Simulation of coherent interactions between Rydberg atoms

International Nuclear Information System (INIS)

Robicheaux, F.; Hernandez, J.V.; Topcu, T.; Noordam, L.D.

2004-01-01

The results of a theoretical investigation of the coherent interaction between many Rydberg atoms are reported. The atoms are assumed to move very little during the time range we investigate. We describe the basic interaction between atoms and show that (contrary to previous theoretical studies) the interaction between the atoms can be coherent. The band structure for a perfect lattice of atoms and the density of states for an amorphous distribution of atoms are presented. We also give results for when the atoms are roughly positioned in a lattice. Finally, we performed detailed calculations to understand when the Rydberg interactions are too strong for an essential states type of approximation. The relevance of our results to previous measurements in a Rydberg gas and to possible future experiments is discussed

Janne Rydberg - his life and work

International Nuclear Information System (INIS)

Martinson, I.; Curtis, L.J.

2005-01-01

The Rydberg formula is emblematic of atomic spectroscopy. We review here the personal background, research accomplishments, and academic career of its discoverer, Janne Rydberg. Although his formula is often introduced as a generalization of the hydrogenic Balmer formula, Rydberg's work was independent of Balmer's, and displayed great ingenuity and a rare ability to recognize hidden patterns in complex numerical data. Although his discoveries attracted wide attention, experimental physics was then considered inseparable from measurement, and the fact that Rydberg's insightful formulations used the data of others impeded his academic career. Although Rydberg did not live to see the full theoretical implications of his discoveries, the vigorous study of Rydberg atoms continues today

Stimulated adiabatic passage in a dissipative ensemble of atoms with strong Rydberg-state interactions

DEFF Research Database (Denmark)

Petrosyan, David; Molmer, Klaus

2013-01-01

We study two-photon excitation of Rydberg states of atoms under stimulated adiabatic passage with delayed laser pulses. We find that the combination of strong interaction between the atoms in Rydberg state and the spontaneous decay of the intermediate exited atomic state leads to the Rydberg exci...... for deterministic creation and, possibly, extraction of Rydberg atoms or ions one at a time. The sympathetic monitoring via decay of ancilla particles may find wider applications for state preparation and probing of interactions in dissipative many-body systems.......We study two-photon excitation of Rydberg states of atoms under stimulated adiabatic passage with delayed laser pulses. We find that the combination of strong interaction between the atoms in Rydberg state and the spontaneous decay of the intermediate exited atomic state leads to the Rydberg...

Correlations between interacting Rydberg atoms

Science.gov (United States)

Paris-Mandoki, Asaf; Braun, Christoph; Hofferberth, Sebastian

2018-04-01

This paper is a short introduction to Rydberg physics and quantum nonlinear optics using Rydberg atoms. It has been prepared as a compliment to a series of lectures delivered during the Latin American School of Physics "Marcos Moshinsky" 2017. We provide a short introduction to the properties of individual Rydberg atoms and discuss in detail how the interaction potential between Rydberg atom pairs is calculated. We then discuss how this interaction gives rise to the Rydberg blockade mechanism. With the aid of hallmark experiments in the field applications of the blockade for creating correlated quantum systems are discussed. Our aim is to give an overview of this exciting and rapidly evolving field. The interested reader is referred to original work and more comprehensive reviews and tutorials for further details on these subjects.

Bohmian picture of Rydberg atoms

Indian Academy of Sciences (India)

Abstract. Unlike the previous theoretical results based on standard quantum mechanics that established the nearly elliptical shapes for the centre-of-mass motion in Rydberg atoms using numerical simulations, we show analytically that the Bohmian trajectories in Rydberg atoms are nearly elliptical.

Calculation of Rydberg interaction potentials

International Nuclear Information System (INIS)

Weber, Sebastian; Büchler, Hans Peter; Tresp, Christoph; Urvoy, Alban; Hofferberth, Sebastian; Menke, Henri; Firstenberg, Ofer

2017-01-01

The strong interaction between individual Rydberg atoms provides a powerful tool exploited in an ever-growing range of applications in quantum information science, quantum simulation and ultracold chemistry. One hallmark of the Rydberg interaction is that both its strength and angular dependence can be fine-tuned with great flexibility by choosing appropriate Rydberg states and applying external electric and magnetic fields. More and more experiments are probing this interaction at short atomic distances or with such high precision that perturbative calculations as well as restrictions to the leading dipole–dipole interaction term are no longer sufficient. In this tutorial, we review all relevant aspects of the full calculation of Rydberg interaction potentials. We discuss the derivation of the interaction Hamiltonian from the electrostatic multipole expansion, numerical and analytical methods for calculating the required electric multipole moments and the inclusion of electromagnetic fields with arbitrary direction. We focus specifically on symmetry arguments and selection rules, which greatly reduce the size of the Hamiltonian matrix, enabling the direct diagonalization of the Hamiltonian up to higher multipole orders on a desktop computer. Finally, we present example calculations showing the relevance of the full interaction calculation to current experiments. Our software for calculating Rydberg potentials including all features discussed in this tutorial is available as open source. (tutorial)

Robustness of high-fidelity Rydberg gates with single-site addressability

Science.gov (United States)

Goerz, Michael H.; Halperin, Eli J.; Aytac, Jon M.; Koch, Christiane P.; Whaley, K. Birgitta

2014-09-01

Controlled-phase (cphase) gates can be realized with trapped neutral atoms by making use of the Rydberg blockade. Achieving the ultrahigh fidelities required for quantum computation with such Rydberg gates, however, is compromised by experimental inaccuracies in pulse amplitudes and timings, as well as by stray fields that cause fluctuations of the Rydberg levels. We report here a comparative study of analytic and numerical pulse sequences for the Rydberg cphase gate that specifically examines the robustness of the gate fidelity with respect to such experimental perturbations. Analytical pulse sequences of both simultaneous and stimulated Raman adiabatic passage (STIRAP) are found to be at best moderately robust under these perturbations. In contrast, optimal control theory is seen to allow generation of numerical pulses that are inherently robust within a predefined tolerance window. The resulting numerical pulse shapes display simple modulation patterns and can be rationalized in terms of an interference between distinct two-photon Rydberg excitation pathways. Pulses of such low complexity should be experimentally feasible, allowing gate fidelities of order 99.90-99.99% to be achievable under realistic experimental conditions.

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

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

saturated absorption spectrum of the D2 line, the stabilization point of the UV laser can be detuned from the resonance by discrete values. Using this idea, we demonstrate the stability of the frequency locking scheme with an atomic beam apparatus: if the detuned laser hits the atomic beam under a small angle, only atoms of a certain velocity class will be transferred to their upper level. We excite the atoms with pulses of 5 μsec duration and measure their arrival times 10 cm behind the excitation region with field selective ionization. By analyzing the time of flight spreading we can show that the long-term linewidth of the laser is below 2 MHz in the UV, which corresponds to the specified short time stability of the dye laser and the long term frequency drift can be effectively compensated. (author)

Magnetic trapping of Rydberg atoms

NARCIS (Netherlands)

Niestadt, D.; Naber, J.; Kokkelmans, S.J.J.M.F.; Spreeuw, R.J.C.

2016-01-01

Magnetic trapping is a well-established technique for ground state atoms. We seek to extend this concept to Rydberg atoms. Rydberg atoms are important for current visions of quantum simulators that will be used in the near future to simulate and analyse quantum problems. Current efforts in Amsterdam

Laser desorption/ionization time-of-flight mass spectrometry of triacylglycerols and other components in fingermark samples.

Science.gov (United States)

Emerson, Beth; Gidden, Jennifer; Lay, Jackson O; Durham, Bill

2011-03-01

The chemical composition of fingermarks could potentially be important for determining investigative leads, placing individuals at the time of a crime, and has applications as biomarkers of disease. Fingermark samples containing triacylglycerols (TAGs) and other components were analyzed using laser desorption/ionization (LDI) time-of-flight mass spectrometry (TOF MS). Only LDI appeared to be useful for this application while conventional matrix-assisted LDI-TOF MS was not. Tandem MS was used to identify/confirm selected TAGs. A limited gender comparison, based on a simple t-distribution and peaks intensities, indicated that two TAGs showed gender specificity at the 95% confidence level and two others at 97.5% confidence. Because gender-related TAGs differences were most often close to the standard deviation of the measurements, the majority of the TAGs showed no gender specificity. Thus, LDI-TOF MS is not a reliable indicator of gender based on fingermark analysis. Cosmetic ingredients present in some samples were identified. © 2011 American Academy of Forensic Sciences.

Evidence of Antiblockade in an Ultracold Rydberg Gas

Science.gov (United States)

Amthor, Thomas; Giese, Christian; Hofmann, Christoph S.; Weidemüller, Matthias

2010-01-01

We present the experimental observation of the antiblockade in an ultracold Rydberg gas recently proposed by Ates et al. [Phys. Rev. Lett. 98, 023002 (2007)PRLTAO0031-900710.1103/PhysRevLett.98.023002]. Our approach allows the control of the pair distribution in the gas and is based on a strong coupling of one transition in an atomic three-level system, while introducing specific detunings of the other transition. When the coupling energy matches the interaction energy of the Rydberg long-range interactions, the otherwise blocked excitation of close pairs becomes possible. A time-resolved spectroscopic measurement of the Penning ionization signal is used to identify slight variations in the Rydberg pair distribution of a random arrangement of atoms. A model based on a pair interaction Hamiltonian is presented which well reproduces our experimental observations and allows one to deduce the distribution of nearest-neighbor distances.

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

Wave-packet approach to Rydberg resonances in dissociative recombination

International Nuclear Information System (INIS)

Morisset, Sabine; Pichl, Lukas; Orel, Ann E.; Schneider, Ioan F.

2007-01-01

We report the time-dependent approach to resonant electron capture into Rydberg states in collisions with molecular cations at low impact energy, as an alternative to the method based on multichannel quantum defect theory (MQDT), and present the results for the HD + ion. The propagation of the initial wave function on 13 Rydberg states (besides one valence state) correctly describes the indirect dissociative recombination mechanism in the time domain. Notably, the nonlocal coupling operator between the ionization and dissociation channels is accounted for in the indirect process, extending previous work on the case of direct coupling. The present approach compares to the MQDT framework with remarkable precision: resonant structures in the cross section correctly emerge from the wave-packet propagation; the time-dependent result also forms a cross section envelope for the dense series of ultrafine MQDT resonances corresponding to the quasicontinuous part of the Rydberg state manifold

Many-body quantum simulation with Rydberg atoms and ions

International Nuclear Information System (INIS)

Mueller, M.

2010-01-01

This thesis presents my work that is located at the interface between the fields of atomic physics, quantum optics and quantum information. The work was performed at the Institute of Theoretical Physics of the University of Innsbruck and the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences under the supervision of Prof. Peter Zoller. The main topic of this thesis is the investigation of new schemes for quantum simulation of interacting many-body systems. The thesis is divided into three parts, which cover my work on i) chains of trapped Rydberg ions ii) quantum information processing and simulation with Rydberg atoms and iii) quantum simulation with ground state ions. The first part of this thesis is concerned with the study of Rydberg ions trapped in a linear Paul trap. The properties of ionic Rydberg states in the presence of the static and time-dependent electric trapping fields are investigated. First it is analyzed under which conditions laser-excited Rydberg ions can be trapped in a stable configuration. Furthermore, it is shown that strong dipole-dipole interactions among the ions can be achieved by microwave dressing fields. These interactions can give rise to dynamics of Rydberg excitations through the ion crystal, which take place on a nanosecond timescale and can be described by effective spin-models. In addition, it is discussed how to achieve fast two-qubit entangling gates between pairs of Rydberg ions. In the second part of this thesis, novel possibilities of using neutral Rydberg atoms for quantum-information processing and quantum simulation are investigated. A new scheme for a multi-atom quantum gate is proposed and theoretically analyzed. This parallelized gate allows one to entangle a mesoscopic ensemble of atoms with a single control atom in a single step, with high fidelity and on a microsecond time scale. The operation relies on strong and long-ranged interactions between Rydberg atoms triggering a

Improving Rydberg Excitations within Time-Dependent Density Functional Theory with Generalized Gradient Approximations: The Exchange-Enhancement-for-Large-Gradient Scheme.

Science.gov (United States)

Li, Shaohong L; Truhlar, Donald G

2015-07-14

Time-dependent density functional theory (TDDFT) with conventional local and hybrid functionals such as the local and hybrid generalized gradient approximations (GGA) seriously underestimates the excitation energies of Rydberg states, which limits its usefulness for applications such as spectroscopy and photochemistry. We present here a scheme that modifies the exchange-enhancement factor to improve GGA functionals for Rydberg excitations within the TDDFT framework while retaining their accuracy for valence excitations and for the thermochemical energetics calculated by ground-state density functional theory. The scheme is applied to a popular hybrid GGA functional and tested on data sets of valence and Rydberg excitations and atomization energies, and the results are encouraging. The scheme is simple and flexible. It can be used to correct existing functionals, and it can also be used as a strategy for the development of new functionals.

Electromagnetically induced transparency of ultra-long-range Rydberg molecules

DEFF Research Database (Denmark)

Mirgorodskiy, Ivan; Christaller, Florian; Braun, Christoph

2017-01-01

We study the impact of Rydberg molecule formation on the storage and retrieval of Rydberg polaritons in an ultracold atomic medium. We observe coherent revivals appearing in the storage and retrieval efficiency of stored photons that originate from simultaneous excitation of Rydberg atoms and Ryd...

Electromagnetically Induced Transparency In Rydberg Atomic Medium

Science.gov (United States)

Deng, Li; Cong, Lu; Chen, Ai-Xi

2018-03-01

Due to possessing big principal quantum number, Rydberg atom has some unique properties, for example: its radiative lifetime is long, dipole moment is large, and interaction between atoms is strong and so on. These properties make one pay attention to Rydberg atoms. In this paper we investigate the effects of Rydberg dipole-dipole interactions on electromagnetically induced transparency (EIT) schemes and group velocity in three-level systems of ladder type, which provides theoretical foundation for exploring the linear and nonlinear characteristics of light in a Rydberg electromagnetically-induced-transparency medium.

revivals of Rydberg wave packets

International Nuclear Information System (INIS)

Bluhm, R.; Kostelecky, V.A.; Tudose, B.

1998-01-01

We examine the revival structure of Rydberg wave packets. The effects of quantum defects on wave packets in alkali-metal atoms and a squeezed-state description of the initial wave packets are also described. We then examine the revival structure of Rydberg wave packets in the presence of an external electric field, i.e., the revival structure of Stark wave packets. These wave packets have energies that depend on two quantum numbers and exhibit new types of interference behaviour

On the optimal identification of tag sets in time-constrained RFID configurations.

Science.gov (United States)

Vales-Alonso, Javier; Bueno-Delgado, María Victoria; Egea-López, Esteban; Alcaraz, Juan José; Pérez-Mañogil, Juan Manuel

2011-01-01

In Radio Frequency Identification facilities the identification delay of a set of tags is mainly caused by the random access nature of the reading protocol, yielding a random identification time of the set of tags. In this paper, the cumulative distribution function of the identification time is evaluated using a discrete time Markov chain for single-set time-constrained passive RFID systems, namely those ones where a single group of tags is assumed to be in the reading area and only for a bounded time (sojourn time) before leaving. In these scenarios some tags in a set may leave the reader coverage area unidentified. The probability of this event is obtained from the cumulative distribution function of the identification time as a function of the sojourn time. This result provides a suitable criterion to minimize the probability of losing tags. Besides, an identification strategy based on splitting the set of tags in smaller subsets is also considered. Results demonstrate that there are optimal splitting configurations that reduce the overall identification time while keeping the same probability of losing tags.

Calculation of Rydberg interaction potentials

DEFF Research Database (Denmark)

Weber, Sebastian; Tresp, Christoph; Menke, Henri

2017-01-01

The strong interaction between individual Rydberg atoms provides a powerful tool exploited in an ever-growing range of applications in quantum information science, quantum simulation and ultracold chemistry. One hallmark of the Rydberg interaction is that both its strength and angular dependence...... for calculating the required electric multipole moments and the inclusion of electromagnetic fields with arbitrary direction. We focus specifically on symmetry arguments and selection rules, which greatly reduce the size of the Hamiltonian matrix, enabling the direct diagonalization of the Hamiltonian up...

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

Analytical investigation of one-dimensional Rydberg atoms interacting with half-cycle pulses

International Nuclear Information System (INIS)

Bersons, I.; Veilande, R.

2004-01-01

Classical, quantum-mechanical, and semiclassical expressions for the transition probability in one-dimensional Rydberg atom irradiated by short half-cycle pulse are derived and compared. The simple formulas obtained for excitation of Rydberg atom by two time delayed weak half-cycle pulses reproduce well the experimental data and the solutions of time-dependent Schroedinger equation. When the transferred momenta are stronger and positive, the transition probabilities exhibit fast oscillations with time delay between the pulses. The classical transition probability is constant in time. For negative transferred momenta a focusing phenomenon is observed, and there is a region in time delay, where the transition probabilities oscillate with the Kepler period

Efficient Multiparticle Entanglement via Asymmetric Rydberg Blockade

DEFF Research Database (Denmark)

Saffman, Mark; Mølmer, Klaus

2009-01-01

We present an efficient method for producing N particle entangled states using Rydberg blockade interactions. Optical excitation of Rydberg states that interact weakly, yet have a strong coupling to a second control state is used to achieve state dependent qubit rotations in small ensembles. On t....... On the basis of quantitative calculations, we predict that an entangled quantum superposition state of eight atoms can be produced with a fidelity of 84% in cold Rb atoms.......We present an efficient method for producing N particle entangled states using Rydberg blockade interactions. Optical excitation of Rydberg states that interact weakly, yet have a strong coupling to a second control state is used to achieve state dependent qubit rotations in small ensembles...

Controlling stray electric fields on an atom chip for experiments on Rydberg atoms

Science.gov (United States)

Davtyan, D.; Machluf, S.; Soudijn, M. L.; Naber, J. B.; van Druten, N. J.; van Linden van den Heuvell, H. B.; Spreeuw, R. J. C.

2018-02-01

Experiments handling Rydberg atoms near surfaces must necessarily deal with the high sensitivity of Rydberg atoms to (stray) electric fields that typically emanate from adsorbates on the surface. We demonstrate a method to modify and reduce the stray electric field by changing the adsorbate distribution. We use one of the Rydberg excitation lasers to locally affect the adsorbed dipole distribution. By adjusting the averaged exposure time we change the strength (with the minimal value less than 0.2 V /cm at 78 μ m from the chip) and even the sign of the perpendicular field component. This technique is a useful tool for experiments handling Rydberg atoms near surfaces, including atom chips.

One-Dimensional Rydberg Gas in a Magnetoelectric Trap

International Nuclear Information System (INIS)

Mayle, Michael; Hezel, Bernd; Lesanovsky, Igor; Schmelcher, Peter

2007-01-01

We study the quantum properties of Rydberg atoms in a magnetic Ioffe-Pritchard trap which is superimposed by a homogeneous electric field. Trapped Rydberg atoms can be created in long-lived electronic states exhibiting a permanent electric dipole moment of several hundred Debye. The resulting dipole-dipole interaction in conjunction with the radial confinement is demonstrated to give rise to an effectively one-dimensional ultracold Rydberg gas with a macroscopic interparticle distance. We derive analytical expressions for the electric dipole moment and the required linear density of Rydberg atoms

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

Science.gov (United States)

Dubreuil, B.; Harnafi, M.

1989-07-01

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

Rydberg phases of Hydrogen and low energy nuclear reactions

Science.gov (United States)

Olafsson, Sveinn; Holmlid, Leif

2016-03-01

For over the last 26 years the science of cold fusion/LENR has been researched around the world with slow pace of progress. Modest quantity of excess heat and signatures of nuclear transmutation and helium production have been confirmed in experiments and theoretical work has only resulted in a large flora of inadequate theoretical scenarios. Here we review current state of research in Rydberg matter of Hydrogen that is showing strong signature of nuclear processes. In the presentation experimental behavior of Rydberg matter of hydrogen is described. An extensive collaboration effort of surface physics, catalysis, atomic physics, solid state physics, nuclear physics and quantum information is need to tackle the surprising experimental results that have so far been obtained. Rydberg matter of Hydrogen is the only known state of matter that is able to bring huge collection of protons to so short distances and for so long time that tunneling becomes a reasonable process for making low energy nuclear reactions. Nuclear quantum entanglement can also become realistic process at theses conditions.

Correlated Photon Dynamics in Dissipative Rydberg Media

Science.gov (United States)

Zeuthen, Emil; Gullans, Michael J.; Maghrebi, Mohammad F.; Gorshkov, Alexey V.

2017-07-01

Rydberg blockade physics in optically dense atomic media under the conditions of electromagnetically induced transparency (EIT) leads to strong dissipative interactions between single photons. We introduce a new approach to analyzing this challenging many-body problem in the limit of a large optical depth per blockade radius. In our approach, we separate the single-polariton EIT physics from Rydberg-Rydberg interactions in a serialized manner while using a hard-sphere model for the latter, thus capturing the dualistic particle-wave nature of light as it manifests itself in dissipative Rydberg-EIT media. Using this approach, we analyze the saturation behavior of the transmission through one-dimensional Rydberg-EIT media in the regime of nonperturbative dissipative interactions relevant to current experiments. Our model is able to capture the many-body dynamics of bright, coherent pulses through these strongly interacting media. We compare our model with available experimental data in this regime and find good agreement. We also analyze a scheme for generating regular trains of single photons from continuous-wave input and derive its scaling behavior in the presence of imperfect single-photon EIT.

Revivals of Rydberg wave packets

International Nuclear Information System (INIS)

Bluhm, R.; Kostelecky, V.A.; Tudose, B.

1998-01-01

We examine the revival structure of Rydberg wave packets. These wave packets exhibit initial classical periodic motion followed by a sequence of collapse, fractional (or full) revivals, and fractional (or full) superrevivals. The effects of quantum defects on wave packets in alkali-metal atoms and a squeezed-state description of the initial wave packets are also considered. We then examine the revival structure of Rydberg wave packets in the presence of an external electric field - that is, the revival structure of Stark wave packets. These wave packets have energies that depend on two quantum numbers and exhibit new types of interference behavior

Two electron Rydberg states

International Nuclear Information System (INIS)

Cooke, W.E.

1981-01-01

This paper addresses the study of two-electron Rydberg atoms. With Multichannel Quantum Defect Theory (MQDT), there is a technique for characterizing a spectra in terms of a small number of parameters. A survey of some important effects specific to two-electon Rydberg states, using primarily the alkaline earth atoms for examples, is made. The remainder of the paper deals with a discussion of the electron-electron interaction, including some of the basic points of MQDT. Energy exchange between two electrons is also addressed

Scaling laws of Rydberg excitons

Science.gov (United States)

Heckötter, J.; Freitag, M.; Fröhlich, D.; Aßmann, M.; Bayer, M.; Semina, M. A.; Glazov, M. M.

2017-09-01

Rydberg atoms have attracted considerable interest due to their huge interaction among each other and with external fields. They demonstrate characteristic scaling laws in dependence on the principal quantum number n for features such as the magnetic field for level crossing or the electric field of dissociation. Recently, the observation of excitons in highly excited states has allowed studying Rydberg physics in cuprous oxide crystals. Fundamentally different insights may be expected for Rydberg excitons, as the crystal environment and associated symmetry reduction compared to vacuum give not only optical access to many more states within an exciton multiplet but also extend the Hamiltonian for describing the exciton beyond the hydrogen model. Here we study experimentally and theoretically the scaling of several parameters of Rydberg excitons with n , for some of which we indeed find laws different from those of atoms. For others we find identical scaling laws with n , even though their origin may be distinctly different from the atomic case. At zero field the energy splitting of a particular multiplet n scales as n-3 due to crystal-specific terms in the Hamiltonian, e.g., from the valence band structure. From absorption spectra in magnetic field we find for the first crossing of levels with adjacent principal quantum numbers a Br∝n-4 dependence of the resonance field strength, Br, due to the dominant paramagnetic term unlike for atoms for which the diamagnetic contribution is decisive, resulting in a Br∝n-6 dependence. By contrast, the resonance electric field strength shows a scaling as Er∝n-5 as for Rydberg atoms. Also similar to atoms with the exception of hydrogen we observe anticrossings between states belonging to multiplets with different principal quantum numbers at these resonances. The energy splittings at the avoided crossings scale roughly as n-4, again due to crystal specific features in the exciton Hamiltonian. The data also allow us to

Theoretical Analysis of Rydberg and Autoionizing State Spectra of Antimony

Institute of Scientific and Technical Information of China (English)

Shuang-Fei Lv; Ruohong Li; Feng-Dong Jia; Xiao-Kang Li; Jens Lassen; Zhi-Ping Zhong

2017-01-01

We calculate the Rydberg and autoionization Rydberg spectra of antimony (Sb) from first principles by relativistic multichannel theory within the framework of multichannel quantum defect theory.Our calculation can be used to classify and assign the atomic states described in recently reported three Rydberg series and four autoionizing states.The perturbation effects on line intensity,variation and line profile are discussed.Assignments of the perturber states and autoionizing states are presented.

Coopetition and manipulation of quantum correlations in Rydberg atoms

International Nuclear Information System (INIS)

Fan, Chu-Hui; Yan, Dong; Liu, Yi-Mou; Wu, Jin-Hui

2017-01-01

We study the steady-state quantum correlations arising from the atom–field and interatomic interplays in two-level Rydberg atoms coherently driven by an external laser field. Three kinds of quantum correlations, i.e., atom–atom correlation, atom–field entanglement and photon–photon correlation, are simultaneously examined by considering dipole–dipole interactions (DDI) for pairwise Rydberg atoms. They are shown to be closely linked with single and double Rydberg excitations, which can be modulated to work in the blockade or antiblockade regime depending on the driving field frequency, the DDI strength and the Rydberg decay rate. As a result, we obtain strongly correlated atoms and highly antibunching photons (indispensable resources in applications of quantum information processing) intermediated with robust atom–field entanglement. (paper)

Rydberg-Stark states of Positronium for atom optics

International Nuclear Information System (INIS)

Alonso, A M; Cooper, B S; Deller, A; Hogan, S D; Wall, T E; Cassidy, D B

2015-01-01

Positronium atoms were produced in Rydberg states by means of a two-step optical excitation process (1s→2p→nd/ns). The n = 11 Rydberg-Stark manifold has been studied using different laser polarizations providing greater control over the electric dipole moment. (paper)

Positronium in the AEgIS experiment: study on its emission from nanochanneled samples and design of a new apparatus for Rydberg excitations

CERN Document Server

Di Noto, Lea

This experimental thesis has been done in the framework of AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy), an experiment installed at CERN, whose primary goal is the measurement of the Earth's gravitational acceleration on anti-hydrogen. The antiatoms will be produced by the charge exchange reaction, where a cloud of Ps in Rydberg states interacts with cooled trapped antiprotons. Since the charge exchange cross section depends on Ps velocity and quantum number, the velocity distribution of Ps emitted by a positron-positronium converter as well as its excitation in Rydberg states have to be studied and optimized. In this thesis Ps cooling and emission into vacuum from nanochannelled silicon targets was studied by performing Time of Flight measurements with a dedicated apparatus conceived to receive the slow positron beam as produced at the Trento laboratory or at the NEPOMUC facility at Munich. Measurements were done by varying the positron implantation energy, the sample temperature and ...

GHz Rabi Flopping to Rydberg States in Hot Atomic Vapor Cells

International Nuclear Information System (INIS)

Huber, B.; Baluktsian, T.; Schlagmueller, M.; Koelle, A.; Kuebler, H.; Loew, R.; Pfau, T.

2011-01-01

We report on the observation of Rabi oscillations to a Rydberg state on a time scale below 1 ns in thermal rubidium vapor. We use a bandwidth-limited pulsed excitation and observe up to 6 full Rabi cycles within a pulse duration of ∼4 ns. We find good agreement between the experiment and numerical simulations based on a surprisingly simple model. This result shows that fully coherent dynamics with Rydberg states can be achieved even in thermal atomic vapor, thus suggesting small vapor cells as a platform for room-temperature quantum devices. Furthermore, the result implies that previous coherent dynamics in single-atom Rydberg gates can be accelerated by 3 orders of magnitude.

Resonant inelastic x-ray scattering and photoemission measurement of O2: Direct evidence for dependence of Rydberg-valence mixing on vibrational states in O 1s → Rydberg states

Science.gov (United States)

Gejo, T.; Oura, M.; Tokushima, T.; Horikawa, Y.; Arai, H.; Shin, S.; Kimberg, V.; Kosugi, N.

2017-07-01

High-resolution resonant inelastic x-ray scattering (RIXS) and low-energy photoemission spectra of oxygen molecules have been measured for investigating the electronic structure of Rydberg states in the O 1s → σ* energy region. The electronic characteristics of each Rydberg state have been successfully observed, and new assignments are made for several states. The RIXS spectra clearly show that vibrational excitation is very sensitive to the electronic characteristics because of Rydberg-valence mixing and vibronic coupling in O2. This observation constitutes direct experimental evidence that the Rydberg-valence mixing characteristic depends on the vibrational excitation near the avoided crossing of potential surfaces. We also measured the photoemission spectra of metastable oxygen atoms (O*) from O2 excited to 1s → Rydberg states. The broadening of the 4p Rydberg states of O* has been found with isotropic behavior, implying that excited oxygen molecules undergo dissociation with a lifetime of the order of 10 fs in 1s → Rydberg states.

Theory of long-range interactions for Rydberg states attached to hyperfine-split cores

Science.gov (United States)

Robicheaux, F.; Booth, D. W.; Saffman, M.

2018-02-01

The theory is developed for one- and two-atom interactions when the atom has a Rydberg electron attached to a hyperfine-split core state. This situation is relevant for some of the rare-earth and alkaline-earth atoms that have been proposed for experiments on Rydberg-Rydberg interactions. For the rare-earth atoms, the core electrons can have a very substantial total angular momentum J and a nonzero nuclear spin I . In the alkaline-earth atoms there is a single (s ) core electron whose spin can couple to a nonzero nuclear spin for odd isotopes. The resulting hyperfine splitting of the core state can lead to substantial mixing between the Rydberg series attached to different thresholds. Compared to the unperturbed Rydberg series of the alkali-metal atoms, the series perturbations and near degeneracies from the different parity states could lead to qualitatively different behavior for single-atom Rydberg properties (polarizability, Zeeman mixing and splitting, etc.) as well as Rydberg-Rydberg interactions (C5 and C6 matrices).

Application of the Faddeev-Watson expansion to thermal collisions of Rydberg atoms with neutral particles

International Nuclear Information System (INIS)

de Prunele, E.

1983-01-01

The Faddeev-Watson expansion (FWE) for the T operator is applied to the study of thermal collisions between Rydberg atom and neutral atom. These collisions are considered as a three-body problem (the perturber, the Rydberg electron, and its parent core) and it is assumed, as already done in most theoretical works dealing with Rydberg-atom--atom collisions, that the core-perturber interaction can be neglected. Then the evaluation of the FWE first- and second-order terms is made tractable by using an appropriate separable potential for the Rydberg-electron--perturber interaction. The evaluation of the second-order term allows us to estimate the importance of taking into account explicitly the Rydberg-electron--core interaction in the expression of the (three-body) T operator for the thermal collisions considered. Detailed calculations for the process Rb(n, l = 0)+He →Rb(n',l')+He are presented and discussed. The FWE second-order term has been evaluated for the first time by taking the (two-body) t operator associated with the Rydberg atom (valence electron plus parent core) as the Coulomb potential. The contribution of the FWE second-order term to the scattering amplitude decreases as n increases and is found especially significant when both the momentum transfers involved in the collision are large and the values of l and l' are small

Long-term evolution and revival structure of Rydberg wave packets

International Nuclear Information System (INIS)

Bluhm, R.

1995-01-01

It is known that, after formation, a Rydberg wave packet undergoes a series of collapses and revivals within a time period called the revival time, t rev , at the end of which it is close to its original shape. We study the behavior of Rydberg wave packets on time scales much greater than t rev . We show that after a few revival cycles the wave packet ceases to reform at multiples of the revival time. Instead, a new series of collapses and revivals commences, culminating after a time period t sr >>t rev with the formation of a wave packet that more closely resembles the initial packet than does the full revival at time t rev . Furthermore, at times that are rational fractions of t sr , the square of the autocorrelation function exhibits large peaks with periodicities that can be expressed as fractions of the revival time t rev . These periodicities indicate a new type of fractional revival occurring for times much greater than t rev . A theoretical explanation of these effects is outlined. ((orig.))

Spectroscopy of strontium Rydberg states using electromagnetically induced transparency

International Nuclear Information System (INIS)

Mauger, S; Millen, J; Jones, M P A

2007-01-01

We report on the all-optical detection of Rydberg states in an effusive atomic beam of strontium atoms using electromagnetically induced transparency (EIT). Using narrow-linewidth CW lasers we obtain an EIT linewidth of 5 MHz. To illustrate the high spectroscopic resolution offered by this method, we have measured isotope shifts of the 5s18d 1 D 2 and 5s19s 1 S 0 Rydberg states. This technique could be applied to high-resolution, non-destructive measurements of ultra-cold Rydberg gases and plasmas. (fast track communication)

Evolution from Rydberg gas to ultracold plasma in a supersonic atomic beam of Xe

Science.gov (United States)

Hung, J.; Sadeghi, H.; Schulz-Weiling, M.; Grant, E. R.

2014-08-01

A Rydberg gas of xenon, entrained in a supersonic atomic beam, evolves slowly to form an ultracold plasma. In the early stages of this evolution, when the free-electron density is low, Rydberg atoms undergo long-range \\ell -mixing collisions, yielding states of high orbital angular momentum. The development of high-\\ell states promotes dipole-dipole interactions that help to drive Penning ionization. The electron density increases until it reaches the threshold for avalanche. Ninety μs after the production of a Rydberg gas with the initial state, {{n}_{0}}{{\\ell }_{0}}=42d, a 432 V cm-1 electrostatic pulse fails to separate charge in the excited volume, an effect which is ascribed to screening by free electrons. Photoexcitation cross sections, observed rates of \\ell -mixing, and a coupled-rate-equation model simulating the onset of the electron-impact avalanche point consistently to an initial Rydberg gas density of 5\\times {{10}^{8}}\\;c{{m}^{-3}}.

Self-interaction corrected density functional calculations of molecular Rydberg states

International Nuclear Information System (INIS)

Gudmundsdóttir, Hildur; Zhang, Yao; Weber, Peter M.; Jónsson, Hannes

2013-01-01

A method is presented for calculating the wave function and energy of Rydberg excited states of molecules. A good estimate of the Rydberg state orbital is obtained using ground state density functional theory including Perdew-Zunger self-interaction correction and an optimized effective potential. The total energy of the excited molecule is obtained using the Delta Self-Consistent Field method where an electron is removed from the highest occupied orbital and placed in the Rydberg orbital. Results are presented for the first few Rydberg states of NH 3 , H 2 O, H 2 CO, C 2 H 4 , and N(CH 3 ) 3 . The mean absolute error in the energy of the 33 molecular Rydberg states presented here is 0.18 eV. The orbitals are represented on a real space grid, avoiding the dependence on diffuse atomic basis sets. As in standard density functional theory calculations, the computational effort scales as NM 2 where N is the number of orbitals and M is the number of grid points included in the calculation. Due to the slow scaling of the computational effort with system size and the high level of parallelism in the real space grid approach, the method presented here makes it possible to estimate Rydberg electron binding energy in large molecules

Rydberg energies using excited state density functional theory

International Nuclear Information System (INIS)

Cheng, C.-L.; Wu Qin; Van Voorhis, Troy

2008-01-01

We utilize excited state density functional theory (eDFT) to study Rydberg states in atoms. We show both analytically and numerically that semilocal functionals can give quite reasonable Rydberg energies from eDFT, even in cases where time dependent density functional theory (TDDFT) fails catastrophically. We trace these findings to the fact that in eDFT the Kohn-Sham potential for each state is computed using the appropriate excited state density. Unlike the ground state potential, which typically falls off exponentially, the sequence of excited state potentials has a component that falls off polynomially with distance, leading to a Rydberg-type series. We also address the rigorous basis of eDFT for these systems. Perdew and Levy have shown using the constrained search formalism that every stationary density corresponds, in principle, to an exact stationary state of the full many-body Hamiltonian. In the present context, this means that the excited state DFT solutions are rigorous as long as they deliver the minimum noninteracting kinetic energy for the given density. We use optimized effective potential techniques to show that, in some cases, the eDFT Rydberg solutions appear to deliver the minimum kinetic energy because the associated density is not pure state v-representable. We thus find that eDFT plays a complementary role to constrained DFT: The former works only if the excited state density is not the ground state of some potential while the latter applies only when the density is a ground state density.

