International Nuclear Information System (INIS)

Mini-LIA is a miniature of a linear induction accelerator developed by China Academy of Engineering Physics and Tsinghua University in 2007. It has been constructed with a thermionic cathode in an electron injector and a metglas core in the induction accelerator cavities. A double-pulsed electron beam was produced for the first time in China on the Mini-LIA with a thermionic cathode in the electron gun and a metglas core in the induction accelerator cavities. A double-pulsed beam current of more than 1.1A was obtained on condition of 80 kV double-pulsed high voltage produced by pulsed power system supplying to the injector and accelerating modules. Some primary experiments for measuring the parameters of Mini-LIA has been performed, and some beam characterizations of Mini-LIA are presented. Further improvement is underway. (authors)

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Abstract Background and Purpose: During laser lithotripsy, working instruments are often in close proximity to the distal fiber tip and may be damaged accidentally or even intentionally. The aim of this study was to compare the amount of damage to a standard guidewire and the nitinol wires of endourologic retrieval baskets that were affected by three different clinically available laser systems. Materials and Methods: The impact of pulsed laser irradiation on a standard hydrophilic guidewire and a retrieval basket were investigated. One infrared (IR) laser system (holmium:yttrium-aluminum-garnet [Ho:YAG]: ????=???2100???nm) and two laser systems emitting light in the visible (VIS) spectral range (frequency-doubled double-pulse neodymium:YAG [FREDDY]: ????=???532???nm/1064???nm and flashl...

Science.gov (United States)

... The acousto-optic device have a 30 MHz 1 ... coherent systems including compact non-coherent optical ... a relatively simple phase switching approach. ...

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Energy Technology Data Exchange (ETDEWEB)

The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) based on the final kilometer of the Stanford Linear Accelerator. One of the most critical diagnostic devices is the bunch length monitor (BLM), which is to be installed right after each compressor utilizing coherent radiation from the last bending magnet. We describe the components and the optical layout of such a BLM. Based on the setup geometry, we discuss some issues about the coherent radiation signal.

UK PubMed Central (United Kingdom)

PurposeTo describe ocular findings for a 34-year-old man with chronic solar retinopathy using high-speed ultrahigh-resolution (UHR) optical coherence tomography (OCT).Full Text Available

UK PubMed Central (United Kingdom)

Purpose.To investigate the characteristics of a spectral-domain optical coherence tomography (SD-OCT) image phenomenon known as the mirror artifact, calculate its prevalence, analyze...Full Text Available

UK PubMed Central (United Kingdom)

We present a method to make phantoms of coronary arteries for intravascular optical coherence tomography (IV-OCT). The phantoms provide a calibrated OCT response similar to the layered structure of...Full Text Available

International Nuclear Information System (INIS)

We present a simple protocol to purify a coherent-state superposition that has undergone a linear lossy channel. The scheme constitutes only a single beam splitter and a homodyne detector, and thus is experimentally feasible. In practice, a superposition of coherent states is transformed into a classical mixture of coherent states by linear loss, which is usually the dominant decoherence mechanism in optical systems. We also address the possibility of producing a larger amplitude superposition state from decohered states, and show that in most cases the decoherence of the states are amplified along with the amplitude.

Science.gov (United States)

... and flashtube. Unfortunately, we had insufficient laser intensity to use the harmonic from a KDP crystal as a monitor. This ...

CERN Document Server

We report an observation of a delayed all-optical routing/switching phenomenon based on ultraslow group velocity of light via nondegenerate four-wave mixing processes in a defected solid medium. Unlike previous demonstrations of enhanced four-wave mixing processes using the slow light effects, the present observation demonstrates a direct retrieval of the resonant Raman-pulse excited spin coherence into photon coherence through coherence conversion processes.

CERN Document Server

The Nystrom method is an efficient technique to speed up large-scale learning applications by generating low-rank approximations. Crucial to the performance of this technique is the assumption that a matrix can be well approximated by working exclusively with a subset of its columns. In this work we relate this assumption to the concept of matrix coherence and connect matrix coherence to the performance of the Nystrom method. Making use of related work in the compressed sensing and the matrix completion literature, we derive novel coherence-based bounds for the Nystrom method in the low-rank setting. We then present empirical results that corroborate these theoretical bounds. Finally, we present more general empirical results for the full-rank setting that convincingly demonstrate the ability of matrix coherence to measure the degree to which information can be extracted from a subset of columns.

International Nuclear Information System (INIS)

When energetic bunches of electrons traverse an undulator field, they can spontaneously emit radiation both coherently and incoherently. Although it has generally been assumed that undulator radiation is incoherent at wavelengths short compared to the longitudinal size of the electron bunch, several recent observations have proved this assumption false. Furthermore, the appearance of coherent radiation is often accompanied by a significant increase in radiated power. Here we report observations of strongly enhanced coherent spontaneous radiation together with direct measurements, using transition radiation techniques, of the electron distributions responsible for the coherent emission. We also report demonstrated enhancements in the predicted spontaneous radiated power by as much as 6x10"4 using electron bunch compression. copyright 1996 American Institute of Physics.

CERN Document Server

The problem of model selection arises in a number of contexts, such as subset selection in linear regression, estimation of structures in graphical models, and signal denoising. This paper generalizes the notion of "incoherence" in the existing literature on model selection and introduces two fundamental measures of coherence---termed as the worst-case coherence and the average coherence---among the columns of a design matrix. It utilizes these two measures of coherence to provide an in-depth analysis of two variants of a simple one-step thresholding (OST) algorithm for model selection and proves that OST is feasible for model selection as long as the design matrix obeys an easily verifiable property. One of the key insights offered by the ensuing analysis in this regard is that if the design matrix has reasonably small worst-case and average coherence then OST performs ...

