, Hanna; Moiseyev, Nimrod

    2017-12-14

    There is an increasing interest in the photoinduced dynamics in the low frequency, ω, regime. The multiphoton absorptions by molecules in strong laser fields depend on the polarization of the laser and on the molecular structure. The unique properties of the interaction of atoms and molecules with lasers in the low-frequency regime imply new concepts and directions in strong-field light-matter interactions. Here we represent a perturbational approach for the calculations of the quasi-energy spectrum in the low-frequency regime, which avoids the construction of the Floquet operator with extremely large number of Floquet channels. The zero-order Hamiltonian in our perturbational approach is the adiabatic Hamiltonian where the atoms/molecules are exposed to a dc electric field rather than to ac-field. This is in the spirit of the first step in the Corkum three-step model. The second-order perturbation correction terms are obtained when iℏω∂∂τ serves as a perturbation and τ is a dimensionless variable. The second-order adiabatic perturbation scheme is found to be an excellent approach for calculating the ac-field Floquet solutions in our test case studies of a simple one-dimensional time-periodic model Hamiltonian. It is straightforward to implement the perturbation approach presented here for calculating atomic and molecular energy shifts (positions) due to the interaction with low-frequency ac-fields using high-level electronic structure methods. This is enabled since standard quantum chemistry packages allow the calculations of atomic and molecular energy shifts due to the interaction with dc-fields. In addition to the shift of the energy positions, the energy widths (inverse lifetimes) can be obtained at the same level of theory. These energy shifts are functions of the laser parameters (low frequency, intensity, and polarization).

  9. Optical spectroscopy of rubidium Rydberg atoms with a 297 nm frequency doubled dye laser

    International Nuclear Information System (INIS)

    Becker, Th.; Germann, Th.; Thoumany, P.; Stania, G.; Urbonas, L.; Haensch, T.

    2008-01-01

    Full text: Rydberg atoms have played an important role in atomic physics and optical spectroscopy since many years. Due to their long lifetime and the big dipole matrix element between neighbouring Rydberg levels they are an essential tool in microwave cavity-qed experiments. Ultracold Rydberg gases are a promising candidate for realizing controlled quantum gates in atomic ensembles. In most experiments Rydberg atoms are detected destructively, where the optically excited atoms are first ionized followed by an electronic detection of the ionization products. A Doppler-free purely optical detection was reported in a room temperature cell and in an atomic beam apparatus using the technique of electromagnetically induced transparency. In all these experiments the Rydberg atoms are excited with two lasers in a two-step ladder configuration. Here we show that Doppler-free purely optical spectroscopy is also possible with a one step excitation scheme involving a UV laser at 297 nm. We excite the 85 Rb isotope from the 5S 1/2 ground state to the 63P 3/2 state with a frequency doubled dye laser in a room temperature gas cell without buffer gas. Rydberg transitions are detected by monitoring the absorption of 780 nm laser light which is superimposed on the UV light and resonant with one hyperfine component of the Rubidium D2 line. With these two lasers we realize a V-scheme and utilize the quantum amplification effect due to the different natural lifetimes of the upper levels of the two transitions: an excitation into the 63P level hinders many absorption-emission cycles of the D2 transition and leads to a reduced absorption on that line. We discuss the shape of the observed spectra in the context of electron shelving and EIT experiments. By applying a frequency modulation to the UV laser, we can obtain dispersive signals which can be used to stabilize the laser to a specific Rydberg transition. By shifting the frequency of the 780 nm laser to crossover resonances in the

  10. LABORATORY FREQUENCY REDISTRIBUTION FUNCTION FOR THE POLARIZED Λ-TYPE THREE-TERM ATOM

    Energy Technology Data Exchange (ETDEWEB)

    Casini, R. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Manso Sainz, R. [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

    2016-12-20

    We present the frequency redistribution function for a polarized three-term atom of the Λ-type in the collisionless regime, and we specialize it to the case where both the initial and final terms of the three-state transition are metastable (i.e., with infinitely sharp levels). This redistribution function represents a generalization of the well-known R {sub II} function to the case where the lower terms of the transition can be polarized and carry atomic coherence, and it can be applied to the investigation of polarized line formation in tenuous plasmas, where collisional rates may be low enough that anisotropy-induced atomic polarization survives even in the case of metastable levels.

  11. Microwave-to-optical frequency conversion with a Rydberg atom coupled to a coplanar waveguide

    Science.gov (United States)

    Gard, Bryan; Jacobs, Kurt; McDermott, Robert; Saffman, Mark

    2017-04-01

    A primary candidate for converting quantum information from microwave to optical frequencies is the use of Rydberg states of a single atom trapped near a surface. The fact that the Rydberg states possess both large electric dipole moments and microwave transition frequencies allows them to interact with superconducting mesoscopic circuits. By considering a concrete example, that of a Cesium atom, and using numerical search methods to optimize the control protocols, we determine the fidelities and transmission rates that could be achievable with such a device. We show that while protocols that exploit the adiabatic STIRAP mechanism provide the best raw transfer fidelities, the fastest communication speeds can be obtained by using heralding, which allows one to remove the adiabatic constraint. Support from Oak Ridge Associated Universities.

  12. Coherent storage of temporally multimode light using a spin-wave atomic frequency comb memory

    International Nuclear Information System (INIS)

    Gündoğan, M; Mazzera, M; Ledingham, P M; Cristiani, M; De Riedmatten, H

    2013-01-01

    We report on the coherent and multi-temporal mode storage of light using the full atomic frequency comb memory scheme. The scheme involves the transfer of optical atomic excitations in Pr 3+ :Y 2 SiO 5 to spin waves in hyperfine levels using strong single-frequency transfer pulses. Using this scheme, a total of five temporal modes are stored and recalled on-demand from the memory. The coherence of the storage and retrieval is characterized using a time-bin interference measurement resulting in visibilities higher than 80%, independent of the storage time. This coherent and multimode spin-wave memory is promising as a quantum memory for light. (paper)

  13. On the Power Dependence of Extraneous Microwave Fields in Atomic Frequency Standards

    Science.gov (United States)

    2005-01-01

    uncertainty”, Metrologia 35 (1998) pp. 829-845. [6] K. Dorenwendt and A. Bauch, “Spurious Microwave Fields in Caesium Atomic Beam Standards...Cesium Beam Clocks Induced by Microwave Leakages”, IEEE Trans. UFFC 45 (1998)728-738. [8] M. Abgrall, “Evaluation des Performances de la Fontaine...Proc of the EFTF 2005 – in press. [12] A. DeMarchi, “The Optically Pumped Caesium Fountain: 10-15 Frequency Accuracy?”, Metrologia 18 (1982) pp

  14. Quantum state population transfer of lithium atoms induced by frequency-chirped laser pulses

    International Nuclear Information System (INIS)

    Ma Huanqiang; Zhang Xianzhou; Jia Guangrui; Zhang Yonghui; Jiang Lijuan

    2011-01-01

    Using the time-dependent multilevel approach (TDMA) and B-splines function, we have calculated the five quantum state population transfer of rydberg lithium atoms. We also analyse the influence of the four major parameters of the frequency-chirped laser pulses field on transition. The result shows that the population can be completely transferred to the target state by changing the parameters of the laser pulse and achieve manual controls to a certain degree. (authors)

  15. Microwave-to-optical frequency conversion using a cesium atom coupled to a superconducting resonator

    Science.gov (United States)

    Gard, Bryan T.; Jacobs, Kurt; McDermott, R.; Saffman, M.

    2017-07-01

    A candidate for converting quantum information from microwave to optical frequencies is the use of a single atom that interacts with a superconducting microwave resonator on one hand and an optical cavity on the other. The large electric dipole moments and microwave transition frequencies possessed by Rydberg states allow them to couple strongly to superconducting devices. Lasers can then be used to connect a Rydberg transition to an optical transition to realize the conversion. Since the fundamental source of noise in this process is spontaneous emission from the atomic levels, the resulting control problem involves choosing the pulse shapes of the driving lasers so as to maximize the transfer rate while minimizing this loss. Here we consider the concrete example of a cesium atom, along with two specific choices for the levels to be used in the conversion cycle. Under the assumption that spontaneous emission is the only significant source of errors, we use numerical optimization to determine the likely rates for reliable quantum communication that could be achieved with this device. These rates are on the order of a few megaqubits per second.

  16. Quantitative measurement of solvation shells using frequency modulated atomic force microscopy

    Science.gov (United States)

    Uchihashi, T.; Higgins, M.; Nakayama, Y.; Sader, J. E.; Jarvis, S. P.

    2005-03-01

    The nanoscale specificity of interaction measurements and additional imaging capability of the atomic force microscope make it an ideal technique for measuring solvation shells in a variety of liquids next to a range of materials. Unfortunately, the widespread use of atomic force microscopy for the measurement of solvation shells has been limited by uncertainties over the dimensions, composition and durability of the tip during the measurements, and problems associated with quantitative force calibration of the most sensitive dynamic measurement techniques. We address both these issues by the combined use of carbon nanotube high aspect ratio probes and quantifying the highly sensitive frequency modulation (FM) detection technique using a recently developed analytical method. Due to the excellent reproducibility of the measurement technique, additional information regarding solvation shell size as a function of proximity to the surface has been obtained for two very different liquids. Further, it has been possible to identify differences between chemical and geometrical effects in the chosen systems.

  17. Measurement of the 1S-2S frequency in atomic hydrogen

    International Nuclear Information System (INIS)

    Hildum, E.A.

    1986-01-01

    A first precise measurement of the 1S-2S energy interval in atomic hydrogen was obtained by observing the 1S-2S transition in an atomic beam by pulsed Doppler-free two-photon spectroscopy and using an interferometrically calibrated line of 130 Te 2 at 486 nm as the references. The measured 1S-2S frequency is 2,466,061 395.6(4.9)MHz. With the calculated 1S Lamb shift, the 1S-2S frequency yields a value for the Rydberg constant, R/sub ∞/ = 109,737.314 92(22) cm -1 , which is not in good agreement with the most recent previously measured value, 109,737.315 44(11) cm -1 , obtained by S.R. Amin et al. It is, however, in good agreement with a previous Rydberg value, 109,737.315 04(32) cm -1 , measured by J.E.M. Goldsmith. If the Rydberg constant is taken as given, the 1S-2S frequency determines a value for the 1S Lamb shift. With Amin's Rydberg, the measured Lamb shift is 8161.0(5.4) MHz, in poor agreement with the theoretical value of 8149.43(8) MHz. With Goldsmith's Rydberg, the measurement Lamb shift is 8151.0(8.7) MHz, in good agreement with theory

  18. Coherent spectroscopy of a {Lambda} atomic system and its prospective application to tunable frequency offset locking

    Energy Technology Data Exchange (ETDEWEB)

    Kale, Y B [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Ray, Ayan [Radioactive Ion Beam Group, Variable Energy Cyclotron Centre, Kolkata 700064 (India); Lawande, Q V [Theoretical Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Jagatap, B N, E-mail: yogeshwar84@rediffmail.com, E-mail: ayan_ray_in@rediffmail.com, E-mail: bnj@barc.gov.in [Atomic and Molecular Physics Division and Homi Bhabha National Institute, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2011-09-15

    We investigate the coherent pump-probe spectroscopy of a three-level {Lambda} system, 6s{sub 1/2}F = 3,4{yields}6p{sub 3/2}F{sup '}= 4, in the hyperfine manifold of D{sub 2} transition (852 nm) of cesium with particular reference to the sub-Doppler linewidth resonance arising from Aulter-Townes (AT) splitting and the possibility of using it for realizing a scheme for tunable atomic frequency offset locking (AFOL). We discuss here the theoretical framework for a {Lambda} system interacting with a coherent pump and probe and use it to describe the process of modulation transfer in the AT and electromagnetically induced transparency regimes. We further employ an experimental scheme consisting of a strong pump and a pair of weak probes to resolve the sub-Doppler linewidth ({approx}8 MHz) AT resonance and study its dependence on pump intensity and detuning. In order to explore the possibility of using such a sub-Doppler linewidth resonance for AFOL, we use its first derivative signal as a frequency discriminator to stabilize the probe laser. The frequency stability of the probe is characterized by means of error signal analysis. This study reveals that while the frequency stability of the AT locked laser is limited by the pump laser, the tuning range of the offset frequency lock can cover the entire Doppler profile and its immediate neighbourhood, thereby providing a simple and cost effective alternative to the external modulator. The study described in this paper contributes to the discussion on the subtle link between dressed state spectroscopy and AFOL, which is relevant for developing a master-slave-type laser system in the domain of coherent photon-atom interaction.

  19. Atoms as nonlinear mixers for detection of quantum correlations at ultrahigh frequencies

    International Nuclear Information System (INIS)

    Georgiades, N.P.; Polzik, E.S.; Kimble, H.J.

    1997-01-01

    Measurements of quantum correlations are reported for a frequency difference of 25 THz between the signal and idler output fields generated by a subthreshold nondegenerate optical parametric oscillator. By simultaneously exciting a two-photon transition in atomic Cs by a combination of signal, idler, and open-quotes references oscillatorclose quotes fields, we record modulation of the excited-state population due to quantum interference between two alternative excitation pathways. The observed phase-sensitive modulation is proportional to the correlation function left-angle E s E i right-angle for the quantized signal and idler fields. copyright 1997 The American Physical Society

  20. Atoms

    International Nuclear Information System (INIS)

    Fuchs, Alain; Villani, Cedric; Guthleben, Denis; Leduc, Michele; Brenner, Anastasios; Pouthas, Joel; Perrin, Jean

    2014-01-01

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

  1. Localization of cesium on montmorillonite surface investigated by frequency modulation atomic force microscopy

    Science.gov (United States)

    Araki, Yuki; Satoh, Hisao; Okumura, Masahiko; Onishi, Hiroshi

    2017-11-01

    Cation exchange of clay mineral is typically analyzed without microscopic study of the clay surfaces. In order to reveal the distribution of exchangeable cations at the clay surface, we performed in situ atomic-scale observations of the surface changes in Na-rich montmorillonite due to exchange with Cs cations using frequency modulation atomic force microscopy (FM-AFM). Lines of protrusion were observed on the surface in aqueous CsCl solution. The amount of Cs of the montmorillonite particles analyzed by energy dispersive X-ray spectrometry was consistent with the ratio of the number of linear protrusions to all protrusions in the FM-AFM images. The results showed that the protrusions represent adsorbed Cs cations. The images indicated that Cs cations at the surface were immobile, and their occupancy remained constant at 10% of the cation sites at the surface with different immersion times in the CsCl solution. This suggests that the mobility and the number of Cs cations at the surface are controlled by the permanent charge of montmorillonite; however, the Cs distribution at the surface is independent of the charge distribution of the inner silicate layer. Our atomic-scale observations demonstrate that surface cations are distributed in different ways in montmorillonite and mica.

  2. Frequency modulation atomic force microscopy in ambient environments utilizing robust feedback tuning

    Science.gov (United States)

    Kilpatrick, J. I.; Gannepalli, A.; Cleveland, J. P.; Jarvis, S. P.

    2009-02-01

    Frequency modulation atomic force microscopy (FM-AFM) is rapidly evolving as the technique of choice in the pursuit of high resolution imaging of biological samples in ambient environments. The enhanced stability afforded by this dynamic AFM mode combined with quantitative analysis enables the study of complex biological systems, at the nanoscale, in their native physiological environment. The operational bandwidth and accuracy of constant amplitude FM-AFM in low Q environments is heavily dependent on the cantilever dynamics and the performance of the demodulation and feedback loops employed to oscillate the cantilever at its resonant frequency with a constant amplitude. Often researchers use ad hoc feedback gains or instrument default values that can result in an inability to quantify experimental data. Poor choice of gains or exceeding the operational bandwidth can result in imaging artifacts and damage to the tip and/or sample. To alleviate this situation we present here a methodology to determine feedback gains for the amplitude and frequency loops that are specific to the cantilever and its environment, which can serve as a reasonable "first guess," thus making quantitative FM-AFM in low Q environments more accessible to the nonexpert. This technique is successfully demonstrated for the low Q systems of air (Q ˜40) and water (Q ˜1). In addition, we present FM-AFM images of MC3T3-E1 preosteoblast cells acquired using the gains calculated by this methodology demonstrating the effectiveness of this technique.

  3. Frequency shift, damping, and tunneling current coupling with quartz tuning forks in noncontact atomic force microscopy

    Science.gov (United States)

    Nony, Laurent; Bocquet, Franck; Para, Franck; Loppacher, Christian

    2016-09-01

    A combined experimental and theoretical approach to the coupling between frequency-shift (Δ f ) , damping, and tunneling current (It) in combined noncontact atomic force microscopy/scanning tunneling microscopy using quartz tuning forks (QTF)-based probes is reported. When brought into oscillating tunneling conditions, the tip located at the QTF prong's end radiates an electromagnetic field which couples to the QTF prong motion via its piezoelectric tensor and loads its electrodes by induction. Our approach explains how those It-related effects ultimately modify the Δ f and the damping measurements. This paradigm to the origin of the coupling between It and the nc-AFM regular signals relies on both the intrinsic piezoelectric nature of the quartz constituting the QTF and its electrodes design.

  4. High frequency measurements of shot noise suppression in atomic-scale metal contacts

    Science.gov (United States)

    Wheeler, Patrick J.; Evans, Kenneth; Russom, Jeffrey; King, Nicholas; Natelson, Douglas

    2009-03-01

    Shot noise provides a means of assessing the number and transmission coefficients of transmitting channels in atomic- and molecular-scale junctions. Previous experiments at low temperatures in metal and semiconductor point contacts have demonstrated the expected suppression of shot noise when junction conductance is near an integer multiple of the conductance quantum, G0≡2e^2/h. Using high frequency techniques, we demonstrate the high speed acquisition of such data at room temperature in mechanical break junctions. In clean Au contacts conductance histograms with clear peaks at G0, 2G0, and 3G0 are acquired within hours, and histograms of simultaneous measurements of the shot noise show clear suppression at those conductance values. We describe the dependence of the noise on bias voltage and analyze the noise vs. conductance histograms in terms of a model that averages over transmission coefficients.

  5. Sub-nanometer-resolution imaging of peptide nanotubes in water using frequency modulation atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sugihara, Tomoki; Hayashi, Itsuho; Onishi, Hiroshi [Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan); Kimura, Kenjiro, E-mail: kimura@gold.kobe-u.ac.jp [Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan); Tamura, Atsuo [Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan)

    2013-06-20

    Highlights: ► Peptide nanotubes were aligned on highly oriented pyrolytic graphite surface. ► We visualized sub-nanometer-scale structure on peptide nanotube surface in water. ► We observed hydration structure at a peptide nanotube/water interface. - Abstract: Peptide nanotubes are self-assembled fibrous materials composed of cyclic polypeptides. Recently, various aspects of peptide nanotubes have been studied, in particular the utility of different methods for making peptide nanotubes with diverse designed functions. In order to investigate the relationship between formation, function and stability, it is essential to analyze the precise structure of peptide nanotubes. Atomic-scale surface imaging in liquids was recently achieved using frequency modulation atomic force microscopy with improved force sensing. Here we provide a precise surface structural analysis of peptide nanotubes in water without crystallizing them obtained by imaging the nanotubes at the sub-nanometer scale in water. In addition, the local hydration structure around the peptide nanotubes was observed at the nanotube/water interface.

  6. Multiplicity dependence of matrix-induced frequency shifts for atomic transitions of the group 12 metals in rare gas solids

    International Nuclear Information System (INIS)

    Laursen, S.L.; Cartland, H.E.

    1991-01-01

    Atomic resonances of the group 12 metal atoms, Hg, Cd, and Zn, undergo frequency shifts from the gas phase atomic line when trapped in rare gas matrices of Ar, Kr, and Xe at 12 K. As expected, the shifts are approximately linear in polarizability of the rare gas, but the slope of this line depends on whether the transition in question is 1 P 1 left-arrow 1 S 0 or 3 P 1 left-arrow 1 S 0 . Thus the matrix-induced frequency shift is dependent on the singlet or triplet nature of the excited state as well as on the matrix material. This dependence on multiplicity is discussed in terms of interactions between the excited-state atomic orbitals and the matrix. The results are compared to matrix studies of other metals and to related gas-phase work on diatomic van der Waals complexes of group 12 metals with rare gases

  7. Atom

    International Nuclear Information System (INIS)

    Auffray, J.P.

    1997-01-01

    The atom through centuries, has been imagined, described, explored, then accelerated, combined...But what happens truly inside the atom? And what are mechanisms who allow its stability? Physicist and historian of sciences, Jean-Paul Auffray explains that these questions are to the heart of the modern physics and it brings them a new lighting. (N.C.)

  8. Manipulating Si(100) at 5 K using qPlus frequency modulated atomic force microscopy: Role of defects and dynamics in the mechanical switching of atoms

    Science.gov (United States)

    Sweetman, A.; Jarvis, S.; Danza, R.; Bamidele, J.; Kantorovich, L.; Moriarty, P.

    2011-08-01

    We use small-amplitude qPlus frequency modulated atomic force microscopy (FM-AFM), at 5 K, to investigate the atomic-scale mechanical stability of the Si(100) surface. By operating at zero applied bias the effect of tunneling electrons is eliminated, demonstrating that surface manipulation can be performed by solely mechanical means. Striking differences in surface response are observed between different regions of the surface, most likely due to variations in strain associated with the presence of surface defects. We investigate the variation in local energy surface by ab initio simulation, and comment on the dynamics observed during force spectroscopy.

  9. Length-extension resonator as a force sensor for high-resolution frequency-modulation atomic force microscopy in air.

    Science.gov (United States)

    Beyer, Hannes; Wagner, Tino; Stemmer, Andreas

    2016-01-01

    Frequency-modulation atomic force microscopy has turned into a well-established method to obtain atomic resolution on flat surfaces, but is often limited to ultra-high vacuum conditions and cryogenic temperatures. Measurements under ambient conditions are influenced by variations of the dew point and thin water layers present on practically every surface, complicating stable imaging with high resolution. We demonstrate high-resolution imaging in air using a length-extension resonator operating at small amplitudes. An additional slow feedback compensates for changes in the free resonance frequency, allowing stable imaging over a long period of time with changing environmental conditions.

  10. A hybrid polarization-selective atomic sensor for radio-frequency field detection with a passive resonant-cavity field amplifier

    OpenAIRE

    Anderson, David A.; Paradis, Eric G.; Raithel, Georg

    2018-01-01

    We present a hybrid atomic sensor that realizes radio-frequency electric field detection with intrinsic field amplification and polarization selectivity for robust high-sensitivity field measurement. The hybrid sensor incorporates a passive resonator element integrated with an atomic vapor cell that provides amplification and polarization selectivity for detection of incident radio-frequency fields. The amplified intra-cavity radio-frequency field is measured by atoms using a quantum-optical ...

  11. Compact field programmable gate array-based pulse-sequencer and radio-frequency generator for experiments with trapped atoms

    Energy Technology Data Exchange (ETDEWEB)

    Pruttivarasin, Thaned, E-mail: thaned.pruttivarasin@riken.jp [Quantum Metrology Laboratory, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Katori, Hidetoshi [Quantum Metrology Laboratory, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Innovative Space-Time Project, ERATO, JST, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2015-11-15

    We present a compact field-programmable gate array (FPGA) based pulse sequencer and radio-frequency (RF) generator suitable for experiments with cold trapped ions and atoms. The unit is capable of outputting a pulse sequence with at least 32 transistor-transistor logic (TTL) channels with a timing resolution of 40 ns and contains a built-in 100 MHz frequency counter for counting electrical pulses from a photo-multiplier tube. There are 16 independent direct-digital-synthesizers RF sources with fast (rise-time of ∼60 ns) amplitude switching and sub-mHz frequency tuning from 0 to 800 MHz.

  12. A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock

    Energy Technology Data Exchange (ETDEWEB)

    François, B.; Boudot, R. [FEMTO-ST, CNRS, Université de Franche-Comté, 26 chemin de l' Epitaphe, 25030 Besançon (France); Calosso, C. E. [INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Danet, J. M. [LNE-SYRTE, Observatoire de Paris, CNRS-UPMC, 61 avenue de l' Observatoire, 75014 Paris (France)

    2014-09-15

    We report the development, absolute phase noise, and residual phase noise characterization of a 9.192 GHz microwave frequency synthesis chain devoted to be used as a local oscillator in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). It is based on frequency multiplication of an ultra-low phase noise 100 MHz oven-controlled quartz crystal oscillator using a nonlinear transmission line-based chain. Absolute phase noise performances of the 9.192 GHz output signal are measured to be −42, −100, −117 dB rad{sup 2}/Hz and −129 dB rad{sup 2}/Hz at 1 Hz, 100 Hz, 1 kHz, and 10 kHz offset frequencies, respectively. Compared to current results obtained in a state-of-the-art CPT-based frequency standard developed at LNE-SYRTE, this represents an improvement of 8 dB and 10 dB at f = 166 Hz and f = 10 kHz, respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported at a level of 6.2 × 10{sup −14} at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out.

  13. Measuring the spin polarization of alkali-metal atoms using nuclear magnetic resonance frequency shifts of noble gases

    Directory of Open Access Journals (Sweden)

    X. H. Liu

    2015-10-01

    Full Text Available We report a novel method of measuring the spin polarization of alkali-metal atoms by detecting the NMR frequency shifts of noble gases. We calculated the profile of 87Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the 87Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the 87Rb atoms and calculated its polarization degrees at different temperatures. The behavior of frequency shifts versus temperature in experiment was consistent with theoretical calculation, which may be used as compensative signal for the NMRG closed-loop control system.

  14. Effects of an applied low frequency field on the dynamics of a two-level atom interacting with a single-mode field

    International Nuclear Information System (INIS)

    Xun-Wei, Xu; Nian-Hua, Liu

    2010-01-01

    The effects of an applied low frequency field on the dynamics of a two-level atom interacting with a single-mode field are investigated. It is shown that the time evolution of the atomic population is mainly controlled by the coupling constants and the frequency of the low frequency field, which leads to a low frequency modulation function for the time evolution of the upper state population. The amplitude of the modulation function becomes larger as the coupling constants increase. The frequency of the modulation function is proportional to the frequency of the low frequency field, and decreases with increasing coupling constant. (classical areas of phenomenology)

  15. Competition between Final-State and Pairing-Gap Effects in the Radio-Frequency Spectra of Ultracold Fermi Atoms

    International Nuclear Information System (INIS)

    Perali, A.; Pieri, P.; Strinati, G. C.

    2008-01-01

    The radio-frequency spectra of ultracold Fermi atoms are calculated by including final-state interactions affecting the excited level of the transition and compared with the experimental data. A competition is revealed between pairing-gap effects which tend to push the oscillator strength toward high frequencies away from threshold and final-state effects which tend instead to pull the oscillator strength toward threshold. As a result of this competition, the position of the peak of the spectra cannot be simply related to the value of the pairing gap, whose extraction thus requires support from theoretical calculations

  16. A new time-frequency method to reveal quantum dynamics of atomic hydrogen in intense laser pulses: Synchrosqueezing transform

    International Nuclear Information System (INIS)

    Sheu, Yae-lin; Hsu, Liang-Yan; Wu, Hau-tieng; Li, Peng-Cheng; Chu, Shih-I

    2014-01-01

    This study introduces a new adaptive time-frequency (TF) analysis technique, the synchrosqueezing transform (SST), to explore the dynamics of a laser-driven hydrogen atom at an ab initio level, upon which we have demonstrated its versatility as a new viable venue for further exploring quantum dynamics. For a signal composed of oscillatory components which can be characterized by instantaneous frequency, the SST enables rendering the decomposed signal based on the phase information inherited in the linear TF representation with mathematical support. Compared with the classical type of TF methods, the SST clearly depicts several intrinsic quantum dynamical processes such as selection rules, AC Stark effects, and high harmonic generation

  17. Searching for an oscillating massive scalar field as a dark matter candidate using atomic hyperfine frequency comparisons

    OpenAIRE

    Hees, A.; Guéna, J.; Abgrall, M.; Bize, S.; Wolf, P.

    2016-01-01

    We use six years of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but pr...

  18. Frequency shift due to blackbody radiation in a cesium atomic fountain and improvement of the clock performances

    International Nuclear Information System (INIS)

    Zhang, S.

    2004-07-01

    FO1 was the first caesium fountain primary frequency standard in the world. The most recent evaluation in 2002 before improvement reached an accuracy of 1*10 -15 when operated with optical molasses. Working as an extremely precise and stable instrument, FO1 has contributed to fundamental physics and technical measurements: - Frequency comparison between Cs and Rb fountains over an interval of 5 years sets an upper limit for a possible variation of the fine structure constant as |alpha/alpha| -15 /y. The resolution is about 5 times better than the previous test in our laboratory. The projected accuracy of the space clock PHARAO is 1*10 -16 . We confirmed its Ramsey cavity performance by testing the phase difference between the two interaction zones in FO1. The measured temperature T dependent frequency shift of the Cs clock induced by the blackbody radiation field is given as nu(T)=154(6)*10 -6 *(T/300) 4 [1+ε(T/300) 2 ] Hz with the theoretical value ε = 0,014. The obtained accuracy represents a 3 times improvement over the previous measurement by the PTB group. Some improvements have been carried out on FO1. The new FO1 version works directly with optical molasses loaded by a laser slowed atomic beam. The application of the adiabatic passage method to perform the state selection allows us to determine the atom number dependent frequency shifts due to the cold collision and cavity pulling effects at a level of of 10 -16 . Recently, the obtained frequency stability is 2,8*10 -14 *τ -1/2 for about 4*10 6 detected atoms. The accuracy is currently under evaluation, the expected value is a few times 10 -16 . (author)

  19. Polarization switching detection method using a ferroelectric liquid crystal for dichroic atomic vapor laser lock frequency stabilization techniques.

    Science.gov (United States)

    Dudzik, Grzegorz; Rzepka, Janusz; Abramski, Krzysztof M

    2015-04-01

    We present a concept of the polarization switching detection method implemented for frequency-stabilized lasers, called the polarization switching dichroic atomic vapor laser lock (PSDAVLL) technique. It is a combination of the well-known dichroic atomic vapor laser lock method for laser frequency stabilization with a synchronous detection system based on the surface-stabilized ferroelectric liquid crystal (SSFLC).The SSFLC is a polarization switch and quarter wave-plate component. This technique provides a 9.6 dB better dynamic range ratio (DNR) than the well-known two-photodiode detection configuration known as the balanced polarimeter. This paper describes the proposed method used practically in the VCSEL laser frequency stabilization system. The applied PSDAVLL method has allowed us to obtain a frequency stability of 2.7×10⁻⁹ and a reproducibility of 1.2×10⁻⁸, with a DNR of detected signals of around 81 dB. It has been shown that PSDAVLL might be successfully used as a method for spectra-stable laser sources.

  20. Coherent Frequency Shifter, Optical Isolator, Lasers on an Integrated Platform for Cold Atom Microsystems

    Science.gov (United States)

    2017-10-11

    frequency shifting with < 10 % leakage ; (5) experimental demonstration achieving frequency shifting with < 3 dB forward optical loss; (6) 29.3 dBm RF...using heterodyne detection . (b) 100 MHz up-conversion, 20 dB side lobe suppression. (c) 100 MHz down-conversion, 14 dB side lobe suppression...shifting with < 10 % leakage ; (5) experimental demonstration achieving frequency shifting with < 3 dB forward optical loss; (6) 29.3 dBm RF power

  1. High-frequency electrode less lamps for application in atomic absorption analysis

    International Nuclear Information System (INIS)

    Gavare, Z.; Revalde, G.; Skudra, A.; Ganeev, A.; Sholupov, S.

    2004-01-01

    Authors measured and optimised main characteristic of different EDL-s, interesting for their use in atomic absorption spectroscopy: working time, main spectral line intensities and spectral widths, as well as limits of detection for respective elements. In the experiment spectrometer MGA-915 was used. In the table the ultimate limits of detection (LOD) are compered for HF ED lamps and HJC lamps. LOD for HF EDL lamps are 1.5 - 8 times lower than ones for HCL-s

  2. Atomic resolution ultrafast scanning tunneling microscope with scan rate breaking the resonant frequency of a quartz tuning fork resonator.

    Science.gov (United States)

    Li, Quanfeng; Lu, Qingyou

    2011-05-01

    We present an ultra-fast scanning tunneling microscope with atomic resolution at 26 kHz scan rate which surpasses the resonant frequency of the quartz tuning fork resonator used as the fast scan actuator. The main improvements employed in achieving this new record are (1) fully low voltage design (2) independent scan control and data acquisition, where the tuning fork (carrying a tip) is blindly driven to scan by a function generator with the scan voltage and tunneling current (I(T)) being measured as image data (this is unlike the traditional point-by-point move and measure method where data acquisition and scan control are switched many times).

  3. Searching for an Oscillating Massive Scalar Field as a Dark Matter Candidate Using Atomic Hyperfine Frequency Comparisons.

    Science.gov (United States)

    Hees, A; Guéna, J; Abgrall, M; Bize, S; Wolf, P

    2016-08-05

    We use 6 yrs of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions, and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but provide improved constraints on the coupling of the putative scalar field to standard matter. Our limits are complementary to previous results that were only sensitive to the fine structure constant and improve them by more than an order of magnitude when only a coupling to electromagnetism is assumed.

  4. Historical Review of Atomic Frequency Standards Used in Space Systems - 10 Year Update

    Science.gov (United States)

    2007-01-01

    section on 2006 predictions. The authors would like to thank Peter Cash, Bernardo Jaduszliwer, Bob Kern, Robert Lutwak , John Prestage, Bill Riley, and...258- 262. [17] R. Lutwak , D. Emmons, R. M. Garvey, and P. Vlitas, 2003, “Optically pumped cesium-beam frequency standard for GPS-III,” in

  5. Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip scanning probe microscopy applications

    International Nuclear Information System (INIS)

    Morawski, Ireneusz; Spiegelberg, Richard; Korte, Stefan; Voigtländer, Bert

    2015-01-01

    A method which allows scanning tunneling microscopy (STM) tip biasing independent of the sample bias during frequency modulated atomic force microscopy (AFM) operation is presented. The AFM sensor is supplied by an electronic circuit combining both a frequency shift signal and a tunneling current signal by means of an inductive coupling. This solution enables a control of the tip potential independent of the sample potential. Individual tip biasing is specifically important in order to implement multi-tip STM/AFM applications. An extensional quartz sensor (needle sensor) with a conductive tip is applied to record simultaneously topography and conductivity of the sample. The high resonance frequency of the needle sensor (1 MHz) allows scanning of a large area of the surface being investigated in a reasonably short time. A recipe for the amplitude calibration which is based only on the frequency shift signal and does not require the tip being in contact is presented. Additionally, we show spectral measurements of the mechanical vibration noise of the scanning system used in the investigations

  6. Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip scanning probe microscopy applications

    Energy Technology Data Exchange (ETDEWEB)

    Morawski, Ireneusz [Peter Grünberg Institut (PGI-3) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich (Germany); Institute of Experimental Physics, University of Wrocław, pl. M. Borna 9, 50-204 Wrocław (Poland); Spiegelberg, Richard; Korte, Stefan; Voigtländer, Bert [Peter Grünberg Institut (PGI-3) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich (Germany)

    2015-12-15

    A method which allows scanning tunneling microscopy (STM) tip biasing independent of the sample bias during frequency modulated atomic force microscopy (AFM) operation is presented. The AFM sensor is supplied by an electronic circuit combining both a frequency shift signal and a tunneling current signal by means of an inductive coupling. This solution enables a control of the tip potential independent of the sample potential. Individual tip biasing is specifically important in order to implement multi-tip STM/AFM applications. An extensional quartz sensor (needle sensor) with a conductive tip is applied to record simultaneously topography and conductivity of the sample. The high resonance frequency of the needle sensor (1 MHz) allows scanning of a large area of the surface being investigated in a reasonably short time. A recipe for the amplitude calibration which is based only on the frequency shift signal and does not require the tip being in contact is presented. Additionally, we show spectral measurements of the mechanical vibration noise of the scanning system used in the investigations.

  7. Characterization of atomic oxygen in a Hollow Cathode Radio-Frequency Plasma and study its efficiency

    International Nuclear Information System (INIS)

    Naddaf, M.; Saloum, S.

    2011-01-01

    The atomic oxygen (AO) generated in the remote oxygen plasma of the HCD-L300 source, has been fully diagnosed by various conventional techniques. The density of AO was found to vary from (1-10)x10 1 9 m - 3 depending on the operating conditions and parameters. The interaction of the oxygen plasma with silver and gold thin films is investigated by gravimetric analysis, scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) spectroscopy. The effect of AO on surface wetting and energy of polymeric materials is also investigated by using contact angle measurements and analysis technique. From applied point of view, production of super hydrophobic Teflon surface and the significant enhancement in the surface free energy of polyimide and polyamide are considered the most important obtained results in the present work. (author)

  8. Low-frequency-field-induced spontaneous-emission interference in a two-level atom placed in an anisotropic photonic crystal

    International Nuclear Information System (INIS)

    Li Gaoxiang; Evers, Joerg; Keitel, Christoph H

    2005-01-01

    We investigate the spontaneous-emission properties of a two-level atom embedded in a three-dimensional anisotropic photonic crystal. In addition to the modified density of states, the atom is driven by a coherent intense low-frequency field (LFF), which creates additional multiphoton decay channels with the exchange of two low-frequency photons and one spontaneous photon during an atomic transition. Due to the low frequency of the applied field, the various transition pathways may interfere with each other and thus give rise to a modified system dynamics. We find that even if all the atomic (bare and induced) transition frequencies are in the conducting band of the photonic crystal, there still may exist a photon-atom bound state in coexistence with propagating modes. The system also allows us to generate narrow lines in the spontaneous-emission spectrum. This spectrum is a function of the distance of the observer from the atom due to the band gap in the photonic crystal. The system properties depend on three characteristic frequencies, which are influenced by quantum interference effects. Thus these results can be attributed to a combination of interference and band-gap effects

  9. A diode-laser optical frequency standard based on laser-cooled Ca atoms: sub-kilohertz spectroscopy by optical shelving detection

    International Nuclear Information System (INIS)

    Oates, C.W.; Bondu, F.; Fox, R.W.; Hollberg, L.

    1999-01-01

    We report an optical frequency standard at 657 nm based on laser-cooled/trapped Ca atoms. The system consists of a novel, compact magneto-optic trap which uses 50 mW of frequency-doubled diode laser light at 423 nm and can trap >10 7 Ca atoms in 20 ms. High resolution spectroscopy on this atomic sample using the narrow 657 nm intercombination line resolves linewidths (FWHM) as narrow as 400 Hz, the natural linewidth of the transition. The spectroscopic signal-to-noise ratio is enhanced by an order of magnitude with the implementation of a ''shelving'' detection scheme on the 423 nm transition. Our present apparatus achieves a fractional frequency instability of 5 x 10 -14 in 1 s with a potential atom shot-noise-limited performance of 10 -16 τ -1/2 and excellent prospects for high accuracy. (orig.)

  10. Frequency chain to measure the 2S-8S/8D transitions in atomic hydrogen: measurement of the Rydberg constant in frequency unit; Chaine de frequence optique pour mesurer les transitions 2S-8S/8D dans l'atome d'hydrogene: mesure de la constante de Rydberg en unite de frequence

    Energy Technology Data Exchange (ETDEWEB)

    Nez, F

    1993-10-15

    The aim of this thesis is to make a pure measurement of the frequency of the 2S-8S/8D two-photon transition in atomic hydrogen. In that purpose we have built a frequency chain in which hydrogen frequencies are compared with the difference of two optical standards, the methane stabilized He-Ne laser (3.39 {mu}m) and the iodine stabilized He-Ne laser (633 nm). The radiation from a home made Ti-sapphire laser (TS2) at 778 nm is mixed, in a LiIO{sub 3} crystal, with the one of a auxiliary He-Ne laser at 3.39 {mu}m to produce a synthesized radiation at 633 nm. The frequency of the Ti-sapphire (TS1) laser used for the two photon excitation is 89 GHz away from the one of TS2. To compare these two lasers, we have used a Schottky diode. The two lasers and a microwave radiation at 89 GHz, produced by a Gunn diode, are focused on the Schottky diode. The Gunn diode is phase locked on an ultra-stable quartz oscillator. In this way, we have linked an optical frequency of atomic hydrogen to the cesium clock without interferometry. From our measurements, we have deduced a new value of the Rydberg constant: R{sub {infinity}} equals 109737.3156834 (24) cm{sup -1} with an uncertainty of 2.2 10{sup -11}. Our uncertainty is near the one of the Q.E.D calculations giving the theoretical values of the energy levels. This value, which is currently the most precise available, is in good agreement with the recent result obtained from the 1S-2S and 2S-4D transitions. (author)

  11. UTC(OP) based on LNE-SYRTE atomic fountain primary frequency standards

    International Nuclear Information System (INIS)

    Rovera, G.D.; Bize, S.; Chupin, B.; Guena, J.; Laurent, Ph; Rosenbusch, Ph.; Uhrich, P.; Abgrall, M.

    2016-01-01

    UTC(OP), the French national realization of the international coordinated universal time, was redesigned and rebuilt. The first step was the implementation in October 2012 of a new algorithm based on a H-maser and on atomic fountain data. Thanks to the new implementation, the stability of UTC(OP) was dramatically improved and UTC(OP) competes with the best time scales available today. Then the hardware generation and distribution of the UTC(OP) physical signals were replaced. Part of the new hardware is composed of commercial devices, but the key elements were specifically developed. One of them is a special switch that allows the UTC(OP) signals to be derived from one of two time scales, based on two different H-masers, which are generated simultaneously. This insures the continuity of the UTC(OP) signal even when a change of the reference H-maser is required. With the new hardware implementation, UTC(OP) is made available through three coherent signals: 100 MHz, 10 MHz and 1 PPS. For more than 3 years, UTC(OP) remained well below 10 ns close to UTC, with a difference even less than 5 ns if we except a short period around MJD 56650. (authors)

  12. High-resolution inelastic X-ray scattering to study the high-frequency atomic dynamics of disordered systems

    International Nuclear Information System (INIS)

    Monaco, G.

    2008-01-01

    The use of momentum-resolved inelastic X-ray scattering with meV energy resolution to study the high-frequency atomic dynamics in disordered systems is here reviewed. The typical realization of this experiment is described together with some common models used to interpret the measured spectra and to extract parameters of interest for the investigation of disordered systems. With the help of some selected examples, the present status of the field is discussed. Particular attention is given to those results which are still open for discussion or controversial, and which will require further development of the technique to be fully solved. Such an instrumental development seems nowadays possible at the light of recently proposed schemes for advanced inelastic X-ray scattering spectrometers. (author)

  13. Characterization of polymer surface structure and surface mechanical behaviour by sum frequency generation surface vibrational spectroscopy and atomic force microscopy

    International Nuclear Information System (INIS)

    Opdahl, Aric; Koffas, Telly S; Amitay-Sadovsky, Ella; Kim, Joonyeong; Somorjai, Gabor A

    2004-01-01

    Sum frequency generation (SFG) vibrational spectroscopy and atomic force microscopy (AFM) have been used to study polymer surface structure and surface mechanical behaviour, specifically to study the relationships between the surface properties of polymers and their bulk compositions and the environment to which the polymer is exposed. The combination of SFG surface vibrational spectroscopy and AFM has been used to study surface segregation behaviour of polyolefin blends at the polymer/air and polymer/solid interfaces. SFG surface vibrational spectroscopy and AFM experiments have also been performed to characterize the properties of polymer/liquid and polymer/polymer interfaces, focusing on hydrogel materials. A method was developed to study the surface properties of hydrogel contact lens materials at various hydration conditions. Finally, the effect of mechanical stretching on the surface composition and surface mechanical behaviour of phase-separated polyurethanes, used in biomedical implant devices, has been studied by both SFG surface vibrational spectroscopy and AFM. (topical review)

  14. Continuous-wave, single-frequency 229  nm laser source for laser cooling of cadmium atoms.

    Science.gov (United States)

    Kaneda, Yushi; Yarborough, J M; Merzlyak, Yevgeny; Yamaguchi, Atsushi; Hayashida, Keitaro; Ohmae, Noriaki; Katori, Hidetoshi

    2016-02-15

    Continuous-wave output at 229 nm for the application of laser cooling of Cd atoms was generated by the fourth harmonic using two successive second-harmonic generation stages. Employing a single-frequency optically pumped semiconductor laser as a fundamental source, 0.56 W of output at 229 nm was observed with a 10-mm long, Brewster-cut BBO crystal in an external cavity with 1.62 W of 458 nm input. Conversion efficiency from 458 nm to 229 nm was more than 34%. By applying a tapered amplifier (TA) as a fundamental source, we demonstrated magneto-optical trapping of all stable Cd isotopes including isotopes Cd111 and Cd113, which are applicable to optical lattice clocks.

  15. True atomic-scale imaging of a spinel Li{sub 4}Ti{sub 5}O{sub 12}(111) surface in aqueous solution by frequency-modulation atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kitta, Mitsunori, E-mail: m-kitta@aist.go.jp; Kohyama, Masanori [Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Onishi, Hiroshi [Department of Chemistry, Graduate School of Science, Kobe University 1-1 Rokkodai, Nada, Kobe 657-8501 (Japan)

    2014-09-15

    Spinel-type lithium titanium oxide (LTO; Li{sub 4}Ti{sub 5}O{sub 12}) is a negative electrode material for lithium-ion batteries. Revealing the atomic-scale surface structure of LTO in liquid is highly necessary to investigate its surface properties in practical environments. Here, we reveal an atomic-scale image of the LTO(111) surface in LiCl aqueous solution using frequency-modulation atomic force microscopy. Atomically flat terraces and single steps having heights of multiples of 0.5 nm were observed in the aqueous solution. Hexagonal bright spots separated by 0.6 nm were also observed on the flat terrace part, corresponding to the atomistic contrast observed in the ultrahigh vacuum condition, which suggests that the basic atomic structure of the LTO(111) surface is retained without dramatic reconstruction even in the aqueous solution.

  16. Frequency and Wavevector Dependence of the Atomic Level Stress-Stress Correlation Function in a Model Supercooled Liquid

    Science.gov (United States)

    Levashov, Valentin A.; Morris, James R.; Egami, Takeshi

    2012-02-01

    Temporal and spatial correlations among the local atomic level shear stresses were studied for a model liquid iron by molecular dynamics simulation [PRL 106,115703]. Integration over time and space of the shear stress correlation function F(r,t) yields viscosity via Green-Kubo relation. The stress correlation function in time and space F(r,t) was Fourier transformed to study the dependence on frequency, E, and wave vector, Q. The results, F(Q,E), showed damped shear stress waves propagating in the liquid for small Q at high and low temperatures. We also observed additional diffuse feature that appears as temperature is reduced below crossover temperature of potential energy landscape at relatively low frequencies at small Q. We suggest that this additional feature might be related to dynamic heterogeneity and boson peaks. We also discuss a relation between the time-scale of the stress-stress correlation function and the alpha-relaxation time of the intermediate self-scattering function S(Q,E).

  17. Efficient generation of a narrow-bandwidth and frequency-modulated beam pair from Yb atoms in a ladder configuration

    International Nuclear Information System (INIS)

    Song, Minsoo; Yoon, Tai Hyun

    2011-01-01

    We report on the generation of narrow-bandwidth and frequency-modulated cascaded emission of two photons from a collimated Yb atomic beam. Efficient population transfer from the ground state (6s 2 1 S 0 ) to upper state (6s7s 1 S 0 ), of which direct transition at 291.1 nm is dipole forbidden, is achieved through a resonant two-photon excitation enhanced by the electromagnetically induced transparency mediated by the intermediate state (6s6p 1 P 1 ). Then cascaded emission of two photons with a bandwidth of 54 MHz at 611.3 nm (idler) and 555.8 nm (signal) occurs in sequence from the upper state via the spin triplet state (6s 2 3 P 1 ). Numerical calculations of the density matrix equations taking into account the residual Doppler effect and strong driving fields successfully explain the experimental results for the idler and signal beam intensities depending on the various parameters of the driving fields. Synchronized optical switching and frequency-modulation characteristics of the idler and signal beams are also reported.

  18. Absolute atomic oxygen and nitrogen densities in radio-frequency driven atmospheric pressure cold plasmas: Synchrotron vacuum ultra-violet high-resolution Fourier-transform absorption measurements

    International Nuclear Information System (INIS)

    Niemi, K.; O'Connell, D.; Gans, T.; Oliveira, N. de; Joyeux, D.; Nahon, L.; Booth, J. P.

    2013-01-01

    Reactive atomic species play a key role in emerging cold atmospheric pressure plasma applications, in particular, in plasma medicine. Absolute densities of atomic oxygen and atomic nitrogen were measured in a radio-frequency driven non-equilibrium plasma operated at atmospheric pressure using vacuum ultra-violet (VUV) absorption spectroscopy. The experiment was conducted on the DESIRS synchrotron beamline using a unique VUV Fourier-transform spectrometer. Measurements were carried out in plasmas operated in helium with air-like N 2 /O 2 (4:1) admixtures. A maximum in the O-atom concentration of (9.1 ± 0.7)×10 20 m −3 was found at admixtures of 0.35 vol. %, while the N-atom concentration exhibits a maximum of (5.7 ± 0.4)×10 19 m −3 at 0.1 vol. %

  19. Procedure for 40K isotope separation from beam of potassium atoms using optical orientation of atoms and radio-frequency excitation of target isotope

    International Nuclear Information System (INIS)

    Nikitin, A.I.; Velichko, A.M.; Vnukov, A.V.; Mal'tsev, K.K.; Nabiev, Sh.Sh.

    1999-01-01

    The procedure for potassium isotope separation, which is liable to reduce of the prise of the product as compared with the up-to-date prise of the 40 K isotope obtained by means of electromagnetic procedure for isotope separation, is proposed. The scheme assumes the increasing flow of the wanted isotope at the sacrifice of the increasing intensity of atomic beam and the increase of the selectivity of need isotope atoms at the sacrifice of the the reduction in the square of collector profile. The objective is achieved that provide of polarized state of the potassium atoms is produced by optic orientation with circular-polarized light [ru

  20. The effect of drive frequency and set point amplitude on tapping forces in atomic force microscopy: simulation and experiment

    International Nuclear Information System (INIS)

    Legleiter, Justin

    2009-01-01

    In tapping mode atomic force microscopy (AFM), a sharp probe tip attached to an oscillating cantilever is allowed to intermittently strike a surface. By raster scanning the probe while monitoring the oscillation amplitude of the cantilever via a feedback loop, topographical maps of surfaces with nanoscale resolution can be acquired. While numerous studies have employed numerical simulations to elucidate the time-resolved tapping force between the probe tip and surface, until recent technique developments, specific read-outs from such models could not be experimentally verified. In this study, we explore, via numerical simulation, the impact of imaging parameters, i.e. set point ratio and drive frequency as a function of resonance, on time-varying tip-sample force interactions, which are directly compared to reconstructed tapping forces from real AFM experiments. As the AFM model contains a feedback loop allowing for the simulation of the entire scanning process, we further explore the impact that various tip-sample force have on the entire imaging process.