Metastability and Rydberg states of triatomic hydrogen

International Nuclear Information System (INIS)

Helm, H.

1991-01-01

The np,nd and nf Rydberg series of H 3 have been studied by one- or two-photon excitation from the lowest metastable state of H 3 :B2p 2 A 2 ''. The lifetime of the metastable state has been measured and the influence of an external electric field on the Rydberg states has been studied under both aspects of dynamics (field-ionization and field-induced predissociation) and structure (Strak effect)

Accurate Mass GC/LC-Quadrupole Time of Flight Mass Spectrometry Analysis of Fatty Acids and Triacylglycerols of Spicy Fruits from the Apiaceae Family

Directory of Open Access Journals (Sweden)

Thao Nguyen

2015-12-01

Full Text Available The triacylglycerol (TAG structure and the regio-stereospecific distribution of fatty acids (FA of seed oils from most of the Apiaceae family are not well documented. The TAG structure ultimately determines the final physical properties of the oils and the position of FAs in the TAG molecule affects the digestion; absorption and metabolism; and physical and technological properties of TAGs. Fixed oils from the fruits of dill (Anethum graveolens, caraway (Carum carvi, cumin (Cuminum cyminum, coriander (Coriandrum sativum, anise (Pimpinella anisum, carrot (Daucus carota, celery (Apium graveolens, fennel (Foeniculum vulgare, and Khella (Ammi visnaga, all from the Apiaceae family, were extracted at room temperature in chloroform/methanol (2:1 v/v using percolators. Crude lipids were fractionated by solid phase extraction to separate neutral triacylglycerols (TAGs from other lipids components. Neutral TAGs were subjected to transesterification process to convert them to their corresponding fatty acids methyl esters (FAMES using 1% boron trifluoride (BF3 in methanol. FAMES were analyzed by gas chromatography-quadrupole time of flight (GC-QTOF mass spectrometry. Triglycerides were analyzed using high performance liquid chromatography-quadrupole time of flight (LC-QTOF mass spectrometry. Petroselinic acid was the major fatty acid in all samples ranging from 57% of the total fatty acids in caraway up to 82% in fennel. All samples contained palmitic (16:0, palmitoleic (C16:1n-9, stearic (C18:0, petroselinic (C18:1n-12, linoleic (C18:2n-6, linolinic (18:3n-3, and arachidic (C20:0 acids. TAG were analyzed using LC-QTOF for accurate mass identification and mass spectrometry/mass spectrometry (MS/MS techniques for regiospesific elucidation of the identified TAGs. Five major TAGs were detected in all samples but with different relative concentrations in all of the tested samples. Several other TAGs were detected as minor components and were present in some

D-state Rydberg electrons interacting with ultracold atoms

Energy Technology Data Exchange (ETDEWEB)

Krupp, Alexander Thorsten

2014-10-02

This thesis was established in the field of ultracold atoms where the interaction of highly excited D-state electrons with rubidium atoms was examined. This work is divided into two main parts: In the first part we study D-state Rydberg molecules resulting from the binding of a D-state Rydberg electron to a ground state rubidium atom. We show that we can address specific rovibrational molecular states by changing our laser detuning and thus create perfectly aligned axial or antialigned toroidal molecules, in good agreement with our theoretical calculations. Furthermore the influence of the electric field on the Rydberg molecules was investigated, creating novel states which show a different angular dependence and alignment. In the second part of this thesis we excite single D-state Rydberg electrons in a Bose-Einstein condensate. We study the lifetime of these Rydberg electrons, the change of the shape of our condensate and the atom losses in the condensate due to this process. Moreover, we observe quadrupolar shape oscillations of the whole condensate created by the consecutive excitation of Rydberg atoms and compare all results to previous S-state measurements. In the outlook we propose a wide range of further experiments including the proposal of imaging a single electron wavefunction by the imprint of its orbit into the Bose-Einstein condensate.

Wave packet fractional revivals in a one-dimensional Rydberg atom

International Nuclear Information System (INIS)

Veilande, Rita; Bersons, Imants

2007-01-01

We investigate many characteristic features of revival and fractional revival phenomena via derived analytic expressions for an autocorrelation function of a one-dimensional Rydberg atom with weighting probabilities modelled by a Gaussian or a Lorentzian distribution. The fractional revival phenomenon in the ionization probabilities of a one-dimensional Rydberg atom irradiated by two short half-cycle pulses is also studied. When many states are involved in the formation of the wave packet, the revival is lower and broader than the initial wave packet and the fractional revivals overlap and disappear with time

Many-body physics with alkaline-earth Rydberg lattices

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, R; Nath, R; Pohl, T [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, 01187 Dresden (Germany); Millen, J; Jones, M P A, E-mail: rick@pks.mpg.de [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)

2011-09-28

We explore the prospects for confining alkaline-earth Rydberg atoms in an optical lattice via optical dressing of the secondary core-valence electron. Focussing on the particular case of strontium, we identify experimentally accessible magic wavelengths for simultaneous trapping of ground and Rydberg states. A detailed analysis of relevant loss mechanisms shows that the overall lifetime of such a system is limited only by the spontaneous decay of the Rydberg state, and is not significantly affected by photoionization or autoionization. The van der Waals C{sub 6} coefficients for the Sr(5sns {sup 1}S{sub 0}) Rydberg series are calculated, and we find that the interactions are attractive. Finally we show that the combination of magic-wavelength lattices and attractive interactions could be exploited to generate many-body Greenberger-Horne-Zeilinger states.

High resolution studies of barium Rydberg states

International Nuclear Information System (INIS)

Eliel, E.R.

1982-01-01

The subtle structure of Rydberg states of barium with orbital angular momentum 0, 1, 2 and 3 is investigated. Some aspects of atomic theory for a configuration with two valence electrons are reviewed. The Multi Channel Quantum Defect Theory (MQDT) is concisely introduced as a convenient way to describe interactions between Rydberg series. Three high-resolution UV studies are presented. The first two, presenting results on a transition in indium and europium serve as an illustration of the frequency doubling technique. The third study is of hyperfine structure and isotope shifts in low-lying p states in Sr and Ba. An extensive study of the 6snp and 6snf Rydberg states of barium is presented with particular emphasis on the 6snf states. It is shown that the level structure cannot be fully explained with the model introduced earlier. Rather an effective two-body spin-orbit interaction has to be introduced to account for the observed splittings, illustrating that high resolution studies on Rydberg states offer an unique opportunity to determine the importance of such effects. Finally, the 6sns and 6snd series are considered. The hyperfine induced isotope shift in the simple excitation spectra to 6sns 1 S 0 is discussed and attention is paid to series perturbers. It is shown that level mixing parameters can easily be extracted from the experimental data. (Auth.)

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

Quantum information with Rydberg atoms

DEFF Research Database (Denmark)

Saffman, Mark; Walker, T.G.; Mølmer, Klaus

2010-01-01

Rydberg atoms with principal quantum number n»1 have exaggerated atomic properties including dipole-dipole interactions that scale as n4 and radiative lifetimes that scale as n3. It was proposed a decade ago to take advantage of these properties to implement quantum gates between neutral atom...... of multiqubit registers, implementation of robust light-atom quantum interfaces, and the potential for simulating quantum many-body physics. The advances of the last decade are reviewed, covering both theoretical and experimental aspects of Rydberg-mediated quantum information processing....

Quantum localization in the three-dimensional kicked Rydberg atom

International Nuclear Information System (INIS)

Persson, Emil; Yoshida, Shuhei; Burgdoerfer, Joachim; Tong, X.-M.; Reinhold, Carlos O.

2003-01-01

We study the three-dimensional (3D) unidirectionally kicked Rydberg atom. For parabolic initial states elongated in the direction of the kicks we show that the ionization of the quantum system is suppressed as compared to the classical counterpart and that the quantum wave function is localized along all degrees of freedom, whereas the classical system is globally diffusive. We discuss the connection to the previously studied one-dimensional (1D) model of the kicked Rydberg atom and verify that the 1D model is a good approximation to the 3D quantum case in the limiting case of the most elongated initial states. We further study the quantum phase-space distribution (Husimi distribution) of the eigenstates of the period-one time-evolution (Floquet) operator and show that the eigenstates are localized in phase space. For the most elongated parabolic initial state, we are able to identify the unstable periodic orbits around which Floquet states localize. We discuss the possibility of observing quantum localization in high Rydberg states in n>100

Ionization of Rydberg atoms by the kicks of half-cycle pulses

Indian Academy of Sciences (India)

Rydberg atom; half-cycle pulses; ionization; quantum mechanical model. ... packet which represents a non-stationary quantum state formed by coherent ...... Wetzels, Impulsive interactions of half cycle pulse radiation with Rydberg atoms, Ph.D.

Rydberg states of chloroform studied by VUV photoabsorption spectroscopy

International Nuclear Information System (INIS)

Singh, Param Jeet; Shastri, Aparna; D’Souza, R.; Jagatap, B.N.

2013-01-01

The VUV photoabsorption spectra of CHCl 3 and CDCl 3 in the energy region 6.2–11.8 eV (50,000–95,000 cm −1 ) have been investigated using synchrotron radiation from the Indus-1 source. Rydberg series converging to the first four ionization limits at 11.48, 11.91, 12.01 and 12.85 eV corresponding to excitation from the 1a 2 , 4a 1 , 4e, 3e, orbitals of CHCl 3 respectively are identified and analyzed. Quantum defect values are observed to be consistent with excitation from the chlorine lone pair orbitals. Vibrational progressions observed in the region of 72,500–76,500 cm −1 have been reassigned to ν 3 and combination modes of ν 3 +ν 6 belonging to the 1a 2 →4p transition in contrast to earlier studies where they were assigned to a ν 3 progression superimposed on the 3e→4p Rydberg transition. The assignments are further confirmed based on isotopic substitution studies on CDCl 3 whose VUV photoabsorption spectrum is reported here for the first time. The frequencies of the ν 3 and ν 6 modes in the 4p Rydberg state of CHCl 3 (CDCl 3 ) are proposed to be ∼454 (409) cm −1 and∼130 (129) cm −1 respectively based on the vibronic analysis. DFT calculations of neutral and ionic ground state vibrational frequencies support the vibronic analysis. Experimental spectrum is found to be in good agreement with that predicted by TDDFT calculations. This work presents a consolidated analysis of the VUV photoabsorption spectrum of chloroform. -- Highlights: •VUV photoabsorption spectra of CHCl 3 and CDCl 3 studied using synchrotron radiation. •Quantum defect analysis of Rydberg series converging to first four ionization limits. •Vibronic bands in 72,500–76,500 cm −1 region assigned to 1a 2 →4p Rydberg transition. •Vibrational progressions assigned to ν 3 and ν 3 +ν 6 using ab initio calculations. •Excellent agreement of TDDFT vertical excited energies with experimental spectrum

Survival of Rydberg atoms in intense laser fields and the role of nondipole effects

Science.gov (United States)

Klaiber, Michael; Dimitrovski, Darko

2015-02-01

We consider the interaction of Rydberg atoms with strong infrared laser pulses using an approach based on the Magnus expansion of the time evolution operator. First-order corrections beyond the electric dipole approximation are also included in the theory. We illustrate the dynamics of the interaction at the parameters of the experiment [Eichmann et al., Phys. Rev. Lett. 110, 203002 (2013), 10.1103/PhysRevLett.110.203002]. It emerges that the depletion of Rydberg atoms in this regime comes predominantly from the nondipole effects.

Ionization Spectroscopic Measurement of nP Rydberg Levels of 87Rb Cold Atoms

Science.gov (United States)

Li, Yufan; Zaheeruddin, Syed; Zhao, Dongmei; Ma, Xinwen; Yang, Jie

2018-05-01

We created an ultracold plasma via the spontaneous ionization of cold dense Rydberg atoms of 87Rb in a magneto-optical trap (MOT), and measured the nS1/2 (n = 50-80), nP1/2 (n = 16-23), nP3/2 (n = 16-98), and nD5/2 (n = 49-96) Rydberg levels by detecting the electrons in the ultracold plasma. By fitting the energy levels of Rydberg states, the first ionization potential of 33690.950(11) cm-1 and the quantum defects of S, P, and D orbitals were obtained. The absolute transition energies of nS1/2 (n = 66-80), nP1/2 (n = 16-23), nP3/2 (n = 16-98), and nD5/2 (n = 58-96) states of 87Rb, as well as the quantum defects for p1/2 and p3/2 series, are given for the first time.

Jahn-Teller effect in Rydberg series: A multi-state vibronic coupling problem

International Nuclear Information System (INIS)

Staib, A.; Domcke, W.; Sobolewski, A.L.

1990-01-01

Two simple limiting cases of Jahn-Teller (JT) coupling in Rydberg states of polyatomic molecules are considered, namely (i) JT coupling in Rydberg orbitals as well as in the ionization continuum (nondegenerate ion core, degenerate Rydberg series) and (ii) JT coupling in the ion core (degenerate ion core, nondegenerate Rydberg series). For both models simple and efficient algorithms for the computation of spectra (dynamical JT effect) are developed. The orbital JT effect is shown to represent a novel type of multi-state vibronic coupling, giving rise to interesting spectroscopic phenomena, among them resonant inter-Rydberg perturbations and JT induced autoionization. Particular attention is paid to the demonstration of the characteristic spectroscopic signatures of the two types of JT coupling in Rydberg states. (orig.)

Rydberg atoms ionization by microwave field and electromagnetic pulses

International Nuclear Information System (INIS)

Kaulakys, B.; Vilutis, G.

1995-01-01

A simple theory of the Rydberg atoms ionization by electromagnetic pulses and microwave field is presented. The analysis is based on the scale transformation which reduces the number of parameters and reveals the functional dependencies of the processes. It is shown that the observed ionization of Rydberg atoms by subpicosecond electromagnetic pulses scale classically. The threshold electric field required to ionise a Rydberg state may be simply evaluated in the photonic basis approach for the quantum dynamics or from the multiphoton ionization theory

Postprandial phase time influences the uptake of TAG from postprandial TAG-rich lipoproteins by THP-1 macrophages.

Science.gov (United States)

Cabello-Moruno, Rosana; Sinausia, Laura; Botham, Kathleen M; Montero, Emilio; Avella, Michael; Perona, Javier S

2014-11-14

Postprandial TAG-rich lipoproteins (TRL) can be taken up by macrophages, leading to the formation of foam cells, probably via receptor-mediated pathways. The present study was conducted to investigate whether the postprandial time point at which TRL are collected modulates this process. A meal containing refined olive oil was given to nine healthy young men and TRL were isolated from their serum at 2, 4 and 6 h postprandially. The lipid class and apoB compositions of TRL were determined by HPLC and SDS-PAGE, respectively. The accumulation of lipids in macrophages was determined after the incubation of THP-1 macrophages with TRL. The gene expression of candidate receptors was measured by real-time PCR. The highest concentrations of TAG, apoB48 and apoB100 in TRL were observed at 2 h after the consumption of the test meal. However, excessive intracellular TAG accumulation in THP-1 macrophages was observed in response to incubation with TRL isolated at 4 h, when their particle size (estimated as the TAG:apoB ratio) was intermediate. The abundance of mRNA transcripts in macrophages in response to incubation with TRL was down-regulated for LDL receptor (LDLR), slightly up-regulated for VLDL receptor and remained unaltered for LDLR-related protein, but no effect of the postprandial time point was observed. In contrast, the mRNA expression of scavenger receptors SRB1, SRA2 and CD36 was higher when cells were incubated with TRL isolated at 4 h after the consumption of the test meal. In conclusion, TRL led to excessive intracellular TAG accumulation in THP-1 macrophages, which was greater when cells were incubated with intermediate-sized postprandial TRL isolated at 4 h and was associated with a significant increase in the mRNA expression of scavenger receptors.

Contaminant-State Broadening Mechanism in a Driven Dissipative Rydberg System

Science.gov (United States)

Porto, J. V.

2017-04-01

The strong interactions in Rydberg atoms make them an ideal system for the study of correlated many-body physics, both in the presence and absence of dissipation. Using such highly excited atomic states requires addressing challenges posed by the dense spectrum of Rydberg levels, the detrimental effects of spontaneous emission, and strong interactions. A full understanding of the scope and limitations of many Rydberg-based proposals requires simultaneously including these effects, which typically cannot be described by a mean-field treatment due to correlations in the quantum coherent and dissipative processes. We study a driven, dissipative system of Rydberg atoms in a 3D optical lattice, and observe substantial deviation from single-particle excitation rates, both on and off resonance. The observed broadened spectra cannot be explained by van der Waals interactions or a mean-field treatment of the system. Based on the magnitude of the broadening and the scaling with density and two-photon Rabi frequency, we attribute these effects to unavoidable blackbody-induced transitions to nearby Rydberg states of opposite parity, which have large, resonant dipole-dipole interactions with the state of interest. Even at low densities of Rydberg atoms, uncontrolled production of atoms in other states significantly modifies the energy levels of the remaining atoms. These off-diagonal exchange interactions result in complex many-body states of the system and have implications for off-resonant Rydberg dressing proposals. This work was partially supported by the ARL-CDQI program.

Activity on improving performance of time-of-flight detector at CDF

International Nuclear Information System (INIS)

Menzione, A.; Cerri, C.; Vataga, E.; Prokoshin, F.; Tokar, S.

2002-01-01

The paper describes activity on improving the time resolution of the Time-of-Flight detector at CDF. The main goal of the detector is the identification of kaons and pions for b-quark (B-meson) flavour tagging. Construction of the detector has been described as well as proposals on detector design changes to improve its time resolution. Monte Carlo simulation of the detector response to MIP was performed. The results of the simulation showed that the proposed modifications (at least with currently available materials) bring modest or no improvement of the detector time resolution. An automated set-up was assembled to test and check out the changes in the electronic readout system of the detector. Sophisticated software has been developed for this set-up to provide control of the system as well as processing and presentation of data from the detector. This software can perform various tests using different implementations of the hardware set-up

Microscopic Characterization of Scalable Coherent Rydberg Superatoms

Directory of Open Access Journals (Sweden)

Johannes Zeiher

2015-08-01

Full Text Available Strong interactions can amplify quantum effects such that they become important on macroscopic scales. Controlling these coherently on a single-particle level is essential for the tailored preparation of strongly correlated quantum systems and opens up new prospects for quantum technologies. Rydberg atoms offer such strong interactions, which lead to extreme nonlinearities in laser-coupled atomic ensembles. As a result, multiple excitation of a micrometer-sized cloud can be blocked while the light-matter coupling becomes collectively enhanced. The resulting two-level system, often called a “superatom,” is a valuable resource for quantum information, providing a collective qubit. Here, we report on the preparation of 2 orders of magnitude scalable superatoms utilizing the large interaction strength provided by Rydberg atoms combined with precise control of an ensemble of ultracold atoms in an optical lattice. The latter is achieved with sub-shot-noise precision by local manipulation of a two-dimensional Mott insulator. We microscopically confirm the superatom picture by in situ detection of the Rydberg excitations and observe the characteristic square-root scaling of the optical coupling with the number of atoms. Enabled by the full control over the atomic sample, including the motional degrees of freedom, we infer the overlap of the produced many-body state with a W state from the observed Rabi oscillations and deduce the presence of entanglement. Finally, we investigate the breakdown of the superatom picture when two Rydberg excitations are present in the system, which leads to dephasing and a loss of coherence.

High Angular Momentum Rydberg Wave Packets

Science.gov (United States)

Wyker, Brendan

2011-12-01

High angular momentum Rydberg wave packets are studied. Application of carefully tailored electric fields to low angular momentum, high- n (n ˜ 300) Rydberg atoms creates coherent superpositions of Stark states with near extreme values of angular momentum, ℓ. Wave packet components orbit the parent nucleus at rates that depend on their energy, leading to periods of localization and delocalization as the components come into and go out of phase with each other. Monitoring survival probability signals in the presence of position dependent probing leads to observation of characteristic oscillations based on the composition of the wave packet. The discrete nature of electron energy levels is observed through the measurement of quantum revivals in the wave packet localization signal. Time-domain spectroscopy of these signals allows determination of both the population and phase of individual superposition components. Precise manipulation of wave packets is achieved through further application of pulsed electric fields. Decoherence effects due to background gas collisions and electrical noise are also detailed. Quantized classical trajectory Monte-Carlo simulations are introduced and agree remarkably well with experimental results.

Interactions of circular Rydberg atoms with charged particles

International Nuclear Information System (INIS)

Wang, J.

1994-01-01

Recent progress in experimental cross-field techniques has made it possible to produce oriented Rydberg atoms of any angular momentum l within a given n manifold. The largest angular momentum state l max = n - 1 of a given n manifold is of particular interest because of its semiclassical properties for n much-gt 1. The corresponding classical Kepler orbit is circular with highly localized phase space distribution. The circular Rydberg atoms afford the opportunity to study various interactions in the semiclassical regime. The authors report electron capture from circular Rydberg atoms by protons and positrons at speeds comparable to the electron orbital speed. They find orientation dependent, novel peak structures for both protons and positrons in the angular scattering of the particles. The structures may be understood in terms of quasi Thomas double scattering mechanism for capture. Other related aspects including final state population and orientation indulged scattering asymmetry will also be discussed

Observation of pendular butterfly Rydberg molecules

Science.gov (United States)

Niederprüm, Thomas; Thomas, Oliver; Eichert, Tanita; Lippe, Carsten; Pérez-Ríos, Jesús; Greene, Chris H.; Ott, Herwig

2016-01-01

Engineering molecules with a tunable bond length and defined quantum states lies at the heart of quantum chemistry. The unconventional binding mechanism of Rydberg molecules makes them a promising candidate to implement such tunable molecules. A very peculiar type of Rydberg molecules are the so-called butterfly molecules, which are bound by a shape resonance in the electron–perturber scattering. Here we report the observation of these exotic molecules and employ their exceptional properties to engineer their bond length, vibrational state, angular momentum and orientation in a small electric field. Combining the variable bond length with their giant dipole moment of several hundred Debye, we observe counter-intuitive molecules which locate the average electron position beyond the internuclear distance. PMID:27703143

Time Series Neural Network Model for Part-of-Speech Tagging Indonesian Language

Science.gov (United States)

Tanadi, Theo

2018-03-01

Part-of-speech tagging (POS tagging) is an important part in natural language processing. Many methods have been used to do this task, including neural network. This paper models a neural network that attempts to do POS tagging. A time series neural network is modelled to solve the problems that a basic neural network faces when attempting to do POS tagging. In order to enable the neural network to have text data input, the text data will get clustered first using Brown Clustering, resulting a binary dictionary that the neural network can use. To further the accuracy of the neural network, other features such as the POS tag, suffix, and affix of previous words would also be fed to the neural network.

Creating high-purity angular-momentum-state Rydberg atoms by a pair of unipolar laser pulses

Science.gov (United States)

Xin, PeiPei; Cheng, Hong; Zhang, ShanShan; Wang, HanMu; Xu, ZiShan; Liu, HongPing

2018-04-01

We propose a method of producing high-purity angular-momentum-state Rydberg atoms by a pair of unipolar laser pulses. The first positive-polarity optical half-cycle pulse is used to prepare an excited-state wave packet while the second one is less intense, but with opposite polarity and time delayed, and is employed to drag back the escaping free electron and clip the shape of the bound Rydberg wave packet, selectively increasing or decreasing a fraction of the angular-momentum components. An intelligent choice of laser parameters such as phase and amplitude helps us to control the orbital-angular-momentum composition of an electron wave packet with more facility; thus, a specified angular-momentum state with high purity can be achieved. This scheme of producing high-purity angular-momentum-state Rydberg atoms has significant application in quantum-information processing.

Dynamics of Rydberg atom lattices in the presence of noise and dissipation

International Nuclear Information System (INIS)

Abdussalam, Wildan

2017-01-01

The work presented in this dissertation concerns dynamics of Rydberg atom lattices in the presence of noise and dissipation. Rydberg atoms possess a number of exaggerated properties, such as a strong van der Waals interaction. The interplay of that interaction, coherent driving and decoherence leads to intriguing non-equilibrium phenomena. Here, we study the non-equilibrium physics of driven atom lattices in the presence of decoherence caused by either laser phase noise or strong decay. In the first case, we compare between global and local noise and explore their effect on the number of excitations and the full counting statistics. We find that both types of noise give rise to a characteristic distribution of the Rydberg excitation number. The main method employed is the Langevin equation but for the sake of efficiency in certain regimes, we use a Markovian master equation and Monte Carlo rate equations, respectively. In the second case, we consider dissipative systems with more general power-law interactions. We determine the phase diagram in the steady state and analyse its generation dynamics using Monte Carlo rate equations. In contrast to nearest-neighbour models, there is no transition to long-range-ordered phases for realistic interactions and resonant driving. Yet, for finite laser detunings, we show that Rydberg atom lattices can undergo a dissipative phase transition to a long-range-ordered antiferromagnetic phase. We identify the advantages of Monte Carlo rate equations over mean field predictions. Having studied the dynamics of Rydberg atom lattices, we study an application of the strong interactions in such systems for quantum information processing. We investigate the coherent exchange of a single photon between a superconducting microwave cavity and a lattice of strongly interacting Rydberg atoms in the presence of local electric field fluctuations plaguing the cavity surface. We show that despite the increased sensitivity of Rydberg states to

Dynamics of Rydberg atom lattices in the presence of noise and dissipation

Energy Technology Data Exchange (ETDEWEB)

Abdussalam, Wildan

2017-08-07

The work presented in this dissertation concerns dynamics of Rydberg atom lattices in the presence of noise and dissipation. Rydberg atoms possess a number of exaggerated properties, such as a strong van der Waals interaction. The interplay of that interaction, coherent driving and decoherence leads to intriguing non-equilibrium phenomena. Here, we study the non-equilibrium physics of driven atom lattices in the presence of decoherence caused by either laser phase noise or strong decay. In the first case, we compare between global and local noise and explore their effect on the number of excitations and the full counting statistics. We find that both types of noise give rise to a characteristic distribution of the Rydberg excitation number. The main method employed is the Langevin equation but for the sake of efficiency in certain regimes, we use a Markovian master equation and Monte Carlo rate equations, respectively. In the second case, we consider dissipative systems with more general power-law interactions. We determine the phase diagram in the steady state and analyse its generation dynamics using Monte Carlo rate equations. In contrast to nearest-neighbour models, there is no transition to long-range-ordered phases for realistic interactions and resonant driving. Yet, for finite laser detunings, we show that Rydberg atom lattices can undergo a dissipative phase transition to a long-range-ordered antiferromagnetic phase. We identify the advantages of Monte Carlo rate equations over mean field predictions. Having studied the dynamics of Rydberg atom lattices, we study an application of the strong interactions in such systems for quantum information processing. We investigate the coherent exchange of a single photon between a superconducting microwave cavity and a lattice of strongly interacting Rydberg atoms in the presence of local electric field fluctuations plaguing the cavity surface. We show that despite the increased sensitivity of Rydberg states to

Many-body dynamics of holes in a driven, dissipative spin chain of Rydberg superatoms

Science.gov (United States)

Letscher, Fabian; Petrosyan, David; Fleischhauer, Michael

2017-11-01

Strong, long-range interactions between atoms in high-lying Rydberg states can suppress multiple Rydberg excitations within a micron-sized trapping volume and yield sizable Rydberg level shifts at larger distances. Ensembles of atoms in optical microtraps then form Rydberg superatoms with collectively enhanced transition rates to the singly excited state. These superatoms can represent mesoscopic, strongly interacting spins. We study a regular array of such effective spins driven by a laser field tuned to compensate the interaction-induced level shifts between neighboring superatoms. During the initial transient, a few excited superatoms seed a cascade of resonantly facilitated excitation of large clusters of superatoms. Due to spontaneous decay, the system then relaxes to the steady state having nearly universal Rydberg excitation density {ρ }{{R}}=2/3. This state is characterized by highly non-trivial equilibrium dynamics of quasi-particles—excitation holes in the lattice of Rydberg excited superatoms. We derive an effective many-body model that accounts for hole mobility as well as continuous creation and annihilation of holes upon collisions with each other. We find that holes exhibit a nearly incompressible liquid phase with highly sub-Poissonian number statistics and finite-range density-density correlations.

Modeling the tagged-neutron UXO identification technique using the Geant4 toolkit

International Nuclear Information System (INIS)

Zhou, Y.; Zhu, X.; Wang, Y.; Mitra, S.

2012-01-01

It is proposed to use 14 MeV neutrons tagged by the associated particle neutron time-of-flight technique (APnTOF) to identify the fillers of unexploded ordnances (UXO) by characterizing their carbon, nitrogen and oxygen contents. To facilitate the design and construction of a prototype system, a preliminary simulation model was developed, using the Geant4 toolkit. This work established the toolkit environment for (a) generating tagged neutrons, (b) their transport and interactions within a sample to induce emission and detection of characteristic gamma-rays, and (c) 2D and 3D-image reconstruction of the interrogated object using the neutron and gamma-ray time-of-flight information. Using the modeling, this article demonstrates the novelty of the tagged-neutron approach for extracting useful signals with high signal-to-background discrimination of an object-of-interest from that of its environment. Simulations indicated that an UXO filled with the RDX explosive, hexogen (C 3 H 6 O 6 N 6 ), can be identified to a depth of 20 cm when buried in soil. (author)

Investigation by high resolution electron spectroscopy of the helium-like 3lnl' Rydberg series in double capture processes at low collision velocity: auto transfer to Rydberg states and electron stabilization

International Nuclear Information System (INIS)

Bordenave-Montesquieu, A.; Moretto-Capelle, P.; Gonzalez, A.; Benhenni, M.; Bachau, H.; Sanchez, I.

1994-01-01

A high resolution electron spectrometry of the (3lnl') Ryberg series populated in N 7+ + He and Ne 10+ + He collisions at 10 q keV, 10 o allows us to observe, for the first time by this method, two post-collisional effects. First, it is found with nitrogen ions that, when n increases from n = 4 to 9, the L-distribution peaks more and more on the high angular momentum states. This is qualitatively understood as a Stark deformation of the Rydberg orbit by the Coulomb field of the receding ion. Also, in the n range where the double capture process populates symmetrical 4l4l' states (n>9), an enhancement of the intensities of the 3lnl' Rydberg lines is observed for both collisonal systems. This is thought to be a signature of the so-called auto transfer to Rydberg states effect. The transfer of population from the 3l4l' to the 3lnl' states is found to be favoured against a direct autoionization of these 4l4l' states into the n = 2 continuum. These experimental findings together with preliminary spectroscopic calculations concerning the configuration interaction of the Ne 8+ (4l4l') states with the Ne 8+ (3lnl') Rydberg series are also discussed within the context of the electron stabilization which follows a double capture. (Author)

Semiclassical calculation of ionisation rate for Rydberg helium atoms in an electric field

International Nuclear Information System (INIS)

Wang De-Hua

2011-01-01

The ionisation of Rydberg helium atoms in an electric field above the classical ionisation threshold has been examined using the semiclassical method, with particular emphasis on discussing the influence of the core scattering on the escape dynamics of electrons. The results show that the Rydberg helium atoms ionise by emitting a train of electron pulses. Unlike the case of the ionisation of Rydberg hydrogen atom in parallel electric and magnetic fields, where the pulses of the electron are caused by the external magnetic field, the pulse trains for Rydberg helium atoms are created through core scattering. Each peak in the ionisation rate corresponds to the contribution of one core-scattered combination trajectory. This fact further illustrates that the ionic core scattering leads to the chaotic property of the Rydberg helium atom in external fields. Our studies provide a simple explanation for the escape dynamics in the ionisation of nonhydrogenic atoms in external fields. (atomic and molecular physics)

Non-adiabatic quantum state preparation and quantum state transport in chains of Rydberg atoms

Science.gov (United States)

Ostmann, Maike; Minář, Jiří; Marcuzzi, Matteo; Levi, Emanuele; Lesanovsky, Igor

2017-12-01

Motivated by recent progress in the experimental manipulation of cold atoms in optical lattices, we study three different protocols for non-adiabatic quantum state preparation and state transport in chains of Rydberg atoms. The protocols we discuss are based on the blockade mechanism between atoms which, when excited to a Rydberg state, interact through a van der Waals potential, and rely on single-site addressing. Specifically, we discuss protocols for efficient creation of an antiferromagnetic GHZ state, a class of matrix product states including a so-called Rydberg crystal and for the state transport of a single-qubit quantum state between two ends of a chain of atoms. We identify system parameters allowing for the operation of the protocols on timescales shorter than the lifetime of the Rydberg states while yielding high fidelity output states. We discuss the effect of positional disorder on the resulting states and comment on limitations due to other sources of noise such as radiative decay of the Rydberg states. The proposed protocols provide a testbed for benchmarking the performance of quantum information processing platforms based on Rydberg atoms.

The role of Rydberg and continuum levels in computing high harmonic generation spectra of the hydrogen atom using time-dependent configuration interaction

International Nuclear Information System (INIS)

Luppi, Eleonora; Head-Gordon, Martin

2013-01-01

We study the role of Rydberg bound-states and continuum levels in the field-induced electronic dynamics associated with the High-Harmonic Generation (HHG) spectroscopy of the hydrogen atom. Time-dependent configuration-interaction (TD-CI) is used with very large atomic orbital (AO) expansions (up to L= 4 with sextuple augmentation and off-center functions) to describe the bound Rydberg levels, and some continuum levels. To address the lack of ionization losses in TD-CI with finite AO basis sets, we employed a heuristic lifetime for energy levels above the ionization potential. The heuristic lifetime model is compared against the conventional atomic orbital treatment (infinite lifetimes), and a third approximation which is TD-CI using only the bound levels (continuum lifetimes go to zero). The results suggest that spectra calculated using conventional TD-CI do not converge with increasing AO basis set size, while the zero lifetime and heuristic lifetime models converge to qualitatively similar spectra, with implications for how best to apply bound state electronic structure methods to simulate HHG. The origin of HHG spectral features including the cutoff and extent of interference between peaks is uncovered by separating field-induced coupling between different types of levels (ground state, bound Rydberg levels, and continuum) in the simulated electronic dynamics. Thus the origin of deviations between the predictions of the semi-classical three step model and the full simulation can be associated with particular physical contributions, which helps to explain both the successes and the limitations of the three step model

MgH Rydberg series: Transition energies from electron propagator theory and oscillator strengths from the molecular quantum defect orbital method

Science.gov (United States)

Corzo, H. H.; Velasco, A. M.; Lavín, C.; Ortiz, J. V.

2018-02-01

Vertical excitation energies belonging to several Rydberg series of MgH have been inferred from 3+ electron-propagator calculations of the electron affinities of MgH+ and are in close agreement with experiment. Many electronically excited states with n > 3 are reported for the first time and new insight is given on the assignment of several Rydberg series. Valence and Rydberg excited states of MgH are distinguished respectively by high and low pole strengths corresponding to Dyson orbitals of electron attachment to the cation. By applying the Molecular Quantum Defect Orbital method, oscillator strengths for electronic transitions involving Rydberg states also have been determined.

Autoionizing np Rydberg states of H2

International Nuclear Information System (INIS)

Xu, E.Y.; Helm, H.; Kachru, R.

1989-01-01

We report a study of the autoionizing np Rydberg states near the lowest ionization threshold of H 2 . Using resonant two-photon excitation, intermediate states in specific rotovibrational levels in the double well, E,F 1 Σ/sub g/ + states are prepared. Then, a second, tunable laser is used to photoionize via excitation of the np Rydberg states. Because of the stepwise laser excitation scheme employed in our experiment the photoionization occurs from states with vibrational wave functions very similar to those of the H 2 + core. As a consequence, the autoionizing states appear as nearly symmetric resonances, rather than the highly asymmetric Beutler-Fano profiles observed from the direct photoexcitation from the ground state of H 2 . Our experiments show that the J = 1 np states are broader than the J = 3 np states converging to the same limit, suggesting that the two states autoionize into the epsilon-cp and epsilon-cf continuum, respectively. We compare our observations with a theoretical analysis using a multichannel quantum defect theory. The J = 1 states reveal the profound effect caused by the perturbation of the autoionizing Rydberg series converging to the lowest vibrational and rotational state of H 2 + by low-n states converging to higher vibrational states of the H 2 -ion core

Radiative lifetime measurements of rubidium Rydberg states

International Nuclear Information System (INIS)

Branden, D B; Juhasz, T; Mahlokozera, T; Vesa, C; Wilson, R O; Zheng, M; Tate, D A; Kortyna, A

2010-01-01

We have measured the radiative lifetimes of ns, np and nd Rydberg states of rubidium in the range 28 ≤ n ≤ 45. To enable long-lived states to be measured, our experiment uses slow-moving (∼100 μK) 85 Rb atoms in a magneto-optical trap (MOT). Two experimental techniques have been adopted to reduce random and systematic errors. First, a narrow-bandwidth pulsed laser is used to excite the target nl Rydberg state, resulting in minimal shot-to-shot variation in the initial state population. Second, we monitor the target state population as a function of time delay from the laser pulse using a short-duration, millimetre-wave pulse that is resonant with a one- or two-photon transition to a higher energy 'monitor state', n'l'. We then selectively field ionize the monitor state, and detect the resulting electrons with a micro-channel plate. This signal is an accurate mirror of the nl target state population, and is uncontaminated by contributions from other states which are populated by black body radiation. Our results are generally consistent with other recent experimental results obtained using a method which is more prone to systematic error, and are also in excellent agreement with theory.