International Nuclear Information System (INIS)

We investigated the Raman coherence characteristics of a solid hydrogen film deposited on a sapphire substrate held at 5.3 K. Using Raman coherence prepared with two single-frequency pulsed lasers, we generated the multiorder coherent Raman sidebands in solid hydrogen film. The highorder Raman sidebands were obtained under strong pumping intensities (? 230 MW/cm2). The generated anti-Stokes(AS)-Raman sidebands extend from the ultraviolet (292 nm for the AS5 band) to the visible (565 nm for the AS1 band) region. The multiorder Raman sideband generation is found to be due to the parametric coupling of pump and coupling lasers. The frequency conversion efficiency from pumping beams to the first AS-Raman sideband shows a maximum (14 %) at a pumping intensity of 360 MW/cm2. From an experiment that makes the multimode probe beam beat with the prepared Raman coherence, we found that the prepared Raman ...

Energy Technology Data Exchange (ETDEWEB)

Bremsstrahlung emitted in the {alpha}+p reaction at 50 MeV/nucleon was studied using a 200 MeV {alpha}-particle beam and a liquid hydrogen target. Double-differential photon cross sections were measured over a wide range of angles and energies. Coherent bremsstrahlung was found to be strong for all photon energies. The cross section is enhanced at the highest photon energies and is characteristic of direct capture to the unbound {sup 5}Li ground and first excited state. With direct capture as a limiting case of coherent bremsstrahlung a consistent reaction picture can be obtained.

CERN Document Server

The coherent $\\omega$-meson photoproduction from nuclei is proposed as a phenomenological method to evaluate the momentum dependence of $\\omega$-meson mass shift and width in nuclear matter. We analyze available data on un-separated coherent and incoherent $\\omega$-meson photoproduction from nuclei and extract the imaginary part of the the complex forward $\\omega{N}$ scattering amplitude, which is proportional to the in-medium $\\omega$-meson width. The accuracy of the currently available data is not sufficient to evaluate the real part of forward $\\omega{N}$ scattering amplitude and reconstruct the momentum dependence of the mass shift of the $\\omega$-meson.

Science.gov (United States)

For coupled quantum wires and dots, tunneling effects and coherent transport for quantum computing are being studied. In 2D systems, electron-hole bilayers for exciton...

UK PubMed Central (United Kingdom)

Absolute measurements of cerebral blood flow (CBF) are an important endpoint in studies of cerebral pathophysiology. Currently no accepted method exists for in vivo longitudinal...Full Text Available

Science.gov (United States)

... of Dist SpeA tI/ __LLL5' Page 5. 3 the coherent effects on the spontaneous radiation, we calculate the pump- field-induced ...

Science.gov (United States)

Electrically triggered action potentials in the giant alga Chara corallina are associated with a transient rise in the concentration of free Ca(2)+ in the cytoplasm (Ca(2)+(cyt)). The present measurements of Ca(2)+(cyt) during membrane excitation show that stimulating pulses of low magnitude (subthreshold pulse) had no perceivable effect on Ca(2)+(cyt). When the strength of a pulse exceeded a narrow threshold (suprathreshold pulse) it evoked the full extent of the Ca(2)+(cyt) elevation. This suggests an all-or-none mechanism for Ca(2)+ mobilization. A transient calcium rise could also be induced by one subthreshold pulse if it was after another subthreshold pulse of the same kind after a suitable interval, i.e., not closer than a few 100 ms and not longer than a few seconds. This dependency of Ca(2)+ mobilization on single and double pulses can be simulated by a model in which a second messenger is produced in a voltage-dependent manner. This ...

International Nuclear Information System (INIS)

New non-collinear schemes are suggested for transverse velocity modulation of electron beams and for the generation of coherent spontaneous radiation by these transversely modulated beams. It is shown that due to the non-collinearity some orders of magnitude enhancement can be achieved for the coherent spontaneous radiation (CSR) power at both the fundamental and harmonic frequencies.

UK PubMed Central (United Kingdom)

Mechanisms underlying the release of paclitaxel (PTX) from poly(ethylene glycol)/poly(lactic-co-glycolic acid) (PEG/PLGA) blends were investigated by coherent anti-Stokes Raman scattering (CARS)...Full Text Available

International Nuclear Information System (INIS)

An analytic solution is obtained for the equations of resonance coherent SRS by neglecting the population of the final level of the Raman transition for the systems with the active-medium length that is smaller than the wavelength of the incident light. For the extended systems, a numerical solution is obtained. The energy distribution of the Stokes pulses is found. The large-scale (about 100%) fluctuations of the Stokes radiation energy were observed in the case of unsaturated amplified spontaneous emission. (nonlinear optical phenomena)

Energy Technology Data Exchange (ETDEWEB)

Visual excitation is initiated by the absorption of a photon by the 11-cis retinal chromophore bound within the pigment called rhodopsin. We have used a variety of vibrational spectroscopies to obtain information about the vibrational nuclear dynamics that lead to this efficient photochemical isomerization. The cis-trans isomerization in rhodopsin is complete in only 200 fs. The extreme speed of this process, which is consistent with the {approximately}50 fs lifetime indicated by the spontaneous emission yield, suggests that the photochemistry involves non-stationary states or vibrational coherence. Recent studies have in fact observed vibrationally coherent oscillations of the ground state photoproduct called bathorhodopsin following impulsive excitation of the rhodopsin reactant. This conclusively demonstrates that the isomerization process in rhodopsin is vibrationally coherent. These observations further suggest that ...