  1. Revealing molecular-level surface structure of amyloid fibrils in liquid by means of frequency modulation atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fukuma, Takeshi [Frontier Science Organization, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Mostaert, Anika S; Jarvis, Suzanne P [Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Republic of Ireland (Ireland); Serpell, Louise C [Department of Biochemistry, University of Sussex, John Maynard Building, Falmer BN1 9QG (United Kingdom)], E-mail: fukuma@staff.kanazawa-u.ac.jp, E-mail: Anika.Mostaert@ucd.ie, E-mail: L.C.Serpell@sussex.ac.uk, E-mail: Suzi.Jarvis@ucd.ie

    2008-09-24

    We have investigated the surface structure of islet amyloid polypeptide (IAPP) fibrils and {alpha}-synuclein protofibrils in liquid by means of frequency modulation atomic force microscopy (FM-AFM). Angstroem-resolution FM-AFM imaging of isolated macromolecules in liquid is demonstrated for the first time. Individual {beta}-strands aligned perpendicular to the fibril axis with a spacing of 0.5 nm are resolved in FM-AFM images, which confirms cross-{beta} structure of IAPP fibrils in real space. FM-AFM images also reveal the existence of 4 nm periodic domains along the axis of IAPP fibrils. Stripe features with 0.5 nm spacing are also found in images of {alpha}-synuclein protofibrils. However, in contrast to the case for IAPP fibrils, the stripes are oriented 30 deg. from the axis, suggesting the possibility of {beta}-strand alignment in protofibrils different from that in mature fibrils or the regular arrangement of thioflavin T molecules present during the fibril preparation aligned at the surface of the protofibrils.

  2. Revealing molecular-level surface structure of amyloid fibrils in liquid by means of frequency modulation atomic force microscopy

    International Nuclear Information System (INIS)

    Fukuma, Takeshi; Mostaert, Anika S; Jarvis, Suzanne P; Serpell, Louise C

    2008-01-01

    We have investigated the surface structure of islet amyloid polypeptide (IAPP) fibrils and α-synuclein protofibrils in liquid by means of frequency modulation atomic force microscopy (FM-AFM). Angstroem-resolution FM-AFM imaging of isolated macromolecules in liquid is demonstrated for the first time. Individual β-strands aligned perpendicular to the fibril axis with a spacing of 0.5 nm are resolved in FM-AFM images, which confirms cross-β structure of IAPP fibrils in real space. FM-AFM images also reveal the existence of 4 nm periodic domains along the axis of IAPP fibrils. Stripe features with 0.5 nm spacing are also found in images of α-synuclein protofibrils. However, in contrast to the case for IAPP fibrils, the stripes are oriented 30 deg. from the axis, suggesting the possibility of β-strand alignment in protofibrils different from that in mature fibrils or the regular arrangement of thioflavin T molecules present during the fibril preparation aligned at the surface of the protofibrils

  3. Influence of the dynamic Stark effect on long-term frequency stability of a self-oscillating magnetometer with laser-pumped alkali atoms

    Science.gov (United States)

    Baranov, A. A.; Ermak, S. V.; Kulachenkov, N. K.; Petrenko, M. V.; Sagitov, E. A.; Semenov, V. V.

    2017-11-01

    This paper presents the results of investigation Stark shift effect influence on the long-term stability of a dual scheme of quantum magnetometers. Such scheme allows suppressing Stark shift components when a certain pumping light polarization is applied. As a result, long-term stability of a quantum sensor increases. However, when low-frequency (LF) and microwave fields are attached to a single vapor cell a coherence circulation in hyperfine structure of alkali atoms takes place. Physical origin of this effect is associated with the so called “dressed” atom theory, when atom is “dressed” by LF field. It yields in multiphoton absorption and resonance frequency shift. First estimates for this shift based on density matrix evolution formalism are provided in the paper.

  4. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks

    Energy Technology Data Exchange (ETDEWEB)

    François, B. [FEMTO-ST, CNRS, Université de Franche-Comté, 26 chemin de l’Epitaphe, 25030 Besançon (France); INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Calosso, C. E.; Micalizio, S. [INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Abdel Hafiz, M.; Boudot, R. [FEMTO-ST, CNRS, Université de Franche-Comté, 26 chemin de l’Epitaphe, 25030 Besançon (France)

    2015-09-15

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be −109 and −141 dB rad{sup 2}/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is −105 and −138 dB rad{sup 2}/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10{sup −14} for the Cs cell clock and 2 × 10{sup −14} for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10{sup −15} level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

  5. Frequency of malignant tumors during the first two decades of life in the offspring (F1) of atomic bomb survivors

    International Nuclear Information System (INIS)

    Yoshimoto, Yasuhiko; Neel, J.V.; Kato, Hiroo; Mabuchi, Kiyohiko; Schull, W.J.; Soda, Midori; Eto, Ryozo.

    1990-05-01

    The incidence of cancer prior to age 20 has been determined in children born to atomic bomb survivors and to a suitable comparison group. Tumor ascertainment was through death certificates and the tumor registries maintained in Hiroshima and Nagasaki. The rationale for the study stemmed from the evidence that a significant proportion of childhood tumors such as retinoblastoma and Wilms' tumor arise on the basis of a mutant gene inherited from one parent plus a second somatic cell mutation involving the allele of this gene. Gonadal radiation doses were calculated using the recently established DS86 system, supplemented by an ad hoc system for those children whose parents' (one or both) DS86 dose could not be computed but for whom a dose could be developed on the basis of the available information. The total data set consisted of: 1) a cohort of 31,150 liveborn children, one or both of whose parents received ≥ 0.01 Sv of radiation at the time of the A-bombings (an average conjoint gonad exposure of 0.435 Sv), and 2) two suitable comparison groups, totaling 41,066 children. A total of 92 cancer cases at age less than 20 years was confirmed; 49 and 43 cases, respectively, in the 0 Sv and ≥ 0.01 Sv groups. A multiple linear regression analysis revealed no increase in malignancy in the children of exposed parents. However, examination of the data suggested that only 3.0 % to 5.0 % of the tumors of childhood observed in the comparison groups are associated with an inherited genetic predisposition that would be expected to exhibit an altered frequency if the parental mutation rate were increased. These is thus far no confirmation of the positive findings of Nomura in a mouse system. (author)

  6. Comparison of type and frequency of chromosome aberrations by conventional and G-staining methods in Hiroshima atomic bomb survivors

    International Nuclear Information System (INIS)

    Ohtaki, Kazuo; Shimba, Hachiro; Sofuni, Toshio; Awa, A.A.

    1982-07-01

    Somatic chromosomes derived from cultured lymphocytes of 23 atomic bomb survivors of Hiroshima were analyzed to determine the type and frequency of radiation-induced structural aberrations, using in sequence the ordinary staining method (O-method) and the trypsin G-banding method (G-method). Of 896 cells examined, 342 were found to contain induced aberrations, including 31 cells in which the precise identification of the type of aberrations was not possible even by the G-method. The number of chromosome aberrations observed was 376 in the 311 cells where aberrant precise identification was possible. The majority (288 or 76.6%) were intra- or inter-chromosomal symmetric exchanges due to a two-break event, while only 24 were found to be asymmetric exchanges (dicentrics, rings, and interstitial deletions). Further, there were 28 aberrations showing acentric fragments and terminal deletions, and the remaining 36 were complex intra- and inter-chromosomal exchanges involving three or more breaks which result in insertions and double translocations. A comparative karyotype analysis of the same metaphases examined by the sequential 0- And G-methods was carried out independently on 361 aberrations, mostly of the symmetric type. It was found that 78 (21.6%) of the 361 were detected only by the G-method; among these were 14 paracentric inversions, 48 reciprocal interchanges of chromosome segments with either equal length (11) or unequal length (37), 14 minor deletions and 2 complex rearrangements, all of which were nevertheless judged to fall within the normal range of variation by theO-method. In contrast, 25 aberrations detected in O-method chromosomes which were overcontracted or twisted, were shown to have normal banding patterns by the G-method. (author)

  7. Optical frequency measurements of 6s 2S1/2-6p 2P3/2 transition in a 133Cs atomic beam using a femtosecond laser frequency comb

    International Nuclear Information System (INIS)

    Gerginov, V.; Tanner, C.E.; Diddams, S.; Bartels, A.; Hollberg, L.

    2004-01-01

    Optical frequencies of the hyperfine components of the D 2 line in 133 Cs are determined using high-resolution spectroscopy and a femtosecond laser frequency comb. A narrow-linewidth probe laser excites the 6s 2 S 1/2 (F=3,4)→6p 2 P 3/2 (F=2,3,4,5) transition in a highly collimated atomic beam. Fluorescence spectra are taken by scanning the laser frequency over the excited-state hyperfine structure. The laser optical frequency is referenced to a Cs fountain clock via a reference laser and a femtosecond laser frequency comb. A retroreflected laser beam is used to estimate and minimize the Doppler shift due to misalignment between the probe laser and the atomic beam. We achieve an angular resolution on the order of 5x10 -6 rad. The final uncertainties (∼±5 kHz) in the frequencies of the optical transitions are a factor of 20 better than previous results [T. Udem et al., Phys. Rev. A 62, 031801 (2000).]. We find the centroid of the 6s 2 S 1/2 →6p 2 P 3/2 transition to be f D2 =351 725 718.4744(51) MHz

  8. Narrow Line Cooling of 88Sr Atoms in the Magneto-optical Trap for Precision Frequency Standard

    Science.gov (United States)

    Strelkin, S. A.; Galyshev, A. A.; Berdasov, O. I.; Gribov, A. Yu.; Sutyrin, D. V.; Khabarova, K. Yu.; Kolachevsky, N. N.; Slyusarev, S. N.

    We report on our progress toward the realization of a Strontium optical lattice clock, which is under development at VNIIFTRI as a part of GLONASS program. We've prepared the narrow line width laser system for secondary cooling of 88Sr atoms which allows us to reach atom cloud temperature below 3 μK after second cooling stage.

  9. Frequencies of micro-nucleated lymphocytes and Epstein-Barr virus contamination in Altay region residents living near the Semipalatinsk atomic testing ground

    International Nuclear Information System (INIS)

    Ilyinskikh, N.N.; Ilyinskikh, E.N.; Yurkin, A.Yu.; Ilyinskikh, I.N.

    2003-01-01

    We have assessed frequencies of micro-nucleated lymphocytes in 3036 individuals living in 16 settlements in the west of the Altay region. Among the settlements the majority of individuals with significantly high frequencies of micro-nucleated lymphocytes were detected in settlements adjacent to the Semipalatinsk atomic testing ground (SATG). The most considerable genome instability was found in the individuals born in the period of intensive testing on the SATG (from 1949 to 1962). Moreover, we have determined that the residents of the settlements adjacent to the SATG have significantly high levels of antibodies to potentially oncogenic Epstein-Barr virus besides high frequencies of micro-nucleated lymphocytes. The considerable Epstein-Barr virus contamination among the residents in the radiation polluted zone around the SATG was supposed to be caused by immunodeficiency disorders in these individuals and induce high frequencies of micro-nucleated cells. (author)

  10. Characterisation of the membrane affinity of an isoniazide peptide conjugate by tensiometry, atomic force microscopy and sum-frequency vibrational spectroscopy, using a phospholipid Langmuir monolayer model.

    Science.gov (United States)

    Hill, Katalin; Pénzes, Csanád Botond; Schnöller, Donát; Horváti, Kata; Bosze, Szilvia; Hudecz, Ferenc; Keszthelyi, Tamás; Kiss, Eva

    2010-10-07

    Tensiometry, sum-frequency vibrational spectroscopy, and atomic force microscopy were employed to assess the cell penetration ability of a peptide conjugate of the antituberculotic agent isoniazide. Isoniazide was conjugated to peptide (91)SEFAYGSFVRTVSLPV(106), a functional T-cell epitope of the immunodominant 16 kDa protein of Mycobacterium tuberculosis. As a simple but versatile model of the cell membrane a phospholipid Langmuir monolayer at the liquid/air interface was used. Changes induced in the structure of the phospholipid monolayer by injection of the peptide conjugate into the subphase were followed by tensiometry and sum-frequency vibrational spectroscopy. The drug penetrated lipid films were transferred to a solid support by the Langmuir-Blodgett technique, and their structures were characterized by atomic force microscopy. Peptide conjugation was found to strongly enhance the cell penetration ability of isoniazide.

  11. Bimodal atomic force microscopy driving the higher eigenmode in frequency-modulation mode: Implementation, advantages, disadvantages and comparison to the open-loop case.

    Science.gov (United States)

    Ebeling, Daniel; Solares, Santiago D

    2013-01-01

    We present an overview of the bimodal amplitude-frequency-modulation (AM-FM) imaging mode of atomic force microscopy (AFM), whereby the fundamental eigenmode is driven by using the amplitude-modulation technique (AM-AFM) while a higher eigenmode is driven by using either the constant-excitation or the constant-amplitude variant of the frequency-modulation (FM-AFM) technique. We also offer a comparison to the original bimodal AFM method, in which the higher eigenmode is driven with constant frequency and constant excitation amplitude. General as well as particular characteristics of the different driving schemes are highlighted from theoretical and experimental points of view, revealing the advantages and disadvantages of each. This study provides information and guidelines that can be useful in selecting the most appropriate operation mode to characterize different samples in the most efficient and reliable way.

  12. Controladoria e eficiência no setor público

    Directory of Open Access Journals (Sweden)

    Francisco Apoliano Albuquerque

    2015-12-01

    Full Text Available A controladoria é relevante para apoiar e orientar os gestores de recursos públicos quanto à melhor e mais eficiente forma de aplicação do gasto público. Na seara da gestão pública, a controladoria deve funcionar como órgão de linha e/ou de staff dentro da estrutura organizacional, atuando de maneira preventiva, visando à otimização da aplicação dos recursos e correção de rotas quando forem detectados desvios nos objetivos estratégicos. Assim, este artigo tem como objetivo abordar a controladoria sob o enfoque de comprovar a legalidade e avaliar os resultados quanto à eficiência e à efetividade da gestão orçamentária, financeira e patrimonial nos órgãos da administração pública. Para tanto, a metodologia utilizada na pesquisa foi de caráter eminentemente bibliográfico, uma vez que a bibliografia constitui um passo inicial na construção efetiva do protocolo de investigação.

  13. Radio-frequency heating and neutral atom transport in a fluid-magnetohydrodynamic treatment of burning tokamak plasmas

    International Nuclear Information System (INIS)

    Conn, R.W.; Mau, T.K.; Prinja, A.K.

    1983-01-01

    A physical model for the space and time evolution of the primary parameters of ordinary and burning tokamak plasmas is described by employing a fluid plasma treatment coupled to a magnetohydrodynamic equilibrium description, the solution to the appropriate Maxwell equations, and the solution of the linear transport equation describing neutral atom transport in plasmas. The specific problems of plasma heating by ion cyclotron radiofrequency (ICRF) waves and neutral atom transport in the plasma edge and in complicated geometrical components such as divertor channels or pumped limiter structures are analyzed. A theoretical, onedimensional slab model of ICRF heating at ω = 2ω/SUB cD/ is developed and applied to determine the space-time response of tokamak plasmas. Generally, strong single-pass absorption is found for high-density, high (β) plasmas using a low k 11 spectrum (0.05 to 0.1 cm -1 ) although for (β > 1%, electron Landau damping becomes important. Deterministic and Monte Carlo methods to solve the neutral atom transport problem are described. Specific application to determine the spectrum of neutral atoms emerging from the duct of a pump limiter shows it to be hard (mean energy > 20 eV), indicating very incomplete energy thermalization. Uncertainties are identified in the overall problem of dynamic burning plasma analysis caused by the complexity of the problem itself and by uncertainties in fundamental areas such as plasma transport coefficients, stability, and plasma edge physics

  14. Definitions of Frequency and Timing Terms, Satellite Navigation and Timing Systems, and the Behavior and Analyses of Precision Crystal and Atomic Frequency Standards and their Characteristics

    Science.gov (United States)

    2009-05-01

    expected value of a measurement or property when operating in a normal expected environment. For example, the nominal value of a 51 ohm, 20% resistor ...operating at room temperature is 51 ohms. However, the actual resistance of any single 51 ohm, 20% resistor may be any value between 46 and 56...NIST Technical Note 1337, March 1990. 6. Piezo Crystal Company, (September 1990). Frequency Sources That Set the Standard. RCC Document 214-09

  15. High-contrast sub-Doppler absorption spikes in a hot atomic vapor cell exposed to a dual-frequency laser field

    International Nuclear Information System (INIS)

    Abdel Hafiz, Moustafa; Coget, Grégoire; Boudot, Rodolphe; Brazhnikov, Denis; Taichenachev, Alexei; Yudin, Valeriy; De Clercq, Emeric

    2017-01-01

    The saturated absorption technique is an elegant method widely used in atomic and molecular physics for high-resolution spectroscopy, laser frequency standards and metrology purposes. We have recently discovered that a saturated absorption scheme with a dual-frequency laser can lead to a significant sign reversal of the usual Doppler-free dip, yielding a deep enhanced-absorption spike. In this paper, we report detailed experimental investigations of this phenomenon, together with a full in-depth theoretical description. It is shown that several physical effects can support or oppose the formation of the high-contrast central spike in the absorption profile. The physical conditions for which all these effects act constructively and result in very bright Doppler-free resonances are revealed. Apart from their theoretical interest, results obtained in this manuscript are of great interest for laser spectroscopy and laser frequency stabilization purposes, with applications in laser cooling, matter-wave sensors, atomic clocks or quantum optics. (paper)

  16. Determination of frequencies of atomic oscillations along the fourth order symmetry axis in indium arsenide according to thermal diffusion scattering of X-rays

    International Nuclear Information System (INIS)

    Orlova, N.S.

    1978-01-01

    Intensity of diffusion scattering of X-rays from the plane of a monocrystal of indium arsenide has been measured on the monochromatized CuKsub(α)-radiation. The samples are made of Cl indium arsenide monocrystal of the n-type with the 1x10 18 cm -3 concentration of carriers in the form of a plate with the polished parallel cut-off with the +-5' accuracy. The investigations have been carried out on the URS-5 IM X-ray diffractometer at room temperature in vacuum. Intensities of thermal diffusion scattering of the second order have been calculated by the two-atomic chain model with different mass and four interaction paramaters. Based upon the analysis of intensity of single-phonon diffusion scattering the curves of frequencies of atomic oscillations along the direction [100] have been determined. The values of frequencies obtained experimentally on the thermal diffusion scattering of X-rays are in a satisfactory agreement with the calculated data. The frequencies obtained are compared with the results of calculation and the analysis of multiphonon spectra of IR-absorption made elsewhere

  17. Precision measurement of the 1S ground-state Lamb shift in atomic hydrogen and deuterium by frequency comparison

    International Nuclear Information System (INIS)

    Weitz, M.; Huber, A.; Schmidt-Kaler, F.; Leibfried, D.; Vassen, W.; Zimmermann, C.; Pachucki, K.; Haensch, T.W.; Julien, L.; Biraben, F.

    1995-01-01

    We have measured the hydrogen and deuterium 1S Lamb shift by direct optical frequency comparison of the 1S-2S and 2S-4S/4D two-photon transitions. Our result of 8172.874(60) MHz for the 1S Lamb shift in hydrogen is in agreement with the theoretical value of 8172.802(40) MHz. For the 1S Lamb shift in deuterium, we obtain a value of 8183.807(78) MHz, from which we derive a deuteron matter radium of 1.945(28) fm. The precision of our value for the 1S Lamb shift has surpassed that of radio frequency measurements of the 2S-2P Lamb shift. By comparison with a recent absolute measurement of the hydrogen 1S-2S transition frequency, we deduce a value for the Rydberg constant R ∞ =109 737.315 684 9(30) cm -1

  18. Dissolution Processes at Step Edges of Calcite in Water Investigated by High-Speed Frequency Modulation Atomic Force Microscopy and Simulation.

    Science.gov (United States)

    Miyata, Kazuki; Tracey, John; Miyazawa, Keisuke; Haapasilta, Ville; Spijker, Peter; Kawagoe, Yuta; Foster, Adam S; Tsukamoto, Katsuo; Fukuma, Takeshi

    2017-07-12

    The microscopic understanding of the crystal growth and dissolution processes have been greatly advanced by the direct imaging of nanoscale step flows by atomic force microscopy (AFM), optical interferometry, and X-ray microscopy. However, one of the most fundamental events that govern their kinetics, namely, atomistic events at the step edges, have not been well understood. In this study, we have developed high-speed frequency modulation AFM (FM-AFM) and enabled true atomic-resolution imaging in liquid at ∼1 s/frame, which is ∼50 times faster than the conventional FM-AFM. With the developed AFM, we have directly imaged subnanometer-scale surface structures around the moving step edges of calcite during its dissolution in water. The obtained images reveal that the transition region with typical width of a few nanometers is formed along the step edges. Building upon insight in previous studies, our simulations suggest that the transition region is most likely to be a Ca(OH) 2 monolayer formed as an intermediate state in the dissolution process. On the basis of this finding, we improve our understanding of the atomistic dissolution model of calcite in water. These results open up a wide range of future applications of the high-speed FM-AFM to the studies on various dynamic processes at solid-liquid interfaces with true atomic resolution.

  19. Atomic force microscopy indentation of fluorocarbon thin films fabricated by plasma enhanced chemical deposition at low radio frequency power

    International Nuclear Information System (INIS)

    Sirghi, L.; Ruiz, A.; Colpo, P.; Rossi, F.

    2009-01-01

    Atomic force microscopy (AFM) indentation technique is used for characterization of mechanical properties of fluorocarbon (CF x ) thin films obtained from C 4 F 8 gas by plasma enhanced chemical vapour deposition at low r.f. power (5-30 W) and d.c. bias potential (10-80 V). This particular deposition method renders films with good hydrophobic property and high plastic compliance. Commercially available AFM probes with stiff cantilevers (10-20 N/m) and silicon sharpened tips (tip radius < 10 nm) are used for indentations and imaging of the resulted indentation imprints. Force depth curves and imprint characteristics are used for determination of film hardness, elasticity modulus and plasticity index. The measurements show that the decrease of the discharge power results in deposition of films with decreased hardness and stiffness and increased plasticity index. Nanolithography based on AFM indentation is demonstrated on thin films (thickness of 40 nm) with good plastic compliance.

  20. Atomic frequency reference at 1033 nm for ytterbium (Yb)-doped fiber lasers and applications exploiting a rubidium (Rb) 5S_1/2 to 4D_5/2 one-colour two-photon transition

    Science.gov (United States)

    Roy, Ritayan; Condylis, Paul C.; Johnathan, Yik Jinen; Hessmo, Björn

    2017-04-01

    We demonstrate a two-photon transition of rubidium (Rb) atoms from the ground state (5$S_{1/2}$) to the excited state (4$D_{5/2}$), using a home-built ytterbium (Yb)-doped fiber amplifier at 1033 nm. This is the first demonstration of an atomic frequency reference at 1033 nm as well as of a one-colour two-photon transition for the above energy levels. A simple optical setup is presented for the two-photon transition fluorescence spectroscopy, which is useful for frequency stabilization for a broad class of lasers. This spectroscopy has potential applications in the fiber laser industry as a frequency reference, particularly for the Yb-doped fiber lasers. This two-photon transition also has applications in atomic physics as a background- free high- resolution atom detection and for quantum communication, which is outlined in this article.

  1. A miniaturized, high frequency mechanical scanner for high speed atomic force microscope using suspension on dynamically determined points

    Energy Technology Data Exchange (ETDEWEB)

    Herfst, Rodolf; Dekker, Bert; Witvoet, Gert; Crowcombe, Will; Lange, Dorus de [Department of Optomechatronics, Netherlands Organization for Applied Scientific Research, TNO, Delft (Netherlands); Sadeghian, Hamed, E-mail: hamed.sadeghianmarnani@tno.nl, E-mail: h.sadeghianmarnani@tudelft.nl [Department of Optomechatronics, Netherlands Organization for Applied Scientific Research, TNO, Delft (Netherlands); Department of Precision and Microsystems Engineering, Delft University of Technology, Delft (Netherlands)

    2015-11-15

    One of the major limitations in the speed of the atomic force microscope (AFM) is the bandwidth of the mechanical scanning stage, especially in the vertical (z) direction. According to the design principles of “light and stiff” and “static determinacy,” the bandwidth of the mechanical scanner is limited by the first eigenfrequency of the AFM head in case of tip scanning and by the sample stage in terms of sample scanning. Due to stringent requirements of the system, simply pushing the first eigenfrequency to an ever higher value has reached its limitation. We have developed a miniaturized, high speed AFM scanner in which the dynamics of the z-scanning stage are made insensitive to its surrounding dynamics via suspension of it on specific dynamically determined points. This resulted in a mechanical bandwidth as high as that of the z-actuator (50 kHz) while remaining insensitive to the dynamics of its base and surroundings. The scanner allows a practical z scan range of 2.1 μm. We have demonstrated the applicability of the scanner to the high speed scanning of nanostructures.

  2. Legal Time of the Republic of Colombia and its international traceability using the Cesium Atomic Clock - Time and Frequency National Standard

    Science.gov (United States)

    Hernández Forero, Liz Catherine; Bahamón Cortés, Nelson

    2017-06-01

    Around the world, there are different providers of timestamp (mobile, radio or television operators, satellites of the GPS network, astronomical measurements, etc.), however, the source of the legal time for a country is either the national metrology institute or another designated laboratory. This activity requires a time standard based on an atomic time scale. The International Bureau of Weights and Measures (BIPM) calculates a weighted average of the time kept in more than 60 nations and produces a single international time scale, called Coordinated Universal Time (UTC). This article presents the current time scale that generates Legal Time for the Republic of Colombia produced by the Instituto Nacional de Metrología (INM) using the time and frequency national standard, a cesium atomic oscillator. It also illustrates how important it is for the academic, scientific and industrial communities, as well as the general public, to be synchronized with this time scale, which is traceable to the International System (SI) of units, through international comparisons that are made in real time.

  3. Bremsstrahlung in atom-atom collisions

    International Nuclear Information System (INIS)

    Amus'ya, M.Y.; Kuchiev, M.Y.; Solov'ev, A.V.

    1985-01-01

    It is shown that in the collision of a fast atom with a target atom when the frequencies are on the order of the potentials or higher, there arises bremsstrahlung comparable in intensity with the bremsstrahlung emitted by an electron with the same velocity in the field of the target atom. The mechanism by which bremsstrahlung is produced in atom-atom collisions is elucidated. Results of specific calculations of the bremsstrahlung spectra are given for α particles and helium atoms colliding with xenon

  4. Photoionization of resonantly driven atomic states by an extreme ultraviolet-free-electron laser: intensity dependence and renormalization of Rabi frequencies

    International Nuclear Information System (INIS)

    Kaiser, B; Brand, A; Glässl, M; Vagov, A; Axt, V M; Pietsch, U

    2013-01-01

    We analyze theoretically the high intensity photoionization dynamics of a system with two atomic states resonantly coupled by coherent extreme ultraviolet laser radiation that also gives rise to the ionization. The ground state occupation of such a system is shown to exhibit damped Rabi oscillations. The corresponding ionization, which is responsible for the damping, scales almost linearly with the field intensity when the pulse length exceeds the Rabi period. For shorter pulses a quadratic scaling is found. The Rabi frequency is shifted compared to its value for an isolated two-level system. The shift increases with excitation intensity and can acquire a high percentage of the unrenormalized frequency at high intensities. Analytical results obtained within a simplified solvable model demonstrate that the damping and the shift both result from the coupling of the discrete states to the ionization continuum and are therefore closely related. Numerical simulations for a two-electron system reveal at high intensities the importance of off-resonant ionization channels. (paper)

  5. Eficiência reprodutiva no amendoim cultivado (Arachis hypogaea L. Reproductive efficiency in the peanut (Arachis hypogaea L.

    Directory of Open Access Journals (Sweden)

    Cândida H. T. Mendes Conagin

    1960-01-01

    Full Text Available Cinco variedades de amendoim, abrangendo os três tipos vegetativos conhecidos, foram comparadas quanto à sua eficiência reprodutiva. Para conhecer o resultado final de porcentagem de frutos e sementes, foram estudadas a quantidade de flôres, a duração e as oscilações do florescimento; a formação de frutos e sementes também foi estudada com detalhes. Tendo variado o número de plantas observadas nos diversos itens, em diversos anos, tôdas as informações foram referidas a "uma planta" para poderem ser comparadas quando necessário. O período útil de florescimento dura as dez semanas medianas do ciclo vegetativo da planta, o máximo de flôres sendo atingido na 10.ª semana dêsse ciclo. Há, entretanto, a observar, que as variedades eretas são mais precoces do que as de porte decumbente; o florescimento apresenta bruscas oscilações diárias. É a variedade Tatuí a que produz mais flôres por planta, tendo, entretanto, a mais baixa eficiência reprodutiva. As outras variedades têm eficiência mais alta, mas, mesmo assim, ela é surpreendentemente baixa, em se tratando de uma planta de grande florescimento como é o amendoim. As informações obtidas nestes ensaios são fundamentais para qualquer trabalho de melhoramento por hibridação e já estão sendo utilizadas nos atuais cruzamentos, feitos pela Seção de Citologia.A study of the reproductive efficiency of five agronomical varieties of peanut was made. Determinations were made of fruit and seed percentages in relation to number of flowers procured, length of flowering period, alternation of high and low daily flower frequencies, and number of flowers which had no chance to become fruit?. Data obtained supported lhe following conclusions: (a Varieties of the erect vegetative type were early; they began and ended their vegetative am! flowering cycles before those of the decumbent type. (b The flowering curves showed an abrupt alternation of high and low frequencies. (c The

  6. Realization of a frequency standard at 778 nm: absolute frequency measurement of the 2S-8S/D transitions in hydrogen and deuterium and determination of the Rydberg constant; Realisation d'un etalon de frequence a 778 nm: mesure absolue des frequences 2S-8S/D des atomes d'hydrogene et de deuterium et determination de la constante de rydberg

    Energy Technology Data Exchange (ETDEWEB)

    Beauvoir, B. de

    1996-12-15

    The purpose of this work is to design a 778 nm standard laser for performing an absolute measurement of 2S-8S/D frequencies of hydrogen and deuterium atoms. This frequency calibration is based on a 5S-5D two-photon transition of the rubidium atom. Metrological performance of this laser is 10 times as good as that of He-Ne laser calibrated on iodine. It has been shown that the passage of a laser radiation through an optic fiber does not deteriorate its metrological properties. 2S-8S/8D transitions have been excited in an atomic jet by a titanium-sapphire laser. Spurious effects can shift and broaden lines. In order to prevent these effects, a theoretical line has been shaped and adjusted on experimental signals. The frequency comparison between the excitation laser and the standard laser has led to the measurement of the absolute frequency of the line concerned. The value of the Rydberg constant has been deduced: R{sub {infinity}} = 109737.3156859 (10) cm{sup -1}. The comparison of experimental data between deuterium and hydrogen has allowed us to determine the value of the Lamb shift of the 2S state of deuterium: L(2S-2P) = 1059,230 (9) MHz.

  7. The molecular-scale arrangement and mechanical strength of phospholipid/cholesterol mixed bilayers investigated by frequency modulation atomic force microscopy in liquid

    International Nuclear Information System (INIS)

    Asakawa, Hitoshi; Fukuma, Takeshi

    2009-01-01

    Cholesterols play key roles in controlling molecular fluidity in a biological membrane, yet little is known about their molecular-scale arrangements in real space. In this study, we have directly imaged lipid-cholesterol complexes in a model biological membrane consisting of dipalmitoylphosphatidylcholine (DPPC) and cholesterols by frequency modulation atomic force microscopy (FM-AFM) in phosphate buffer solution. FM-AFM images of a DPPC/cholesterol bilayer in the liquid-ordered phase showed higher energy dissipation values compared to those measured on a nanoscale DPPC domain in the gel phase, reflecting the increased molecular fluidity due to the insertion of cholesterols. Molecular-resolution FM-AFM images of a DPPC/cholesterol bilayer revealed the existence of a rhombic molecular arrangement (lattice constants: a = 0.46 nm, b = 0.71 nm) consisting of alternating rows of DPPC and cholesterols as well as the increased defect density and reduced molecular ordering. The mechanical strength of a DPPC/cholesterol bilayer was quantitatively evaluated by measuring a loading force required to penetrate the membrane with an AFM tip. The result revealed the significant decrease of mechanical strength upon insertion of cholesterols. Based on the molecular-scale arrangement found in this study, we propose a model to explain the reduced mechanical strength in relation to the formation of lipid-ion networks.

  8. The molecular-scale arrangement and mechanical strength of phospholipid/cholesterol mixed bilayers investigated by frequency modulation atomic force microscopy in liquid

    Energy Technology Data Exchange (ETDEWEB)

    Asakawa, Hitoshi; Fukuma, Takeshi [Frontier Science Organization, Kanazawa University, Kakuma-machi, 920-1192 Kanazawa (Japan)], E-mail: hi_asa@staff.kanazawa-u.ac.jp, E-mail: fukuma@staff.kanazawa-u.ac.jp

    2009-07-01

    Cholesterols play key roles in controlling molecular fluidity in a biological membrane, yet little is known about their molecular-scale arrangements in real space. In this study, we have directly imaged lipid-cholesterol complexes in a model biological membrane consisting of dipalmitoylphosphatidylcholine (DPPC) and cholesterols by frequency modulation atomic force microscopy (FM-AFM) in phosphate buffer solution. FM-AFM images of a DPPC/cholesterol bilayer in the liquid-ordered phase showed higher energy dissipation values compared to those measured on a nanoscale DPPC domain in the gel phase, reflecting the increased molecular fluidity due to the insertion of cholesterols. Molecular-resolution FM-AFM images of a DPPC/cholesterol bilayer revealed the existence of a rhombic molecular arrangement (lattice constants: a = 0.46 nm, b = 0.71 nm) consisting of alternating rows of DPPC and cholesterols as well as the increased defect density and reduced molecular ordering. The mechanical strength of a DPPC/cholesterol bilayer was quantitatively evaluated by measuring a loading force required to penetrate the membrane with an AFM tip. The result revealed the significant decrease of mechanical strength upon insertion of cholesterols. Based on the molecular-scale arrangement found in this study, we propose a model to explain the reduced mechanical strength in relation to the formation of lipid-ion networks.

  9. Phase transition behaviors of the supported DPPC bilayer investigated by sum frequency generation (SFG) vibrational spectroscopy and atomic force microscopy (AFM).

    Science.gov (United States)

    Wu, Heng-Liang; Tong, Yujin; Peng, Qiling; Li, Na; Ye, Shen

    2016-01-21

    The phase transition behaviors of a supported bilayer of dipalmitoylphosphatidyl-choline (DPPC) have been systematically evaluated by in situ sum frequency generation (SFG) vibrational spectroscopy and atomic force microscopy (AFM). By using an asymmetric bilayer composed of per-deuterated and per-protonated monolayers, i.e., DPPC-d75/DPPC and a symmetric bilayer of DPPC/DPPC, we were able to probe the molecular structural changes during the phase transition process of the lipid bilayer by SFG spectroscopy. It was found that the DPPC bilayer is sequentially melted from the top (adjacent to the solution) to bottom leaflet (adjacent to the substrate) over a wide temperature range. The conformational ordering of the supported bilayer does not decrease (even slightly increases) during the phase transition process. The conformational defects in the bilayer can be removed after the complete melting process. The phase transition enthalpy for the bottom leaflet was found to be approximately three times greater than that for the top leaflet, indicating a strong interaction of the lipids with the substrate. The present SFG and AFM observations revealed similar temperature dependent profiles. Based on these results, the temperature-induced structural changes in the supported lipid bilayer during its phase transition process are discussed in comparison with previous studies.

  10. Análise da eficiência dos sistemas estruturais para edifícios em concreto

    OpenAIRE

    Silva, Gildemir; Prata, Bruno; Albuquerque, Augusto

    2018-01-01

    Resumo Nos últimos anos houve uma evolução dos métodos construtivos empregados no Brasil, principalmente no que se refere às estruturas de concreto. Embora a literatura sobre eficiência na construção civil seja vasta, a proposição de métodos não paramétricos para a análise de eficiência de processos construtivos ainda é bastante limitada. Este trabalho apresenta um modelo para análise de eficiência baseado na técnica Data Envelopment Analysis (DEA) para uma análise comparada da eficiência dos...

  11. O FUNDEF e a eficiência na provisão municipal de ensino fundamental

    Directory of Open Access Journals (Sweden)

    Marco Túlio Aniceto França

    2016-03-01

    Full Text Available Resumo O artigo estima a relação entre a implantação do FUNDEF (Fundo de Manutenção e de Desenvolvimento do Ensino Fundamental e de Valorização do Magistério e a eficiência na gestão municipal do ensino no ano de 2007. Para o cálculo da eficiência, primeiro empregou-se o modelo SBM (slacks basedmeasure com as características discricionárias. posteriormente, por meio de um modelo Tobit, controlamos o efeito das variáveis não discricionárias. A estimação da relação entre o FUNDEF e a eficiência foi através de modelos de seleção em observáveis. Os dados foram oriundos do Censo Escolar, Prova Brasil Finbra (Finanças do Brasil. Os resultados mostram uma melhoria de eficiência a partir de oito anos de adoção do programa e os estímulos corretos ao processo de descentralização. O trabalho conclui que a criação de uma estrutura de gestão municipal do ensino fundamental eficiente demanda tempo e abre boas perspectivas para os resultados esperados com o FUNDEB (Fundo de Manutenção e Desenvolvimento da Educação Básica e de Valorização dos Profissionais da Educação.

  12. Radio frequency plasma power dependence of the moisture permeation barrier characteristics of Al2O3 films deposited by remote plasma atomic layer deposition

    International Nuclear Information System (INIS)

    Jung, Hyunsoo; Choi, Hagyoung; Lee, Sanghun; Jeon, Heeyoung; Jeon, Hyeongtag

    2013-01-01

    In the present study, we investigated the gas and moisture permeation barrier properties of Al 2 O 3 films deposited on polyethersulfone films (PES) by capacitively coupled plasma (CCP) type Remote Plasma Atomic Layer Deposition (RPALD) at Radio Frequency (RF) plasma powers ranging from 100 W to 400 W in 100 W increments using Trimethylaluminum [TMA, Al(CH 3 ) 3 ] as the Al source and O 2 plasma as the reactant. To study the gas and moisture permeation barrier properties of 100-nm-thick Al 2 O 3 at various plasma powers, the Water Vapor Transmission Rate (WVTR) was measured using an electrical Ca degradation test. WVTR decreased as plasma power increased with WVTR values for 400 W and 100 W of 2.6 × 10 −4 gm −2 day −1 and 1.2 × 10 −3 gm −2 day −1 , respectively. The trends for life time, Al-O and O-H bond, density, and stoichiometry were similar to that of WVTR with improvement associated with increasing plasma power. Further, among plasma power ranging from 100 W to 400 W, the highest power of 400 W resulted in the best moisture permeation barrier properties. This result was attributed to differences in volume and amount of ion and radical fluxes, to join the ALD process, generated by O 2 plasma as the plasma power changed during ALD process, which was determined using a plasma diagnosis technique called the Floating Harmonic Method (FHM). Plasma diagnosis by FHM revealed an increase in ion flux with increasing plasma power. With respect to the ALD process, our results indicated that higher plasma power generated increased ion and radical flux compared with lower plasma power. Thus, a higher plasma power provides the best gas and moisture permeation barrier properties

  13. Cross-Sectional Imaging of Boundary Lubrication Layer Formed by Fatty Acid by Means of Frequency-Modulation Atomic Force Microscopy.

    Science.gov (United States)

    Hirayama, Tomoko; Kawamura, Ryota; Fujino, Keita; Matsuoka, Takashi; Komiya, Hiroshi; Onishi, Hiroshi

    2017-10-10

    To observe in situ the adsorption of fatty acid onto metal surfaces, cross-sectional images of the adsorption layer were acquired by frequency-modulation atomic force microscopy (FM-AFM). Hexadecane and palmitic acid were used as the base oil and typical fatty acid, respectively. A Cu-coated silicon wafer was prepared as the target substrate. The solvation structure formed by hexadecane molecules at the interface between the Cu substrate and the hexadecane was observed, and the layer pitch was found to be about 0.6 nm, which corresponds to the height of hexadecane molecules. This demonstrates that hexadecane molecules physically adsorbed onto the surface due to van der Waals forces with lying orientation because hexadecane is a nonpolar hydrocarbon. When hexadecane with palmitic acid was put on the Cu substrate instead of pure hexadecane, an adsorption layer of palmitic acid was observed at the interface. The layer pitch was about 2.5-2.8 nm, which matches the chain length of palmitic acid molecules well. This indicates that the original adsorption layer was monolayer or single bilayer in the local area. In addition, a cross-sectional image captured 1 h after observation started to reveal that the adsorbed additive layer gradually grew up to be thicker than about 20 nm due to an external stimulus, such as cantilever oscillation. This is the first report of in situ observation of an adsorbed layer by FM-AFM in the tribology field and demonstrates that FM-AFM is useful for clarifying the actual boundary lubrication mechanism.

  14. Immune responses to epstein-barr virus in atomic bomb survivors: Study of precursor frequency of cytotoxic lymphocytes and titer levels of anti-Epstein-Barr virus-related antibodies

    International Nuclear Information System (INIS)

    Kusunoki, Yoichiro; Kyoizumi, Seishi; Saito, Mayumi; Ozaki, Kyoko; Hirai, Yuko; Akiyama, Mitoshi; Fukuda, Yasuko; Huang, Hua

    1994-01-01

    Precursor frequencies of cytotoxic lymphocytes to autologous Epstein-Barr virus-transformed B cells and serum titers of anti-Epstein-Barr virus-related antibodies were measured in 68 atomic bomb survivors to clarify the immune mechanism controlling Epstein-Barr virus infection. The precursor frequency was negatively correlated with the titer of anti-early antigen lgG, which is probably produced at the stage of viral reactivation. A positive correlation between the precursor frequency and titer of anti-Epstein-Barr virus-associated nuclear antigen antibody was also observed, indicating that the precursor frequency reflects the degree of in vivo destruction by T cells of the virus-infected cells. These results suggest that T-cell memory specific to Epstein-Barr virus keeps the virus under control and that the precursor frequency assay is useful for the evaluation of immune responses to Epstein-Barr virus. However, no significant effect of atomic bomb radiation on the precursor frequency was observed in the present study, probably due to the limited number of participants. 24 refs., 4 figs., 2 tabs

  15. Immune responses to epstein-barr virus in atomic bomb survivors: Study of precursor frequency of cytotoxic lymphocytes and titer levels of anti-Epstein-Barr virus-related antibodies

    Energy Technology Data Exchange (ETDEWEB)

    Kusunoki, Yoichiro; Kyoizumi, Seishi; Saito, Mayumi; Ozaki, Kyoko; Hirai, Yuko; Akiyama, Mitoshi (Radiation Effects Research Foundation, Hiroshima (Japan)); Fukuda, Yasuko (Radiation Effects Research Foundation, Hiroshima (Japan) Children' s Hospital Medical Center of Northern California, Oakland, CA (United States)); Huang, Hua (Radiation Effects Research Foundation, Hiroshima (Japan) Univ. of Wisconsin, Madison, WI (United States))

    1994-04-01

    Precursor frequencies of cytotoxic lymphocytes to autologous Epstein-Barr virus-transformed B cells and serum titers of anti-Epstein-Barr virus-related antibodies were measured in 68 atomic bomb survivors to clarify the immune mechanism controlling Epstein-Barr virus infection. The precursor frequency was negatively correlated with the titer of anti-early antigen lgG, which is probably produced at the stage of viral reactivation. A positive correlation between the precursor frequency and titer of anti-Epstein-Barr virus-associated nuclear antigen antibody was also observed, indicating that the precursor frequency reflects the degree of in vivo destruction by T cells of the virus-infected cells. These results suggest that T-cell memory specific to Epstein-Barr virus keeps the virus under control and that the precursor frequency assay is useful for the evaluation of immune responses to Epstein-Barr virus. However, no significant effect of atomic bomb radiation on the precursor frequency was observed in the present study, probably due to the limited number of participants. 24 refs., 4 figs., 2 tabs.

  16. Eficiência Produtiva Regional da Agricultura Brasileira: uma análise de fronteira estocástica

    Directory of Open Access Journals (Sweden)

    Clauber Eduardo Marchezan Scherer

    Full Text Available Resumo: O objetivo deste estudo é analisar a eficiência produtiva da agricultura em escala microrregional usando técnicas de estimação de fronteiras de produção estocásticas e análise exploratória de dados espaciais. As estimações foram feitas para as lavouras permanentes e temporárias separadamente com dados do Censo Agropecuário 2006. Os resultados da equação de produção mostram que os fatores produtivos área de terra e trabalho representam ganhos de produtividade para essas lavouras ligados aos retornos crescentes de escala e à intensidade tecnológica. Os resultados também indicam que a relação entre eficiência e especialização é positiva nas lavouras permanentes e negativa nas lavouras temporárias. Fatores geográficos relacionados com precipitações, temperatura e biomas se mostraram mais relevantes para explicar os diferenciais regionais de eficiência das lavouras temporárias. A análise espacial aplicada à lavoura permanente identificou clusters de alta eficiência nas regiões Nordeste e Sul e um núcleo de baixa eficiência na região Norte. Para as lavouras temporárias, destacam-se poucos clusters de alta eficiência situados nas regiões Nordeste e Sudeste e áreas extensas de baixa eficiência situadas predominantemente no Nordeste e Norte do Brasil.

  17. Spectral anomalies of the effect of light-induced drift of caesium atoms caused by the velocity dependence of transport collision frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Parkhomenko, A I [Institute of Automation and Electrometry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation); Shalagin, A M [Novosibirsk State University, Novosibirsk (Russian Federation)

    2014-10-31

    The spectral features of the light-induced drift (LID) velocity of caesium atoms in inert buffer gases are studied theoretically. A strong temperature dependence of the spectral LID line shape of Cs atoms in Ar or Kr atmosphere in the vicinity of T ∼ 1000 K is predicted. It is shown that the anomalous LID of Cs atoms in binary buffer mixtures of two different inert gases can be observed at virtually any (including ambient) temperature, depending on the content of the components in these mixtures. The results obtained make it possible to precisely test the interatomic interaction potentials in the experiments on the anomalous LID. (quantum optics)

  18. Eficiência agronômica de fertilizantes fosfatados fluidos e sólidos

    Directory of Open Access Journals (Sweden)

    W.B. Scivittaro

    1997-09-01

    Full Text Available Um experimento para avaliar a eficiência agronômica de fertilizantes fosfatados fluidos e sólidos foi desenvolvido em casa de vegetação no Centro de Energia Nuclear na Agricultura - CENA/USP, em Piracicaba (SP, de junho a outubro de 1992. Plantas de milho foram cultivadas durante 30 dias, por três cultivos sucessivos, em vasos contendo 1 kg de dois latossolos vermelho-amarelos com diferentes capacidades de retenção de fósforo. Os fosfatos na forma fluida - ácido fosfórico e suspensão coloidal 10-30-00 e sólida - fosfato monoamônico e superfosfato triplo foram aplicados no primeiro cultivo nas doses 0, 70, 140 e 210 mg kg-1 de P2O5 (0, 30,6, 61,2 e 91,8 mg kg-1 de P. Avaliaram-se os tratamentos pelo rendimento de matéria seca, pela absorção de fósforo e pelos índices: de eficiência agronômica (IEA e equivalente em superfosfato triplo (EqST. Os resultados indicaram não haver diferenças entre as fontes fosfatadas fluidas e sólidas quanto ao seu efeito sobre a produção de matéria seca e absorção de fósforo pelas plantas de milho. Entretanto, a aplicação de doses crescentes dos fosfatos aos solos promoveu aumentos significativos no rendimento de matéria seca e absorção de fósforo. Em ambos os solos, a eficiência agronômica dos fertilizantes fosfatados fluidos e sólidos foi semelhante.

  19. A Governança Corporativa Influencia a Eficiência das Empresas Brasileiras?

    Directory of Open Access Journals (Sweden)

    Igor Bernardi Sonza

    2014-05-01

    Full Text Available O conflito de interesses entre executivos e proprietários é uma questão amplamente difundida na academia, já documentada em 1932 por Berle e Means, trazendo à tona o clássico conflito de interesses entre agente e principal discutido pela Teoria da Agência. A premissa por trás da governança corporativa é que as pessoas que estão dentro das corporações não necessariamente agem visando o melhor para os provedores de fundos. Partindo deste pressuposto, o trabalho em questão visa verificar a influência dos aspectos de governança corporativa na eficiência das empresas de capital aberto brasileiras. O estudo une técnicas de otimização estática através de Análise Envoltória de Dados (DEA para identificar a eficiência das empresas de capital aberto, com Dados em Painel para identificar a influência da governança corporativa na eficiência das empresas. Os dados foram coletados manualmente dos relatórios 20-F da Security Exchange Commission (SEC das empresas brasileiras que possuem American Depositary Receipts (ADRs, já que a base de dados não está disponível, no Brasil, de uma forma completa. Grande parte das hipóteses foi confirmada, evidenciando as condições particulares das finanças corporativas no Brasil no que tange a Governança Corporativa. A incipiência do mercado de capitais brasileiro é percebida em várias análises, ressaltando que o histórico do sistema corporativo brasileiro é um dos limitantes da eficiência das empresas. As condições que prevalecem são: (i alta sobreposição propriedade-direção; (ii conselhos de administração de baixa efetividade; (iii em grupos familiares, os papéis dos acionistas, dos conselhos e da direção não são bem definidos; (iv existe pouca clareza quanto à relação benefício-custo da boa governança; (v baixa eficácia dos conselhos de administração; e (vi indícios de conflitos de interesses, relativizados por incentivos explícitos e implícitos.

  20. Eficiência agronômica de rejeitos da indústria de fertilizantes fosfatados

    OpenAIRE

    Garcia, Luciana de Arruda [UNESP

    2014-01-01

    A produção de fertilizantes fosfatados solúveis gera muitos rejeitos, cujo aproveitamento não é possível pelos atuais métodos industriais, acarretando perdas elevadas de P no beneficiamento, através da subutilização dos depósitos de fosfato, representando, portanto, um bem mineral não utilizado e um problema ambiental preocupante, devido aos grandes volumes envolvidos. Neste contexto, o objetivo deste trabalho foi avaliar a eficiência agronômica de dois rejeitos da indústria de fertilizantes ...

  1. Melhoria da eficiência energética em sistemas motrizes industriais

    Directory of Open Access Journals (Sweden)

    Antonio Vanderley Herrero Sola

    2015-09-01

    Full Text Available A comunidade científica internacional tem considerado o uso eficiente de energia em sistemas de produção extremamente importante para o desenvolvimento sustentável. Este artigo estuda a melhoria da eficiência energética em sistemas motrizes industriais por meio de mudança tecnológica. Inicialmente é feita uma revisão de literatura para apresentar as principais ações e barreiras para a melhoria da eficiência energética em sistemas industriais de energia e também destacar o uso de uma abordagem multicritério em caso de mudança tecnológica. O artigo apresenta um estudo de caso em uma indústria com o objetivo de ordenar motores elétricos para serem substituídos utilizando o método multicritério PROMETHEE II. O estudo revela que a escolha dos critérios pode alterar a ordem de prioridade de escolha das tecnologias a serem substituídas, com impacto no desempenho das novas tecnologias. O artigo enfatiza a importância da integração de todas as áreas da empresa para que sejam atendidos os interesses da organização.