Rydberg dressing of atoms in optical lattices

Science.gov (United States)

Macrı, T.; Pohl, T.

2014-01-01

We study atoms in optical lattices whose electronic ground state is off-resonantly coupled to a highly excited state with strong binary interactions. We present a time-dependent treatment of the resulting quantum dynamics, which—contrary to recent predictions [36 Li, Ates, and Lesanovsky, Phys. Rev. Lett. 110, 213005 (2013), 10.1103/PhysRevLett.110.213005]—proves that the strong repulsion between the weakly admixed Rydberg states does not lead to atomic trap loss. This finding provides an important basis for creating and manipulating coherent long-range interactions in optical lattice experiments.

Rydberg-state reionization of multiply charged ions escaping from solid surfaces

International Nuclear Information System (INIS)

Nedeljkovic, Lj.D.; Nedeljkovic, N.N.

2003-01-01

Reionization rates of Rydberg states (n>>1 and l=0, 1, and 2) of multiply charged ionic projectiles escaping solid surfaces are calculated. These rates are obtained in an analytic form as a function of the ion-surface distance R. A phenomenological model of the reionization process, based on two-state quantum dynamics, is adopted for the vicinity of the potential barrier top. The results of calculations show that ionization rates for different Rydberg states are strictly localized and relatively separated. Universality of the reionization rate as a function of the scaling parameter α, describing the turning point configurations, is demonstrated. The reionization is discussed within the framework of a nonresonant population-reionization process at intermediate ionic velocities (v∼1 a.u.). The influence of reionization on the population of ionic Rydberg states is expressed in terms of a renormalized neutralization rate. It is demonstrated that the reionization effect significantly changes the population curves for all Rydberg states. The population curves obtained correlate with beam-foil experimental data concerning the S VI, Cl VII, and Ar VIII ions

A paper based inkjet printed real time location tracking TAG

KAUST Repository

Farooqui, Muhammad Fahad

2013-06-01

This paper presents, for the first time, an inkjet printed, wearable, low-cost, light weight and miniaturized real time locating TAG on an ordinary photo-paper. The 29 grams, 9 cm×8 cm×0.5 cm TAG integrates a GPS/GSM module, a microcontroller with on-paper GPS and GSM antennas. A novel monopole antenna with an L shaped slit is introduced to achieve the required circular polarization for the GPS band. Issues related to integration of active components (e.g. BGA chip) on inkjet-printed paper substrates are discussed. The system enables location tracking through a user-friendly interface accessible through all internet enabled devices. Field tests show an update interval of 15 sec, stationary position error of 6.2m and real time tracking error of 4.7m which is 4 times better than the state-of-the-art. Due to the flexible nature of the paper substrate, the TAG can be designed for different shapes such as a wrist band for child tracking or a collar band for pet tracking applications. © 2013 IEEE.

Nonadiabatic holonomic quantum computation using Rydberg blockade

Science.gov (United States)

Kang, Yi-Hao; Chen, Ye-Hong; Shi, Zhi-Cheng; Huang, Bi-Hua; Song, Jie; Xia, Yan

2018-04-01

In this paper, we propose a scheme for realizing nonadiabatic holonomic computation assisted by two atoms and the shortcuts to adiabaticity (STA). The blockade effect induced by strong Rydberg-mediated interaction between two Rydberg atoms provides us the possibility to simplify the dynamics of the system, and the STA helps us design pulses for implementing the holonomic computation with high fidelity. Numerical simulations show the scheme is noise immune and decoherence resistant. Therefore, the current scheme may provide some useful perspectives for realizing nonadiabatic holonomic computation.

Optimal control of Rydberg lattice gases

Science.gov (United States)

Cui, Jian; van Bijnen, Rick; Pohl, Thomas; Montangero, Simone; Calarco, Tommaso

2017-09-01

We present optimal control protocols to prepare different many-body quantum states of Rydberg atoms in optical lattices. Specifically, we show how to prepare highly ordered many-body ground states, GHZ states as well as some superposition of symmetric excitation number Fock states, that inherit the translational symmetry from the Hamiltonian, within sufficiently short excitation times minimising detrimental decoherence effects. For the GHZ states, we propose a two-step detection protocol to experimentally verify the optimised preparation of the target state based only on standard measurement techniques. Realistic experimental constraints and imperfections are taken into account by our optimisation procedure making it applicable to ongoing experiments.

Optimal control of Rydberg lattice gases

DEFF Research Database (Denmark)

Cui, Jian; Bijnen, Rick van; Pohl, Thomas

2017-01-01

the translational symmetry from the Hamiltonian, within sufficiently short excitation times minimising detrimental decoherence effects. For the GHZ states, we propose a two-step detection protocol to experimentally verify the optimised preparation of the target state based only on standard measurement techniques....... Realistic experimental constraints and imperfections are taken into account by our optimisation procedure making it applicable to ongoing experiments.......We present optimal control protocols to prepare different many-body quantum states of Rydberg atoms in optical lattices. Specifically, we show how to prepare highly ordered many-body ground states, GHZ states as well as some superposition of symmetric excitation number Fock states, that inherit...

Evidence of circular Rydberg states in beam-foil experiments: Role of the surface wake field

Science.gov (United States)

Sharma, Gaurav; Puri, Nitin K.; Kumar, Pravin; Nandi, T.

2017-12-01

We have employed the concept of the surface wake field to model the formation of the circular Rydberg states in the beam-foil experiments. The experimental studies of atomic excitation processes show the formation of circular Rydberg states either in the bulk of the foil or at the exit surface, and the mechanism is explained by several controversial theories. The present model is based on the interesting fact that the charge state fraction as well as the surface wake field depend on the foil thickness and it resolves a long-standing discrepancy on the mechanism of the formation of circular Rydberg states. The influence of exit layers is twofold. Initially, the high angular momentum Rydberg states are produced in the last layers of the foil by the Stark switching due to the bulk wake field and finally, they are transferred to the circular Rydberg states as a single multiphoton process due to the influence of the surface wake field.

Autoionizing process of double rydberg states in atom

International Nuclear Information System (INIS)

Xu, X. Y.; Huang, W.; Xu, C. B.; Xue, P.; Chen, D. Y.

1997-01-01

We have studied the autoionization distribution of penetrating double Rydberg (DR) states NLnl(N< n;L,l<4) experimentally in calcium by using five-laser resonance excitation and sequential ionization with a pulsed and a strong constant electric field, as well as theoretically in helium by using the hyperspherical close-coupling method. We have found the DR states autoionize with the ejected electron having its average kinetic energy nearly independent of n but apparently related to the binding energy of the ionic Rydberg orbit NL. We have also discussed the dynamics in DR states and described two types of autoionizing processes, i.e., 'penetration autoionization' and 'polarization autoionization' in DR states

Charge-state-distributions of foil-excited heavy Rydberg atoms

International Nuclear Information System (INIS)

Faibis, A.; Kanter, E.P.; Koenig, W.; Zabransky, B.J.

1985-01-01

Studies of foil-excited fast (MeV/amu) heavy ions have demonstrated large yields of high Rydberg atoms formed in such beams. Further experiments have suggested a strong target-thickness dependence of the yields of such atoms. These results have been puzzling in view of the supposed short mean free paths of such atoms in solids. In an effort to better understand these results, the authors have measured the yields of Rydberg atoms (napprox.100-200) in foil-excited 32 S ions at an incident energy of 125 MeV

Role of ion-pair states in the predissociation dynamics of Rydberg states of molecular iodine.

Science.gov (United States)

von Vangerow, J; Bogomolov, A S; Dozmorov, N V; Schomas, D; Stienkemeier, F; Baklanov, A V; Mudrich, M

2016-07-28

Using femtosecond pump-probe ion imaging spectroscopy, we establish the key role of I(+) + I(-) ion-pair (IP) states in the predissociation dynamics of molecular iodine I2 excited to Rydberg states. Two-photon excitation of Rydberg states lying above the lowest IP state dissociation threshold (1st tier) is found to be followed by direct parallel transitions into IP states of the 1st tier asymptotically correlating to a pair of I ions in their lowest states I(+)((3)P2) + I(-)((1)S0), of the 2nd tier correlating to I(+)((3)P0) + I(-)((1)S0), and of the 3rd tier correlating to I(+)((1)D2) + I(-)((1)S0). Predissociation via the 1st tier proceeds presumably with a delay of 1.6-1.7 ps which is close to the vibrational period in the 3rd tier state (3rd tier-mediated process). The 2nd tier IP state is concluded to be the main precursor for predissociation via lower lying Rydberg states proceeding with a characteristic time of 7-8 ps and giving rise to Rydberg atoms I(5s(2)5p(4)6s(1)). The channel generating I((2)P3/2) + I((2)P1/2) atoms with total kinetic energy corresponding to one-photon excitation is found to proceed via a pump - dump mechanism with dramatic change of angular anisotropy of this channel as compared with earlier nanosecond experiments.

Formation of Rydberg states in fast ion-atom collisions

International Nuclear Information System (INIS)

Schneider, D.; Kanter, E.P.; Vager, Z.; Gemmell, D.; Koch, P.; Mariani, D.; Van de Water, W.

1983-01-01

Previous results from beam-foil spectroscopy and from experiments using field ionization techniques have shown that a significant fraction of fast ionic projectiles traversing solid targets can be excited to high Rydberg states. We report an experimental investigation of Rydberg states formed in atomic and molecular ion beams (MeV) emerging from thin-carbon foils. Different field arrangements, including μ-wave fields, have been applied to study the effects of field ionization. The yields of electrons produced via field ionization are compared for different projectile atoms and molecules

Rydberg states of chloroform studied by VUV photoabsorption spectroscopy

Science.gov (United States)

Singh, Param Jeet; Shastri, Aparna; D'Souza, R.; Jagatap, B. N.

2013-11-01

The VUV photoabsorption spectra of CHCl3 and CDCl3 in the energy region 6.2-11.8 eV (50,000-95,000 cm-1) have been investigated using synchrotron radiation from the Indus-1 source. Rydberg series converging to the first four ionization limits at 11.48, 11.91, 12.01 and 12.85 eV corresponding to excitation from the 1a2, 4a1, 4e, 3e, orbitals of CHCl3 respectively are identified and analyzed. Quantum defect values are observed to be consistent with excitation from the chlorine lone pair orbitals. Vibrational progressions observed in the region of 72,500-76,500 cm-1 have been reassigned to ν3 and combination modes of ν3+ν6 belonging to the 1a2→4p transition in contrast to earlier studies where they were assigned to a ν3 progression superimposed on the 3e→4p Rydberg transition. The assignments are further confirmed based on isotopic substitution studies on CDCl3 whose VUV photoabsorption spectrum is reported here for the first time. The frequencies of the ν3 and ν6 modes in the 4p Rydberg state of CHCl3 (CDCl3) are proposed to be ~454 (409) cm-1 and~130 (129) cm-1 respectively based on the vibronic analysis. DFT calculations of neutral and ionic ground state vibrational frequencies support the vibronic analysis. Experimental spectrum is found to be in good agreement with that predicted by TDDFT calculations. This work presents a consolidated analysis of the VUV photoabsorption spectrum of chloroform.

Investigation by high resolution electron spectroscopy of the helium-like 3lnl' Rydberg series in double capture processes at low collision velocity: auto transfer to Rydberg states and electron stabilization

Energy Technology Data Exchange (ETDEWEB)

Bordenave-Montesquieu, A.; Moretto-Capelle, P.; Gonzalez, A.; Benhenni, M. (Toulouse-3 Univ., 31 (France)); Bachau, H.; Sanchez, I. (Bordeaux-1 Univ., 33 - Talence (France). Lab. des Collisions Atomiques)

1994-09-28

A high resolution electron spectrometry of the (3lnl') Ryberg series populated in N[sup 7+] + He and Ne[sup 10+] + He collisions at 10 q keV, 10[sup o] allows us to observe, for the first time by this method, two post-collisional effects. First, it is found with nitrogen ions that, when n increases from n = 4 to 9, the L-distribution peaks more and more on the high angular momentum states. This is qualitatively understood as a Stark deformation of the Rydberg orbit by the Coulomb field of the receding ion. Also, in the n range where the double capture process populates symmetrical 4l4l' states (n>9), an enhancement of the intensities of the 3lnl' Rydberg lines is observed for both collisonal systems. This is thought to be a signature of the so-called auto transfer to Rydberg states effect. The transfer of population from the 3l4l' to the 3lnl' states is found to be favoured against a direct autoionization of these 4l4l' states into the n = 2 continuum. These experimental findings together with preliminary spectroscopic calculations concerning the configuration interaction of the Ne[sup 8+] (4l4l') states with the Ne[sup 8+](3lnl') Rydberg series are also discussed within the context of the electron stabilization which follows a double capture. (Author).

Fingerprinting of egg and oil binders in painted artworks by matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis of lipid oxidation by-products.

Science.gov (United States)

Calvano, C D; van der Werf, I D; Palmisano, F; Sabbatini, L

2011-06-01

A matrix-assisted laser desorption ionization time-of-flight mass spectrometry-based approach was applied for the detection of various lipid classes, such as triacylglycerols (TAGs) and phospholipids (PLs), and their oxidation by-products in extracts of small (50-100 μg) samples obtained from painted artworks. Ageing of test specimens under various conditions, including the presence of different pigments, was preliminarily investigated. During ageing, the TAGs and PLs content decreased, whereas the amount of diglycerides, short-chain oxidative products arising from TAGs and PLs, and oxidized TAGs and PLs components increased. The examination of a series of model paint samples gave a clear indication that specific ions produced by oxidative cleavage of PLs and/or TAGs may be used as markers for egg and drying oil-based binders. Their elemental composition and hypothetical structure are also tentatively proposed. Moreover, the simultaneous presence of egg and oil binders can be easily and unambiguously ascertained through the simultaneous occurrence of the relevant specific markers. The potential of the proposed approach was demonstrated for the first time by the analysis of real samples from a polyptych of Bartolomeo Vivarini (fifteenth century) and a "French school" canvas painting (seventeenth century).

Molecular Rydberg transitions in carbon monoxide

International Nuclear Information System (INIS)

Fock, J.H.; Guertler, P.; Koch, E.E.

1979-10-01

The linear correlation between the term value and ionization energy for molecular Rydberg transitions is tested for the sequence of isoelectronic molecules BF, CO and N 2 based on a new measurement of the absorption spectrum of CO and data for BF and N 2 . For the npsigma series and npπ series converging on the first ionization potential, we find an excellent linear behavior (within 10 meV) corroborating (I) the correlation and (II) the individual assignments. For Rydberg series leading to the A 2 DELTA and B 2 EPSILON + states, where no data for BF are available, a comparison of term values for CO and N 2 is presented. (orig.)

Photoionization of Rydberg hydrogen atom in a magnetic field

International Nuclear Information System (INIS)

Wang, Dehua; Cheng, Shaohao; Chen, Zhaohang

2015-01-01

Highlights: • The ionization of Rydberg hydrogen atom in a magnetic field has been studied. • Oscillatory structures appear in the electron probability density distributions. • This study can guide the experimental research on the photoionization microscopy. - Abstract: The ionization of Rydberg hydrogen atom in a magnetic field has been studied on the basis of a semiclassical analysis of photoionization microscopy. The photoionization microscopy interference patterns of the photoelectron probability density distribution on a given detector plane are calculated at different scaled energies. We find that due to the interference effect of different types of electron trajectories arrived at a given point on the detector plane, oscillatory structures appear in the electron probability density distributions. The oscillatory structure of the interference pattern, which contains the spatial component of the electronic wave function, evolves sensitively on the scaled energy, through which we gain a deep understanding on the probability density distribution of the electron wave function. This study provides some reference values for the future experiment research on the photoionization microscopy of the Rydberg atom in the presence of magnetic field

Proposal for the determination of nuclear masses by high-precision spectroscopy of Rydberg states

International Nuclear Information System (INIS)

Wundt, B J; Jentschura, U D

2010-01-01

The theoretical treatment of Rydberg states in one-electron ions is facilitated by the virtual absence of the nuclear-size correction, and fundamental constants like the Rydberg constant may be in the reach of planned high-precision spectroscopic experiments. The dominant nuclear effect that shifts transition energies among Rydberg states therefore is due to the nuclear mass. As a consequence, spectroscopic measurements of Rydberg transitions can be used in order to precisely deduce nuclear masses. A possible application of this approach to hydrogen and deuterium, and hydrogen-like lithium and carbon is explored in detail. In order to complete the analysis, numerical and analytic calculations of the quantum electrodynamic self-energy remainder function for states with principal quantum number n = 5, ..., 8 and with angular momentum l = n - 1 and l = n - 2 are described (j = l +- 1/2).

Proposal for the determination of nuclear masses by high-precision spectroscopy of Rydberg states

Energy Technology Data Exchange (ETDEWEB)

Wundt, B J; Jentschura, U D [Department of Physics, Missouri University of Science and Technology, Rolla, MO 65409-0640 (United States)

2010-06-14

The theoretical treatment of Rydberg states in one-electron ions is facilitated by the virtual absence of the nuclear-size correction, and fundamental constants like the Rydberg constant may be in the reach of planned high-precision spectroscopic experiments. The dominant nuclear effect that shifts transition energies among Rydberg states therefore is due to the nuclear mass. As a consequence, spectroscopic measurements of Rydberg transitions can be used in order to precisely deduce nuclear masses. A possible application of this approach to hydrogen and deuterium, and hydrogen-like lithium and carbon is explored in detail. In order to complete the analysis, numerical and analytic calculations of the quantum electrodynamic self-energy remainder function for states with principal quantum number n = 5, ..., 8 and with angular momentum l = n - 1 and l = n - 2 are described (j = l {+-} 1/2).

Cooperative Excitation and Many-Body Interactions in a Cold Rydberg Gas

DEFF Research Database (Denmark)

Viteau, Matthieu; Huillery, Paul; Bason, Mark George

2012-01-01

of the dipole blockade is the suppression of fluctuations in the counting statistics of Rydberg excitations, of which some evidence has been found in previous experiments. Here we present experimental results on the dynamics and the counting statistics of Rydberg excitations of ultracold rubidium atoms both...... on and off resonance, which exhibit sub- and super-Poissonian counting statistics, respectively. We compare our results with numerical simulations using a novel theoretical model based on Dicke states of Rydberg atoms including dipole-dipole interactions, finding good agreement between experiment and theory.......The dipole blockade of Rydberg excitations is a hallmark of the strong interactions between atoms in these high-lying quantum states [ M. Saffman, T. G. Walker and K. Mølmer Rev. Mod. Phys. 82 2313 (2010); D. Comparat and P. Pillet J. Opt. Soc. Am. B 27 A208 (2010)]. One of the consequences...

Implementation of quantum logic gates via Stark-tuned Förster resonance in Rydberg atoms

Science.gov (United States)

Huang, Xi-Rong; Hu, Chang-Sheng; Shen, Li-Tuo; Yang, Zhen-Biao; Wu, Huai-Zhi

2018-02-01

We present a scheme for implementation of controlled-Z and controlled-NOT gates via rapid adiabatic passage and Stark-tuned Förster resonance. By sweeping the Förster resonance once without passing through it and adiabatically tuning the angle-dependent Rydberg-Rydberg interaction of the dipolar nature, the system can be effectively described by a two-level system with the adiabatic theorem. The single adiabatic passage leads to a gate fidelity as high as 0.999 and a greatly reduced gate operation time. We investigate the scheme by considering an actual atomic level configuration with rubidium atoms, where the fidelity of the controlled-Z gate is still higher than 0.99 under the influence of the Zeeman effect.

Comparative Performance of Acoustic-tagged and PIT-tagged Juvenile Salmonids

Energy Technology Data Exchange (ETDEWEB)

Hockersmith, Eric E.; Brown, Richard S.; Liedtke, Theresa L.

2008-02-01

Numerous research tools and technologies are currently being used to evaluate fish passage and survival to determine the impacts of the Federal Columbia River Power System (FCRPS) on endangered and threatened juvenile salmonids, including PIT tags, balloon tags, hydroacoustic evaluations, radio telemetry, and acoustic telemetry. Each has advantages and disadvantages, but options are restricted in some situations because of limited capabilities of a specific technology, lack of detection capability downstream, or availability of adequate numbers of fish. However, there remains concern about the comparative effects of the tag or the tagging procedure on fish performance. The recently developed Juvenile Salmonid Acoustic Telemetry System (JSATS) acoustic transmitter is the smallest active acoustic tag currently available. The goal of this study was to determine whether fish tagged with the JSATS acoustic-telemetry tag can provide unbiased estimates of passage behavior and survival within the performance life of the tag. We conducted both field and laboratory studies to assess tag effects. For the field evaluation we released a total of 996 acoustic-tagged fish in conjunction with 21,026 PIT-tagged fish into the tailrace of Lower Granite Dam on 6 and 13 May. Travel times between release and downstream dams were not significantly different for the majority of the reaches between acoustic-tagged and PIT-tagged fish. In addition to the field evaluation, a series of laboratory experiments were conducted to determine if growth and survival of juvenile Chinook salmon surgically implanted with acoustic transmitters is different than untagged or PIT tagged juvenile Chinook salmon. Only yearling fish with integrated and non-integrated transmitters experienced mortalities, and these were low (<4.5%). Mortality among sub-yearling control and PIT-tag treatments ranged up to 7.7% while integrated and non-integrated treatments had slightly higher rates (up to 8.3% and 7

Analysis of imperfections in the coherent optical excitation of single atoms to Rydberg states

Science.gov (United States)

de Léséleuc, Sylvain; Barredo, Daniel; Lienhard, Vincent; Browaeys, Antoine; Lahaye, Thierry

2018-05-01

We study experimentally various physical limitations and technical imperfections that lead to damping and finite contrast of optically driven Rabi oscillations between ground and Rydberg states of a single atom. Finite contrast is due to preparation and detection errors, and we show how to model and measure them accurately. Part of these errors originates from the finite lifetime of Rydberg states, and we observe its n3 scaling with the principal quantum number n . To explain the damping of Rabi oscillations, we use simple numerical models taking into account independently measured experimental imperfections and show that the observed damping actually results from the accumulation of several small effects, each at the level of a few percent. We discuss prospects for improving the coherence of ground-Rydberg Rabi oscillations in view of applications in quantum simulation and quantum information processing with arrays of single Rydberg atoms.

Asymptotics of Rydberg states for the hydrogen atom

International Nuclear Information System (INIS)

Thomas, L.E.

1997-01-01

The asymptotics of Rydberg states, i.e., highly excited bound states of the hydrogen atom Hamiltonian, and various expectations involving these states are investigated. We show that suitable linear combinations of these states, appropriately rescaled and regarded as functions either in momentum space or configuration space, are highly concentrated on classical momentum space or configuration space Kepler orbits respectively, for large quantum numbers. Expectations of momentum space or configuration space functions with respect to these states are related to time-averages of these functions over Kepler orbits. (orig.)

Correlated Photon Emission from Multiatom Rydberg Dark States

DEFF Research Database (Denmark)

Pritchard, J.D.; Adams, C.S.; Mølmer, Klaus

2012-01-01

We consider three-level atoms driven by two resonant light fields in a ladder scheme where the upper level is a highly excited Rydberg state. We show that the dipole-dipole interactions between Rydberg excited atoms prevents the formation of single particle dark states and leads to strongly corre...... correlated photon pairs from atoms separated by distances large compared to the emission wavelength. For a pair of atoms, this enables realization of an efficient photon-pair source with on average one pair every 30 μs....

Cavity electromagnetically induced transparency with Rydberg atoms

Science.gov (United States)

Bakar Ali, Abu; Ziauddin

2018-02-01

Cavity electromagnetically induced transparency (EIT) is revisited via the input probe field intensity. A strongly interacting Rydberg atomic medium ensemble is considered in a cavity, where atoms behave as superatoms (SAs) under the dipole blockade mechanism. Each atom in the strongly interacting Rydberg atomic medium (87 Rb) follows a three-level cascade atomic configuration. A strong control and weak probe field are employed in the cavity with the ensemble of Rydberg atoms. The features of the reflected and transmitted probe light are studied under the influence of the input probe field intensity. A transparency peak (cavity EIT) is revealed at a resonance condition for small values of input probe field intensity. The manipulation of the cavity EIT is reported by tuning the strength of the input probe field intensity. Further, the phase and group delay of the transmitted and reflected probe light are studied. It is found that group delay and phase in the reflected light are negative, while for the transmitted light they are positive. The magnitude control of group delay in the transmitted and reflected light is investigated via the input probe field intensity.

Observation of the Borromean Three-Body Förster Resonances for Three Interacting Rb Rydberg Atoms.

Science.gov (United States)

Tretyakov, D B; Beterov, I I; Yakshina, E A; Entin, V M; Ryabtsev, I I; Cheinet, P; Pillet, P

2017-10-27

Three-body Förster resonances at long-range interactions of Rydberg atoms were first predicted and observed in Cs Rydberg atoms by Faoro et al. [Nat. Commun. 6, 8173 (2015)NCAOBW2041-172310.1038/ncomms9173]. In these resonances, one of the atoms carries away an energy excess preventing the two-body resonance, leading thus to a Borromean type of Förster energy transfer. But they were in fact observed as the average signal for the large number of atoms N≫1. In this Letter, we report on the first experimental observation of the three-body Förster resonances 3×nP_{3/2}(|M|)→nS_{1/2}+(n+1)S_{1/2}+nP_{3/2}(|M^{*}|) in a few Rb Rydberg atoms with n=36, 37. We have found here clear evidence that there is no signature of the three-body Förster resonance for exactly two interacting Rydberg atoms, while it is present for N=3-5 atoms. This demonstrates the assumption that three-body resonances can generalize to any Rydberg atom. As such resonance represents an effective three-body operator, it can be used to directly control the three-body interactions in quantum simulations and quantum information processing with Rydberg atoms.

Radio-frequency-modulated Rydberg states in a vapor cell

Science.gov (United States)

Miller, S. A.; Anderson, D. A.; Raithel, G.

2016-05-01

We measure strong radio-frequency (RF) electric fields using rubidium Rydberg atoms prepared in a room-temperature vapor cell as field sensors. Electromagnetically induced transparency is employed as an optical readout. We RF-modulate the 60{{{S}}}1/2 and 58{{{D}}}5/2 Rydberg states with 50 and 100 MHz fields, respectively. For weak to moderate RF fields, the Rydberg levels become Stark-shifted, and sidebands appear at even multiples of the driving frequency. In high fields, the adjacent hydrogenic manifold begins to intersect the shifted levels, providing rich spectroscopic structure suitable for precision field measurements. A quantitative description of strong-field level modulation and mixing of S and D states with hydrogenic states is provided by Floquet theory. Additionally, we estimate the shielding of DC electric fields in the interior of the glass vapor cell.

Billfish Tagging

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The SWFSC's constituent-based Billfish Tagging Program began in 1963 and since that time has provided conventional spaghetti type tags and tagging supplies to...

Interaction of K(nd) Rydberg atoms with an amorphous gold surface

International Nuclear Information System (INIS)

Gray, D.F.

1988-01-01

This thesis reports the first controlled study of the interactions of Rydberg atoms with a metal surface. In these experiments, a collimated beam of potassium Rydberg atoms is directed at a plane surface at near grazing incidence. Positive ions formed by surface ionization are attracted to the surface by their image charge, which is counterbalanced by an external electric field applied perpendicular to the surface. The ions are detected by a position-sensitive detector (PSD). At some critical value of the external field, the ion trajectories just miss the surface, suggesting that analysis of the dependence of the ion signals of external electric field can be used to determine the distance from the surface at which ionization occurs. This distance, and thus the corresponding critical electric field, is expected to be n-dependent. Experimentally, however, it was observed that the ion signal had a sudden n-independent onset when only a small positive perpendicular electric field was applied at the surface. This observation requires, surprisingly, that the ions produced by surface ionization can readily escape from the surface. The data do, however, show that Rydberg atoms are efficiently ionized in collisions with the surface. This process may provide a useful new detection technique for Rydberg atoms

Fundamental constants and tests of theory in Rydberg states of hydrogenlike ions.

Science.gov (United States)

Jentschura, Ulrich D; Mohr, Peter J; Tan, Joseph N; Wundt, Benedikt J

2008-04-25

A comparison of precision frequency measurements to quantum electrodynamics (QED) predictions for Rydberg states of hydrogenlike ions can yield information on values of fundamental constants and test theory. With the results of a calculation of a key QED contribution reported here, the uncertainty in the theory of the energy levels is reduced to a level where such a comparison can yield an improved value of the Rydberg constant.

Fundamental Constants and Tests of Theory in Rydberg States of Hydrogenlike Ions

International Nuclear Information System (INIS)

Jentschura, Ulrich D.; Mohr, Peter J.; Tan, Joseph N.; Wundt, Benedikt J.

2008-01-01

A comparison of precision frequency measurements to quantum electrodynamics (QED) predictions for Rydberg states of hydrogenlike ions can yield information on values of fundamental constants and test theory. With the results of a calculation of a key QED contribution reported here, the uncertainty in the theory of the energy levels is reduced to a level where such a comparison can yield an improved value of the Rydberg constant

Real-time flavor tagging selection in ATLAS

CERN Document Server

Madaffari, D

2016-01-01

In high-energy physics experiments the online selection is crucial to reject the overwhelming uninteresting collisions. In particular the ATLAS experiment includes b-jet selections in its trigger, in order to select final states with significant heavy-flavor content. Dedicated selections are developed to timely identifying fully hadronic final states containing b-jets and maintaining affordable trigger rates. ATLAS successfully operated b-jet trigger selections during both 2011 and 2012 Large Hadron Collider data-taking campaigns. Work is on-going now to improve the performance of online tagging algorithms to be deployed in Run 2 in 2015. An overview of the Run 1 ATLAS b-jet trigger strategy along with future prospects is presented in this paper. Data-driven techniques to extract the online b-tagging performance, a key ingredient for all analysis relying on such triggers, are also discussed and preliminary results presented.

Quantum simulation of transverse Ising models with Rydberg atoms

Science.gov (United States)

Schauss, Peter

2018-04-01

Quantum Ising models are canonical models for the study of quantum phase transitions (Sachdev 1999 Quantum Phase Transitions (Cambridge: Cambridge University Press)) and are the underlying concept for many analogue quantum computing and quantum annealing ideas (Tanaka et al Quantum Spin Glasses, Annealing and Computation (Cambridge: Cambridge University Press)). Here we focus on the implementation of finite-range interacting Ising spin models, which are barely tractable numerically. Recent experiments with cold atoms have reached the interaction-dominated regime in quantum Ising magnets via optical coupling of trapped neutral atoms to Rydberg states. This approach allows for the tunability of all relevant terms in an Ising spin Hamiltonian with 1/{r}6 interactions in transverse and longitudinal fields. This review summarizes the recent progress of these implementations in Rydberg lattices with site-resolved detection. Strong correlations in quantum Ising models have been observed in several experiments, starting from a single excitation in the superatom regime up to the point of crystallization. The rapid progress in this field makes spin systems based on Rydberg atoms a promising platform for quantum simulation because of the unmatched flexibility and strength of interactions combined with high control and good isolation from the environment.

High-fidelity Rydberg quantum gate via a two-atom dark state

DEFF Research Database (Denmark)

Petrosyan, David; Motzoi, Felix; Saffman, Mark

2017-01-01

We propose a two-qubit gate for neutral atoms in which one of the logical state components adiabatically follows a two-atom dark state formed by the laser coupling to a Rydberg state and a strong, resonant dipole-dipole exchange interaction between two Rydberg excited atoms. Our gate exhibits...

Many-body dynamics of driven-dissipative Rydberg cavity polaritons

Science.gov (United States)

Pistorius, Tim; Fan, Jingtao; Weimer, Hendrik

2017-04-01

The usage of photons as long-range information carriers has greatly increased the interest in systems with nonlinear optical properties in recent years. The nonlinearity is easily achievable in Rydberg mediums through the strong van der Waals interaction which makes them one of the best candidates for such a system. Here, we propose a way to analyze the steady state solutions of a Rydberg medium in a cavity through the combination of the variational principle for open quantum systems and the P-distribution of the density matrix. To get a better understanding of the many-body-dynamics a transformation into the polariton picture is performed and investigated. Volkswagen Foundation, Deutsche Forschungsgemeinschaft.

Response probability and response time: a straight line, the Tagging/Retagging interpretation of short term memory, an operational definition of meaningfulness and short term memory time decay and search time.

Science.gov (United States)

Tarnow, Eugen

2008-12-01

The functional relationship between correct response probability and response time is investigated in data sets from Rubin, Hinton and Wenzel, J Exp Psychol Learn Mem Cogn 25:1161-1176, 1999 and Anderson, J Exp Psychol [Hum Learn] 7:326-343, 1981. The two measures are linearly related through stimulus presentation lags from 0 to 594 s in the former experiment and for repeated learning of words in the latter. The Tagging/Retagging interpretation of short term memory is introduced to explain this linear relationship. At stimulus presentation the words are tagged. This tagging level drops slowly with time. When a probe word is reintroduced the tagging level has to increase for the word to be properly identified leading to a delay in response time. The tagging time is related to the meaningfulness of the words used-the more meaningful the word the longer the tagging time. After stimulus presentation the tagging level drops in a logarithmic fashion to 50% after 10 s and to 20% after 240 s. The incorrect recall and recognition times saturate in the Rubin et al. data set (they are not linear for large time lags), suggesting a limited time to search the short term memory structure: the search time for recall of unusual words is 1.7 s. For recognition of nonsense words the corresponding time is about 0.4 s, similar to the 0.243 s found in Cavanagh (1972).

Electromagnetically induced grating with Rydberg atoms

Science.gov (United States)

Asghar, Sobia; Ziauddin, Qamar, Shahid; Qamar, Sajid

2016-09-01

We present a scheme to realize electromagnetically induced grating in an ensemble of strongly interacting Rydberg atoms, which act as superatoms due to the dipole blockade mechanism. The ensemble of three-level cold Rydberg-dressed (87Rb) atoms follows a cascade configuration where a strong standing-wave control field and a weak probe pulse are employed. The diffraction intensity is influenced by the strength of the probe intensity, the control field strength, and the van der Waals (vdW) interaction. It is noticed that relatively large first-order diffraction can be obtained for low-input intensity with a small vdW shift and a strong control field. The scheme can be considered as an amicable solution to realize the atomic grating at the microscopic level, which can provide background- and dark-current-free diffraction.

Time-of-flight spectrometers

International Nuclear Information System (INIS)

Carrico, J.P.

1976-01-01

The flight time of an ion in an inhomogeneous, oscillatory electric field (IOFE) is an m/e-dependent property of this field and is independent of the initial position and velocity. The d.c. component of the equation of motion for an ion in the IOFE describes a harmonic oscillation of constant period. When ions oscillate for many periods with one species overtaking another the motion may no longer be truly periodic although the resulting period or 'quasi-period' still remains independent of the initial conditions. This period or 'quasi-period' is used in the time-of-flight mass spectrometer described. The principle of operation is also described and both analytical and experimental results are reported. (B.D.)

Principles of time-of-flight tomography

International Nuclear Information System (INIS)

Campagnolo, R.; Garderet, P.; Lecomte, J.L.; Bouvier, A.; Darier, P.; Soussaline, F.

1983-03-01

After a short introduction to the physics of time-of-flight positron tomography, the various aspects of this technique are presented. The characteristics including data acquisition and image reconstruction system of a positron tomograph (TTV01) which uses time-of-flight information, are described. The preliminary results obtained with TTV01, such as resolution and sensitivity, as well as phantom images, are presented [fr

Effect of finite detection efficiency on the observation of the dipole-dipole interaction of a few Rydberg atoms

International Nuclear Information System (INIS)

Ryabtsev, I. I.; Tretyakov, D. B.; Beterov, I. I.; Entin, V. M.