CERN Document Server

We report measurements for coherent rho^0 production, AuAu->AuAu rho^0, and coherent rho^0 and e^+e^- pair production accompanied by mutual nuclear Coulomb excitation, AuAu->Au*Au* rho^0 and AuAuee, in ultra-peripheral relativistic gold-gold collisions (UPC). We discuss transverse momentum, mass, and rapidity distributions. The two photon-process of e^+e^- pair production is an important probe of strong field QED because of the large coupling Z*alpha=0.6. At sqrt{s}=200GeV, the e^+e^- production cross section agrees with lowest order QED calculations. The cross sections for coherent rho^0 production at sqrt{s}=130 and 200GeV are in agreement with theoretical predictions. The calculations for both, coherent e^+e^- and rho^0 production treat nuclear excitation as independent process.

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Mood in humans is a complex phenomenon that integrates emotion (e.g. happiness and sadness), cognition, perception, ideation, and action in a coherent manner. In bipolar disorder extremes of mood (up or down) occur outside the normal range, in which all the above functions are coherently affected. Mood is controlled by a series of separate but interactive brain circuits that involve much of the brain, but particularly the limbic system. The question addressed in this paper is whether the coordination of all these separate systems into one coherent functional mood is mediated by non-linear dynamics acting between these systems as equal participants; or whether it is affected by a single master regulator controlling the others. The possible roles, as master regulators, of non-linear dynamica...

CERN Document Server

Analysis of the dynamics of the cavity radiation of a coherently pumped correlated emission laser is presented. The phase fluctuation and dephasing are found to affect the time evolution of the two-mode squeezing and intensity of the cavity radiation significantly. The intensity and degree of the two-mode squeezing increase at early stages of the process with time, but this trend changes rapidly afterwards. It is also shown that they increase with phase fluctuation and dephasing in the strong driving limit, however the situation appears to be opposite in the weak driving limit. This essentially suggests that the phase fluctuation and dephasing weaken the coherence induced by a strong driving mechanism so that the spontaneous emission gets a chance. The other important aspect of the phase fluctuation, in this regard, is the relaxation of the time at which the maximum squeezing is manifested as well as the time in which the radiation remains in a ...

Energy Technology Data Exchange (ETDEWEB)

An electronically controllable apparatus is described which modulates a continuous wave laser beam so as to produce an output beam consisting of coherent ''pulses'' that are electronically controllable as to both pulse repetition rate and pulse width. The apparatus includes two acoustic devices positioned so that the laser beam passes through them in sequence, and apparatus or for passing sound waves through the devices to frequency shift the laser radiation as well as to diffract it. Each acoustic device such as generates sound waves containing a group of frequencies which result in spaced pulses. The spreading of a laser beam at which emanates from the first acoustic device is countered by the second acoustic device to produce a collimated, coherently pulsed, laser beam.

Energy Technology Data Exchange (ETDEWEB)

Investigations of superdense compression touch on such problems as ultrahigh-frequency oscillations of matter in the generation of gravitational waves, the powerful pumping of hard coherent radiation, and the laboratory simulation of stellar interiors. This paper reviews the theory of supercompression and discusses some experiments involving multifoil collision supercompression.

UK PubMed Central (United Kingdom)

A major goal in perceptual neuroscience is to understand how signals from different sensory modalities are combined to produce stable and coherent representations. We previously investigated interactions...Full Text Available

UK PubMed Central (United Kingdom)

In this study, we investigated on a systems level how complex protein interactions underlying cell polarity in yeast determine the dynamic association of proteins with the polar cortical domain (PCD)...Full Text Available

UK PubMed Central (United Kingdom)

Photosynthetic antenna complexes capture and concentrate solar radiation by transferring the excitation to the reaction center that stores energy from the photon in chemical bonds. This process occurs...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundNew technology allows more precise definition of structural alterations of all retinal layers although it has not been used previously in cases of optic...Full Text Available

UK PubMed Central (United Kingdom)

This article addresses the problem of how to ensure consistency in messages communicating public health recommendations on environmental health and on child health. The World Health Organization states...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Algebraic properties of the analytical model, describing electro-magnetic weak interaction with the two-level system with two-fold degenerate state are considered. The expressions for the coherent states and Green function of the system are obtained.

International Nuclear Information System (INIS)

A new kind of e-beam bunching enabling the production of coherent spontaneous emission (CSE) is proposed and considered. It is shown that an e-beam in passing through an undulator will induce CSE along with incoherent spontaneous radiation on the same wavelength if the e-beam transverse velocity is modulated with a spatial period twice as long as the radiation wavelength. Such angular modulated beams can be regarded as alternatives to conventionally density modulated beams for CSE production. Requirements for e-beams are similar in both cases.

International Nuclear Information System (INIS)

A ''coherent flucton'' nuclear model is proposed which provides for new possibilities for particle scattering studies on nuclei. It is based on the data of nuclear matter density distribution and is used for calculating the ground state energy of Fermi system terminals. The ''coherent flucton'' model is applied to the distribution of 1 GeV protons on "2"8Si, "3"2S, "4"0Ca, "4"8Ca, "5"8Ni, "2"0"8Pb nuclei. The calculations by the model agree well with experimental data.

British Library Electronic Table of Contents (United Kingdom)

Epitaxial thin films of nanotwinned face-centered cubic metals such as Cu possess an unprecedented combination of high hardness and high electrical conductivity due to the unique structure of nanometer-spaced coherent twin boundaries. Recent studies of in-situ nanoindentation in a transmission electron microscope have provided new insights on the deformation behavior of nanotwins that are reviewed here. In particular, two unit processes are highlighted: first, stress-induced migration of ?3 {112} incoherent twin boundary that leads to de-twinning of nanotwins; second, twinning dislocation can be multiplied at ?3 {111} coherent twin boundary.