  2. Um modelo para a avaliação da eficiência hídrica de produtos

    OpenAIRE

    Rodrigues, Carla Andreia Pimentel

    2008-01-01

    No presente trabalho é proposto um modelo de Certificação e Rotulagem da Eficiência Hídrica de Produtos. É ainda feita uma descrição de outros sistemas análogos, actualmente implementados em diversos países, comparando os respectivos modelos, e é analisado o caso particular do sistema de rotulagem que se pretende implementar em Portugal, para certificação de eficiência hídrica de produtos. Finalmente, apresenta-se um caso de estudo para avaliação da poupança de água co...

  3. Ganhos de eficiência fertilizante em bananeira sob irrigação e fertirrigação

    Directory of Open Access Journals (Sweden)

    Luiz Antonio Junqueira Teixeira

    2011-03-01

    Full Text Available O aumento da eficiência fertilizante tem sido cada vez mais almejado nas boas práticas de manejo da adubação de culturas, não somente buscando reduzir custos de produção, mas também reduzir possíveis impactos ambientais. Com o objetivo de avaliar a eficiência dos fertilizantes nitrogenados e potássicos no cultivo da bananeira, foram realizados dois experimentos de campo com a cultivar 'Nanicão' (Musa AAA, subgrupo Cavendish, no Planalto do Estado de São Paulo, durante quatro ciclos de produção. Esta região caracteriza-se por estação chuvosa no verão e seca no inverno. No primeiro experimento, avaliou-se a eficiência da aplicação das doses de N: 0; 200; 400 e 800 kg ha-1 e de K: 0; 300; 600 e 900 kg ha-1 de K2O, em sistema de cultivo irrigado, comparado ao de sequeiro. No segundo experimento, estudou-se a eficiência da adubação com N e K aplicada por fertirrigação e de modo convencional via solo. Nos dois experimentos, a irrigação e a fertirrigação foram feitas por microaspersão, empregando-se como fontes de N e de K nitrato de amônio e cloreto de potássio, respectivamente. A eficiência dos fertilizantes foi estimada pela relação entre a massa dos frutos produzidos por unidade de nutriente aplicado. Para a média das doses empregadas e dos ciclos de produção, observou-se que a irrigação incrementou a eficiência da adubação em relação ao sequeiro, em aproximadamente 36 % e 32 %, respectivamente, para nitrogênio e potássio. A aplicação de nitrogênio e potássio via fertirrigação promoveu aumento de 36 % na eficiência fertilizante em relação à adubação sólida convencional, via solo. Incrementos na eficiência dos fertilizantes decorrentes da irrigação e da fertirrigação possibilitaram diminuir os gastos com o uso destes insumos.

  4. Increased frequency of CD4{sup -}8{sup -}T cells bearing T-cell receptor {alpha}{beta} chains in peripheral blood of atomic bomb survivors exposed to high doses

    Energy Technology Data Exchange (ETDEWEB)

    Yoichiro Kusunoki; Seishi Kyoizumi; Yuko Hirai; Shoichiro Fujita; Mitoshi Akiyama [Radiation Effects Research Foundation, Hiroshima (Japan)

    1994-07-01

    A rare T-cell subpopulation, CD4{sup -z}8{sup -}{alpha}{beta} cells, may be differentiated through a pathway (or pathways) different from the pathway(s) of conventional CD4+ or CD8+ cells. In the present study, the frequencies of CD4{sup -}8{sup -} T cells in peripheral-blood {alpha}{beta} T cells in 409 atomic bomb survivors were determined to investigate late effects of radiation on the composition of human T-cell subpopulations. The frequency of CD4{sup -}8{sup -}{alpha}{beta} T-cell decreased significantly with the subject`s age and was higher in females than males. A significant increase in the frequency was found in the survivors exposed to more than 1.5Gy, suggesting that the previous radiation exposure altered differentiation and development of T cells. 25 refs., 4 figs., 3 tabs.

  5. Increased frequency of CD4-8-T cells bearing T-cell receptor αβ chains in peripheral blood of atomic bomb survivors exposed to high doses

    International Nuclear Information System (INIS)

    Yoichiro Kusunoki; Seishi Kyoizumi; Yuko Hirai; Shoichiro Fujita; Mitoshi Akiyama

    1994-01-01

    A rare T-cell subpopulation, CD4 -z 8 - αβ cells, may be differentiated through a pathway (or pathways) different from the pathway(s) of conventional CD4+ or CD8+ cells. In the present study, the frequencies of CD4 - 8 - T cells in peripheral-blood αβ T cells in 409 atomic bomb survivors were determined to investigate late effects of radiation on the composition of human T-cell subpopulations. The frequency of CD4 - 8 - αβ T-cell decreased significantly with the subject's age and was higher in females than males. A significant increase in the frequency was found in the survivors exposed to more than 1.5Gy, suggesting that the previous radiation exposure altered differentiation and development of T cells. 25 refs., 4 figs., 3 tabs

  6. Atomic clocks for geodesy

    Science.gov (United States)

    Mehlstäubler, Tanja E.; Grosche, Gesine; Lisdat, Christian; Schmidt, Piet O.; Denker, Heiner

    2018-06-01

    We review experimental progress on optical atomic clocks and frequency transfer, and consider the prospects of using these technologies for geodetic measurements. Today, optical atomic frequency standards have reached relative frequency inaccuracies below 10‑17, opening new fields of fundamental and applied research. The dependence of atomic frequencies on the gravitational potential makes atomic clocks ideal candidates for the search for deviations in the predictions of Einstein’s general relativity, tests of modern unifying theories and the development of new gravity field sensors. In this review, we introduce the concepts of optical atomic clocks and present the status of international clock development and comparison. Besides further improvement in stability and accuracy of today’s best clocks, a large effort is put into increasing the reliability and technological readiness for applications outside of specialized laboratories with compact, portable devices. With relative frequency uncertainties of 10‑18, comparisons of optical frequency standards are foreseen to contribute together with satellite and terrestrial data to the precise determination of fundamental height reference systems in geodesy with a resolution at the cm-level. The long-term stability of atomic standards will deliver excellent long-term height references for geodetic measurements and for the modelling and understanding of our Earth.

  7. Solution of the comoving-frame equation of transfer in spherically symmetric flows. IV. Frequency-dependent source functions for scattering by atoms and electrons

    International Nuclear Information System (INIS)

    Mihalas, D.; Kunasz, P.B.; Hummer, D.G.

    1976-01-01

    A numerical method is presented of solving the radiative transfer equation in the comoving frame of a spherically symmetric expanding atmosphere in which both the line and the electron-scattering source function can depend on frequency (i.e., when there is partial frequency redistribution in the scattering process). This method is used to assess the adequacy of various assumptions regarding frequency redistribution in the comoving frame and to discuss the effects of electron scattering more accurately than previously possible. The methods developed here can be used in realistic model atmospheres to account for the (major) effects of electron scattering upon emergent flux profiles

  8. Eficiência de isolamento e de plaqueamento de protoplastos de laranja-doce

    Directory of Open Access Journals (Sweden)

    Lívia Mendes de Castro

    2011-06-01

    Full Text Available O isolamento e plaqueamento de protoplastos são fatores fundamentais para o sucesso no cultivo in vitro deste tipo de explante visando a manipulações genéticas. A composição da solução enzimática no isolamento, a densidade de cultivo, bem como o próprio genótipo utilizado são variáveis importantes nestas etapas. Desta forma, o objetivo do trabalho foi avaliar a eficiência de isolamento de protoplastos em função de três soluções enzimáticas e a eficiência de plaqueamento em função de cinco densidades de protoplastos e diferentes composições de meio de cultura em cultivares de laranja-doce. As soluções enzimáticas avaliadas para o isolamento de protoplastos foram: 1. celulase Onozuka RS 1%, macerase R-10 1% e pectoliase 0,2%; 2. celulase Onozuka RS 1%, macerase R-10 1% ; 3. celulase Onozuka R-10 4%, macerase R-10 1%. O plaqueamento dos protoplastos foi realizado nas densidades de 2 x 10(4; 5 x 10(4; 10(5; 2x 10(5 e 3 x 10(5 protoplastos.mL-1, nos meios de cultura EME 0,7M, BH3 0,7M e BH3 + EME 0,7M em ausência de luz, a 25 ± 1 ºC. A solução enzimática 2 proporcionou maior rendimento no isolamento de protoplastos das cultivares 'Hamlin', 'Natal' e 'Pera', e a solução enzimática 1 foi a mais adequada para a laranja 'Westin'. Para a cultivar 'Lima-Verde', a solução enzimática 3 foi a mais eficiente. A eficiência final de plaqueamento, avaliada aos 90 dias de cultivo, foi superior nas densidades de 3 x 10(5 e 2 x 10(5 protoplastos.mL-1 para as cultivares 'Hamlin', 'Natal' e 'Lima-Verde', e nas densidades de 2 x 10(5 e 10(5 protoplastos.mL-1 para a laranja 'Westin'.

  9. Characterization of the molecular structure and mechanical properties of polymer surfaces and protein/polymer interfaces by sum frequency generation vibrational spectroscopy and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Koffas, Telly Stelianos [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    Sum frequency generation (SFG) vibrational spectroscopy, atomic force microscopy (AFM), and other complementary surface-sensitive techniques have been used to study the surface molecular structure and surface mechanical behavior of biologically-relevant polymer systems. SFG and AFM have emerged as powerful analytical tools to deduce structure/property relationships, in situ, for polymers at air, liquid and solid interfaces. The experiments described in this dissertation have been performed to understand how polymer surface properties are linked to polymer bulk composition, substrate hydrophobicity, changes in the ambient environment (e.g., humidity and temperature), or the adsorption of macromolecules. The correlation of spectroscopic and mechanical data by SFG and AFM can become a powerful methodology to study and engineer materials with tailored surface properties. The overarching theme of this research is the interrogation of systems of increasing structural complexity, which allows us to extend conclusions made on simpler model systems. We begin by systematically describing the surface molecular composition and mechanical properties of polymers, copolymers, and blends having simple linear architectures. Subsequent chapters focus on networked hydrogel materials used as soft contact lenses and the adsorption of protein and surfactant at the polymer/liquid interface. The power of SFG is immediately demonstrated in experiments which identify the chemical parameters that influence the molecular composition and ordering of a polymer chain's side groups at the polymer/air and polymer/liquid interfaces. In general, side groups with increasingly greater hydrophobic character will be more surface active in air. Larger side groups impose steric restrictions, thus they will tend to be more randomly ordered than smaller hydrophobic groups. If exposed to a hydrophilic environment, such as water, the polymer chain will attempt to orient more of its hydrophilic groups to

  10. Produtividade e eficiência no setor agropecuário do nordeste brasileiro

    OpenAIRE

    Araujo,Jair Andrade; Mancal,Ansu

    2015-01-01

    Resumo:Esse artigo analisa a produtividade total dos fatores na região Nordeste do Brasil, a região brasileira que possui limitações em termos de recursos naturais para produção agrícola. Estima-se a fronteira de produção e determina-se o índice de produtividade total dos fatores (PTF) de Malmquist, o qual é decomposto nos índices de variação de eficiência e variação tecnológica. As conclusões indicam que o crescimento da PTF não foi homogêneo entre os estados nordestinos e que o setor agrope...

  11. Eficiência térmica de materiais de cobertura

    OpenAIRE

    Muniz-Gäal, Lígia Parreira; Pezzuto, Cláudia Cotrim; Carvalho, Marcius Fabius Henriques de; Mota, Lia Toledo Moreira

    2018-01-01

    Resumo Acorreta especificação dos materiais de cobertura pode contribuir tanto para a melhoria da eficiência energética em edificações como para a mitigação do efeito de ilha de calor urbana. No entanto, a carência de caracterização das propriedades térmicas desses materiais ainda é constante. Esta pesquisa investiga a refletância solar em três diferentes tipos de materiais de cobertura: telha cerâmica esmaltada, cerâmica rústica e de concreto com amostras de diferentes cores. A refletância s...

  12. Frequency shift due to blackbody radiation in a cesium atomic fountain and improvement of the clock performances; Deplacement de frequence du au rayonnement du corps noir dans une fontaine atomique a cesium et amelioration des performances de l'horloge

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S

    2004-07-01

    FO1 was the first caesium fountain primary frequency standard in the world. The most recent evaluation in 2002 before improvement reached an accuracy of 1*10{sup -15} when operated with optical molasses. Working as an extremely precise and stable instrument, FO1 has contributed to fundamental physics and technical measurements: - Frequency comparison between Cs and Rb fountains over an interval of 5 years sets an upper limit for a possible variation of the fine structure constant as |alpha/alpha| < 2*10{sup -15}/y. The resolution is about 5 times better than the previous test in our laboratory. The projected accuracy of the space clock PHARAO is 1*10{sup -16}. We confirmed its Ramsey cavity performance by testing the phase difference between the two interaction zones in FO1. The measured temperature T dependent frequency shift of the Cs clock induced by the blackbody radiation field is given as nu(T)=154(6)*10{sup -6}*(T/300){sup 4}[1+{epsilon}(T/300){sup 2}] Hz with the theoretical value {epsilon} = 0,014. The obtained accuracy represents a 3 times improvement over the previous measurement by the PTB group. Some improvements have been carried out on FO1. The new FO1 version works directly with optical molasses loaded by a laser slowed atomic beam. The application of the adiabatic passage method to perform the state selection allows us to determine the atom number dependent frequency shifts due to the cold collision and cavity pulling effects at a level of of 10{sup -16}. Recently, the obtained frequency stability is 2,8*10{sup -14}*{tau}{sup -1/2} for about 4*10{sup 6} detected atoms. The accuracy is currently under evaluation, the expected value is a few times 10{sup -16}. (author)

  13. A eficiência de formação estelar em Musca

    Science.gov (United States)

    Hickel, G. R.; Vilas-Boas, J. W. S.; Roberto, A. J.., Jr.; Khan, R. P.

    2003-08-01

    Apresentamos os resultados de um survey no infravermelho próximo (bandas J e H), executado no Laboratório Nacional de Astrofísica, na direção da nuvem escura em forma de filamento de Musca (observamos ao longo de todo o filamento, além de todas as fontes pontuais IRAS e/ou fontes ROSAT brilhantes a uma distância de 2o da nuvem). Nosso objetivo é determinar a eficiência de formação estelar para esta nuvem escura (massa de estrelas formadas/massa da nuvem), procurando por objetos estelares jovens de pequena massa no seu interior e/ou evoluídos o suficiente para estarem afastados do local de nascimento, mas ainda mostrando características de objetos pré-seqüência principal como emissão de raios-X e excesso de emissão no infravermelho próximo. Este survey não estabeleceu nenhum viés na seleção de fontes pontuais IRAS ou fontes ROSAT, uma vez que a imensa maioria das fontes pontuais IRAS nesta região têm qualidade de fluxo ruim. Os candidatos a objetos estelares jovens foram selecionados pelo excesso no índice de cor (J-H), descontados os efeitos da extinção interestelar na linha de visada, determinada através da emissão estendida no infravermelho distante (IRAS). Estimativas de massa foram feitas para estes candidatos, através da relação massa-luminosidade, para calcular a eficiência de formação estelar de Musca.

  14. 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...

  15. Atomic beams probe surface vibrations

    International Nuclear Information System (INIS)

    Robinson, A.L.

    1982-01-01

    In the last two years, surface scientist have begun trying to obtain the vibrational frequencies of surface atoms in both insulating and metallic crystals from beams of helium atoms. It is the inelastic scattering that researchers use to probe surface vibrations. Inelastic atomic beam scattering has only been used to obtain vibrational frequency spectra from clean surfaces. Several experiments using helium beams are cited. (SC)

  16. Atom optics

    International Nuclear Information System (INIS)

    Balykin, V. I.; Jhe, W.

    1999-01-01

    Atom optics, in analogy to neutron and electron optics, deals with the realization of as a traditional elements, such as lenes, mirrors, beam splitters and atom interferometers, as well as a new 'dissipative' elements such as a slower and a cooler, which have no analogy in an another types of optics. Atom optics made the development of atom interferometer with high sensitivity for measurement of acceleration and rotational possible. The practical interest in atom optics lies in the opportunities to create atom microprobe with atom-size resolution and minimum damage of investigated objects. (Cho, G. S.)

  17. Atom-by-atom assembly

    International Nuclear Information System (INIS)

    Hla, Saw Wai

    2014-01-01

    Atomic manipulation using a scanning tunneling microscope (STM) tip enables the construction of quantum structures on an atom-by-atom basis, as well as the investigation of the electronic and dynamical properties of individual atoms on a one-atom-at-a-time basis. An STM is not only an instrument that is used to ‘see’ individual atoms by means of imaging, but is also a tool that is used to ‘touch’ and ‘take’ the atoms, or to ‘hear’ their movements. Therefore, the STM can be considered as the ‘eyes’, ‘hands’ and ‘ears’ of the scientists, connecting our macroscopic world to the exciting atomic world. In this article, various STM atom manipulation schemes and their example applications are described. The future directions of atomic level assembly on surfaces using scanning probe tips are also discussed. (review article)

  18. Análise da eficiência dos sistemas estruturais para edifícios em concreto

    Directory of Open Access Journals (Sweden)

    Gildemir Silva

    Full Text Available Resumo Nos últimos anos houve uma evolução dos métodos construtivos empregados no Brasil, principalmente no que se refere às estruturas de concreto. Embora a literatura sobre eficiência na construção civil seja vasta, a proposição de métodos não paramétricos para a análise de eficiência de processos construtivos ainda é bastante limitada. Este trabalho apresenta um modelo para análise de eficiência baseado na técnica Data Envelopment Analysis (DEA para uma análise comparada da eficiência dos sistemas estruturais de edifícios em concreto, avaliando a utilização eficiente dos insumos de produção (capital e trabalho para a produção da estrutura. No trabalho foram comparados diversos sistemas estruturais, entre os quais pavimentos formados por lajes nervuradas apoiadas em faixas protendidas, formados por lajes apoiadas em vigas altas e formados por lajes apoiadas diretamente nos pilares, em um total de 23 obras, de 16 construtoras com reconhecida atuação no mercado imobiliário, monitoradas periodicamente, o que permite um diagnóstico do setor. O modelo proposto pode ser usado pelos planejadores com vantagens significativas. Os resultados apontam que pode haver ganhos financeiros substanciais ao melhor alocar mão de obra para o mesmo método construtivo.

  19. Avaliação de projetos de eficiência energética no segmento baixa renda

    OpenAIRE

    Oliveira, Felipe Conti de Souza

    2012-01-01

    O presente trabalho visa avaliar o resultado dos projetos de eficiência energética para o segmento baixa renda, comparando resultados de projetos de troca de equipamentos obsoletos por equipamentos novos e eficientes, com projeto de cunho educativo para o consumo eficiente de energia. Faz também parte do trabalho verificar os resultados das ações dos dois projetos combinados.

  20. Interaction of an atom with the radiation field in the presence of collisions. Application to the problem of frequency redistribution of light

    International Nuclear Information System (INIS)

    Yelnik, J.-B.

    1978-06-01

    The purpose of this work mainly consisted in (a) taking into account all the orders of the atom-radiation interaction (in a low intensity field) for strictly processing the natural enlargement over the entire spectral domain of the line and (b) simultaneously applying the unified theories of the collision enlargement to the radiation distribution problem. These redistribution formulae also drawn up by Nienhuis et al. were supposed to apply also outside the impact domain. However, it was soon realised that these results were not satisfactory since, in certain cases (observation in the wings and excitation in the centre or vice-versa), they could give rise to a negative fluorescence profile. This drawback was due to the approximation consisting in disregarding the effect of the radiative processes throughout the duration of a collision. An accurate treatment of the redistribution that no longer makes use of the incriminated approximation is presented in the appendix. In this way, new results are obtained which no longer exhibit the irregularities of those obtained in the preceding treatment and which apply from the centre of the line to the near-by quasi-static domain [fr

  1. Squeezing effects of an atom laser: Beyond the linear model

    International Nuclear Information System (INIS)

    Jing Hui; Ge Molin; Chen Jingling

    2002-01-01

    We investigate the quantum dynamics and statistics of an atom laser by taking into account binary atom-atom collisions. The rotating wave approximation Hamiltonian of the system is solved analytically . We show that the nonlinear atom-atom interactions could yield periodic quadrature squeezing effects in the atom laser output beam, although the input radio frequency field is in a Glauber coherent state

  2. Single-atom lasing induced atomic self-trapping

    International Nuclear Information System (INIS)

    Salzburger, T.; Ritsch, H.

    2004-01-01

    We study atomic center of mass motion and field dynamics of a single-atom laser consisting of a single incoherently pumped free atom moving in an optical high-Q resonator. For sufficient pumping, the system starts lasing whenever the atom is close to a field antinode. If the field mode eigenfrequency is larger than the atomic transition frequency, the generated laser light attracts the atom to the field antinode and cools its motion. Using quantum Monte Carlo wave function simulations, we investigate this coupled atom-field dynamics including photon recoil and cavity decay. In the regime of strong coupling, the generated field shows strong nonclassical features like photon antibunching, and the atom is spatially confined and cooled to sub-Doppler temperatures. (author)

  3. Frações de fósforo em estrumes e sua eficiência como adubo fosfatado

    Directory of Open Access Journals (Sweden)

    P. C. Cassol

    2001-09-01

    Full Text Available Os estrumes empregados como fontes de fósforo podem ter eficiência fertilizante diferente da dos adubos comerciais solúveis. Tal eficiência pode variar com a origem do estrume e com as proporções das diferentes frações químicas do P total contido. A eficiência de estrumes de frangos de corte e de bovinos de leite, relativamente ao superfosfato triplo-ST, e a correlação desta eficiência com frações de fósforo contidas nestes materiais foram estimadas em experimento de casa de vegetação. Os tratamentos aplicados foram: um controle, sem P; as doses 6,6, 13,2 e 19,7 mg kg-1 de P de ST, e uma dose única de 15,3 mg kg-1 de P de 11 amostras de cada um dos dois tipos de estrumes. Utilizou-se um Podzólico Vermelho-Escuro e a resposta aos tratamentos foi determinada com o cultivo de milheto (Pennisetum americanum durante 27 dias, a partir da adubação fosfatada, período em que foram colhidos três cortes de plantas. As frações de fósforo dos estrumes foram determinadas por extrações seqüenciais. O índice de eficiência (IE, estimado pelo método de equivalentes em ST, dos estrumes de frango foi de 0,84 ± 0,071, valor menor do que o dos estrumes de bovinos de leite, de 0,94 ± 0,095. Não ocorreu diferença de IE entre as amostras de estrumes de mesma espécie animal. Considerando todas as amostras, o IE apresentou correlação positiva com as proporções de P lábil, extraídas por resina trocadora de ânions e NaHCO3 0,5 mol L-1, e de P inorgânico total e correlação negativa com as proporções de P extraídas por NaOH 0,1 mol L-1 e HCl 0,5 mol L-1 e de P orgânico total. Não ocorreu correlação entre o IE e o teor total de P dos estrumes.

  4. Eficiência dos aeroportos internacionais brasileiros: uma análise envoltória de dados com bootstrap

    Directory of Open Access Journals (Sweden)

    Ana Elisa Périco

    Full Text Available Resumo A eficiência adquiriu maior relevância entre as organizações no cenário de mercados abertos, que teve início no Brasil por volta dos anos 1990. O objetivo deste artigo foi analisar, por envoltória de dados com bootstrap, a eficiência dos aeroportos brasileiros, utilizando as bases de dados da Agência Nacional de Aviação Civil (ANAC e da Empresa Brasileira de Infraestrutura Aeroportuária (INFRAERO de 2010, 2011 e 2012. Uma regressão múltipla foi utilizada para validar as variáveis do modelo proposto. Nesse modelo, a medida utilizada para representar o desempenho dos aeroportos foi a quantidade de passageiros processados (variável dependente; para as variáveis que determinam o desempenho (variáveis independentes foram utilizados: número de pistas, número de balcões de check-in, número de estacionamento de aeronaves e área de passageiros. A partir de então, a técnica Análise Envoltória de Dados foi aplicada para os 16 aeroportos internacionais brasileiros, em abordagem operacional. Para corrigir os valores de eficiência encontrados, tendo em vista o erro aleatório inerente aos dados, aplicou-se uma abordagem da técnica de bootstrap. Os resultados encontrados apontam que a grandeza de um aeroporto não foi determinante para atribuir eficiência, embora seja critério relevante para impulsionar melhorias no seu desempenho. Convém salientar, também, que a utilização dos recursos (inputs para o alcance do produto (output foi o critério mais relevante na busca do bom desempenho e da eficiência aeroportuária no estudo aqui apresentado. Nesse sentido, o aeroporto de Curitiba, na Região Sul do país, foi classificado como o mais eficiente em todos os períodos, e os aeroportos do Galeão (Rio de Janeiro e Manaus (Amazonas como os menos eficientes.

  5. Stopping atoms with diode lasers

    International Nuclear Information System (INIS)

    Watts, R.N.; Wieman, C.E.

    1986-01-01

    The use of light pressure to cool and stop neutral atoms has been an area of considerable interest recently. Cooled neutral atoms are needed for a variety of interesting experiments involving neutral atom traps and ultrahigh-resolution spectroscopy. Laser cooling of sodium has previously been demonstrated using elegant but quite elaborate apparatus. These techniques employed stabilized dye lasers and a variety of additional sophisticated hardware. The authors have demonstrated that a frequency chirp technique can be implemented using inexpensive diode lasers and simple electronics. In this technique the atoms in an atomic beam scatter resonant photons from a counterpropagating laser beam. The momentum transfer from the photons slows the atoms. The primary difficulty is that as the atoms slow their Doppler shift changes, and so they are no longer in resonance with the incident photons. In the frequency chirp technique this is solved by rapidly changing the laser frequency so that the atoms remain in resonance. To achieve the necessary frequency sweep with a dye laser one must use an extremely sophisticated high-speed electrooptic modulator. With a diode laser, however, the frequency can be smoothly and rapidly varied over many gigahertz simply by changing the injection current

  6. Atomic polarizabilities

    International Nuclear Information System (INIS)

    Safronova, M. S.; Mitroy, J.; Clark, Charles W.; Kozlov, M. G.

    2015-01-01

    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

  7. Atomic polarizabilities

    Energy Technology Data Exchange (ETDEWEB)

    Safronova, M. S. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Clark, Charles W. [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899-8410 (United States); Kozlov, M. G. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation)

    2015-01-22

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.

  8. 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

  9. Atomic physics

    International Nuclear Information System (INIS)

    Armbruster, P.; Beyer, H.; Bosch, F.; Dohmann, H.D.; Kozhuharov, C.; Liesen, D.; Mann, R.; Mokler, P.H.

    1984-01-01

    The heavy ion accelerator UNILAC is well suited to experiments in the field of atomic physics because, with the aid of high-energy heavy ions atoms can be produced in exotic states - that is, heavy atoms with only a few electrons. Also, in close collisions of heavy ions (atomic number Z 1 ) and heavy target atoms (Z 2 ) short-lived quasi-atomic 'superheavy' systems will be formed - huge 'atoms', where the inner electrons are bound in the field of the combined charge Z 1 + Z 2 , which exceeds by far the charge of the known elements (Z <= 109). Those exotic or transient superheavy atoms delivered from the heavy ion accelerator make it possible to study for the first time in a terrestrial laboratory exotic, but fundamental, processes, which occur only inside stars. Some of the basic research carried out with the UNILAC is discussed. This includes investigation of highly charged heavy atoms with the beam-foil method, the spectroscopy of highly charged slow-recoil ions, atomic collision studies with highly ionised, decelerated ions and investigations of super-heavy quasi-atoms. (U.K.)

  10. Evolution Properties of Atomic Fidelity in the Combined Multi-Atom-Cavity Field System

    International Nuclear Information System (INIS)

    Wang Ju-Xia; Zhang Xiao-Juan; Zhang Xiu-Xing

    2015-01-01

    The atom fidelity is investigated in a system consisting of Mtwo-level atoms and M single-mode fields by use of complete quantum theory and numerical evaluation method. The influences of various system parameters on the evolution of atomic fidelity are studied. The results show that the atomic fidelity evolves in a Rabi oscillation manner. The oscillation frequency is mainly modulated by the coupling strength between atoms and light field, the atomic transition probabilities and the average photon numbers. Other factors hardly impact on the atomic fidelity. The present results may provide a useful approach to the maintenance of the atomic fidelity in the atom cavity field systems. (paper)

  11. 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...

  12. Eficiência de fungicidas no controle da brusone em trigo

    Directory of Open Access Journals (Sweden)

    João Romero do Amaral Santos de Carvalho Rocha

    2014-12-01

    Full Text Available Causada pelo fungo Pyricularia grisea, a brusone do trigo constitui-se num dos principais entraves à expansão da produção tritícola no Brasil Central. O objetivo deste trabalho foi avaliar a eficiência de fungicidas no controle da brusone em trigo. Foram utilizados três fungicidas, com princípios ativos distintos, combinados com quatro genótipos de trigo. Realizaram-se duas aplicações do produto comercial, sendo estas no estádio 45 e 65 da escala de Zadokset al. A inoculação artificial com os esporos de P. grisea ocorreu no estádio 58-60 da referida escala. Determinou-se a área abaixo da curva de progresso da doença (AACPD, a severidade em folhas bandeira (SEVFB e em espigas (SEVEsp e quantificou-se a produção de grãos (PG.Ao final do trabalho, os diferentes parâmetros analisados foram submetidos à análise de correlação de Pearson.Os fungicidas epoxiconazol+piraclostrobina e tebuconazol+trifloxistrobina foram os que proporcionaram menor AACPD nos genótipos VI 03061, VI 07505 e BRS 254. Não houve diferença para SEVFB entre os genótipos na presença de fungicidas. As linhagens VI 98053 e VI 07505 apresentam menor SEVFB na ausência de fungicidas.O fungicida tebuconazole+trifloxistrobina proporcionou maior PG e menor SEVEsp. A severidade da doença em espigas foi maior do que em folhas bandeira. O controle da brusoneem trigo através da aplicação de fungicidas mostrou-se eficiente em folhas bandeira, mas não eficiente para o controle nas espigas.

  13. Neutralidade de Rede: Finalidade, Eficácia, Efetividade e Eficiência

    Directory of Open Access Journals (Sweden)

    Igor Drumond

    2015-05-01

    Full Text Available Propósito – Este artigo pretende abordar o papel da neutralidade de rede, partindo da premissa de uma estrutura de rede de internet escassa. Metodologia/abordagem/design – O artigo descreve algumas histórias de sucesso e fracasso de serviços de internet para ilustrar alguns pontos daquilo que se entende por neutralidade, como também traça um paralelo das dificuldades dos provedores de conteúdo não enfrentadas pelos provedores de rede e como as estratégias destes podem, ao mesmo tempo, violar a neutralidade, causar prejuízos aos usuários e aos provedores de conteúdo ou interferir negativamente nas estratégias destes. Também se promove a uma comparação do atual cenário regulatório no Brasil e nos Estados Unidos a respeito do tema e se utiliza da convergência e intersecção da Teoria dos Jogos, os custos de transação do Teorema de Coase, a Teoria do Interesse Público e a concepção de um sistema regulatório eficiente e equitativo para analisar os papéis dos atores em jogo. Resultados – Sugerem-se parâmetros de finalidade, eficácia, efetividade e eficiência como ferramentas para se evitarem violações à neutralidade no que diz respeito à oferta de serviços de internet pelas operadoras aos usuários-consumidores. Implicações práticas – O artigo auxilia na avaliação de situações cujas relações tenham potencial de violar o princípio da neutralidade de rede.

  14. Eficiência térmica de materiais de cobertura

    Directory of Open Access Journals (Sweden)

    Lígia Parreira Muniz-Gäal

    Full Text Available Resumo Acorreta especificação dos materiais de cobertura pode contribuir tanto para a melhoria da eficiência energética em edificações como para a mitigação do efeito de ilha de calor urbana. No entanto, a carência de caracterização das propriedades térmicas desses materiais ainda é constante. Esta pesquisa investiga a refletância solar em três diferentes tipos de materiais de cobertura: telha cerâmica esmaltada, cerâmica rústica e de concreto com amostras de diferentes cores. A refletância solar das amostras foi medida a partir do espectrômetro portátil ALTA II e posteriormente foi calculado o índice de refletância solar (SRI, baseado na norma ASTM E1980. Os resultados demonstraram que a variabilidade de cores impacta diretamente no desempenho com relação à refletância solar (cerâmica esmaltada de 0,11 - 0,67, concreto de 0,1 - 0,37, cerâmica rústica de 0,25 - 0,47. A telha de concreto apresentou menor SRI (39%. As cores claras mostraram ser mais eficientes apresentando maiores valores de refletância solar. Entretanto, a diversidade de tons claros acarretou variação na refletância solar (0,67, 0,37, 0,47, esmaltada, concreto e rústica, respectivamente. Os resultados relacionados neste estudo apontam a importância da análise da refletância solar dos materiais de cobertura e a necessidade de sua correta especificação em edificações.

  15. Time and frequency applications.

    Science.gov (United States)

    Hellwig, H

    1993-01-01

    An overview is given of the capabilities of atomic clocks and quartz crystal oscillators in terms of available precision of time and frequency signals. The generation, comparison, and dissemination of time and frequency is then discussed. The principal focus is to survey uses of time and frequency in navigation, communication, and science. The examples given include the Global Positioning System, a satellite-based global navigation system, and general and dedicated communication networks, as well as experiments in general relativity and radioastronomy. The number of atomic clocks and crystal oscillators that are in actual use worldwide is estimated.

  16. The Effect of Vibration Characteristics on the Atomization Rate in a Micro-Tapered Aperture Atomizer

    Directory of Open Access Journals (Sweden)

    Qiufeng Yan

    2018-03-01

    Full Text Available Because little is known about the atomization theory of a micro-tapered aperture atomizer, we investigated the vibration characteristics of this type of atomizer. The atomization mechanism of a micro-tapered aperture atomizer was described, and the atomization rate equation was deduced. As observed via microscopy, the angle of the micro-tapered aperture changes with the applied voltage, which proved the existence of a dynamic cone angle. The forward and reverse atomization rates were measured at various voltages, and the influence of the micro-tapered aperture and its variation on the atomization rate was characterized. The resonance frequency of the piezoelectric vibrator was obtained using a laser vibrometer, and the atomization rates were measured at each resonance frequency. From experiments, we found that the atomization rates at the first five resonance frequencies increased as the working frequency increased. At the fifth resonance frequency (121.1 kHz, the atomization rate was maximized (0.561 mL/min, and at the sixth resonance frequency (148.3 kHz, the atomization rate decreased significantly (0.198 mL/min. The experimental results show that the vibration characteristics of the piezoelectric vibrator have a relatively strong impact on the atomization rate. This research is expected to contribute to the manufacture of micro-tapered aperture atomizers.

  17. The Effect of Vibration Characteristics on the Atomization Rate in a Micro-Tapered Aperture Atomizer.

    Science.gov (United States)

    Yan, Qiufeng; Zhang, Jianhui; Huang, Jun; Wang, Ying

    2018-03-21

    Because little is known about the atomization theory of a micro-tapered aperture atomizer, we investigated the vibration characteristics of this type of atomizer. The atomization mechanism of a micro-tapered aperture atomizer was described, and the atomization rate equation was deduced. As observed via microscopy, the angle of the micro-tapered aperture changes with the applied voltage, which proved the existence of a dynamic cone angle. The forward and reverse atomization rates were measured at various voltages, and the influence of the micro-tapered aperture and its variation on the atomization rate was characterized. The resonance frequency of the piezoelectric vibrator was obtained using a laser vibrometer, and the atomization rates were measured at each resonance frequency. From experiments, we found that the atomization rates at the first five resonance frequencies increased as the working frequency increased. At the fifth resonance frequency (121.1 kHz), the atomization rate was maximized (0.561 mL/min), and at the sixth resonance frequency (148.3 kHz), the atomization rate decreased significantly (0.198 mL/min). The experimental results show that the vibration characteristics of the piezoelectric vibrator have a relatively strong impact on the atomization rate. This research is expected to contribute to the manufacture of micro-tapered aperture atomizers.

  18. Ubiquitous atom

    International Nuclear Information System (INIS)

    Spruch, G.M.; Spruch, L.

    1974-01-01

    The fundamentals of modern physics, including the basic physics and chemistry of the atom, elementary particles, cosmology, periodicity, and recent advances, are surveyed. The biology and chemistry of the life process is discussed to provide a background for considering the effects of atomic particles on living things. The uses of atomic power in space travel, merchant shipping, food preservation, desalination, and nuclear clocks are explored. (Pollut. Abstr.)

  19. Atomic physics

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    Research activities in atomic physics at Lawrence Berkeley Laboratory during 1976 are described. Topics covered include: experiments on stored ions; test for parity violation in neutral weak currents; energy conservation and astrophysics; atomic absorption spectroscopy, atomic and molecular detectors; theoretical studies of quantum electrodynamics and high-z ions; atomic beam magnetic resonance; radiative decay from the 2 3 Po, 2 levels of helium-like argon; quenching of the metastable 2S/sub 1/2/ state of hydrogen-like argon in an external electric field; and lifetime of the 2 3 Po level of helium-like krypton

  20. Experiments with cold hydrogen atoms

    International Nuclear Information System (INIS)

    Leonas, V.B.

    1981-01-01

    Numerous investigations of atomic processes in Waseous phase on the surface with participation of ''cold'' hydrogen atoms, made during the last years, are considered. The term ''cold atom'' means the range of relative collision energies E<10 MeV (respectively 'ultracold ' atoms at E< or approximately 1 MeV) which corresponds to the range of temperatures in tens (units) of K degrees. Three main ranges of investigations where extensive experimental programs are realized are considered: study of collisional processes with hydrogen atom participation, hydrogen atoms being of astrophysical interest; study of elastic atom-molecular scattering at superlow energies and studies on the problem of condensed hydrogen. Hydrogen atoms production is realized at dissociation in non-electrode high-frequency or superhigh-frequency discharge. A method of hydrogen quantum generator and of its modifications appeared to be rather an effective means to study collisional changes of spin state of hydrogen atoms. First important results on storage and stabilization of the gas of polarized hydrogen atoms are received

  1. ISO 50001 Norma mundial para a eficiência energética. Porquê uma norma mundial?

    OpenAIRE

    Branco, Paulo

    2013-01-01

    Nem sempre são fáceis os desafios ambientais associados ao consumo de energia. Sobretudo devido à forte dependência de combustíveis fósseis, torna-se cada vez mais evidente a inevitabilidade de agentes económicos, políticos, sociedade em geral, assumirem um compromisso focado na melhoria da eficiência energética e no uso racional da energia, decorrente das atividades económicas. Esta preocupação assume-se também como nacional. A norma NP EN ISO 50001 apresenta...

  2. Eficiência energética na administração do Porto de Sines

    OpenAIRE

    Guerreiro, Rita Fernandes

    2009-01-01

    Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia do Ambiente, perfil Gestão e Sistemas Ambientais A problemática energética é actualmente uma questão dominante nas agendas mundiais. A dependência de fontes de energia externas é uma realidade e compete aos governos e organizações mudar este paradigma, apostando na eficiência, segurança e fiabilidade do abastecimento. A actividade portuári...

  3. Detecting device of atomic probe

    International Nuclear Information System (INIS)

    Nikonenkov, N.V.

    1979-01-01

    Operation of an atomic-probe recording device is discussed in detail and its flowsheet is given. The basic elements of the atomic-probe recording device intented for microanalysis of metals and alloys in an atomic level are the storage oscillograph with a raster-sweep unit, a two-channel timer using frequency meters, a digital printer, and a control unit. The digital printer records information supplied by four digital devices (two frequency meters and two digital voltmeters) in a four-digit binary-decimal code. The described device provides simultaneous recording of two ions produced per one vaporation event

  4. Processo de trabalho e eficiência produtiva: Smith, Marx, Taylor e Lênin

    Directory of Open Access Journals (Sweden)

    Benedito Rodrigues de Moraes Neto

    2009-09-01

    Full Text Available A partir de reflexão sobre uma hipotética transição do capitalismo em sua natureza manufatureira ao socialismo, procura-se deixar marcada a razão pela qual, seguindo a proposta de Marx, essa transição exige que a produção se realize sob a égide da maquinaria. Consegue-se, como parte dessa reflexão, identificar, para o caso da manufatura, um trade-off entre eficiência produtiva e humanização das atividades de trabalho. Procura-se esclarecer que, dada a natureza do taylorismo-fordismo como "reinvenção da manufatura", o exercício de início especulativo passa a ter sentido histórico. Busca-se argumentar que a ampla assimilação do taylorismo-fordismo pela experiência de implantação do socialismo na União Soviética a aprisionou ao mencionado trade-off , fazendo com que a primeira experiência de superação do capitalismo se impregnasse perversamente da mediocridade imanente ao taylorismo-fordismo. Finalmente, são feitos rápidos comentários acerca dos desdobramentos da recente automação de base microeletrônica sobre a natureza de um projeto socialista.From an analysis of a hypothetical transition from manufacture capitalism to socialism, we intend to stress the reason why, according to Marx´s proposition, it is demanded that this transition takes place under machinery´s domain. In the case of manufacture it is possible to identify a trade-off between the productive efficiency and the humanization of the labor activities. We then intend to clarify that the initially hypothetical speculation acquires a historic sense in as much as taylorism-fordism´s nature can be understood as a "reinvention of the manufacturing system". We shall then argue that the wide assimilation of taylorism-fordism in the Soviet Union´s experience of socialism implementation imprisoned it within the mentioned trade-off, which caused the first experience of capitalism´s surmount to be perversely impregnated with the immanent mediocrity of

  5. 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.

  6. Early Atomism

    Indian Academy of Sciences (India)

    https://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, ...

  7. Atom spectroscopy

    International Nuclear Information System (INIS)

    Kodling, K.

    1981-01-01

    Experiments on atom photoabsorption spectroscopy using synchrotron radiation in the 10-1000 eV range are reviewed. Properties of the necessary synchrotron radiation and the experiment on absorption spectroscopy are briefly described. Comparison with other spectroscopy methods is conducted. Some data on measuring photoabsorption, photoelectron emission and atom mass spectra are presented [ru

  8. Exotic atoms

    International Nuclear Information System (INIS)

    Horvath, D.; Lambrecht, R.M.

    1984-01-01

    This bibliography on exotic atoms covers the years 1939 till 1982. The annual entries are headed by an introduction describing the state of affairs of the branch of science and listing the main applications in quantum electrodynamics, particle physics, nuclear physics, atomic physics, chemical physics and biological sciences. The bibliography includes an author index and a subject index. (Auth.)

  9. New sources of cold atoms for atomic clocks

    International Nuclear Information System (INIS)

    Aucouturier, E.

    1997-01-01

    The purpose of this doctoral work is the realisation of new sources of cold cesium atoms that could be useful for the conception of a compact and high-performance atomic clock. It is based on experiences of atomic physics using light induced atomic manipulation. We present here the experiences of radiative cooling of atoms that have been realised at the Laboratoire de l'Horloge Atomique from 1993 to 1996. Firstly, we applied the techniques of radiative cooling and trapping of atoms in order to create a three-dimensional magneto-optical trap. For this first experience, we developed high quality laser sources, that were used for other experiments. We imagined a new configuration of trapping (two-dimensional magneto-optical trap) that was the basis for a cold atom source. This design gives the atoms a possibility to escape towards one particular direction. Then, we have extracted the atoms from this anisotropic trap in order to create a continuous beam of cold atoms. We have applied three methods of extraction. Firstly, the launching of atoms was performed by reducing the intensity of one of the cooling laser beams in the desired launching direction. Secondly, a frequency detuning between the two laser laser beams produced the launching of atoms by a so-called 'moving molasses'. The third method consisted in applying a static magnetic field that induced the launching of atoms in the direction of this magnetic field. At the same time, another research on cold atoms was initiated at the I.H.A. It consisted in cooling a large volume of atoms from a cell, using an isotropic light. This offers an interesting alternative to the traditional optical molasses. (author)

  10. Frequency Standards and Metrology

    Science.gov (United States)

    Maleki, Lute

    2009-04-01

    Preface / Lute Maleki -- Symposium history / Jacques Vanier -- Symposium photos -- pt. I. Fundamental physics. Variation of fundamental constants from the big bang to atomic clocks: theory and observations (Invited) / V. V. Flambaum and J. C. Berengut. Alpha-dot or not: comparison of two single atom optical clocks (Invited) / T. Rosenband ... [et al.]. Variation of the fine-structure constant and laser cooling of atomic dysprosium (Invited) / N. A. Leefer ... [et al.]. Measurement of short range forces using cold atoms (Invited) / F. Pereira Dos Santos ... [et al.]. Atom interferometry experiments in fundamental physics (Invited) / S. W. Chiow ... [et al.]. Space science applications of frequency standards and metrology (Invited) / M. Tinto -- pt. II. Frequency & metrology. Quantum metrology with lattice-confined ultracold Sr atoms (Invited) / A. D. Ludlow ... [et al.]. LNE-SYRTE clock ensemble: new [symbol]Rb hyperfine frequency measurement - spectroscopy of [symbol]Hg optical clock transition (Invited) / M. Petersen ... [et al.]. Precise measurements of S-wave scattering phase shifts with a juggling atomic clock (Invited) / S. Gensemer ... [et al.]. Absolute frequency measurement of the [symbol] clock transition (Invited) / M. Chwalla ... [et al.]. The semiclassical stochastic-field/atom interaction problem (Invited) / J. Camparo. Phase and frequency noise metrology (Invited) / E. Rubiola ... [et al.]. Optical spectroscopy of atomic hydrogen for an improved determination of the Rydberg constant / J. L. Flowers ... [et al.] -- pt. III. Clock applications in space. Recent progress on the ACES mission (Invited) / L. Cacciapuoti and C. Salomon. The SAGAS mission (Invited) / P. Wolf. Small mercury microwave ion clock for navigation and radioScience (Invited) / J. D. Prestage ... [et al.]. Astro-comb: revolutionizing precision spectroscopy in astrophysics (Invited) / C. E. Kramer ... [et al.]. High frequency very long baseline interferometry: frequency standards and

  11. Atomic fusion, Gerrard atomic fusion

    International Nuclear Information System (INIS)

    Gerrard, T.H.

    1980-01-01

    In the approach to atomic fusion described here the heat produced in a fusion reaction, which is induced in a chamber by the interaction of laser beams and U.H.F. electromagnetic beams with atom streams, is transferred to a heat exchanger for electricity generation by a coolant flowing through a jacket surrounding the chamber. (U.K.)

  12. Superradiators created atom by atom

    Science.gov (United States)

    Meschede, Dieter

    2018-02-01

    High radiation rates are usually associated with macroscopic lasers. Laser radiation is “coherent”—its amplitude and phase are well-defined—but its generation requires energy inputs to overcome loss. Excited atoms spontaneously emit in a random and incoherent fashion, and for N such atoms, the emission rate simply increases as N. However, if these atoms are in close proximity and coherently coupled by a radiation field, this microscopic ensemble acts as a single emitter whose emission rate increases as N2 and becomes “superradiant,” to use Dicke's terminology (1). On page 662 of this issue, Kim et al. (2) show the buildup of coherent light fields through collective emission from atomic radiators injected one by one into a resonator field. There is only one atom ever in the cavity, but the emission is still collective and superradiant. These results suggest another route toward thresholdless lasing.

  13. Análise de eficiência na gestão do transporte urbano por ônibus em municípios brasileiros

    OpenAIRE

    Azambuja, Ana Maria Volkmer de

    2002-01-01

    Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Produção. Este estudo é um conjunto de procedimentos que tem como objetivo medir a eficiência na gestão do transporte público por ônibus, em municípios brasileiros, e subsidiar, assim, a Administração Pública na tomada de decisões. Para tanto, foram avaliados os principais métodos utilizados para medir eficiência, identificando aquele mais adequado para a solução do pro...

  14. Optical angular momentum and atoms.

    Science.gov (United States)

    Franke-Arnold, Sonja

    2017-02-28

    Any coherent interaction of light and atoms needs to conserve energy, linear momentum and angular momentum. What happens to an atom's angular momentum if it encounters light that carries orbital angular momentum (OAM)? This is a particularly intriguing question as the angular momentum of atoms is quantized, incorporating the intrinsic spin angular momentum of the individual electrons as well as the OAM associated with their spatial distribution. In addition, a mechanical angular momentum can arise from the rotation of the entire atom, which for very cold atoms is also quantized. Atoms therefore allow us to probe and access the quantum properties of light's OAM, aiding our fundamental understanding of light-matter interactions, and moreover, allowing us to construct OAM-based applications, including quantum memories, frequency converters for shaped light and OAM-based sensors.This article is part of the themed issue 'Optical orbital angular momentum'. © 2017 The Author(s).

  15. Two-dimensional atom localization via probe absorption in a four-level atomic system

    International Nuclear Information System (INIS)

    Wang Zhi-Ping; Ge Qiang; Ruan Yu-Hua; Yu Ben-Li

    2013-01-01

    We have investigated the two-dimensional (2D) atom localization via probe absorption in a coherently driven four-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of 2D atom localization can be significantly improved via adjusting the system parameters. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization

  16. Atomic interferometry

    International Nuclear Information System (INIS)

    Baudon, J.; Robert, J.

    2004-01-01

    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 λ = h/(mv), where λ 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.)