2007-01-01

We have developed a simple analytical model describing multiatom signals that are measured in experiments on dipole-dipole interaction at resonant collisions of a few Rydberg atoms. It has been shown that finite efficiency of the selective field-ionization detector leads to the mixing up of the spectra of resonant collisions registered for various numbers of Rydberg atoms. The formulas which help to estimate an appropriate mean Rydberg atom number for a given detection efficiency are presented. We have found that a measurement of the relation between the amplitudes of collisional resonances observed in the one- and two-atom signals provides a straightforward determination of the absolute detection efficiency and mean Rydberg atom number. We also performed a testing experiment on resonant collisions in a small excitation volume of a sodium atomic beam. The resonances observed for 1-4 detected Rydberg atoms have been analyzed and compared with theory

Entropy and complexity analysis of hydrogenic Rydberg atoms

Energy Technology Data Exchange (ETDEWEB)

Lopez-Rosa, S. [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain); Departamento de Fisica Aplicada II, Universidad de Sevilla, 41012-Sevilla (Spain); Toranzo, I. V.; Dehesa, J. S. [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain); Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, 18071-Granada (Spain); Sanchez-Moreno, P. [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain); Departamento de Matematica Aplicada, Universidad de Granada, 18071-Granada (Spain)

2013-05-15

The internal disorder of hydrogenic Rydberg atoms as contained in their position and momentum probability densities is examined by means of the following information-theoretic spreading quantities: the radial and logarithmic expectation values, the Shannon entropy, and the Fisher information. As well, the complexity measures of Cramer-Rao, Fisher-Shannon, and Lopez Ruiz-Mancini-Calvet types are investigated in both reciprocal spaces. The leading term of these quantities is rigorously calculated by use of the asymptotic properties of the concomitant entropic functionals of the Laguerre and Gegenbauer orthogonal polynomials which control the wavefunctions of the Rydberg states in both position and momentum spaces. The associated generalized Heisenberg-like, logarithmic and entropic uncertainty relations are also given. Finally, application to linear (l= 0), circular (l=n- 1), and quasicircular (l=n- 2) states is explicitly done.

Trojan wavepackets in helium - by core-Rydberg interaction

International Nuclear Information System (INIS)

Kalinski, M.; Eberly, J.H.

1996-01-01

The authors exhibit the existence of core-induced shape invariant wave packets in helium analogous to the Trojan wave packets predicted for hydrogen. They show that the core dipole moment oscillating with the Rabi frequency in the presence of a laser field will cause both radical and angular confinement of an outer Rydberg electron moving around a nearly circular orbit if the parameters of the orbit are properly chosen. They find the relation between the Rabi frequency of the core electron oscillations, laser field strength and the parameters of the Rydberg orbit of the outer electron

Evolution from Rydberg gas to ultracold plasma in a supersonic atomic beam of Xe

International Nuclear Information System (INIS)

Hung, J; Sadeghi, H; Schulz-Weiling, M; Grant, E R

2014-01-01

A Rydberg gas of xenon, entrained in a supersonic atomic beam, evolves slowly to form an ultracold plasma. In the early stages of this evolution, when the free-electron density is low, Rydberg atoms undergo long-range ℓ-mixing collisions, yielding states of high orbital angular momentum. The development of high-ℓ states promotes dipole–dipole interactions that help to drive Penning ionization. The electron density increases until it reaches the threshold for avalanche. Ninety μs after the production of a Rydberg gas with the initial state, n 0 ℓ 0 =42d, a 432 V cm −1 electrostatic pulse fails to separate charge in the excited volume, an effect which is ascribed to screening by free electrons. Photoexcitation cross sections, observed rates of ℓ-mixing, and a coupled-rate-equation model simulating the onset of the electron-impact avalanche point consistently to an initial Rydberg gas density of 5×10 8 cm −3 . (paper)

Newton's Cradle and Entanglement Transport in a Flexible Rydberg Chain

International Nuclear Information System (INIS)

Wuester, S.; Ates, C.; Eisfeld, A.; Rost, J. M.

2010-01-01

In a regular, flexible chain of Rydberg atoms, a single electronic excitation localizes on two atoms that are in closer mutual proximity than all others. We show how the interplay between excitonic and atomic motion causes electronic excitation and diatomic proximity to propagate through the Rydberg chain as a combined pulse. In this manner entanglement is transferred adiabatically along the chain, reminiscent of momentum transfer in Newton's cradle.

Formation of Antihydrogen Rydberg atoms in strong magnetic field traps

International Nuclear Information System (INIS)

Pohl, T.; Sadeghpour, H. R.

2008-01-01

It is shown that several features of antihydrogen production in nested Penning traps can be described with accurate and efficient Monte Carlo simulations. It is found that cold deeply-bound Rydberg states of antihydrogen (H-bar) are produced in three-body capture in the ATRAP experiments and an additional formation mechanism -Rydberg charge transfer-, particular to the nested Penning trap geometry, is responsible for the observed fast (hot) H-bar atoms. Detailed description of the numerical propagation technique for following extreme close encounters is given. An analytic derivation of the power law behavior of the field ionization spectrum is provided

Heavy Rydberg behaviour in high vibrational levels of some ion-pair states of the halogens and inter-halogens

International Nuclear Information System (INIS)

Donovan, Robert J.; Lawley, Kenneth P.; Ridley, Trevor

2015-01-01

We report the identification of heavy Rydberg resonances in the ion-pair spectra of I 2 , Cl 2 , ICl, and IBr. Extensive vibrational progressions are analysed in terms of the energy dependence of the quantum defect δ(E b ) rather than as Dunham expansions. This is shown to define the heavy Rydberg region, providing a more revealing fit to the data with fewer coefficients and leads just as easily to numbering data sets separated by gaps in the observed vibrational progressions. Interaction of heavy Rydberg states with electronic Rydberg states at avoided crossings on the inner wall of the ion-pair potential is shown to produce distinctive changes in the energy dependence of δ(E b ), with weak and strong interactions readily distinguished. Heavy Rydberg behaviour is found to extend well below near-dissociation states, down to vibrational levels ∼18 000-20 000 cm −1 below dissociation. The rapid semi-classical calculation of δ(E b ) for heavy Rydberg states is emphasised and shows their absolute magnitude to be essentially the volume of phase space excluded from the vibrational motion by avoiding core-core penetration of the ions

Time-resolved Fourier-transform infrared emission spectroscopy of Au in the 1800-4000-cm(-1) region: Rydberg transitions

Czech Academy of Sciences Publication Activity Database

Civiš, Svatopluk; Matulková, Irena; Cihelka, Jaroslav

2010-01-01

Roč. 81, č. 1 (2010), 012510 ISSN 1050-2947 R&D Projects: GA AV ČR IAA400400705; GA AV ČR KAN100500652 Institutional research plan: CEZ:AV0Z40400503 Keywords : spectroscopy * Rydberg transitions * theoretical chemistry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.861, year: 2010

Determination of first ionization potential of samarium atom using Rydberg series convergence

International Nuclear Information System (INIS)

Jayasekharan, T.; Razvi, M.A.N.; Bhale, G.L.

1999-01-01

The study of Rydberg states has recently received more attention partially because an efficient isotope selective ionization is possible via these states. In addition, their investigation provides useful information on the atomic structure. An electron in a shell with a high principal quantum number is a sensitive probe for the interaction with the ionic core of the atom. Measurements of these Rydberg levels give valuable data on quantum defects, anomalies in fine structure splitting, polarizabilities, configuration interactions, ionization potentials etc

Multibit C_kNOT quantum gates via Rydberg blockade

DEFF Research Database (Denmark)

Isenhower, L.; Saffman, Mark; Mølmer, Klaus

2011-01-01

Long range Rydberg blockade interactions have the potential for efficient implementation of quantum gates between multiple atoms. Here we present and analyze a protocol for implementation of a k-atom controlled NOT (CkNOT) neutral atom gate. This gate can be implemented using sequential or simult......Long range Rydberg blockade interactions have the potential for efficient implementation of quantum gates between multiple atoms. Here we present and analyze a protocol for implementation of a k-atom controlled NOT (CkNOT) neutral atom gate. This gate can be implemented using sequential...... or simultaneous addressing of the control atoms which requires only 2k + 3 or 5 Rydberg π pulses respectively. A detailed error analysis relevant for implementations based on alkali atom Rydberg states is provided which shows that gate errors less than 10% are possible for k = 35....

Entropy and complexity analysis of hydrogenic Rydberg atoms

International Nuclear Information System (INIS)

López-Rosa, S.; Toranzo, I. V.; Dehesa, J. S.; Sánchez-Moreno, P.

2013-01-01

The internal disorder of hydrogenic Rydberg atoms as contained in their position and momentum probability densities is examined by means of the following information-theoretic spreading quantities: the radial and logarithmic expectation values, the Shannon entropy, and the Fisher information. As well, the complexity measures of Crámer-Rao, Fisher-Shannon, and López Ruiz-Mancini-Calvet types are investigated in both reciprocal spaces. The leading term of these quantities is rigorously calculated by use of the asymptotic properties of the concomitant entropic functionals of the Laguerre and Gegenbauer orthogonal polynomials which control the wavefunctions of the Rydberg states in both position and momentum spaces. The associated generalized Heisenberg-like, logarithmic and entropic uncertainty relations are also given. Finally, application to linear (l= 0), circular (l=n− 1), and quasicircular (l=n− 2) states is explicitly done.

REAL-TIME FLAVOUR TAGGING SELECTION IN ATLAS

CERN Document Server

Bokan, Petar; The ATLAS collaboration

2016-01-01

The ATLAS experiment includes a well-developed trigger system that allows a selection of events which are thought to be of interest, while achieving a high overall rejection against less interesting processes. An important part of the online event selection is the ability to distinguish between jets arising from heavy-flavour quarks (b- and c-jets) and light jets (jets from u-, d-, s- and gluon jets) in real-time. This is essential for many physics analysis that include processes with large jet multiplicity and b-quarks in the final state. Many changes were implemented to the ATLAS online b-jet selection for the Run-2 of the LHC. An overview of the b-jet trigger strategy and performance during 2015 data taking is presented. The ability to use complex offline Multivariate (MV2) b-tagging algorithms directly at High Level Trigger (HLT) was tested in this period. Details on online tagging algorithms are given together with the plans on how to adapt to the new high-luminosity and increased pileup conditions by ex...

Spin-interaction effects for ultralong-range Rydberg molecules in a magnetic field

Science.gov (United States)

Hummel, Frederic; Fey, Christian; Schmelcher, Peter

2018-04-01

We investigate the fine and spin structure of ultralong-range Rydberg molecules exposed to a homogeneous magnetic field. Each molecule consists of a 87Rb Rydberg atom the outer electron of which interacts via spin-dependent s - and p -wave scattering with a polarizable 87Rb ground-state atom. Our model includes also the hyperfine structure of the ground-state atom as well as spin-orbit couplings of the Rydberg and ground-state atom. We focus on d -Rydberg states and principal quantum numbers n in the vicinity of 40. The electronic structure and vibrational states are determined in the framework of the Born-Oppenheimer approximation for varying field strengths ranging from a few up to hundred Gauss. The results show that the interplay between the scattering interactions and the spin couplings gives rise to a large variety of molecular states in different spin configurations as well as in different spatial arrangements that can be tuned by the magnetic field. This includes relatively regularly shaped energy surfaces in a regime where the Zeeman splitting is large compared to the scattering interaction but small compared to the Rydberg fine structure, as well as more complex structures for both weaker and stronger fields. We quantify the impact of spin couplings by comparing the extended theory to a spin-independent model.

Extracting Usage Patterns and the Analysis of Tag Connection Dynamics within Collaborative Tagging Systems

Directory of Open Access Journals (Sweden)

Daniel MICAN

2013-01-01

Full Text Available Collaborative tagging has become a very popular way of annotation, thanks to the fact that any entity may be labeled by any individual based on his own reason. In this paper we present the results of the case study carried out on the basis of data gathered at different time intervals from the social tagging system developed and implemented on Întelepciune.ro. Analyzing collective data referring to the way in which community members associate different tags, we have observed that between tags, links are formed which become increasingly stable with the passing of time. Following the application of methodology specific to network analysis, we have managed to extract information referring to tag popularity, their influence within the network and the degree to which a tag depends upon another. As such, we have succeeded in determining different semantic structures within the collective tagging system and see their evolution at different stages in time. Furthermore, we have pictured the way in which tag rec-ommendations can be executed and that they can be integrated within recommendation sys-tems. Thus, we will be able to identify experts and trustworthy content based on different cat-egories of interest.

Rabi Oscillations between Ground and Rydberg States with Dipole-Dipole Atomic Interactions

International Nuclear Information System (INIS)

Johnson, T. A.; Urban, E.; Henage, T.; Isenhower, L.; Yavuz, D. D.; Walker, T. G.; Saffman, M.

2008-01-01

We demonstrate Rabi oscillations of small numbers of 87 Rb atoms between ground and Rydberg states with n≤43. Coherent population oscillations are observed for single atoms, while the presence of two or more atoms decoheres the oscillations. We show that these observations are consistent with van der Waals interactions of Rydberg atoms

Observation and measurement of interaction-induced dispersive optical nonlinearities in an ensemble of cold rydberg atoms

DEFF Research Database (Denmark)

Parigi, V.; Bimbard, E.; Stanojevic, J.

2012-01-01

We observe and measure dispersive optical nonlinearities in an ensemble of cold Rydberg atoms placed inside an optical cavity. The experimental results are in agreement with a simple model where the optical nonlinearities are due to the progressive appearance of a Rydberg blockaded volume within...

Predissociation of high-lying Rydberg states of molecular iodine via ion-pair states

Energy Technology Data Exchange (ETDEWEB)

Bogomolov, Alexandr S. [Institute of Chemical Kinetics and Combustion, Institutskaya Str. 3, Novosibirsk 630090 (Russian Federation); Grüner, Barbara; Mudrich, Marcel [Physikalisches Institut, Universität Freiburg, D-79104 Freiburg (Germany); Kochubei, Sergei A. [Institute of Semiconductor Physics, ac. Lavrent' yev ave., 13, Novosibirsk 630090 (Russian Federation); Baklanov, Alexey V. [Institute of Chemical Kinetics and Combustion, Institutskaya Str. 3, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090 (Russian Federation)

2014-03-28

Velocity map imaging of the photofragments arising from two-photon photoexcitation of molecular iodine in the energy range 73 500–74 500 cm{sup −1} covering the bands of high-lying gerade Rydberg states [{sup 2}Π{sub 1/2}]{sub c}6d;0{sub g}{sup +} and [{sup 2}Π{sub 1/2}]{sub c}6d;2{sub g} has been applied. The ion signal was dominated by the atomic fragment ion I{sup +}. Up to 5 dissociation channels yielding I{sup +} ions with different kinetic energies were observed when the I{sub 2} molecule was excited within discrete peaks of Rydberg states and their satellites in this region. One of these channels gives rise to images of I{sup +} and I{sup −} ions with equal kinetic energy indicating predissociation of I{sub 2} via ion-pair states. The contribution of this channel was up to about 50% of the total I{sup +} signal. The four other channels correspond to predissociation via lower lying Rydberg states giving rise to excited iodine atoms providing I{sup +} ions by subsequent one-photon ionization by the same laser pulse. The ratio of these channels varied from peak to peak in the spectrum but their total ionic signal was always much higher than the signal of (2 + 1) resonance enhanced multi-photon ionization of I{sub 2}, which was previously considered to be the origin of ionic signal in this spectral range. The first-tier E0{sub g}{sup +} and D{sup ′}2{sub g} ion-pair states are concluded to be responsible for predissociation of Rydberg states [{sup 2}Π{sub 1/2}]{sub c}6d;0{sub g}{sup +} and [{sup 2}Π{sub 1/2}]{sub c}6d;2{sub g}, respectively. Further predissociation of these ion-pair states via lower lying Rydberg states gives rise to excited I(5s{sup 2}5p{sup 4}6s{sup 1}) atoms responsible for major part of ion signal. The isotropic angular distribution of the photofragment recoil directions observed for all channels indicates that the studied Rydberg states are long-lived compared with the rotational period of the I{sub 2} molecule.

Single-photon cesium Rydberg excitation spectroscopy using 318.6-nm UV laser and room-temperature vapor cell.

Science.gov (United States)

Wang, Jieying; Bai, Jiandong; He, Jun; Wang, Junmin

2017-09-18

We demonstrate a single-photon Rydberg excitation spectroscopy of cesium (Cs) atoms in a room-temperature vapor cell. Cs atoms are excited directly from 6S 1/2 ground state to nP 3/2 (n = 70 - 100) Rydberg states with a 318.6 nm ultraviolet (UV) laser, and Rydberg excitation spectra are obtained by transmission enhancement of a probe beam resonant to Cs 6S 1/2 , F = 4 - 6P 3/2 , F' = 5 transition as partial population on F = 4 ground state are transferred to Rydberg state. Analysis reveals that the observed spectra are velocity-selective spectroscopy of Rydberg state, from which the amplitude and linewidth influenced by lasers' Rabi frequency have been investigated. Fitting to energies of Cs nP 3/2 (n = 70 -100) states, the determined quantum defect is 3.56671(42). The demodulated spectra can also be employed as frequency references to stabilize the UV laser frequency to specific Cs Rydberg transition.

Rocket-borne time-of-flight mass spectrometry

Science.gov (United States)

Reiter, R. F.

1976-01-01

Theoretical and numerical analyses are made of planar, cylindrical and spherical-electrode two-field time-of-flight mass spectrometers in order to optimize their operating conditions. A method is introduced which can improve the resolving power of these instruments by a factor of 7.5. Potential barrier gating in time-of-flight mass spectrometers is also analyzed. Experimental studies of a miniature cylindrical-electrode and a hemispherical-electrode time-of-flight mass spectrometer are presented. Their sensitivity and ability to operate at D-region pressures with an open source make them ideal instruments for D-region ion composition measurements. A sounding rocket experiment package carrying a cylindrical electrode time-of-flight mass spectrometer was launched. The data indicate that essentially 100% of the positive electric charge on positive ions is carried by ions with mass-to-charge ratios greater than 500 below an altitude of 92 km. These heavy charge carriers were present at altitudes up to about 100 km.

Rocket-borne time-of-flight mass spectrometry

International Nuclear Information System (INIS)

Reiter, R.F.

1976-08-01

Theoretical and numerical analyses are made of planar-, cylindrical- and spherical-electrode two-field time-of-flight mass spectrometers in order to optimize their operating conditions. A method is introduced which can improve the resolving power of these instruments by a factor of 7.5. Potential barrier gating in time-of-flight mass spectrometers is also analyzed. Experimental studies of a miniature cylindrical-electrode and a hemispherical-electrode time-of-flight mass spectrometer are presented. Their sensitivity and ability to operate at D-region pressures with an open source make them ideal instruments for D-region ion composition measurements. A sounding rocket experiment package carrying a cylindrical electrode time-of-flight mass spectrometer was launched. The data indicate that essentially 100% of the positive electric charge on positive ions is carried by ions with mass-to-charge ratios greater than 500 below an altitude of 92 km. These heavy charge carriers were present at altitudes up to about 100 km

Dissipation-induced dipole blockade and antiblockade in driven Rydberg systems

Science.gov (United States)

Young, Jeremy T.; Boulier, Thomas; Magnan, Eric; Goldschmidt, Elizabeth A.; Wilson, Ryan M.; Rolston, Steven L.; Porto, James V.; Gorshkov, Alexey V.

2018-02-01

We study theoretically and experimentally the competing blockade and antiblockade effects induced by spontaneously generated contaminant Rydberg atoms in driven Rydberg systems. These contaminant atoms provide a source of strong dipole-dipole interactions and play a crucial role in the system's behavior. We study this problem theoretically using two different approaches. The first is a cumulant expansion approximation, in which we ignore third-order and higher connected correlations. Using this approach for the case of resonant drive, a many-body blockade radius picture arises, and we find qualitative agreement with previous experimental results. We further predict that as the atomic density is increased, the Rydberg population's dependence on Rabi frequency will transition from quadratic to linear dependence at lower Rabi frequencies. We study this behavior experimentally by observing this crossover at two different atomic densities. We confirm that the larger density system has a smaller crossover Rabi frequency than the smaller density system. The second theoretical approach is a set of phenomenological inhomogeneous rate equations. We compare the results of our rate-equation model to the experimental observations [E. A. Goldschmidt et al., Phys. Rev. Lett. 116, 113001 (2016), 10.1103/PhysRevLett.116.113001] and find that these rate equations provide quantitatively good scaling behavior of the steady-state Rydberg population for both resonant and off-resonant drives.

Data for analysis of mannose-6-phosphate glycans labeled with fluorescent tags.

Science.gov (United States)

Kang, Ji-Yeon; Kwon, Ohsuk; Gil, Jin Young; Oh, Doo-Byoung

2016-06-01

Mannose-6-phosphate (M-6-P) glycan plays an important role in lysosomal targeting of most therapeutic enzymes for treatment of lysosomal storage diseases. This article provides data for the analysis of M-6-P glycans by high-performance liquid chromatography (HPLC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The identities of M-6-P glycan peaks in HPLC profile were confirmed by measuring the masses of the collected peak eluates. The performances of three fluorescent tags (2-aminobenzoic acid [2-AA], 2-aminobenzamide [2-AB], and 3-(acetyl-amino)-6-aminoacridine [AA-Ac]) were compared focusing on the analysis of bi-phosphorylated glycan (containing two M-6-Ps). The bi-phosphorylated glycan analysis is highly affected by the attached fluorescent tag and the hydrophilicity of elution solvent used in HPLC. The data in this article is associated with the research article published in "Comparison of fluorescent tags for analysis of mannose-6-phosphate glycans" (Kang et al., 2016 [1]).

Nuclear spin transitions in the kHz range in Rydberg matter clusters give precise values of the internal magnetic field from orbiting Rydberg electrons

International Nuclear Information System (INIS)

Holmlid, Leif

2009-01-01

Clusters of the electronically excited condensed matter Rydberg matter (RM) are planar and sixfold symmetric with specific magic numbers N as shown by rotational spectroscopy of potassium K N clusters [L. Holmlid, Mol. Phys. 105 (2007) 933; L. Holmlid, J. Mol. Struct. 885 (2008) 122]. In radio frequency emission spectra from such clusters, features are observed that are due to the hyperfine interaction between the atomic nucleus 39 K and two Rydberg electrons. These electrons exist in a doubly excited K atom at n'' = 5 or 6 in a 'sleeping-top' type rotating cluster. Such low excited electrons were observed recently in optical intra-cavity experiments in K(RM), where the electrons in the conduction band are involved in the angular momentum conservation in the stimulated emission. Here we show that the agreement with the theoretical description of circular Rydberg states is excellent within ±0.2% in the magnetic field, invoking angular momentum conservation by electrons in the condensed phase. Sleeping-top clusters may form stacks of clusters, and it is likely that such stacks are the emitting entities involved in the two nuclear spin series observed.

Discharge residence of TLD tagged fish

International Nuclear Information System (INIS)

Romberg, G.P.; Prepejchal, W.

1974-01-01

Although visual observations suggested that fish remained in the discharge for considerable periods, temperature-sensitive tags indicated the majority of fish spend less than 50 hr or 10 percent of the time at discharge temperatures. During 1974 a second fish tagging study was conducted, using temperature-sensitive tags to yield discharge residence times of Lake Michigan salmonids at Point Beach thermal discharge. Preliminary results revealed that many fish tag values were close to Unit I line indicating that calculated maximum discharge residence times for these fish will be nearly 100 percent of the elapsed time

Anisotropic Interactions between Cold Rydberg Atoms

Science.gov (United States)

2015-09-28

AFRL-AFOSR-CL-TR-2015-0002 Anisotropic interactions between cold Rydberg atoms Luis Marcassa INSTITUTO DE FISICA DE SAO CARLOS Final Report 09/28...problem with the report +551633739806 Organization / Institution name Instituto de Fisica de Sao Carlos Grant/Contract Title The full title of the

Doppler time-of-flight imaging

KAUST Repository

Heidrich, Wolfgang; Heide, Felix; Wetzstein, Gordon; Hullin, Matthias

2017-01-01

Systems and methods for imaging object velocity are provided. In an embodiment, at least one Time-of-Flight camera is used to capture a signal representative of an object in motion over an exposure time. Illumination and modulation frequency

Calculation of Rydberg interaction potentials

DEFF Research Database (Denmark)

Weber, Sebastian; Tresp, Christoph; Menke, Henri

2017-01-01

for calculating the required electric multipole moments and the inclusion of electromagnetic fields with arbitrary direction. We focus specifically on symmetry arguments and selection rules, which greatly reduce the size of the Hamiltonian matrix, enabling the direct diagonalization of the Hamiltonian up...... to higher multipole orders on a desktop computer. Finally, we present example calculations showing the relevance of the full interaction calculation to current experiments. Our software for calculating Rydberg potentials including all features discussed in this tutorial is available as open source....

Focusing procedures in time-of-flight mass spectrometry

International Nuclear Information System (INIS)

Ioanoviciu, D.

2002-01-01

Time-of-flight mass spectrometry is a fast growing field due to its ability to handle very fast processes and due to its theoretically unlimited mass range. The performances of the time-of-flight mass analysers are heavily dependent on the progress in ion optics, a periodically reviewed field. In this presentation the various focusing procedures in time-of-flight mass spectrometry are reviewed. For ions of the same charge and mass flight time differences result from different potentials at the location of formation and from the initial velocity spread. There is no simultaneous space and velocity focusing in time-of-flight mass spectrometry. Space focusing of first and second order can be reached in time-of-flight mass analysers having two homogeneous electric field ion sources followed by a field free space in front of the detector. Single and double stage homogeneous electric field mirrors can focus in time ions of different energies. These different energies result when ions leaving different initial sites and arriving simultaneously to an intermediate space focus. Convenient mass dispersion can be obtained by including a mirror. Initial velocity focusing is obtained by the delayed extraction procedure in drift space and mirror time-of-flight mass analysers. Post source pulse focusing aims at the same purpose. Ion source electrodes of hyperbolic shape, operated by high voltage pulses can bring major improvements of the resolution, especially at high masses. For each focusing procedure the geometric and/or electric conditions are given as well as the aberrations allowing the mass resolution determination. The various focusing procedures are compared and a prediction of their future performances was tempted. (author)

Fermionic Collective Excitations in a Lattice Gas of Rydberg Atoms

International Nuclear Information System (INIS)

Olmos, B.; Gonzalez-Ferez, R.; Lesanovsky, I.

2009-01-01

We investigate the many-body quantum states of a laser-driven gas of Rydberg atoms confined to a large spacing ring lattice. If the laser driving is much stronger than the van der Waals interaction among the Rydberg atoms, these many-body states are collective fermionic excitations. The first excited state is a spin wave that extends over the entire lattice. We demonstrate that our system permits us to study fermions in the presence of disorder although no external atomic motion takes place. We analyze how this disorder influences the excitation properties of the fermionic states. Our work shows a route towards the creation of complex many-particle states with atoms in lattices.

Time Manager Software for a Flight Processor

Science.gov (United States)

Zoerne, Roger

2012-01-01

Data analysis is a process of inspecting, cleaning, transforming, and modeling data to highlight useful information and suggest conclusions. Accurate timestamps and a timeline of vehicle events are needed to analyze flight data. By moving the timekeeping to the flight processor, there is no longer a need for a redundant time source. If each flight processor is initially synchronized to GPS, they can freewheel and maintain a fairly accurate time throughout the flight with no additional GPS time messages received. How ever, additional GPS time messages will ensure an even greater accuracy. When a timestamp is required, a gettime function is called that immediately reads the time-base register.

ALICE Time of Flight Module

CERN Multimedia

The Time-Of-Flight system of ALICE consists of 90 such modules, each containing 15 or 19 Multigap Resistive Plate Chamber (MRPC) strips. This detector is used for identification of charged particles. It measures with high precision (50 ps) the time of flight of charged particles and therefore their velocity. The curvature of the particle trajectory inside the magnetic field gives the momentum, thus the particle mass is calculated and the particle is identified The MRPC is a stack of resistive glass plates, separated from each other by nylon fishing line. The mass production of the chambers (~1600, covering a surface of 150 m2) was done at INFN Bologna, while the first prototypes were bult at CERN.

ALICE Time Of Flight Detector

CERN Multimedia

Alici, A

2013-01-01

Charged particles in the intermediate momentum range are identified in ALICE by the Time Of Flight (TOF) detector. The time measurement with the TOF, in conjunction with the momentum and track length measured by the tracking detector, is used to calculate the particle mass.

Rydberg Molecules for Ion-Atom Scattering in the Ultracold Regime.

Science.gov (United States)

Schmid, T; Veit, C; Zuber, N; Löw, R; Pfau, T; Tarana, M; Tomza, M

2018-04-13

We propose a novel experimental method to extend the investigation of ion-atom collisions from the so far studied cold, essentially classical regime to the ultracold, quantum regime. The key aspect of this method is the use of Rydberg molecules to initialize the ultracold ion-atom scattering event. We exemplify the proposed method with the lithium ion-atom system, for which we present simulations of how the initial Rydberg molecule wave function, freed by photoionization, evolves in the presence of the ion-atom scattering potential. We predict bounds for the ion-atom scattering length from ab initio calculations of the interaction potential. We demonstrate that, in the predicted bounds, the scattering length can be experimentally determined from the velocity of the scattered wave packet in the case of ^{6}Li^{+}-^{6}Li and from the molecular ion fraction in the case of ^{7}Li^{+}-^{7}Li. The proposed method to utilize Rydberg molecules for ultracold ion-atom scattering, here particularized for the lithium ion-atom system, is readily applicable to other ion-atom systems as well.

Ultrafast non-adiabatic dynamics of methyl substituted ethylenes: The π3s Rydberg state

Science.gov (United States)

Wu, Guorong; Boguslavskiy, Andrey E.; Schalk, Oliver; Schuurman, Michael S.; Stolow, Albert

2011-10-01

Excited state unimolecular reactions of some polyenes exhibit localization of their dynamics at a single ethylenic double bond. Here we present studies of the fundamental photophysical processes in the ethylene unit itself. Combined femtosecond time-resolved photoelectron spectroscopy (TRPES) and ab initio quantum chemical calculations was applied to the study of excited state dynamics in cis-butene, trans-butene, trimethylethylene, and tetramethylethylene, following initial excitation to their respective π3s Rydberg states. The wavelength dependence of the π3s Rydberg state dynamics of tetramethylethylene was investigated in more detail. The π3s Rydberg to ππ* valence state decay rate varies greatly with substituent: the 1,2-di- and tri-methyl substituted ethylenes (cis-butene, trans-butene, and trimethylethylene) show an ultrafast decay (˜20 fs), whereas the fully methylated tetramethylethylene shows a decay rate of 2 to 4 orders of magnitude slower. These observations are rationalized in terms of topographical trends in the relevant potential energy surfaces, as found from ab initio calculations: (1) the barrier between the π3s state and the ππ* state increases with increasing methylation, and (2) the π3s/ππ* minimum energy conical intersection displaces monotonically away from the π3s Franck-Condon region with increasing methylation. The use of systematic methylation in combination with TRPES and ab initio computation is emerging as an important tool in discerning the excited state dynamics of unsaturated hydrocarbons.

Mean-field energy-level shifts and dielectric properties of strongly polarized Rydberg gases

OpenAIRE

Zhelyazkova, V.; Jirschik, R.; Hogan, S. D.

2016-01-01

Mean-field energy-level shifts arising as a result of strong electrostatic dipole interactions within dilute gases of polarized helium Rydberg atoms have been probed by microwave spectroscopy. The Rydberg states studied had principal quantum numbers n=70 and 72, and electric dipole moments of up to 14 050 D, and were prepared in pulsed supersonic beams at particle number densities on the order of 108 cm−3. Comparisons of the experimental data with the results of Monte Carlo calculations highl...

The TORCH time-of-flight detector

Energy Technology Data Exchange (ETDEWEB)

Harnew, N., E-mail: Neville.Harnew@physics.ox.ac.uk [University of Oxford, Denys Wilkinson Building, 1 Keble Road, Oxford OX1 3RH (United Kingdom); Brook, N. [University College London, Department of Physics & Astronomy, Gower Street, London WC1E 6BT (United Kingdom); Castillo García, L. [CERN, PH Department, CH-1211 Geneva 23 (Switzerland); Laboratory for High Energy Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Cussans, D. [H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); Föhl, K.; Forty, R.; Frei, C. [CERN, PH Department, CH-1211 Geneva 23 (Switzerland); Gao, R. [University of Oxford, Denys Wilkinson Building, 1 Keble Road, Oxford OX1 3RH (United Kingdom); Gys, T.; Piedigrossi, D. [CERN, PH Department, CH-1211 Geneva 23 (Switzerland); Rademacker, J.; Ros Garcia, A.; Dijk, M. van [H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom)

2016-07-11

The TORCH time-of-flight detector is being developed to provide particle identification between 2 and 10 GeV/c momentum over a flight distance of 10 m. TORCH is designed for large-area coverage, up to 30 m{sup 2}, and has a DIRC-like construction. The goal is to achieve a 15 ps time-of-flight resolution per incident particle by combining arrival times from multiple Cherenkov photons produced within quartz radiator plates of 10 mm thickness. A four-year R&D programme is underway with an industrial partner (Photek, UK) to produce 53×53 mm{sup 2} Micro-Channel Plate (MCP) detectors for the TORCH application. The MCP-PMT will provide a timing accuracy of 40 ps per photon and it will have a lifetime of up to at least 5 Ccm{sup −2} of integrated anode charge by utilizing an Atomic Layer Deposition (ALD) coating. The MCP will be read out using charge division with customised electronics incorporating the NINO chipset. Laboratory results on prototype MCPs are presented. The construction of a prototype TORCH module and its simulated performance are also described.

Ionization of H Rydberg atoms

International Nuclear Information System (INIS)

Hillermier, C.F.; Bluemental, R.; Smilansky, U.

1991-07-01

Concepts from the theory of transient chaos are applied to study the classical ionization process of one dimensional model of kicked hydrogen Rydberg atoms. The phase-space dynamics is represented by a mapping T which is proved to be hyperbolic. The fraction of atoms not ionized after time t, P B (t), decays asymptotically according to P B (t)∼t -α with α ∼ 1.65. The observed algebraic decay, which seems to contradict the hyperbolicity of T, is explained by (i) the symbolic dynamics of T consists of a countably infinite number of symbols and (ii) the invariant manifold of phase-space points which never ionize is an anomalously scaling fractal. Therefore, the one-dimensional kicked hydrogen atom provides a counterexample to the hypothesis that algebraic decay marks regular dynamics, whereas hyperbolic systems decay exponentially. The algebraic decay is reproduced by an analytically solvable diffusion model which predicts α = 3/2. Replacing zero-width δ-kicks by smooth finite-width pulses, the mapping T is no longer completely hyperbolic, and a subset of phase-space is regular. For this case we observe that P B (t) shows a transition between two power-law decays with α ∼ 1.65 for short times and α ∼ 2.1 for long times where the effect of the regular domain is felt. (author)

Mesoscopic Rydberg Gate Based on Electromagnetically Induced Transparency

International Nuclear Information System (INIS)

Mueller, M.; Lesanovsky, I.; Zoller, P.; Weimer, H.; Buechler, H. P.

2009-01-01

We demonstrate theoretically a parallelized C-NOT gate which allows us to entangle a mesoscopic ensemble of atoms with a single control atom in a single step, with high fidelity and on a microsecond time scale. Our scheme relies on the strong and long-ranged interaction between Rydberg atoms triggering electromagnetically induced transparency. By this we can robustly implement a conditional transfer of all ensemble atoms between two logical states, depending on the state of the control atom. We outline a many-body interferometer which allows a comparison of two many-body quantum states by performing a measurement of the control atom.

Data for analysis of mannose-6-phosphate glycans labeled with fluorescent tags

Directory of Open Access Journals (Sweden)

Ji-Yeon Kang

2016-06-01

Full Text Available Mannose-6-phosphate (M-6-P glycan plays an important role in lysosomal targeting of most therapeutic enzymes for treatment of lysosomal storage diseases. This article provides data for the analysis of M-6-P glycans by high-performance liquid chromatography (HPLC and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF mass spectrometry. The identities of M-6-P glycan peaks in HPLC profile were confirmed by measuring the masses of the collected peak eluates. The performances of three fluorescent tags (2-aminobenzoic acid [2-AA], 2-aminobenzamide [2-AB], and 3-(acetyl-amino-6-aminoacridine [AA-Ac] were compared focusing on the analysis of bi-phosphorylated glycan (containing two M-6-Ps. The bi-phosphorylated glycan analysis is highly affected by the attached fluorescent tag and the hydrophilicity of elution solvent used in HPLC. The data in this article is associated with the research article published in “Comparison of fluorescent tags for analysis of mannose-6-phosphate glycans” (Kang et al., 2016 [1].