Science.gov (United States)

We outline the process for determining the morphology of subsurface epithelial cell nuclei using depth-resolved light scattering measurements. The measurements are accomplished using a second generation angle-resolved low coherence interferometry system. The new system greatly improves data acquisition and analysis times compared to the initial prototype system. The calibration of the new system is demonstrated in scattering studies to determine the size distribution of polystyrene microspheres in a turbid sample. The process for determining the size of cell nuclei is discussed by analyzing measurements of basal cells in a sub-surface layer of intact, unstained epithelial tissue.

Energy Technology Data Exchange (ETDEWEB)

Objectives: To investigate optical coherence tomography consistency on foveal thickness, foveal volume, and macular volume measurements in patients with and without diffuse diabetic macular edema. Introduction: Optical coherence tomography represents an objective technique that provides cross-sectional tomographs of retinal structure in vivo. However, it is expected that poor fixation ability, as seen in diabetic macular edema, could alter its results. Several authors have discussed the reproducibility of optical coherence tomography, but only a few have addressed the topic with respect to diabetic maculopathy. Methods: The study recruited diabetic patients without clinically evident retinopathy (control group) and with diffuse macular edema (case group). Only one eye of each patient was evaluated. Five consecutive fast macular scans were taken using Ocular Coherence Tomography 3; the 6 mm macular map ...

Energy Technology Data Exchange (ETDEWEB)

The Linac Coherent Light Source (LCLS) is required to deliver a high quality electron beam for producing coherent X-rays. As a result, high resolution beam position monitoring is required. The Beam Position Monitor (BPM) digitizer acquires analog signals from the beam line and digitizes them to obtain beam position data. Although Matlab is currently being used to test the BPM digitizer?s functions and capability, the Controls Department at SLAC prefers to use Experimental Physics and Industrial Control Systems (EPICS). This paper discusses the transition of providing similar as well as enhanced functionalities, than those offered by Matlab, to test the digitizer. Altogether, the improved test stand development system can perform mathematical and statistical calculations with the waveform signals acquired from the digitizer and compute the fast Fourier transform (FFT) of the signals. Finally, logging of meaningful data into files has been added.

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Purpose: To describe the clinical aspects and evaluate optical coherence tomography of macular microholes. Methods: Seven patients were assessed (8 eyes) with microholes of the macula. All patients underwent complete eye examination, fundus photography, fluorescent angiography and OCT-3 imaging. Results: Ages ranged from 26 to 69 years. Six patients were female (85.7%) and five of them had microhole in the right eye. The presenting symptom was decrease in visual acuity (71.3%) and central scotoma in (14.3%). Five eyes (71.4%) had no defects shown by fluorescent angiography. A defect in the outer retina was demonstrated in all eyes on optical coherence tomography. The lesions were nonprogressive. Conclusion: Macular microholes are small lamellar defects in the outer retina. The condition is nonprogressive, generally unilateral and compatible with good visual acuity. Fundus biomicroscopy associated with an optical coherence ...

British Library Electronic Table of Contents (United Kingdom)

Abstract In this paper, the effect of several turbulence parameters during various flow conditions in Owens Valley, educed from coherent Doppler lidar data have been studied. Radial velocity structure functions are processed to estimate the turbulent kinetic energy (TKE) dissipation rate, integral length scale and velocity variance, assuming a theoretical model for isotropic wind fields. Corrections for turbulence measurements have been considered to address the complications due to inherent volumetric averaging of radial velocity over each range gate, noise of the lidar data, and the assumptions required to estimate effects of smaller scales of motion on turbulence quantities. Using data from the Terrain-induced Rotor Experiment (T-REX) in April-May 2006, vertical profiles of wind and tur...

Science.gov (United States)

The excess energy of several III-V and II-VI strained-layer semiconductor superlattices ({ital AC}){sub {ital p}}(BC){sub p} is studied as a function of the repeat period {ital p} and orientation {bold G}=(001), (110), (111), and (201), using first-principles calculations. We discover a number of universal features, including the predicted instability for nearly all {ital p}'s and {bold G}'s with respect to {ital bulk} disproportionation, the identification of chalcopyrite as a metastable ordered structure, and the stability of all thin {ital epitaxial} (110) and (201) and most common-anion (001) superlattices relative to coherent phase separation.

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The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL). To ensure the vitality of FEL lasing, it is critical to preserve the high quality of the electron beam during acceleration and compression. The peak current and final energy are very sensitive to system jitter. To minimize this sensitivity, a longitudinal feedback system on the bunch length and energy is required, together with other diagnostics and feedback systems (e.g., on transverse phase space). Here, we describe a simulation framework, which includes a realistic jitter model for the LCLS accelerator system, the RF acceleration, structure wakefield, and second order optics. Simulation results show that to meet the tight requirements set by the FEL, such a longitudinal feedback system is mandatory.

International Nuclear Information System (INIS)

In a seeded high-gain free-electron laser (FEL), where a coherent laser pulse interacts with an ultrarelativistic electron beam, the seed laser pulse can be frequency chirped, and the electron beam can be energy chirped. Besides these two chirps, the FEL interaction introduces an intrinsic frequency chirp in the FEL even if the above-mentioned two chirps are absent. We examine the interplay of these three chirps. The problem is formulated as an initial value problem and solved via a Green function approach. Besides the chirp evolution, we also give analytical expressions for the pulse duration and bandwidth of the FEL, which remains fully longitudinally coherent in the high-gain exponential growth regime. Because the chirps are normally introduced for a final compression of the FEL pulse, some conceptual issues are discussed. We show that to get a short pulse duration, an energy chirp in the electron beam is important.

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The coherent flucton model is applied to the description of some basic nuclear properties, such as: ground state energies, bond energies, nucleon momentum spectra, and nuclear density distributions. It is shown that the momentum distributions of the nucleons coincide with the Fermi distribution for small momenta and exhibit a well pronounced high energy ''tail'', thus providing inclusive reactions of pi-meson generations in kinematically forbidden areas at nucleon-nucleon collisions. Analytical expressions for the bond energy and nuclear density distribution are derived. An agreement with the experimentally obtained data is achieved. The model features are discussed referring to the processes, characterized mainly by the geometric and dynamic properties of the nuclei, as well as by nuclear density distribution. In particular, ion-ion scattering processes at high energy are considered.