  17. Eficiência produtiva e reprodutiva em vacas leiteiras Productive and reproductive efficiency in dairy cows

    Directory of Open Access Journals (Sweden)

    Tisa Echevarria Leite

    2001-06-01

    Full Text Available O presente trabalho teve por objetivo avaliar efeitos de transtornos puerperais sobre a eficiência reprodutiva e produtiva de vacas da raça Holandês de uma estação experimental, durante 24 anos. Foram coletados dados produtivos e reprodutivos de 350 vacas. Todos os dados foram submetidos à análise descritiva. As variáveis dependentes: intervalo entre partos (IEP, intervalo parto concepção (IPC, intervalo parto primeiro cio (IPPC, número de crias (NC e produção de leite (PL foram submetidas a análise de variância para determinação dos efeitos da ocorrência de transtornos puerperais (aborto, natimorto, distocia e retenção de placenta e de mastite. A idade ao primeiro cio (IdPC foi de 29,4 meses, a idade ao primeiro parto (IdPP de 37,1 meses e a longevidade (L de 69,7 meses. O IEP apresentou média de 14,6 meses, o IPPC de 97,0 dias e o IPC de 150,7 dias. O intervalo entre cios (IEC apresentou média de 48,2 dias, sugerindo falhas na detecção de cios. Foi observado efeito significativo (PThe present study was conducted to evaluate the effects of post partum disorders on productive and reproductive performance of Holstein cows, from a dairy experimental station, during 24 years. Productive and reproductive data were collected from 350 cows. Analyses of variance was conducted to evaluate the effects of occurrence of post partum disorders (abortion, stillbirth, dystocia, retained placenta and mastitis on calving interval (IEP, calving to conception interval (IPC, calving to first estrus interval (IPPC, number of estrus before conception (NC and milk production (PL. The mean age at first estrus was 29.4 months and the mean age at first calving was 37.1 months. Mean IEP was 14.6 months, mean IPPC was 97.04 days and median IPC was 150.71 days. Median interestrus interval was 24 days, suggesting problems in a estrus detection. A significant effect of occurrence of abortion (P<0.05 was observed on IEP. Calving intervals were 258 days

  18. Navigation with Atom Interferometers

    Science.gov (United States)

    2017-03-20

    of frequency L . This problem can be found in many standard quantum optics textbooks e.g [6]. In textbooks , the two states are usually ground and...imprinted” on the atom. Taking into account all three laser pulses, the phase difference then becomes )2()(2)0( TtTtt   , (4a

  19. Single frequency semiconductor lasers

    CERN Document Server

    Fang, Zujie; Chen, Gaoting; Qu, Ronghui

    2017-01-01

    This book systematically introduces the single frequency semiconductor laser, which is widely used in many vital advanced technologies, such as the laser cooling of atoms and atomic clock, high-precision measurements and spectroscopy, coherent optical communications, and advanced optical sensors. It presents both the fundamentals and characteristics of semiconductor lasers, including basic F-P structure and monolithic integrated structures; interprets laser noises and their measurements; and explains mechanisms and technologies relating to the main aspects of single frequency lasers, including external cavity lasers, frequency stabilization technologies, frequency sweeping, optical phase locked loops, and so on. It paints a clear, physical picture of related technologies and reviews new developments in the field as well. It will be a useful reference to graduate students, researchers, and engineers in the field.

  20. Atomic politics

    International Nuclear Information System (INIS)

    Skogmar, G.

    1979-01-01

    The authors basic point is that the military and civil sides of atomic energy cannot be separated. The general aim of the book is to analyze both the military and civil branches, and the interdependence between them, of American foreign policy in the atomic field. Atomic policy is seen as one of the most important imstruments of foreign policy which, in turn, is seen against the background of American imperialism in general. Firstly, the book investigates the most important means by which the United States has controlled the development in the nuclear field in other countries. These means include influencing the conditions of access to nuclear resources of various kinds, influencing the flow of technical-economic information and influencing international organizations and treaties bearing on atomic energy. The time period treated is 1945-1973. 1973 is chosen as the end-year of the study mainly because of the new conditions in the whole energy field initiated by the oil crisis in that year. The sources of the empirical work are mainly hearings before the Joint Committee on Atomic Energy of the U.S. Congress and legal material of various kinds. Secondly, the goals of the American policy are analyzed. The goals identified are armament effect, non-proliferation (horizontal), sales, and energy dependence. The relation between the main goals is discussed.The discussion is centered on the interdependence between the military and the civil aspects, conflict and coincidence of various goals, the relation between short-term and long-term goals, and the possibilities of using one goal as pretext for another. Thirdly, some causes of the changes in the atomic policy around 1953 and 1963 are identified. These are the strategic balance, the competitive situation, the capacity (of the American atomic productive apparatus), and the nuclear technological stage. The specific composition of these four factors at the two time-points can explain the changes of policy. (author)

  1. In Situ Adsorption Studies at the Solid/Liquid Interface: Characterization of Biological Surfaces and Interfaces Using Sum Frequency Generation Vibrational Spectroscopy, Atomic Force Microscopy, and Quartz Crystal Microbalance

    International Nuclear Information System (INIS)

    Phillips, D.C.

    2006-01-01

    Sum frequency generation (SFG) vibrational spectroscopy, atomic force microscopy (AFM), and quartz crystal microbalance (QCM) have been used to study the molecular surface structure, surface topography and mechanical properties, and quantitative adsorbed amount of biological molecules at the solid-liquid interface. The molecular-level behavior of designed peptides adsorbed on hydrophobic polystyrene and hydrophilic silica substrates has been examined as a model of protein adsorption on polymeric biomaterial surfaces. Proteins are such large and complex molecules that it is difficult to identify the features in their structure that lead to adsorption and interaction with solid surfaces. Designed peptides which possess secondary structure provide simple model systems for understanding protein adsorption. Depending on the amino acid sequence of a peptide, different secondary structures (α-helix and β-sheet) can be induced at apolar (air/liquid or air/solid) interfaces. Having a well-defined secondary structure allows experiments to be carried out under controlled conditions, where it is possible to investigate the affects of peptide amino acid sequence and chain length, concentration, buffering effects, etc. on adsorbed peptide structure. The experiments presented in this dissertation demonstrate that SFG vibrational spectroscopy can be used to directly probe the interaction of adsorbing biomolecules with a surface or interface. The use of well designed model systems aided in isolation of the SFG signal of the adsorbing species, and showed that surface functional groups of the substrate are sensitive to surface adsorbates. The complementary techniques of AFM and QCM allowed for deconvolution of the effects of surface topography and coverage from the observed SFG spectra. Initial studies of biologically relevant surfaces are also presented: SFG spectroscopy was used to study the surface composition of common soil bacteria for use in bioremediation of nuclear waste

  2. In Situ Adsorption Studies at the Solid/Liquid Interface:Characterization of Biological Surfaces and Interfaces Using SumFrequency Generation Vibrational Spectroscopy, Atomic Force Microscopy,and Quartz Crystal Microbalance

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Diana Christine [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    Sum frequency generation (SFG) vibrational spectroscopy, atomic force microscopy (AFM), and quartz crystal microbalance (QCM) have been used to study the molecular surface structure, surface topography and mechanical properties, and quantitative adsorbed amount of biological molecules at the solid-liquid interface. The molecular-level behavior of designed peptides adsorbed on hydrophobic polystyrene and hydrophilic silica substrates has been examined as a model of protein adsorption on polymeric biomaterial surfaces. Proteins are such large and complex molecules that it is difficult to identify the features in their structure that lead to adsorption and interaction with solid surfaces. Designed peptides which possess secondary structure provide simple model systems for understanding protein adsorption. Depending on the amino acid sequence of a peptide, different secondary structures (α-helix and β-sheet) can be induced at apolar (air/liquid or air/solid) interfaces. Having a well-defined secondary structure allows experiments to be carried out under controlled conditions, where it is possible to investigate the affects of peptide amino acid sequence and chain length, concentration, buffering effects, etc. on adsorbed peptide structure. The experiments presented in this dissertation demonstrate that SFG vibrational spectroscopy can be used to directly probe the interaction of adsorbing biomolecules with a surface or interface. The use of well designed model systems aided in isolation of the SFG signal of the adsorbing species, and showed that surface functional groups of the substrate are sensitive to surface adsorbates. The complementary techniques of AFM and QCM allowed for deconvolution of the effects of surface topography and coverage from the observed SFG spectra. Initial studies of biologically relevant surfaces are also presented: SFG spectroscopy was used to study the surface composition of common soil bacteria for use in bioremediation of nuclear waste.

  3. Atomic secrecy

    International Nuclear Information System (INIS)

    Sweet, W.

    1979-01-01

    An article, The H-Bomb Secret: How We Got It, Why We're Telling It, by Howard Morland was to be published in The Progressive magazine in February, 1979. The government, after learning of the author's and the editors' intention to publish the article and failing to persuade them to voluntarily delete about 20% of the text and all of the diagrams showing how an H-bomb works, requested a court injunction against publication. Acting under the Atomic Energy Act of 1954, US District Court Judge Robert W. Warren granted the government's request on March 26. Events dealing with the case are discussed in this publication. Section 1, Progressive Hydrogen Bomb Case, is discussed under the following: Court Order Blocking Magazine Report; Origins of the Howard Morland Article; Author's Motives, Defense of Publication; and Government Arguments Against Disclosure. Section 2, Access to Atomic Data Since 1939, contains information on need for secrecy during World War II; 1946 Atomic Energy Act and its effects; Soviet A-Bomb and the US H-Bomb; and consequences of 1954 Atomic Energy Act. Section 3, Disputed Need for Atomic Secrecy, contains papers entitled: Lack of Studies on H-Bomb Proliferation; Administration's Position on H-Bombs; and National Security Needs vs Free Press

  4. Influência da Estrutura de Governança Corporativa na Eficiência Financeira: Evidências de Empresas Brasileiras de Capital Aberto

    Directory of Open Access Journals (Sweden)

    Tatiana Marceda Bach

    2015-12-01

    Full Text Available O agente é responsável por atuar no gerenciamento dos interesses do principal e maximizar os lucros da empresa, com o propósito de coordenar e controlar as atividades realizadas por ambos surge a governança corporativa, visando gerar maiores retornos e eficiência. Este artigo objetiva analisar a influência da governança corporativa na eficiência das empresas de capital aberto listadas na BOVESPA. De natureza quantitativa-descritiva, foram analisados dados de 284 empresas no período de 2008 a 2013. Para o cálculo da eficiência foi utilizado a Análise por Envoltória de Dados (DEA e, para a análise dos dados, utilizou-se o software UNCINET 6.0 e o pacote estatístico STATA versão 11.0. A governança foi avaliada a com base no estudo de Silveira (2004 e com base nas recomendações do código de melhores práticas de Governança Corporativa de agências regulamentadoras. A eficiência dos bancos, ao longo de 6 anos, mostrou-se estável e superior ao das demais empresas. A influência da governança corporativa na eficiência é explicada, para as empresas, pelas variáveis estrutura do conselho e estrutura de propriedade, para os bancos, é explicada pelas variáveis acesso às informações, estrutura do conselho, crescimento da receita e ativo total. Este estudo contribui para a identificação das empresas e bancos eficientes, que a partir deste resultado, podem modificar suas ações e estratégias para aumentar sua eficiência corporativa. Para a governança, as variáveis que se mostraram inversamente proporcionais à eficiência poderiam ser revistas pelas empresas com o propósito de contribuir para um maior crescimento e maximização de seus lucros.

  5. Evaluation of bank efficiency in Brazil: a DEA approach / Avaliação da eficiência bancária brasileira: uma abordagem DEA

    Directory of Open Access Journals (Sweden)

    Patricia Benites Cava

    2017-08-01

    Full Text Available Purpose: The research aims to evaluate the efficiency of banks that operated in the Brazilian market in 2013. To achieve this goal, efficient banks were identified according to the production approach. To detect and explain efficiency standards, additional analyses were carried out related to: 1. capital origin, 2. size, 3. business segment, and 4. risk rating. Originality/gap/relevance/implications: The Brazilian literature on bank efficiency features several studies linking the efficiency of banks to capital origin and size. However, the relationship between efficiency and business segment has been poorly explored and the relationship between efficiency and risk rating is scarce. In this sense, this research contributes to the literature by exploring the relationship between efficiency and business segment, as well as the relationship between efficiency and risk rating. Key methodological aspects: The research uses a quantitative approach and employs the Data Envelopment Analysis (DEA technique to calculate efficiency scores. The data were obtained from the Central Bank of Brazil (Bacen. Summary of key results: Federal public banks and large banks are, on average, more efficient. Banks operating in foreign exchange and retail, as well as banks with high credit ratings, also achieved high levels of efficiency. Key considerations/conclusions: Efficient banks proved to be more profitable, lent less money in proportion to their total assets, and received fewer complaints filed with the Central Bank of Brazil in 2013. Objetivo: A pesquisa tem como objetivo avaliar a eficiência de bancos que atuaram no mercado brasileiro no ano de 2013. Para atingir este objetivo foram identificados os bancos eficientes sob a abordagem de produção. A fim de detectar e explicar padrões de eficiência, foram realizadas análises complementares relacionadas a (1 origem de capital, (2 porte, (3 segmento de atuação e (4 classificação de risco (rating da institui

  6. Antimatter atoms

    International Nuclear Information System (INIS)

    Anon.

    1996-01-01

    In january 1996, CERN broadcasted the information of the creation of nine anti-hydrogen atoms, observed through disintegration products. The experimental facility was CERN LEAR ring. An antiproton beam scattered a xenon jet, and the resulting antimatter was first selected by its insensitivity to beam bending magnets. Their disintegration was detected in thin NaI detectors, in which the anti-atoms are at once deprived from their positron. Then, magnetic and time-of-flight spectrometers are used. (D.L.)

  7. 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

  8. Eficiência hídrica ao nível da redução de perdas

    OpenAIRE

    Reis, Ivone Bastos

    2009-01-01

    O trabalho apresentado surge como resultado da necessidade da implementação do conceito da redução de perdas de água nas preocupações imperativas da sociedade portuguesa. Como tal, enquadra-se na proposta do Programa Nacional para o Uso Eficiente da Água (Resolução do Conselho de Ministros nº 113/2005, de 30/6). Dadas as exigências associadas à eficiência hídrica por parte das entidades governamentais e às questões da disponibilidade do recurso da água, considera-se a necessidade da imp...

  9. Eficiência do uso da radiação em cultivos de milho em Alagoas

    Directory of Open Access Journals (Sweden)

    Ricardo A. Ferreira Junior

    2014-03-01

    Full Text Available O milho foi cultivado em três sistemas de manejo: i cobertura de capim; ii plástico na entrelinha e iii cultivo tradicional (solo nu. Com o objetivo de determinar a eficiência do uso da radiação (EUR mediram-se componentes da radiação solar (incidente e transmitida em dossel de milho. A irradiação fotossintética (HF incidente foi considerada equivalente a 44% da irradiação solar global. A HF transmitida (HFT foi estimada utilizando-se a lei de Beer para radiação aplicada a um dossel vegetal (HFT = HF exp(-k IAF, com coeficiente de extinção da luz (k ajustado de uma função exponencial, que relacionou a fração da HFT (HFT/HF e o índice de área foliar (IAF. A HF interceptada (HFI foi calculada por diferença (HFI = HF - HFT. Estimou-se a EUR por meio de regressão linear, forçada a passar pela origem, entre o acúmulo de matéria seca (MS e a HFI. O k foi de 0,628 com coeficiente de determinação de 0,88. A EUR das plantas da parcela coberta com plástico foi de 3,85 g de MS MJ-1 de HFI, que mostrou eficiência superior à dos demais tratamentos (solo nu 3,31 g MJ-1 e capim 3,58 g MJ-1; entretanto, esta conferiu menor IAF e, consequentemente, teve menos HFI acumulada, o que resultou na menor produção de MS.

  10. Eficiência da adubação nitrogenada do tomateiro em duas épocas de cultivo

    Directory of Open Access Journals (Sweden)

    Magna Maria Macedo Ferreira

    2010-04-01

    Full Text Available A eficiência da adubação nitrogenada do tomateiro, na presença da adubação orgânica, foi avaliada em dois experimentos de campo conduzidos em duas épocas: primavera/verão (nov./98 a fev./99 e outono/primavera (maio/99 a out/99. Os dois experimentos foram instalados na horta da Universidade Federal de Viçosa, em solo da classe Argissolo Vermelho-Amarelo Câmbico. Em ambos, as doses de N aplicadas, na forma de nitrocálcio, foram 0,0; 93,3; 187,0; 374,0; e 748,0 kg/ha, e as doses de adubação orgânica, na forma de esterco bovino curtido, foram 0 e 8 t/ha de matéria seca. Os experimentos seguiram o delineamento em blocos ao acaso, no arranjo fatorial 5 x 2, com quatro repetições. O peso e o número de frutos comercializáveis de tomate, por planta, são aumentados com o aumento do nível de N no solo. A percentagem de frutos comercialmente desclassificáveis é maior na primavera/verão do que no outono/primavera. A eficiência da adubação nitrogenada pelo tomateiro é maior no outono/primavera do que na primavera/verão. Na primavera/verão ela foi maior quando não houve adição de matéria orgânica ao solo, o contrário ocorrendo no outono/primavera.

  11. Eficiência nutricional do milho cv. BRS 1030 submetido à omissão de macronutrientes em solução nutritiva

    Directory of Open Access Journals (Sweden)

    Ancélio Ricardo de Oliveira Gondim

    2010-08-01

    Full Text Available Em casa de vegetação, desenvolveu-se experimento com delineamento inteiramente casualizado, com sete tratamentos e três repetições, a fim de estudar a influência da omissão de nutrientes nas relações de eficiência (eficiência de absorção, translocação e utilização deplantas de milho cv. BRS 1030 crescidas em solução nutritiva de Hoagland & Arnon (1950, completa e com omissão de N, P, K, Ca, Mg e S, durante 30 dias. Após esse período, as plantas foram coletadas, separadas em parte aérea e raiz, secadas e em seguida pesadas e moídas, para determinação dos teores de macronutrientes e obtenção dos índices de eficiência. A omissão de macronutrientes promove diminuição na produção de massa seca da planta inteira e na eficiência de absorção dos nutrientes, quando comparada à do tratamento completo. A omissão de P, Mg e S resulta em maior eficiência de utilização, comparada com o tratamento completo. Plantas deficientes retranslocam os nutrientes, tentando manter seu conteúdo nas folhas medianas (ou parte aérea em relação aos demais órgãos.

  12. Atoms stories

    International Nuclear Information System (INIS)

    Radvanyi, P.; Bordry, M.

    1988-01-01

    Physicists from different countries told each evening during one learning week, to an audience of young people, some great discoveries in evoking the difficulties and problems to which the researchers were confronted. From Antiquity to a more recent history, it is a succession of atoms stories. (N.C.)

  13. Atomic physics

    International Nuclear Information System (INIS)

    Held, B.

    1991-01-01

    This general book describes the change from classical physics to quantum physics. The first part presents atom evolution since antiquity and introduces fundamental quantities and elements of relativity. Experiments which have contributed to the evolution of knowledge on matter are analyzed in the second part. Applications of wave mechanics to the study of matter properties are presented in the third part [fr

  14. 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

  15. Optical angular momentum and atoms

    Science.gov (United States)

    2017-01-01

    Any coherent interaction of light and atoms needs to conserve energy, linear momentum and angular momentum. What happens to an atom’s angular momentum if it encounters light that carries orbital angular momentum (OAM)? This is a particularly intriguing question as the angular momentum of atoms is quantized, incorporating the intrinsic spin angular momentum of the individual electrons as well as the OAM associated with their spatial distribution. In addition, a mechanical angular momentum can arise from the rotation of the entire atom, which for very cold atoms is also quantized. Atoms therefore allow us to probe and access the quantum properties of light’s OAM, aiding our fundamental understanding of light–matter interactions, and moreover, allowing us to construct OAM-based applications, including quantum memories, frequency converters for shaped light and OAM-based sensors. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069766

  16. Push-Pull Laser-Atomic Oscillator

    International Nuclear Information System (INIS)

    Jau, Y.-Y.; Happer, W.

    2007-01-01

    A vapor of alkali-metal atoms in the external cavity of a semiconductor laser, pumped with a time-independent injection current, can cause the laser to self-modulate at the 'field-independent 0-0 frequency' of the atoms. Push-pull optical pumping by the modulated light drives most of the atoms into a coherent superposition of the two atomic sublevels with an azimuthal quantum number m=0. The atoms modulate the optical loss of the cavity at the sharply defined 0-0 hyperfine frequency. As in a maser, the system is not driven by an external source of microwaves, but a very stable microwave signal can be recovered from the modulated light or from the modulated voltage drop across the laser diode. Potential applications for this new phenomenon include atomic clocks, the production of long-lived coherent atomic states, and the generation of coherent optical combs

  17. Atomic spectroscopy with diode lasers

    International Nuclear Information System (INIS)

    Tino, G.M.

    1994-01-01

    Some applications of semiconductor diode lasers in atomic spectroscopy are discussed by describing different experiments performed with lasers emitting in the visible and in the near-infrared region. I illustrate the results obtained in the investigation of near-infrared transitions of atomic oxygen and of the visible intercombination line of strontium. I also describe how two offset-frequency-locked diode lasers can be used to excite velocity selective Raman transitions in Cs. I discuss the spectral resolution, the accuracy of frequency measurements, and the detection sensitivity achievable with diode lasers. (orig.)

  18. Application of Zeeman graphite furnace atomic absorption spectrometry with high-frequency modulation polarization for the direct determination of aluminum, beryllium, cadmium, chromium, mercury, manganese, nickel, lead, and thallium in human blood.

    Science.gov (United States)

    Ivanenko, Natalya B; Solovyev, Nikolay D; Ivanenko, Anatoly A; Ganeev, Alexander A

    2012-10-01

    Determination of aluminum (Al), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), and thallium (Tl) concentrations in human blood using high-frequency modulation polarization Zeeman graphite furnace atomic absorption spectrometry (GFAAS) was performed. No sample digestion was used in the current study. Blood samples were diluted with deionized water or 0.1 % (m/v) Triton X-100 solution for Tl. Dilution factors ranged from 1/5 per volume for Be and Tl to 1/20 per volume for Cd and Pb. For Tl, Cd, and Hg, noble metals (gold, platinum, rhodium, etc.) were applied as surface modifiers. To mitigate chloride interference, 2 % (m/v) solution of NH(4)NO(3) was used as matrix modifier for Tl and Ni assessment. The use of Pd(NO(3))(2) as oxidative modifier was necessary for blood Hg and Tl measurement. Validation of the methods was performed by analyzing two-level reference material Seronorm. The precision of the designed methods as relative SD was between 4 and 12 % (middle of a dynamic range) depending on the element. For additional validation, spiked blood samples were analyzed. Limits of detection (LoDs, 3σ, n = 10) for undiluted blood samples were 2.0 μg L(-1) for Al, 0.08 μg L(-1) for Be, 0.10 μg L(-1) for Cd, 2.2 μg L(-1) for Cr, 7 μg L(-1) for Hg, 0.4 μg L(-1) for Mn, 2.3 μg L(-1) for Ni, 3.4 μg L(-1) for Pb, and 0.5 μg L(-1) for Tl. The LoDs achieved allowed determination of Al, Cd, Cr, Mn, Ni, and Pb at both toxic and background levels. Be, Hg, and Tl could be reliably measured at toxic levels only. The methods developed are used for clinical diagnostics and biological monitoring of work-related exposure.

  19. Quantum Phases of Atom-Molecule Mixtures of Fermionic Atoms

    Science.gov (United States)

    Lopez, Nicolas; Tsai, Shan-Wen

    2009-11-01

    Cold atom experiments have observed atom-molecule mixtures by tuning the interactions between particles.footnotetextM.L. Olsen, J. D. Perreault, T. D. Cumby, and D. S. Jin, Phys. Rev. A 80, 030701(R) (2009) We study many particle interactions by examaning a simple model that describes the destruction of fermionic atom pairs to form single bosonic molecules and vice versa. A set of functional Renomalization Group equationsfootnotetextR. Shankar, Rev. Mod. Phys., Vol 66 No. 1, January 1994^,footnotetextS.W. Tsai, A.H. Castro Neto, R. Shankar, D.K. Campbell, Phys. Rev. B 72, 054531 (2005) describing these processes are set up and solved numerically. The Self Energy of the fermions are attained as a function of frequency and we search for frequency dependent instabilities that could denote a transition from a disordered liquid to a BCS phase. (Financial support from NSF DMR-084781 and UC-Lab Fees Research Program.)

  20. Atom-surface potentials and atom interferometry

    International Nuclear Information System (INIS)

    Babb, J.F.

    1998-01-01

    Long-range atom-surface potentials characterize the physics of many actual systems and are now measurable spectroscopically in deflection of atomic beams in cavities or in reflection of atoms in atomic fountains. For a ground state, spherically symmetric atom the potential varies as -1/R 3 near the wall, where R is the atom-surface distance. For asymptotically large distances the potential is weaker and goes as -1/R 4 due to retardation arising from the finite speed of light. This diminished interaction can also be interpreted as a Casimir effect. The possibility of measuring atom-surface potentials using atomic interferometry is explored. The particular cases studied are the interactions of a ground-state alkali-metal atom and a dielectric or a conducting wall. Accurate descriptions of atom-surface potentials in theories of evanescent-wave atomic mirrors and evanescent wave-guided atoms are also discussed. (author)

  1. Dynamical polarizability of atoms

    International Nuclear Information System (INIS)

    Mukhopadhyay, G.; Lundqvist, S.

    1980-07-01

    The frequency-dependent polarizability of a closed-shell atom is considered in an RPA type approximation. This is usually done using many-body perturbation theory but can also be recast into the form of equations for the density oscillations as previously shown by the authors. The latter approach is known to lead to a non-hermitian problem because of the structure of the interaction kernel. This note shows that this is also true if using the reaction matrix method. The main result is to derive the expression for the polarizability function taking into account the non-hermitian nature of the problem. (author)

  2. Setting efficiency indicators for center pivots Ajuste de indicadores de eficiência para pivôs centrais

    Directory of Open Access Journals (Sweden)

    Ricardo L. Schons

    2012-06-01

    Full Text Available In this study, it was discussed the efficiency criteria in each of the elements that compose a central pivot, and this analysis was applied to two sets of systems located in regions of Cruz Alta and Santo Augusto, state of Rio Grande do Sul, Brazil. The methodology used combines water and energy assessment through an indicator called Normalized Specific Consumption in Irrigation (C ENI, allowing thus a comparison between equipment and projects. The C ENI in Cruz Alta region showed 72% of the equipment above the standard (8.68 kWh mm-1 ha-1 100m-1, and in Santo Augusto region 64.28% with consumption above the standard. The mean irrigation efficiency for Cruz Alta region was 29.85%, with standard deviation of 5.41%, and for Santo Augusto region, it was 29.02%, with standard deviation of 5.15%.Neste trabalho, são discutidos critérios de eficiência em cada um dos elementos que compõem um pivô central, sendo esta análise aplicada a dois conjuntos de sistemas localizados, nas regiões de Cruz Alta e Santo Augusto, Rio Grande do Sul. A metodologia utilizada associa as avaliações hídrica e energética por meio de um indicador denominado Consumo Específico Normalizado na Irrigação (C ENI, possibilitando, desta forma, uma comparação entre equipamentos e entre projetos. O C ENI na região de Cruz Alta apresentou 72% dos equipamentos acima do padrão (8,68 kWh mm-1 ha-1 100m-1, e na região de Santo Augusto, 64,28% com o consumo acima do padrão. A eficiência de irrigação média para a região de Cruz Alta foi de 29,85%, com desvio-padrão de 5,41%; e para a Região de Santo Augusto foi de 29,02%, com desvio padrão de 5,15%.

  3. Exotic atoms

    International Nuclear Information System (INIS)

    Kunselman, R.

    1993-01-01

    The experiments use a solid hydrogen layer to form muonic hydrogen isotopes that escape into vacuum. The method relies on transfer of the muon from protium to either a deuteron or a triton. The resulting muonic deuterium or muonic tritium will not immediately thermalize because of the very low elastic cross sections, and may be emitted from the surface of the layer. Measurements which detect decay electrons, muonic x-rays, and fusion products have been used to study the processes. A target has been constructed which exploits muonic atom emission in order to learn more about the energy dependence of transfer and muon molecular formation

  4. Avaliação da Eficiência Técnica das Empresas de Saneamento Brasileiras Utilizando a Metodologia DEA

    OpenAIRE

    Carmo, Cinthya Melo do

    2003-01-01

    Atualmente, o setor de saneamento básico brasileiro está passando por estudos para modernização das empresas responsáveis pelos serviços d água e captação de esgoto nos âmbitos regionais, estaduais e municipais, a fim de mapear, conhecer a qualidade, amplitude e eficiência desses serviços. Essa dissertação determinou o grau de eficiência técnica das 26 companhias estaduais de saneamento básico, através da metodologia DEA - Análise Envoltória de Dados (Data Envelopment Analys...

  5. Innovation and reliability of atomic standards for PTTI applications

    Science.gov (United States)

    Kern, R.

    1981-01-01

    Innovation and reliability in hyperfine frequency standards and clock systems are discussed. Hyperfine standards are defined as those precision frequency sources and clocks which use a hyperfine atomic transition for frequency control and which have realized significant commercial production and acceptance (cesium, hydrogen, and rubidium atoms). References to other systems such as thallium and ammonia are excluded since these atomic standards have not been commercially exploited in this country.

  6. Three-dimensional atom localization via probe absorption in a cascade four-level atomic system

    Directory of Open Access Journals (Sweden)

    Zeng Wei

    2018-03-01

    Full Text Available For an atomic system with cascade four-level type, a useful scheme about three-dimensional (3D atom localization is proposed. In our scheme the atomic system is coherently controlled by using a radio-frequency field to couple with two-folded levels under the condition of the existence of probe absorption. Our results show that detecting precision of 3D atom localization may be obviously improved by properly adjusting the frequency detuning and strength of the radio-frequency driving field. So our scheme could be helpful to realize 3D atom localization with high-efficiency and high-precision . In the field of laser cooling or the atom nano-lithography, our studies provide potential applications.

  7. Three-dimensional atom localization via probe absorption in a cascade four-level atomic system

    Science.gov (United States)

    Zeng, Wei; Deng, Li; Chen, Aixi

    2018-03-01

    For an atomic system with cascade four-level type, a useful scheme about three-dimensional (3D) atom localization is proposed. In our scheme the atomic system is coherently controlled by using a radio-frequency field to couple with two-folded levels under the condition of the existence of probe absorption. Our results show that detecting precision of 3D atom localization may be obviously improved by properly adjusting the frequency detuning and strength of the radio-frequency driving field. So our scheme could be helpful to realize 3D atom localization with high-efficiency and high-precision . In the field of laser cooling or the atom nano-lithography, our studies provide potential applications.

  8. O desempenho das universidades públicas portuguesas segundo seus alunos: análise de eficiência por meio do Data Envelopment Analysis

    Directory of Open Access Journals (Sweden)

    Emerson Wagner Mainardes

    2012-01-01

    Full Text Available http://dx.doi.org/10.5007/1983-4535.2012v5n1p184   O objetivo desta investigação foi avaliar o desempenho das Universidades Públicas Portuguesas, tomando por base as expectativas e satisfação de seus alunos e utilizando o método DEA (Data Envelopment Analysis. Para atingir o principal objetivo desta investigação, fez-se uma explicação dos conceitos fundamentais para uso do DEA, que mede a eficiência de uma organização ao comparar inputs e outputs. Em seguida, realizou-se uma pesquisa com 1.669 alunos de 55 faculdades de 11 Universidades Públicas Portuguesas, medindo-se os inputs (expectativa e outputs (satisfação. Ao finalizar a análise dos dados, obteve-se as faculdades que demonstram uma boa relação entre a expectativa e satisfação dos alunos, o que pode auxiliar a melhoria da eficiência das faculdades tidas como ineficientes. Constatou-se que o porte da universidade não garante a eficiência. Independente do tamanho, a eficiência no atendimento das expectativas dos alunos pode ser alcançada e o porte da universidade não pode ser justificativa para a ineficiência relativa da organização. Além disso, constatou-se também que uma universidade pode ter faculdades eficientes e outras ineficientes. Portanto, ao invés de unir forças e crescer conjuntamente, determinadas universidades não seguem uma estratégia única, desperdiçando uma de suas principais forças, a capacidade de ser multidisciplinar perseguindo um objetivo único.

  9. Anàlisi de molècules molt eficients per millorar la síntesis orgànica

    OpenAIRE

    Montoya, Vanessa

    2008-01-01

    Mitjançant tècniques experimentals i informàtiques, els autors d'aquest treball van analitzar l'eficiència d'alguns grups de molècules, derivades de compostos de pirazol, usades com a precatalitzadors en els processos de síntesis orgàniques realitzats amb la reacció de Heck.

  10. 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.

  11. Eficiência do mercado de capitais após a adoção da IFRS no Brasil: aplicando o teste de Mishkin

    Directory of Open Access Journals (Sweden)

    Chrystian Tresman Zortea

    2017-08-01

    Full Text Available Este estudo investiga se a eficiência do mercado de capitais brasileiro com relação à incorporação das informações contábeis aos preços se alterou após a adoção das normas internacionais de contabilidade (IFRS. Para tanto, aplica-se o teste de Mishkin (1983 visando testar a hipótese de eficiência de mercado. Os resultados indicam que para o primeiro período de análise (pré-IFRS as variáveis explicativas, componentes do lucro em t tiveram um alto poder em inferir sobre os resultados do lucro futuro em t+1. Entretanto, com os resultados obtidos no teste não foi possível afirmar sobre alguma mudança no cenário da eficiência do mercado acerca das informações contábeis no mercado de capitais após a adoção dos IFRS.

  12. A slow gravity compensated atom laser

    DEFF Research Database (Denmark)

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

    2010-01-01

    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....

  13. Could Atomic clocks be affected by neutrinos?

    CERN Document Server

    Hanafi, Hanaa

    2016-01-01

    An atomic clock is a clock device that uses an electronic transition frequency of the electromagnetic spectrum of atoms as a frequency standard in order to derive a time standard since time is the reciprocal of frequency. If the electronic transition frequencies are in an "optical region", we are talking in this case about optical atomic clocks. If they are in an "microwave region" these atomic clocks are made of the metallic element cesium so they are called Cesium atomic clocks. Atomic clocks are the most accurate time and frequency standards known despite the different perturbations that can affect them, a lot of researches were made in this domain to show how the transitions can be different for different type of perturbations..Since atomic clocks are very sensitive devices, based on coherent states (A coherent state tends to loose coherence after interacting). One question can arise (from a lot of questions) which is why cosmic neutrinos are not affecting these clocks? The answer to this question requir...

  14. Eficiência simbiótica de fungos micorrízicos arbusculares em solo não fumigado, para mamoeiro

    Directory of Open Access Journals (Sweden)

    A. V. Trindade

    2000-09-01

    Full Text Available Para que os fungos micorrízicos arbusculares (FMA possam ser utilizados em um programa de inoculação, é necessário que sejam capazes de apresentar eficiência simbiótica em solo que contenha populações indígenas de FMA. Com o objetivo de avaliar a eficiência simbiótica e o potencial de inoculação de fungos MA em solo não fumigado, para o mamoeiro, foi desenvolvido um experimento em condições de casa de vegetação da Embrapa Mandioca e Fruticultura, Cruz das Almas (BA, utilizando a variedade de mamoeiro Tainung nº 1. Utilizou-se amostra de um Latossolo Amarelo álico que continha 3 mg dm-3 de P disponível e que recebeu doses crescentes de P (0, 20, 40, 80 e 140 mg dm-3, combinadas com inoculação de três espécies previamente selecionadas e três isolados nativos de FMA, obtidos de agrossistema de mamoeiro. As plantas foram inoculadas com solo-inóculo no ato da repicagem e cultivadas por 50 dias, quando se determinaram a colonização, matéria seca da parte aérea e teores de nutrientes nas plantas. Todos os fungos inoculados apresentaram eficiência simbiótica em solo não fumigado, destacando-se Glomus clarum, Gigaspora margarita e isolado 29 (Gigaspora sp., que apresentaram eficiência alta. Os isolados nativos foram mais eficientes em doses mais elevadas de fósforo no solo; a eficiência esteve relacionada com a absorção de fósforo e potássio. Os fungos previamente selecionados em solo fumigado foram também eficientes em solo que continha população indígena de FMA, portanto, validando este procedimento.

  15. Diretrizes para inserção de requisitos de eficiência energética no processo de projeto de aeroportos

    Directory of Open Access Journals (Sweden)

    Fernanda Selistre da Silva Scheidt

    Full Text Available Este artigo aborda a gestão de informação na etapa de projeto visando à consideração de requisitos de eficiência energética em projetos de obras complexas, relatando um estudo de caso em projeto de aeroportos. O atendimento aos requisitos de eficiência energética tende a aumentar ainda mais a complexidade do processo de desenvolvimento do produto (PDP na construção civil. Torna-se necessário, então, buscar instrumentos gerenciais que auxiliem o projetista a analisar as restrições e tradeoffs no PDP ao mesmo tempo em que se considere a agregação de mais valor ao produto, tanto sob o ponto de vista do cliente como do meio ambiente. A decisão de analisar o processo de projeto de aeroportos surgiu pelo fato de essas edificações serem caracterizadas pela complexidade e por apresentarem alto consumo energético e grande impacto ambiental. A partir de uma etapa de revisão bibliográfica, foram identificados os requisitos de eficiência energética a serem considerados na prática de projeto. O estudo teve sequência com a elaboração do macromapeamento do PDP, em um estudo de caso. Os resultados alcançados consistem na análise crítica do PDP e na identificação de oportunidades de inserção dos requisitos de eficiência energética no processo de projeto aeroportuário, considerando as falhas no fluxo de informação entre os agentes envolvidos. Por fim, são apresentadas diretrizes para a inserção dos requisitos de eficiência energética identificados a partir da revisão bibliográfica no processo de projetos de aeroportos.

  16. Laser Spectroscopy and Frequency Combs

    International Nuclear Information System (INIS)

    Hänsch, Theodor W; Picqué, Nathalie

    2013-01-01

    The spectrum of a frequency comb, commonly generated by a mode-locked femtosecond laser consists of several hundred thousand precisely evenly spaced spectral lines. Such laser frequency combs have revolutionized the art measuring the frequency of light, and they provide the long-missing clockwork for optical atomic clocks. The invention of the frequency comb technique has been motivated by precision laser spectroscopy of the simple hydrogen atom. The availability of commercial instruments is facilitating the evolution of new applications far beyond the original purpose. Laser combs are becoming powerful instruments for broadband molecular spectroscopy by dramatically improving the resolution and recording speed of Fourier spectrometers and by creating new opportunities for highly multiplexed nonlinear spectroscopy, such as two-photon spectroscopy or coherent Raman spectroscopy. Other emerging applications of frequency combs range from fundamental research in astronomy, chemistry, or attosecond science to telecommunications and satellite navigation

  17. Atom-atom interactions around the band edge of a photonic crystal waveguide.

    Science.gov (United States)

    Hood, Jonathan D; Goban, Akihisa; Asenjo-Garcia, Ana; Lu, Mingwu; Yu, Su-Peng; Chang, Darrick E; Kimble, H J

    2016-09-20

    Tailoring the interactions between quantum emitters and single photons constitutes one of the cornerstones of quantum optics. Coupling a quantum emitter to the band edge of a photonic crystal waveguide (PCW) provides a unique platform for tuning these interactions. In particular, the cross-over from propagating fields [Formula: see text] outside the bandgap to localized fields [Formula: see text] within the bandgap should be accompanied by a transition from largely dissipative atom-atom interactions to a regime where dispersive atom-atom interactions are dominant. Here, we experimentally observe this transition by shifting the band edge frequency of the PCW relative to the [Formula: see text] line of atomic cesium for [Formula: see text] atoms trapped along the PCW. Our results are the initial demonstration of this paradigm for coherent atom-atom interactions with low dissipation into the guided mode.

  18. Atomic reactor thermal engineering

    International Nuclear Information System (INIS)

    Kim, Gwang Ryong

    1983-02-01

    This book starts the introduction of atomic reactor thermal engineering including atomic reaction, chemical reaction, nuclear reaction neutron energy and soon. It explains heat transfer, heat production in the atomic reactor, heat transfer of fuel element in atomic reactor, heat transfer and flow of cooler, thermal design of atomic reactor, design of thermodynamics of atomic reactor and various. This deals with the basic knowledge of thermal engineering for atomic reactor.

  19. Atomic energy

    International Nuclear Information System (INIS)

    Ramanna, R.

    1978-01-01

    Development of nuclear science in India, particularly the research and development work at the Bhabha Atomic Research Centre (BARC), Bombay, is described. Among the wide range of materials developed for specific functions under rigorous conditions are nuclear pure grade uranium, zirconium and beryllium, and conventional materials like aluminium, carbon steel and stainless steels. Radioisotopes are produced and used for tracer studies in various fields. Various types of nuclear gauges and nuclear instruments are produced. Radiations have been used to develop new high yielding groundnut mutants with large kernals. The sterile male technique for pest control and radiosterilization technique to process potatoes, onions and marine foods for storage are ready for exploitation. Processes and equipment have been developed for production of electrolytic hydrogen, electrothermal phosphorus and desalinated water. Indigenously manufactured components and materials are now being used for the nuclear energy programme. Indian nuclear power programme strategy is to build heavy water reactors and to utilise their byproduct plutonium and depleted uranium to feed fast breeder reactors which will produce more fissile material than burnt. Finally a special mention has been made of the manpower development programme of the BARC. BARC has established a training school in 1957 giving advanced training in physics, chemistry and various branches of engineering and metallurgy

  20. Eficiência dos dialelos circulantes na escolha de genitores Efficiency of circulant diallels in parental choice

    Directory of Open Access Journals (Sweden)

    RUBEN DELLY VEIGA

    2000-07-01

    Full Text Available O objetivo foi avaliar, por simulação de dados, a eficiência de dialelos circulantes em relação aos completos, nas estimativas de capacidade geral de combinação (CGC e capacidade específica de combinação (CEC. Foram simuladas 50 linhagens com 100 genes com distribuição independente, efeitos iguais, sem epistasia. Consideraram-se herdabilidades de 10%, 20%, 50% e 75%, em modelos com interação alélica aditiva e dominância completa. Utilizaram-se também dados de experimentos disponíveis na literatura, ambos comparados por meio de: correlação entre estimativas de CGC e CEC, e proporções de estimativas nos circulantes que ocorreram nos intervalos de confiança dos completos. Os resultados permitiram concluir que os dialelos circulantes são tão eficientes quanto os completos, tanto na classificação dos pais quanto à CGC e à CEC, como na magnitude desses parâmetros, e que o número de cruzamentos (s afeta as estimativas de CGC e de CEC, embora com um valor pequeno de s seja possível obter boa concordância com as estimativas obtidas nos dialelos completos; com baixa herdabilidade, é vantajoso aumentar o número de cruzamentos de cada pai, embora com a metade do número de pais envolvidos já se consiga alta eficiência dos dialelos circulantes.This paper aimed to evaluate the efficiency of circulant diallel in relation to the complete ones, with data simulation based on estimates of general combining ability (GCA and specific combining ability (SCA. Fifty lines with 100 independent genes of same effects and without epistasy were simulated. Heritabilities of 10%, 20%, 50% and 75% were considered, in models with addictive and complete dominant allelic interaction. Real data experiments presented in literature were used. They were compared by means of correlation between estimates of GCA and SCA, and also by means of proportions of estimates in the circulant that occurred in the confidence intervals of the complete ones. It

  1. Eficiência relativa de fertilizantes fosfatados no crescimento inicial de eucalipto cultivado em solos do cerrado

    Directory of Open Access Journals (Sweden)

    J.L. Gava

    1997-09-01

    Full Text Available Tendo como objetivo avaliar a eficiência relativa do superfosfato simples (SS, fosfato parcialmente acidulado (FAPS e termofosfato magnesiano (TERM como fonte de P e outros nutrientes para o cultivo de plantações de eucalipto, em dois solos da região dos Cerrados, uma areia quartzosa (50 g kg-1 de argila álica e um latossolo vermelho-escuro (230 g kg-1 de argila álico, foi realizado este experimento, sob condições de casa de vegetação, na ESALQ/USP, Piracicaba (SP, em 1993. Subamostras do AQ receberam 0, 75, 150 e 300 mg kg-1 de P e, do LE, 0, 125, 250 e 500 mg kg-1 de P no solo. As doses de P foram estimadas com base na solubilidade dos adubos; SS e FAPS, em citrato de amônio, e TERM, em ácido cítrico 20 g L-1. Em cada vaso (5 kg de solo, deixou-se uma planta de Eucalyptus grandis por 90 dias após a emergência e desbaste das plântulas. Paralelamente ao experimento em casa de vegetação, subamostras de todos os tratamentos, com 2 kg de solo, foram incubadas no interior de sacos plásticos por 0, 10, 20, 40, 60 e 80 dias. Ao término de cada período de incubação, os solos eram amostrados e analisados. Mediante o cálculo de índices de eficiência relativa entre os adubos, verificou-se que o TERM foi superior 64% ao SS e 57% ao FAPS no solo AQ. No LE, o SS foi superior 55% ao TERM e 34% ao FAPS. O TERM foi a fonte de P que promoveu os maiores acréscimos do nível de fertilidade dos solos, com expressiva elevação do pH do solo, redução das concentrações de Al e aumento daquelas de Ca e Mg. Os ganhos de produção das mudas de eucalipto foram altamente correlacionados com a absorção de P, K, Ca, Mg e Zn. O TERM proporcionou as maiores absorções desses nutrientes no solo AQ e, as menores, de P, Ca e Zn no LE. As distintas respostas de crescimento para os adubos avaliados, em ambos os solos, sobretudo para TERM e SS, foram atribuídas, em grande parte, aos efeitos secundários das fontes de P sobre a fertilidade dos

  2. Eficiência de extratos vegetais no controle de Diabrotica speciosa (Germar, 1824 (Coleoptera: Chrysomelidae, em laboratório

    Directory of Open Access Journals (Sweden)

    Junir Antonio Lutinski

    2010-04-01

    Full Text Available http://dx.doi.org/10.5007/2175-7925.2010v23n1p83 Vulgarmente conhecida como “vaquinha”, Diabrotica speciosa (Germar, 1824 ocorre na maioria dos estados brasileiros, destacando-se como uma das mais importantes pragas do feijoeiro e do milho. Visando avaliar a atividade inseticida de extratos brutos aquosos de nove espécies vegetais sobre os adultos deste inseto, realizou-se este trabalho. O experimento, conduzido em laboratório, foi realizado sob delineamento completamente casualizado, com dez tratamentos e quatro repetições. Para tal, utilizou-se um frasco, contendo em seu interior cinco espécimes adultos e uma folha de feijoeiro (Phaseolus vulgaris Linnaeus previamente imersa no extrato, tampado com um recorte de pano poroso e fixado por uma borracha. A variável avaliada foi número de espécimes de D. speciosa vivos. Os tratamentos consistiram em extratos de salvia (Salvia officinalis Linnaeus, cravo (Eugenia caryophyllata Thunb, noz-moscada (Myristica fragans Houtt, cinamomo (Melia azedarach Linnaeus, timbó (Ateleia glazioveana Baill, eucalipto (Eucalyptus citriodora Hook, canela (Cinnamomum zeylanicum Blume, figueira (Ficus microcarpa Linnaeus f., alecrim (Rosmarinus officinalis Linnaeus e a testemunha (apenas água destilada. As avaliações de sobrevivência foram realizadas a cada 24 horas, durante 10 dias. Sobre o número de espécimes vivos efetuou-se a análise de variância em bifatorial (10 extratos x 11 horários após a aplicação. As médias foram agrupadas pelo teste de Duncan ao nível de 5% de probabilidade de erro. Os extratos mais eficientes foram o timbó, noz-moscada e cinamomo, com porcentagens de eficiência variando entre 80,4% e 100%.

  3. Atom localization via controlled spontaneous emission in a five-level atomic system

    International Nuclear Information System (INIS)

    Wang Zhiping; Yu Benli; Zhu Jun; Cao Zhigang; Zhen Shenglai; Wu Xuqiang; Xu Feng

    2012-01-01

    We investigate the one- and two-dimensional atom localization behaviors via spontaneous emission in a coherently driven five-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of atom localization behaviors can be significantly improved via adjusting the system parameters. More importantly, the two-dimensional atom localization patterns reveal that the maximal probability of finding an atom within the sub-wavelength domain of the standing waves can reach unity when the corresponding conditions are satisfied. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization. - Highlights: ► One- and two-dimensional atom localization behaviors via spontaneous emission in five-level atoms are investigated. ► An assisting radio-frequency field is used to control the atom localization behaviors. ► High-precision and high-resolution two-dimensional atom localization can be realized in this scheme.

  4. Trapping of Rydberg atoms in tight magnetic microtraps

    NARCIS (Netherlands)

    Boetes, A.Q.G.; Skannrup, R.V.; Naber, J.; Kokkelmans, S.J.J.M.F.; Spreeuw, R.J.C.

    2018-01-01

    We explore the possibility to trap Rydberg atoms in tightly confining magnetic microtraps. The trapping frequencies for Rydberg atoms are expected to be influenced strongly by magnetic-field gradients. We show that there are regimes where Rydberg atoms can be trapped. Moreover, we show that

  5. Active Faraday optical frequency standard.

    Science.gov (United States)

    Zhuang, Wei; Chen, Jingbiao

    2014-11-01

    We propose the mechanism of an active Faraday optical clock, and experimentally demonstrate an active Faraday optical frequency standard based on narrow bandwidth Faraday atomic filter by the method of velocity-selective optical pumping of cesium vapor. The center frequency of the active Faraday optical frequency standard is determined by the cesium 6 (2)S(1/2) F=4 to 6 (2)P(3/2) F'=4 and 5 crossover transition line. The optical heterodyne beat between two similar independent setups shows that the frequency linewidth reaches 281(23) Hz, which is 1.9×10(4) times smaller than the natural linewidth of the cesium 852-nm transition line. The maximum emitted light power reaches 75 μW. The active Faraday optical frequency standard reported here has advantages of narrow linewidth and reduced cavity pulling, which can readily be extended to other atomic transition lines of alkali and alkaline-earth metal atoms trapped in optical lattices at magic wavelengths, making it useful for new generation of optical atomic clocks.

  6. Hydrogen-like atom in laser field: Invariant atomic parameters in the ground state

    International Nuclear Information System (INIS)

    Bondarev, I.V.; Kuten, S.A.

    1994-07-01

    The invariant atomic parameters (dynamical vector and tensor polarizabilities) of hydrogen-like atom in the ground 1S 1/2 state are calculated analytically by means of the Laplace transform of the radial Schroedinger equation. The obtained analytical expressions have been written in the compact form as a sum of linear and squared combinations of Gauss hypergeometric functions 2 F 1 . The frequency dependence of the invariant atomic parameters is analyzed. (author). 24 refs, 1 fig

  7. Atomic weight versus atomic mass controversy

    International Nuclear Information System (INIS)

    Holden, N.E.

    1985-01-01

    A problem for the Atomic Weights Commission for the past decade has been the controversial battle over the names ''atomic weight'' and ''atomic mass''. The Commission has considered the arguments on both sides over the years and it appears that this meeting will see more of the same discussion taking place. In this paper, I review the situation and offer some alternatives

  8. The SILVA atomic process

    International Nuclear Information System (INIS)

    Cazalet, J.