Molecular ions, Rydberg spectroscopy and dynamics

International Nuclear Information System (INIS)

Jungen, Ch.

2015-01-01

Ion spectroscopy, Rydberg spectroscopy and molecular dynamics are closely related subjects. Multichannel quantum defect theory is a theoretical approach which draws on this close relationship and thereby becomes a powerful tool for the study of systems consisting of a positively charged molecular ion core interacting with an electron which may be loosely bound or freely scattering

Molecular ions, Rydberg spectroscopy and dynamics

Energy Technology Data Exchange (ETDEWEB)

Jungen, Ch. [Laboratoire Aimé Cotton, Université de Paris-Sud, 91405 Orsay (France)

2015-01-22

Ion spectroscopy, Rydberg spectroscopy and molecular dynamics are closely related subjects. Multichannel quantum defect theory is a theoretical approach which draws on this close relationship and thereby becomes a powerful tool for the study of systems consisting of a positively charged molecular ion core interacting with an electron which may be loosely bound or freely scattering.

Analytical properties of time-of-flight PET data

Energy Technology Data Exchange (ETDEWEB)

Cho, Sanghee; Ahn, Sangtae; Quanzheng, Li; Leahy, Richard M [Signal and Image Processing Institute, University of Southern California, Los Angeles, CA 90089 (United States)], E-mail: leahy@sipi.usc.edu

2008-06-07

We investigate the analytical properties of time-of-flight (TOF) positron emission tomography (PET) sinograms, where the data are modeled as line integrals weighted by a spatially invariant TOF kernel. First, we investigate the Fourier transform properties of 2D TOF data and extend the 'bow-tie' property of the 2D Radon transform to the time-of-flight case. Second, we describe a new exact Fourier rebinning method, TOF-FOREX, based on the Fourier transform in the time-of-flight variable. We then combine TOF-FOREX rebinning with a direct extension of the projection slice theorem to TOF data, to perform fast 3D TOF PET image reconstruction. Finally, we illustrate these properties using simulated data.

Analytical properties of time-of-flight PET data

Science.gov (United States)

Cho, Sanghee; Ahn, Sangtae; Li, Quanzheng; Leahy, Richard M.

2008-06-01

We investigate the analytical properties of time-of-flight (TOF) positron emission tomography (PET) sinograms, where the data are modeled as line integrals weighted by a spatially invariant TOF kernel. First, we investigate the Fourier transform properties of 2D TOF data and extend the 'bow-tie' property of the 2D Radon transform to the time-of-flight case. Second, we describe a new exact Fourier rebinning method, TOF-FOREX, based on the Fourier transform in the time-of-flight variable. We then combine TOF-FOREX rebinning with a direct extension of the projection slice theorem to TOF data, to perform fast 3D TOF PET image reconstruction. Finally, we illustrate these properties using simulated data.

Analytical properties of time-of-flight PET data

International Nuclear Information System (INIS)

Cho, Sanghee; Ahn, Sangtae; Li Quanzheng; Leahy, Richard M

2008-01-01

We investigate the analytical properties of time-of-flight (TOF) positron emission tomography (PET) sinograms, where the data are modeled as line integrals weighted by a spatially invariant TOF kernel. First, we investigate the Fourier transform properties of 2D TOF data and extend the 'bow-tie' property of the 2D Radon transform to the time-of-flight case. Second, we describe a new exact Fourier rebinning method, TOF-FOREX, based on the Fourier transform in the time-of-flight variable. We then combine TOF-FOREX rebinning with a direct extension of the projection slice theorem to TOF data, to perform fast 3D TOF PET image reconstruction. Finally, we illustrate these properties using simulated data

Analytical properties of time-of-flight PET data

Energy Technology Data Exchange (ETDEWEB)

Cho, Sanghee; Ahn, Sangtae; Li Quanzheng; Leahy, Richard M [Signal and Image Processing Institute, University of Southern California, Los Angeles, CA 90089 (United States)], E-mail: leahy@sipi.usc.edu

2008-06-07

We investigate the analytical properties of time-of-flight (TOF) positron emission tomography (PET) sinograms, where the data are modeled as line integrals weighted by a spatially invariant TOF kernel. First, we investigate the Fourier transform properties of 2D TOF data and extend the 'bow-tie' property of the 2D Radon transform to the time-of-flight case. Second, we describe a new exact Fourier rebinning method, TOF-FOREX, based on the Fourier transform in the time-of-flight variable. We then combine TOF-FOREX rebinning with a direct extension of the projection slice theorem to TOF data, to perform fast 3D TOF PET image reconstruction. Finally, we illustrate these properties using simulated data.

Motion of Rydberg atoms with strong permanent-electric-dipole interactions

International Nuclear Information System (INIS)

Gonçalves, Luís Felipe; Thaicharoen, Nithiwadee; Raithel, Georg

2016-01-01

Using classical trajectories simulations, we investigate the dynamics of a cold sample of Rydberg atoms with high permanent electric dipole moments. The dipolar state can be created using an adiabatic passage through an avoided crossing between an S-like state and a linear Stark state. The simulations yield the pair-correlation functions (PCF) of the atom samples, which allow us to extract the motion of Rydberg-atom pairs in the many-body system. The results reveal the strength and the anisotropic character of the underlying interaction. The simulation is employed to test the suitability of experimental methods designed to derive interaction parameters from PCF. Insight is obtained about the stability of the method against variation of experimentally relevant parameters. Transient correlations due to interaction-induced heating are observed. (paper)

Timing properties of a time-of-flight detector

International Nuclear Information System (INIS)

Nakagawa, Takahide; Yuasa-Nakagawa, Keiko.

1989-01-01

The time resolution of a time-of-flight (T.O.F.) detector which consists of a channel plate detector (CPD) with a central hole and a surface barrier detector (SBD) was measured. A time resolution of 80 psec fwhm was obtained for 8.78 MeV alpha particles. The influence on fast timing of the SBD of alpha particles was carefully studied. The plasma delay time and time resolution of the SBD were found to strongly depend on the electric field strength and properties of the SBD. (author)

The l-mixing cross section of Rydberg states of atomic Rb and the scaling LAW

International Nuclear Information System (INIS)

Liu Hong; Chen Aiqiu; Li Baiwen

1991-01-01

On the basis of impulse approximate method, a kind of analytical wavefunctions based on a potential model was used to calculate the l mixing cross section of thermal collision of Rydberg states of atomic Rb with rare gas (He, Ne). The results were compared with the experimental results and other theoretical values. These results show that there exists a kind of scaling law for the l mixing cross section of Rydberg alkali atoms

Laser diagnostics of the energy spectrum of Rydberg states of the lithium-7 atom

Energy Technology Data Exchange (ETDEWEB)

Zelener, B. B., E-mail: bobozel@mail.ru; Saakyan, S. A.; Sautenkov, V. A.; Manykin, E. A.; Zelener, B. V.; Fortov, V. E. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2015-12-15

The spectra of excited lithium-7 atoms prepared in a magneto-optical trap are studied using a UV laser. The laser diagnostics of the energy of Rydberg atoms is developed based on measurements of the change in resonance fluorescence intensity of ultracold atoms as the exciting UV radiation frequency passes through the Rydberg transition frequency. The energies of various nS configurations are obtained in a broad range of the principal quantum number n from 38 to 165. The values of the quantum defect and ionization energy obtained in experiments and predicted theoretically are discussed.

Mass cytometry: technique for real time single cell multitarget immunoassay based on inductively coupled plasma time-of-flight mass spectrometry.

Science.gov (United States)

Bandura, Dmitry R; Baranov, Vladimir I; Ornatsky, Olga I; Antonov, Alexei; Kinach, Robert; Lou, Xudong; Pavlov, Serguei; Vorobiev, Sergey; Dick, John E; Tanner, Scott D

2009-08-15

A novel instrument for real time analysis of individual biological cells or other microparticles is described. The instrument is based on inductively coupled plasma time-of-flight mass spectrometry and comprises a three-aperture plasma-vacuum interface, a dc quadrupole turning optics for decoupling ions from neutral components, an rf quadrupole ion guide discriminating against low-mass dominant plasma ions, a point-to-parallel focusing dc quadrupole doublet, an orthogonal acceleration reflectron analyzer, a discrete dynode fast ion detector, and an 8-bit 1 GHz digitizer. A high spectrum generation frequency of 76.8 kHz provides capability for collecting multiple spectra from each particle-induced transient ion cloud, typically of 200-300 micros duration. It is shown that the transients can be resolved and characterized individually at a peak frequency of 1100 particles per second. Design considerations and optimization data are presented. The figures of merit of the instrument are measured under standard inductively coupled plasma (ICP) operating conditions ( 900 for m/z = 159, the sensitivity with a standard sample introduction system of >1.4 x 10(8) ion counts per second per mg L(-1) of Tb and an abundance sensitivity of (6 x 10(-4))-(1.4 x 10(-3)) (trailing and leading masses, respectively) are shown. The mass range (m/z = 125-215) and abundance sensitivity are sufficient for elemental immunoassay with up to 60 distinct available elemental tags. When 500) can be used, which provides >2.4 x 10(8) cps per mg L(-1) of Tb, at (1.5 x 10(-3))-(5.0 x 10(-3)) abundance sensitivity. The real-time simultaneous detection of multiple isotopes from individual 1.8 microm polystyrene beads labeled with lanthanides is shown. A real time single cell 20 antigen expression assay of model cell lines and leukemia patient samples immuno-labeled with lanthanide-tagged antibodies is presented.

Orbital alignment effects in near-resonant Rydberg atoms-rare gas collisions

International Nuclear Information System (INIS)

Isaacs, W.A.; Morrison, M.A.

1993-01-01

Recent experimental and theoretical studies of near-resonant energy transfer collisions involving rare-gas atoms and alkali or alkaline earth atoms which have been initially excited to an aligned state via one or more linearly polarized rasters have yielded a wealth of insight into orbital alignment and related effects. We have extended this inquiry to initially aligned Rydberg states, examining state-to-state and alignment-selected cross sections using quantum collision theory augmented by approximations appropriate to the special characteristics of the Rydberg state (e.g., the quasi-free-electron model and the impulse approximation)

Tag-elese or The Language of Tags

Directory of Open Access Journals (Sweden)

Jan Simons

2008-01-01

Full Text Available The core "meme" of Web 2.0 from which almost all other memes radiated was: 'You control your own data' (O'Reilly, 2005, 3. Key instruments for this user control are tagging systems that allow users to freely assign keywords of their own choosing to Internet resources of their own making as well as to documents produced by others. Of course, freely chosen keywords tags do not necessarily follow prefixed taxonomies or classification systems. But going by the maxim that interaction creates similarity and similarity creates interaction, the idea - or hope - is, however, that the tagging practices of individual users will eventually converge into an emergent common vocabulary or folksonomy (Merholz, 2004; Shirky, 2005; Vander Wal, 2005b; Mika, 2007. It is far from clear, however, that free tagging systems will eventually yield controlled vocabularies, and there are many incentives for idiosyncratic, ambiguous, and inconsistent uses of tags. Left to themselves, free tagging systems seem to be too wild and too chaotic for any order to emerge. But are these free tagging systems really as "feral" as they seem to be, or do they only look uncontrolled because one has been looking for order in the wrong place? I have done a quick-and-dirty" analysis of Flickr's tag cloud. The concept was: if folksonomies encourage users to tap on their own vernacular, everyday natural language must somehow "guide" the tagging practices of users of tagging systems. Flickr's tag cloud has been choosen because it may teach us something about tagging systems and folksonomies, and not - or not primarily - because of what tags may tell us about pictures.

The population transfer of high excited states of Rydberg lithium atoms in a microwave field

International Nuclear Information System (INIS)

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

2012-01-01

Using the time-dependent multilevel approach (TDMA), the properties of high excited Rydberg lithium atom have been obtained in the microwave field. The population transfer of lithium atom are studied on numerical calculation, quantum states are controlled and manipulated by microwave field. It shows that the population can be completely transferred to the target state by changing the chirped rate and field amplitude. (authors)

Population coherent control of Rydberg potassium atom via adiabatic passage

International Nuclear Information System (INIS)

Jiang Li-Juan; Zhang Xian-Zhou; Jia Guang-Rui; Zhang Yong-Hui; Xia Li-Hua

2013-01-01

The time-dependent multilevel approach (TDMA) and B-spline expansion technique are used to study the coherent population transfer between the quantum states of a potassium atom by a single frequency-chirped microwave pulse. The Rydberg potassium atom energy levels of n = 6–15, l = 0–5 states in zero field are calculated and the results are in good agreement with other theoretical values. The time evolutions of the population transfer of the six states from n = 70 to n = 75 in different microwave fields are obtained. The results show that the coherent control of the population transfer from the lower states to the higher ones can be accomplished by optimizing the microwave pulse parameters. (atomic and molecular physics)

Time-of-flight experiments using a pseudo-statistical chopper

International Nuclear Information System (INIS)

Aizawa, Otohiko; Kanda, Keiji

1975-01-01

A ''pseudo-statistical'' chopper was manufactured and used for the experiments on neutron transmission and scattering. The characteristics of the chopper and the experimental results are discussed in comparison with those in the time-of-flight technique using a conventional chopper. Which of the two methods is superior depends on the form of the time-of-flight distribution to be measured. Pseudo-statistical pulsing may be especially advantageous for scattering experiments with single or a few-line time-of-flight spectrum. (auth.)

Hydrogen Balmer series measurements and determination of Rydberg's constant using two different spectrometers

International Nuclear Information System (INIS)

Amrani, D

2014-01-01

This paper investigates the use of two different methods, the optical and the computer-aided diffraction-grating spectrometer, to measure the wavelength of visible lines of Balmer series from the hydrogen atomic spectrum and estimate the value of Rydberg's constant. Analysis and interpretation of data showed that both methods, despite their difference in terms of the type of equipment used, displayed good performance in terms of precision of measurements of wavelengths of spectral lines. A comparison was carried out between the experimental value of Rydberg's constant obtained with both methods and the accepted value. The results of Rydberg's constant obtained with both the optical and computer-aided spectrometers were 1.099 28 × 10 −7  m −1  and 1.095 13 × 10 −7  m −1  with an error difference of 0.17% and 0.20% compared to the accepted value 1.097 373 × 10 −7  m −1 , respectively. (paper)

Electronic structure of molecular Rydberg states of some small molecules and molecular ion

International Nuclear Information System (INIS)

Sun Biao; Li Jiaming

1993-01-01

Based on an independent-particle-approximation (i.e. the multiple scattering self-consistent-field theory), the electronic structures of Rydberg states of the small diatomic molecules H 2 , He 2 and the He 2 + molecular ion were studied. The principal quantum number of the first state of the Rydberg series is determined from a convention of the limit of the molecular electronic configuration. The dynamics of the excited molecules and molecular ion has been elucidated. The theoretical results are in fair agreement with the existing experimental measurements, thus they can serve as a reliable basis for future refined treatment such as the configuration interaction calculation

New innershell phenomena from Rydberg series of highly charged ions

International Nuclear Information System (INIS)

Rosmej, F.B.

1997-01-01

Dielectronic satellite spectra near the He-like resonance line W are investigated experimentally and theoretically. We propose that under certain plasma conditions the resonance line structure plays a minor role and can be mixed with the accumulation of Rydberg satellites. (orig.)

From the Rydberg constant to the fundamental constants metrology; De la constante de Rydberg a la metrologie des constantes fondamentales

Energy Technology Data Exchange (ETDEWEB)

Nez, F

2005-06-15

This document reviews the theoretical and experimental achievements of the author since the beginning of his scientific career. This document is dedicated to the spectroscopy of hydrogen, deuterium and helium atoms. The first part is divided into 6 sub-sections: 1) the principles of hydrogen spectroscopy, 2) the measurement of the 2S-nS/nD transitions, 3) other optical frequency measurements, 4) our contribution to the determination of the Rydberg constant, 5) our current experiment on the 1S-3S transition, 6) the spectroscopy of the muonic hydrogen. Our experiments have improved the accuracy of the Rydberg Constant by a factor 25 in 15 years and we have achieved the first absolute optical frequency measurement of a transition in hydrogen. The second part is dedicated to the measurement of the fine structure constant and the last part deals with helium spectroscopy and the search for optical references in the near infrared range. (A.C.)

Semiclassical analysis of quantum localization of the periodically kicked Rydberg atom

International Nuclear Information System (INIS)

Yoshida, S.; Persson, E.; Burgdoerfer, J.; Grossmann, F.

2004-01-01

The periodically kicked Rydberg atom displays quantum localization, features of which depend on the orientation and strength of the unidirectional kicks. They include scarring of the wave function, localization by cantori, and exponential localization in the regime of strong perturbation resembling dynamical localization. Using the semiclassical Herman-Kluk propagator we investigate the degree to which semiclassical dynamics can mimic quantum localization. While the semiclassical approximation has difficulties to reproduce the scarred wave functions, the exponential tail which is a typical signature of the dynamical localization is well represented in the case of strong classical diffusion. Also the localization by broken tori is observed in the semiclassical recurrence probability for short times but the deviation from the corresponding quantum dynamics becomes more pronounced for the long-time evolution

n l -> n' l' transition rates in electron and proton - Rydberg atom collision

Science.gov (United States)

Vrinceanu, Daniel

2017-04-01

Electrons and protons drive the recombination dynamics of highly excited Rydberg atoms in cold rarefied plasmas found in astrophysical conditions such as primordial recombination or star formation in H-II clouds. It has been recognized that collisions induce both energy and angular momentum transitions in Rydberg atoms, although in different proportions, depending on the initial state, temperature and the given species considered in the collision (electron or proton). Most studies focused on one collision type at a time, under the assumption that collision types are independent or their effects are not competing. The classical Monte-Carlo trajectory simulations presented in this work calculate the rates for both energy and angular momentum transfers and show their interdependence. For example, energy transfer with small angular momentum change are more efficient for target states with initial large angular momentum. The author acknowledges support received from the National Science Foundation through a Grant for the Center for Research on Complex Networks (HRD-1137732).

Monoacylglycerol Analysis Using MS/MSALL Quadruple Time of Flight Mass Spectrometry

Directory of Open Access Journals (Sweden)

Fei Gao

2016-08-01

Full Text Available Monoacylglycerols (MAGs are structural and bioactive metabolites critical for biological function. Development of facile tools for measuring MAG are essential to understand its role in different diseases and various pathways. A data-independent acquisition method, MS/MSALL, using electrospray ionization (ESI coupled quadrupole time of flight mass spectrometry (MS, was utilized for the structural identification and quantitative analysis of individual MAG molecular species. Compared with other acylglycerols, diacylglycerols (DAG and triacylglycerols (TAG, MAG characteristically presented as a dominant protonated ion, [M + H]+, and under low collision energy as fatty acid-like fragments due to the neutral loss of the glycerol head group. At low concentrations (<10 pmol/µL, where lipid-lipid interactions are rare, there was a strong linear correlation between ion abundance and MAG concentration. Moreover, using the MS/MSALL method the major MAG species from human plasma and mouse brown and white adipose tissues were quantified in less than 6 min. Collectively, these results demonstrate that MS/MSALL analysis of MAG is an enabling strategy for the direct identification and quantitative analysis of low level MAG species from biological samples with high throughput and sensitivity.

Strong enhancement of Penning ionization for asymmetric atom pairs in cold Rydberg gases: the Tom and Jerry effect

KAUST Repository

Efimov, D K

2016-05-18

We consider Penning ionization of Rydberg atom pairs as an Auger-type process induced by the dipole-dipole interaction and employ semiclassical formulae for dipole transitions to calculate the autoionization width as a function of the principal quantum numbers, n d, n i, of both atoms. While for symmetric atom pairs with the well-known increase of the autoionization width with increasing n 0 is obtained, the result for asymmetric pairs is counterintuitive - for a fixed n i of the ionizing atom of the pair, the autoionization width strongly increases with decreasing n d of the de-excited atom. For H Rydberg atoms this increase reaches two orders of magnitude at the maximum of the n d dependence, and the same type of counterintuitive behavior is exhibited also by Na, Rb and Cs atoms. This is a purely quantum-mechanical effect, which points towards existence of optimal (we call them \\'Tom\\' and \\'Jerry\\' for \\'big\\' and \\'small\\') pairs of Rydberg atoms with respect to autoionization efficiency. Building on the model of population redistribution in cold Rydberg gases proposed in [1], we demonstrate that population evolution following the initial laser excitation of Rydberg atoms in state n 0 would eventually lead to the formation of such Tom-Jerry pairs with which feature autoionization widths that are enhanced by several orders of magnitude compared to that of two atoms in the initial laser-excited state n 0. We also show that in the high-density regime of cold Rydberg gas experiments the ionization rate of Tom-Jerry pairs can be substantially larger than the blackbody radiation-induced photoionization rate. © 2016 IOP Publishing Ltd.

New innershell phenomena from Rydberg series of highly charged ions

Energy Technology Data Exchange (ETDEWEB)

Rosmej, F.B. [Bochum Univ. (Germany). Inst. fuer Experimentalphysik; Faenov, A.Ya. [MISDC, VNIIFTRI, Mendeleevo (Russian Federation)

1997-12-31

Dielectronic satellite spectra near the He-like resonance line W are investigated experimentally and theoretically. We propose that under certain plasma conditions the resonance line structure plays a minor role and can be mixed with the accumulation of Rydberg satellites. (orig.). 7 refs.

Population of Rydberg states by electron capture in fast-ion--atom collisions

International Nuclear Information System (INIS)

Burgdoerfer, J.; Dube, L.J.

1985-01-01

The l,m-substate distribution in low-lying Rydberg manifolds (nroughly-equal10) following electron capture H + +H(1s)→H(n)+H + is calculated at high velocities (v>1 a.u.) in the continuum-distorted-wave (CDW) approximation. The standard CDW approximation is modified to account for final-state Stark mixing of the Rydberg manifold in the exit channel using the post-collision-interaction model. The influence of multiple-scattering contributions is analyzed and comparison is made with sigma/sub l/m predicted by the Born approximation. We find that the double-scattering contribution, closely connected with the classical Thomas process, becomes visible in the CDW approximation at surprisingly low nonasymptotic velocities

Photoionization microscopy of Rydberg hydrogen atom in a non-uniform electrical field

International Nuclear Information System (INIS)

Cheng Shao-Hao; Wang De-Hua; Chen Zhao-Hang; Chen Qiang

2016-01-01

In this paper, we investigate the photoionization microscopy of the Rydberg hydrogen atom in a gradient electric field for the first time. The observed oscillatory patterns in the photoionization microscopy are explained within the framework of the semiclassical theory, which can be considered as a manifestation of interference between various electron trajectories arriving at a given point on the detector plane. In contrast with the photoionization microscopy in the uniform electric field, the trajectories of the ionized electron in the gradient electric field will become chaotic. An infinite set of different electron trajectories can arrive at a given point on the detector plane, which makes the interference pattern of the electron probability density distribution extremely complicated. Our calculation results suggest that the oscillatory pattern in the electron probability density distribution depends sensitively on the electric field gradient, the scaled energy and the position of the detector plane. Through our research, we predict that the interference pattern in the electron probability density distribution can be observed in an actual photoionization microscopy experiment once the external electric field strength and the position of the electron detector plane are reasonable. This study provides some references for the future experimental research on the photoionization microscopy of the Rydberg atom in the non-uniform external fields. (paper)

Simple flight time calibration generator in PLL technique

International Nuclear Information System (INIS)

Lauch, J.

1975-01-01

Calibration and routine check-ups of flight time measuring systems can be carried out with the aid of defined flight time calibration spectra. This paper describes a simple flight time calibration generator capable of generating such calibration spectra in the form of line spectra or of a white spectrum. The flight time of the generator is adjustable in steps from 100 to 3,200 ns. The number of calibration lines can be set to 10 or to 20, resulting in line spacings ranging from 5 to 320 ns. The stop signals are generated by a crystal oscillator, the start signals are generated by a voltage-controlled oscillator locked in a phase control circuit. The start and stop rates can be adjusted in steps. (orig.) [de

Flow-Tagging Velocimetry for Hypersonic Flows Using Fluorescence of Nitric Oxide

Science.gov (United States)

Danehy, P. M.; OByrne, S.; Houwing, A. F. P.

2001-01-01

We investigate a new type of flow-tagging velocimetry technique for hypersonic flows. The technique involves exciting a thin line of nitric oxide molecules with a laser beam and then, after some delay, acquiring an image of the displaced line. One component of velocity is determined from the time of flight. This method is applied to measure the velocity profile in a Mach 8.5 laminar, hypersonic boundary layer in the Australian National Universities T2 free-piston shock tunnel. The velocity is measured with an uncertainty of approximately 2%. Comparison with a CFD simulation of the flow shows reasonable agreement.

Time coder for slow neutron time-of-flight spectrometer

International Nuclear Information System (INIS)

Grashilin, V.A.; Ofengenden, R.G.

1988-01-01

Time coder for slow neutron time-of-flight spectrometer is described. The time coder is of modular structure, is performed in the CAMAC standard and operates on line with DVK-2 computer. The main coder units include supporting generator, timers, time-to-digital converter, memory unit and crate controller. Method for measuring background symmetrically to the effect is proposed for a more correct background accounting. 4 refs.; 1 fig

An investigation of electronic states of some molecules and molecular cations using mass analyzed threshold ionization and photoinduced Rydberg ionization spectroscopy

Science.gov (United States)

Hofstein, Jason David

1999-11-01

Mass analyzed threshold ionization (MATI) experiments have enabled mapping of the n-dependent Rydberg state survival probability for a series of molecules. Utilizing vacuum and extreme ultraviolet (VUV/XUV) photons, one photon Rydberg manifold spectra of argon, hydrogen chloride, nitrogen, benzene, and oxygen were produced, and the prospects of photoinduced Rydberg ionization (PIRI) experiments examined. It was found that the widths of Rydberg manifolds for the molecules studied are quite different. Hydrogen chloride and nitrogen have the narrowest manifold width, followed by benzene, and then oxygen. These varying widths are most strongly correlated with the angular momentum (i.e., quantum defect) of the initially prepared Rydberg orbital. PIRI experiments required the use of a static cell, rather than a molecular jet assembly, for the more efficient production of higher amounts of VUV/XUV radiation, and hence more Rydberg signal needed to observe PIRI. Armed with the ability to produce tunable VUV/XUV radiation, and to determine the feasibility of a PIRI experiment, the MATI and fragment PIRI spectra of trans-1,3-butadiene (BD) were recorded. The MATI spectrum is vibrationally resolved and was analyzed with the help of ab initio calculations and other published results. The fragment PIRI spectrum of the Aproduction of C3H3+ dominates, but at higher photon energies, C2H4 + is also produced. The production of each fragment showed a definite PIRI wavelength dependence.

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.

Time-frequency energy density precipitation method for time-of-flight extraction of narrowband Lamb wave detection signals

Energy Technology Data Exchange (ETDEWEB)

Zhang, Y., E-mail: thuzhangyu@foxmail.com; Huang, S. L., E-mail: huangsling@tsinghua.edu.cn; Wang, S.; Zhao, W. [State Key Laboratory of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China)

2016-05-15

The time-of-flight of the Lamb wave provides an important basis for defect evaluation in metal plates and is the input signal for Lamb wave tomographic imaging. However, the time-of-flight can be difficult to acquire because of the Lamb wave dispersion characteristics. This work proposes a time-frequency energy density precipitation method to accurately extract the time-of-flight of narrowband Lamb wave detection signals in metal plates. In the proposed method, a discrete short-time Fourier transform is performed on the narrowband Lamb wave detection signals to obtain the corresponding discrete time-frequency energy density distribution. The energy density values at the center frequency for all discrete time points are then calculated by linear interpolation. Next, the time-domain energy density curve focused on that center frequency is precipitated by least squares fitting of the calculated energy density values. Finally, the peak times of the energy density curve obtained relative to the initial pulse signal are extracted as the time-of-flight for the narrowband Lamb wave detection signals. An experimental platform is established for time-of-flight extraction of narrowband Lamb wave detection signals, and sensitivity analysis of the proposed time-frequency energy density precipitation method is performed in terms of propagation distance, dispersion characteristics, center frequency, and plate thickness. For comparison, the widely used Hilbert–Huang transform method is also implemented for time-of-flight extraction. The results show that the time-frequency energy density precipitation method can accurately extract the time-of-flight with relative error of <1% and thus can act as a universal time-of-flight extraction method for narrowband Lamb wave detection signals.

Time-frequency energy density precipitation method for time-of-flight extraction of narrowband Lamb wave detection signals

International Nuclear Information System (INIS)

Zhang, Y.; Huang, S. L.; Wang, S.; Zhao, W.

2016-01-01

The time-of-flight of the Lamb wave provides an important basis for defect evaluation in metal plates and is the input signal for Lamb wave tomographic imaging. However, the time-of-flight can be difficult to acquire because of the Lamb wave dispersion characteristics. This work proposes a time-frequency energy density precipitation method to accurately extract the time-of-flight of narrowband Lamb wave detection signals in metal plates. In the proposed method, a discrete short-time Fourier transform is performed on the narrowband Lamb wave detection signals to obtain the corresponding discrete time-frequency energy density distribution. The energy density values at the center frequency for all discrete time points are then calculated by linear interpolation. Next, the time-domain energy density curve focused on that center frequency is precipitated by least squares fitting of the calculated energy density values. Finally, the peak times of the energy density curve obtained relative to the initial pulse signal are extracted as the time-of-flight for the narrowband Lamb wave detection signals. An experimental platform is established for time-of-flight extraction of narrowband Lamb wave detection signals, and sensitivity analysis of the proposed time-frequency energy density precipitation method is performed in terms of propagation distance, dispersion characteristics, center frequency, and plate thickness. For comparison, the widely used Hilbert–Huang transform method is also implemented for time-of-flight extraction. The results show that the time-frequency energy density precipitation method can accurately extract the time-of-flight with relative error of <1% and thus can act as a universal time-of-flight extraction method for narrowband Lamb wave detection signals.

Systematics in Rydberg state excitations for ion-atom collisions

International Nuclear Information System (INIS)

Andresen, B.; Jensen, K.; Petersen, N.B.; Veje, E.

1976-01-01

Rydberg state excitations in the Ne + , Mg + -He collisions have been studied in the projectile energy range 10-75 keV by means of optical spectrometry in a search for systematic trends. The relative excitation cross sections for levels of a Rydberg term series are found to follow a general (nsup(x))sup(P) behaviour with P < approximately -3 varying with collision energy and particles, regardless of whether the excited state population results from direct excitation, single electron transfer, or double electron transfer. At higher collision energies P is approximately -3 as predicted by theory. Polarization of the emitted line radiation indicates that there is no general rule for the relative excitation of the different magnetic substates of the same level. A statistical distribution of excitation is found for levels within the same term when the fine structure splitting is small. (Auth.)

Auto transfer to Rydberg states and indirect stabilization following double capture

Energy Technology Data Exchange (ETDEWEB)

Roncin, P.; Gaboriaud, M.N.; Barat, M. (Paris-11 Univ., 91 - Orsay (France)); Bordenave-Montesquieu, A.; Moretto-Capelle, P.; Benhenni, M. (Toulouse-3 Univ., 31 (France)); Bachau, H.; Harel, C. (Bordeaux-1 Univ., 33 (France))

1993-11-28

Two-electron capture by slow multiply charged ions colliding on rare-gas target at keV energies is known to populate doubly excited states of the projectile with large cross sections. Though these states are dominantly autoionizing, important radiative decay following double capture have been reported, among which the direct observation of the fluorescence from Rydberg states. A mechanism based on post-collisional effects was proposed, in which Rydberg states are fed from the quasi-symmetrical doubly excited states initially populated. In this paper, a quantitative analysis of this effect is developed leading to a simple model which is applied to N[sup 7+] on He and Ar collisions. (author).

Auto transfer to Rydberg states and indirect stabilization following double capture

International Nuclear Information System (INIS)

Roncin, P.; Gaboriaud, M.N.; Barat, M.; Bordenave-Montesquieu, A.; Moretto-Capelle, P.; Benhenni, M.; Bachau, H.; Harel, C.

1993-01-01

Two-electron capture by slow multiply charged ions colliding on rare-gas target at keV energies is known to populate doubly excited states of the projectile with large cross sections. Though these states are dominantly autoionizing, important radiative decay following double capture have been reported, among which the direct observation of the fluorescence from Rydberg states. A mechanism based on post-collisional effects was proposed, in which Rydberg states are fed from the quasi-symmetrical doubly excited states initially populated. In this paper, a quantitative analysis of this effect is developed leading to a simple model which is applied to N 7+ on He and Ar collisions. (author)

Dissipative preparation of steady Greenberger-Horne-Zeilinger states for Rydberg atoms with quantum Zeno dynamics

Science.gov (United States)

Shao, X. Q.; Wu, J. H.; Yi, X. X.; Long, Gui-Lu

2017-12-01

Inspired by a recent work [F. Reiter, D. Reeb, and A. S. Sørensen, Phys. Rev. Lett. 117, 040501 (2016), 10.1103/PhysRevLett.117.040501], we present a simplified proposal for dissipatively preparing a Greenberger-Horne-Zeilinger (GHZ) state of three Rydberg atoms in a cavity. The Z pumping is implemented under the action of the spontaneous emission of Λ -type atoms and the quantum Zeno dynamics induced by strong continuous coupling. In the meantime, a dissipative Rydberg pumping breaks up the stability of the state | GHZ+〉 in the process of Z pumping, making | GHZ-〉 the unique steady state of the system. Compared with the former scheme, the number of driving fields acting on atoms is greatly reduced and only a single-mode cavity is required. The numerical simulation of the full master equation reveals that a high fidelity ˜98 % can be obtained with the currently achievable parameters in the Rydberg-atom-cavity system.

IceBridge Riegl Laser Altimeter L1B Time-Tagged Laser Ranges

Data.gov (United States)

National Aeronautics and Space Administration — The NASA IceBridge Riegl Laser Altimeter L1B Time-Tagged Laser Ranges (ILUTP1B) data set contains laser ranges, returned pulses, and deviation for returned pulses in...

Ionization of nS, nP, and nD lithium, potassium, and cesium Rydberg atoms by blackbody radiation

Science.gov (United States)

Beterov, I. I.; Ryabtsev, I. I.; Tretyakov, D. B.; Bezuglov, N. N.; Ékers, A.

2008-07-01

The results of theoretical calculations of the blackbody ionization rates of lithium, potassium, and cesium atoms residing in Rydberg states are presented. The calculations are performed for nS, nP, and nD states in a wide range of principal quantum numbers, n = 8-65, for blackbody radiation temperatures T = 77, 300, and 600 K. The calculations are performed using the known quasi-classical formulas for the photoionization cross sections and for the radial matrix elements of transitions in the discrete spectrum. The effect of the blackbody-radiation-induced population redistribution between Rydberg states on the blackbody ionization rates measured under laboratory conditions is quantitatively analyzed. Simple analytical formulas that approximate the numerical results and that can be used to estimate the blackbody ionization rates of Rydberg atoms are presented. For the S series of lithium, the rate of population of high-lying Rydberg levels by blackbody radiation is found to anomalously behave as a function of n. This anomaly is similar to the occurrence of the Cooper minimum in the discrete spectrum.

The ARGUS time-of-flight system

International Nuclear Information System (INIS)

Heller, R.; Klinger, T.; Salomon, R.; Schubert, K.R.; Stiewe, J.; Waldi, R.; Weseler, S.

1985-01-01

The time-of-flight system of the ARGUS detector at the DORIS e + e - storage ring consists of 64 barrel scintillation counters covering 75% of 4π, and 2x48 end cap counters, covering 17% of 4π. The barrel counters are viewed by two phototubes each, while the end cap counters have one tube only. The time-of-flight system serves as a part of the fast trigger and identifies charged particles. The time resolution achieved during the first year of ARGUS operation is 210 ps for Bhabhas (which are used for the off-line monitoring of the system), and 220 ps for hadrons, both in barrel and end cap counters. This converts into a three standard deviation mass separation up to 700 MeV/c between pions and kaons and 1200 MeV/c between kaons and protons. Electrons can be separated from heavier particles up to 230 MeV/c. (orig.)

Dynamic polarizabilities and Rydberg states of the argon isoelectronic sequence

International Nuclear Information System (INIS)

Ghosh, T.K.; Das, A.K.; Castro, M.; Canuto, S.; Mukherjee, P.K.