International Nuclear Information System (INIS)

We obtain and investigate the regular eigenfunctions of simple differential operators xr dr+1/dxr+1, r = 1, 2, ..., with the eigenvalues equal to 1. With the help of these eigenfunctions, we construct a non-unitary analogue of a boson displacement operator which will be acting on the vacuum. In this way, we generate collective quantum states of the Fock space which are normalized and equipped with the resolution of unity with the positive weight functions that we obtain explicitly. These states are thus coherent states in the sense of Klauder. They span the truncated Fock space without first r lowest-lying basis states: |0), |1), ..., |r - 1). These states are squeezed, sub-Poissonian in nature and reminiscent of photon-added states in Agarwal and Tara (1991 Phys. Rev. A 43 492).

Energy Technology Data Exchange (ETDEWEB)

We propose and analyze a novel regenerative amplifier free electron laser (FEL) to produce fully coherent x-ray pulses. The method makes use of narrow-bandwidth Bragg crystals to form an x-ray feedback loop around a relatively short undulator. Self-amplified spontaneous emission (SASE) from the leading electron bunch in a bunch train is spectrally filtered by the Bragg reflectors and is brought back to the beginning of the undulator to interact repeatedly with subsequent bunches in the bunch train. The FEL interaction with these short bunches not only amplifies the radiation intensity but also broadens its spectrum, allowing for effective transmission of the x-rays outside the crystal bandwidth. The spectral brightness of these x-ray pulses is about two to three orders of magnitude higher than that from a single-pass SASE FEL.

International Nuclear Information System (INIS)

Coherent Smith-Purcell radiation, emitted from short-bunched electrons passing by a lamellar-type grating of aluminum, has been observed in the millimeter wave region. The energy of the electrons is either 42 MeV when they are accelerated by an L-band linear accelerator or 150 MeV accelerated by an S-band one. The intensity of the radiation is proportional to the square of the beam current. The radiation is linearly polarized, and the electric vector of the radiation is in the plane defined by the observing point and the beam trajectory. The intensity decreases with the beam height, i.e. the distance of the beam from the surface of the grating, in accordance with the modified Bessel function of zeroth order. copyright 1996 American Institute of Physics.

CERN Document Server

We present a single solid-state laser system to cool, coherently manipulate and detect $^{25}$Mg$^+$ ions. Coherent manipulation is accomplished by coupling two hyperfine ground state levels using a pair of far-detuned Raman laser beams. Resonant light for Doppler cooling and detection is derived from the same laser source by means of an electro-optic modulator, generating a sideband which is resonant with the atomic transition. We demonstrate ground-state cooling of one of the vibrational modes of the ion in the trap using resolved-sideband cooling. The cooling performance is studied and discussed by observing the temporal evolution of Raman-stimulated sideband transitions. The setup is a major simplification over existing state-of-the-art systems, typically involving up to three separate laser sources.

International Nuclear Information System (INIS)

The method of inversion of the eigenvalue problem previously developped for nuclei with axial symmetry is extended to asymmetric equilibrium shapes. This new approach to the asymmetric rotator model is applied to the odd-mass Iridium isotopes. A satisfactory and coherent description of the observed energy spectra is obtained, especially for the lighter isotopes. (orig.).

Energy Technology Data Exchange (ETDEWEB)

Microscopic non-energy weighted sum-rules for the total rates of the neutrinoless ..mu..-e conversion process are constructed in the frame of the shell model for closed shell nuclei. For non-closed shell nuclei the relevant rates were obtained by interpolation. Also the contribution of the coherent process to the total ..mu..-e conversion rate is calculated and discussed.

International Nuclear Information System (INIS)

We report the homodyne detection of phase modulation sidebands induced on a laser beam by a coherently bunched electron beam. This provides a sensitive and nonperturbing measurement of complex Fourier time series components of the electron density. A proof-of-principle measurement of the microwave frequency component of electron density in a crossed-field device, which agrees well with a calculation of the same quantity, is reported.

International Nuclear Information System (INIS)

This review briefly describes current efforts to develop superradiant sources of coherent radiation for the sub-nanometer range of wavelenghs, using nuclear rather than the atomic or molecular transitions that are stimulated in existing lasers. First the radiative (including Raman) interactions of nuclei with those of atoms and molecules are compared; then the present status of research on the fundamental problems involved in stimulating nuclear gamma radiation is described. (author). 20 refs.; 2 figs.

Science.gov (United States)

Spike-timing-dependent plasticity (STDP), a form of Hebbian plasticity, is inherently stabilizing. Whether and how GABAergic inhibition influences STDP is not well understood. Using a model neuron driven by converging inputs modifiable by STDP, we determined that a sufficient level of inhibition was critical to ensure that temporal coherence (correlation among presynaptic spike times) of synaptic inputs, rather than initial strength or number of inputs within a pathway, controlled postsynaptic spike timing. Inhibition exerted this effect by preferentially reducing synaptic efficacy, the ability of inputs to evoke postsynaptic action potentials, of the less coherent inputs. In visual cortical slices, inhibition potently reduced synaptic efficacy at ages during but not before the critical period of ocular dominance (OD) plasticity. Whole-cell recordings revealed that the amplitude of unitary IPSCs from parvalbumin positive (Pv+) interneurons to ...