    1996-01-01

    The SILVA isotopic laser separation process of atomic uranium vapor requires the use of specific high power visible light laser devices and systems for uranium evaporation and management (separation modules). The CEA, in collaboration with industrialists, has developed these components and built some demonstration plants. The scientific and technological challenges raised by this process are now surmounted. The principle of the SILVA process is the selective photo-ionization of uranium isotopes using laser photon beams tuned to the exact excitation frequency of the isotope electron layers. This paper describes the principle of the SILVA process (lasers and separator), the technical feasibility and actual progress of the program and its future steps, its economical stakes, and the results obtained so far. (J.S.). 2 figs., 2 photos

  9. Frequency standards

    CERN Document Server

    Riehle, Fritz

    2006-01-01

    Of all measurement units, frequency is the one that may be determined with the highest degree of accuracy. It equally allows precise measurements of other physical and technical quantities, whenever they can be measured in terms of frequency.This volume covers the central methods and techniques relevant for frequency standards developed in physics, electronics, quantum electronics, and statistics. After a review of the basic principles, the book looks at the realisation of commonly used components. It then continues with the description and characterisation of important frequency standards

  10. Avaliação das consequências da implementação de medidas de eficiência hídrica no consumo de água, na eficiência energética e nas emissões de CO2: caso de estudo numa habitação unifamiliar

    OpenAIRE

    Moura, Tatiana Ferreira

    2015-01-01

    Dissertação de Mestrado em Engenharia Civil A água é um bem essencial para as populações e tem vindo a tornar-se um recurso natural cada vez mais escasso devido ao estilo de vida cada mais consumista, o que aliado às alterações no regime de precipitação, pode agravar a situação de stress hídrico. Assim, é necessário promover a eficiência hídrica de modo a atenuar esta situação. A implementação de diversas medidas de eficiência hídrica poderá levar a reduções até 30% no consu...

  11. Highly excited atoms

    International Nuclear Information System (INIS)

    Kleppner, D.; Littman, M.G.; Zimmerman, M.L.

    1981-01-01

    Highly excited atoms are often called Rydberg atoms. These atoms have a wealth of exotic properties which are discussed. Of special interest, are the effects of electric and magnetic fields on Rydberg atoms. Ordinary atoms are scarcely affected by an applied electric or magnetic field; Rydberg atoms can be strongly distorted and even pulled apart by a relatively weak electric field, and they can be squeezed into unexpected shapes by a magnetic field. Studies of the structure of Rydberg atoms in electric and magnetic fields have revealed dramatic atomic phenomena that had not been observed before

  12. Laser-assisted atom-atom collisions

    International Nuclear Information System (INIS)

    Roussel, F.

    1984-01-01

    The basic layer-assisted atom-atom collision processes are reviewed in order to get a simpler picture of the main physical facts. The processes can be separated into two groups: optical collisions where only one atom is changing state during the collision, the other acting as a spectator atom, and radiative collisions where the states of the two atoms are changing during the collision. All the processes can be interpreted in terms of photoexcitation of the quasimolecule formed during the collisional process. (author)

  13. Avaliação da eficiência energética em uma indústria de painéis compensado

    OpenAIRE

    Silva, Dimas Agostinho da

    2013-01-01

    Este trabalho trata do perfil e do uso de energia em uma indústria de painéis compensado no Brasil. O seu objetivo geral é corroborar para a melhoria da competitividade da indústria de compensado nacional. Especificamente visou conhecer o perfil do consumo energético na indústria, avaliar possibilidade de ganhos de eficiência no componente energético do processo produtivo e disponibilizar modelos matemáticos de consumo energético aplicado às indústrias de painéis compensado. O trabalho foi de...

  14. Eficiência Bionutricional de Animais da Raça Nelore e seus Mestiços com Caracu, Angus e Simental

    Directory of Open Access Journals (Sweden)

    Euclides Filho Kepler

    2002-01-01

    Full Text Available Foram avaliados 23 machos inteiros de três grupos genéticos, sete da raça Nelore (N, oito ½ Caracu + ¼ Angus + ¼ Nelore (CCAN e oito ½ Caracu + ¼ Simental + ¼ Nelore (CCSN. Esses animais pertenciam a um projeto em desenvolvimento na Embrapa Gado de Corte, com o objetivo de identificar um grupo genético que, além de ser adaptado às condições tropicais e subtropicais, produza carne de qualidade de forma eficiente e competitiva (Projeto composto Indo-Euro. O presente experimento teve como objetivo específico avaliar a eficiência bionutricional desses animais. Para tanto, as variáveis ganho de peso e consumo de matéria seca foram consideradas simultaneamente em uma análise bivariada. Utilizando o maior autovalor, estabeleceu-se a primeira função discriminante canônica que foi usada para a obtenção da eficiência bionutricional. A análise estatística revelou efeito significativo de grupo genético sobre essa eficiência. As médias foram comparadas por meio dos seguintes contrastes: C1 CCAN versus CCSN; e C2 média dos animais CCAN e CCSN versus N. Como os dois contrastes foram significativos, concluiu-se haver diferenças entre os desempenhos nutricionais dos animais mestiços, e que os animais CCANs apresentaram melhor EBN do que os CCSNs (60,72 versus 48,63, respectivamente. Os mestiços apresentaram melhor eficiência do que os nelores (54,67 versus 16,70. As médias de quadrados mínimos para consumo de matéria seca diário e para ganho de peso médio diário, durante o período de avaliação, foram, respectivamente: 7,62 kg e 1 kg; 7,19 kg e 1,23 kg e 7,57 kg e 1,15 kg para os animais N, CCAN e CCSN.

  15. Avaliação da eficiência das passagens para peixes através de detectores de infravermelhos. Riverwatcher: um caso de estudo

    OpenAIRE

    Pinheiro, Paulo J.; Santos, José M.; Ferreira, M.T.; Bochechas, Jorge

    2003-01-01

    A eficiência de uma passagem para peixes de bacias sucessivas instalada na mini-hídrica de Janeiro de Cima, no rio Zêzere, foi avaliada utilizando um dispositivo de leitura de infravermelhos, o Riverwatcher. Este aparelho funciona como um “bio-scanner ”, cuja função é a contagem do número de peixes que transpõem os leitores de infravermelhos do dispositivo, registando além de dados ambientais como a temperatura da água, variáveis como o comprimento e silhueta dos peixes. Foram ...

  16. Eficiência do aguapé sobre variáveis limnológicas em canais de abastecimento utilizados no cultivo de tambaqui

    OpenAIRE

    Silva, Alinne Dué Ramos da; Santos, Robson Batista dos; Bruno, Arthur Murilo da Silva Souza; Gentelini, André Luis; Silva, Ana Helena Gomes da; Soares, Emerson Carlos

    2014-01-01

    O uso de macrófitas aquáticas pode ser uma alternativa para o tratamento e minimização dos efluentes gerados na piscicultura. Objetivou-se com este trabalho verificar a eficiência do aguapé (Eichhornia crassipes) na melhora de variáveis limnológicas (fósforo e amônia) com cultivo de tambaqui (Colossoma macropomum) em canais com fluxo contínuo de água. O experimento foi conduzido por um período de 60 dias com amostragens quinzenais em canais de abastecimento, seccionados com telas e utilizando...

  17. Desenvolvimento de uma ferramenta para análise da eficiência global de um equipamento numa instalação de fabrico de cerveja

    OpenAIRE

    Marques, Luís Daniel Correia

    2017-01-01

    Trabalho final de mestrado para obtenção do grau de Mestre em Engenharia Mecânica Num mundo dominado pela competitividade industrial, a qualidade e disponibilidade dos ativos físicos representa um papel preponderante na subsistência das organizações. A implementação da filosofia Total Productive Maintenance (TPM) objetiva a diminuição de defeitos e permite que seja alcançada a máxima eficiência através da otimização da disponibilidade, qualidade e desempenho. A Manutenção Produtiva Total é...

  18. Eficiência dos testes cromáticos de comparação na discromatopsia hereditária: relato de casos

    OpenAIRE

    Fernandes,Luciene Chaves; Urbano,Lúcia Carvalho de Ventura

    2008-01-01

    As autoras relatam dois casos de discromatopsia hereditária e discutem a eficiência dos testes cromáticos no diagnóstico de uma discromatopsia. Os pacientes foram reprovados em diferentes concursos públicos federais por apresentarem diagnóstico de discromatopsia hereditária pelo teste de Ishihara. Submeteram-se a exame oftalmológico, com resultados dentro da normalidade. Procuraram novo parecer para melhor caracterização da sua discromatopsia. Não havia sintomas relacionados à deficiência. Os...

  19. Relação entre os caracteres determinantes das eficiências no uso de nitrogênio e fósforo em milho

    Directory of Open Access Journals (Sweden)

    Felipe Bermudez Pereira

    2013-10-01

    Full Text Available O melhoramento genético das eficiências no uso de N (EUN e P (EUP é um dos meios para se obterem produtividades de grãos satisfatórias, com menores custos e de modo sustentável. Todavia, pouco se sabe a respeito da relação entre os caracteres determinantes dessas eficiências, o que tem dificultado o uso da seleção precoce e indireta. Portanto, objetivou-se, com este trabalho, identificar a relação entre os caracteres determinantes das eficiências no uso de nitrogênio e fósforo, em milho. Para isso, avaliaram-se 14 linhagens e 39 híbridos simples, em dois experimentos, em baixa e alta disponibilidade de N e P, em delineamento inteiramente ao acaso, com duas repetições, em esquema fatorial simples. Os experimentos foram conduzidos em telado. Foram utilizados tubos cilíndricos de PVC, com 4 dm³ de capacidade, preenchidos com dois tipos de substrato, de acordo com o experimento. As soluções nutritivas foram fornecidas a partir do sétimo dia após o transplantio, aplicando-se 250 ml tubo-1, a cada dois dias. As plantas foram colhidas em estádio de seis folhas completamente expandidas (V6 e os caracteres avaliados foram: massa da parte aérea seca (MPS, área de raiz específica (ARE, comprimento de raízes laterais (CRLat e axiais (CRAxi e os dois componentes da EUN e EUP, as eficiências de utilização (EUt e a de absorção (EAb. Foram realizadas análises de variância e de trilha dos dados coletados. Os caracteres de raiz não apresentaram efeitos significativos sobre as EUN e EUP. A MPS é o principal determinante das EUN e EUP, independentemente da disponibilidade nutricional.

  20. Um modelo para a avaliação da eficiência hídrica em edifícios

    OpenAIRE

    Rodrigues, Carla Andreia Pimentel

    2015-01-01

    A presente dissertação tem como objetivo o desenvolvimento de um modelo para a avaliação da eficiência hídrica de edifícios, à semelhança do já existente noutras especialidades da construção, como é o caso da energia. O desenvolvimento deste modelo integra-se no quadro das preocupações da sociedade atual, no sentido de alargar a todos os sectores as medidas de sustentabilidade ambiental. Embora o esquema proposto se dirija essencialmente a edifícios do tipo residencial, ele ...

  1. Eficiência simbiótica de estirpes de Cupriavidus necator tolerantes a zinco, cádmio, cobre e chumbo

    Directory of Open Access Journals (Sweden)

    Paulo Ademar Avelar Ferreira

    2012-01-01

    Full Text Available O objetivo deste trabalho foi avaliar a tolerância de estirpes de Cupriavidus necator a zinco, cádmio, cobre e chumbo, além de determinar a eficiência simbiótica das estirpes mais tolerantes em associação a espécies leguminosas com potencial para revegetação. A tolerância foi testada em meio LB, suplementado com 2,5; 5,0; 7,5; 10; 12,5 e 15 mmol L-1 de ZnSO4.7H2O, CdSO4.8H2O, CuSO4.5H2O e PbCl2, respectivamente, em comparação ao controle sem adição de metal. Determinou-se a eficiência simbiótica das quatro estirpes de C. necator mais tolerantes aos metais avaliados (UFLA02-71, UFLA02-73, UFLA01-659 e UFLA01-663, as quais foram inoculadas nas espécies: Leucaena leucocephala, Enterolobium contortisiliquum, Acacia mangium, Mimosa caesalpiniifolia, M. pudica, M. pigra e M. acutistipula. Em vasos com solos, avaliaram-se L. leucocephala, M. pudica e M. caesalpiniifolia e as estirpes UFLA01-659 e UFLA02-71, selecionadas na avaliação de eficiência simbiótica. A estirpe UFLA02-71 proporcionou incrementos de matéria seca da parte aérea de 870% em M. caesalpiniifolia, enquanto que UFLA01-659 proporcionou 885% em M. pudica e 924% em L. leucocephala. As estirpes UFLA01-659 e UFLA02-71, além da alta tolerância a metais pesados, apresentaram eficiência em fixar nitrogênio, em simbiose com essas leguminosas, em solos com rizóbios nativos capazes de nodulá-las, e devem ser avaliadas quanto ao seu potencial de utilização em programas de recuperação de áreas degradadas.

  2. Cold atoms in optical cavities and lattices

    International Nuclear Information System (INIS)

    Horak, P.

    1996-11-01

    The thesis is organized in three chapters covering different aspects of the interaction of atoms and light in the framework of theoretical quantum optics. In chapter 1 a special case of a microscopic laser where one or two atoms interact with several quantized cavity modes is discussed. In particular I investigate the properties of the light field created in one of the cavity modes. It is shown that a single-atom model already predicts average photon numbers in agreement with a semiclassical many-atom theory. The two-atom model exhibits additional collective features, such as superradiance and subradiance. In chapter 2 effects of the photon recoil on cold atoms in the limit of long-lived atomic transitions are investigated. First, I demonstrate that, in principle, relying on this scheme, a continuous-wave laser in the ultraviolet frequency domain could be established. Second, the splitting of an atomic beam into two coherent subbeams is discussed within the same scheme. Such beamsplitters play an important role in high-precision measurements using atomic interferometers. Finally, chapter 3 deals with cooling and trapping of atoms by the interaction with laser light. I discuss the properties and the light scattering of atoms trapped in a new light field configuration, a so-called dark optical superlattice. In principle, such systems allow the trapping of more than one atom in the ground state of a single optical potential well. This could give rise to the observation of e.g. atom-atom interactions and quantum statistical effects. (author)

  3. Code ATOM for calculation of atomic characteristics

    International Nuclear Information System (INIS)

    Vainshtein, L.A.

    1990-01-01

    In applying atomic physics to problems of plasma diagnostics, it is necessary to determine some atomic characteristics, including energies and transition probabilities, for very many atoms and ions. Development of general codes for calculation of many types of atomic characteristics has been based on general but comparatively simple approximate methods. The program ATOM represents an attempt at effective use of such a general code. This report gives a brief description of the methods used, and the possibilities of and limitations to the code are discussed. Characteristics of the following processes can be calculated by ATOM: radiative transitions between discrete levels, radiative ionization and recombination, collisional excitation and ionization by electron impact, collisional excitation and ionization by point heavy particle (Born approximation only), dielectronic recombination, and autoionization. ATOM explores Born (for z=1) or Coulomb-Born (for z>1) approximations. In both cases exchange and normalization can be included. (N.K.)

  4. Frequency Synthesiser

    NARCIS (Netherlands)

    Drago, Salvatore; Sebastiano, Fabio; Leenaerts, Dominicus M.W.; Breems, Lucien J.; Nauta, Bram

    2016-01-01

    A low power frequency synthesiser circuit (30) for a radio transceiver, the synthesiser circuit comprising: a digital controlled oscillator configured to generate an output signal having a frequency controlled by an input digital control word (DCW); a feedback loop connected between an output and an

  5. Frequency synthesiser

    NARCIS (Netherlands)

    Drago, S.; Sebastiano, Fabio; Leenaerts, Dominicus Martinus Wilhelmus; Breems, Lucien Johannes; Nauta, Bram

    2010-01-01

    A low power frequency synthesiser circuit (30) for a radio transceiver, the synthesiser circuit comprising: a digital controlled oscillator configured to generate an output signal having a frequency controlled by an input digital control word (DCW); a feedback loop connected between an output and an

  6. Intake and feeding efficiency in feed-lot lambs Consumo e Eficiência Alimentar em Cordeiros Confinados

    Directory of Open Access Journals (Sweden)

    Joadil Gonçalves Abreu

    2008-12-01

    Full Text Available The present experiment was carried out in order to evaluate the intake and feed efficiency in fed-lot sheep as function of the body weight (BW variation. Data from three experiments with 50 feedlot lambs maintained in individual metabolic cages and fed diets composed of 50:50 roughage:concentrate were used. The experiment lasted 120 days; every 21 days the animals were weighed and the dry matter intake and body weight change were daily done. The intake was determined by checking daily the feed offer level and orts. The increased in animals body weight incremented the dry matter intake in 30.8g/kg of body weight/day, but promoted reduction of 0.0318% when the intake was expressed as percentage of BW. In addition, the advance of body weight affected negatively the feed conversion (FC, where animals with BW of 30 kg showed estimated FC of 4.55 of dry matter/kg of BW gain, while animals with BW of 45 kg have would food conversion of 7.03 kg of DM/kg of BW gain.Este trabalho foi realizado com o objetivo de avaliar o consumo e a eficiência alimentar em ovinos confinados em função da variação no peso vivo (PV. Foram utilizados dados de três experimentos com cordeiros em confinamento, 50 animais no total, mantidos em gaiolas individuais para estudos de metabolismo, alimentados com dietas de relação volumoso: concentrado 50:50. Durante o experimento (120 dias, os animais foram monitorados quanto ao consumo diário de matéria seca e à variação de peso vivo, por meio de pesagens realizadas a cada 21 dias. O consumo foi determinado pelo monitoramento diário da oferta de alimento e das sobras. Com o do peso vivo dos animais aumentou o consumo de matéria seca em 29,38g/kg de PV/dia, mas promoveu redução de 0,0318% quando expresso em porcentagem do PV. Além disso, o avanço do PV afetou negativamente a conversão alimentar (CA, de modo que animais com 30kg de PV apresentaram CA estimada de 4,55kg de MS/kg de PV ganho, enquanto animais com peso

  7. Optical lattice clock with strontium atoms; Horloge a reseau optique a atomes de strontium

    Energy Technology Data Exchange (ETDEWEB)

    Baillard, X.; Le Targat, R.; Fouche, M.; Brusch, A.; Westergaard, Ph.G.; Lecallier, A.; Lodewyck, J.; Lemonde, P. [Observatoire de Paris, LNE-SYRTE, Systemes de Reference Temps Espace, 75 (France)

    2009-07-01

    Optical lattice clocks, which were first imagined in 2000, should allow one to achieve unprecedented performances in the domain of atomic clocks. We present here the Strontium lattice clock, developed at LNE-SYRTE. The principle, in particular trapping atoms in the Lamb-Dicke regime and the notion of magic wavelength, is first explained. We then present the results obtained for the {sup 87}Sr isotope, with a frequency accuracy of 2,6.10{sup -15}, and the {sup 88}Sr isotope, with. which we perform the first frequency measurement of an optical lattice clock with bosonic atoms. (authors)

  8. High-speed cinematography of gas-metal atomization

    Energy Technology Data Exchange (ETDEWEB)

    Ting, Jason [ALCOA Specialty Metals Division, 100 Technical Drive, Alcoa Center, PA 15069 (United States)]. E-mail: jason.ting@alcoa.com; Connor, Jeffery [Material Science Engineering Department, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Ridder, Stephen [Metallurgical Processing Group, NIST, 100 Bureau Dr. Stop 8556, Gaithersburg, MD 20899 (United States)

    2005-01-15

    A high-speed cinematographic footage of a 304L stainless steel gas atomization, recorded at the National Institute of Standard and Technology (NIST), was analyzed using a discrete Fourier transform (DFT) algorithm. The analysis showed the gas atomization process possesses two prominent frequency ranges of melt oscillation (pulsation). A low-frequency oscillation in the melt flow occurring between 5.41 and 123 Hz, with a dominant frequency at 9.93 Hz, was seen in the recirculation zone adjacent to the melt orifice. A high-frequency melt oscillation range was observed above 123 Hz, and was more prominent one melt-tip-diameter downstream in the melt atomization image than upstream near the melt tip. This high-frequency range may reflect the melt atomization frequency used to produce finely atomized powder. This range also included a prominent high frequency at 1273 Hz, which dominated in the image further away downstream from the melt tip. This discrete high-frequency oscillation is most probably caused by the aeroacoustic ''screech'' phenomenon, intrasound (<20 kHz), a result of the atomizing gas jets undergoing flow resonance. It is hypothesized that this discrete intrinsic aeroacoustic tone may enhance melt breakup in the atomization process with evidence of this fact in the melt images.

  9. High-speed cinematography of gas-metal atomization

    International Nuclear Information System (INIS)

    Ting, Jason; Connor, Jeffery; Ridder, Stephen

    2005-01-01

    A high-speed cinematographic footage of a 304L stainless steel gas atomization, recorded at the National Institute of Standard and Technology (NIST), was analyzed using a discrete Fourier transform (DFT) algorithm. The analysis showed the gas atomization process possesses two prominent frequency ranges of melt oscillation (pulsation). A low-frequency oscillation in the melt flow occurring between 5.41 and 123 Hz, with a dominant frequency at 9.93 Hz, was seen in the recirculation zone adjacent to the melt orifice. A high-frequency melt oscillation range was observed above 123 Hz, and was more prominent one melt-tip-diameter downstream in the melt atomization image than upstream near the melt tip. This high-frequency range may reflect the melt atomization frequency used to produce finely atomized powder. This range also included a prominent high frequency at 1273 Hz, which dominated in the image further away downstream from the melt tip. This discrete high-frequency oscillation is most probably caused by the aeroacoustic ''screech'' phenomenon, intrasound (<20 kHz), a result of the atomizing gas jets undergoing flow resonance. It is hypothesized that this discrete intrinsic aeroacoustic tone may enhance melt breakup in the atomization process with evidence of this fact in the melt images

  10. Atomic fountain and applications

    International Nuclear Information System (INIS)

    Rawat, H.S.

    2000-01-01

    An overview of the development of working of MOT along with the basic principle of laser atom cooling and trapping is given. A technique to separate the cooled and trapped atoms from the MOT using atomic fountain technique will also be covered. The widely used technique for atomic fountain is, first to cool and trap the neutral atoms in MOT and then launch them in the vertical direction, using moving molasses technique. Using 133 Cs atomic fountain clock, time improvement of 2 to 3 order of magnitude over a conventional 133 Cs atomic clock has been observed

  11. Interferometry with atoms

    International Nuclear Information System (INIS)

    Helmcke, J.; Riehle, F.; Witte, A.; Kisters, T.

    1992-01-01

    Physics and experimental results of atom interferometry are reviewed and several realizations of atom interferometers are summarized. As a typical example of an atom interferometer utilizing the internal degrees of freedom of the atom, we discuss the separated field excitation of a calcium atomic beam using four traveling laser fields and demonstrate the Sagnac effect in a rotating interferometer. The sensitivity of this interferometer can be largely increased by use of slow atoms with narrow velocity distribution. We therefore furthermore report on the preparation of a laser cooled and deflected calcium atomic beam. (orig.)

  12. Cold atomic beams of high brightness

    International Nuclear Information System (INIS)

    Rozhdestvensky, Yu V

    2004-01-01

    The possibility is studied for obtaining intense cold atomic beams by using the Renyi entropy to optimise the laser cooling process. It is shown in the case of a Gaussian velocity distribution of atoms, the Renyi entropy coincides with the density of particles in the phase space. The optimisation procedure for cooling atoms by resonance optical radiation is described, which is based on the thermodynamic law of increasing the Renyi entropy in time. Our method is compared with the known methods for increasing the laser cooling efficiency such as the tuning of a laser frequency in time and a change of the atomic transition frequency in an inhomogeneous transverse field of a magnetic solenoid. (laser cooling)

  13. Eficiência/desempenho hospitalar e resultados da gestão de recursos humanos – uma aproximação possível?

    Directory of Open Access Journals (Sweden)

    Júnia Marçal Rodrigues

    2016-04-01

    Full Text Available O principal objetivo dessa discussão teórica foi verificar em que medida a Gestão de Recursos Humanos (GRH contribui para o desempenho de hospitais na perspectiva da eficiência. A revisão de literatura tratou da inserção da eficiência como uma das possibilidades de avaliar o desempenho hospitalar. E também das prerrogativas para mensurar a contribuição de Recursos Humanos (RH em organizações industriais e de saúde. Considerando esses objetivos iniciais foi feito um apanhado da literatura para identificar quais são as métricas usualmente utilizadas para tecer uma aproximação entre a gestão de recursos humanos e o desempenho de instituições hospitalares. Os indicadores levantados podem servir de ponto de partida para a elaboração de iniciativas dedicadas ao monitoramento de ações de gestão de recursos humanos na saúde.

  14. Controle de estoque: um estudo sobre a eficiência da gestão de estoque numa distribuidora atacadista em Divinópolis, MG

    Directory of Open Access Journals (Sweden)

    Valdilene Gonçalves Machado Silva

    2018-01-01

    Full Text Available O objetivo deste trabalho é identificar as ferramentas mais adequadas, e como elas podem aumentar a eficiência da gestão de estoque em uma microempresa distribuidora atacadista, que atua no ramo de produtos alimentícios refrigerados em Divinópolis, MG. Realizou-se uma pesquisa descritiva com abordagem qualitativa, através de um estudo de caso. Os dados foram levantados pela observação direta da rotina de trabalho do almoxarifado da empresa, pesquisa documental e entrevista semiestruturada com o gestor de estocagem e o expedidor. Observou-se que as principais fragilidades dessa gestão são a falta de controle na quantidade de mercadorias em estoque, mercadorias deterioradas e com prazo de validade vencido, perda de vendas por falta de mercadorias e mercadorias sem a atenção necessária. Portanto, concluiu-se que a utilização de ferramentas como a curva ABC, inventário físico, Peps e o estabelecimento de nível de atendimento à demanda contribuirão para o aumento da eficiência da gestão de estoque.

  15. Corrupção e Crescimento: os impactos da corrupção ponderados pelos diferentes graus de eficiência entre as firmas

    Directory of Open Access Journals (Sweden)

    Leonardo Andrade Rocha

    Full Text Available Resumo O presente estudo analisou os impactos da corrupção no crescimento das firmas conforme diferentes 'graus' de eficiência. Usando uma técnica não paramétrica de escores de eficiência, foi estimado um modelo de regressão linear interagindo os diferentes escores com um índice de corrupção. Os resultados apontam que a corrupção apresenta impactos negativos nas firmas com baixa performance, ao contrário das firmas com alta performance. Neste sentido, a posição da firma eficiente conforme a fronteira quantílica condiciona significativamente o custo da corrupção, sugerindo um efeito heterogêneo que não é precisamente capturado pelas técnicas tradicionais. Tais resultados corroboram com importantes estudos destacando Batra, Kaufmann e Stone (2003, Wang e You (2012 e Jiang e Nie (2014.

  16. Atomic force microscopy. A new method for atom identification and manipulation

    International Nuclear Information System (INIS)

    Abe, Masayuki; Sugimoto, Yoshiaki; Morita, Seizo

    2007-01-01

    Frequency modulation atomic force microscopy (FM-AFM) is a scanning probe technique that detects the interaction forces between the outermost atom of a sharp tip and the atoms at a surface to image the sample surface. It is expected that the FM-AFM can cover the research field which scanning tunneling microscopy does not provide. In this article, we would introduce FM-AFM experiments applied to site-specific force measurements and atom manipulation, including how to solve the problems to achieve precise FM-AFM measurements. (author)

  17. Three-atom clusters

    International Nuclear Information System (INIS)

    Pen'kov, F.M.

    1998-01-01

    The Born-Oppenheimer approximation is used to obtain an equation for the effective interaction in three atoms bound by a single electron. For low binding energies in an 'electron + atom' pair, long-range forces arise between the atoms, leading to bound states when the size of the three-atom cluster is a few tens of angstrom. A system made of alkali-metal atoms is considered as an example

  18. Stable atomic hydrogen: Polarized atomic beam source

    International Nuclear Information System (INIS)

    Niinikoski, T.O.; Penttilae, S.; Rieubland, J.M.; Rijllart, A.

    1984-01-01

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

  19. Análise da eqüidade e da eficiência dos estados no contexto do federalismo fiscal brasileiro

    Directory of Open Access Journals (Sweden)

    Celso Vila Nova de Souza Júnior

    2006-12-01

    Full Text Available O artigo avalia em que medida o Fundo de Participação dos Estados (FPE atende aos objetivos redistributivos traçados pela Constituição Federal bem como o seu impacto sobre a eficiência da gestão pública. Emprega-se a Análise de Componentes Principais (ACP e a Análise de Envoltória de Dados (DEA para estimar a eficiência relativa dos 27 Estados brasileiros em três etapas. Na primeira, constrói-se uma fronteira de melhor disponibilidade de serviços para avaliar a eqüidade distributiva entre os Estados. Em seguida, uma função custo é usada para se obter um índice de eficiência dos gastos públicos. Na terceira etapa estima-se uma fronteira que descreve a eficiência arrecadatória. Mediante a integração dessas três análises obtém-se o nível ótimo de transferências do FPE. Os resultados mostram que a região Sul apresentou a melhor disponibilidade de serviços e a maior eficiência no uso dos recursos. No extremo oposto encontra-se o Nordeste, onde há fortes carências e também grande desperdício. Quanto ao esforço de arrecadação, não se evidenciaram perdas tributárias acentuadas. O estudo conclui que todos os Estados necessitam de complementação de verbas, mas constata distorções presentes no atual critério.This article evaluates whether the State Participation Fund (FPE achieves the redistributive goals established by the Federal Constitution, as well as its impact on public administration efficiency. We use Principal Component Analysis (PCA and Data Envelopment Analysis (DEA in order to estimate the relative efficiency of the 27 Brazilian states in three steps. First, we build an optimal public service supply frontier in order to evaluate the distributive equity among states. Then, we use a cost function to obtain a public expenditure efficiency index. Third, we estimate a frontier that describes tax revenue efficiency. Integrating these three analyses, we obtain the optimal level of transfers from the

  20. Dynamics of moving interacting atoms in a laser radiation field and optical size resonances

    International Nuclear Information System (INIS)

    Gadomskii, O.N.; Glukhov, A.G.

    2005-01-01

    The forces acting on interacting moving atoms exposed to resonant laser radiation are calculated. It is shown that the forces acting on the atoms include the radiation pressure forces as well as the external and internal bias forces. The dependences of the forces on the atomic spacing, polarization, and laser radiation frequency are given. It is found that the internal bias force associated with the interaction of atomic dipoles via the reemitted field may play an important role in the dynamics of dense atomic ensembles in a light field. It is shown that optical size resonances appear in the system of interacting atoms at frequencies differing substantially from transition frequencies in the spectrum of atoms. It is noted that optical size resonances as well as the Doppler frequency shift in the spectrum of interacting atoms play a significant role in the processes of laser-radiation-controlled motion of the atoms

  1. On the dynamic polarizability of atoms

    International Nuclear Information System (INIS)

    Nuroh, K.; Zaremba, E.

    1989-04-01

    The positive frequency dependent polarizability of atoms is discussed in terms of the particle-hole polarization propagator. It is considered in the simplest approximation defined by the Bethe-Salpeter equation which includes a subset of particle-hole interactions to all orders in the Coulomb potential. Its solution is used to show the relationship between different formulations of atomic photoabsorption via the effective dipole matrix element (Fermi's 'golden rule'), the TDLDA and the reaction matrix. (author). 21 refs, 7 figs

  2. Influence of modulation frequency in rubidium cell frequency standards

    Science.gov (United States)

    Audoin, C.; Viennet, J.; Cyr, N.; Vanier, J.

    1983-01-01

    The error signal which is used to control the frequency of the quartz crystal oscillator of a passive rubidium cell frequency standard is considered. The value of the slope of this signal, for an interrogation frequency close to the atomic transition frequency is calculated and measured for various phase (or frequency) modulation waveforms, and for several values of the modulation frequency. A theoretical analysis is made using a model which applies to a system in which the optical pumping rate, the relaxation rates and the RF field are homogeneous. Results are given for sine-wave phase modulation, square-wave frequency modulation and square-wave phase modulation. The influence of the modulation frequency on the slope of the error signal is specified. It is shown that the modulation frequency can be chosen as large as twice the non-saturated full-width at half-maximum without a drastic loss of the sensitivity to an offset of the interrogation frequency from center line, provided that the power saturation factor and the amplitude of modulation are properly adjusted.

  3. Pharao: study of an atomic clock using laser-cooled atoms and realization of a prototype

    International Nuclear Information System (INIS)

    Lemonde, P.

    1997-01-01

    Thermal jets and atomic fountains are two different principles on which atomic clocks are based. In atomic fountains the velocity of atoms can be reduced to a few cm/s so the classical limitations of thermal jets such as phase shift between two Ramsey impulses, second order Doppler effect become negligible. The new limitations set by atomic fountain clocks are now collisions between cold atoms and the radiation emitted by the black body. Weightlessness leads to a different running of the atomic clock and can imply an enhancement of its performances. In micro-gravity an interatomic interaction time of several seconds can be reached. The application of such atomic clocks can go beyond time or frequency metrology. This work is dedicated to the development of a spatial atomic clock to fully use the extremely low velocity of laser-cooled atoms and to quantify what can be expected of weightlessness. This study has involved the realization of a prototype and its testing in a zero-g plane. The experimental results are presented and it is highlighted that an accuracy and a one-day stability of 10 -16 are within reach with an optimized version of this atomic clock. (A.C.)

  4. Hydrogen atom kinetics in capacitively coupled plasmas

    Science.gov (United States)

    Nunomura, Shota; Katayama, Hirotaka; Yoshida, Isao

    2017-05-01

    Hydrogen (H) atom kinetics has been investigated in capacitively coupled very high frequency (VHF) discharges at powers of 16-780 mW cm-2 and H2 gas pressures of 0.1-2 Torr. The H atom density has been measured using vacuum ultra violet absorption spectroscopy (VUVAS) with a micro-discharge hollow cathode lamp as a VUV light source. The measurements have been performed in two different electrode configurations of discharges: conventional parallel-plate diode and triode with an intermediate mesh electrode. We find that in the triode configuration, the H atom density is strongly reduced across the mesh electrode. The H atom density varies from ˜1012 cm-3 to ˜1010 cm-3 by crossing the mesh with 0.2 mm in thickness and 36% in aperture ratio. The fluid model simulations for VHF discharge plasmas have been performed to study the H atom generation, diffusion and recombination kinetics. The simulations suggest that H atoms are generated in the bulk plasma, by the electron impact dissociation (e + H2 \\to e + 2H) and the ion-molecule reaction (H2 + + H2 \\to {{{H}}}3+ + H). The diffusion of H atoms is strongly limited by a mesh electrode, and thus the mesh geometry influences the spatial distribution of the H atoms. The loss of H atoms is dominated by the surface recombination.

  5. Optical atomic phase reference and timing.

    Science.gov (United States)

    Hollberg, L; Cornell, E H; Abdelrahmann, A

    2017-08-06

    Atomic clocks based on laser-cooled atoms have made tremendous advances in both accuracy and stability. However, advanced clocks have not found their way into widespread use because there has been little need for such high performance in real-world/commercial applications. The drive in the commercial world favours smaller, lower-power, more robust compact atomic clocks that function well in real-world non-laboratory environments. Although the high-performance atomic frequency references are useful to test Einstein's special relativity more precisely, there are not compelling scientific arguments to expect a breakdown in special relativity. On the other hand, the dynamics of gravity, evidenced by the recent spectacular results in experimental detection of gravity waves by the LIGO Scientific Collaboration, shows dramatically that there is new physics to be seen and understood in space-time science. Those systems require strain measurements at less than or equal to 10 -20 As we discuss here, cold atom optical frequency references are still many orders of magnitude away from the frequency stability that should be achievable with narrow-linewidth quantum transitions and large numbers of very cold atoms, and they may be able to achieve levels of phase stability, Δ Φ / Φ total  ≤ 10 -20 , that could make an important impact in gravity wave science.This article is part of the themed issue 'Quantum technology for the 21st century'. © 2017 The Author(s).

  6. Optical atomic phase reference and timing

    Science.gov (United States)

    Hollberg, L.; Cornell, E. H.; Abdelrahmann, A.

    2017-06-01

    Atomic clocks based on laser-cooled atoms have made tremendous advances in both accuracy and stability. However, advanced clocks have not found their way into widespread use because there has been little need for such high performance in real-world/commercial applications. The drive in the commercial world favours smaller, lower-power, more robust compact atomic clocks that function well in real-world non-laboratory environments. Although the high-performance atomic frequency references are useful to test Einstein's special relativity more precisely, there are not compelling scientific arguments to expect a breakdown in special relativity. On the other hand, the dynamics of gravity, evidenced by the recent spectacular results in experimental detection of gravity waves by the LIGO Scientific Collaboration, shows dramatically that there is new physics to be seen and understood in space-time science. Those systems require strain measurements at less than or equal to 10-20. As we discuss here, cold atom optical frequency references are still many orders of magnitude away from the frequency stability that should be achievable with narrow-linewidth quantum transitions and large numbers of very cold atoms, and they may be able to achieve levels of phase stability, ΔΦ/Φtotal ≤ 10-20, that could make an important impact in gravity wave science. This article is part of the themed issue 'Quantum technology for the 21st century'.

  7. Optical ferris wheel for ultracold atoms

    Science.gov (United States)

    Franke-Arnold, S.; Leach, J.; Padgett, M. J.; Lembessis, V. E.; Ellinas, D.; Wright, A. J.; Girkin, J. M.; Ohberg, P.; Arnold, A. S.

    2007-07-01

    We propose a versatile optical ring lattice suitable for trapping cold and quantum degenerate atomic samples. We demonstrate the realisation of intensity patterns from pairs of Laguerre-Gauss (exp(iℓө) modes with different ℓ indices. These patterns can be rotated by introducing a frequency shift between the modes. We can generate bright ring lattices for trapping atoms in red-detuned light, and dark ring lattices suitable for trapping atoms with minimal heating in the optical vortices of blue-detuned light. The lattice sites can be joined to form a uniform ring trap, making it ideal for studying persistent currents and the Mott insulator transition in a ring geometry.

  8. 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...

  9. 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...

  10. 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.

  11. Progress in atomic spectroscopy

    International Nuclear Information System (INIS)

    Beyer, H.J.; Kleinpoppen, H.

    1984-01-01

    This book presents reviews by leading experts in the field covering areas of research at the forefront of atomic spectroscopy. Topics considered include the k ordering of atomic structure, multiconfiguration Hartree-Fock calculations for complex atoms, new methods in high-resolution laser spectroscopy, resonance ionization spectroscopy (inert atom detection), trapped ion spectroscopy, high-magnetic-field atomic physics, the effects of magnetic and electric fields on highly excited atoms, x rays from superheavy collision systems, recoil ion spectroscopy with heavy ions, investigations of superheavy quasi-atoms via spectroscopy of electron rays and positrons, impact ionization by fast projectiles, and amplitudes and state parameters from ion- and atom-atom excitation processes

  12. Frequency spirals

    International Nuclear Information System (INIS)

    Ottino-Löffler, Bertrand; Strogatz, Steven H.

    2016-01-01

    We study the dynamics of coupled phase oscillators on a two-dimensional Kuramoto lattice with periodic boundary conditions. For coupling strengths just below the transition to global phase-locking, we find localized spatiotemporal patterns that we call “frequency spirals.” These patterns cannot be seen under time averaging; they become visible only when we examine the spatial variation of the oscillators' instantaneous frequencies, where they manifest themselves as two-armed rotating spirals. In the more familiar phase representation, they appear as wobbly periodic patterns surrounding a phase vortex. Unlike the stationary phase vortices seen in magnetic spin systems, or the rotating spiral waves seen in reaction-diffusion systems, frequency spirals librate: the phases of the oscillators surrounding the central vortex move forward and then backward, executing a periodic motion with zero winding number. We construct the simplest frequency spiral and characterize its properties using analytical and numerical methods. Simulations show that frequency spirals in large lattices behave much like this simple prototype.

  13. Frequency spirals

    Energy Technology Data Exchange (ETDEWEB)

    Ottino-Löffler, Bertrand; Strogatz, Steven H., E-mail: strogatz@cornell.edu [Center for Applied Mathematics, Cornell University, Ithaca, New York 14853 (United States)

    2016-09-15

    We study the dynamics of coupled phase oscillators on a two-dimensional Kuramoto lattice with periodic boundary conditions. For coupling strengths just below the transition to global phase-locking, we find localized spatiotemporal patterns that we call “frequency spirals.” These patterns cannot be seen under time averaging; they become visible only when we examine the spatial variation of the oscillators' instantaneous frequencies, where they manifest themselves as two-armed rotating spirals. In the more familiar phase representation, they appear as wobbly periodic patterns surrounding a phase vortex. Unlike the stationary phase vortices seen in magnetic spin systems, or the rotating spiral waves seen in reaction-diffusion systems, frequency spirals librate: the phases of the oscillators surrounding the central vortex move forward and then backward, executing a periodic motion with zero winding number. We construct the simplest frequency spiral and characterize its properties using analytical and numerical methods. Simulations show that frequency spirals in large lattices behave much like this simple prototype.

  14. Eficiência do metalaxyl no controle da requeima do tomateiro Efficiency of Metalaxyl to control tomato late blight

    Directory of Open Access Journals (Sweden)

    Celson Rodrigues

    2000-03-01

    Full Text Available Foi avaliada a eficiência das dosagens de 1; 2,5 e 5 g/cova do fungicida Ridomil 50 gr (metalaxyl 50 g/kg, em aplicação única no solo, comparada com a dosagem de 400 g/100 litros de água do Fólio (metalaxyl + clorotalonil, 80 + 400 g/kg e do Ridomil Mancozeb br (metalaxyl + mancozeb, 80 + 640 g/kg, em dez pulverizações, para o controle da requeima do tomateiro cv. Santa Clara. O delineamento experimental foi de blocos ao acaso com seis tratamentos e quatro repetições. A percentagem de área foliar lesionada pela requeima foi de 2,75% no tratamento com Folio, 7,25% com Ridomil Mancozeb br; 18,25; 18,50 e 24,25% com as dosagens crescentes do Ridomil 50 gr, e 34,25% com a ausência de tratamento com fungicidas (testemunha. A produção de frutos comercialmente aceitáveis por dez plantas de tomateiro, avaliadas em cada parcela experimental, durante quatro semanas a partir de 90 dias do transplantio do tomateiro foi de 10,26 kg para o tratamento com o Folio, 9,10 kg para o Ridomil Mancozeb br, 2,07 kg; 1,86 e 1,74 kg para as dosagens crescentes do Ridomil 50 gr, enquanto para a testemunha foi de 1,58 kg. Estes resultados demonstraram a superioridade dos fungicidas Folio e Ridomil Mancozeb br em relação ao Ridomil 50 gr, para o controle da requeima do tomateiro, nas condições experimentais utilizadas.An experiment was conducted to study the efficiency of the dosages of 1; 2.5 and 5 g/plant, of the fungicide ridomil 50 gr (metalaxyl, 50 g/kg, in only one application in the soil, compared with the dosage of 400 g/100 liters of water, of the folio (metalaxyl + chlorothalonil, 80 + 400 g/kg and of the ridomil mancozeb br (metalaxyl + mancozeb, 80 + 640 g/kg, in ten pulverizations for the control of the late blight of the tomato cv. Santa Clara. The experiments were set up in a complete randomized design, with six treatments and four replications. The percentage of the damaged foliage area caused by late blight was of 2.75% in the treatment

  15. Atomic Fisher information versus atomic number

    International Nuclear Information System (INIS)

    Nagy, A.; Sen, K.D.

    2006-01-01

    It is shown that the Thomas-Fermi Fisher information is negative. A slightly more sophisticated model proposed by Gaspar provides a qualitatively correct expression for the Fisher information: Gaspar's Fisher information is proportional to the two-third power of the atomic number. Accurate numerical calculations show an almost linear dependence on the atomic number

  16. Mass defect effects in atomic clocks

    Science.gov (United States)

    Yudin, Valeriy; Taichenachev, Alexey

    2018-03-01

    We consider some implications of the mass defect on the frequency of atomic transitions. We have found that some well-known frequency shifts (the gravitational shift and motion-induced shifts such as quadratic Doppler and micromotion shifts) can be interpreted as consequences of the mass defect in quantum atomic physics, i.e. without the need for the concept of time dilation used in special and general relativity theories. Moreover, we show that the inclusion of the mass defect leads to previously unknown shifts for clocks based on trapped ions.

  17. Low frequency radioastronomy

    International Nuclear Information System (INIS)

    Zarka, Philippe; Cecconi, Baptiste; Tagger, Michel; Torchinsky, Steve; Picard, Philippe; Pezzani, Jacques; Cognard, Ismael; Boone, Frederic; Woan, Graham; Weber, Rodolphe; Gousset, Thierry; Lautridou, Pascal; Dallier, Richard

    2011-07-01

    Low frequency radioastronomy deals with the direct detection (below 100 MHz) and heterodyne detection (up to few GHz) of electromagnetic waves (phase and amplitude) followed by a time or spectral analysis. The 30. Goutelas school covered several aspects of radioastronomy involving various aspects of physics: non-thermal phenomena in plasmas and physics of magnetized plasmas, atomic and molecular physics, and particle physics. These proceedings comprise 17 lectures dealing with: 1 - Low-Frequency Radioastronomy Basics (P. Zarka); 2 - Radioastronomy Historical Highlights (S. A. Torchinsky); 3 - Antennas (P. Picard, J. Pezzani); 4 - Receptors (P. Picard, J. Pezzani); 5 - Pulsars chronometry: metrology in radioastronomy (I. Cognard); 6 - Interferometry as imaging technique (F. Boone); 7 - Radio propagation and scintillation (G. Woan); 8 - Square Kilometer Array (S. A. Torchinsky); 9 - Techniques against radio-electrical interferences in low-frequency radioastronomy (R. Weber); 10 - Introduction to poly-phase filtering (R. Weber); 11 - Three decades of Jupiter's radio-emission studies: from the Nancay deca-meter network to LOFAR (P. Zarka); 12 - Atmospheric showers and their radio counterpart (T. Gousset); 13 - From cosmic rays radio-detection to pulse radioastronomy (P. Lautridou, R. Dallier); 14 - The CODALEMA project (R. Dallier, P. Lautridou); 15 - Space-based radio measurements: Gonio-polarimetry (B. Cecconi); 16 - Radio astronomy from space (G. Woan); 17 - LOFAR: the Low Frequency Array and the French FLOW consortium (M. Tagger, P. Zarka)

  18. High-precision atom localization via controllable spontaneous emission in a cycle-configuration atomic system.

    Science.gov (United States)

    Ding, Chunling; Li, Jiahua; Yu, Rong; Hao, Xiangying; Wu, Ying

    2012-03-26

    A scheme for realizing two-dimensional (2D) atom localization is proposed based on controllable spontaneous emission in a coherently driven cycle-configuration atomic system. As the spatial-position-dependent atom-field interaction, the frequency of the spontaneously emitted photon carries the information about the position of the atom. Therefore, by detecting the emitted photon one could obtain the position information available, and then we demonstrate high-precision and high-resolution 2D atom localization induced by the quantum interference between the multiple spontaneous decay channels. Moreover, we can achieve 100% probability of finding the atom at an expected position by choosing appropriate system parameters under certain conditions.

  19. Atomic-fluorescence spectrophotometry

    International Nuclear Information System (INIS)

    Bakhturova, N.F.; Yudelevich, I.G.

    1975-01-01

    Atomic-fluorescence spectrophotometry, a comparatively new method for the analysis of trace quantities, has developed rapidly in the past ten years. Theoretical and experimental studies by many workers have shown that atomic-fluorescence spectrophotometry (AFS) is capable of achieving a better limit than atomic absorption for a large number of elements. The present review examines briefly the principles of atomic-fluorescence spectrophotometry and the types of fluorescent transition. The excitation sources, flame and nonflame atomizers, used in AFS are described. The limits of detection achieved up to the present, using flame and nonflame methods of atomization are given

  20. Hg(+) Frequency Standards

    Science.gov (United States)

    Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    2000-01-01

    In this paper we review the development of Hg(+) microwave frequency standards for use in high reliability and continuous operation applications. In recent work we have demonstrated short-term frequency stability of 3 x 10(exp -14)/nu(sub tau) when a cryogenic oscillator of stability 2-3 x 10(exp 15) was used a the local oscillator. The trapped ion frequency standard employs a Hg-202 discharge lamp to optically pump the trapped Hg(+)-199 clock ions and a helium buffer gas to cool the ions to near room temperature. We describe a small Hg(+) ion trap based frequency standard with an extended linear ion trap (LITE) architecture which separates the optical state selection region from the clock resonance region. This separation allows the use of novel trap configurations in the resonance region since no optical pumping is carried out there. A method for measuring the size of an ion cloud inside a linear trap with a 12-rod trap is currently being investigated. At approx. 10(exp -12), the 2nd order Doppler shift for trapped mercury ion frequency standards is one of the largest frequency offsets and its measurement to the 1% level would represent an advance in insuring the very long-term stability of these standards to the 10(exp -14) or better level. Finally, we describe atomic clock comparison experiments that can probe for a time variation of the fine structure constant, alpha = e(exp 2)/2(pi)hc, at the level of 10(exp -20)/year as predicted in some Grand Unified String Theories.

  1. Accessing photon number via an atomic time interval

    International Nuclear Information System (INIS)

    Camparo, J.C.; Coffer, J.G.

    2002-01-01

    We show that Rabi resonances can be used to assess field strength in terms of time at the atomic level. Rabi resonances are enhancements in the amplitude of atomic population oscillations when the Rabi frequency, Ω, 'matches' a field-modulation frequency, ω m . We demonstrate that Ω=2κω m and find that κ=1.03±0.05. Since Ω is defined by field strength (i.e., photon number) through atomic constants, and ω m may be referenced to an atomic clock, our work shows that Rabi resonances provide a connection between time and photon number

  2. Atom Wavelike Nature Solved Mathematically

    Science.gov (United States)

    Sven, Charles

    2010-03-01

    Like N/S poles of a magnet the strong force field surrounding, confining the nucleus exerts an equal force [noted by this author] driving electrons away from the attraction of positively charged protons force fields in nucleus -- the mechanics for wavelike nature of electron. Powerful forces corral closely packed protons within atomic nucleus with a force that is at least a million times stronger than proton's electrical attraction that binds electrons. This then accounts for the ease of electron manipulation in that electron is already pushed away by the very strong atomic N/S force field; allowing electrons to drive photons when I strike a match. Ageless atom's electron requirements, used to drive light/photons or atom bomb, without batteries, must be supplied from a huge, external, super high frequency, super-cooled source, undetected by current technology, one that could exist 14+ billion years without degradation -- filling a limitless space prior to Big Bang. Using only replicable physics, I show how our Universe emanated from that event.

  3. Laser control of atomic beam motion and applications

    International Nuclear Information System (INIS)

    Balykin, V.I.; Letokhov, V.S.