1993-01-01

Dynamic dipole polarizabilities α d (ω) have been calculated within and beyond the normal-dispersion region for the isoelectronic members of argon up to Mn 7+ using time-dependent coupled Hartree-Fock theory. Excitation energies, oscillator strengths, and quantum-defect values have been estimated for the dipole-allowed transitions 3p 6 1 Se→3p 5 ( 2 P)ns 1 Po (n=4,...,7) and 3p 6 1 Se→3p 5 ( 2 P)nd 1 Po (n=3,...,7). Analytic representations of the singly excited Rydberg orbitals have been obtained. The results compare favorably with the existing theoretical and experimental data. The oscillator strengths show an interesting trend of variation along the isoelectronic sequence

Coherent excitation of a single atom to a Rydberg state

DEFF Research Database (Denmark)

Miroshnychenko, Yevhen; Gaëtan, Alpha; Evellin, Charles

2010-01-01

We present the coherent excitation of a single Rubidium atom to the Rydberg state 58d3/2 using a two-photon transition. The experimental setup is described in detail, as are experimental techniques and procedures. The coherence of the excitation is revealed by observing Rabi oscillations between...

Time-frequency energy density precipitation method for time-of-flight extraction of narrowband Lamb wave detection signals.

Science.gov (United States)

Zhang, Y; Huang, S L; Wang, S; Zhao, W

2016-05-01

The time-of-flight of the Lamb wave provides an important basis for defect evaluation in metal plates and is the input signal for Lamb wave tomographic imaging. However, the time-of-flight can be difficult to acquire because of the Lamb wave dispersion characteristics. This work proposes a time-frequency energy density precipitation method to accurately extract the time-of-flight of narrowband Lamb wave detection signals in metal plates. In the proposed method, a discrete short-time Fourier transform is performed on the narrowband Lamb wave detection signals to obtain the corresponding discrete time-frequency energy density distribution. The energy density values at the center frequency for all discrete time points are then calculated by linear interpolation. Next, the time-domain energy density curve focused on that center frequency is precipitated by least squares fitting of the calculated energy density values. Finally, the peak times of the energy density curve obtained relative to the initial pulse signal are extracted as the time-of-flight for the narrowband Lamb wave detection signals. An experimental platform is established for time-of-flight extraction of narrowband Lamb wave detection signals, and sensitivity analysis of the proposed time-frequency energy density precipitation method is performed in terms of propagation distance, dispersion characteristics, center frequency, and plate thickness. For comparison, the widely used Hilbert-Huang transform method is also implemented for time-of-flight extraction. The results show that the time-frequency energy density precipitation method can accurately extract the time-of-flight with relative error of wave detection signals.

Spin--orbit configuration-interaction study of valence and Rydberg states of LiBe

International Nuclear Information System (INIS)

Marino, M.M.; Ermler, W.C.; Kern, C.W.; Bondybey, V.E.

1992-01-01

Ab initio spin--orbit full configuration-interaction calculations in the context of relativistic effective core potentials are reported for the weakly bound metal dimer LiBe, a three-valence-electron system. The effects of basis set on the energies of valence and Rydberg states of the cluster are discussed, as are the effects of configuration space selection on the energy of the latter states. Results at the dissociative limit are compared to the experimental atomic spectra. Potential-energy curves and spectroscopic constants are presented for the ground state and fourteen excited states, which includes the Li and Be 2p valence states, the Li 3s, 3p, 3d, and 4s Rydberg states, as well as three low-lying states of the molecular cation

Ionization of Rydberg atoms by the kicks of half-cycle pulses

Indian Academy of Sciences (India)

2015-11-27

Home; Journals; Pramana – Journal of Physics; Volume 86; Issue 4. Ionization of Rydberg atoms by the kicks of half-cycle pulses ... Proceedings of the International Workshop/Conference on Computational Condensed Matter Physics and Materials Science (IWCCMP-2015). Posted on November 27, 2015. Guest Editors: ...

Lithium atoms on helium nanodroplets: Rydberg series and ionization dynamics

Science.gov (United States)

Lackner, Florian; Krois, Günter; Ernst, Wolfgang E.

2017-11-01

The electronic excitation spectrum of lithium atoms residing on the surface of helium nanodroplets is presented and analyzed employing a Rydberg-Ritz approach. Utilizing resonant two-photon ionization spectroscopy, two different Rydberg series have been identified: one assigned to the nS(Σ) series and the other with predominantly nP(Π) character. For high Rydberg states, which have been resolved up to n = 13, the surrounding helium effectively screens the valence electron from the Li ion core, as indicated by the apparent red-shift of Li transitions and lowered quantum defects on the droplet with respect to their free atom counterparts. For low n states, the screening effect is weakened and the prevailing repulsive interaction gives rise to strongly broadened and blue-shifted transitions. The red-shifts originate from the polarization of nearby He atoms by the positive Li ion core. As a consequence of this effect, the ionization threshold is lowered by 116 ± 10 cm-1 for Li on helium droplets with a radius of about 40 Å. Upon single-photon ionization, heavy complexes corresponding to Li ions attached to intact helium droplets are detected. We conclude that ionization close to the on-droplet ionization threshold triggers a dynamic process in which the Li ion core undergoes a transition from a surface site into the droplet.

Alkali Rydberg states in electromagnetic fields: computational physics meets experiment

International Nuclear Information System (INIS)

Krug, A.

2001-11-01

We study highly excited hydrogen and alkali atoms ('Rydberg states') under the influence of a strong microwave field. As the external frequency is comparable to the highly excited electron's classical Kepler frequency, the external field induces a strong coupling of many different quantum mechanical energy levels and finally leads to the ionization of the outer electron. While periodically driven atomic hydrogen can be seen as a paradigm of quantum chaotic motion in an open (decaying) quantum system, the presence of the non-hydrogenic atomic core - which unavoidably has to be treated quantum mechanically - entails some complications. Indeed, laboratory experiments show clear differences in the ionization dynamics of microwave driven hydrogen and non-hydrogenic Rydberg states. In the first part of this thesis, a machinery is developed that allows for numerical experiments on alkali and hydrogen atoms under precisely identical laboratory conditions. Due to the high density of states in the parameter regime typically explored in laboratory experiments, such simulations are only possible with the most advanced parallel computing facilities, in combination with an efficient parallel implementation of the numerical approach. The second part of the thesis is devoted to the results of the numerical experiment. We identify and describe significant differences and surprising similarities in the ionization dynamics of atomic hydrogen as compared to alkali atoms, and give account of the relevant frequency scales that distinguish hydrogenic from non-hydrogenic ionization behavior. Our results necessitate a reinterpretation of the experimental results so far available, and solve the puzzle of a distinct ionization behavior of periodically driven hydrogen and non-hydrogenic Rydberg atoms - an unresolved question for about one decade. Finally, microwave-driven Rydberg states will be considered as prototypes of open, complex quantum systems that exhibit a complicated temporal decay

Electric Dipole Echoes in Rydberg Atoms

International Nuclear Information System (INIS)

Yoshida, S.; Reinhold, C. O.; Burgdoerfer, J.; Zhao, W.; Mestayer, J. J.; Lancaster, J. C.; Dunning, F. B.

2007-01-01

We report the first observation of echoes in the electric dipole moment of an ensemble of Rydberg atoms precessing in an external electric field F. Rapid reversal of the field direction is shown to play a role similar to that of a π pulse in NMR in rephasing a dephased ensemble of electric dipoles resulting in the buildup of an echo. The mechanisms responsible for this are discussed with the aid of classical trajectory Monte Carlo simulations

Neutron Time-Of-Flight (n_TOF) experiment

CERN Multimedia

Brugger, M; Kaeppeler, F K; Jericha, E; Cortes rossell, G P; Riego perez, A; Baccomi, R; Laurent, B G; Griesmayer, E; Leeb, H; Dressler, M; Cano ott, D; Variale, V; Ventura, A; Carrillo de albornoz trillo, A; Andrzejewski, J J; Pavlik, A F; Kadi, Y; Zanni vlastou, R; Krticka, M; Kokkoris, M; Praena rodriguez, A J; Cortes giraldo, M A; Perkowski, J; Losito, R; Audouin, L; Weiss, C; Tagliente, G; Wallner, A; Woods, P J; Mengoni, A; Guerrero sanchez, C G; Tain enriquez, J L; Vlachoudis, V; Calviani, M; Junghans, A R; Reifarth, R; Mendoza cembranos, E; Quesada molina, J M; Babiano suarez, V; Schumann, M D; Tsinganis, A; Rauscher, T; Calvino tavares, F; Mingrone, F; Gonzalez romero, E M; Colonna, N; Negret, A L; Chiaveri, E; Milazzo, P M; De almeida carrapico, C A; Castelluccio, D M

The neutron time-of-flight facility n_TOF at CERN, Switzerland, operational since 2001, delivers neutrons using the Proton Synchrotron (PS) 20 GeV/c proton beam impinging on a lead spallation target. The facility combines a very high instantaneous neutron flux, an excellent time of flight resolution due to the distance between the experimental area and the production target (185 meters), a low intrinsic background and a wide range of neutron energies, from thermal to GeV neutrons. These characteristics provide a unique possibility to perform neutron-induced capture and fission cross-section measurements for applications in nuclear astrophysics and in nuclear reactor technology.

Properties of Ni^+ from microwave spectroscopy of n=9 Rydberg levels of Nickel

Science.gov (United States)

Woods, Shannon; Keele, Julie; Smith, Chris; Lundeen, Stephen

2012-06-01

The microwave/RESIS method was used to determine the relative positions of 15 of the n=9 Rydberg levels of Nickel with L >= 6. Because the ground state of the Ni^+ ion is a ^2D5/2 level, each Rydberg level (n,L) splits into six eigenstates whose relative positions are determined by long-range e-Ni^+ interactions present in addition to the dominant Coulomb interaction. A previous study with the optical RESIS method determined these positions with precision of +/- 30 MHz [1]. Using the microwave/RESIS method improves that precision by a factor of 300, and leads to much improved determinations of the Ni+ properties that control the long-range interactions. [4pt] [1] Julie A. Keele, Shannon L. Woods, M.E. Hanni, and S.R. Lundeen Phys. Rev. 81, 022506 (2010)

Combined theoretical and experimental study of the valence, Rydberg and ionic states of fluorobenzene

Energy Technology Data Exchange (ETDEWEB)

Palmer, Michael H., E-mail: m.h.palmer@ed.ac.uk; Ridley, Trevor [School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, Scotland EH9 3FJ (United Kingdom); Vrønning Hoffmann, Søren, E-mail: vronning@phys.au.dk, E-mail: nykj@phys.au.dk, E-mail: marcello.coreno@elettra.eu, E-mail: desimone@iom.cnr.it, E-mail: Teng.Zhang@physics.uu.se, E-mail: biczysko@shu.edu.cn, E-mail: alberto.baiardi@sns.it, E-mail: kipeters@wsu.edu; Jones, Nykola C., E-mail: vronning@phys.au.dk, E-mail: nykj@phys.au.dk, E-mail: marcello.coreno@elettra.eu, E-mail: desimone@iom.cnr.it, E-mail: Teng.Zhang@physics.uu.se, E-mail: biczysko@shu.edu.cn, E-mail: alberto.baiardi@sns.it, E-mail: kipeters@wsu.edu [ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Coreno, Marcello, E-mail: vronning@phys.au.dk, E-mail: nykj@phys.au.dk, E-mail: marcello.coreno@elettra.eu, E-mail: desimone@iom.cnr.it, E-mail: Teng.Zhang@physics.uu.se, E-mail: biczysko@shu.edu.cn, E-mail: alberto.baiardi@sns.it, E-mail: kipeters@wsu.edu [CNR-ISM, Basovizza Area Science Park, 1-34149 Trieste (Italy); De Simone, Monica, E-mail: vronning@phys.au.dk, E-mail: nykj@phys.au.dk, E-mail: marcello.coreno@elettra.eu, E-mail: desimone@iom.cnr.it, E-mail: Teng.Zhang@physics.uu.se, E-mail: biczysko@shu.edu.cn, E-mail: alberto.baiardi@sns.it, E-mail: kipeters@wsu.edu [CNR-IOM Laboratorio TASC, Trieste (Italy); Grazioli, Cesare [CNR-IOM Laboratorio TASC, Trieste (Italy); Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste (Italy); Zhang, Teng, E-mail: vronning@phys.au.dk, E-mail: nykj@phys.au.dk, E-mail: marcello.coreno@elettra.eu, E-mail: desimone@iom.cnr.it, E-mail: Teng.Zhang@physics.uu.se, E-mail: biczysko@shu.edu.cn, E-mail: alberto.baiardi@sns.it, E-mail: kipeters@wsu.edu [Department of Physics and Astronomy, University of Uppsala, Uppsala (Sweden); and others

2016-05-28

New photoelectron spectra (PES) and ultra violet (UV) and vacuum UV (VUV) absorption spectra of fluorobenzene recorded at higher resolution than previously, have been combined with mass-resolved (2 + 1) and (3 + 1) resonance enhanced multiphoton ionization (REMPI) spectra; this has led to the identification of numerous Rydberg states. The PES have been compared with earlier mass-analyzed threshold ionization and photoinduced Rydberg ionization (PIRI) spectra to give an overall picture of the ionic state sequence. The analysis of these spectra using both equations of motion with coupled cluster singles and doubles (EOM-CCSD) configuration interaction and time dependent density functional theory (TDDFT) calculations have been combined with vibrational analysis of both the hot and cold bands of the spectra, in considerable detail. The results extend several earlier studies on the vibronic coupling leading to conical intersections between the X{sup 2}B{sub 1} and A{sup 2}A{sub 2} states, and a further trio (B, C, and D) of states. The conical intersection of the X and A states has been explicitly identified, and its structure and energetics evaluated. The energy sequence of the last group is only acceptable to the present study if given as B{sup 2}B{sub 2}of the B and C states forces reconsideration of the nature of the PIRI spectrum. The coupling between these two states is induced by the a{sub 2} modes, ν{sub 12} and ν{sub 14} and we propose that the 14{sup 1} band is observed in the B{sup 2}B{sub 2} band in the PES for the first time, because of the improved resolution. This same assignment is given to the lowest energy band in the PIRI spectrum which was previously assigned as the origin band and further conclude that the entire PIRI spectrum is induced by ν{sub 12} and ν{sub 14}. The relative intensities of

Energy redistribution in the dissociation of low Rydberg states of HeH and 02

International Nuclear Information System (INIS)

Zande, W.J.A. van der.

1988-01-01

In this thesis the dissocation process is studied of the diatomic molecules, heliumhydride and molecular oxygen. In ch.'s 2-4 results on the spectroscopy and dissociative decay of the excited states of heliumhydride (HeH) are explained. The positions and dissociation pathways of the A 2 Σ + and B 2 Π states are determined and a theoretical description of the decay of these states are given. An isotope dependent dissociation behaviour of the C 2 /σ + Rydberg state is reported which explained with this theory. In ch.'s 5-7 observations are presented regarding the first Rydberg states of molecular oxygen. The spectroscopy of the (3sσ)d 1 Π g and C 3 Π g states is treated, and the stability and decay of these Rydberg states is discussed qualitatively. An experimental study is described of the (3sσ)d 1 Π g , v=4-8 states. By isotope studies and resolving rotational lines and the measurements of natural linewidths quantitative estimates have been acquired on coupling strengths, positions of repulsive valence states and perturbations reported in literature from REMPI experiments. The electronic coupling strengths between the C 3 Π g state and the 3 Π g valence state has been established. Observed spin-orbit interactions have been quantified and the dissociation of the multiplet states (C 3 Π g , ω=0-2 has been correlated with the multiplet states of the fragment O 3 P J=0-2 . The spectroscopy of the (3sσ3) Rydberg states which con- verge to and are formed in collisions with the O + 2 , a 4 Π μ ion state, is treated. The (3sσ) 5 /π μ state competition between auto-ionizations and (pre-)dissociation has been observed. 207 refs.; 36 figs.; 18 tabs

TORCH—a Cherenkov based time-of-flight detector

Energy Technology Data Exchange (ETDEWEB)

Dijk, M.W.U. van, E-mail: m.vandijk@bristol.ac.uk [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Brook, N.H. [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Castillo García, L. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland); Laboratory for High Energy Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Cowie, E.N.; Cussans, D. [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); D' Ambrosio, C. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland); Fopma, J. [Denys Wilkinson Laboratory, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Forty, R.; Frei, C. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland); Gao, R. [Denys Wilkinson Laboratory, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Gys, T. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland); Harnew, N.; Keri, T. [Denys Wilkinson Laboratory, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Piedigrossi, D. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland)

2014-12-01

TORCH is an innovative high-precision time-of-flight system to provide particle identification in the difficult intermediate momentum region up to 10 GeV/c. It is also suitable for large-area applications. The detector provides a time-of-flight measurement from the imaging of Cherenkov photons emitted in a 1 cm thick quartz radiator. The photons propagate by total internal reflection to the edge of the quartz plate and are then focused onto an array of photon detectors at the periphery. A time-of-flight resolution of about 10–15 ps per incident charged particle needs to be achieved to allow a three sigma kaon-pion separation up to 10 GeV/c momentum for the TORCH located 9.5 m from the interaction point. Given ∼30 detected photons per incident charged particle, this requires measuring the time-of-arrival of individual photons to about 70 ps. This paper will describe the design of a TORCH prototype involving a number of ground-breaking and challenging techniques.

State-to-state dynamics of the H*(n) + HD → D*(n′) + H2 reactive scattering

International Nuclear Information System (INIS)

Yu, Shengrui; Su, Shu; Dai, Dongxu; Yuan, Kaijun; Yang, Xueming

2014-01-01

The state-to-state dynamics of the H * (n) + HD → D * (n ′ ) + H 2 reactive scattering at the collision energy of 0.5 eV have been carried out for the first time by using H-atom Rydberg tagging time-of-flight technique. Experimental results show that the angular distribution of the total H 2 products presents clearly forward-backward asymmetric, which considerably differs from that of the corresponding H + + HD → D + + H 2 reaction predicted by previously theoretical calculations. Such disagreement between these two processes suggests that the Fermi independent-collider model is also not valid in describing the dynamics of isotopic variants of the H * + H 2 reaction. The rotational state distribution of the H 2 products demonstrates a saw-toothed distribution with odd-j ′ > even-j ′ . This interesting observation is strongly influenced by nuclear spin statistics

Systematic observation of tunneling field-ionization in highly excited Rb Rydberg atoms

International Nuclear Information System (INIS)

Kishimoto, Y.; Tada, M.; Kominato, K.; Shibata, M.; Yamada, S.; Haseyama, T.; Ogawa, I.; Funahashi, H.; Yamamoto, K.; Matsuki, S.

2002-01-01

Pulsed field ionization of high-n (90≤n≤150) manifold states in Rb Rydberg atoms has been investigated in high slew-rate regime. Two peaks in the field ionization spectra were systematically observed for the investigated n region, where the field values at the lower peak do not almost depend on the excitation energy in the manifold, while those at the higher peak increase with increasing excitation energy. The fraction of the higher peak component to the total ionization signals increases with increasing n, exceeding 80% at n=147. Characteristic behavior of the peak component and the comparison with theoretical predictions indicate that the higher peak component is due to the tunneling process. The obtained results show that the tunneling process plays increasingly the dominant role at such highly excited nonhydrogenic Rydberg atoms

Ion microtomography using ion time-of-flight

International Nuclear Information System (INIS)

Roberts, M.L.; Heikkinen, D.W.; Proctor, I.D.; Pontau, A.E.; Olona, G.T.; Felter, T.E.; Morse, D.H.; Hess, B.V.

1992-01-01

We have developed and are in the process of testing an ion time-of-flight (TOF) detector system for use in our ion microtomography measurements. Using TOF, ion energy is determined by measurement of the ion's flight time over a certain path length. For ion microtomography, the principle advantage of TOF analysis is that ion count rates of several hundred thousand counts per second can be achieved as compared to a limit of about ten thousand ions per second when using a solid-state silicon surface barrier detector and associated electronics. This greater than 10 fold increase in count rate correspondingly shortens sample analysis time or increases the amount of data that can be collected on a given sample. Details of the system and progress to date are described

The use of external electronic tags on fish: an evaluation of tag retention and tagging effects

DEFF Research Database (Denmark)

Jepsen, Niels; Thorstad, Eva B.; Havn, Torgeir

2015-01-01

External tagging of fish with electronic tags has been used for decades for a wide range of marine and freshwater species. In the early years of fish telemetry research, it was the most commonly used attachment method, but later internal implants became preferred. Recently, the number of telemetry...... unsuitable for surgical implantation, or when using tags with sensors recording the external environment. The most commonly reported problems with external tags are tissue damage, premature tag loss, and decreased swimming capacity, but the effects are highly context dependent and species specific. Reduced......, but particularly there are few studies on predation risk, social interactions, and studies distinguishing capture and handling effects from tagging effects. For PSATs, especially those that are large relative to fish size, there are particular problems with a high proportion of premature tag losses, reduced...

Tempting To Tag: An Experimental Comparison Of Four Tagging Input Mechanisms

Directory of Open Access Journals (Sweden)

Mark Melenhorst

2010-01-01

Full Text Available Tagging helps achieve improved indexing and recommendation of resources (e.g., videos or pictures in large data collections. In order to reap the benefits of tagging, people must be persuaded to label the resources they consume. This paper reports on a study in which four different tagging input mechanisms and their effect on users' motivation to tag were compared. The mechanisms consisted of a standard tag input box, a chatbot-like environment, a bookmarking mechanism, and a "tag and vote" game. The results of our experiment show that the use of the nonstandard tagging input mechanisms does not affect users' motivation to tag. In some instances tagging mechanisms were found to distract users from their primary task: consuming resources. Persuading people to tag might be accomplished more effectively by using other motivating tagging mechanisms (e.g., tagging games, or motivation could be created by explaining the usefulness of tagging.

The role of high Rydberg states in the generation of negative ions in negative-ion discharges

International Nuclear Information System (INIS)

Hiskes, J.R.

1995-01-01

The generation of substantial yields of H - ions in a laser excited H 2 gas has been reported by Pinnaduwage and Christoforu. These H - yields have been attributed to (2 + 1) REMP photoexcitation processes leading to dissociative attachment of doubly-excited or superexcited states (SES), or dissociative attachment of high Rydberg product states. The new feature of these experiments is the implied large dissociative attachment rates, of order 10 -6 cm 3 sec -1 , values that are orders-of-magnitude larger than the dissociative attachment of the vibrationally excited levels of the ground electronic state. While these laser excitations are not directly applicable to a hydrogen negative-ion discharge, the implication of large dissociative attachment rates to the high Rydberg states may affect both the total negative-ion density and the interpretation of discharge performance. Within the discharge energetic electrons will collisionally excite the higher Rydberg states, and the relative contribution of the dissociative attachment of these states when compared with the dissociative attachment to the ground state vibrational levels, is the topic of this paper

Time-of-flight detector with KBr working medium

International Nuclear Information System (INIS)

Arvanov, A.N.; Gavalyan, V.G.; Lorikyan, M.P.

1983-01-01

A detector of controlled secondary electron emission as a 3-electrode focusing electrostatic system of the photomultiplier input chamber having a microchannel electron plate herringbone assembly with the total gain of approXimately 10 7 is described. A controlled secondary emission emitter based on MgO or KBr is installed as a cathode. The detector is designed for time-of-flight spectrometers. The time resolution is < or approximately equal to 0.5 ns. The time-of-flight system realized on the base of such two detectors has 100% detection efficiency and it is ''transparent'' for an identified particle. Its characteristics for α particle, deuteron and proton detection are estimated

From the Rydberg constant to the fundamental constants metrology

International Nuclear Information System (INIS)

Nez, F.

2005-06-01

This document reviews the theoretical and experimental achievements of the author since the beginning of his scientific career. This document is dedicated to the spectroscopy of hydrogen, deuterium and helium atoms. The first part is divided into 6 sub-sections: 1) the principles of hydrogen spectroscopy, 2) the measurement of the 2S-nS/nD transitions, 3) other optical frequency measurements, 4) our contribution to the determination of the Rydberg constant, 5) our current experiment on the 1S-3S transition, 6) the spectroscopy of the muonic hydrogen. Our experiments have improved the accuracy of the Rydberg Constant by a factor 25 in 15 years and we have achieved the first absolute optical frequency measurement of a transition in hydrogen. The second part is dedicated to the measurement of the fine structure constant and the last part deals with helium spectroscopy and the search for optical references in the near infrared range. (A.C.)

Auto transfer to Rydberg states during ion-atom collisions

International Nuclear Information System (INIS)

Bachau, H.; Harel, C.; Barat, M.; Roncin, P.; Bordenave-Montesquieu, A.; Moretto-Capelle, P.; Benoit-Cattin, P.; Gleizes, A.; Benhenni, M.

1993-01-01

Electron capture by slow multiply charged ions colliding on rare-gas targets is known to populate highly excited states of the projectile. On the basis of experimental measurement of energy and angle differential cross-sections we have shown that capture to a resonant doubly excited state may lead to Autoionizing Double Capture (ADC) as well as to True Double Capture (TDC). In this model TDC appears as a two step post-collisional process, the state populated by the collision decays to (or delutes into) a dense adjacent Rydberg series, followed by radiative deexcitation of the inner electron of the (3,n) Rydberg states. We report here new experimental observations in electron spectra measured in N 7+ +He. Auto transfer to Rydber states has also important consequences on the determination of the lifetime of the autoionizing states, some discrepancies between theoretical width values for low N 5+ (4,4) resonant states will be discussed and partially resolved

Auto transfer to Rydberg states during ion-atom collisions

Energy Technology Data Exchange (ETDEWEB)

Bachau, H.; Harel, C. (Laboratoire des Collisions Atomiques, Unite Propre de Recherche 260 du CNRS, Universite Bordeaux I, 351 Cours de la Liberation, 33405 Talence (France)); Barat, M.; Roncin, P. (Laboratoire des Collisions Atomiques et Moleculaires, Unite associee 281 du CNRS, Universite de Paris Sud, Batiment 351, 91405 Orsay (France)); Bordenave-Montesquieu, A.; Moretto-Capelle, P.; Benoit-Cattin, P.; Gleizes, A.; Benhenni, M. (IRSAMC, Unite associee 770 du CNRS, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse (France))

1993-06-05

Electron capture by slow multiply charged ions colliding on rare-gas targets is known to populate highly excited states of the projectile. On the basis of experimental measurement of energy and angle differential cross-sections we have shown that capture to a resonant doubly excited state may lead to Autoionizing Double Capture (ADC) as well as to True Double Capture (TDC). In this model TDC appears as a two step post-collisional process, the state populated by the collision decays to (or delutes into) a dense adjacent Rydberg series, followed by radiative deexcitation of the inner electron of the (3,n) Rydberg states. We report here new experimental observations in electron spectra measured in [ital N][sup 7+]+[ital He]. Auto transfer to Rydber states has also important consequences on the determination of the lifetime of the autoionizing states, some discrepancies between theoretical width values for low [ital N][sup 5+](4,4) resonant states will be discussed and partially resolved.

Assessing and minimizing contamination in time of flight based validation data

Science.gov (United States)

Lennox, Kristin P.; Rosenfield, Paul; Blair, Brenton; Kaplan, Alan; Ruz, Jaime; Glenn, Andrew; Wurtz, Ronald

2017-10-01

Time of flight experiments are the gold standard method for generating labeled training and testing data for the neutron/gamma pulse shape discrimination problem. As the popularity of supervised classification methods increases in this field, there will also be increasing reliance on time of flight data for algorithm development and evaluation. However, time of flight experiments are subject to various sources of contamination that lead to neutron and gamma pulses being mislabeled. Such labeling errors have a detrimental effect on classification algorithm training and testing, and should therefore be minimized. This paper presents a method for identifying minimally contaminated data sets from time of flight experiments and estimating the residual contamination rate. This method leverages statistical models describing neutron and gamma travel time distributions and is easily implemented using existing statistical software. The method produces a set of optimal intervals that balance the trade-off between interval size and nuisance particle contamination, and its use is demonstrated on a time of flight data set for Cf-252. The particular properties of the optimal intervals for the demonstration data are explored in detail.

Accurate Mapping of Multilevel Rydberg Atoms on Interacting Spin-1 /2 Particles for the Quantum Simulation of Ising Models

Science.gov (United States)

de Léséleuc, Sylvain; Weber, Sebastian; Lienhard, Vincent; Barredo, Daniel; Büchler, Hans Peter; Lahaye, Thierry; Browaeys, Antoine

2018-03-01

We study a system of atoms that are laser driven to n D3 /2 Rydberg states and assess how accurately they can be mapped onto spin-1 /2 particles for the quantum simulation of anisotropic Ising magnets. Using nonperturbative calculations of the pair potentials between two atoms in the presence of electric and magnetic fields, we emphasize the importance of a careful selection of experimental parameters in order to maintain the Rydberg blockade and avoid excitation of unwanted Rydberg states. We benchmark these theoretical observations against experiments using two atoms. Finally, we show that in these conditions, the experimental dynamics observed after a quench is in good agreement with numerical simulations of spin-1 /2 Ising models in systems with up to 49 spins, for which numerical simulations become intractable.

The ANTARES recoil time-of-flight spectrometer

Energy Technology Data Exchange (ETDEWEB)

Martin, J.W.; Russell, G.J. [New South Wales Univ., Kensington, NSW (Australia); Cohen, D.D.; Dytlewski, N. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

1996-12-31

The Australian National Tandem for Applied Research (ANTARES), is a 8MV FN tandem particle accelerator at the Australian Nuclear Science and Technology Organisation. Research on the accelerator is divided between two groups, Accelerator Mass Spectrometry (AMS) and lon Beam Analysis (IBA). The IBA group carries out a range of research projects from nuclear physics to materials characterisation. The major IBA project on the accelerator is a recoil time-of-flight spectrometer which consists of two electrostatic time pulse generators and an ion-implanted surface barrier detector. The spectrometer is ideally suited to the profiling of layered multi-element materials, and has been used to characterise materials such as metal-germanides, optoelectronics, superconductors and catalytic converters. This paper will describe the time-of-flight system as well as some recent materials characterisation results. 1 refs., 3 figs.

The ANTARES recoil time-of-flight spectrometer

Energy Technology Data Exchange (ETDEWEB)

Martin, J W; Russell, G J [New South Wales Univ., Kensington, NSW (Australia); Cohen, D D; Dytlewski, N [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

1997-12-31

The Australian National Tandem for Applied Research (ANTARES), is a 8MV FN tandem particle accelerator at the Australian Nuclear Science and Technology Organisation. Research on the accelerator is divided between two groups, Accelerator Mass Spectrometry (AMS) and lon Beam Analysis (IBA). The IBA group carries out a range of research projects from nuclear physics to materials characterisation. The major IBA project on the accelerator is a recoil time-of-flight spectrometer which consists of two electrostatic time pulse generators and an ion-implanted surface barrier detector. The spectrometer is ideally suited to the profiling of layered multi-element materials, and has been used to characterise materials such as metal-germanides, optoelectronics, superconductors and catalytic converters. This paper will describe the time-of-flight system as well as some recent materials characterisation results. 1 refs., 3 figs.

The electro-mechanical integration of the NA62 GigaTracker time tagging pixel detector

CERN Document Server

Morel, M; Aglieri Rinella, G; Carassiti, V; Ceccucci, A; Daguin, J; Fiorini, M; Jarron, P; Kaplon, J; Mapelli, A; Marchetto, F; Noy, M; Nuessle, G; Perktold, L; Petagna, P; Riedler, P

2010-01-01

The NA62 GigaTracker is a low mass time tagging hybrid pixel detector operating in a beam with a particle rate of 750 MHz. It consists of three stations with a sensor size of 60 × 27mm2 containing 18000 pixels, each 300 × 300μm2. The active area is connected to a matrix of 2 × 5 pixel ASICs, which time tag the arrival of the particles with a binning of 100 ps. The detector operates in vacuum at -20 to 0°C and the material budget per station must be below 0.5% X0. Due to the high radiation environment of 2 × 1014 1 MeV neutron equivalent cm−2/yr−1 it is planned to exchange the detector modules regularly. The low material budget, cooling requirements and the request for easy module access has driven the electro-mechanical integration of the GigaTracker, which is presented in this paper

Seasonal and circadian biases in bird tracking with solar GPS-tags.

Directory of Open Access Journals (Sweden)

Rafa Silva

Full Text Available Global Positioning System (GPS tags are nowadays widely used in wildlife tracking. This geolocation technique can suffer from fix loss biases due to poor satellite GPS geometry, that result in tracking data gaps leading to wrong research conclusions. In addition, new solar-powered GPS tags deployed on birds can suffer from a new "battery drain bias" currently ignored in movement ecology analyses. We use a GPS tracking dataset of bearded vultures (Gypaetus barbatus, tracked for several years with solar GPS tags, to evaluate the causes and triggers of fix and data retrieval loss biases. We compare two models of solar GPS tags using different data retrieval systems (Argos vs GSM-GPRS, and programmed with different duty cycles. Neither of the models was able to accomplish the duty cycle programed initially. Fix and data retrieval loss rates were always greater than expected, and showed non-random gaps in GPS locations. Number of fixes per month of tracking was a bad criterion to identify tags with smaller biases. Fix-loss rates were four times higher due to battery drain than due to poor GPS satellite geometry. Both tag models were biased due to the uneven solar energy available for the recharge of the tag throughout the annual cycle, resulting in greater fix-loss rates in winter compared to summer. In addition, we suggest that the bias found along the diurnal cycle is linked to a complex three-factor interaction of bird flight behavior, topography and fix interval. More fixes were lost when vultures were perching compared to flying, in rugged versus flat topography. But long fix-intervals caused greater loss of fixes in dynamic (flying versus static situations (perching. To conclude, we emphasize the importance of evaluating fix-loss bias in current tracking projects, and deploying GPS tags that allow remote duty cycle updates so that the most appropriate fix and data retrieval intervals can be selected.

Cavity quantum electrodynamics with a Rydberg-blocked atomic ensemble

DEFF Research Database (Denmark)

Guerlin, Christine; Brion, Etienne; Esslinger, Tilman

2010-01-01

The realization of a Jaynes-Cummings model in the optical domain is proposed for an atomic ensemble. The scheme exploits the collective coupling of the atoms to a quantized cavity mode and the nonlinearity introduced by coupling to high-lying Rydberg states. A two-photon transition resonantly cou...

Time-of-flight scattering and recoiling spectrometry

International Nuclear Information System (INIS)

Rabalais, J.W.

1991-01-01

Ion scattering and recoiling spectrometry consists of directing a collimated beam of monoenergetic ions towards a surface and measuring the flux of scattered and recoiled particles from this surface. When the neutral plus ion flux is velocity selected by measuring the flight times from the sample to the detector, the technique is called time-of-flight scattering and recoiling spectrometry (TOF-SARS). TOF-SARS is capable of (1) surface elemental analysis by applying classical mechanics to the velocities of the particles, (2) surface structural analysis by monitoring the angular anisotropies in the particle flux, and (3) ion-surface electron exchange probabilities by analysis of the ion/neutral fractions in the particle flux. Examples of these three areas are presented herein

Effects of confinement on the Rydberg molecule NeH

International Nuclear Information System (INIS)

Lo, J M H; Klobukowski, M; Bielinska-Waz, D; Diercksen, G H F; Schreiner, E W S

2005-01-01

Ab initio potential energy curves of the Rydberg NeH molecule in the presence of cylindrical spatial confinement were computed by the method of multi-reference configuration interaction with extended basis sets. The influence of the applied potential to the structures and spectra of the ground and excited states of NeH was analysed in terms of perturbation theory. In addition, the phenomenon of field-induced ionization was discussed

Cosmic radiation algorithm utilizing flight time tables

International Nuclear Information System (INIS)

Katja Kojo, M.Sc.; Mika Helminen, M.Sc.; Anssi Auvinen, M.D.Ph.D.; Katja Kojo, M.Sc.; Anssi Auvinen, M.D.Ph.D.; Gerhard Leuthold, D.Sc.