British Library Electronic Table of Contents (United Kingdom)

Abstract This article advocates that some form of personal immortality is not only taught in F.D.E. Schleiermacher's Glaubenslehre but is also necessary for the coherence of the same work. The combination of a naturalized account of redemption, a commitment to universal salvation and the realist observation that some never know Christ in this life causes Schleiermacher to posit a certain but content-free afterlife to account for the discrepancy.

International Nuclear Information System (INIS)

This paper discusses the concept of controllable subspace for open quantum dynamical systems. It is constructively demonstrated that combining structural features of decoherence-free subspaces with the ability to perform open-loop coherent control on open quantum systems will allow decoherence-free subspaces to be controllable. This is in contrast to the observation that open quantum dynamical systems are not open-loop controllable. To a certain extent, this paper gives an alternative control theoretical interpretation on why decoherence-free subspaces can be useful for quantum computation.

International Nuclear Information System (INIS)

The subject of quantum optics has undergone considerable development in the last twenty-five years. Spurred by the invention of the laser, the theoretical understanding of the coherence and statistical properties of optical beams has now attained a stage of maturity where it is possible to treat different kinds of light sources. Over approximately the latter half of this period of development in quantum optics, the free-electron laser (FEL) has been developed to the point where it is now regarded as a tunable light source of considerable versatility, with prospects of producing radiation over a wide range of wavelengths at large levels of power. Since the basic mechanism for radiation gain in an FEL can be understood in classical terms, much of the literature on the subject does not need to venture outside the domain of classical physics. However, it is natural that the coherence and statistical properties of photon beams produced by FEL's ...

CERN Document Server

The mean-field pictures based on the standard time-dependent variational approach have widely been used in the study of nonlinear many-boson systems such as the Bose-Hubbard model. The mean-field schemes relevant to Gutzwiller-like trial states $|F>$, number-preserving states $|\\xi >$ and Glauber-like trial states $|Z>$ are compared to evidence the specific properties of such schemes. After deriving the Hamiltonian picture relevant to $|Z>$ from that based on $|F>$, the latter is shown to exhibit a Poisson algebra equipped with a Weyl-Heisenberg subalgebra which preludes to the $|Z>$-based picture. Then states $|Z>$ are shown to be a superposition of $\\cal N$-boson states $|\\xi>$ and the similarities/differences of the $|Z>$-based and $|\\xi>$-based pictures are discussed. Finally, after proving that the simple, symmetric state $|\\xi>$ indeed corresponds to a SU(M) coherent state, a dual version of states $|Z>$ and ...

International Nuclear Information System (INIS)

Particularly high coherence of the x-ray beam is associated, on the ID19 beamline at ESRF, with the small angular size of the source as seen from a point of the sample (0.1-1 #mu#rad). This feature makes the imaging of phase objects extremely simple, by using a 'propagation' technique. The physical principle involved is Fresnel diffraction. Phase imaging is being simultaneously developed as a technique and used as a tool to investigate light natural or artificial materials introducing phase variations across the transmitted x-ray beam. They include polymers, wood, crystals, alloys, composites or ceramics, exhibiting inclusions, holes, cracks, ... . 'Tomographic' three-dimensional reconstruction can be performed with a filtered back-projection algorithm either on the images processed as in attenuation tomography, or on the phase maps retrieved from the images with a reconstruction procedure similar to that used for electron microscopy. The combination of diffraction ...

International Nuclear Information System (INIS)

We describe a camera to record coherent scattering patterns with a soft-x-ray free-electron laser (FEL). The camera consists of a laterally graded multilayer mirror, which reflects the diffraction pattern onto a CCD detector. The mirror acts as a bandpass filter for both the wavelength and the angle, which isolates the desired scattering pattern from nonsample scattering or incoherent emission from the sample. The mirror also solves the particular problem of the extreme intensity of the FEL pulses, which are focused to greater than 10"1"4 W/cm"2. The strong undiffracted pulse passes through a hole in the mirror and propagates onto a beam dump at a distance behind the instrument rather than interacting with a beam stop placed near the CCD. The camera concept is extendable for the full range of the fundamental wavelength of the free electron laser in Hamburg (FLASH) FEL (i.e., between 6 and 60 nm) and into the water window. We have fabricated and tested various ...

International Nuclear Information System (INIS)

There is growing interest in the generation and characterization of femtosecond and subfemtosecond pulses from linac-based free-electron lasers (FELs). In this report, following the method of Ricci and Smith (Phys. Rev. ST Accel. Beams 3, 032801 (2000)), we investigate the measurement of the longitudinal bunch profile of an ultrashort electron bunch produced by these FELs. We show that this method can be applied in a straightforward manner at x-ray FEL facilities such as the Linac Coherent Light Source by slightly adjusting the second bunch compressor followed by running the bunch on an rf zero-crossing phase of the final linac. We find that the linac wakefield strongly perturbs the measurement, and through analysis show that it can be compensated in a simple way. We demonstrate the effectiveness of this method and wakefield compensation through numerical simulations, including effects of coherent synchrotron radiation and longitudinal space ...

International Nuclear Information System (INIS)

The 1.04 GeV-proton elastic scattering from "4"0Ca is studied in the framework of the coherent density fluctuation model (CDFM). The calculations are carried out in the Glauber theoretical scheme with three different charge densities. It is shown that: i) the account of the flucton correlations leads to results considerably different from those obtained in the independent particle Glauber approach (IPGA); ii) in contrast to the case of IPGA the use of a more realistic density improves the agreement of CDPM-results with the experimental data. (orig.).

Science.gov (United States)

The phase space beam analyzer is a measurement instrument that is applied in laser technology to perform analyses of the spatial and angular distribution of rays. We are interested in this instrument as a means to characterize non-coherent light sources. In this context, a closer look at the tolerances of this optical instrument was considered useful. Having a so-called quadrupole lens as a key element, the phase space beam analyzer is a device that features anamorphic optical properties. To describe these anamorphic properties, recurrence was made to a description by extended ray-transfer matrices. This formalism allows for an analysis of the alignment tolerances of the phase space beam analyzer and facilitates a study of the sensitivities of the instrument. The analysis is complemented using numerical ray tracing.