    1987-01-01

    The authors present the results of an experimental investigation of the control of atomic beam motion by the light pressure of laser radiation. Collimation, focusing and reflection of the atomic beam are considered. Collimation of the atomic beam is achieved by the interaction of laser radiation with atoms, when the light pressure force depends only on the atom's velocity. A similar regime of atomic beam interaction with radiation was performed with transversal irradiation of a beam by the axis-symmetrical field. The axis-symmetrical field was formed by laser radiation reflected from the conical mirror surface of a reflecting axicon. The axis of the atomic beam coincided with that of the axicon. The collimation regime was reached under negative detuning of the laser radiation frequency from the atomic transition frequency by a value equal to several homogeneous widths. With positive detuning by the same value the regime of beam decollimation was observed. The density of atoms on the beam axis was changed by 10 3 times, when the collimation regime was replaced by that of decollimation. Focusing of the atomic beam was achieved by light pressure dependent on the atomic coordinate. Focusing was performed within the field configuration formed by divergent laser Gaussian beams propagating in the direction +- X, +- Y of a Cartesian coordinate system. Waists of the laser beams were an equal distance from the atomic beam axis. With an atomic beam propagating along the z axis, expressions for local distance and a formula for the laser lens were obtained. Focusing of the atomic beam was experimentally accomplished, and the image of the atomic beam was received. In this work they also investigated reflection of the atomic beam by laser radiation. The possibility of creating the optics of a neutral atomic beam is shown

  4. Agrotóxicos: eficiência econômica e injustiça socioambiental Pesticides: economic efficiency and social and environmental injustice

    Directory of Open Access Journals (Sweden)

    Marcelo Motta Veiga

    2007-03-01

    Full Text Available Este estudo analisou a relação inversa entre eficiência econômica e justiça socioambiental na utilização de agrotóxicos. A utilização de agrotóxicos tenderia a maximizar a eficiência econômica através de ganhos de produtividade; no entanto, poderia agravar a injustiça socioambiental. Inferiu-se essa relação inversa, uma vez que a eficiência econômica pela utilização de agrotóxicos estaria associada a alguma injustiça socioambiental. Este estudo analisou, ainda, o impacto de instrumentos regulatórios no controle da utilização e do manejo de agrotóxicos. Uma legislação que reduza compulsoriamente a utilização de agrotóxicos poderia agravar diversos problemas socioeconômicos, especialmente em pequenas comunidades rurais. Concluiu-se que eventuais restrições na utilização de agrotóxicos em sistemas produtivos que dependam dessas matérias-primas para sustentar sua economia poderia ser bastante prejudicial. Quanto à necessidade de intervenção estatal para regular a utilização de agrotóxicos, este estudo concluiu que a questão não deveria ser sobre a necessidade ou não de legislação, mas sim como deve ser a forma dessa intervenção.This study analyzed the inverse relationship between economic efficiency and social and environmental justice in the use of pesticides. The use of pesticides tends to improve economic efficiency by increasing agricultural productivity, however, it can also increase social and environmental injustice. This inverse relationship was inferred since the economic efficiency gained with the use of pesticides is [usually] associated with some kind of social and environmental injustice. This study also analyzed the impact of regulatory measures to control the use and handling of pesticides. Strict pesticide regulations could jeopardize agricultural competitiveness, especially in some small rural communities; therefore, the cost-benefit results of pesticides regulations could be

  5. Eficiência hidrológica de telhados verdes para a escala de loteamentos residenciais / Hydrological efficiency of green roofs for residential neighborhoods scale

    Directory of Open Access Journals (Sweden)

    José Eduardo Alamy Filho

    2016-11-01

    Full Text Available O presente trabalho teve o objetivo de estimar o comportamento de um conjunto de telhados verdes em relação à sua capacidade de inibição do escoamento superficial, utilizando a escala espacial de loteamento. A eficiência hidrológica dos telhados verdes foi avaliada em função da redução relativa do volume de escoamento superficial, comparando a situação de implantação da cobertura permeável, em todas as edificações de um loteamento, com a situação de telhado convencional impermeável. As estimativas teóricas utilizaram um modelo hidrológico, com imposição de diversos cenários de precipitação. O efeito das chuvas foi introduzido pela equação de intensidade, duração e frequência local e por distribuições temporais sintéticas. Os tipos e usos do solo foram considerados a partir do parâmetro curva-número. A metodologia proposta foi aplicada para um condomínio residencial situado na cidade de Uberlândia, Minas Gerais. Os resultados das simulações hidrológicas indicaram que a implantação de telhados verdes aponta para reduções expressivas do volume de escoamento superficial. Neste contexto, estimaram-se eficiências entre 2,02% e 55,67%. Para condições de solo inicialmente seco, que são comuns após estiagens, foi prevista uma eficiência hidrológica média de 40,35%. A despeito disto, este índice reduz-se para 10,44% em situações de saturação iminente, decorrentes de chuvas anteriores sucessivas. A despeito da sua dependência da umidade antecedente do solo, este potencial de redução do escoamento superficial é considerável. Assim, a implantação de telhados verdes contribui para atenuar as vazões de pico geradas na saída do loteamento, aliviando o sistema público de drenagem e, num contexto mais amplo, reduzindo os riscos de enchentes ribeirinhas nos fundos de vale. Palavras-chave: drenagem urbana, telhados verdes, escoamento superficial.

  6. A Single Atom Antenna

    International Nuclear Information System (INIS)

    Trinter, Florian; Williams, Joshua B; Weller, Miriam; Waitz, Markus; Pitzer, Martin; Voigtsberger, Jörg; Schober, Carl; Kastirke, Gregor; Müller, Christian; Goihl, Christoph; Burzynski, Phillip; Wiegandt, Florian; Wallauer, Robert; Kalinin, Anton; Schmidt, Lothar Ph H; Schöffler, Markus S; Jahnke, Till; Dörner, Reinhard; Chiang, Ying-Chih; Gokhberg, Kirill

    2015-01-01

    Here we demonstrate the smallest possible implementation of an antenna-receiver complex which consists of a single (helium) atom acting as the antenna and a second (neon) atom acting as a receiver. (paper)

  7. Atomic interferometers in an optical lattice

    International Nuclear Information System (INIS)

    Pelle, Bruno

    2013-01-01

    The aim of the ForCa-G project, for Casimir force and short range Gravitation, lies into the measurement of short range forces between atoms and a mirror using atomic interferometry techniques. Particularly, the Casimir-Polder force and the pursuit of short range gravitational tests in the frame of potential deviations of Newton's law are aimed. This experiment is based on the trapping of neutral atoms in a 1D vertical optical lattice, where the energy eigenvalues of the Hamiltonian describing this system is the so-called Wannier-Stark ladder of discrete energy states localized in each lattice well. This work constitutes a demonstration of principle of this project with atoms set far from the mirror. Each energy state is thus separated from the one of the adjacent well by the potential energy increment between those two wells, called the Bloch frequency ν B . Then, atomic interferometers are realized in the lattice using Raman or microwave pulses where the trapped atomic wave functions are placed, and then recombined, in a superposition of states between different energy states localized either in the same well, either in adjacent wells. This work presents the study of different kinds of atomic interferometers in this optical lattice, characterized in terms of sensibility and systematic effects on the Bloch frequency measurement. One of the studied interferometers accessed to a sensitivity on the Bloch frequency of σ δ ν B /ν B =9.0x10 -6 at 1∼s in relative, which integrates until σ δ ν B /ν B =1. 10 -7 in 2800∼s. This corresponds to a state-of-the-art measurement of the gravity acceleration g for a trapped atomic gravimeter. (author)

  8. Atom chips: mesoscopic physics with cold atoms

    International Nuclear Information System (INIS)

    Krueger, P.; Wildermuth, S.; Hofferberth, S.; Haller, E.; GAllego Garcia, D.; Schmiedmayer, J.

    2005-01-01

    Full text: Cold neutral atoms can be controlled and manipulated in microscopic potentials near surfaces of atom chips. These integrated micro-devices combine the known techniques of atom optics with the capabilities of well established micro- and nanofabrication technology. In analogy to electronic microchips and integrated fiber optics, the concept of atom chips is suitable to explore the domain of mesoscopic physics with matter waves. We use current and charge carrying structures to form complex potentials with high spatial resolution only microns from the surface. In particular, atoms can be confined to an essentially one-dimensional motion. In this talk, we will give an overview of our experiments studying the manipulation of both thermal atoms and BECs on atom chips. First experiments in the quasi one-dimensional regime will be presented. These experiments profit from strongly reduced residual disorder potentials caused by imperfections of the chip fabrication with respect to previously published experiments. This is due to our purely lithographic fabrication technique that proves to be advantageous over electroplating. We have used one dimensionally confined BECs as an ultra-sensitive probe to characterize these potentials. These smooth potentials allow us to explore various aspects of the physics of degenerate quantum gases in low dimensions. (author)

  9. Quasi-atoms

    International Nuclear Information System (INIS)

    Armbruster, P.

    1976-01-01

    The concept of a quasi-atom is discussed, and several experiments are described in which molecular or quasi-atomic transitions have been observed. X-ray spectra are shown for these experiments in which heavy ion projectiles were incident on various targets and the resultant combined system behaved as a quasi-atom. This rapidly developing field has already given new insight into atomic collision phenomena. (P.J.S.)

  10. Effects of mass defect in atomic clocks

    Science.gov (United States)

    Taichenachev, A. V.; Yudin, V. I.

    2018-01-01

    We consider some implications of the mass defect on the frequency of atomic transitions. We have found that some well-known frequency shifts (such as gravitational and quadratic Doppler shifts) can be interpreted as consequences of the mass defect, i.e., without the need for the concept of time dilation used in special and general relativity theories. Moreover, we show that the inclusion of the mass defect leads to previously unknown shifts for clocks based on trapped ions..

  11. Atomic Energy Control Act

    International Nuclear Information System (INIS)

    1970-01-01

    This act provides for the establishment of the Atomic Energy Control Board. The board is responsible for the control and supervision of the development, application and use of atomic energy. The board is also considered necessary to enable Canada to participate effectively in measures of international control of atomic energy

  12. 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.

  13. Significância de efeitos técnicos na eficiência de produção da pesquisa agropecuária

    Directory of Open Access Journals (Sweden)

    Geraldo da Silva e Souza

    2006-03-01

    Full Text Available Neste artigo utilizam-se modelos estatísticos censurados e truncados na avaliação de efeitos técnicos que potencialmente afetam a fronteira de produção dos centros de pesquisa da Embrapa (Empresa Brasileira de Pesquisa Agropecuária. Especificamente estuda-se a significância dos fatores nível da geração fundos para pesquisa externamente ao Tesouro Nacional, ações de parceria, qualidade técnica dos projetos de pesquisa, satisfação dos clientes, mudança administrativa, tipo e tamanho, na eficiência técnica de produção dos centros de pesquisa. As medidas de eficiência técnica são calculadas com base na Análise de Envelopamento de Dados (DEA e na Análise de Fronteiras Estocásticas de Produção. Conclui-se que as medidas de eficiência DEA são mais informativas para a avaliação dos efeitos técnicos e que a geração de renda, as ações de parceria, a qualidade técnica dos projetos e o tamanho são fatores significantes. A análise estatística que conduz a esses resultados ajusta, às medidas de eficiência DEA, um modelo do tipo Tobit definido por uma distribuição na família gama. A análise Tobit é consistente com o ajuste de uma distribuição normal truncada aos resíduos obtidos de uma função de produção DEA.This article uses censored and truncated statistical models to assess technical effects potentially affecting the production frontier of Embrapa's (Empresa Brasileira de Pesquisa Agropecuária research centers. Specifically the article assesses the significance of the factors level of research funds generated externally to the National Treasury, actions of partnership, technical quality of research projects, client satisfaction, change in administration, type and size on the measurement of technical efficiency of the research centers. Efficiency measures are computed both using Data Envelopment Analysis (DEA and Stochastic Frontier methods. It is concluded that the DEA efficiency measurements provide

  14. Eficiência Técnica: Comparação entre Pequenos e Grandes Propriedades Agropecuárias: Mato Grosso

    Directory of Open Access Journals (Sweden)

    Benedito Dias Pereira

    2011-04-01

    Full Text Available Neste artigo, com base em dados do Censo Agropecuário (IBGE de 1996, recorrência à regressão múltipla, compara-se a eficiência técnica entre pequenas e grandes propriedades agropecuárias do Estado de Mato Grosso. Os resultados mostram que as pequenas propriedades, em geral, não obstante estarem sendo preteridas pelas políticas agrícolas governamentais, são mais eficientes que as grandes. Esses resultados indicam que as pequenas propriedades. se se deseja otimizar o nível de emprego e de renda da economia mato-grossense devem ser os alvos preferenciais das políticas agrícolas.

  15. Forma urbana e eficiência energética em edifícios habitacionais: análiseexploratória

    OpenAIRE

    Magalhães, Sérgio; Marques, Teresa Sá

    2014-01-01

    consumo de energia tem vindo a aumentar nas últimas décadas, entrando definitivamente nas preocupações da agenda ambiental global. O debate em torno desta temática acentuou-se após a criação do Protocolo de Quioto, através do qual os países aderentes se propõem a reduzir as emissões de gases poluentes para a atmosfera. Os consumos associados aos edifícios (residenciais e de serviços) encontram-se na ordem do dia, pois é fundamental obter uma maior sustentabilidade e eficiência energética dos ...

  16. Construção de indicadores de eficiência hídrica urbana: desafio para a gestão ambiental urbana

    Directory of Open Access Journals (Sweden)

    Liza Maria Souza de Andrade

    2007-12-01

    sanitário, limpeza urbana, gestão de resíduos sólidos, uso do solo e legislação ambiental – que possam tangenciar os diferentes tipos de zoneamento de forma sistêmica por meio de um estudo dos princípios da gestão ecológica do ciclo da água e dos critérios ambientais adotados para a implantação de futuros Planos Diretores de Drenagem urbana – PDDUs para a construção de indicadores de sustentabilidade intra-urbana de eficiência hídrica. (esse período está bastante extenso e um pouco confuso. Vou pensar em algo para ele.

  17. Relação entre eficiência mecânica e competência motora no padrão fundamental de movimento arremessar

    OpenAIRE

    Débora Alonso de Lima

    2009-01-01

    O propósito deste estudo foi verificar a relação entre os níveis de eficiência mecânica e os níveis de competência motora na tarefa arremessar em crianças escolares de 6 e 7 anos de idade. Compreendendo a importância da fase dos movimentos fundamentais para o desenvolvimento motor da criança e o papel de destaque que esta fase representa nos modelos de sequência de desenvolvimento motor, a questão norteadora deste trabalho foi entender se o padrão maduro de movimento abordado pelo ponto de vi...

  18. Modelo de sistema integrado de gestão em eficiência energética e segurança e saúde no trabalho

    OpenAIRE

    Ferreira, Swylmar dos Santos

    2011-01-01

    O presente trabalho apresenta como proposta um modelo de sistema integrado de gestão em eficiência energética e segurança e saúde no trabalho, que permite otimizar os recursos humanos, materiais, financeiros e os seus próprios custos com a implantação, além de diminuir ou eliminar os riscos elétricos e racionalizar o consumo de energia elétrica no ambiente trabalho. Obteve-se como resultados a elaboração do modelo de SGEST e sua implantação na organização, a avaliação econômica da eficientiza...

  19. Two-dimensional sub-half-wavelength atom localization via controlled spontaneous emission.

    Science.gov (United States)

    Wan, Ren-Gang; Zhang, Tong-Yi

    2011-12-05

    We propose a scheme for two-dimensional (2D) atom localization based on the controlled spontaneous emission, in which the atom interacts with two orthogonal standing-wave fields. Due to the spatially dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the resulting spontaneously emission spectrum. The phase sensitive property of the atomic system leads to quenching of the spontaneous emission in some regions of the standing-waves, which significantly reduces the uncertainty in the position measurement of the atom. We find that the frequency measurement of the emitted light localizes the atom in half-wavelength domain. Especially the probability of finding the atom at a particular position can reach 100% when a photon with certain frequency is detected. By increasing the Rabi frequencies of the driving fields, such 2D sub-half-wavelength atom localization can acquire high spatial resolution.

  20. Eficiência no uso de fósforo de variedades de arroz cultivadas em solos de várzea irrigada

    Directory of Open Access Journals (Sweden)

    Eliane Aparecida Rotili

    2010-06-01

    Full Text Available A cultura do arroz destaca-se como uma das mais importantes do mundo, por apresentar facilidade de adaptação a condições edafoclimáticas distintas. Cultivado e consumido em todos continentes, o arroz destaca-se pela produção e área de cultivo, desempenhando papel estratégico tanto em nível econômico quanto social. No Brasil, a maior parcela da produção de arroz é proveniente do ecossistema de várzea. Este trabalho objetivou estudar a eficiência e resposta ao uso de fósforo de variedades de arroz (Oryza sativa L., em várzea irrigada, no Sudoeste do Estado de Tocantins. Os tratamentos envolveram oito variedades comerciais de arroz (BRS-Jaçanã, Best-2000, BRS-Guará, BRS-Alvorada, BRA-01381, AN-Cambará, BRS 7-Taim e EPAGRI-109, que foram cultivadas em dois ambientes distintos. Para simular ambientes com baixo e alto níveis de fósforo, foram utilizadas as doses de 20 e 120 kg ha-1 de P2O5, respectivamente. O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições. Por meio da produtividade de grãos, as variedades foram classificadas quanto à eficiência no uso e resposta à aplicação de fósforo. Demonstrou-se que apenas a variedade BRS-Alvorada é eficiente quanto ao uso de fósforo e responsiva a sua aplicação.

  1. Eficiência energética de tratores agrícolas fabricados no Brasil Energy efficiency of Brazilian agricultural tractors

    Directory of Open Access Journals (Sweden)

    Gastão M. da Silveira

    2010-04-01

    Full Text Available Atualmente, cresce o interesse global na economia de combustível fóssil e na redução das emissões de gases, por motivos econômicos e ecológicos. Neste trabalho se aplicou um método para classificação de tratores agrícolas, com base na sua eficiência energética, usando-se o consumo específico (em L kWh-1 como termo de comparação. O fator energético mais importante para essa máquina é o seu motor, seguido da transmissão. O trabalho se baseia no resultado dos ensaios de tratores realizados segundo normas brasileiras, tendo como modelo o código OECD, além de ser uma classificação de modelos de tratores fabricados no País. Os tratores movidos a álcool apresentaram consumo elevado de combustível. A metodologia permite a idéia de como os tratores se comportam, no que diz respeito à eficiência energética.Nowadays there is a growing global interest in saving fossil fuel and reducing gas emissions for economical and ecological reasons. This research applied a method of classification of agricultural tractors depending on their energy efficiency, using the specific fuel consumption (in L kWh-1 as a comparison. The most important energy factor in these machines is the engine, followed by the transmission. This research is based on results of the OECD tractor test and classifies tractor models, which have been principally sold in Brazil. The tractors fueled by ethanol presented a high level of fuel consumption. The methodology allows us to understand how tractors perform in terms of energy efficiency.

  2. Atom-atom collision cascades localization

    International Nuclear Information System (INIS)

    Kirsanov, V.V.

    1980-01-01

    The presence of an impurity and thermal vibration influence on the atom-atom collision cascade development is analysed by the computer simulation method (the modificated dynamic model). It is discovered that the relatively low energetic cascades are localized with the temperature increase of an irradiated crystal. On the basis of the given effect the mechanism of splitting of the high energetic cascades into subcascades is proposed. It accounts for two factors: the primary knocked atom energy and the irradiated crystal temperature. Introduction of an impurity also localizes the cascades independently from the impurity atom mass. The cascades localization leads to intensification of the process of annealing in the cascades and reduction of the post-cascade vacancy cluster sizes. (author)

  3. An approach for the evaluation of efficiency of onion packinghouse operations Avaliação da eficiência das operações de classificação e embalagem de cebola

    Directory of Open Access Journals (Sweden)

    Andrés F.Lopes Camelo

    2003-03-01

    Full Text Available The onion is a major export crop in Argentina and obtaining consistent quality is a matter of concern to remain competitive internationally. Grading is generally done according to Mercosur standards but quality assurance programs are necessary at the packinghouse level. The objective of this study was to develop a first approach for characterizing sorting and sizing efficiency. During the 1998 season five onion packinghouses located in the Valle Bonaerense del Río Colorado (Buenos Aires Province, Argentina were randomly selected. In all of them, variables measured were: sorting table width, bulb transport and rotation speed as well as number of bulbs/sorter/hour. Before and after sorting, samples of 100 bulbs of each size category were randomly taken and closely inspected and their diameters were measured. Sizing efficiency was determined and a Chi-square test was performed to compare observed frequencies of defects with the expected ones within each category. All the studied packinghouses failed to meet the established limits for slight defects and only one of them was able to comply with the standards for basic requirements when preparing Extra class onions. Even when equipment and operational setup were different among packinghouses, the operational flux (bulbs/sorter/hour was similar for all of them. Differences in sorting performance can be attributed mainly to the sequence of operations and speed of belt conveyors. Equipment and its calibration affected sizing efficiency, with better results obtained with the diverging roller system. The proposed methodology for characterizing efficiency could be considered as a simple and useful tool for monitoring quality at onion packinghouses.A cebola é o principal produto de exportação da Argentina e a obtenção de alta qualidade é importante para manter a competitividade em nível internacional. A classificação é feita geralmente de acordo com as normas do Mercosul, porém programas de

  4. Effective oscillator strength distributions of spherically symmetric atoms for calculating polarizabilities and long-range atom–atom interactions

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jun, E-mail: phyjiang@yeah.net [Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); School of Engineering, Charles Darwin University, Darwin, Northern Territory, 0909 (Australia); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin, Northern Territory, 0909 (Australia); Cheng, Yongjun, E-mail: cyj83mail@gmail.com [School of Engineering, Charles Darwin University, Darwin, Northern Territory, 0909 (Australia); Academy of Fundamental and Interdisciplinary Science, Harbin Institute of Technology, Harbin 150080 (China); Bromley, M.W.J., E-mail: brom@physics.uq.edu.au [School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4075 (Australia)

    2015-01-15

    Effective oscillator strength distributions are systematically generated and tabulated for the alkali atoms, the alkaline-earth atoms, the alkaline-earth ions, the rare gases and some miscellaneous atoms. These effective distributions are used to compute the dipole, quadrupole and octupole static polarizabilities, and are then applied to the calculation of the dynamic polarizabilities at imaginary frequencies. These polarizabilities can be used to determine the long-range C{sub 6}, C{sub 8} and C{sub 10} atom–atom interactions for the dimers formed from any of these atoms and ions, and we present tables covering all of these combinations.

  5. Effective oscillator strength distributions of spherically symmetric atoms for calculating polarizabilities and long-range atom–atom interactions

    International Nuclear Information System (INIS)

    Jiang, Jun; Mitroy, J.; Cheng, Yongjun; Bromley, M.W.J.

    2015-01-01

    Effective oscillator strength distributions are systematically generated and tabulated for the alkali atoms, the alkaline-earth atoms, the alkaline-earth ions, the rare gases and some miscellaneous atoms. These effective distributions are used to compute the dipole, quadrupole and octupole static polarizabilities, and are then applied to the calculation of the dynamic polarizabilities at imaginary frequencies. These polarizabilities can be used to determine the long-range C 6 , C 8 and C 10 atom–atom interactions for the dimers formed from any of these atoms and ions, and we present tables covering all of these combinations

  6. On Frequency Combs in Monolithic Resonators

    Directory of Open Access Journals (Sweden)

    Savchenkov A. A.

    2016-06-01

    Full Text Available Optical frequency combs have become indispensable in astronomical measurements, biological fingerprinting, optical metrology, and radio frequency photonic signal generation. Recently demonstrated microring resonator-based Kerr frequency combs point the way towards chip scale optical frequency comb generator retaining major properties of the lab scale devices. This technique is promising for integrated miniature radiofrequency and microwave sources, atomic clocks, optical references and femtosecond pulse generators. Here we present Kerr frequency comb development in a historical perspective emphasizing its similarities and differences with other physical phenomena. We elucidate fundamental principles and describe practical implementations of Kerr comb oscillators, highlighting associated solved and unsolved problems.

  7. On Frequency Combs in Monolithic Resonators

    Science.gov (United States)

    Savchenkov, A. A.; Matsko, A. B.; Maleki, L.

    2016-06-01

    Optical frequency combs have become indispensable in astronomical measurements, biological fingerprinting, optical metrology, and radio frequency photonic signal generation. Recently demonstrated microring resonator-based Kerr frequency combs point the way towards chip scale optical frequency comb generator retaining major properties of the lab scale devices. This technique is promising for integrated miniature radiofrequency and microwave sources, atomic clocks, optical references and femtosecond pulse generators. Here we present Kerr frequency comb development in a historical perspective emphasizing its similarities and differences with other physical phenomena. We elucidate fundamental principles and describe practical implementations of Kerr comb oscillators, highlighting associated solved and unsolved problems.

  8. One Photon Can Simultaneously Excite Two or More Atoms.

    Science.gov (United States)

    Garziano, Luigi; Macrì, Vincenzo; Stassi, Roberto; Di Stefano, Omar; Nori, Franco; Savasta, Salvatore

    2016-07-22

    We consider two separate atoms interacting with a single-mode optical or microwave resonator. When the frequency of the resonator field is twice the atomic transition frequency, we show that there exists a resonant coupling between one photon and two atoms, via intermediate virtual states connected by counterrotating processes. If the resonator is prepared in its one-photon state, the photon can be jointly absorbed by the two atoms in their ground state which will both reach their excited state with a probability close to one. Like ordinary quantum Rabi oscillations, this process is coherent and reversible, so that two atoms in their excited state will undergo a downward transition jointly emitting a single cavity photon. This joint absorption and emission process can also occur with three atoms. The parameters used to investigate this process correspond to experimentally demonstrated values in circuit quantum electrodynamics systems.

  9. 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)

  10. Theory and applications of atomic and ionic polarizabilities

    International Nuclear Information System (INIS)

    Mitroy, J; Safronova, M S; Clark, Charles W

    2010-01-01

    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)

  11. Scheme of 2-dimensional atom localization for a three-level atom via quantum coherence

    OpenAIRE

    Zafar, Sajjad; Ahmed, Rizwan; Khan, M. Khalid

    2013-01-01

    We present a scheme for two-dimensional (2D) atom localization in a three-level atomic system. The scheme is based on quantum coherence via classical standing wave fields between the two excited levels. Our results show that conditional position probability is significantly phase dependent of the applied field and frequency detuning of spontaneously emitted photons. We obtain a single localization peak having probability close to unity by manipulating the control parameters. The effect of ato...

  12. Continuous magnetic trapping of laser cooled atoms

    International Nuclear Information System (INIS)

    Bagnato, V.S.; Lafyatis, G.; Martin, A.G.; Raab, E.L.; Landry, J.; Ahmad-Bitar, R.N.; Pritchard, D.E.

    1987-01-01

    The authors present here initial results of the deceleration of a thermal atomic beam from -- 1000 to -- 100 m/s. The experiment was conducted in the 1.4-m long vertical superconducting solenoid which produced the slowing field. The fluorescence of the slowed atomic beam has been studied as a function of laser frequency. Figure 2 is a 12-GHz scan showing the fluorescence at a position 150 cm from the beginning of the solenoid. The wide peak corresponds to unslowed atoms with generally the initial velocity distribution. The second, narrower, peak corresponds to slowed atoms with a velocity of -- 150 m/s. Similar spectra have been obtained for various positions along the magnetic slower and trap. These data should allow better understanding of the cooling process and will be compared to computer models

  13. Stochastic analysis/synthesis using sinusoidal atoms

    DEFF Research Database (Denmark)

    Jensen, Kristoffer

    2008-01-01

    This work proposes a method for re-synthesizing music for use in perceptual experiments regarding structural changes and in music creation. Atoms are estimated from music audio, modelled in a stochastic model, and re-synthesized from the model pa- rameters. The atoms are found by splitting...... sinusoids into short segments, and modelled into amplitude and envelope shape, frequency, time and duration. A simple model for creating envelopes with percussive, sustained or crescendo shape is presented. Single variable and joint probability density functions are created from the atom parameters and used...... to re-create sounds with the same distribution of the atoms parameters. A novel method for visualization music, the musigram, permits a better understanding of the re- synthesized sounds....

  14. Laser trapping of 21Na atoms

    International Nuclear Information System (INIS)

    Lu, Zheng-Tian.

    1994-09-01

    This thesis describes an experiment in which about four thousand radioactive 21 Na (t l/2 = 22 sec) atoms were trapped in a magneto-optical trap with laser beams. Trapped 21 Na atoms can be used as a beta source in a precision measurement of the beta-asymmetry parameter of the decay of 21 Na → 21 Ne + Β + + v e , which is a promising way to search for an anomalous right-handed current coupling in charged weak interactions. Although the number o trapped atoms that we have achieved is still about two orders of magnitude lower than what is needed to conduct a measurement of the beta-asymmetry parameter at 1% of precision level, the result of this experiment proved the feasibility of trapping short-lived radioactive atoms. In this experiment, 21 Na atoms were produced by bombarding 24 Mg with protons of 25 MeV at the 88 in. Cyclotron of Lawrence Berkeley Laboratory. A few recently developed techniques of laser manipulation of neutral atoms were applied in this experiment. The 21 Na atoms emerging from a heated oven were first transversely cooled. As a result, the on-axis atomic beam intensity was increased by a factor of 16. The atoms in the beam were then slowed down from thermal speed by applying Zeeman-tuned slowing technique, and subsequently loaded into a magneto-optical trap at the end of the slowing path. The last two chapters of this thesis present two studies on the magneto-optical trap of sodium atoms. In particular, the mechanisms of magneto-optical traps at various laser frequencies and the collisional loss mechanisms of these traps were examined

  15. Coupling ultracold atoms to a superconducting coplanar waveguide resonator

    OpenAIRE

    Hattermann, H.; Bothner, D.; Ley, L. Y.; Ferdinand, B.; Wiedmaier, D.; Sárkány, L.; Kleiner, R.; Koelle, D.; Fortágh, J.

    2017-01-01

    We demonstrate coupling of magnetically trapped ultracold $^87$Rb ground state atoms to a coherently driven superconducting coplanar resonator on an integrated atom chip. We measure the microwave field strength in the cavity through observation of the AC shift of the hyperfine transition frequency when the cavity is driven off-resonance from the atomic transition. The measured shifts are used to reconstruct the field in the resonator, in close agreement with transmission measurements of the c...

  16. Evaluation of caesium atomic fountain NICT-CsF1

    International Nuclear Information System (INIS)

    Kumagai, M.; Ito, H.; Kajita, M.; Hosokawa, M.

    2008-01-01

    In this paper, we describe the first caesium atomic fountain primary frequency standard NICT-CsF1 of National Institute of Information Communications Technology (NICT) in Tokyo, Japan. The structure of the NICT-CsF1 system and evaluation procedure of the systematic frequency shifts and their uncertainties are presented. Typically, NICT-CsF1 has a frequency stability of 4 * 10 -13 /τ 1/2 and a frequency uncertainty of 1.9 * 10 -15 . (authors)

  17. Sister chromatoid exchanges in atomic bomb survivors

    International Nuclear Information System (INIS)

    Nakano, Mimako; Awa, Akio

    1980-01-01

    Sister chromatoid exchange (SCE) frequencies in the peripheral lymphocyte with and without mitomycin-C (MMC) were studied, in the age of tens and thirties for an atomic-bomb survivor group and in thirties, fifties, and seventies for an unexposed group. The observation of 100 cells showed no statistically significant difference of SCE frequencies with aging or irradiation. The increasing rates of SCE frequencies by MMC showed no difference among the groups. The average increasing ratio by MMC was 3.6. (Nakanishi, T.)

  18. Microwave multiphoton excitation of helium Rydberg atoms: The analogy with atomic collisions

    International Nuclear Information System (INIS)

    van de Water, W.; van Leeuwen, K.A.H.; Yoakum, S.; Galvez, E.J.; Moorman, L.; Bergeman, T.; Sauer, B.E.; Koch, P.M.

    1989-01-01

    We study multiphoton transitions in helium Rydberg atoms subjected to a microwave electric field of fixed frequency but varying intensity. For each principal quantum number in the range n=25--32, the n 3 S to n 3 (L>2), n=25--32, transition probability exhibits very sharp structures as a function of the field amplitude. Their positions could be reproduced precisely using a Floquet Hamiltonian for the interaction between atom and field. Their shapes are determined by the transients of field turn-on and turn-off in a way that makes a close analogy with the theory of slow atomic collisions

  19. Coherent atomic and molecular spectroscopy in the far infrared

    International Nuclear Information System (INIS)

    Inguscio, M.

    1988-01-01

    Recent advances in far infrared spectroscopy of atoms (fine structure transitions) and molecules (rotational transitions) are reviewed. Results obtained by means of Laser Magnetic Resonance, using fixed frequency lasers, and Tunable Far Infrared spectrometers are illustrated. The importance of far infrared spectroscopy for several fields, including astrophysics, atmospheric physics, atomic structure and metology, is discussed. (orig.)

  20. Research on the Method of Noise Error Estimation of Atomic Clocks

    Science.gov (United States)

    Song, H. J.; Dong, S. W.; Li, W.; Zhang, J. H.; Jing, Y. J.

    2017-05-01

    The simulation methods of different noises of atomic clocks are given. The frequency flicker noise of atomic clock is studied by using the Markov process theory. The method for estimating the maximum interval error of the frequency white noise is studied by using the Wiener process theory. Based on the operation of 9 cesium atomic clocks in the time frequency reference laboratory of NTSC (National Time Service Center), the noise coefficients of the power-law spectrum model are estimated, and the simulations are carried out according to the noise models. Finally, the maximum interval error estimates of the frequency white noises generated by the 9 cesium atomic clocks have been acquired.

  1. Atomic collisions research with excited atomic species

    International Nuclear Information System (INIS)

    Hoogerland, M.D.; Gulley, R.J.; Colla, M.; Lu, W.; Milic, D.; Baldwin, K.G.H.; Buckman, S.J.

    1999-01-01

    Measurements and calculations of fundamental atomic collision and spectroscopic properties such as collision cross sections, reaction rates, transition probabilities etc. underpin the understanding and operation of many plasma and gas-discharge-based devices and phenomena, for example plasma processing and deposition. In almost all cases the complex series of reactions which sustains the discharge or plasma, or produces the reactive species of interest, has a precursor electron impact excitation, attachment, dissociation or ionisation event. These processes have been extensively studied in a wide range of atomic and molecular species and an impressive data base of collision cross sections and reaction rates now exists. However, most of these measurements are for collisions with stable atomic or molecular species which are initially in their ground electronic state. Relatively little information is available for scattering from excited states or for scattering from unstable molecular radicals. Examples of such species would be metastable excited rare gases, which are often used as buffer gases, or CF 2 radicals formed by electron impact dissociation in a CF 4 plasma processing discharge. We are interested in developing experimental techniques which will enable the quantitative study of such exotic atomic and molecular species. In this talk I would like to outline one such facility which is being used for studies of collisions with metastable He(2 3 S) atoms

  2. Remote atomic clock synchronization via satellites and optical fibers

    OpenAIRE

    Piester, D.; Rost, M.; Fujieda, M.; Feldmann, T.; Bauch, A.

    2011-01-01

    In the global network of institutions engaged with the realization of International Atomic Time (TAI), atomic clocks and time scales are compared by means of the Global Positioning System (GPS) and by employing telecommunication satellites for two-way satellite time and frequency transfer (TWSTFT). The frequencies of the state-of-the-art primary caesium fountain clocks can be compared at the level of 10−15 (relative, 1 day averaging) and time scales can be synchronized...

  3. Calcium Atom Trap for Atom Trap Mass Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Kwang Hoon; Park, Hyun Min; Han, Jae Min; Kim, Taek Soo; Cha, Yong Ho; Lim, Gwon; Jeong, Do Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    Trace isotope analysis has been an important role in science, archaeological dating, geology, biology and nuclear industry. Artificially produced fission products such as Sr-90, Cs-135 and Kr-85 can be released to the environment when nuclear accident occurs and the reprocessing factory operates. Thus, the analysis of them has been of interest in nuclear industry. But it is difficult to detect them due to low natural abundance less then 10-10. The ultra-trace radio isotopes have been analyzed by the radio-chemical method, accelerator mass spectrometer, and laser based method. The radiochemical method has been used in the nuclear industry. But this method has disadvantages of long measurement time for long lived radioisotopes and toxic chemical process for the purification. The accelerator mass spectrometer has high isotope selectivity, but the system is huge and it has the isobar effects. The laser based method, such as RIMS (Resonance Ionization Mass Spectrometry) is a basically isobar-effect free method. Recently, ATTA (Atom Trap Trace Analysis), one of the laser based method, has been successfully demonstrated sufficient isotope selectivity with small system size. It has been applied for the detection of Kr-81 and Kr-85. However, it is not suitable for real sample detection, because it requires steady atomic beam generation during detection and is not allowed simultaneous detection of other isotopes. Therefore, we proposed the coupled method of Atom Trap and Mass Spectrometer. It consists of three parts, neutral atom trap, ionization and mass spectrometer. In this paper, we present the demonstration of the magneto-optical trap of neutral calcium. We discuss the isotope selective characteristics of the MOT (Magneto Optical Trap) of calcium by the fluorescence measurement. In addition, the frequency stabilization of the trap beam will be presented

  4. Atoms - molecules - nuclei. Vol. 1

    International Nuclear Information System (INIS)

    Otter, G.; Honecker, R.

    1993-01-01

    This first volume covers the following topics: Wave-particle dualism, classical atomic physics; the Schroedinger equation, angular momentum in quantum physics, one-electron atoms and many-electron atoms with atomic structure, atomic spectra, exotic atoms, influence of electric and magnetic fields

  5. 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}.

  6. Precision spectroscopy on atomic hydrogen

    International Nuclear Information System (INIS)

    Parthey, Christian Godehard

    2011-01-01

    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 Δ∫ exp =670 994 334 606(15) Hz. Comparing with the theoretical value for the isotope shift, excluding the leading nuclear size effect, Δ∫ 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 2 right angle d - left angle r 2 right angle p =3.82007(65) fm 2 and the deuteron structure radius r 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 ∫ 1S-2S =2 466 061 413 187 035 (10) Hz which presents a fractional frequency uncertainty of 4.2 x 10 -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 ∫ 1S-2S =2 466 061 413 187 017 (11) Hz we can put a constraint on the electron Lorentz boost violating coefficients 0.95c (TX) -0.29c (TY) -0.08 c (TZ) =(2.2±1.8) x 10 -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 (∂)/(∂t)ln (μ Cs )/(μ B )=-(3.0±1.2) x 10 -15 yr -1 .

  7. Atomic and molecular sciences

    International Nuclear Information System (INIS)

    Lane, N.F.

    1989-01-01

    The theoretical atomic and molecular physics program at Rice University addresses basic questions about the collision dynamics of electrons, atoms, ions and molecules, emphasizing processes related to possible new energy technologies and other applications. The program focuses on inelastic collision processes that are important in understanding energy and ionization balance in disturbed gases and plasmas. Emphasis is placed on systems and processes where some experimental information is available or where theoretical results may be expected to stimulate new measurements. Examples of current projects include: excitation and charge-transfer processes; orientation and alignment of excited states following collisions; Rydberg atom collisions with atoms and molecules; Penning ionization and ion-pair formation in atom-atom collisions; electron-impact ionization in dense, high-temperature plasmas; electron-molecule collisions; and related topics

  8. Construction of localized atomic wave packets

    International Nuclear Information System (INIS)

    Ranjani, S Sree; Kapoor, A K; Panigrahi, P K

    2010-01-01

    It is shown that highly localized solitons can be created in lower dimensional Bose-Einstein condensates (BECs), trapped in a regular harmonic trap, by temporally varying the trap frequency. A BEC confined in such a trap can be effectively used to construct a pulsed atomic laser emitting coherent atomic wave packets. In addition to having a complete control over the spatio-temporal dynamics of the solitons, we can separate the equation governing the Kohn mode (centre of mass motion). We investigate the effect of the temporal modulation of the trap frequency on the spatio-temporal dynamics of the bright solitons and also on the Kohn mode. The dynamics of the solitons and the variations in the Kohn mode with time are compared with those in a BEC confined in a trap with unmodulated trap frequency.

  9. Metal atom oxidation laser

    International Nuclear Information System (INIS)

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-01-01

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides

  10. 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.

  11. Economical Atomic Layer Deposition

    Science.gov (United States)

    Wyman, Richard; Davis, Robert; Linford, Matthew

    2010-10-01

    Atomic Layer Deposition is a self limiting deposition process that can produce films at a user specified height. At BYU we have designed a low cost and automated atomic layer deposition system. We have used the system to deposit silicon dioxide at room temperature using silicon tetrachloride and tetramethyl orthosilicate. Basics of atomic layer deposition, the system set up, automation techniques and our system's characterization are discussed.

  12. Atomic physics made clear

    International Nuclear Information System (INIS)

    Meinhold, H.

    1980-01-01

    This book is a popular introduction into the foundations of atomic physics und quantum mechanics. Starting from some phenomenological concepts Bohr's model and the construction of the periodic system regarding the shell structure of atoms are introduced. In this framework the selection rules and magnetic moments of atomic electrons are considered. Finally the wave-particle dualism is considered. In the appendix some mathematical methods are described which are useful for a deeper penetration into the considered ideas. (HSI)

  13. Deeply bound pionic atom

    International Nuclear Information System (INIS)

    Toki, Hiroshi; Yamazaki, Toshimitsu

    1989-01-01

    The standard method of pionic atom formation does not produce deeply bound pionic atoms. A study is made on the properties of deeply bound pionic atom states by using the standard pion-nucleus optical potential. Another study is made to estimate the cross sections of the formation of ls pionic atom states by various methods. The pion-nucleus optical potential is determined by weakly bound pionic atom states and pion nucleus scattering. Although this potential may not be valid for deeply bound pionic atoms, it should provide some hint on binding energies and level widths of deeply bound states. The width of the ls state comes out to be 0.3 MeV and is well separated from the rest. The charge dependence of the ls state is investigated. The binding energies and the widths increase linearly with Z azbove a Z of 30. The report then discusses various methods to populate deeply bound pionic atoms. In particular, 'pion exchange' reactions are proposed. (n, pπ) reaction is discussed first. The cross section is calculated by assuming the in- and out-going nucleons on-shell and the produced pion in (n1) pionic atom states. Then, (n, dπ - ) cross sections are estimated. (p, 2 Heπ - ) reaction would have cross sections similar to the cross section of (n, dπ - ) reaction. In conclusion, it seems best to do (n, p) experiment on heavy nuclei for deeply bound pionic atom. (Nogami, K.)

  14. Single atom oscillations

    International Nuclear Information System (INIS)

    Wiorkowski, P.; Walther, H.

    1990-01-01

    Modern methods of laser spectroscopy allow the study of single atoms or ions in an unperturbed environment. This has opened up interesting new experiments, among them the detailed study of radiation-atom coupling. In this paper, the following two experiments dealing with this problem are reviewed: the single-atom maser and the study of the resonance fluorescence of a single stored ion. The simplest and most fundamental system for studying radiation-matter coupling is a single two-level atom interacting with a single mode of an electromagnetic field in a cavity. This problem received a great deal of attention shortly after the maser was invented

  15. Atomic hydrogen reactor

    International Nuclear Information System (INIS)

    Massip de Turville, C.M.D.

    1982-01-01

    Methods are discussed of generating heat in an atomic hydrogen reactor which involve; the production of atomic hydrogen by an electrical discharge, the capture of nascent neutrons from atomic hydrogen in a number of surrounding steel alloy tubes having a high manganese content to produce 56 Mn, the irradiation of atomic hydrogen by the high energy antineutrinos from the beta decay of 56 Mn to yield nascent neutrons, and the removal of the heat generated by the capture of nascent neutrons by 55 Mn and the beta decay of 56 Mn. (U.K.)

  16. Atomic Covalent Functionalization of Graphene

    Science.gov (United States)

    Johns, James E.; Hersam, Mark C.

    2012-01-01

    Conspectus Although graphene’s physical structure is a single atom thick, two-dimensional, hexagonal crystal of sp2 bonded carbon, this simple description belies the myriad interesting and complex physical properties attributed to this fascinating material. Because of its unusual electronic structure and superlative properties, graphene serves as a leading candidate for many next generation technologies including high frequency electronics, broadband photodetectors, biological and gas sensors, and transparent conductive coatings. Despite this promise, researchers could apply graphene more routinely in real-world technologies if they could chemically adjust graphene’s electronic properties. For example, the covalent modification of graphene to create a band gap comparable to silicon (~1 eV) would enable its use in digital electronics, and larger band gaps would provide new opportunities for graphene-based photonics. Towards this end, researchers have focused considerable effort on the chemical functionalization of graphene. Due to its high thermodynamic stability and chemical inertness, new methods and techniques are required to create covalent bonds without promoting undesirable side reactions or irreversible damage to the underlying carbon lattice. In this Account, we review and discuss recent theoretical and experimental work studying covalent modifications to graphene using gas phase atomic radicals. Atomic radicals have sufficient energy to overcome the kinetic and thermodynamic barriers associated with covalent reactions on the basal plane of graphene but lack the energy required to break the C-C sigma bonds that would destroy the carbon lattice. Furthermore, because they are atomic species, radicals substantially reduce the likelihood of unwanted side reactions that confound other covalent chemistries. Overall, these methods based on atomic radicals show promise for the homogeneous functionalization of graphene and the production of new classes of two

  17. Atom dynamics in laser fields

    International Nuclear Information System (INIS)

    Jang, Su; Mi, No Gin

    2004-12-01

    This book introduces coherent dynamics of internal state, spread of atoms wave speed, semiclassical atoms density matrix such as dynamics equation in both still and moving atoms, excitation of atoms in movement by light, dipole radiating power, quantum statistical mechanics by atoms in movement, semiclassical atoms in movement, atoms in movement in the uniform magnetic field including effects of uniform magnetic field, atom cooling using laser such as Doppler cooling, atom traps using laser and mirrors, radiant heat which particles receive, and near field interactions among atoms in laser light.

  18. Eco-eficiência na produção de cera de Carnaúba no município de Campo Maior, Piauí, 2004

    Directory of Open Access Journals (Sweden)

    Francisco Prancacio Araújo de Carvalho

    2008-06-01

    Full Text Available A Copernicia prunifera (Miller H.E. Moore ou carnaúba gera um material sobre as folhas usado na fabricação de cera, matéria-prima de inúmeros produtos industriais. O Brasil é o único produtor de cera de carnaúba e o estado do Piauí, um importante influente. Neste, as condições naturais do município de Campo Maior favorecem a incidência da carnaubeira e sua tradição histórica na produção de cera tornaram-no um pólo regional. O objetivo geral é analisar, na produção de cera de carnaúba, os elementos e indicadores de eco-eficiência - associação de eficiência econômica com baixo impacto ambiental -, os específicos são: avaliar qualitativamente o consumo de materiais e de energia, emissão de substâncias tóxicas, existência de reciclagem de materiais e uso de recursos renováveis; construir e analisar indicadores de ecoeficiência. As informações e dados originaram-se de pesquisa direta em indústria de cera que representasse o padrão técnico e a participação no mercado no estado. Os resultados mostram que a produção industrial de cera impacta o meio ambiente com uso intenso de água, utilização da lenha e diesel como fonte energética, consumo de produtos químicos e emissão de poluentes, entretanto, atende importantes elementos de eco-eficiência como a reutilização de materiais e consumo de materiais renováveis.The Copernicia prunifera (Miller H.E. Moore or "carnauba" generates a material from the leaves used in the wax production, raw material of countless industrial products. Brazil is the only producer of carnauba wax and the state of Piauí, an important influential. In this, the natural conditions of the district of Campo Maior favor the incidence of the carnauba and its historical tradition in the wax production, turned it a regional pole. The general goal is to analyze, in the carnauba wax production, the elements and the eco-efficiency indicators - economical efficiency associated with low

  19. Atoms stories; Histoire d`atomes

    Energy Technology Data Exchange (ETDEWEB)

    Radvanyi, P; Bordry, M [Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France)

    1988-12-31

    Physicists from different countries told each evening during one learning week, to an audience of young people, some great discoveries in evoking the difficulties and problems to which the researchers were confronted. From Antiquity to a more recent history, it is a succession of atoms stories. (N.C.)

  20. Low energy atom-atom collisions

    International Nuclear Information System (INIS)

    Child, M.S.

    1980-01-01

    The semiclassical theory of atom-atom potential scattering and of low energy inelastic atom-atom scattering is reviewed. Particular attention is given to the origin and interpretation of rainbow structure, diffraction oscillations and exchange oscillations in the potential scattering differential cross-section, and to the glory structure and symmetry oscillations in the integral cross-section. Available methods for direct inversion of the cross-section data to recover the potential are reviewed in some detail. The theory of non-adiabatic transitions is introduced by a short discussion of interaction mechanisms and of diabetic and adiabatic representations. Analytical S matrix elements are presented for two state curve-crossing (Landau-Zener-Stuckelberg), Demkov and Nikitin models. The relation between Stuckelberg oscillations in the S matrix and in the differential cross-section is discussed in terms of interference between trajectories belonging to two different classical deflection functions. The energy dependences of the inelastic integral cross-section for curve-crossing and Demkov type transitions are also discussed. Finally the theory is reviewed in relation to a recent close-coupled study of fine structure transitions in F( 2 P) + Xe( 2 S) scattering

  1. Atom-atom interactions around the band edge of a photonic crystal waveguide

    Science.gov (United States)

    Hood, Jonathan D.; Goban, Akihisa; Asenjo-Garcia, Ana; Lu, Mingwu; Yu, Su-Peng; Chang, Darrick E.; Kimble, H. J.

    2016-09-01

    Tailoring the interactions between quantum emitters and single photons constitutes one of the cornerstones of quantum optics. Coupling a quantum emitter to the band edge of a photonic crystal waveguide (PCW) provides a unique platform for tuning these interactions. In particular, the cross-over from propagating fields E(x)∝e±ikxxE(x)∝e±ikxx outside the bandgap to localized fields E(x)∝e-κx|x|E(x)∝e-κx|x| within the bandgap should be accompanied by a transition from largely dissipative atom-atom interactions to a regime where dispersive atom-atom interactions are dominant. Here, we experimentally observe this transition by shifting the band edge frequency of the PCW relative to the D1D1 line of atomic cesium for N¯=3.0±0.5N¯=3.0±0.5 atoms trapped along the PCW. Our results are the initial demonstration of this paradigm for coherent atom-atom interactions with low dissipation into the guided mode.

  2. Atom-resolved AFM imaging of calcite nanoparticles in water

    Energy Technology Data Exchange (ETDEWEB)

    Imada, Hirotake; Kimura, Kenjiro [Department of Chemistry, School of Science, Kobe University, Rokko-dai, Nada, Kobe 657-8501 (Japan); Onishi, Hiroshi, E-mail: oni@kobe-u.ac.jp [Department of Chemistry, School of Science, Kobe University, Rokko-dai, Nada, Kobe 657-8501 (Japan)

    2013-06-20

    Highlights: ► An advanced frequency-modulation AFM (FM-AFM) was applied for imaging particles. ► Atom-resolved topography of nano-sized particles of calcite was observed in water. ► Locally ordered structures were found and assigned to a (104) facet of calcite. ► A promising ability of FM-AFM was demonstrated in imaging nano-sized particles. - Abstract: The atom-resolved topography of calcite nanoparticles was observed in water using a frequency-modulation atomic force microscope. Locally ordered structures were found and assigned to a (104) facet of crystalline calcite.