2006-01-01

Cosmic radiation is considerably higher on cruising altitudes used in aviation than at ground level. Exposure to cosmic radiation may increase cancer risk among pilots and cabin crew. The International Commission on Radiation Protection (ICRP) has recommended that air crew should be classified as radiation workers. Quantification of cosmic radiation doses is necessary for assessment of potential health effects of such occupational exposure. For Finnair cabin crew (cabin attendants and stewards), flight history is not available for years prior to 1991 and therefore, other sources of information on number and type of flights have to be used. The lack of systematically recorded information is a problem for dose estimation for many other flight companies personnel as well. Several cosmic radiation dose estimations for cabin crew have been performed using different methods (e.g. 2-5), but they have suffered from various shortcomings. Retrospective exposure estimation is not possible with personal portable dosimeters. Methods that employ survey data for occupational dose assessment are prone to non-differential measurement error i.e. the cabin attendants do not remember correctly the number of past flights. Assessment procedures that utilize surrogate measurement methods i.e. the duration of employment, lack precision. The aim of the present study was to develop an assessment method for individual occupational exposure to cosmic radiation based on flight time tables. Our method provides an assessment method that does not require survey data or systematic recording of flight history, and it is rather quick, inexpensive, and possible to carry out in all other flight companies whose past time tables for the past periods exist. Dose assessment methods that employ survey data are prone to random error i.e. the cabin attendants do not remember correctly the number or types of routes that they have flown during the past. Our method avoids this since survey data are not needed

Comparison of detector materials for time-of-flight positron tomography

International Nuclear Information System (INIS)

Derenzo, S.E.

1982-06-01

Knowledge of detection efficiency and timing resolution is essential when comparing detector materials for time-of-flight positron tomography. We present results of Monte Carlo calculations of the detection efficiency of plastic, lead loaded plastic, NaI(T1), liquid xenon, bismuth germanate (BGO), CsF, BaF 2 , Ge, and HgI 2 for 511 keV photons. We also use recently published values of timing resolution for these detector materials to tabulate the quantity (efficiency) 2 /(time resolution) which is a measure of the relative sensitivity for time of flight positron tomography

Real-time flavor tagging selection in ATLAS

CERN Document Server

Sahinsoy, M; The ATLAS collaboration

2014-01-01

In high-energy physics experiments, online selection is crucial to reject most uninteresting collisions; in particular, b-jet selections, part of the ATLAS trigger strategy, are meant to select final states with heavy-flavor content. This is the only option to select fully hadronic final states containing b-jets, and is important to reject QCD light jets and maintain affordable trigger rates without raising jet energy thresholds. ATLAS operated b-jet triggers in both 2011 and 2012 data-taking campaigns and is now working to improve the performance of tagging algorithms for Run2. An overview of the ATLAS b-jet trigger strategy and its performance on real data is presented in this contribution, along with future prospects. Data-driven techniques to extract the online b-tagging performance, a key ingredient for all analyses relying on such triggers, are also discussed and results presented.

Time-of-flight position-sensitive x-ray detection

International Nuclear Information System (INIS)

Mowat, J.W.

1981-01-01

A new method for recording beam-foil time-of-flight data is described. A stationary, side-window, position-senstive proportional counter, oriented with anode wire parallel to the ion beam, views the decay in flight of excited ions through a Soller slit x-ray collimator. In contrast to the standard method, the exciter foil, placed within or upstream from the field of view, is not moved during the acquisition of a decay curve. Each point on the anode acts like an independent detector seeing a unique segment of the ion beam. The correspondence between the downstream distance at which an ion decays and the position along the anode at which the x-ray is detected makes a pulse-height spectrum of position pulses equivalent to a time-of-flight decay curve. Thus an entire decay curve can now be acquired without moving the foil. Increased efficiency is the most significant improvement over the standard method in which the radiation detector views only a small segment of the flight path at any one time. Experiments using translating foils are subject to a spurious dependence of x-ray intensity on foil position if the foil is non-uniform (or non-uniformly aged) and wobbles as it moves. This effect is eliminated here. Foil aging effects which influence excitation rates and introduce a slowly varying time dependence of the x-ray intensity are automatically normalized by this multichannel technique. The application of this method to metastable x-ray emitting states of low-Z ions are discussed

Topological matter with collective encoding and Rydberg blockade

DEFF Research Database (Denmark)

Nielsen, Anne E. B.; Mølmer, Klaus

2010-01-01

We propose to use a permutation symmetric sample of multilevel atoms to simulate the properties of topologically ordered states. The Rydberg blockade interaction is used to prepare states of the sample which are equivalent to resonating valence bond states, Laughlin states, and string-net condens......-net condensates and to create and study the properties of their quasi-particle-like fundamental excitations....

Doppler time-of-flight imaging

KAUST Repository

Heide, Felix

2015-07-30

Over the last few years, depth cameras have become increasingly popular for a range of applications, including human-computer interaction and gaming, augmented reality, machine vision, and medical imaging. Many of the commercially-available devices use the time-of-flight principle, where active illumination is temporally coded and analyzed on the camera to estimate a per-pixel depth map of the scene. In this paper, we propose a fundamentally new imaging modality for all time-of-flight (ToF) cameras: per-pixel velocity measurement. The proposed technique exploits the Doppler effect of objects in motion, which shifts the temporal frequency of the illumination before it reaches the camera. Using carefully coded illumination and modulation frequencies of the ToF camera, object velocities directly map to measured pixel intensities. We show that a slight modification of our imaging system allows for color, depth, and velocity information to be captured simultaneously. Combining the optical flow computed on the RGB frames with the measured metric axial velocity allows us to further estimate the full 3D metric velocity field of the scene. We believe that the proposed technique has applications in many computer graphics and vision problems, for example motion tracking, segmentation, recognition, and motion deblurring.

Entanglement of two ground state neutral atoms using Rydberg blockade

DEFF Research Database (Denmark)

Miroshnychenko, Yevhen; Browaeys, Antoine; Evellin, Charles

2011-01-01

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

Rules for Flight Paths and Time of Flight for Flows in Porous Media with Heterogeneous Permeability and Porosity

Directory of Open Access Journals (Sweden)

Lihua Zuo

2017-01-01

Full Text Available Porous media like hydrocarbon reservoirs may be composed of a wide variety of rocks with different porosity and permeability. Our study shows in algorithms and in synthetic numerical simulations that the flow pattern of any particular porous medium, assuming constant fluid properties and standardized boundary and initial conditions, is not affected by any spatial porosity changes but will vary only according to spatial permeability changes. In contrast, the time of flight along the streamline will be affected by both the permeability and porosity, albeit in opposite directions. A theoretical framework is presented with evidence from flow visualizations. A series of strategically chosen streamline simulations, including systematic spatial variations of porosity and permeability, visualizes the respective effects on the flight path and time of flight. Two practical rules are formulated. Rule  1 states that an increase in permeability decreases the time of flight, whereas an increase in porosity increases the time of flight. Rule  2 states that the permeability uniquely controls the flight path of fluid flow in porous media; local porosity variations do not affect the streamline path. The two rules are essential for understanding fluid transport mechanisms, and their rigorous validation therefore is merited.

The Closed-Orbit Theory for General Rydberg Atoms in External Fields

International Nuclear Information System (INIS)

Carboni, R.

1997-01-01

The photoabsorption spectra of hydrogen Rydberg atoms, as well of model Rydberg atoms in pure magnetic or electric fields have been successfully calculated using the semiclassical closed-orbit theory. The theory relates the resonances of the spectra to closed classical orbits of the excited electron. The dynamics of multielectron atoms is more complicated than the hydrogenic one; additionally, when the atoms are in the presence of perpendicular magnetic and electric fields becomes more complex than when they are in pure fields, due to the fact that the Hamiltonian is non-separable in three degrees of freedom, instead of two non-separable degrees of freedom. In this work, I present an extension of the closed-orbit theory to three degrees of freedom, considering arbitrary quantum defects, i.e., general atoms. (Author) [es

SHMS Hodoscopes and Time of Flight System

Science.gov (United States)

Craycraft, Kayla; Malace, Simona

2017-09-01

As part of the Thomas Jefferson National Accelerator Facility's (Jefferson Lab) upgrade from 6 GeV to 12 GeV, a new magnetic focusing spectrometer, the Super High Momentum Spectrometer (SHMS), was installed in experimental Hall C. The detector stack consists of horizontal drift chambers for tracking, gas Cerenkov and Aerogel detectors and a lead glass calorimeter for particle identification. A hodoscope system consisting of three planes of scintillator detectors (constructed by James Madison University) and one plane of quartz bars (built by North Carolina A&T State University) is used for triggering and time of flight measurements. This presentation consists of discussion of the installation, calibration, and characterization of the detectors used in this Time of Flight system. James Madison University, North Carolina A&T State University.

Quasi-free scattering in the ionization and destruction of hydrogen and helium Rydberg atoms in collision with neutral targets

International Nuclear Information System (INIS)

Renwick, S.P.

1992-01-01

Hydrogen and helium Rydberg atoms (H** and He**), with principal quantum number n ranging from 10 to 20, have been used in collision experiments from 1 to 40 keV/amu. These were produced by electron capture in a charge-exchange cell and analyzed by ionization in a modulated electric field combined with phase-sensitive detection. Three experiments have been conducted. In the first, spectra of the band of H and He Rydberg states from electron capture were produced by the modulated field technique and compared. Considerable differences were found between the two. Both types of spectra were analyzed with calculations of Stark energies and field ionization rates. Attempts were made to simulate the spectra using this information and some assumptions about the state distribution produced in the electron capture. In the second experiment, destruction cross sections for H** incident on N 2 , Ar, and SF 6 were measured. This was a further test of the independent-particle model for Rydberg atom scattering; in this model, the atom is destroyed by quasi-free scattering of either the ionic core or the outer electron. Already proven valid for n = 20-35, this has been extended to n as low as 10, as measurements with n = 10 showed full compliance with the model. In the third experiment, not only destruction cross sections but also ionization cross sections for H** and He** incident on Xe, AR, and N 2 were measured. The ionization measurement is a more sensitive test of the quasi-free scattering of the Rydberg electron. This was especially important for the Xe and Ar targets, which exhibits a Ramsauer-Townsend minimum in their free-electron scattering cross sections. The quasi-free Rydberg electron should reproduce these data. Unmistakable deviations from the quasi-free prediction were seen in Xe and N 2 but not in Ar. This represents the first measurement of a breakdown of the Independent Particle Model for fast Rydberg atom scattering

Real-time flavor tagging selection in ATLAS

CERN Document Server

Madaffari, D; The ATLAS collaboration

2014-01-01

In high-energy physics experiments on hadron colliders, online selection is crucial to reject most uninteresting collisions. In particular, the ATLAS experiment includes b-jet selections in its trigger strategy, in order to select final states with heavy-flavor content and enlarge its physics potentials. Dedicated selections are developed to quickly identify fully hadronic final states containing b-jets, while rejecting light QCD jets, and maintain affordable trigger rates without raising jet energy thresholds. ATLAS successfully operated b-jet trigger selections during both 2011 and 2012 data-taking campaigns and hard work is on-going now to improve the performance of tagging algorithms for coming Run2 in 2015. An overview of the ATLAS b-jet trigger strategy and its performance on real data is presented in this contribution, along with future prospects. Data-driven techniques to extract the online b-tagging performance, a key ingredient for all analyses relying on such triggers, are also discussed and result...

Guidance concepts for time-based flight operations

Science.gov (United States)

Vicroy, Dan D.

1990-01-01

Airport congestion and the associated delays are severe in today's airspace system and are expected to increase. NASA and the FAA is investigating various methods of alleviating this problem through new technology and operational procedures. One concept for improving airspace productivity is time-based control of aircraft. Research to date has focused primarily on the development of time-based flight management systems and Air Traffic Control operational procedures. Flight operations may, however, require special onboard guidance in order to satisfy the Air Traffic Control imposed time constraints. The results are presented of a simulation study aimed at evaluating several time-based guidance concepts in terms of tracking performance, pilot workload, and subjective preference. The guidance concepts tested varied in complexity from simple digital time-error feedback to an advanced time-referenced-energy guidance scheme.

Positive-column plasma studied by fast-flow glow discharge mass spectrometry: Could it be a 'Rydberg gas?'

International Nuclear Information System (INIS)

Mason, Rod S.; Miller, Pat D.; Mortimer, Ifor; Mitchell, David J.; Dash, Neil A.

2003-01-01

Ions created from the fast-flowing positive column plasma of a glow discharge were monitored using a high voltage magnetic sector mass spectrometer. Since the field gradient and sheath potentials created by the plasma inside the source opposed cation transfer, it is inferred that the ions detected were the field-ionized Rydberg species. This is supported by the mass spectral changes which occurred when a negative bias was applied to the sampling aperture and by the contrasting behavior when attached to a quadrupole analyzer. Reaction with H 2 (titrated into the flowing plasma) quenched not only the ionization of discharge gas Rydberg atoms but also the passage of electric current through the plasma, without significant changes to the field and sheath potentials. Few 'free' ions were present and the lifetimes of the Rydberg atoms detected were much longer than seen in lower pressure experiments, indicating additional stabilization in the plasma environment. The observations support the model of the flowing plasma, given previously [R. S. Mason, P. D. Miller, and I. P. Mortimer, Phys. Rev. E 55, 7462 (1997)] as mainly a neutral Rydberg atom gas, rather than a conventional ion-electron plasma

A suite of standard post-tagging evaluation metrics can help assess tag retention for field-based fish telemetry research

Science.gov (United States)

Gerber, Kayla M.; Mather, Martha E.; Smith, Joseph M.

2017-01-01

Telemetry can inform many scientific and research questions if a context exists for integrating individual studies into the larger body of literature. Creating cumulative distributions of post-tagging evaluation metrics would allow individual researchers to relate their telemetry data to other studies. Widespread reporting of standard metrics is a precursor to the calculation of benchmarks for these distributions (e.g., mean, SD, 95% CI). Here we illustrate five types of standard post-tagging evaluation metrics using acoustically tagged Blue Catfish (Ictalurus furcatus) released into a Kansas reservoir. These metrics included: (1) percent of tagged fish detected overall, (2) percent of tagged fish detected daily using abacus plot data, (3) average number of (and percent of available) receiver sites visited, (4) date of last movement between receiver sites (and percent of tagged fish moving during that time period), and (5) number (and percent) of fish that egressed through exit gates. These metrics were calculated for one to three time periods: early (of the study (5 months). Over three-quarters of our tagged fish were detected early (85%) and at the end (85%) of the study. Using abacus plot data, all tagged fish (100%) were detected at least one day and 96% were detected for > 5 days early in the study. On average, tagged Blue Catfish visited 9 (50%) and 13 (72%) of 18 within-reservoir receivers early and at the end of the study, respectively. At the end of the study, 73% of all tagged fish were detected moving between receivers. Creating statistical benchmarks for individual metrics can provide useful reference points. In addition, combining multiple metrics can inform ecology and research design. Consequently, individual researchers and the field of telemetry research can benefit from widespread, detailed, and standard reporting of post-tagging detection metrics.

Multivariate Sensitivity Analysis of Time-of-Flight Sensor Fusion

Science.gov (United States)

Schwarz, Sebastian; Sjöström, Mårten; Olsson, Roger

2014-09-01

Obtaining three-dimensional scenery data is an essential task in computer vision, with diverse applications in various areas such as manufacturing and quality control, security and surveillance, or user interaction and entertainment. Dedicated Time-of-Flight sensors can provide detailed scenery depth in real-time and overcome short-comings of traditional stereo analysis. Nonetheless, they do not provide texture information and have limited spatial resolution. Therefore such sensors are typically combined with high resolution video sensors. Time-of-Flight Sensor Fusion is a highly active field of research. Over the recent years, there have been multiple proposals addressing important topics such as texture-guided depth upsampling and depth data denoising. In this article we take a step back and look at the underlying principles of ToF sensor fusion. We derive the ToF sensor fusion error model and evaluate its sensitivity to inaccuracies in camera calibration and depth measurements. In accordance with our findings, we propose certain courses of action to ensure high quality fusion results. With this multivariate sensitivity analysis of the ToF sensor fusion model, we provide an important guideline for designing, calibrating and running a sophisticated Time-of-Flight sensor fusion capture systems.

Studies and comparisons of two photon-tagging systems for the production of monochromatic photon beams for photonuclear experiments

International Nuclear Information System (INIS)

Aniel, Thierry.

1982-06-01

The performance of photon beams obtained by two different tagging processes (tagging of ''hard'' annihilation photons with ''soft'' associated photons, tagging of bremstrahlung photons with associated electrons) on the same facility was studied. The two processes are described and experimental results on the characteristics of the resulting beams given. The respective advantages of both methods are compared with one another and with those of a quasi-monochromatic beam obtained by the in-flight annihilation of a positron beam. A development based on the second process is then studied together with its applications to photonuclear physics [fr

Comparison of fluorescent tags for analysis of mannose-6-phosphate glycans.

Science.gov (United States)

Kang, Ji-Yeon; Kwon, Ohsuk; Gil, Jin Young; Oh, Doo-Byoung

2016-05-15

Mannose-6-phosphate (M-6-P) glycan analysis is important for quality control of therapeutic enzymes for lysosomal storage diseases. Here, we found that the analysis of glycans containing two M-6-Ps was highly affected by the hydrophilicity of the elution solvent used in high-performance liquid chromatography (HPLC). In addition, the performances of three fluorescent tags--2-aminobenzoic acid (2-AA), 2-aminobenzamide (2-AB), and 3-(acetyl-amino)-6-aminoacridine (AA-Ac)--were compared with each other for M-6-P glycan analysis using HPLC and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The best performance for analyzing M-6-P glycans was shown by 2-AA labeling in both analyses. Copyright © 2016 Elsevier Inc. All rights reserved.

A time-focusing Fourier chopper time-of-flight diffractometer for large scattering angles

International Nuclear Information System (INIS)

Heinonen, R.; Hiismaeki, P.; Piirto, A.; Poeyry, H.; Tiitta, A.

1975-01-01

A high-resolution time-of-flight diffractometer utilizing time focusing principles in conjunction with a Fourier chopper is under construction at Otaniemi. The design is an improved version of a test facility which has been used for single-crystal and powder diffraction studies with promising results. A polychromatic neutron beam from a radial beam tube of the FiR 1 reactor, collimated to dia. 70 mm, is modulated by a Fourier chopper (dia. 400 mm) which is placed inside a massive boron-loaded particle board shielding of 900 mm wall thickness. A thin flat sample (5 mm x dia. 80 mm typically) is mounted on a turntable at a distance of 4 m from the chopper, and the diffracted neutrons are counted by a scintillation detector at 4 m distance from the sample. The scattering angle 2theta can be chosen between 90deg and 160deg to cover Bragg angles from 45deg up to 80deg. The angle between the chopper disc and the incident beam direction as well as the angle of the detector surface relative to the diffracted beam can be adjusted between 45deg and 90deg in order to accomplish time-focusing. In our set-up, with equal flight paths from chopper to sample and from sample to detector, the time-focusing conditions are fulfilled when the chopper and the detector are parallel to the sample-plane. The time-of-flight spectrum of the scattered neutrons is measured by the reverse time-of-flight method in which, instead of neutrons, one essentially records the modulation function of the chopper during constant periods preceding each detected neutron. With a Fourier chopper whose speed is varied in a suitable way, the method is equivalent to the conventional Fourier method but the spectrum is obtained directly without any off-line calculations. The new diffractometer is operated automatically by a Super Nova computer which not only accumulates the synthetized diffraction pattern but also controls the chopper speed according to the modulation frequency sweep chosen by the user to obtain a

Tempting to Tag : An Experimental Comparison of Four Tagging Input Mechanisms

OpenAIRE

Melenhorst, Mark; van Velsen, Lex

2010-01-01

Tagging helps achieve improved indexing and recommendation of resources (e.g., videos or pictures) in large data collections. In order to reap the benefits of tagging, people must be persuaded to label the resources they consume. This paper reports on a study in which four different tagging input mechanisms and their effect on users' motivation to tag were compared. The mechanisms consisted of a standard tag input box, a chatbot-like environment, a bookmarking mechanism, and a "tag and v...

Pulse Based Time-of-Flight Range Sensing.

Science.gov (United States)

Sarbolandi, Hamed; Plack, Markus; Kolb, Andreas

2018-05-23

Pulse-based Time-of-Flight (PB-ToF) cameras are an attractive alternative range imaging approach, compared to the widely commercialized Amplitude Modulated Continuous-Wave Time-of-Flight (AMCW-ToF) approach. This paper presents an in-depth evaluation of a PB-ToF camera prototype based on the Hamamatsu area sensor S11963-01CR. We evaluate different ToF-related effects, i.e., temperature drift, systematic error, depth inhomogeneity, multi-path effects, and motion artefacts. Furthermore, we evaluate the systematic error of the system in more detail, and introduce novel concepts to improve the quality of range measurements by modifying the mode of operation of the PB-ToF camera. Finally, we describe the means of measuring the gate response of the PB-ToF sensor and using this information for PB-ToF sensor simulation.

Thin Time-Of-Flight PET project

CERN Multimedia

The pre-R&D aims at designing and producing a compact and thin Time-Of-Flight PET detector device with depth of interaction measurement capability, which employs layered silicon sensors as active material, with a readout consisting of a new generation of very-low noise and very fast electronics based on SiGe Heterojunction Bipolar Transistors (HBT) components.

A suite of standard post-tagging evaluation metrics can help assess tag retention for field-based fish telemetry research

Science.gov (United States)

Gerber, Kayla M.; Mather, Martha E.; Smith, Joseph M.

2017-01-01

Telemetry can inform many scientific and research questions if a context exists for integrating individual studies into the larger body of literature. Creating cumulative distributions of post-tagging evaluation metrics would allow individual researchers to relate their telemetry data to other studies. Widespread reporting of standard metrics is a precursor to the calculation of benchmarks for these distributions (e.g., mean, SD, 95% CI). Here we illustrate five types of standard post-tagging evaluation metrics using acoustically tagged Blue Catfish (Ictalurus furcatus) released into a Kansas reservoir. These metrics included: (1) percent of tagged fish detected overall, (2) percent of tagged fish detected daily using abacus plot data, (3) average number of (and percent of available) receiver sites visited, (4) date of last movement between receiver sites (and percent of tagged fish moving during that time period), and (5) number (and percent) of fish that egressed through exit gates. These metrics were calculated for one to three time periods: early ( 5 days early in the study. On average, tagged Blue Catfish visited 9 (50%) and 13 (72%) of 18 within-reservoir receivers early and at the end of the study, respectively. At the end of the study, 73% of all tagged fish were detected moving between receivers. Creating statistical benchmarks for individual metrics can provide useful reference points. In addition, combining multiple metrics can inform ecology and research design. Consequently, individual researchers and the field of telemetry research can benefit from widespread, detailed, and standard reporting of post-tagging detection metrics.

Doppler time-of-flight imaging

KAUST Repository

Heidrich, Wolfgang

2017-02-16

Systems and methods for imaging object velocity are provided. In an embodiment, at least one Time-of-Flight camera is used to capture a signal representative of an object in motion over an exposure time. Illumination and modulation frequency of the captured motion are coded within the exposure time. A change of illumination frequency is mapped to measured pixel intensities of the captured motion within the exposure time, and information about a Doppler shift in the illumination frequency is extracted to obtain a measurement of instantaneous per pixel velocity of the object in motion. The radial velocity information of the object in motion can be simultaneously captured for each pixel captured within the exposure time. In one or more aspects, the illumination frequency can be coded orthogonal to the modulation frequency of the captured motion. The change of illumination frequency can correspond to radial object velocity.

A PCI time digitizer for the new JET time-of-flight neutron spectrometer

International Nuclear Information System (INIS)

Sousa, J.; Batista, A.J.N.; Combo, A.; Pereira, R.; Cruz, N.; Carvalho, P.; Varandas, C.A.F.; Conroy, S.; Ericsson, G.; Kaellne, J.

2004-01-01

A PCI time digitizer module with eight independent time-to-digital converter (TDC) channels is being developed for the new time-of-flight spectrometer designed for optimized rate (TOFOR) which diagnoses deuterium plasmas of the EFDA-JET tokamak. The module shall measure with high accuracy the flight-times of 2.5 MeV neutrons in the 100 ns range as given by two groups of scintillation detectors operating at average event rates from the expected 500 kHz up to 5 MHz. The module stores up to 64 million hit-times with a resolution of 0.4 ns and incorporates a digital signal processor and a system-on-chip device which performs the data transfer, the device control/monitoring and may perform statistical, data reduction or control algorithms in real-time

State-to-state dynamics of the H{sup *}(n) + HD → D{sup *}(n{sup ′}) + H{sub 2} reactive scattering

Energy Technology Data Exchange (ETDEWEB)

Yu, Shengrui; Su, Shu; Dai, Dongxu; Yuan, Kaijun, E-mail: kjyuan@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn; Yang, Xueming, E-mail: kjyuan@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China)

2014-01-21

The state-to-state dynamics of the H{sup *}(n) + HD → D{sup *}(n{sup ′}) + H{sub 2} reactive scattering at the collision energy of 0.5 eV have been carried out for the first time by using H-atom Rydberg tagging time-of-flight technique. Experimental results show that the angular distribution of the total H{sub 2} products presents clearly forward-backward asymmetric, which considerably differs from that of the corresponding H{sup +} + HD → D{sup +} + H{sub 2} reaction predicted by previously theoretical calculations. Such disagreement between these two processes suggests that the Fermi independent-collider model is also not valid in describing the dynamics of isotopic variants of the H{sup *} + H{sub 2} reaction. The rotational state distribution of the H{sub 2} products demonstrates a saw-toothed distribution with odd-j{sup ′} > even-j{sup ′}. This interesting observation is strongly influenced by nuclear spin statistics.

Time lens for high-resolution neutron time-of-flight spectrometers

International Nuclear Information System (INIS)

Baumann, K.; Gaehler, R.; Grigoriev, P.; Kats, E.I.

2005-01-01

We examine in analytic and numeric ways the imaging effects of temporal neutron lenses created by traveling magnetic fields. For fields of parabolic shape we derive the imaging equations, investigate the time magnification, the evolution of the phase-space element, the gain factor, and the effect of finite beam size. The main aberration effects are calculated numerically. The system is technologically feasible and should convert neutron time-of-flight instruments from pinhole to imaging configuration in time, thus enhancing intensity and/or time resolution. Further fields of application for high-resolution spectrometry may be opened

Real-time flavour tagging selection in ATLAS

CERN Document Server

Varni, Carlo; The ATLAS collaboration

2017-01-01

The ATLAS experiment includes a well-developed trigger system that allows a selection of events which are thought to be of interest, while achieving a high overall rejection against less interesting processes. An important part of the online event selection is the ability to distinguish between jets arising from heavy-flavour quarks (b- and c-jets) and light jets (jets from u-, d-, s- and gluon jets) in real-time. This is essential for many physics analysis that include processes with large jet multiplicity and b-quarks in the final state. An overview of the b-jet triggers with a description of the application and performance of the offline Multivariate (MV2) b-tagging algorithms at High Level Trigger (HLT) in Run 2 will be presented. During 2016 b-jet trigger menu and algorithms were adapted to use The Fast Tracker (FTK) system which will be commissioned in 2017. We will show initial expected performance of newly designed triggers and compare it with the existing HLT chains.

Time series analysis methods and applications for flight data

CERN Document Server

Zhang, Jianye

2017-01-01

This book focuses on different facets of flight data analysis, including the basic goals, methods, and implementation techniques. As mass flight data possesses the typical characteristics of time series, the time series analysis methods and their application for flight data have been illustrated from several aspects, such as data filtering, data extension, feature optimization, similarity search, trend monitoring, fault diagnosis, and parameter prediction, etc. An intelligent information-processing platform for flight data has been established to assist in aircraft condition monitoring, training evaluation and scientific maintenance. The book will serve as a reference resource for people working in aviation management and maintenance, as well as researchers and engineers in the fields of data analysis and data mining.

Preliminary test results of a flight management algorithm for fuel conservative descents in a time based metered traffic environment. [flight tests of an algorithm to minimize fuel consumption of aircraft based on flight time

Science.gov (United States)

Knox, C. E.; Cannon, D. G.

1979-01-01

A flight management algorithm designed to improve the accuracy of delivering the airplane fuel efficiently to a metering fix at a time designated by air traffic control is discussed. The algorithm provides a 3-D path with time control (4-D) for a test B 737 airplane to make an idle thrust, clean configured descent to arrive at the metering fix at a predetermined time, altitude, and airspeed. The descent path is calculated for a constant Mach/airspeed schedule from linear approximations of airplane performance with considerations given for gross weight, wind, and nonstandard pressure and temperature effects. The flight management descent algorithms and the results of the flight tests are discussed.

The ALICE Time of Flight Readout System AFRO

CERN Document Server

Kluge, A

1999-01-01

The ALICE Time of Flight Detector system comprises more than 100.000 channels and covers an area of more than 100 m2. The timing resolution should be better than 150 ps. This combination of requirements poses a major challenge to the readout system. All detector timing measurements are referenced to a unique start signal t0. This signal is generated at the time an event occurs. Timing measurements are performed using a multichannel TDC chip which requires a 40 MHz reference clock signal. The general concept of the readout system is based on a modular architecture. Detector cells are combined to modules of 1024 channels. Each of these modules can be read out and calibrated independently from each other. By distributing a reference signal, a timing relationship between the modules is established. This reference signal can either be the start signal t0 or the TDC-reference clock. The readout architecture is divided into three steps; the TDC controller, the module controller, and the time of flight controller. Th...

14 CFR 91.1057 - Flight, duty and rest time requirements: All crewmembers.

Science.gov (United States)

2010-01-01

... RULES Fractional Ownership Operations Program Management § 91.1057 Flight, duty and rest time... cabin-safety-related responsibilities. Multi-time zone flight means an easterly or westerly flight or... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Flight, duty and rest time requirements...

Dynamical continuous time random Lévy flights

Science.gov (United States)

Liu, Jian; Chen, Xiaosong

2016-03-01

The Lévy flights' diffusive behavior is studied within the framework of the dynamical continuous time random walk (DCTRW) method, while the nonlinear friction is introduced in each step. Through the DCTRW method, Lévy random walker in each step flies by obeying the Newton's Second Law while the nonlinear friction f(v) = - γ0v - γ2v3 being considered instead of Stokes friction. It is shown that after introducing the nonlinear friction, the superdiffusive Lévy flights converges, behaves localization phenomenon with long time limit, but for the Lévy index μ = 2 case, it is still Brownian motion.

Highly segmented, high resolution time-of-flight system

Energy Technology Data Exchange (ETDEWEB)

Nayak, T.K.; Nagamiya, S.; Vossnack, O.; Wu, Y.D.; Zajc, W.A. [Columbia Univ., New York, NY (United States); Miake, Y.; Ueno, S.; Kitayama, H.; Nagasaka, Y.; Tomizawa, K.; Arai, I.; Yagi, K [Univ. of Tsukuba, (Japan)

1991-12-31

The light attenuation and timing characteristics of time-of-flight counters constructed of 3m long scintillating fiber bundles of different shapes and sizes are presented. Fiber bundles made of 5mm diameter fibers showed good timing characteristics and less light attenuation. The results for a 1.5m long scintillator rod are also presented.

Molecular beam studies with a time-of-flight machine

International Nuclear Information System (INIS)

Beijerinck, H.C.W.

1975-01-01

The study concerns the development of the time-of-flight method for the velocity analysis of molecular beams and its application to the measurement of the velocity dependence of the total cross-section of the noble gases. It reviews the elastic scattering theory, both in the framework of classical mechanics and in the quantum mechanical description. Attention is paid to the semiclassical correspondence of classical particle trajectories with the partial waves of the quantum mechanical solution. The total cross-section and the small angle differential cross-section are discussed with special emphasis on their relation. The results of this chapter are used later to derive the correction on the measured total cross-section due to the finite angular resolution of the apparatus. Reviewed also is the available information on the intermolecular potential of the Ar-Ar system. Then a discussion of the measurement of total cross-sections with the molecular beam method and the time-of-flight method is compared to other methods used. It is shown that the single burst time-of-flight method can be developed into a reliable and well-calibrated method for the analysis of the velocity distribution of molecular beams. A comparison of the single burst time-of-flight method with the cross-correlation time-of-flight method shows that the two methods are complementary and that the specific experimental circumstances determine which method is to be preferred. Molecular beam sources are discussed. The peaking factor formalism is introduced and helps to compare the performance of different types of sources. The effusive and the supersonic source are treated and recent experimental results are given. The multichannel source is treated in more detail. For the opaque mode, an experimental investigation of the velocity distribution and the angular distribution of the flow pattern is presented. Comparison of these results with Monte Carlo calculations for free molecular flow in a cylindrical

Novel Real-Time Flight Envelope Monitoring System, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The proposed innovation is an aircraft flight envelope monitoring system that will provide real-time in-cockpit estimations of aircraft flight envelope boundaries....

Northern Pintail - Flight Path Telemetry [ds117

Data.gov (United States)

California Natural Resource Agency — North-south flight paths of radio-tagged female northern pintails were monitored in a section of Highway 152 near Los Banos, California during 4 and 11 November and...

Experiments with Rydberg atoms on a current-carrying atom chip

NARCIS (Netherlands)

Cisternas San Martín, N.V.

2018-01-01

On one side, atom-chip experiments have demonstrated to be a versatile tool to study quantum physics in cold atoms systems. On the other side, Rydberg atoms have exaggerated properties that makes them good candidates to study quantum information and quantum simulations protocols. In this thesis both

KELVIN rare gas time-of-flight program

International Nuclear Information System (INIS)

Vernon, M.

1981-03-01

The purpose of this appendix is to explain in detail the procedure for performing time-of-flight (TOF) calibration measurements. The result of the calibration measurements is to assign a correct length (L) to the path the molecules travel in a particular experimental configuration. In conjunction with time information (t) a velocity distribution (L/t) can then be determined. The program KELVIN is listed

Gas tagging system development in Japan

International Nuclear Information System (INIS)

Sekiguchi, N.; Rindo, H.; Akiyama, T.; Miyazawa, T.; Heki, H.

1981-05-01

The Gas tagging method has been considered to be most desirable for a failed fuel location system for the fast breeder reactor, regarding the component reduction in the reactor vessel and rapid location during reactor operation. The gas tagging system has been designed by referring to R and D results obtained in Japan and other countries. The designed system is comprised of tag gas filling pins, cover gas sampling system, tag gas recovery and enrichment system, tag gas analyzer and system control and data handling computers. The main specifications for this system have been decided as follows; 1) Main function is location of failed fuels in core and a part of blanket region, 2) Identification capability is each subassembly, 3) Time for identification is within a few days, 4) Continuous operation with automatic start at fuel failure, 5) Detection sensitivity must cover both gas leak and pin burst. In designing the gas tagging system, the following R and D items were selected; 1) System design study, 2) Tag gas capsule development, 3) Modeling the tag gas behavior in reactor primary cooling system, 4) Tag gas recovery and enrichment system, 5) Computer code development for tag gas isotope ratio change estimation. Details of the Japanese gas tagging system development appear in this paper. (author)

Time of flight imaging through scattering environments (Conference Presentation)

Science.gov (United States)

Le, Toan H.; Breitbach, Eric C.; Jackson, Jonathan A.; Velten, Andreas

2017-02-01

Light scattering is a primary obstacle to imaging in many environments. On small scales in biomedical microscopy and diffuse tomography scenarios scattering is caused by tissue. On larger scales scattering from dust and fog provide challenges to vision systems for self driving cars and naval remote imaging systems. We are developing scale models for scattering environments and investigation methods for improved imaging particularly using time of flight transient information. With the emergence of Single Photon Avalanche Diode detectors and fast semiconductor lasers, illumination and capture on picosecond timescales are becoming possible in inexpensive, compact, and robust devices. This opens up opportunities for new computational imaging techniques that make use of photon time of flight. Time of flight or range information is used in remote imaging scenarios in gated viewing and in biomedical imaging in time resolved diffuse tomography. In addition spatial filtering is popular in biomedical scenarios with structured illumination and confocal microscopy. We are presenting a combination analytical, computational, and experimental models that allow us develop and test imaging methods across scattering scenarios and scales. This framework will be used for proof of concept experiments to evaluate new computational imaging methods.

Detailed investigation of a time-of-flight neutron spectrometer

International Nuclear Information System (INIS)

Elevant, T.; Trostell, B.

1981-02-01

Properties of a neutron spectrometer and telescope, based on double neutron interaction in hydrogen based scintillators and neutron time-of-flight technique, have been investigated in detail. Theoretical scaling of the resolutions with the flight path length and scattering angle have been confirmed by experimental results. Important parameters in connection with calibration of the spectrometer are discussed and calculated relative resolutions of the ion temperature are shown when applied to a fusion deuterium plasma. (Auth.)

Optical spectroscopy of high-L Rydberg states of argon

International Nuclear Information System (INIS)

Wright, L. E.; Snow, E. L.; Lundeen, S. R.; Sturrus, W. G.