Energy Technology Data Exchange (ETDEWEB)

The relaxation oscillation of the amplified spontaneous radiation pulses emitted from a single-mirror Cu/CuBr laser has been observed for the first time and the experimental characteristics of the relaxation oscillation were obtained. In addition, the spatial and temporal distributions of the light pulse intensity of the amplified spontaneous radiation were also measured and found to be comparatively and uniform. The spatial coherence of the amplified spontaneous radiation was found to be better than that of the laser with the same lasant.

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Recent experimental results indicate a dominance of fundamental NN..-->..NN..pi.. processes in near-threshold nuclear pion production. Such two-nucleon processes are revealed in part by distinct polarization effects characterizing both weak (ground state) and strong, highly selective, maximal J coupling transitions for the (p,..pi../sup -/) reaction. For (p,..pi../sup +/), where several NN processes can contribute coherently, analyzing power data suggest a means of distinguishing the contributions from different fundamental NN..-->..NN..pi.. isospin channels.

CERN Document Server

Constrained quantum dynamics is used to propose a nonlinear dynamical equation for pure states of a generalized coarse-grained system. The relevant constraint is given either by the generalized purity or by the generalized invariant fluctuation, and the coarse-grained pure states correspond to the generalized coherent i.e. generalized nonentangled states. Open system model of the coarse-graining is discussed. It is shown that in this model and in the weak coupling limit the constrained dynamical equations coincide with an equation for pointer states, based on Hilbert-Schmidt distance, that was previously suggested in the context of the decoherence theory.

Energy Technology Data Exchange (ETDEWEB)

In the early days of Moessbauer spectroscopy, it was demonstrated that coherent scattering of photons emitted by a Moessbauer source can be observed. In spite of the fact that scattering experiments could give information not accessible by the absorption method, they are not widely used. The reasons for this are, on the one hand, experimental difficulties, and on the other hand, the form of the samples, which should be large single crystals in most cases. In this work, we present a Moessbauer diffraction measurement on polycrystalline bcc iron where these problems have been overcome. We demonstrate that using the kinematical theory of gamma-ray diffraction, useful information on the relative orientation of the crystallographic axis to the hyperfine field directions can be subtracted. (orig.)

Energy Technology Data Exchange (ETDEWEB)

High-T/sub c/ superconductivity is due to the action of two mechanisms: (1) plasmon mechanism, i.e., exchange of two-dimensional (2-D) plasmons and (2) strong electron--phonon coupling. The low dimensionality and the small value of the carrier concentration make the plasmon mechanism favorable. The small value of the coherence length leads to a unique opportunity to observe a multigap structure. The proximity effect can be used in order to increase T/sub c/ of A-15 compounds.

Energy Technology Data Exchange (ETDEWEB)

The characteristics of the temperature dependence of the upper critical magnetic field, Hc2(T), of structurally inhomogeneous superconductors (e.g., ternary molybdenum chalcogenides, A-15 compounds, transition metal alloys, and amorphous films) are investigated analytically. The MWGH equation for Hc2(T) is generalized to the case of weakly inhomogeneous systems with a characteristic inhomogeneity scale much smaller than the effective coherence length. It is shown that an increase in the dispersion of the diffusion coefficient leads to an increase in the slope and width of the linear section of the Hc2(T) curve. 11 references.

International Nuclear Information System (INIS)

Coherent x-ray production by a seeded free electron laser (FEL) is important for next generation synchrotron light sources. The authors examine the feasibility and features of FEL emission seeded by a high-order harmonic generation (HHG) of an infrared laser. In addition to the intrinsic FEL chirp, the longitudinal profile and spectral bandwidth of the HHG seed are modified significantly by the FEL interaction well before saturation. This smears out the original attosecond pulselet structure. The authors introduce criteria for this smearing effect on the pulselet and the stretching effect on the entire pulse. They discuss the noise issue in such a seeded FEL.

Energy Technology Data Exchange (ETDEWEB)

Energy conservation presents major opportunities to industry, both to improve its energy efficiency (hence its competitiveness and profitability) and to supply services and equipment. There are vast markets, both in the United Kingdom and overseas, but there are also barriers. There is reluctance on one hand to make new investment on the scale required. On the other hand, the problems of meeting a fragmented new demand are complicated by the fragmentation of the conservation supply industry. This calls for a new coherent, and innovative approach by both the conservation supply industry and the financial institutions. 3 tables.

Energy Technology Data Exchange (ETDEWEB)

In this paper we report on multi-physics, multi-billion macroparticle simulation of beam transport in a free electron laser (FEL) linac for future light source applications. The simulation includes a self-consistent calculation of 3D space-charge effects, short-range geometry wakefields, longitudinal coherent synchrotron radiation (CSR) wakefields, and detailed modeling of RF acceleration and focusing. We discuss the need for and the challenges associated with such large-scale simulation. Applications to the study of the microbunching instability in an FEL linac are also presented.

International Nuclear Information System (INIS)

Total photon attenuation coefficients near absorption edges are determined in certain suitable elements and compounds. Photoelectric cross sections for elements are deduced from these by subtracting the coherent and incoherent scattering cross sections as well as other elemental cross sections in the cases of compounds. Certain deviations are observed on comparison with the available theoretical and experimental compilations. The I/sub L//sub #alpha#//Il x-ray intensity ratio measured by photon excitation near threshold is found to agree better with the theory than the other available experimental data.