  3. Atom-resolved AFM imaging of calcite nanoparticles in water

    International Nuclear Information System (INIS)

    Imada, Hirotake; Kimura, Kenjiro; Onishi, Hiroshi

    2013-01-01

    Highlights: ► An advanced frequency-modulation AFM (FM-AFM) was applied for imaging particles. ► Atom-resolved topography of nano-sized particles of calcite was observed in water. ► Locally ordered structures were found and assigned to a (104) facet of calcite. ► A promising ability of FM-AFM was demonstrated in imaging nano-sized particles. - Abstract: The atom-resolved topography of calcite nanoparticles was observed in water using a frequency-modulation atomic force microscope. Locally ordered structures were found and assigned to a (104) facet of crystalline calcite

  4. Contribution to coherent atom optics - Design of multiple wave devices

    International Nuclear Information System (INIS)

    Impens, F.

    2008-03-01

    The theoretical work presented in this manuscript addresses two complementary issues in coherent atom optics. The first part addresses the perspectives offered by coherent atomic sources through the design of two experiment involving the levitation of a cold atomic sample in a periodic series of light pulses, and for which coherent atomic clouds are particularly well-suited. These systems appear as multiple wave atom interferometers. A striking feature of these experiments is that a unique system performs both the sample trapping and interrogation. To obtain a transverse confinement, a novel atomic lens is proposed, relying on the interaction between an atomic wave with a spherical light wave. The sensitivity of the sample trapping towards the gravitational acceleration and towards the pulse frequencies is exploited to perform the desired measurement. These devices constitute atomic wave resonators in momentum space, which is a novel concept in atom optics. A second part develops new theoretical tools - most of which inspired from optics - well-suited to describe the propagation of coherent atomic sources. A phase-space approach of the propagation, relying on the evolution of moments, is developed and applied to study the low-energy dynamics of Bose-Einstein condensates. The ABCD method of propagation for atomic waves is extended beyond the linear regime to account perturbatively for mean-field atomic interactions in the atom-optical aberration-less approximation. A treatment of the atom laser extraction enabling one to describe aberrations in the atomic beam, developed in collaboration with the Atom Optics group at the Institute of Optics, is exposed. Last, a quality factor suitable for the characterization of diluted matter waves in a general propagation regime has been proposed. (author)

  5. 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.

  6. Atomic Energy Control Board

    International Nuclear Information System (INIS)

    Blackman, N.S.; Gummer, W.K.

    1982-02-01

    This paper has been prepared to provide an overview of the responsibilities and activities of the Atomic Energy Control Board. It is designed to address questions that are often asked concerning the establishment of the Atomic Energy Control Board, its enabling legislation, licensing and compliance activities, federal-provincial relationships, international obligations, and communications with the public

  7. mu. -nucleon atoms

    Energy Technology Data Exchange (ETDEWEB)

    Dobretsov, Yu; Dolgoshein, B; Kirillov-Ugryumov, V

    1980-12-01

    The properties and formation are described of ..mu..-nucleon atoms, the Larmor method of muon spin precession is discussed and the experimental confirmation of the existence of ..mu..-nucleon atoms is shown. The prospects of their use are indicated.

  8. μ-nucleon atoms

    International Nuclear Information System (INIS)

    Dobretsov, Yu.; Dolgoshejn, B.; Kirillov-Ugryumov, V.

    1980-01-01

    The properties and formation are described of μ-nucleon atoms, the Larmor method of muon spin precession is discussed and the experimental confirmation of the existence of μ-nucleon atoms is shown. The prospects of their use are indicated. (J.P.)

  9. Atomic Ferris wheel beams

    Science.gov (United States)

    Lembessis, Vasileios E.

    2017-07-01

    We study the generation of atom vortex beams in the case where a Bose-Einstein condensate, released from a trap and moving in free space, is diffracted from a properly tailored light mask with a spiral transverse profile. We show how such a diffraction scheme could lead to the production of an atomic Ferris wheel beam.

  10. Atom lithography of Fe

    NARCIS (Netherlands)

    Sligte, te E.; Smeets, B.; van der Stam, K.M.R.; Herfst, R.W.; Straten, van der P.; Beijerinck, H.C.W.; Leeuwen, van K.A.H.

    2004-01-01

    Direct write atom lithography is a technique in which nearly resonant light is used to pattern an atom beam. Nanostructures are formed when the patterned beam falls onto a substrate. We have applied this lithography scheme to a ferromagnetic element, using a 372 nm laser light standing wave to

  11. Beyond the Atom

    Science.gov (United States)

    Cox, John

    2011-08-01

    1. Introduction - the atom in the seventies; 2. The vacuum tube; 3. The new rays; 4. The new substances; 5. Disintegration; 6. A family tree; 7. Verifications and results; 8. The objective reality of molecules; 9. The new atom; Bibliography; Index.

  12. 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…

  13. Atom electron scattering

    International Nuclear Information System (INIS)

    Santoso, B.

    1976-01-01

    Green Lippmann-Schwinger functions operator representations, derivation of perturbation method using Green function and atom electron scattering, are discussed. It is concluded that by using complex coordinate places where resonances occur, can be accurately identified. The resonance can be processed further for practical purposes, for example for the separation of atom. (RUW)

  14. Atomic energy for progress

    International Nuclear Information System (INIS)

    1974-01-01

    The film discusses the functions and activities of the Philippine Atomic Energy Commission. Shown are the applications of atomic energy in research, agriculture, engineering, industry and medicine, as well as the construction of the research reactor and its inauguration by President Marcos

  15. Zeeman atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Loos-Vollebregt, M.T.C. de.

    1980-01-01

    A new method of background correction in atomic absorption spectroscopy has recently been introduced, based on the Zeeman splitting of spectral lines in a magnetic field. A theoretical analysis of the background correction capability observed in such instruments is presented. A Zeeman atomic absorption spectrometer utilizing a 50 Hz sine wave modulated magnetic field is described. (Auth.)

  16. Isotopes and atomic weights

    International Nuclear Information System (INIS)

    Zhang Qinglian

    1990-01-01

    A review of the chemical and mass spectrometric methods of determining the atomic weights of elements is presented. A, special discussion is devoted to the calibration of the mass spectrometer with highly enriched isotopes. It is illustrated by the recent work on europium. How to choose the candidate element for new atomic weight determination forms the last section of the article

  17. Association of atoms into universal dimers using an oscillating magnetic field.

    Science.gov (United States)

    Langmack, Christian; Smith, D Hudson; Braaten, Eric

    2015-03-13

    In a system of ultracold atoms near a Feshbach resonance, pairs of atoms can be associated into universal dimers by an oscillating magnetic field with a frequency near that determined by the dimer binding energy. We present a simple expression for the transition rate that takes into account many-body effects through a transition matrix element of the contact. In a thermal gas, the width of the peak in the transition rate as a function of the frequency is determined by the temperature. In a dilute Bose-Einstein condensate of atoms, the width is determined by the inelastic scattering rates of a dimer with zero-energy atoms. Near an atom-dimer resonance, there is a dramatic increase in the width from inelastic atom-dimer scattering and from atom-atom-dimer recombination. The recombination contribution provides a signature for universal tetramers that are Efimov states consisting of two atoms and a dimer.

  18. O cooperativismo e a gestão dos riscos de mercado: análise da fronteira de eficiência do agronegócio paranaense

    Directory of Open Access Journals (Sweden)

    Vilmar Rodrigues Moreira

    2012-03-01

    Full Text Available O artigo discute a gestão dos riscos de mercado do agronegócio, a influência das cooperativas agroindustriais nesta prática e avalia o portfólio de produção de commodities agropecuárias do Paraná, considerando a relação retorno-risco. Por meio da construção de uma fronteira de eficiência foi possível verificar quais seriam as mudanças necessárias no portfólio de produção do estado visando à eficiência econômica (definida neste trabalho como o trade-off entre retorno e risco. O artigo também avalia o grau de participação das cooperativas agroindustriais na produção dos itens considerados no modelo e quais as possíveis influências que este tipo de organização poderia exercer nas alterações das preferências de produção. Por meio de questionários e entrevistas com gestores de cooperativas foi avaliada a disposição em incentivar mudanças nos portfólios de produção das cooperativas e dos cooperados. Verificou-se que os principais motivos que influenciam as decisões sobre produção estão relacionados a aspectos econômicos e racionais, como foco estratégico da cooperativa e resistências dos cooperados. No contexto paranaense, os motivos relacionados a aspectos políticos ou sociais, inerentes às características organizacionais das cooperativas, não exercem influência significativa nas decisões sobre diversificação como instrumento para a gestão dos riscos de mercado.

  19. Eficiência da seleção de progênies de café F4 pela metodologia de modelos mistos (REML/BLUP

    Directory of Open Access Journals (Sweden)

    Thamiris Bandoni Pereira

    2013-01-01

    Full Text Available Objetivou-se verificar a eficiência da seleção de cafeeiros em geração F4 para características agronômicas e resistência a doenças mediante o emprego da metodologia de modelos mistos de Henderson. O experimento foi instalado na Fazenda Experimental da EPAMIG, em Machado, MG, sendo utilizadas progênies F4 derivadas do cruzamento entre cultivares do grupo Icatu com Catuaí Amarelo IAC 62 e IAC 17 e com as progênies IAC 5002 e IAC 5010. O delineamento experimental utilizado foi o látice com quatro repetições e as avaliações foram realizadas ao longo de dois anos (2010 e 2011. Foram avaliadas as seguintes características: produção (litros planta-1, reação à ferrugem, vigor vegetativo e reação à cercosporiose. Foram utilizados o procedimento REML/BLUP para estimar os parâmetros genéticos, o índice de seleção de Mulamba e Mock a fim de verificar os ganhos para múltiplos caracteres, a acurácia e eficiência, calculadas a partir do diferente número de medições e, ainda, o agrupamento multivariado de progênies pelo método de Tocher. Verificou-se, a partir da análise dos parâmetros genéticos, um maior sucesso na seleção entre famílias para todas as características avaliadas. A adoção de quatro colheitas poderá elevar a acurácia a 80% na seleção de indivíduos para as características produção, reação à ferrugem e vigor vegetativo. A seleção das 12 melhores progênies para caracteres múltiplos pelo índice de Mulamba e Mock proporcionaria um ganho médio de 70,4%.

  20. Efficiency of oxygen: absorbing sachets in different relative humidities and temperatures Eficiência de absorvedores de oxigênio sob diferentes umidades relativas e temperaturas

    Directory of Open Access Journals (Sweden)

    Renato Souza Cruz

    2007-12-01

    Full Text Available The main objective of this work was to evaluate the efficiency of oxygen - absorbing sachets at relative humidity of 75%, 80% and 85% and different temperatures, 10±2 ºC and 25±2 ºC. The experiment consisted in determining the O2 absorption under these conditions. A sachet was placed in desiccators with an internal air homogenization system. Aliquots of air were removed at pre-established time intervals and analyzed for oxygen content. The results showed that oxygen absorption by the sachet increased as the relative humidity increased for both temperature. Therefore the oxygen - absorbing sachets were most active under 25±2ºC and 85% relative humidity. At ambient condition (25±2ºC/75%RH the rate of oxygen absorbed was 50 mL/day and 18,5 mL/day for 10±2ºC. It was used a totally casualized design with three replicates.O objetivo principal deste trabalho foi avaliar a eficiência de sachês absorvedores de oxigênio a 75%, 80% e 85% de umidade relativa e diferentes temperaturas, 10±2 ºC e 25±2 ºC. O experimento consiste em determinar a absorção de O2 sob essas condições. Um sachê foi colocado dentro de um dessecador contendo um sistema de homogeneização do ar interno. Alíquotas de ar são retiradas dos dessecadores em intervalos de tempos pré-estabelecido e seu conteúdo de oxigênio analisado. Os resultados mostraram que a absorção de oxigênio pelos saches aumentaram com o aumento da temperatura para ambas as temperaturas. No entanto, os sachês mostraram uma maior eficiência para 85% de umidade relativa e 25±2ºC de temperatura. Na condição ambiente (25±2ºC/75%RH, a taxa de absorção dos sachês foi de 50 mL/dia e 18,5 mL/dia para 10±2ºC. O experimento foi conduzido com delineamento experimental inteiramente casualizado, com três repetições.

  1. Two-photon cooling of magnesium atoms

    DEFF Research Database (Denmark)

    Malossi, N.; Damkjær, S.; Hansen, P. L.

    2005-01-01

    A two-photon mechanism for cooling atoms below the Doppler temperature is analyzed. We consider the magnesium ladder system (3s2)S01¿(3s3p)P11 at 285.2nm followed by the (3s3p)P11¿(3s3d)D21 transition at 880.7nm . For the ladder system quantum coherence effects may become important. Combined with...... and experiment is excellent. In addition, by properly choosing the Rabi frequencies of the two optical transitions a velocity independent atomic dark state is observed....

  2. Transient localization in the kicked Rydberg atom

    International Nuclear Information System (INIS)

    Persson, Emil; Fuerthauer, S.; Burgdoerfer, J.; Wimberger, S.

    2006-01-01

    We investigate the long-time limit of quantum localization of the kicked Rydberg atom. The kicked Rydberg atom is shown to possess in addition to the quantum localization time τ L a second crossover time t D where quantum dynamics diverges from classical dynamics towards increased instability. The quantum localization is shown to vanish as either the strength of the kicks at fixed principal quantum number or the quantum number at fixed kick strength increases. The survival probability as a function of frequency in the transient localization regime τ L D is characterized by highly irregular, fractal-like fluctuations

  3. 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...

  4. 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...

  5. Antiprotonic-hydrogen atoms

    International Nuclear Information System (INIS)

    Batty, C.J.

    1989-07-01

    Experimental studies of antiprotonic-hydrogen atoms have recently made great progress following the commissioning of the low energy antiproton facility (LEAR) at CERN in 1983. At the same time our understanding of the atomic cascade has increased considerably through measurements of the X-ray spectra. The life history of the p-bar-p atom is considered in some detail, from the initial capture of the antiproton when stopping in hydrogen, through the atomic cascade with the emission of X-rays, to the final antiproton annihilation and production of mesons. The experiments carried out at LEAR are described and the results compared with atomic cascade calculations and predictions of strong interaction effects. (author)

  6. Teste de eficiência de vacinas antiaftosa. II. Relação entre o Índice C em cobaias e o Índice Proteção Camundongos

    Directory of Open Access Journals (Sweden)

    Ernani Ibirá Gonçalves

    1994-03-01

    Full Text Available O exame da eficiência de seis vacinas antiaftosa, realizado com os testes “Indice Proteção Camundongos” e "Índice C” utilizando 15 ou mais cobaias por diluição de vírus na titulação, demonstrou a presença de boa correlação e alta significância entre os resultados das duas provas. O valor do índice Proteção Camundongos foi aproximadamente o dobro do valor do índice C. Assim, o índice Proteção Camundongos pode ser recomendado como teste de eficiência de vacinas antiaftosa. principalmente quando se necessita um grande número de provas, devido a seu baixo custo e facilidade de execução, por usar exclusivamente camundongos.

  7. Eficiência de uso do fósforo em sistemas de manejo do solo e adubação fosfatada por um longo período

    OpenAIRE

    Nunes, Rafael de Souza

    2014-01-01

    Por ser obtido a partir de um recurso natural não renovável, o fertilizante fosfatado deve ser usado de forma a maximizar sua eficiência de uso. No entanto, o melhor entendimento do efeito de práticas agrícolas nesse processo só pode ser obtido em experimentos de longa duração. O objetivo deste trabalho foi compreender os efeitos do sistema de manejo do solo e da adubação fosfatada por um longo período na produtividade de grãos e eficiência de uso do fósforo por soja e milho. Para isso, um La...

  8. Cooling and trapping neutral atoms with radiative forces

    International Nuclear Information System (INIS)

    Bagnato, V.S.; Castro, J.C.; Li, M.S.; Zilio, S.C.

    1988-01-01

    Techniques to slow and trap neutral atoms at high densities with radiative forces are discussed in this review articles. Among several methods of laser cooling, it is emphasized Zeeman Tuning of the electronic levels and frequency-sweeping techniques. Trapping of neutral atoms and recent results obtained in light and magnetic traps are discussed. Techniques to further cool atoms inside traps are presented and the future of laser cooling of neutral atoms by means of radiation pressure is discussed. (A.C.A.S.) [pt

  9. Laser trapping of radioactive francium atoms

    International Nuclear Information System (INIS)

    Sprouse, G.D.; Orozco, L.A.; Simsarian, J.E.; Shi, W.; Zhao, W.Z.

    1997-01-01

    The difficult problem of quickly slowing and cooling nuclear reaction products so that they can be injected into a laser trap has been solved by several groups and there are now strong efforts to work with the trapped atoms. The atoms are confined in the trap to a small spatial volume of the order of 1 mm 3 , but more importantly, they are also confined in velocity, which makes them an ideal sample for spectroscopic measurements with other lasers. We have recently trapped radioactive francium and have embarked on a program to further study the francium atom as a prelude to a test of the Standard Model analogous to previous work with Cs. Our sample of 3 min 210 Fr now contains over 20 000 atoms, and is readily visible with an ordinary TV camera. We work on-line with the accelerator, and continuously load the trap to replace losses due to decay and collisions with background gas. We have maintained a sample of Fr atoms in the trap for over 10 hours, with occasional adjustment of the trapping laser frequency to account for drifts. The proposed test of the Standard Model will require accurate calculation of its atomic properties. We are currently testing these calculations by measuring other predicted quantities. (orig.)

  10. Eficiência de extratos vegetais e urina de vaca no controle de Neoleucinodes elegantalis (Guenée, 1854 (Lepidoptera: Pyralidae e Bemisia sp (Hemiptera: Aleurodidae em tomateiro orgânico

    Directory of Open Access Journals (Sweden)

    Maria Socorro Rocha Melo Peixoto

    2013-05-01

    Full Text Available O cultivo do tomateiro (Lycopersicum esculentum Mill ocupa o segundo lugar entre as culturas oleráceas no Brasil (IBGE, 2008, GRAVENA, 1998. Com a expansão da cultura, devido suas qualidades organolépticas, fonte natural de vitaminas, sais minerais e outros metabólitos entre eles o licopeno, os problemas fitossanitários vêm-se agravando. Assim é que, desde a semeadura até a colheita, grande número de pragas e doenças ocorre na cultura do tomateiro. Considerando-se a carência de estudos voltados para utilização de plantas com ação inseticidas e urina de vaca, esse trabalho tem como objetivo avaliar suas eficiências no controle de N. elegantalis e Bemisia sp na cultura do tomate. A pesquisa foi desenvolvida em área experimental da Escola Agrícola “Assis Chateaubriand” e no Núcleo de Manejo de Pragas pertencentes a Universidade Estadual da Paraíba. Resultados: Constatou-se que a associação dos produtos químicos com dipel apresentou maior eficiência no controle para N. elegantalise Bemisia na fase pupal de 95 e 93%, respectivamente em relação aos demais produtos testados. Dentre os tratamentos alternativos a melhor eficiência para N. elegantalis foi obtida com extrato de faveleira (53,6% e extrato de óleo de neem (43,9%, já para a fase pulpal da Bemisia o extrato de óleo de neem apresentou 66,3% de eficiência, em aplicações a cada 4 dias.  Palavras - chave: pragas, extratos vegetais, tomateiro.

  11. Eficiência no uso da água na cana-de-açúcar sob diferentes lâminas de irrigação e níveis de zinco no litoral paraibano Water use efficiency in sugarcane crop under different depths of irrigation and zinc doses in coastal region of Paraíba, Brazil

    Directory of Open Access Journals (Sweden)

    Carlos H. A. Farias

    2008-09-01

    Full Text Available Esta pesquisa foi conduzida em área experimental da Fazenda Capim II, localizada no Município de Capim - PB, com o intuito de determinar a eficiência no uso da água (EUA pela cana-de-açúcar (Saccharum officinarum L., cultivar SP 79-1011. O delineamento experimental consistiu em blocos casualizados, com três repetições, em esquema fatorial 5 x 5. Os tratamentos referentes à lâmina de irrigação foram: sequeiro; 25; 50; 75 e 100% da ETc (1.026,57 mm com as respectivas precipitações efetivas de 780,06; 713,31; 487,54; 243,71 e 194,51 mm; os níveis de zinco estudados foram 0; 1; 2; 3 e 4 kg ha-1. O equipamento de irrigação utilizado foi do tipo pivô central, com turno de rega de nove dias. A eficiência no uso da água (EUA na produção de colmos e de açúcar aumenta à medida que se eleva a lâmina total de água aplicada à cultura. Para a região norte-paraibana dos tabuleiros costeiros, a EUA na produção de colmo e de açúcar, de forma maximizada, é 7,12 e 0,67 kg m-3, respectivamente.The study was conducted in an experimental area of the Capim II Farm, located in the municipality of Capim - PB, Brazil, with the objective of determining the efficiency in the use of the water (WUE for the sugarcane crop (Saccharum officinarum L., cultivar SP 79-1011. The experimental design consisted of randomized blocks, with three replications in a 5 x 5 factorial design. The irrigation treatments were: rainfed; 25; 50; 75 and 100% of the ETc (1,026.57 mm with the respective effective precipitations of 780.06; 713.31; 487.54; 243.71 and 194.51 mm. The levels of zinc studied were 0; 1; 2; 3 and 4 kg ha-1. The irrigation equipment used in the study was a central pivot with irrigation frequency of nine days. The water use efficiency (WUE of sugarcane crop in terms of cane production and of sugar increased with the depth of water applied. For the Coastal Table Lands of northern Paraiba, the maximized WUE for sugarcane and sugar production is

  12. Beams made of twisted atoms: A theoretical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hayrapetyan, Armen [Physikalisches Institut, Ruprecht-Karls-Universitaet Heidelberg, 69120 Heidelberg (Germany); Matula, Oliver [Physikalisches Institut, Ruprecht-Karls-Universitaet Heidelberg, 69120 Heidelberg (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Surzhykov, Andrey [Helmholtz-Institut Jena, 07743 Jena (Germany); Fritzsche, Stephan [Helmholtz-Institut Jena, 07743 Jena (Germany); Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universitaet Jena, 07743 Jena (Germany)

    2014-07-01

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

  13. Efeito do conteúdo e da natureza da lignina residual na eficiência e na seletividade do branqueamento com ozônio Effect of residual lignin content and nature on the efficiency and selectivity of ozone bleaching

    Directory of Open Access Journals (Sweden)

    Elenice Pereira Maia

    2003-04-01

    Full Text Available Neste estudo foram avaliados os efeitos do conteúdo e da natureza da lignina residual na eficiência e na seletividade do branqueamento com ozônio de polpa kraft convencional (kraft e pré-deslignificada com oxigênio (kraft-O. Constatou-se que a eficiência do branqueamento com ozônio se eleva com o aumento do conteúdo de lignina residual da polpa. O tratamento com ozônio é mais seletivo para polpas kraft-O, mas para um mesmo tipo de polpa a seletividade de branqueamento com ozônio se eleva com o aumento de lignina residual. A eficiência do branqueamento com ozônio aumenta com o teor de lignina fenólica na polpa, entretanto a seletividade é negativamente afetada pela presença destas estruturas.This study aimed to evaluate the effect of residual lignin content and nature on the efficiency and selectivity of ozone bleaching of conventional (kraft and oxygen delignified (kraft-O pulps. Ozone bleaching efficiency was found to be enhanced by increasing pulp residual lignin content. Ozone treatment is more selective for kraft-O pulps, but for a given type of pulp (kraft or kraft-O, ozone bleaching selectivity increases with increasing pulp lignin content. Ozone bleaching efficiency increases with increasing pulp lignin phenolic hydroxyl content whereas selectivity is negatively affected by these structures.

  14. Eficiência de inseticidas em tratamento de sementes de milho no controle da cigarrinha Dalbulus maidis (Hemiptera: Cicadellidae em viveiro telado Insecticides efficiency in treatment of corn seeds to control leafhopper Dalbulus maidis (Hemiptera: Cicadellidae in greenhouse

    Directory of Open Access Journals (Sweden)

    Charles Martins de Oliveira

    2008-02-01

    Full Text Available O objetivo deste trabalho foi verificar a eficiência de inseticidas no tratamento de sementes no controle da cigarrinha-do-milho em viveiro telado. Sementes de milho foram tratadas ou não com inseticidas (imidacloprid, thiamethoxan, thiodicarb + zn, thiodicarb, carbofuran, carbofuran + zn e carbosulfan e semeadas em vasos plásticos. Nas plantas, foram confinadas cigarrinhas sadias e avaliada a eficiência desses inseticidas no controle desse inseto, em diferentes intervalos de tempo e em períodos sucessivos. Os produtos imidacloprid e thiamethoxan foram os mais eficientes no controle da cigarrinha, proporcionando eficiência de controle de adultos de D. maidis igual ou superior a 70%, até o trigésimo dia de avaliação, após 4 a 24h de confinamento das cigarrinhas.This research was aimed at checking the efficiency of insecticide seed treatment on corn leafhopper control, at greenhouse. Maize seeds were treated with insecticides (imidacloprid, thiamethoxan, thiodicarb + zn, thiodicarb, carbofuran, carbofuran + zn and carbosulfan and sowed on plastic pots. On those plants healthy leafhoppers were confined, and the efficiency of those insecticides on its control was evaluated, at different intervals of time and in successive periods. The insecticides imidacloprid and thiamethoxan were the most efficient to control the corn leafhoppers, and provided control efficiency of D. maidis adults equal or upper 70% until the thirtieth day of evaluation, after 4 to 24h of leafhoppers confining.

  15. Experimental atomic physics

    International Nuclear Information System (INIS)

    Anon.

    1985-01-01

    The experimental atomic physics program within the physics division is carried out by two groups, whose reports are given in this section. Work of the accelerator atomic physics group is centered around the 6.5-MV EN tandem accelerator; consequently, most of its research is concerned with atomic processes occurring to, or initiated by, few MeV/amu heavy ions. Other activities of this group include higher energy experiments at the Holifield Heavy Ion Research Facility (HHIRF), studies of electron and positron channeling radiation, and collaborative experiments at other institutions. The second experimental group concerns itself with lower energy atomic collision physics in support of the Fusion Energy Program. During the past year, the new Electron Cyclotron Resonance Source has been completed and some of the first data from this facility is presented. In addition to these two activities in experimental atomic physics, other chapters of this report describe progress in theoretical atomic physics, experimental plasma diagnostic development, and atomic data center compilation activities

  16. Eficiência energética de um trator agrícola utilizando duas configurações de tomada de potência

    Directory of Open Access Journals (Sweden)

    Ulisses Giacomini Frantz

    2014-07-01

    Full Text Available A tomada de potência (TDP de um trator agrícola tem por principal finalidade transmitir a potência gerada no motor, para acionamento de órgãos ativos das máquinas agrícolas. Tendo em vista a necessidade de se aumentar a eficiência energética na agricultura, alguns fabricantes disponibilizam para os agricultores uma configuração de TDP que proporciona o acionamento dessas máquinas a um regime de rotação menor do motor do trator. Assim, a rotação da TDP é mantida podendo-se obter uma redução do consumo de combustível. Este trabalho objetivou quantificar o consumo de combustível de um trator agrícola, operando com duas configurações de TDP (normal e econômica em duas áreas agrícolas de relevo distinto. Como resultado, evidencia-se que, com a utilização da TDP econômica, tanto o consumo horário quanto o consumo operacional de combustível, em ambas as áreas trabalhadas, foi menor quando comparado à TDP normal.

  17. Medindo Eficiência de Custos no Setor de Distribuição de Energia Elétrica Brasileiro

    Directory of Open Access Journals (Sweden)

    Wagner Montoro Júnior

    2004-01-01

    Full Text Available O presente trabalho tem o objetivo de verificar a aplicabilidade de métodos paramétricos, que meçam a eficiência de custos de empresas de distribuição de energia elétrica no Brasil. Estimamos funções de custos totais, derivadas a partir de uma função de produção COBB DOUGLAS. O modelo de fronteira de custo é estimado usando-se os métodos GLS (Variance Components - Randon effects e Pooled Least Square (Fixed Effects. Estes métodos são aplicados a uma amostra de 25 empresas de distribuição de energia elétrica no Brasil. Os dados consistem em um painel não balanceado sobre um período de 12 anos, de 1990 até 2001. Os resultados encontrados indicam que no período temporal adotado, todas as empresas são igualmente eficientes no controle de seus custos.

  18. Eficiência de métodos de melhoramento para teor de fibra e produtividade de grãos em progênies de feijoeiro comum

    Directory of Open Access Journals (Sweden)

    Adélia Cristina Fernandes Silva

    2013-01-01

    Full Text Available O objetivo deste estudo foi comparar métodos de melhoramento quanto à variabilidade genética e à eficiência na obtenção de progênies superiores para teor de fibra bruta e produtividade de grãos em feijoeiro comum. As progênies foram obtidas do cruzamento, em 2003, entre as linhagens carioca CNFC 7812 e CNFC 7829. A população segregante foi conduzida por bulk, bulk dentro de F2 e SSD até geração F7. Em 2008 foram amostradas aleatoriamente 64 progênies de cada método para avaliação em Goiás e Paraná. Foram obtidas as estimativas dos componentes de variância, parâmetros genéticos e fenotípicos, média e índices de geração de progênies superiores. As progênies obtidas pelos métodos de bulk e SSD apresentaram diferenças significativas para produtividade e teor de fibra bruta e maior variância genética. O bulk dentro de F2 apresentou os maiores índices de geração de progênies superiores e maiores médias para os dois caracteres, sendo recomendado para os programas de melhoramento de feijoeiro comum.

  19. Atomic mass spectrometry

    International Nuclear Information System (INIS)

    Sanz-Medel, A.

    1997-01-01

    The elemental inorganic analysis seems to be dominated today by techniques based on atomic spectrometry. After an evaluation of advantages and limitations of using mass analysers (ion detectors) versus conventional photomultipliers (photon detector) a brief review of the more popular techniques of the emerging Atomic Mass spectrometry is carried out. Their huge potential for inorganic trace analysis is such that in the future we could well witness how this end of the century and millennium marked the fall of the photons empire in Analytical Atomic Spectrometry. (Author)

  20. 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.

  1. Atom trap trace analysis

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-05-25

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

  2. Division of atomic physics

    International Nuclear Information System (INIS)

    Kroell, S.

    1994-01-01

    The Division of Atomic Physics, Lund Institute of Technology (LTH), is responsible for the basic physics teaching in all subjects at LTH and for specialized teaching in Optics, Atomic Physics, Atomic and Molecular Spectroscopy and Laser Physics. The Division has research activities in basic and applied optical spectroscopy, to a large extent based on lasers. It is also part of the Physics Department, Lund University, where it forms one of eight divisions. Since the beginning of 1980 the research activities of our division have been centred around the use of lasers. The activities during the period 1991-1992 is described in this progress reports

  3. Atom trap trace analysis

    International Nuclear Information System (INIS)

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

    2000-01-01

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

  4. Parametric resonance and cooling on an atom chip

    International Nuclear Information System (INIS)

    Yan Bo; Li Xiaolin; Ke Min; Wang Yuzhu

    2008-01-01

    This paper observes the parametric excitation on atom chip by measuring the trap loss when applying a parametric modulation. By modulating the current in chip wires, it modulates not only the trap frequency but also the trap position. It shows that the strongest resonance occurs when the modulation frequency equals to the trap frequency. The resonance amplitude increases exponentially with modulation depth. Because the Z-trap is an anharmonic trap, there exists energy selective excitation which would cause parametric cooling. We confirm this effect by observing the temperature of atom cloud dropping

  5. Section of Atomic Collisions

    International Nuclear Information System (INIS)

    Berenyi, D.; Biri, S.; Gulyas, L.; Juhasz, Z.; Kover, A.; Orban, A.; Palinkas, J.; Papp, T.; Racz, R.; Ricz, S.

    2009-01-01

    The Section of Atomic Collisions is a research unit with extended activity in the field of atomic and molecular physics. Starting from the study of atomic processes at the beamlines of nuclear physics accelerators in the seventies, our research community became one of the centers of fundamental research in Atomki. We also have a strong connection to materials sciences especially along the line of electron and ion spectroscopy methods. Our present activity covers a wide range of topics from atomic collision mechanisms of fundamental interest, to the complex interactions of electrons, ions, photons and antiparticles with atoms, molecules, surfaces, and specific nanostructures. In the last few years, an increasing fraction of our present topics has become relevant for applications, e.g., molecular collision studies for the radiation therapy methods of tumors, or ion-nanostructure interactions for the future construction of small ion-focusing elements. Our section belongs to the Division of Atomic Physics. The other unit of the Division is the Section of Electron Spectroscopy and Materials Sciences. There are traditionally good connections and a strong collaboration between the groups of the two sections in many fields. From the very beginning of our research work in atomic collisions, external collaborations were of vital importance for us. We regularly organize international workshops in the field of fast ion-atom collisions and related small conferences in Debrecen from 1981. Recently, we organized the Conference on Radiation Damage in Biomolecular Systems (RADAM 2008, Debrecen), and coorganized the Conference on Elementary Processes in Atomic Systems (CEPAS 2008, Cluj). We have access to several large scale facilities in Europe within the framework of formal and informal collaborations. The next themes are in this article: Forward electron emission from energetic atomic collisions; Positron-atom collisions; Photon-atom interactions; Interference effects in electron

  6. High-frequency conductivity of photoionized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Anakhov, M. V.; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru [National Research Nuclear University “MEPhI,” (Russian Federation)

    2016-08-15

    The tensor of the high-frequency conductivity of a plasma created via tunnel ionization of atoms in the field of linearly or circularly polarized radiation is derived. It is shown that the real part of the conductivity tensor is highly anisotropic. In the case of a toroidal velocity distribution of photoelectrons, the possibility of amplification of a weak high-frequency field polarized at a sufficiently large angle to the anisotropy axis of the initial nonequilibrium distribution is revealed.

  7. Atomic physics precise measurements and ultracold matter

    CERN Document Server

    Inguscio, Massimo

    2013-01-01

    Atomic Physics provides an expert guide to two spectacular new landscapes in physics: precision measurements, which have been revolutionized by the advent of the optical frequency comb, and atomic physics, which has been revolutionized by laser cooling. These advances are not incremental but transformative: they have generated a consilience between atomic and many-body physics, precipitated an explosion of scientific and technological applications, opened new areas of research, and attracted a brilliant generation of younger scientists. The research is advancing so rapidly, the barrage of applications is so dazzling, that students can be bewildered. For both students and experienced scientists, this book provides an invaluable description of basic principles, experimental methods, and scientific applications.

  8. History of early atomic clocks

    International Nuclear Information System (INIS)

    Ramsey, N.F.

    2005-01-01

    This review of the history of early atomic clocks includes early atomic beam magnetic resonance, methods of separated and successive oscillatory fields, microwave absorption, optical pumping and atomic masers. (author)

  9. Atomic Energy Authority Bill

    International Nuclear Information System (INIS)

    Gray, J.H.N.; Stoddart, D.L.; Sinclair, R.M.; Ezra, D.

    1985-01-01

    The House, in Committee, discussed the following matters in relation to the Atomic Energy Authority Bill; financing; trading; personnel conditions of employment; public relations; organization; research programmes; fuels; energy sources; information dissemination. (U.K.)

  10. Atomic and Molecular Interactions

    International Nuclear Information System (INIS)

    2002-01-01

    The Gordon Research Conference (GRC) on Atomic and 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

  11. Zeeman atomic absorption spectrometry

    International Nuclear Information System (INIS)

    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

  12. Optics With Cold Atoms

    National Research Council Canada - National Science Library

    Hau, Lene

    2004-01-01

    .... And to test the novel atom sensor, we have built a moving-molasses magneto-optical trap in a geometry tailor-suited to the nanotube detector geometry, involving construction of a highly stable laser...

  13. Atomic Energy Control Regulations

    International Nuclear Information System (INIS)

    1992-01-01

    This is the consolidated text of the Atomic Energy Control Regulations of 17 March 1960, with amendments to 27 August 1992. The Regulations cover the licensing of nuclear facilities, radiation sources, including uranium mining, radiation protection questions, etc. (NEA)

  14. The atomic conflict

    International Nuclear Information System (INIS)

    Mez, L.

    1981-01-01

    This book provides a general view at the atomic programmes of several countries and makes an attempt to unmask the atomic industrial combines with their interlockings. The governments role is analysed as well as the atomic policy of the parties, union-trades and associations. Then, the anti-atomic movements in those countries, their forms of resistance, the resonance and the alternative proposals are presented. The countries concerned are Australia, the FRG, COMECON, Danmark, the EG, Finland, France, Great Britain, Ireland, Japan, the Netherlands, Norway, Austria, Sweden, Switzerland, Spain and the USA. For the pocket book version, Lutz Mez adds an updating epilogue which continues with the developments until springtime 1981. (orig./HP) [de

  15. 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.

  16. Atom chip gravimeter

    Science.gov (United States)

    Schubert, Christian; Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Ahlers, Holger; Müntinga, Hauke; Matthias, Jonas; Sahelgozin, Maral; Herr, Waldemar; Lämmerzahl, Claus; Ertmer, Wolfgang; Rasel, Ernst

    2016-04-01

    Atom interferometry has developed into a tool for measuring rotations [1], accelerations [2], and testing fundamental physics [3]. Gravimeters based on laser cooled atoms demonstrated residual uncertainties of few microgal [2,4] and were simplified for field applications [5]. Atomic gravimeters rely on the interference of matter waves which are coherently manipulated by laser light fields. The latter can be interpreted as rulers to which the position of the atoms is compared. At three points in time separated by a free evolution, the light fields are pulsed onto the atoms. First, a coherent superposition of two momentum states is produced, then the momentum is inverted, and finally the two trajectories are recombined. Depending on the acceleration the atoms experienced, the number of atoms detected in the output ports will change. Consequently, the acceleration can be determined from the output signal. The laser cooled atoms with microkelvin temperatures used in state-of-the-art gravimeters impose limits on the accuracy [4]. Therefore, ultra-cold atoms generated by Bose-Einstein condensation and delta-kick collimation [6,7] are expected to be the key for further improvements. These sources suffered from a low flux implying an incompatible noise floor, but a competitive performance was demonstrated recently with atom chips [8]. In the compact and robust setup constructed for operation in the drop tower [6] we demonstrated all steps necessary for an atom chip gravimeter with Bose-Einstein condensates in a ground based operation. We will discuss the principle of operation, the current performance, and the perspectives to supersede the state of the art. The authors thank the QUANTUS cooperation for contributions to the drop tower project in the earlier stages. This work is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry for Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under grant numbers DLR 50WM

  17. Atoms at work

    International Nuclear Information System (INIS)

    1982-07-01

    This illustrated booklet discusses the following: atoms; fission of uranium; nuclear power plants; reactor types; plutonium (formation, properties, uses); radioactive waste (fuel cycle, reprocessing, waste management); nuclear fusion; fusion reactors; radiation; radioisotopes and their uses. (U.K.)

  18. 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...

  19. Atomic Interferometry, Phase I

    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...

  20. Atomic bomb cataracts

    International Nuclear Information System (INIS)

    Shiraeda, Kanji

    1992-01-01

    Eye disturbance caused by atomic bomb radiation can be divided into three groups: direct injury immediately after exposure, eye lesions associated with radiation syndrome, and delayed disturbance. The crystalline lens of the eye is the most radiosensitive. Atomic bomb cataract has been investigated in a number of studies. The first section of this chapter discusses radiation cataract in terms of the incidence and characteristics. The second section deals with atomic bomb cataract, which can be diagnosed based on the four criteria: (1) opacity of the crystalline lens, (2) a history of proximal exposure, (3) lack of eye disease complicating cataract, and (4) non-exposure to radiation other than atomic bombing. The prevalence of cataract and severity of opacity are found to correlate with exposure doses and age at the time of exposure. Furthermore, it is found to correlate with distance from the hypocenter, the condition of shielding, epilation, and the presence or absence or degree of radiation syndrome. (N.K.)

  1. Femtosecond photoionization of atoms under noise

    International Nuclear Information System (INIS)

    Singh, Kamal P.; Rost, Jan M.

    2007-01-01

    We investigate the effect of incoherent perturbations on atomic photoionization due to a femtosecond midinfrared laser pulse by solving the time-dependent stochastic Schroedinger equation. For a weak laser pulse which causes almost no ionization, an addition of a Gaussian white noise to the pulse leads to a significantly enhanced ionization probability. Tuning the noise level, a stochastic resonancelike curve is observed showing the existence of an optimum noise for a given laser pulse. Besides studying the sensitivity of the obtained enhancement curve on the pulse parameters, such as the pulse duration and peak amplitude, we suggest that experimentally realizable broadband chaotic light can also be used instead of the white noise to observe similar features. The underlying enhancement mechanism is analyzed in the frequency domain by computing a frequency-resolved atomic gain profile, as well as in the time domain by controlling the relative delay between the action of the laser pulse and noise

  2. Influence of the virtual photon field on the squeezing properties of an atom laser

    International Nuclear Information System (INIS)

    Jian-Gang, Zhao; Chang-Yong, Sun; Ling-Hua, Wen; Bao-Long, Liang

    2009-01-01

    This paper investigates the squeezing properties of an atom laser without rotating-wave approximation in the system of a binomial states field interacting with a two-level atomic Bose–Einstein condensate. It discusses the influences of atomic eigenfrequency, the interaction intensity between the optical field and atoms, parameter of the binomial states field and virtual photon field on the squeezing properties. The results show that two quadrature components of an atom laser can be squeezed periodically. The duration and the degree of squeezing an atom laser have something to do with the atomic eigenfrequency and the parameter of the binomial states field, respectively. The collapse and revival frequency of atom laser fluctuation depends on the interaction intensity between the optical field and atoms. The effect of the virtual photon field deepens the depth of squeezing an atom laser

  3. The Atomic Energy Control Board

    International Nuclear Information System (INIS)

    Doern, G.B.

    1976-01-01

    This study describes and assesses the regulatory and administrative processes and procedures of the Atomic Energy Control Board, the AECB. The Atomic Energy Control Act authorized the AECB to control atomic energy materials and equipment in the national interest and to participate in measures for the international control of atomic energy. The AECB is authorized to make regulations to control atomic energy materials and equipment and to make grants in support of atomic energy research. (author)

  4. Energy flux of hot atoms

    International Nuclear Information System (INIS)

    Wotzak, G.P.; Kostin, M.D.

    1976-01-01

    The process in which hot atoms collide with thermal atoms of a gas, transfer kinetic energy to them, and produce additional hot atoms is investigated. A stochastic method is used to obtain numerical results for the spatial and time dependent energy flux of hot atoms in a gas. The results indicate that in hot atom systems a front followed by an intense energy flux of hot atoms may develop

  5. Harnessing the atom

    International Nuclear Information System (INIS)

    1999-01-01

    Splitting the atom has had a major impact on the history of the latter part of the 20th century. This film depicts the many benefits - and also drawbacks - of nuclear technology, and describes how the International Atomic Energy Agency performs its various tasks. It touches on challenges such as the choice between major energy sources, growing concerns about the global climate, and prospects for nuclear arms control and disarmament

  6. Atomic Energy Act 1946

    International Nuclear Information System (INIS)

    1946-01-01

    This Act provides for the development of atomic energy in the United Kingdom and for its control. It details the duties and powers of the competent Minister, in particular his powers to obtain information on and to inspect materials, plant and processes, to control production and use of atomic energy and publication of information thereon. Also specified is the power to search for and work minerals and to acquire property. (NEA) [fr

  7. 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.

  8. Manipulating atoms with photons

    International Nuclear Information System (INIS)

    Cohen-Tannoudji, C.N.

    1998-01-01

    The article is a translation of the lecture delivered on the occasion of the 1997 Nobel Prize awarding ceremony. The physical mechanisms which allow manipulating of neutral atoms with laser photons are described. A remark is also made concerning several possible applications of ultra-cool atoms and streams of future research. The article is completed by Prof. Cohen-Tannoudji's autobiography. (Z.J.)

  9. 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.

  10. Acaricides efficiency on Rhipicephalus (Boophilus microplus from Bahia state North-Central region Eficiência de acaricidas sobreRhipicephalus (Boophilus microplusna região Centro-Norte, Bahia

    Directory of Open Access Journals (Sweden)

    José Tadeu Raynal

    Full Text Available The cattle tick Rhipicephalus (Boophilus microplus is responsible for major losses in the Brazilian livestock, mainly due to reduction in cattle productive performance. Resistance development to major classes of acaricide widely used nowadays has been extensively reported, as well as the occurrence of residues from these compounds in animal products and the environment. This study aimed to evaluate the efficiency of acaricides on R. (B. microplus collected from rural properties in the North-Central region of Bahia State. Ticks were collected in several cattle farms in the cited region, and an in vitro acaricide efficiency assay was performed based on the immersion of ticks in acaricide solutions made according to manufacturers' recommendations. The results obtained in the experiments indicated varying degrees of efficiency of the several bases studied, with the products benzofenilurea, macrocyclic lactone and fipronil showing the highest levels of efficiency, 100%, 100% and 97.34%, respectively. It was possible to conclude that, for the region studied, there are different degrees of commercial acaricides efficiency, and many present less than 95% effectiveness, value determined as acceptable by the Brazilian legislation.O carrapato Rhipicephalus (Boophilus microplus é responsável por grandes perdas na pecuária brasileira, principalmente devido à redução no desempenho produtivo dos animais. A resistência do parasita a diferentes classes de acaricidas tem sido amplamente relatada, bem como os problemas de ocorrência de resíduos desses compostos em produtos de origem animal e no ambiente. Esse estudo teve como objetivo avaliar a eficiência de diversos acaricidas sobre populações de R. (B. microplus provenientes de propriedades rurais da Região Centro-Norte do Estado da Bahia, Brasil. Teleóginas ingurgitadas foram colhidas em diferentes propriedades da região e submetidas a ensaio in vitro de eficiência de acaricidas, baseado na

  11. 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).

  12. On the bosonic atoms

    Science.gov (United States)

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

    2018-01-01

    We investigate ground state properties of atoms, in which substitute fermions - electrons by bosons, namely π --mesons. We perform some calculations in the frame of modified Hartree-Fock (HF) equation. The modification takes into account symmetry, instead of anti-symmetry of the pair identical bosons wave function. The modified HF approach thus enhances (doubles) the effect of self-action for the boson case. Therefore, we accordingly modify the HF equations by eliminating the self-action terms "by hand". The contribution of meson-meson and meson-nucleon non-Coulomb interaction is inessential at least for atoms with low and intermediate nuclear charge, which is our main subject. We found that the binding energy of pion negative ions A π - , pion atoms A π , and the number of extra bound pions ΔN π increases with the growth of nuclear charge Z. For e.g. Xe ΔN π = 4. As an example of a simple process with a pion atom, we consider photoionization that differs essentially from that for electron atoms. Namely, it is not monotonic decreasing from the threshold but has instead a prominent maximum above threshold. We study also elastic scattering of pions by pion atoms.

  13. Electron - atom bremsstrahlung

    International Nuclear Information System (INIS)

    Kim, L.

    1986-01-01

    Features of bremsstrahlung radiation from neutral atoms and atoms in hot dense plasmas are studied. Predictions for the distributions of electron-atom bremsstrahlung radiation for both the point-Coulomb potential and screened potentials are obtained using a classical numerical method. Results agree with exact quantum-mechanical partial-wave results for low incident electron energies in both the point-Coulomb and screened potentials. In the screened potential, the asymmetry parameter of a spectrum is reduced from the Coulomb values. The difference increases with decreasing energy and begins to oscillate at very low energies. The scaling properties of bremsstrahlung spectra and energy losses were also studied. It was found that the ratio of the radiative energy loss for positrons to that for electrons obeys a simple scaling law, being expressible fairly accurately as a function only of the quantity T 1 /Z 2 . This scaling is exact in the case of the point-Coulomb potential, both for classical bremsstrahlung and for the nonrelativistic dipole Sommerfeld formula. Bremsstrahlung from atoms in hot dense plasmas were also studied describing the atomic potentials by the temperature-and-density dependent Thomas-Fermi mode. Gaunt factors were obtained with the relativistic partial-wave method for atoms in plasmas of various densities and temperatures

  14. FAO and atomic energy

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1960-07-15

    During the past six years FAO has become more engaged in work concerned with atomic energy. In 1957 it established an Atomic Energy Branch. The new forces and new tools which have become available for use in the fight against poverty, disease and malnutrition can be of the greatest assistance in FAO's work in nearly all phases of the production, storage and distribution of food and other agricultural products. The Organization promotes their use to improve the standards of feeding, clothing and housing throughout the world. Another side of work related to atomic energy is concerned with combating contamination from the use of atomic energy for power production and other purposes. This raises considerable problems for food and agriculture, so that FAO also has a responsibility for assisting Governments in safeguarding their food and food-producing resources from contamination. FAO is essentially concerned with fostering wider knowledge of the many contributions that atomic science can make to agriculture, forestry, fisheries and nutrition. It is also concerned in assisting governments to establish sound programmes for applying atomic science in food and agriculture. One way of spreading such knowledge is through the publication of documents and reports

  15. FAO and atomic energy

    International Nuclear Information System (INIS)

    1960-01-01

    During the past six years FAO has become more engaged in work concerned with atomic energy. In 1957 it established an Atomic Energy Branch. The new forces and new tools which have become available for use in the fight against poverty, disease and malnutrition can be of the greatest assistance in FAO's work in nearly all phases of the production, storage and distribution of food and other agricultural products. The Organization promotes their use to improve the standards of feeding, clothing and housing throughout the world. Another side of work related to atomic energy is concerned with combating contamination from the use of atomic energy for power production and other purposes. This raises considerable problems for food and agriculture, so that FAO also has a responsibility for assisting Governments in safeguarding their food and food-producing resources from contamination. FAO is essentially concerned with fostering wider knowledge of the many contributions that atomic science can make to agriculture, forestry, fisheries and nutrition. It is also concerned in assisting governments to establish sound programmes for applying atomic science in food and agriculture. One way of spreading such knowledge is through the publication of documents and reports

  16. Atomic bomb and leukemia

    International Nuclear Information System (INIS)

    Ichimaru, M.; Tomonaga, M.; Amenomori, T.; Matsuo, T.

    1991-01-01

    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∼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)

  17. Optical lattice clock with Strontium atoms

    International Nuclear Information System (INIS)

    Baillard, X.

    2008-01-01

    This thesis presents the latest achievements regarding the optical lattice clock with Strontium atoms developed at LNE-SYRTE. After a review of the different types of optical clocks that are currently under development, we stress on the concept of optical lattice clock which was first imagined for Sr 87 using the 1 S 0 → 3 P 0 transition. We exhibit the features of this atom, in particular the concept of magic wavelength for the trap, and the achievable performances for this kind of clock. The second part presents the experimental aspects, insisting particularly on the ultra-stable laser used for the interrogation of the atoms which is a central part of the experiment. Among the latest improvements, an optical pumping phase and an interrogation phase using a magnetic field have been added in order to refine the evaluation of the Zeeman effect. Finally, the last part presents the experimental results. The last evaluation of the clock using Sr 87 atoms allowed us to reach a frequency accuracy of 2.6*10 -15 and a measurement in agreement with the one made at JILA (Tokyo university) at the 10 -15 level. On another hand, thanks to recent theoretical proposals, we made a measurement using the bosonic isotope Sr 88 by adapting the experimental setup. This measurement represents the first evaluation for this type of clock, with a frequency accuracy of 7*10 -14 . (author)

  18. Atomic phenomena in dense plasmas

    International Nuclear Information System (INIS)

    Weisheit, J.C.