2007-01-01

High-L fine structure patterns in n=9 and n=17 Rydberg levels of argon have been studied using a Doppler-tuned CO 2 laser and a fast beam of argon atoms. Analysis of the measured pattern using the polarization model yields the scalar dipole polarizability and quadrupole moment of the 2 P 3 at ∼sol∼ at 2 Ar + ion. The results are α S =6.83(8)a 0 3 and Q=-0.5177(15)ea 0 2 . Within the precision of this study, no vector component of the structure was observed

Experimental efforts at NIST towards one-electron ions in circular Rydberg states

International Nuclear Information System (INIS)

Tan, Joseph N; Guise, Nicholas D; Brewer, Samuel M

2011-01-01

Experimental effort is underway at NIST to enable tests of theory with one-electron ions synthesized in circular Rydberg states from captured bare nuclei. Problematic effects that limit the accuracy of predicted energy levels for low-lying states are vanishingly small for high-angular-momentum (high-L) states; in particular, the nuclear size correction for high-L states is completely negligible for any foreseeable improvement of measurement precision. As an initial step towards realizing such states, highly charged ions are extracted from the NIST electron beam ion trap (EBIT) and steered through the electrodes of a Penning trap. The goal is to capture bare nuclei in the Penning trap for experiments to make one-electron atoms in circular Rydberg states with dipole (E1) transitions in the optical domain accessible to a frequency comb.

Time-of-flight trigger based on the use of the time-to-amplitude converter

International Nuclear Information System (INIS)

Ladygin, V.P.; Man'yakov, P.K.; Reznikov, S.G.

2000-01-01

The method of the time-of-flight trigger realization based on the use of the time-to-amplitude converter is described. Such a trigger has a short decision time and high efficiency of the useful event selection. (author)

14 CFR 121.503 - Flight time limitations: Pilots: airplanes.

Science.gov (United States)

2010-01-01

... Operations § 121.503 Flight time limitations: Pilots: airplanes. (a) A certificate holder conducting supplemental operations may schedule a pilot to fly in an airplane for eight hours or less during any 24... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Flight time limitations: Pilots: airplanes...

Time-of-flight mass spectrometer

International Nuclear Information System (INIS)

Ivanov, M.A.; Kozlov, B.N.; Mamyrin, B.A.; Shmikk, D.V.; Shebelin, V.G.

1981-01-01

A time-of-flight mass spectrometer containing a pulsed ion source with an electron gun and two electrodes limiting ionization range, drift space and ion acceptor, is described. To expand functional possibilities, a slot collimator of the gas stream, two quantum generators and two diaphragms for the inlet of quantum generator radiation located on both sides of the ion source, are introduced in the ion source. The above invention enables to study details of the complex interaction process of laser radiation with molecules of the gas stream, which is actual for laser isotope separation

Lamb shift of Rydberg atoms in a resonator

International Nuclear Information System (INIS)

Belov, A.A.; Lozovik, Yu.E.; Pokrovsky, V.L.

1988-08-01

The Lamb shift of a Rydberg atom in a cavity is shown to be enhanced with the resonance interaction of a virtual atomic transition and cavity modes. The dependence of the Lamb shift on quantum numbers and atomic number changes drastically. Shifting cavity walls and scanning the atomic beam one can vary the Lamb shift. The value of the Lamb shift in a cavity may exceed a typical magnitude of the fine structure energy. For a rough resonance tuning the Coulumb multiplet occurs to be strongly mixed and a novel classification is necessary. (author). 8 refs, 2 figs

The statistical chopper in the time-of-flight technique

International Nuclear Information System (INIS)

Albuquerque Vieira, J. de.

1975-12-01

A detailed study of the 'statistical' chopper and of the method of analysis of the data obtained by this technique is made. The study includes the basic ideas behind correlation methods applied in time-of-flight techniques; comparisons with the conventional chopper made by an analysis of statistical errors; the development of a FORTRAN computer programme to analyse experimental results; the presentation of the related fields of work to demonstrate the potential of this method and suggestions for future study together with the criteria for a time-of-flight experiment using the method being studied [pt

Time-of-Flight Adjustment Procedure for Acoustic Measurements in Structural Timber

Science.gov (United States)

Danbiel F. Llana; Guillermo Iñiguez-Gonzalez; Francisco Arriaga; Xiping Wang

2016-01-01

The effect of timber length on time-of-flight acoustic longitudinal measurements was investigated on the structural timber of four Spanish species: radiata pine (Pinus radiata D. Don), Scots pine (Pinus sylvestris L.), laricio pine (Pinus nigra Arn.), and maritime pine (Pinus pinaster Ait.). Time-of-flight longitudinal measurements were conducted on 120 specimens of...

Tag questions Tag questions

Directory of Open Access Journals (Sweden)

David Brazil

2008-04-01

Full Text Available The so-called 'tag' structures of English have received a lot of attention in language teaching programmes, attention that is not hard to justify when one considers the problems and anxiety they can occasion for many foreign learners. Most teachers one speaks to seem fairly willing to agree, however, that traditional treatments of the topic leave much to be desired. It happens, also, that, when considered collectively, the tags and some related phenomena have a special heoretical interest. For they constitute a field in which it seems essential to bring together insights that derive from the study of several aspects of linguistic organisation, aspects which in some recent work have been held to need distinctive kinds of descriptive category to handle. Traditional treatments have found it necessary to recognise different syntactic types (e.g. 'same polarity' and 'reversed polarity' tags and ifferent intonational treatments ("falling'and 'rising' tag; while the way the communicative significance of the various permutations is described normally requires reference to the expectations they signal regarding the immediately following behaviour of the other party (in the common phrase, 'What kind of answer they expect'. This last consideration places the matter squarely in the arena of recent work on the analysis of interactive discourse. The so-called 'tag' structures of English have received a lot of attention in language teaching programmes, attention that is not hard to justify when one considers the problems and anxiety they can occasion for many foreign learners. Most teachers one speaks to seem fairly willing to agree, however, that traditional treatments of the topic leave much to be desired. It happens, also, that, when considered collectively, the tags and some related phenomena have a special heoretical interest. For they constitute a field in which it seems essential to bring together insights that derive from the study of several aspects

Observation of electric quadrupole transitions to Rydberg nd states of ultracold rubidium atoms

NARCIS (Netherlands)

Tong, D.; Farooqi, S.M.; Kempen, van E.G.M.; Pavlovic, Z.; Stanojevic, J.; Coté, R.; Eyler, E.E.; Gould, P.L.

2009-01-01

We report the observation of dipole-forbidden, but quadrupole-allowed, one-photon transitions to high-Rydberg states in Rb. Using pulsed uv excitation of ultracold atoms in a magneto-optical trap, we excite 5s¿nd transitions over a range of principal quantum numbers n=27–59. Compared to

IceBridge Sigma Space Lidar L0 Raw Time-of-Flight Data

Data.gov (United States)

National Aeronautics and Space Administration — The NASA IceBridge Sigma Space Lidar L0 Raw Time-of-Flight Data (ILSIG0) contain raw time-of-flight values for Antarctica and Greenland using the Sigma Space Lidar....

A universal representation of Rydberg spectral line shapes in plasmas

International Nuclear Information System (INIS)

Mosse, C.; Calisti, A.; Stamm, R.; Talin, B.; Bureyeva, L.; Lisitsa, V. S.

2001-01-01

A universal representation of Rydberg atom line shapes in plasmas is obtained. It bases on analytical formulas for intensity distribution in radiation transitions n→n' between highly excited atomic states with large values of principle quantum numbers n, n'>>1, Δn=n-n'<< n and the frequency fluctuation model (FFM) for account of ion thermal motion effects. The line shapes are presented in a universal manner as functions of plasma temperatures and densities

Calibration and adjustment of the EGRET coincidence/time-of-flight system

International Nuclear Information System (INIS)

Hunter, S.D.

1991-01-01

The coincidence/time-of-flight system of the energetic gamma ray experiment telescope (EGRET) on NASA's Gamma Ray Observatory (GRO) consists of two layers of sixteen scintillator tiles. These tiles are paired into 96 coincidence telescopes. Valid coincidence and time-of-flight values (indicating downward moving particles) from one of these telescopes are two of the requirements for an EGRET event trigger. To maximize up-down discrimination, variations in the mean timing value of the telescopes must be minimized. The timing values of the 96 telescopes are not independent, hence they cannot be individually adjusted to calibrate the system. An iterative approach was devised to determine adjustments to the length of the photomultiplier signal cables. These adjustments were made directly in units of time using a time domain reflectometry technique, by timing the reflection of a fast pulse from the unterminated end of eable, and observing the charge in signal propagation time as the length of the cable was shortened. Two constant fraction discriminators, a time-to-amplitude converter and a pulse height analyzer were used for these measurements. Using this direct time measuring approach, the timing values for the 96 EGRET coincidence/time-of-flight telescopes were adjusted with an FWHM variation of less than 450 ps (± 1 TOF timing channel). (orig.)

Testing the time-of-flight model for flagellar length sensing.

Science.gov (United States)

Ishikawa, Hiroaki; Marshall, Wallace F

2017-11-07

Cilia and flagella are microtubule-based organelles that protrude from the surface of most cells, are important to the sensing of extracellular signals, and make a driving force for fluid flow. Maintenance of flagellar length requires an active transport process known as intraflagellar transport (IFT). Recent studies reveal that the amount of IFT injection negatively correlates with the length of flagella. These observations suggest that a length-dependent feedback regulates IFT. However, it is unknown how cells recognize the length of flagella and control IFT. Several theoretical models try to explain this feedback system. We focused on one of the models, the "time-of-flight" model, which measures the length of flagella on the basis of the travel time of IFT protein in the flagellar compartment. We tested the time-of-flight model using Chlamydomonas dynein mutant cells, which show slower retrograde transport speed. The amount of IFT injection in dynein mutant cells was higher than that in control cells. This observation does not support the prediction of the time-of-flight model and suggests that Chlamydomonas uses another length-control feedback system rather than that described by the time-of-flight model. © 2017 Ishikawa and Marshall. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

CT colonography with rectal iodine tagging: Feasibility and comparison with oral tagging in a colorectal cancer screening population

International Nuclear Information System (INIS)

Neri, Emanuele; Mantarro, Annalisa; Faggioni, Lorenzo; Scalise, Paola; Bemi, Pietro; Pancrazi, Francesca; D’Ippolito, Giuseppe; Bartolozzi, Carlo

2015-01-01

Highlights: • In the group receiving rectal tagging, mean per-polyp sensitivity, specificity were 96.1% and 95.3%; while in the group receiving oral tagging, mean per-polyp sensitivity, specificity were 89.4% and 95.8%. The difference between the two groups was not statistically significant (p = 0.549). • Rectal tagging can be an effective alternative to oral tagging. • Rectal tagging allowed greater patient acceptance and lower overall examination time. - Abstract: Purpose: To evaluate feasibility, diagnostic performance, patient acceptance, and overall examination time of CT colonography (CTC) performed through rectal administration of iodinated contrast material. Materials and methods: Six-hundred asymptomatic subjects (male:female = 270:330; mean 63 years) undergoing CTC for colorectal cancer screening on an individual basis were consecutively enrolled in the study. Out of them, 503 patients (group 1) underwent CTC with rectal tagging, of which 55 had a total of 77 colonic lesions. The remaining 97 patients (group 2) were randomly selected to receive CTC with oral tagging of which 15 had a total of 20 colonic lesions. CTC findings were compared with optical colonoscopy, and per-segment image quality was visually assessed using a semi-quantitative score (1 = poor, 2 = adequate, 3 = excellent). In 70/600 patients (11.7%), CTC was performed twice with both types of tagging over a 5-year follow-up cancer screening program. In this subgroup, patient acceptance was rated via phone interview two weeks after CTC using a semi-quantitative scale (1 = poor, 2 = fair, 3 = average, 4 = good, 5 = excellent). Results: Mean per-polyp sensitivity, specificity, positive and negative predictive values of CTC with rectal vs oral tagging were 96.1% (CI 95% 85.4 ÷ 99.3%) vs 89.4% (CI 95% 65.4 ÷ 98.1%), 95.3% (CI 95% 90.7 ÷ 97.8%) vs 95.8% (CI 95% 87.6 ÷ 98.9%), 86.0% (CI 95% 73.6 ÷ 93.3) vs 85.0% (CI 95% 61.1 ÷ 96.0%), and 98.8% (CI 95% 95.3 ÷ 99.8%) vs 97.2% (CI 95% 89

CT colonography with rectal iodine tagging: Feasibility and comparison with oral tagging in a colorectal cancer screening population

Energy Technology Data Exchange (ETDEWEB)

Neri, Emanuele, E-mail: emanuele.neri@med.unipi.it [Diagnostic and Interventional Radiology – Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa (Italy); Mantarro, Annalisa; Faggioni, Lorenzo; Scalise, Paola; Bemi, Pietro; Pancrazi, Francesca [Diagnostic and Interventional Radiology – Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa (Italy); D’Ippolito, Giuseppe [Federal University of São Paulo – Sena Madureira 1500 – Vila Mariana, UNIFESP, São Paulo, SP (Brazil); Bartolozzi, Carlo [Diagnostic and Interventional Radiology – Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa (Italy)

2015-09-15

Highlights: • In the group receiving rectal tagging, mean per-polyp sensitivity, specificity were 96.1% and 95.3%; while in the group receiving oral tagging, mean per-polyp sensitivity, specificity were 89.4% and 95.8%. The difference between the two groups was not statistically significant (p = 0.549). • Rectal tagging can be an effective alternative to oral tagging. • Rectal tagging allowed greater patient acceptance and lower overall examination time. - Abstract: Purpose: To evaluate feasibility, diagnostic performance, patient acceptance, and overall examination time of CT colonography (CTC) performed through rectal administration of iodinated contrast material. Materials and methods: Six-hundred asymptomatic subjects (male:female = 270:330; mean 63 years) undergoing CTC for colorectal cancer screening on an individual basis were consecutively enrolled in the study. Out of them, 503 patients (group 1) underwent CTC with rectal tagging, of which 55 had a total of 77 colonic lesions. The remaining 97 patients (group 2) were randomly selected to receive CTC with oral tagging of which 15 had a total of 20 colonic lesions. CTC findings were compared with optical colonoscopy, and per-segment image quality was visually assessed using a semi-quantitative score (1 = poor, 2 = adequate, 3 = excellent). In 70/600 patients (11.7%), CTC was performed twice with both types of tagging over a 5-year follow-up cancer screening program. In this subgroup, patient acceptance was rated via phone interview two weeks after CTC using a semi-quantitative scale (1 = poor, 2 = fair, 3 = average, 4 = good, 5 = excellent). Results: Mean per-polyp sensitivity, specificity, positive and negative predictive values of CTC with rectal vs oral tagging were 96.1% (CI{sub 95%} 85.4 ÷ 99.3%) vs 89.4% (CI{sub 95%} 65.4 ÷ 98.1%), 95.3% (CI{sub 95%} 90.7 ÷ 97.8%) vs 95.8% (CI{sub 95%} 87.6 ÷ 98.9%), 86.0% (CI{sub 95%} 73.6 ÷ 93.3) vs 85.0% (CI{sub 95%} 61.1 ÷ 96.0%), and 98.8% (CI{sub 95

Radio-over-fiber using an optical antenna based on Rydberg states of atoms

Science.gov (United States)

Deb, A. B.; Kjærgaard, N.

2018-05-01

We provide an experimental demonstration of a direct fiber-optic link for RF transmission ("radio-over-fiber") using a sensitive optical antenna based on a rubidium vapor cell. The scheme relies on measuring the transmission of laser light at an electromagnetically induced transparency resonance that involves highly excited Rydberg states. By dressing pairs of Rydberg states using microwave fields that act as local oscillators, we encoded RF signals in the optical frequency domain. The light carrying the information is linked via a virtually lossless optical fiber to a photodetector where the signal is retrieved. We demonstrate a signal bandwidth in excess of 1 MHz limited by the available coupling laser power and atomic optical density. Our sensitive, non-metallic and readily scalable optical antenna for microwaves allows extremely low-levels of optical power (˜1 μW) throughput in the fiber-optic link. It offers a promising future platform for emerging wireless network infrastructures.

Time-of-flight positron emission tomography and associated detectors

International Nuclear Information System (INIS)

Vacher, J.; Allemand, R.; Campagnolo, R.

1983-04-01

An analysis of the timing capabilities of the detectors (scintillators and photomultipliers) in time-of-flight positron emission tomography is presented. The advantages of BaF 2 compared with CsF for the futur tomographs are evaluated [fr

Inhomogeneous oscillatory electric field time-of-flight mass spectrometer

International Nuclear Information System (INIS)

Carrico, J.P.

1977-01-01

The mass-to-charge ratio of an ion can be determined from the measurement of its flight time in an inhomogeneous, oscillatory electric field produced by the potential distribution V(x, y, t) = Vsub(DC) + Vsub(AC) cos ωt) (αsub(x)X 2 + αsub(y)Y 2 + αsub(z)Z 2 ). The governing equation of motion is the Mathieu equation. The principle of operation of this novel mass spectrometer is described and results of computer calculations of the flight time and resolution are reported. An experimental apparatus and results and results demonstrating the feasibility of this mass spectrometer principle are described. (author)

A time of flight detector for high energy heavy particles

Energy Technology Data Exchange (ETDEWEB)

Fang, Z.; O`Connor, D.J. [Newcastle Univ., NSW (Australia). Dept. of Physics

1993-12-31

As a commonly used method to measure the energy of a particle with known mass, the flight time of the particle travelling over a certain distance is measured. A detector based on this principle is called a time-of-flight (TOF) detector which has attracted interests constantly during the last 15 years. For high energy heavy particle energy detection, TOF detector is an appropriated choice and such a system, developed recently, is described in this paper. 8 refs., 3 figs.

A time of flight detector for high energy heavy particles

Energy Technology Data Exchange (ETDEWEB)

Fang, Z; O` Connor, D J [Newcastle Univ., NSW (Australia). Dept. of Physics

1994-12-31

As a commonly used method to measure the energy of a particle with known mass, the flight time of the particle travelling over a certain distance is measured. A detector based on this principle is called a time-of-flight (TOF) detector which has attracted interests constantly during the last 15 years. For high energy heavy particle energy detection, TOF detector is an appropriated choice and such a system, developed recently, is described in this paper. 8 refs., 3 figs.

A Time-of-Flight System for Low Energy Charged Particles

Science.gov (United States)

Giordano, Micheal; Sadwick, Krystalyn; Fletcher, Kurt; Padalino, Stephen

2013-10-01

A time-of-flight system has been developed to measure the energy of charged particles in the keV range. Positively charged ions passing through very thin carbon films mounted on grids generate secondary electrons. These electrons are accelerated by a -2000 V grid bias towards a grounded channeltron electron multiplier (CEM) which amplifies the signal. Two CEM detector assemblies are mounted 23.1 cm apart along the path of the ions. An ion generates a start signal by passing through the first CEM and a stop signal by passing through the second. The start and stop signals generate a time-of-flight spectrum via conventional electronics. Higher energy alpha particles from radioactive sources have been used to test the system. This time-of-flight system will be deployed to measure the energies of 15 to 30 keV ions produced by a duoplasmatron ion source that is used to characterize ICF detectors.

Engineering the ATLAS TAG Browser

CERN Document Server

Zhang, Q; The ATLAS collaboration

2011-01-01

ELSSI is a web-based event metadata (TAG) browser and event-level selection service for ATLAS. TAGs from all ATLAS physics and Monte Carlo data sets are routinely loaded into Oracle databases as an integral part of event processing. As data volumes increase, more and more sites are joining the distributed TAG data hosting topology. Meanwhile, TAG content and database schemata continue to evolve as new user requirements and additional sources of metadata emerge. All of this has posed many challenges to the development of ELSSI, which must support vast amounts of TAG data while source, content, geographic locations, and user query patterns may change over time. In this paper, we describe some of the challenges encountered in the process of developing ELSSI, and the software engineering strategies adopted to address those challenges. Approaches to management of access to data, browsing, data rendering, query building, query validation, execution, connection management, and communication with auxiliary services a...

Engineering the ATLAS TAG Browser

CERN Document Server

Zhang, Q; The ATLAS collaboration

2011-01-01

ELSSI is a web-based event metadata (TAG) browser and event-level selection service for ATLAS. TAGs from all ATLAS physics and Monte Carlo data sets are routinely loaded into Oracle databases as an integral part of event processing. As data volumes increase, more and more sites are joining the distributed TAG data hosting topology[1]. Meanwhile, TAG content and database schemata continue to evolve as new user requirements and additional sources of metadata emerge. All of this has posed many challenges to the development of ELSSI, which must support vast amounts of TAG data while source, content, geographic locations, and user query patterns may change over time. In this paper, we describe some of the challenges encountered in the process of developing ELSSI, and the software engineering strategies adopted to address those challenges. Approaches to management of access to data, browsing, data rendering, query building, query validation, execution, connection management, and communication with auxiliary service...

Real-time ultrasound-tagging to track the 2D motion of the common carotid artery wall in vivo

Energy Technology Data Exchange (ETDEWEB)

Zahnd, Guillaume, E-mail: g.zahnd@erasmusmc.nl [Biomedical Imaging Group Rotterdam, Departments of Radiology and Medical Informatics, Erasmus MC, Rotterdam 3000 CA (Netherlands); Salles, Sébastien; Liebgott, Hervé; Vray, Didier [Université de Lyon, CREATIS, CNRS UMR 5220, INSERM U1044, INSA-Lyon, Université Lyon 1, Lyon 69100 (France); Sérusclat, André [Department of Radiology, Louis Pradel Hospital, Lyon 69500 (France); Moulin, Philippe [Department of Endocrinology, Louis Pradel Hospital, Hospices Civils de Lyon, Université Lyon 1, Lyon 69100, France and INSERM UMR 1060, Lyon 69500 (France)

2015-02-15

Purpose: Tracking the motion of biological tissues represents an important issue in the field of medical ultrasound imaging. However, the longitudinal component of the motion (i.e., perpendicular to the beam axis) remains more challenging to extract due to the rather coarse resolution cell of ultrasound scanners along this direction. The aim of this study is to introduce a real-time beamforming strategy dedicated to acquire tagged images featuring a distinct pattern in the objective to ease the tracking. Methods: Under the conditions of the Fraunhofer approximation, a specific apodization function was applied to the received raw channel data, in real-time during image acquisition, in order to introduce a periodic oscillations pattern along the longitudinal direction of the radio frequency signal. Analytic signals were then extracted from the tagged images, and subpixel motion tracking of the intima–media complex was subsequently performed offline, by means of a previously introduced bidimensional analytic phase-based estimator. Results: The authors’ framework was applied in vivo on the common carotid artery from 20 young healthy volunteers and 6 elderly patients with high atherosclerosis risk. Cine-loops of tagged images were acquired during three cardiac cycles. Evaluated against reference trajectories manually generated by three experienced analysts, the mean absolute tracking error was 98 ± 84 μm and 55 ± 44 μm in the longitudinal and axial directions, respectively. These errors corresponded to 28% ± 23% and 13% ± 9% of the longitudinal and axial amplitude of the assessed motion, respectively. Conclusions: The proposed framework enables tagged ultrasound images of in vivo tissues to be acquired in real-time. Such unconventional beamforming strategy contributes to improve tracking accuracy and could potentially benefit to the interpretation and diagnosis of biomedical images.

Investigation of the Impact of Different Terms in the Second Order Hamiltonian on Excitation Energies of Valence and Rydberg States.

Science.gov (United States)

Tajti, Attila; Szalay, Péter G

2016-11-08

Describing electronically excited states of molecules accurately poses a challenging problem for theoretical methods. Popular second order techniques like Linear Response CC2 (CC2-LR), Partitioned Equation-of-Motion MBPT(2) (P-EOM-MBPT(2)), or Equation-of-Motion CCSD(2) (EOM-CCSD(2)) often produce results that are controversial and are ill-balanced with their accuracy on valence and Rydberg type states. In this study, we connect the theory of these methods and, to investigate the origin of their different behavior, establish a series of intermediate variants. The accuracy of these on excitation energies of singlet valence and Rydberg electronic states is benchmarked on a large sample against high-accuracy Linear Response CC3 references. The results reveal the role of individual terms of the second order similarity transformed Hamiltonian, and the reason for the bad performance of CC2-LR in the description of Rydberg states. We also clarify the importance of the T̂ 1 transformation employed in the CC2 procedure, which is found to be very small for vertical excitation energies.

Material Classification Using Raw Time-of-Flight Measurements

KAUST Repository

Su, Shuochen; Heide, Felix; Swanson, Robin J.; Klein, Jonathan; Callenberg, Clara; Hullin, Matthias; Heidrich, Wolfgang

2016-01-01

We propose a material classification method using raw time-of-flight (ToF) measurements. ToF cameras capture the correlation between a reference signal and the temporal response of material to incident illumination. Such measurements encode unique

Timing performances of a data acquisition system for Time of Flight PET

International Nuclear Information System (INIS)

Morrocchi, Matteo; Marcatili, Sara; Belcari, Nicola; Bisogni, Maria G.; Collazuol, Gianmaria; Ambrosi, Giovanni; Corsi, Francesco; Foresta, Maurizio; Marzocca, Cristoforo; Matarrese, Gianvito; Sportelli, Giancarlo; Guerra, Pedro; Santos, Andres; Del Guerra, Alberto

2012-01-01

We are investigating the performances of a data acquisition system for Time of Flight PET, based on LYSO crystal slabs and 64 channels Silicon Photomultipliers matrices (1.2 cm 2 of active area each). Measurements have been performed to test the timing capability of the detection system (SiPM matices coupled to a LYSO slab and the read-out electronics) with both test signal and radioactive source.

ATLAS - analysis of time-of-flight diffraction data from liquid and amorphous samples

International Nuclear Information System (INIS)

Soper, A.K.; Howells, W.S.; Hannon, A.C.

1989-05-01

The purpose of this manual is to describe a package of data analysis routines which have been developed at the Rutherford Appleton Laboratory for the analysis of time-of-flight diffraction data from liquids, gases, and amorphous materials. There is no fundamental barrier to diffraction data being accurately analysed to structure factor or even pair correlation function within a very short time of the completion of the experiment. Section 1 describes the time-of-flight neutron diffraction experiment and looks at diffraction theory. Section 2 indicates the steps in data analysis of time-of-flight diffraction data and Section 3 gives details of how to run the procedures. (author)

A Four-Gap Glass-RPC Time-of-Flight Array with 90 ps Time Resolution

CERN Document Server

Akindinov, A; Formenti, F; Golovine, V; Klempt, W; Kluge, A; Martemyanov, A N; Martinengo, P; Pinhão, J; Smirnitsky, A V; Spegel, M; Szymanski, P; Zalipska, J

2001-01-01

In this paper, we describe the performance of a prototype developed in the context of the ALICE time-of-flight research and development system. The detector module consists of a 32-channel array of 3 x 3 cm2 glass resistive plate chamber (RPC) cells, each of which has four accurately space gaps of 0.3 mm thickness arranged as a pair of double-gap resisitive plate chambers. Operated with a nonflammable gas mixture at atmospheric pressure, the system achieved a time resolution of 90 ps at 98% efficiency with good uniformity and moderate crosstalk. This result shows the feasibility of large-area high-resolution time-of-flight systems based on RPCs at affordable cost.

A theoretical investigation of valence and Rydberg electronic states of acrolein

International Nuclear Information System (INIS)

Aquilante, Francesco; Barone, Vincenzo; Roos, Bjoern O.

2003-01-01

The main features of the ultraviolet spectrum of acrolein have been studied by a multireference perturbative treatment and by a time dependent density functional approach. The valence and Rydberg transition energies have been calculated and the assignment of the experimental bands has been clarified. The different relaxation trends of the three lowest singlet and triplet excited states have been analyzed by unconstrained geometry optimizations. This has allowed, in particular, the characterization of a twisted 3 (ππ*) state, which is crucial for the interesting photophysics and photochemistry of the acrolein molecule and, more generally, of the α,β-enones. Solvatochromic shifts in aqueous solution have been investigated using a combined discrete/continuum approach based on the so called polarizable continuum model. The experimental trends are well reproduced by this approach and a closer degeneracy in the triplet manifold has been detected in solution with respect to gas phase

High performance real-time flight simulation at NASA Langley

Science.gov (United States)

Cleveland, Jeff I., II

1994-01-01

In order to meet the stringent time-critical requirements for real-time man-in-the-loop flight simulation, computer processing operations must be deterministic and be completed in as short a time as possible. This includes simulation mathematical model computational and data input/output to the simulators. In 1986, in response to increased demands for flight simulation performance, personnel at NASA's Langley Research Center (LaRC), working with the contractor, developed extensions to a standard input/output system to provide for high bandwidth, low latency data acquisition and distribution. The Computer Automated Measurement and Control technology (IEEE standard 595) was extended to meet the performance requirements for real-time simulation. This technology extension increased the effective bandwidth by a factor of ten and increased the performance of modules necessary for simulator communications. This technology is being used by more than 80 leading technological developers in the United States, Canada, and Europe. Included among the commercial applications of this technology are nuclear process control, power grid analysis, process monitoring, real-time simulation, and radar data acquisition. Personnel at LaRC have completed the development of the use of supercomputers for simulation mathematical model computational to support real-time flight simulation. This includes the development of a real-time operating system and the development of specialized software and hardware for the CAMAC simulator network. This work, coupled with the use of an open systems software architecture, has advanced the state of the art in real time flight simulation. The data acquisition technology innovation and experience with recent developments in this technology are described.

FLIGHT RANGE OF AFRICANIZED HONEYBEES, Apis mellifera L. 1758 (Hymenoptera: Apidae IN AN APPLE GROVE

Directory of Open Access Journals (Sweden)

PARANHOS B.A.J

1997-01-01

Full Text Available Africanized honeybees from five colonies were marked with P-32 and taken to an apple grove for a flight behavior study. The method used to determine the flight range was to put out an array of tagged trees in a cross pattern with the colonies arranged in the center point of a 0.8 ha test area. The tagged trees were located 10 meters apart in the 4 rows of 50 meters each, arranged according to the North, South, East, and West directions. Bees were collected while visiting the tagged tree flowers twice a day, during a ten-day period. The number of honeybees marked decreased in relation to the distance from the hives. Analysis of variance showed that a linear regression was highly significant to describe the process. Geographic directions did not affect the activity of the bees.

Adiabatic potential-energy curves of long-range Rydberg molecules: Two-electron R -matrix approach

Czech Academy of Sciences Publication Activity Database

Tarana, Michal; Čurík, Roman

2016-01-01

Roč. 93, č. 1 (2016), 012515 ISSN 0556-2791 R&D Projects: GA ČR(CZ) GP14-15989P Institutional support: RVO:61388955 Keywords : adiabatic-potential- energy curves * Rydberg molecules * theoretical chemistry Subject RIV: CF - Physical ; Theoretical Chemistry

Adiabatic potential-energy curves of long-range Rydberg molecules: Two-electron R -matrix approach

Czech Academy of Sciences Publication Activity Database

Tarana, Michal; Čurík, Roman

2016-01-01

Roč. 93, č. 1 (2016), 012515 ISSN 0556-2791 R&D Projects: GA ČR(CZ) GP14-15989P Institutional support: RVO:61388955 Keywords : adiabatic-potential-energy curves * Rydberg molecules * theoretical chemistry Subject RIV: CF - Physical ; Theoretical Chemistry

Inclusive Flavour Tagging Algorithm

International Nuclear Information System (INIS)

Likhomanenko, Tatiana; Derkach, Denis; Rogozhnikov, Alex

2016-01-01

Identifying the flavour of neutral B mesons production is one of the most important components needed in the study of time-dependent CP violation. The harsh environment of the Large Hadron Collider makes it particularly hard to succeed in this task. We present an inclusive flavour-tagging algorithm as an upgrade of the algorithms currently used by the LHCb experiment. Specifically, a probabilistic model which efficiently combines information from reconstructed vertices and tracks using machine learning is proposed. The algorithm does not use information about underlying physics process. It reduces the dependence on the performance of lower level identification capacities and thus increases the overall performance. The proposed inclusive flavour-tagging algorithm is applicable to tag the flavour of B mesons in any proton-proton experiment. (paper)

Extracting Tag Hierarchies

Science.gov (United States)

Tibély, Gergely; Pollner, Péter; Vicsek, Tamás; Palla, Gergely

2013-01-01

Tagging items with descriptive annotations or keywords is a very natural way to compress and highlight information about the properties of the given entity. Over the years several methods have been proposed for extracting a hierarchy between the tags for systems with a "flat", egalitarian organization of the tags, which is very common when the tags correspond to free words given by numerous independent people. Here we present a complete framework for automated tag hierarchy extraction based on tag occurrence statistics. Along with proposing new algorithms, we are also introducing different quality measures enabling the detailed comparison of competing approaches from different aspects. Furthermore, we set up a synthetic, computer generated benchmark providing a versatile tool for testing, with a couple of tunable parameters capable of generating a wide range of test beds. Beside the computer generated input we also use real data in our studies, including a biological example with a pre-defined hierarchy between the tags. The encouraging similarity between the pre-defined and reconstructed hierarchy, as well as the seemingly meaningful hierarchies obtained for other real systems indicate that tag hierarchy extraction is a very promising direction for further research with a great potential for practical applications. Tags have become very prevalent nowadays in various online platforms ranging from blogs through scientific publications to protein databases. Furthermore, tagging systems dedicated for voluntary tagging of photos, films, books, etc. with free words are also becoming popular. The emerging large collections of tags associated with different objects are often referred to as folksonomies, highlighting their collaborative origin and the “flat” organization of the tags opposed to traditional hierarchical categorization. Adding a tag hierarchy corresponding to a given folksonomy can very effectively help narrowing or broadening the scope of search

Extracting tag hierarchies.

Directory of Open Access Journals (Sweden)

Gergely Tibély

Full Text Available Tagging items with descriptive annotations or keywords is a very natural way to compress and highlight information about the properties of the given entity. Over the years several methods have been proposed for extracting a hierarchy between the tags for systems with a "flat", egalitarian organization of the tags, which is very common when the tags correspond to free words given by numerous independent people. Here we present a complete framework for automated tag hierarchy extraction based on tag occurrence statistics. Along with proposing new algorithms, we are also introducing different quality measures enabling the detailed comparison of competing approaches from different aspects. Furthermore, we set up a synthetic, computer generated benchmark providing a versatile tool for testing, with a couple of tunable parameters capable of generating a wide range of test beds. Beside the computer generated input we also use real data in our studies, including a biological example with a pre-defined hierarchy between the tags. The encouraging similarity between the pre-defined and reconstructed hierarchy, as well as the seemingly meaningful hierarchies obtained for other real systems indicate that tag hierarchy extraction is a very promising direction for further research with a great potential for practical applications. Tags have become very prevalent nowadays in various online platforms ranging from blogs through scientific publications to protein databases. Furthermore, tagging systems dedicated for voluntary tagging of photos, films, books, etc. with free words are also becoming popular. The emerging large collections of tags associated with different objects are often referred to as folksonomies, highlighting their collaborative origin and the "flat" organization of the tags opposed to traditional hierarchical categorization. Adding a tag hierarchy corresponding to a given folksonomy can very effectively help narrowing or broadening the scope of

Extracting tag hierarchies.

Science.gov (United States)

Tibély, Gergely; Pollner, Péter; Vicsek, Tamás; Palla, Gergely

2013-01-01

Tagging items with descriptive annotations or keywords is a very natural way to compress and highlight information about the properties of the given entity. Over the years several methods have been proposed for extracting a hierarchy between the tags for systems with a "flat", egalitarian organization of the tags, which is very common when the tags correspond to free words given by numerous independent people. Here we present a complete framework for automated tag hierarchy extraction based on tag occurrence statistics. Along with proposing new algorithms, we are also introducing different quality measures enabling the detailed comparison of competing approaches from different aspects. Furthermore, we set up a synthetic, computer generated benchmark providing a versatile tool for testing, with a couple of tunable parameters capable of generating a wide range of test beds. Beside the computer generated input we also use real data in our studies, including a biological example with a pre-defined hierarchy between the tags. The encouraging similarity between the pre-defined and reconstructed hierarchy, as well as the seemingly meaningful hierarchies obtained for other real systems indicate that tag hierarchy extraction is a very promising direction for further research with a great potential for practical applications. Tags have become very prevalent nowadays in various online platforms ranging from blogs through scientific publications to protein databases. Furthermore, tagging systems dedicated for voluntary tagging of photos, films, books, etc. with free words are also becoming popular. The emerging large collections of tags associated with different objects are often referred to as folksonomies, highlighting their collaborative origin and the "flat" organization of the tags opposed to traditional hierarchical categorization. Adding a tag hierarchy corresponding to a given folksonomy can very effectively help narrowing or broadening the scope of search. Moreover

Timing performances of a data acquisition system for Time of Flight PET