    1981-03-01

    The following chapters are included: (1) the plasma environment, (2) perturbations of atomic structure, (3) perturbations of atomic collisions, (4) formation of spectral lines, and (5) dielectronic recombination

  19. Resonant Laser Manipulation of an Atomic Beam

    Science.gov (United States)

    2010-07-01

    Technical Paper 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Resonant Laser Manipulation of an Atomic Beam...steering and collimating flows with higher densities and energies than current common practice . One impediment to this extension is the development of...where Δεg is the ground state Stark shift, Ω is the Rabi frequency (related to intensity), Isat is the saturation intensity of the transition, and I(r

  20. Quantum localization of the kicked rydberg atom

    Science.gov (United States)

    Yoshida; Reinhold; Burgdorfer

    2000-03-20

    We investigate the quantum localization of the one-dimensional Rydberg atom subject to a unidirectional periodic train of impulses. For high frequencies of the train the classical system becomes chaotic and leads to fast ionization. By contrast, the quantum system is found to be remarkably stable. We find this quantum localization to be directly related to the existence of "scars" of the unstable periodic orbits of the system. The localization length is given by the energy excursion along the periodic orbits.

  1. Dispersive detection of radio-frequency-dressed states

    Science.gov (United States)

    Jammi, Sindhu; Pyragius, Tadas; Bason, Mark G.; Florez, Hans Marin; Fernholz, Thomas

    2018-04-01

    We introduce a method to dispersively detect alkali-metal atoms in radio-frequency-dressed states. In particular, we use dressed detection to measure populations and population differences of atoms prepared in their clock states. Linear birefringence of the atomic medium enables atom number detection via polarization homodyning, a form of common path interferometry. In order to achieve low technical noise levels, we perform optical sideband detection after adiabatic transformation of bare states into dressed states. The balanced homodyne signal then oscillates independently of field fluctuations at twice the dressing frequency, thus allowing for robust, phase-locked detection that circumvents low-frequency noise. Using probe pulses of two optical frequencies, we can detect both clock states simultaneously and obtain population difference as well as the total atom number. The scheme also allows for difference measurements by direct subtraction of the homodyne signals at the balanced detector, which should technically enable quantum noise limited measurements with prospects for the preparation of spin squeezed states. The method extends to other Zeeman sublevels and can be employed in a range of atomic clock schemes, atom interferometers, and other experiments using dressed atoms.

  2. Multimode quantum model of a cw atom laser

    International Nuclear Information System (INIS)

    Hope, J.J.; Haine, S.A.; Savage, C.M.

    2002-01-01

    Full text: Laser cooling allows dilute atomic gases to be cooled to within K of absolute zero. Ultracold gases were first achieved twenty years ago and have since found applications in areas such as spectroscopy, time standards, frequency standards, quantum information processing and atom optics. The atomic analogue of the lasing mode in optical lasers is Bose-Einstein Condensation (BEC), in which a cooled sample of atoms condense into the lowest energy quantum state. This new state of matter was recently achieved in dilute Bose gases in 1995. Atoms coupled out of a BEC exhibit long-range spatial coherence, and provide the coldest atomic source currently available. These atomic sources are called 'atom lasers' because the BEC is analogous to the lasing mode of an optical laser. The high spectral flux from optical lasers is caused by a process called gain-narrowing, which requires continuous wave (cw) operation. Coupling a BEC quickly into an untrapped state forms a coherent atomic beam but it has a spread in momentum as large as the trapped BEC. Coupling the atoms out more slowly reduces the output linewidth at the expense of reducing the overall flux. These atom lasers are equivalent to Q-switched optical lasers. A cw atom laser with gain-narrowing would produce an increasingly monoenergetic output as the flux increased, dramatically improving the spectral flux. A cw atom laser is therefore a major goal of the atom optics community, but there are several theoretical and practical obstacles to understanding the complexities of such a system. The main obstacle to the production of a cw atom laser is the technical difficulties involved in continuously pumping the lasing mode. No complete theory exists which describes a cw atom laser. Complete cw atom laser models require a quantum field description due to their non-Markovian dynamics, significant spatial effects and the dependence of the output on the quantum statistics of the lasing mode. The extreme dimensionality

  3. 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...

  4. An Atomic Gravitational Wave Interferometric Sensor (AGIS)

    Energy Technology Data Exchange (ETDEWEB)

    Dimopoulos, Savas; /Stanford U., Phys. Dept.; Graham, Peter W.; /SLAC; Hogan, Jason M.; Kasevich, Mark A.; /Stanford U., Phys. Dept.; Rajendran, Surjeet; /SLAC /Stanford U., Phys. Dept.

    2008-08-01

    We propose two distinct atom interferometer gravitational wave detectors, one terrestrial and another satellite-based, utilizing the core technology of the Stanford 10m atom interferometer presently under construction. Each configuration compares two widely separated atom interferometers run using common lasers. The signal scales with the distance between the interferometers, which can be large since only the light travels over this distance, not the atoms. The terrestrial experiment with baseline {approx} 1 km can operate with strain sensitivity {approx} 10{sup -19}/{radical}Hz in the 1 Hz-10 Hz band, inaccessible to LIGO, and can detect gravitational waves from solar mass binaries out to megaparsec distances. The satellite experiment with baseline {approx} 1000 km can probe the same frequency spectrum as LISA with comparable strain sensitivity {approx} 10{sup -20}/{radical}Hz. The use of ballistic atoms (instead of mirrors) as inertial test masses improves systematics coming from vibrations, acceleration noise, and significantly reduces spacecraft control requirements. We analyze the backgrounds in this configuration and discuss methods for controlling them to the required levels.

  5. Thermal 18F atom addition to olefins

    International Nuclear Information System (INIS)

    Rogers, P.J.M.

    1986-01-01

    The addition of thermal 18 F atoms to olefins was investigated using various substrate molecules. The 18 F atoms were produced by the 19 F(n,2n) 18 F nuclear reaction with >10 5 eV of energy which is removed by multiple collisions with SF 6 molecules before reaction occurs with an olefin. By varying the SF 6 /substrate mole ratio it was demonstrated that the fraction of non-thermal reactions is dependent upon the frequency of non-reactive energy reducing collisions with SF 6 . The rate constants for addition and abstraction reactions with propene, cis-1-chloropropene and trans-1-chloropropene were determined. The substitution of a C1 atom for the olefinic H atom in the C 1 position does not affect the rate of 18 F bond formation but it changes the orientation of attack. The 18 F atom prefers the terminal carbon-in propene and propene-d 6 by a factor of 1.35 while the preference is less than 0.5 for the terminal carbon in cis-1-chloropropene and trans-1-chloropropene. The addition of 18 F atoms to olefins creates vibrationally excited fluoroalkyl radicals which can either decompose or stabilize by collision with another molecule. The rate constants for decomposition of excited CH 3 CHCHC1F radicals formed by 18 F addition to cis-1-chloropropene and trans-1-chloropropene are competitive with C 1 -C 2 bond rotation. The 18 F atoms add to the parent molecule with retention of geometry and a memory of the geometry persists as demonstrated by the cis-1-fluoropropene/trans-1-fluoropropene decomposition product ratio

  6. Eficiência do uso da água na produção do pinhão-manso no semiárido nordestino

    Directory of Open Access Journals (Sweden)

    Clayton Moura de Carvalho

    2015-06-01

    Full Text Available O governo do estado do Ceará tem buscado, sem muito sucesso, revitalizar a cultura do algodão, entretanto, os seus elevados custos fitossanitários têm impedido a permanência da área cultivada. Um das alternativas viáveis para a ocupação de espaços provenientes da ausência do algodão é o cultivo do pinhão manso visando à produção do biodiesel. Face ao exposto, este trabalho objetivou avaliar os efeitos de diferentes níveis de lâminas de água e adubação nitrogenada no uso eficiente da água na produção de frutos, sementes e albúmen do pinhão manso. O trabalho foi desenvolvido na área experimental da Fazenda Bandeira pertencente à Agroempresa Brasil Ecodiesel, situada em Crateús – CE, localizada em 05˚23’25’’S, 40˚57’38’’W e 717 m de altitude. O delineamento experimental adotado foi o de blocos ao acaso no esquema de parcelas subdivididas. Os tratamentos foram compostos a partir da combinação de cinco lâminas de água (50%, 75%, 100%, 125% e 150% da evaporação do Tanque Classe “A”, e quatro níveis de adubação nitrogenada (N1 = 0 kg ha-1 de N; N2 = 25 kg ha-1 de N; N3 = 50 kg ha-1 de N; N4 = 75 kg ha-1 de N, com três repetições. As variáveis analisadas foram a eficiência do uso da água na produção de frutos, sementes e albúmen. Os maiores valores da eficiência do uso da água na produção de frutos, sementes e albúmen foram encontrados com a menor lâmina aplicada. Como o semiárido cearense apresenta naturalmente condições de escassez hídrica torna-se viável o cultivo do pinhão manso com a lâmina de 735 mm, representando uma economia de água de 124% em relação à maior lâmina aplicada. No que se refere às doses de adubação, as dosagens utilizadas neste experimento não influenciaram nos resultados das variáveis estudadas.

  7. Desigualdade de renda e eficiência técnica na geração de bem-estar entre os estados brasileiros

    Directory of Open Access Journals (Sweden)

    Emerson Marinho

    2004-12-01

    Full Text Available Este artigo estima as medidas de eficiência técnica dos estados brasileiros na geração de bem-estar, entre os anos de 1986 e 1998, utilizando o método não-paramétrico Data Envelopment Analisys (DEA. São utilizadas como medidas de bem-estar a medida de Sen e, alternativamente, o PIB per capita e o Índice de Desenvolvimento Humano (IDH. Adicionalmente, são calculadas as medidas de desigualdade de renda inter/intra-regional de Theil para se analisar a trajetória da desigualdade no Brasil como uma determinante do bem-estar. Comparando as medidas de desigualdade no início e no final do período, nota-se que apenas nas regiões nordeste e sudeste ocorreram reduções significativas da desigualdade e que as medidas de desigualdade totais não sofreram qualquer modificação significativa durante o período analisado. Quanto às medidas de eficiência na geração de bem-estar, o modelo utilizando a medida de bem-estar de Sen aponta os estados de São Paulo, Rio Grande do Sul, Amazonas, Roraima e Amapá como sendo os mais eficientes na geração de bem-estar. O modelo com PIB per capita, replica basicamente os resultados anteriores. Finalmente, utilizando o IDH, os estados acima citados, mantém-se ainda como os mais eficientes com exceção do estado de São PauloIn this paper we utilize the Data Envelopment Analysis (DEA, a non-parametric method, to estimate measures of technical efficiency of the Brazilian states in the generation of welfare between 1986 and 1998. The basic welfare measures considered include the measure developed by Sen and, alternatively, GDP per capita and the Human Development Index (HDI. Additionally, Theil's inter and intra-regional income inequality measures are calculated so that the path of income inequality as a determinant of welfare could also be analyzed for Brazil. Comparing these inequality measures in the beginning and in the end of the period in analysis, we note that only in the Northeast and in the

  8. Mercados futuro e à vista de açúcar: uma análise empírica de eficiência versus arbitragem

    Directory of Open Access Journals (Sweden)

    Roseli da Silva

    2010-06-01

    Full Text Available Este trabalho testa a hipótese de eficiência relativa dos mercados futuro e à vista (spot de açúcar, para dois horizontes de previsão, em contraposição à hipótese de arbitragem de commodities. Utiliza-se o modelo de não-arbitragem de Brenner e Kroner (1995 e aplica-se a metodologia de testes comparativos proposta por Kellard (2002, que usa a cointegração multivariada com restrição sobre o espaço de cointegração. A base de dados é formada a partir dos futuros do contrato número 11 negociado na Nybot (New York Board of Trade, dos preços no mercado à vista coletados pelo Cepea (Centro de Estudos Avançados em Economia Aplicada e da taxa de juros doméstica, todas em bases diárias (mai/97 a dez/07. A correspondência da amostra é construída de acordo com os vencimentos dos contratos, considerando-se dois períodos de previsão: 28 e 56 dias. Em linhas gerais, as evidências empíricas encontradas suportam a adequação da metodologia de cointegração para análise de eficiência relativa nos mercados de açúcar, em contraposição à hipótese de arbitragem. Além disso, geram evidências fracas de ineficiência, resultados sujeitos à hipótese de estacionariedade do custo de carregamento, exceto pelo componente taxa de juros.This study tests the relative efficiency hypothesis of future and spot sugar markets for two forecast horizons, as opposed to commodity arbitrage. It was used a no-arbitrage model of Brenner and Kroner (1995 and applied the methodology of comparative tests proposed by Kellard (2002, using multivariate cointegration methodology with restrictions on the cointegrated space. The database is formed by future prices of the number 11 contract traded on the Nybot (New York Board of Trade, domestic spot prices collected by Cepea (Center for Advanced Studies in Applied Economics and the domestic interest rate, all on daily basis (May/97 to Dec/07. The matching sample is constructed by the futures contract

  9. Consumo e eficiência do uso da água e componentes do rendimento do arroz irrigado Water use ifficiency, water consumiption and rice yield components

    Directory of Open Access Journals (Sweden)

    Marcos Gregório Ramos Hernandez

    1997-08-01

    Full Text Available Este trabalho teve como objetivo avaliar o efeito de dois níveis de manejo da água, preparo do solo e de herbicidas no rendimento de grãos, consumo de água, eficiência do uso da água e nos componentes do rendimento do arroz irrigado. O experimento foi conduzido no ano agrícola 1993/1994 em área da Universidade Federal de Santa Maria, Santa Maria, RS. A cultivar de arroz BR-IRGA-414 foi semeada em linhas, em 22 de dezembro de 1993. O delineamento experimental foi de blocos ao acaso, trifatorial (2³, constituído de duas épocas do início da irrigação (15 e 30 dias após a emergência - DAE, dois sistemas de preparo do solo (preparo convencional e cultivo mínimo e controle de plantas invasoras (com e sem uso de herbicidas. Os resultados demonstraram que o consumo de água não diferiu significativamente entre os tratamentos. A associação entre o início da irrigação aos 30 DAE e o cultivo mínimo promoveu menor eficiência do uso da água. O inicio da irrigação aos 15 DAE proporcionou maior índice de colheita com maior número de panículas por metro quadrado e também menor esterilidade de espiguetas em relação à irrigação com início aos 30 DAE.The objective of this experiment was to study the effect oftwo water managments, tiliage systems and weed contral on rice yield, water use and water use efficiency and crop yield components. The experiment was conducted in 1993/94 crop growing season in the experimental field ofthe Federal University of Santa Maria, Santa Maria - RS. Rice cultivar BR-IRGA-414 was sowed in rows in December 22, 1993. A factorial (23 experiment in a completely randomized block design was used wiih two irrigation dates (15 and 30 days after emergency - DAE, two soil tillage system (minimum and conventional and two weed control leveis (with and withoul herbicide appiication. The results indicate that the water consumption was similar among ali treatments. The interaction between irrigation at 30 DAE

  10. UNESCO and atomic energy

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1960-01-15

    Atomic energy has been of particular concern to UNESCO virtually since the founding of this United Nations agency with the mission of promoting the advancement of science along with education and culture. UNESCO has been involved in the scientific aspects of nuclear physics - notably prior to the creation of the International Atomic Energy Agency - but it has also focussed its attention upon the educational and cultural problems of the atomic age. UNESCO's sphere of action was laid down by its 1954 General Conference which authorized its Director-General to extend full co-operation to the United Nations in atomic energy matters, with special reference to 'the urgent study of technical questions such as those involved in the effects of radioactivity on life in general, and to the dissemination of objective information concerning all aspects of the peaceful utilization of atomic energy; to study, and if necessary, to propose measures of international scope to facilitate the use of radioisotopes in research and industry'. UNESCO's first action under this resolution was to call a meeting of a committee of experts from twelve nations to study the establishment of a system of standards and regulations for the preparation, distribution, transport and utilization of radioactive isotopes and tracer molecules

  11. Eficiência na remoção de coliformes em águas cinza através da fitorremediação

    Directory of Open Access Journals (Sweden)

    Verena S. Baracuhy

    2015-03-01

    Full Text Available O semiárido é caracterizado pelas irregularidades pluviais e o tratamento de águas cinza para reuso na agricultura com tecnologia ecológica é uma forma de conviver com a seca nessas regiões. Nesse contexto, a pesquisa foi realizada no distrito de Ribeira no município de Cabaceiras/PB objetivando-se avaliar a eficiência da remoção dos coliformes totais e fecais do efluente tratado nas unidades de produção agrícola através da fitorremediação. Foram realizados dois tratamentos com e sem fitorremediação, a cultura utilizada foi o capim roxo. As águas cinza eram provenientes de uma lavanderia pública. Foram coletadas amostras mensais e analisadas os coliformes total e fecal (Escherichia coli. No tratamento sem fitorremediação, os coliformes totais variaram de 1,583 x 103 a 2,0224 x 103 (UFC/100 mL e quando o tratamento tinha o auxílio do capim roxo, ou seja, com fitorremediação os coliformes totais oscilaram de 1,354 x 103 a 2,0224 x 103 (UFC/100 mL. Ocorreu uma redução significativa de Escherichia coli no tratamento com fitorremediação. A utilização da fitorremediação no tratamento de águas cinza reduziu a presença de coliformes totais e fecal, sendo assim uma alternativa viável de tratamento, proporcionando um aumento da qualidade hídrica.

  12. Eficiência agronômica e fisiológica na melancia fertirrigada com diferentes doses de nitrogênio e fósforo

    Directory of Open Access Journals (Sweden)

    Max Venicius Teixeira da Silva

    2014-07-01

    Full Text Available 800x600 -A cultura da melancia, a exemplo de outras oleráceas, tem na nutrição mineral um dos fatores que contribui diretamente na produtividade e na qualidade dos frutos. O trabalho teve como objetivo avaliar a eficiência agronômica e fisiológicas das cultivares Olimpia e Leopard sob diferentes doses de nitrogênio e fósforo via fertirrigação. O delineamento experimental adotado foi em blocos ao acaso com fatorial 4x4, os fatores estudados foram quatro doses combinadas de nitrogênio (N e fósforo (P, sendo, respectivamente: T1(0; 0, T2(48; 88, T3(121; 220 e T4(218; 396; duas cultivares de melancieira e cinco épocas após transplantio (23, 30, 37, 46 e 58 DAT. As doses de N e P equivalem respectivamente a 0%, 40%, 100% e 180% da dose adotada pelos produtores locais do polo agrícola de Mossoró-Baraúna. Tratamento T3 (121 kg ha-1 de N e 218 kg ha-1 de P que corresponde a dose adotada pelos produtores locais da região de Mossoró, foi o que mais incrementou na produtividade de ambas as culturas (Olimpia e Leopard, sendo considerado, agronomicamente, o mais eficiente para alcançar maior produtividade. O tratamento T2 (48 kg ha-1 de N e 88 kg ha-1 de P que corresponde a 40% da dose adotada pelos produtores de Mossoró, foi o que mais incrementou nutrientes na planta (olimpia e Leopard, sendo considerado, fisiologicamente, o mais eficiente para acumular nutrientes na planta. Normal 0 21 false false false PT-BR X-NONE X-NONE Análise da eficiência do mercado futuro brasileiro de boi gordo usando co-integração

    Directory of Open Access Journals (Sweden)

    André Steffens Moraes

    2009-09-01

    Full Text Available A hipótese de que os preços futuros são preditores não viesados dos preços à vista é uma hipótese conjunta de que os mercados são eficientes e que não existe prêmio ao risco. Entretanto, na presença de prêmio ao risco, a hipótese de não viés pode ser rejeitada mesmo quando o mercado é eficiente. Este artigo testa a eficiência do mercado futuro brasileiro do boi gordo na presença de prêmio ao risco, usando técnicas de co-integração. Os resultados mostram que o mercado futuro do boi gordo é eficiente e não viesado no longo prazo, independente da presença de prêmio ao risco.The hypothesis that future prices are unbiased predictors of spot prices is a joint hypothesis that markets are efficient and risk premium are absent. However, the unbiasedness hypothesis may be rejected in the presence of a risk premium, even when the market is efficient. The objective of this article is to test market efficiency for the Brazilian live cattle while permitting the presence of risk premium, using cointegration techniques. Results show that the future markets for live cattle are efficient and unbiasedness in the long run, and does not depend of the presence of a risk premium.

  13. Accelerators for atomic energy research

    International Nuclear Information System (INIS)

    Shibata, Tokushi

    1999-01-01

    The research and educational activities accomplished using accelerators for atomic energy research were studied. The studied items are research subjects, facility operation, the number of master theses and doctor theses on atomic energy research using accelerators and the future role of accelerators in atomic energy research. The strategy for promotion of the accelerator facility for atomic energy research is discussed. (author)

  14. Atomic nucleus and elementary particles

    International Nuclear Information System (INIS)

    Zakrzewski, J.

    1976-01-01

    Negatively charged leptons and hadrons can be incorporated into atomic shells forming exotic atoms. Nucleon resonances and Λ hyperons can be considered as constituents of atomic nuclei. Information derived from studies of such exotic systems enriches our knowledge of both the interactions of elementary particles and of the structure of atomic nuclei. (author)

  15. Development of an atomic clock on an atom chip: Optimisation of the coherence time and preliminary characterisation

    International Nuclear Information System (INIS)

    Lacroute, Clement

    2010-01-01

    We describe the construction and preliminary characterization of an atomic clock on an atom chip. A sample of magnetically trapped 87 Rb atoms is cooled below 1 μK, close to Bose- Einstein condensation temperature. The trapped states |F = 1; m F = -1> and |F = 2;m F = 1> define our two-photon clock transition. Atoms are trapped around a field B0 = 3.23 G, where the clock frequency is first-order insensitive to magnetic field fluctuations. We have designed an atom chip that includes a microwave coplanar waveguide which drives the 6.835 GHz transition. The whole clock cycle is performed in the vicinity of the chip surface, making the physics package compact (5 cm) 3 . We first describe the experimental setup of the clock, and the optical bench that has been developed and characterized during this thesis. We then give the results obtained for atom cooling, which led to obtaining a 3 10 4 atoms Bose-Einstein condensate. We finally present the results obtained by Ramsey spectroscopy of the clock transition. We measure coherence times exceeding 10 seconds with our setup, dominated by atom losses. A preliminary measurement shows that the clock relative frequency stability is of 6 10 -12 at 1 s, limited by technical noise. Our goal is to reach a stability in the low 10 -13 at 1 s, i.e. better than commercial clocks and competitive with today's best compact clocks. (author)

  16. Compilation of data from hadronic atoms

    International Nuclear Information System (INIS)

    Poth, H.

    1979-01-01

    This compilation is a survey of the existing data of hadronic atoms (pionic-atoms, kaonic-atoms, antiprotonic-atoms, sigmonic-atoms). It collects measurements of the energies, intensities and line width of X-rays from hadronic atoms. Averaged values for each hadronic atom are given and the data are summarized. The listing contains data on 58 pionic-atoms, on 54 kaonic-atoms, on 23 antiprotonic-atoms and on 20 sigmonic-atoms. (orig./HB) [de

  17. Tightly confined atoms in optical dipole traps

    International Nuclear Information System (INIS)

    Schulz, M.

    2002-12-01

    This thesis reports on the design and setup of a new atom trap apparatus, which is developed to confine few rubidium atoms in ultrahigh vacuum and make them available for controlled manipulations. To maintain low background pressure, atoms of a vapour cell are transferred into a cold atomic beam by laser cooling techniques, and accumulated by a magneto-optic trap (MOT) in a separate part of the vacuum system. The laser cooled atoms are then transferred into dipole traps made of focused far-off-resonant laser fields in single- or crossed-beam geometry, which are superimposed with the center of the MOT. Gaussian as well as hollow Laguerre-Gaussian (LG$ ( 01)$) beam profiles are used with red-detuned or blue-detuned light, respectively. Microfabricated dielectric phase objects allow efficient and robust mode conversion of Gaussian into Laguerre-Gaussian laser beams. Trap geometries can easily be changed due to the highly flexible experimental setup. The dipole trap laser beams are focused to below 10 microns at a power of several hundred milliwatts. Typical trap parameters, at a detuning of several ten nanometers from the atomic resonance, are trag depths of few millikelvin, trap frequencies near 30-kHz, trap light scattering rates of few hundred photons per atom and second, and lifetimes of several seconds. The number of dipole-trapped atoms ranges from more than ten thousand to below ten. The dipole-trapped atoms are detected either by a photon counting system with very efficient straylight discrimination, or by recapture into the MOT, which is imaged onto a sensitive photodiode and a CCD-camera. Due to the strong AC-Stark shift imposed by the high intensity trapping light, energy-selective resonant excitation and detection of the atoms is possible. The measured energy distribution is consistent with a harmonic potential shape and allows the determination of temperatures and heating rates. In first measurements, the thermal energy is found to be about 10 % of the

  18. CP violation in atoms

    International Nuclear Information System (INIS)

    Barr, S.M.

    1992-01-01

    Electric dipole moments of large atoms are an excellent tool to search for CP violation beyond the Standard Model. These tell us about the electron EDM but also about CP-violating electron-nucleon dimension-6 operators that arise from Higgs-exchange. Rapid strides are being made in searches for atomic EDMs. Limits on the electron EDM approaching the values which would be expected from Higgs-exchange mediated CP violation have been achieved. It is pointed out that in this same kind of model if tan β is large the effects in atoms of the dimension-6 e - n operators may outweigh the effect of the electron EDM. (author) 21 refs

  19. US Atomic Energy Law

    International Nuclear Information System (INIS)

    1981-01-01

    This is a new volume follows in the series supplementing the volumes 11 and 12 published in 1965 and 1966, updating the collection of Federal Acts and Executive Orders of the President of the United States of America relating to atomic energy legislation. Since the publication of volumes 11 and 12, the US Atomic Energy Act of 1954 alone has been amended 25 times, mainly as a consequence of by the Nuclear Non-Proliferation Act and the Uranium Mill Tailings Radiation Control Act, both of 1978. The Atomic Energy Act of 1954 is supplemented by a selection of the most important Federal Acts, Executive Orders of the President and Resolutions of the Congress. (orig./HSCH) [de

  1. Atomic profits, no thanks

    International Nuclear Information System (INIS)

    Bartels, W.; Dietrich, K.; Moeller, H.; Speier, C.

    1980-01-01

    The authors deal with the following topics: The secret of nuclear energy; the atom programmes of Bonn; on some arguments of the present nuclear energy discussion; how socialist countries solve the problems of nuclear energy. From the socialist point of view they discuss sociological, ideological and moral reasons for a peaceful utilization of nuclear energy. Nevertheless they refuse Bonn's atom programme because the high finance's interests concerning profit and power make it a danger. The biggest danger is said to lie in the creation of a plutonium-industry and the militaristic abuse which would be connected with it. The socialist way of utilizing atomic energy is seen by them as a way with a high feeling of responsibility towards all people and towards a guaranteed energy supply. (HSCH) [de

  2. Controlling the atom

    International Nuclear Information System (INIS)

    Mazuzan, G.T.; Walker, J.S.

    1984-01-01

    The authors trace the early history of nuclear power regulation in the US. Focusing on the Atomic Energy Commission, they describe the role of other groups that figured in the development of regulatory policies, including the Congressional Joint Committee on Atomic Energy, other federal agencies, state governments, the nuclear industry, and scientific organizations. They consider changes in public perceptions of and attitudes toward atomic energy and the dangers of radiation exposure. The basic purpose of the book is to provide the Nuclear Regulatory Commission and the general public with information on the historical antecedents and background of regulatory issues so that there will be continuity in policy decisions. The book concludes with an annotated bibliography of selected references. 19 figures

  3. Rydberg atoms in strong fields

    International Nuclear Information System (INIS)

    Kleppner, D.; Tsimmerman, M.

    1985-01-01

    Experimental and theoretical achievements in studying Rydberg atoms in external fields are considered. Only static (or quasistatic) fields and ''one-electron'' atoms, i.e. atoms that are well described by one-electron states, are discussed. Mainly behaviour of alkali metal atoms in electric field is considered. The state of theoretical investigations for hydrogen atom in magnetic field is described, but experimental data for atoms of alkali metals are presented as an illustration. Results of the latest experimental and theoretical investigations into the structure of Rydberg atoms in strong fields are presented

  4. Atoms in Slovakia

    International Nuclear Information System (INIS)

    Danis, D.; Feik, K.; Florek, M.; Kmosena, J.; Chrapan, J.; Morovic, M.; Slugen, V.; Seliga, M.; Valovic, J.

    2006-01-01

    In this book the history of development of using of nuclear energy in the Slovak Republic as well as in the Czechoslovakia (before 1993 year) is presented. The aim of the book is to preserve the memory of the period when the creation and development of nuclear physics, technology, nuclear medicine, radioecology and energetics in Slovakia occurred - as witnessed by people who experienced this period and to adapt it to future generations. The Editorial board of the SNUS collected the views of 60 contributors and distinguished workers - Slovakian experts in nuclear science, education and technology. Calling upon a wide spectrum of experts ensured an objective historical description of the period. A huge amount of subjective views on recent decades were collected and supported by a wealth of photographic documentation. This created a synthesised reflection on the history of the 'atoms' in Slovakia. The book contains 15 tables, 192 black and white and 119 colour pictures from around the world and from places involved in the compilation of the study and with the study of atomic science in Slovakia. The main chapters are as follows: Atoms in the world, Atoms in Slovakia, Atoms in the educational system, Atoms in health services (Radiology, Nuclear medicine, Radiation protection, the Cyclotron centre of the Slovak Republic), Radioecology, Other applications of irradiation, Nuclear energetics (Electric energy in the second half of the 20 th century, NPP Bohunice, NPP Mochovce, the back-end of Nuclear energetics, Big names in Nuclear energetics in Slovakia), Chronology and an Appendix entitled 'Slovak companies in nuclear energetics'

  5. Positron-atom collisions

    International Nuclear Information System (INIS)

    Drachman, R.J.

    1984-01-01

    The past decade has seen the field of positron-atom collisions mature into an important sub-field of atomic physics. Increasingly intense positron sources are leading towards a situation in which electron and positron collision experiments will be on almost an equal footing, challenging theory to analyze their similarities and differences. The author reviews the advances made in theory, including dispersion theory, resonances, and inelastic processes. A survey of experimental progress and a brief discussion of astrophysical positronics is also included. (Auth.)

  6. 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.

  7. 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

  8. Atomic cluster collisions

    Science.gov (United States)

    Korol, Andrey V.; Solov'yov, Andrey

    2013-01-01

    Atomic cluster collisions are a field of rapidly emerging research interest by both experimentalists and theorists. The international symposium on atomic cluster collisions (ISSAC) is the premier forum to present cutting-edge research in this field. It was established in 2003 and the most recent conference was held in Berlin, Germany in July of 2011. This Topical Issue presents original research results from some of the participants, who attended this conference. This issues specifically focuses on two research areas, namely Clusters and Fullerenes in External Fields and Nanoscale Insights in Radiation Biodamage.

  9. Pulsed atomic soliton laser

    International Nuclear Information System (INIS)

    Carr, L.D.; Brand, J.

    2004-01-01

    It is shown that simultaneously changing the scattering length of an elongated, harmonically trapped Bose-Einstein condensate from positive to negative and inverting the axial portion of the trap, so that it becomes expulsive, results in a train of self-coherent solitonic pulses. Each pulse is itself a nondispersive attractive Bose-Einstein condensate that rapidly self-cools. The axial trap functions as a waveguide. The solitons can be made robustly stable with the right choice of trap geometry, number of atoms, and interaction strength. Theoretical and numerical evidence suggests that such a pulsed atomic soliton laser can be made in present experiments

  10. Frequency noise in frequency swept fiber laser

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2013-01-01

    This Letter presents a measurement of the spectral content of frequency shifted pulses generated by a lightwave synthesized frequency sweeper. We found that each pulse is shifted in frequency with very high accuracy. We also discovered that noise originating from light leaking through the acousto......- optical modulators and forward propagating Brillouin scattering appear in the spectrum. © 2013 Optical Society of America....

  11. 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

  12. Polarized atomic beams for targets

    International Nuclear Information System (INIS)

    Grueebler, W.

    1984-01-01

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

  13. Chemisorption-Induced Resonance Frequency Shift of a Microcantilever

    International Nuclear Information System (INIS)

    Zhang Ji-Qiao; Feng Xi-Qiao; Yu Shou-Wen; Huang Gan-Yun

    2012-01-01

    The autonomy and property of atoms/molecules adsorbed on the surface of a microcantilever can be probed by measuring its resonance frequency shift due to adsorption. The resonance frequency change of a cantilever induced by chemisorption is theoretically studied. Oxygen chemisorbed on the Si(100) surface is taken as a representative example. We demonstrate that the resonant response of the cantilever is mainly determined by the chemisorption-induced bending stiffness variation, which depends on the bond configurations formed by the adsorbed atoms and substrate atoms. This study is helpful for optimal design of microcantilever-based sensors for various applications. (condensed matter: structure, mechanical and thermal properties)

  14. Atomic collisions related to atomic laser isotope separation

    International Nuclear Information System (INIS)

    Shibata, Takemasa

    1995-01-01

    Atomic collisions are important in various places in atomic vapor laser isotope separation (AVLIS). At a vaporization zone, many atomic collisions due to high density have influence on the atomic beam characteristics such as velocity distribution and metastable states' populations at a separation zone. In the separation zone, a symmetric charge transfer between the produced ions and the neutral atoms may degrade selectivity. We have measured atomic excitation temperatures of atomic beams and symmetric charge transfer cross sections for gadolinium and neodymium. Gadolinium and neodymium are both lanthanides. Nevertheless, results for gadolinium and neodymium are very different. The gadolinium atom has one 5d electron and neodymium atom has no 5d electron. It is considered that the differences are due to existence of 5d electron. (author)

  15. Spatially resolved photoionization of ultracold atoms on an atom chip

    International Nuclear Information System (INIS)

    Kraft, S.; Guenther, A.; Fortagh, J.; Zimmermann, C.

    2007-01-01

    We report on photoionization of ultracold magnetically trapped Rb atoms on an atom chip. The atoms are trapped at 5 μK in a strongly anisotropic trap. Through a hole in the chip with a diameter of 150 μm, two laser beams are focused onto a fraction of the atomic cloud. A first laser beam with a wavelength of 778 nm excites the atoms via a two-photon transition to the 5D level. With a fiber laser at 1080 nm the excited atoms are photoionized. Ionization leads to depletion of the atomic density distribution observed by absorption imaging. The resonant ionization spectrum is reported. The setup used in this experiment is suitable not only to investigate mixtures of Bose-Einstein condensates and ions but also for single-atom detection on an atom chip

  16. Atomic Interferometry with Detuned Counter-Propagating Electromagnetic Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Tsang, Ming -Yee [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-09-05

    Atomic fountain interferometry uses atoms cooled with optical molasses to 1 μK, which are then launched in a fountain mode. The interferometer relies on the nonlinear Raman interaction of counter-propagating visible light pulses. We present models of these key transitions through a series of Hamiltonians. Our models, which have been verified against special cases with known solutions, allow us to incorporate the effects of non-ideal pulse shapes and realistic laser frequency or wavevector jitter.

  17. Long distance measurement with a femtosecond laser based frequency comb

    Science.gov (United States)

    Bhattacharya, N.; Cui, M.; Zeitouny, M. G.; Urbach, H. P.; van den Berg, S. A.

    2017-11-01

    Recent advances in the field of ultra-short pulse lasers have led to the development of reliable sources of carrier envelope phase stabilized femtosecond pulses. The pulse train generated by such a source has a frequency spectrum that consists of discrete, regularly spaced lines known as a frequency comb. In this case both the frequency repetition and the carrier-envelope-offset frequency are referenced to a frequency standard, like an atomic clock. As a result the accuracy of the frequency standard is transferred to the optical domain, with the frequency comb as transfer oscillator. These unique properties allow the frequency comb to be applied as a versatile tool, not only for time and frequency metrology, but also in fundamental physics, high-precision spectroscopy, and laser noise characterization. The pulse-to-pulse phase relationship of the light emitted by the frequency comb has opened up new directions for long range highly accurate distance measurement.

  18. Two-dimensional atom localization based on coherent field controlling in a five-level M-type atomic system.

    Science.gov (United States)

    Jiang, Xiangqian; Li, Jinjiang; Sun, Xiudong

    2017-12-11

    We study two-dimensional sub-wavelength atom localization based on the microwave coupling field controlling and spontaneously generated coherence (SGC) effect. For a five-level M-type atom, introducing a microwave coupling field between two upper levels and considering the quantum interference between two transitions from two upper levels to lower levels, the analytical expression of conditional position probability (CPP) distribution is obtained using the iterative method. The influence of the detuning of a spontaneously emitted photon, Rabi frequency of the microwave field, and the SGC effect on the CPP are discussed. The two-dimensional sub-half-wavelength atom localization with high-precision and high spatial resolution is achieved by adjusting the detuning and the Rabi frequency, where the atom can be localized in a region smaller thanλ/10×λ/10. The spatial resolution is improved significantly compared with the case without the microwave field.

  19. Highly versatile atomic micro traps generated by multifrequency magnetic field modulation

    International Nuclear Information System (INIS)

    Courteille, Ph W; Deh, B; Fortagh, J; Guenther, A; Kraft, S; Marzok, C; Slama, S; Zimmermann, C

    2006-01-01

    We propose the realization of custom-designed adiabatic potentials for cold atoms based on multimode radio frequency radiation in combination with static inhomogeneous magnetic fields. For example, the use of radio frequency combs gives rise to periodic potentials acting as gratings for cold atoms. In strong magnetic field gradients, the lattice constant can be well below 1 μm. By changing the frequencies of the comb in time the gratings can easily be propagated in space, which may prove useful for Bragg scattering atomic matter waves. Furthermore, almost arbitrarily shaped potentials are possible such as disordered potentials on a scale of several 100 nm or lattices with a spatially varying lattice constant. The potentials can be made state selective and, in the case of atomic mixtures, also species selective. This opens new perspectives for generating tailored quantum systems based on ultracold single atoms or degenerate atomic and molecular quantum gases

  20. Sugarcane crop efficiency in two growing seasons in São Paulo State, Brazil Eficiência da produção de cana-de-açúcar em duas safras no Estado de São Paulo

    Directory of Open Access Journals (Sweden)

    Fábio Ricardo Marin

    2008-11-01

    Full Text Available A conceptual framework for crop production efficiency was derived using thermodynamic efficiency concept, in order to generate a tool for performance evaluation of agricultural systems and to quantify the interference of determining factors on this performance. In Thermodynamics, efficiency is the ratio between the output and input of energy. To establish this relationship in agricultural systems, it was assumed that the input energy is represented by the attainable crop yield, as predicted through simulation models based on environmental variables. The method of FAO's agroecological zones was applied to the assessment of the attainable sugarcane yield, while Instituto Brasileiro de Geografia e Estatística (IBGE data were used as observed yield. Sugarcane efficiency production in São Paulo state was evaluated in two growing seasons, and its correlation with some physical factors that regulate production was calculated. A strong relationship was identified between crop production efficiency and soil aptitude. This allowed inferring the effect of agribusiness factors on crop production efficiency. The relationships between production efficiency and climatic variables were also quantified and indicated that solar radiation, annual rainfall, water deficiency, and maximum air temperature are the main factors affecting the sugarcane production efficiency.Um conceito de eficiência de produção agrícola foi derivado da Termodinâmica, para gerar um indicador para avaliação do desempenho de sistemas de produção agrícola e quantificação da interferência dos fatores determinantes desse desempenho. Em Termodinâmica, a eficiência de um processo é dada pela razão entre a energia recuperada e a energia utilizada. Para estabelecer essa relação em sistemas agrícolas, admitiu-se que a energia utilizada seja dada pela produtividade atingível, estimada por modelos de simulação desenvolvidos com base em variáveis ambientais. O método das

  1. Atomic physics through astrophysics

    International Nuclear Information System (INIS)

    Dalgarno, A.

    1987-01-01

    Astronomical environments encompass an extreme range of physical conditions of temperature, density, pressure and radiation fields and unusual situations abound. In this lecture, the author describes some of the objects found in the Universe and discussed the atomic processes that occur. 45 references, 8 figures

  2. Rutherford-Bohr atom

    Science.gov (United States)

    Heilbron, J. L.

    1981-03-01

    Bohr used to introduce his attempts to explain clearly the principles of the quantum theory of the atom with an historical sketch, beginning invariably with the nuclear model proposed by Rutherford. That was sound pedagogy but bad history. The Rutherford-Bohr atom stands in the middle of a line of work initiated by J.J. Thomson and concluded by the invention of quantum mechanics. Thompson's program derived its inspiration from the peculiar emphasis on models characteristic of British physics of the 19th century. Rutherford's atom was a late product of the goals and conceptions of Victorian science. Bohr's modifications, although ultimately fatal to Thomson's program, initially gave further impetus to it. In the early 1920s the most promising approach to an adequate theory of the atom appeared to be the literal and detailed elaboration of the classical mechanics of multiply periodic orbits. The approach succeeded, demonstrating in an unexpected way the force of an argument often advanced by Thomson: because a mechanical model is richer in implications than the considerations for which it was advanced, it can suggest new directions of research that may lead to important discoveries.

  3. Deep diode atomic battery

    International Nuclear Information System (INIS)

    Anthony, T.R.; Cline, H.E.

    1977-01-01

    A deep diode atomic battery is made from a bulk semiconductor crystal containing three-dimensional arrays of columnar and lamellar P-N junctions. The battery is powered by gamma rays and x-ray emission from a radioactive source embedded in the interior of the semiconductor crystal

  4. Atoms in Astronomy.

    Science.gov (United States)

    Blanchard, Paul A.

    This booklet is part of an American Astronomical Society curriculum project designed to provide teaching materials to teachers of secondary school chemistry, physics, and earth science. A Basic Topics section discusses atomic structure, emphasizing states of matter at high temperature and spectroscopic analysis of light from the stars. A section…

  5. Atomic energy and you

    International Nuclear Information System (INIS)

    1975-01-01

    The film discusses the peaceful applications of atomic energy in agriculture, engineering, industry and medicine. Shows exploration, prospecting and mining of uraninum ores at Larap, Camarines Norte and the study of geographical conditions of the site for the proposed Nuclear Power Plant in Bataan

  6. Discovery and the atom

    International Nuclear Information System (INIS)

    1989-01-01

    ''Discovery and the Atom'' tells the story of the founding of nuclear physics. This programme looks at nuclear physics up to the discovery of the neutron in 1932. Animation explains the science of the classic experiments, such as the scattering of alpha particles by Rutherford and the discovery of the nucleus. Archive film shows the people: Lord Rutherford, James Chadwick, Marie Curie. (author)

  7. Atomically resolved tissue integration.

    Science.gov (United States)

    Karlsson, Johan; Sundell, Gustav; Thuvander, Mattias; Andersson, Martin

    2014-08-13

    In the field of biomedical technology, a critical aspect is the ability to control and understand the integration of an implantable device in living tissue. Despite the technical advances in the development of biomaterials, the elaborate interplay encompassing materials science and biology on the atomic level is not very well understood. Within implantology, anchoring a biomaterial device into bone tissue is termed osseointegration. In the most accepted theory, osseointegration is defined as an interfacial bonding between implant and bone; however, there is lack of experimental evidence to confirm this. Here we show that atom probe tomography can be used to study the implant-tissue interaction, allowing for three-dimensional atomic mapping of the interface region. Interestingly, our analyses demonstrated that direct contact between Ca atoms and the implanted titanium oxide surface is formed without the presence of a protein interlayer, which means that a pure inorganic interface is created, hence giving experimental support to the current theory of osseointegration. We foresee that this result will be of importance in the development of future biomaterials as well as in the design of in vitro evaluation techniques.

  8. Atomic transport properties

    International Nuclear Information System (INIS)

    Freyss, M.

    2015-01-01

    As presented in the first chapter of this book, atomic transport properties govern a large panel of nuclear fuel properties, from its microstructure after fabrication to its behaviour under irradiation: grain growth, oxidation, fission product release, gas bubble nucleation. The modelling of the atomic transport properties is therefore the key to understanding and predicting the material behaviour under irradiation or in storage conditions. In particular, it is noteworthy that many modelling techniques within the so-called multi-scale modelling scheme of materials make use of atomic transport data as input parameters: activation energies of diffusion, diffusion coefficients, diffusion mechanisms, all of which are then required to be known accurately. Modelling approaches that are readily used or which could be used to determine atomic transport properties of nuclear materials are reviewed here. They comprise, on the one hand, static atomistic calculations, in which the migration mechanism is fixed and the corresponding migration energy barrier is calculated, and, on the other hand, molecular dynamics calculations and kinetic Monte-Carlo simulations, for which the time evolution of the system is explicitly calculated. (author)

  9. Experimental atomic physics

    International Nuclear Information System (INIS)

    Sellin, I.A.; Elston, S.B.; Forester, J.P.; Liao, K.H.; Pegg, D.J.; Peterson, R.S.; Thoe, R.S.; Hayden, H.C.; Griffin, P.M.

    1976-01-01

    The atomic structure and collision phenomena of highly stripped ions in the range Z = 6 to 35 were studied. Charge-transfer and multiple-electron-loss cross sections were determined. Absolute x-ray-production cross sections for incident heavy ions were measured. 10 figures, 1 table

  10. Transition probabilities for atoms

    International Nuclear Information System (INIS)

    Kim, Y.K.

    1980-01-01

    Current status of advanced theoretical methods for transition probabilities for atoms and ions is discussed. An experiment on the f values of the resonance transitions of the Kr and Xe isoelectronic sequences is suggested as a test for the theoretical methods

  11. 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.)

  12. 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)

  13. Coherent atomic spectroscopy

    International Nuclear Information System (INIS)

    Garton, W.R.S.

    1988-01-01

    The Argonne Spectroscopy Laboratory, initiated and advanced over several decades by F.S. Tomkins and M. Fred, has been a major international facility. A range of collaborative work in atomic spectroscopy is selected to illustrate advances in experimental physics which have been made possible by combination of the talents of Tomkins and Fred with the unique facilities of the Argonne Laboratory. (orig.)

  14. Spectra of alkali atoms

    International Nuclear Information System (INIS)

    Santoso, Budi; Arumbinang, Haryono.

    1981-01-01

    Emission spectra of alkali atoms has been determined by using spectrometer at the ultraviolet to infra red waves range. The spectra emission can be obtained by absorption spectrophotometric analysis. Comparative evaluations between experimental data and data handbook obtained by spark method were also presented. (author tr.)

  15. 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.

  16. Atomic Physics 16: Sixteenth International Conference on Atomic Physics. Proceedings

    International Nuclear Information System (INIS)

    Baylis, W.E.; Drake, G.W.

    1999-01-01

    These proceedings represent papers presented at the 16th International Conference on Atomic Physics held in Windsor, Ontario, Canada, in August, 1998. The topics discussed included a wide array of subjects in atomic physics such as atom holography, alignment in atomic collisions, coulomb-interacting particles, muon experiments, x-rays from comets, atomic electron collisions in intense laser fields, spectroscopy of trapped ions, and Bose-Einstein condensates. This conference represents the single most important meeting world wide on fundamental advances in atomic physics. There were 30 papers presented at the conference,out of which 4 have been abstracted for the Energy, Science and Technology database

  17. Collapse–revival of squeezing of two atoms in dissipative cavities

    International Nuclear Information System (INIS)

    Zou Hong-Mei; Fang Mao-Fa

    2016-01-01

    Based on the time-convolutionless master-equation approach, we investigate the squeezing dynamics of two atoms in dissipative cavities. We find that the atomic squeezing is related to initial atomic states, atom–cavity couplings, non-Markovian effects and resonant frequencies of an atom and its cavity. The results show that a collapse–revival phenomenon will occur in the atomic squeezing and this process is accompanied by the buildup and decay of entanglement between two atoms. Enhancing the atom–cavity coupling can increase the frequency of the collapse–revival of the atomic squeezing. The stronger the non-Markovian effect is, the more obvious the collapse–revival phenomenon is. In particular, if the atom–cavity coupling or the non-Markovian effect is very strong, the atomic squeezing will tend to a stably periodic oscillation in a long time. The oscillatory frequency of the atomic squeezing is dependent on the resonant frequency of the atom and its cavity. (paper)

  18. Point source atom interferometry with a cloud of finite size

    Energy Technology Data Exchange (ETDEWEB)

    Hoth, Gregory W., E-mail: gregory.hoth@nist.gov; Pelle, Bruno; Riedl, Stefan; Kitching, John; Donley, Elizabeth A. [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)

    2016-08-15

    We demonstrate a two axis gyroscope by the use of light pulse atom interferometry with an expanding cloud of atoms in the regime where the cloud has expanded by 1.1–5 times its initial size during the interrogation. Rotations are measured by analyzing spatial fringe patterns in the atom population obtained by imaging the final cloud. The fringes arise from a correlation between an atom's initial velocity and its final position. This correlation is naturally created by the expansion of the cloud, but it also depends on the initial atomic distribution. We show that the frequency and contrast of these spatial fringes depend on the details of the initial distribution and develop an analytical model to explain this dependence. We also discuss several challenges that must be overcome to realize a high-performance gyroscope with this technique.

  19. Prospects for Precise Measurements with Echo Atom Interferometry

    Directory of Open Access Journals (Sweden)

    Brynle Barrett

    2016-06-01

    Full Text Available Echo atom interferometers have emerged as interesting alternatives to Raman interferometers for the realization of precise measurements of the gravitational acceleration g and the determination of the atomic fine structure through measurements of the atomic recoil frequency ω q . Here we review the development of different configurations of echo interferometers that are best suited to achieve these goals. We describe experiments that utilize near-resonant excitation of laser-cooled rubidium atoms by a sequence of standing wave pulses to measure ω q with a statistical uncertainty of 37 parts per billion (ppb on a time scale of ∼50 ms and g with a statistical precision of 75 ppb. Related coherent transient techniques that have achieved the most statistically precise measurements of atomic g-factor ratios are also outlined. We discuss the reduction of prominent systematic effects in these experiments using off-resonant excitation by low-cost, high-power lasers.

  20. Dynamic polarizability of a complex atom in strong laser fields

    International Nuclear Information System (INIS)

    Rapoport, L.P.; Klinskikh, A.F.; Mordvinov, V.V.

    1997-01-01

    An asymptotic expansion of the dynamic polarizability of a complex atom in a strong circularly polarized light field is found for the case of high frequencies. The self-consistent approximation of the Hartree-Fock type for the ''atom+field'' system is developed, within the framework of which a numerical calculation of the dynamic polarizability of Ne, Kr, and Ar atoms in a strong radiation field is performed. The strong field effect is shown to manifest itself not only in a change of the energy spectrum and the character of behavior of the wave functions of atomic electrons, but also in a modification of the one-electron self-consistent potential for the atom in the field