Energy Technology Data Exchange (ETDEWEB)

The proposed short wavelength coherent light source driven by the SLAC 3 km linac might be used to induce transitions between nuclear isomeric states. If an isotope were found with energetically adjacent isomeric states, one short-lived and one long-lived, and it were possible to separate and concentrate the long-lived species, and other nuclear and solid-state parameters were favorable, it might be possible to convert sufficient population to the short-lived state to realize {gamma}-ray lasing. Even if the x-ray intensity were insufficient, study of such driven transitions would be quite valuable.

International Nuclear Information System (INIS)

Ab initio total-energy calculations, based on the exact muffin-tin orbital method, are used to determine the elastic properties of Pd1-xAgx random alloys in the face-centered-cubic crystallographic phase. The compositional disorder is treated within the coherent-potential approximation. The single crystal and polycrystalline elastic constants and the Debye temperature are calculated for the whole range of concentration, 0?x?1. It is shown that the variation in the elastic parameters of Pd-Ag alloys with chemical composition strongly deviates from a simple linear or parabolic trend. The complex electronic origin of these anomalies is demonstrated.

International Nuclear Information System (INIS)

The TESLA Test Facility (TTF) at DESY is a facility producing sub-picosecond electron pulses for the generation of VUV or soft X-ray radiation in a free electron laser (FEL). The same electron pulses would also allow the direct production of high-power coherent radiation by passing the electron beam through an undulator. Intense, coherent far-infrared (FIR) undulator radiation can be produced from electron bunches at wavelengths longer than or equal to the bunch length. The source described in this paper provides, in the wavelength range 50-300 #mu#m, a train of about 1-10 ps long radiation pulses, with about 1 mJ of optical energy per pulse radiated into the central cone. The average output power can exceed 50 W. In this conceptual design, we intend to use a conventional electromagnetic undulator with a 60 cm period length and a maximum field of 1.5 T. The FIR source will use the spent electron beam coming from the VUV FEL which allows one to ...

Energy Technology Data Exchange (ETDEWEB)

An analysis was perfonned on the mid-latitude scintillation and coherence frequency bandwidth (Fcoh) using transionospheric VHF signal data. The data include 1062 events spanning from November 1997 to June 2002. Each event records FORTE satellite received VHF signals from LAPP located at Los Alamos, New Mexico. Fcohs were derived to study scintillation characteristics on diurnal and seasonal variations, as well as changes due to solar and geomagnetic activities. Comparisons to the VHFIUHF coherence frequency bandwidth studies previously reported at equatorial and mid-latitude regions are made using a 4th power frequency dependence relationship. Furthennore, a wideband ionospheric scintillation model, WBMOD, was used to estimate Fcohs and compared with our VHF Fcoh values. Our analysis indicates mid-latitude scintillation characteristics that are not previously revealed. At the VHF bottom frequency range (3035 MHz), distinguished smaller Fcohs ...

International Nuclear Information System (INIS)

Using a noneikonal expression for the two-body scattering amplitude, consistent with the proton-nucleon scattering data, the cross-section of the 1.04 GeV-proton elastic scattering on "4"0Ca is calculated by the Glauber-Sitenko theoretical scheme in the framework of the coherent density fluctuation model (CDFM) as well as of the independent-particle model (IPM). It is shown that the use of the noneikonal amplitude in the CDFM calculations improves the agreement with the experimental data especially at larger scattering angles in contrast to the case of the independent-particle model. To that end a decisive role play the zero-motion flucton correlations taken into account in the CDFM. (orig.).

Energy Technology Data Exchange (ETDEWEB)

Our investigation concerns the class of Josephson-like systems, sharing the same nonlinear Hamiltonian. Among the latter a Josephson junction with an external biasing circuit is considered. We diagonalize the fully nonlinear Hamiltonian (in the superconductive regime of the junction) in the Fock space of the TBHA (two-boson Heisenberg algebra) and prove that such algebra leads quite naturally to the theoretical realization of codewords and logical operators: the codewords are defined as the even and odd coherent states of the TBHA, while the logical operators are expressed in terms of operators in the same algebra. Our theoretical construction corresponds to a continuous variable quantum computation scheme; the continuous variables are identified in terms of the physical operators of the junction. The link between this scheme and the technique of fermionization of bosonic systems is also discussed.

CERN Document Server

We formulate a complete theory of Edge Radiation based on a novel method relying on Fourier Optics techniques. Similar types of radiation like Transition Undulator Radiation are addressed in the framework of the same formalism. Special attention is payed in discussing the validity of approximations upon which the theory is built. Our study makes consistent use of both similarity techniques and comparisons with numerical results from simulation. We discuss both near and far zone. Physical understanding of many asymptotes is discussed. Based on the solution of the field equation with a tensor Green's function technique, we also discuss an analytical model to describe the presence of a vacuum chamber. In particular, explicit calculations for a circular vacuum chamber are reported. Finally, we consider the use of Edge Radiation as a tool for electron beam diagnostics. We discuss Coherent Edge Radiation, Extraction of Edge Radiation by a mirror, and other issues ...

International Nuclear Information System (INIS)

We present the design of a diagnostic system to measure electron cyclotron absorption at the second harmonic E-mode resonance in the JET pumped divertor plasma. The diagnostic will measure transmission as a function of frequency along one or more sightlines from which the spatial profile of the n_eT_e product will be deduced. The divertor is briefly described, and the electron cyclotron resonance physics relevant to this measurement is reviewed. The problems of measuring transmission using an oversized transmission system are discussed and the chosen measurement technique, a swept frequency interferometer using a coherent radiation source, is described. A prototype of the instrument has been assembled to test the measurement technique. Some data demonstrating the instrument's characteristics are presented. The nonresonant losses, which may affect the interpretation of the measurement, are also discussed. (orig.).

Energy Technology Data Exchange (ETDEWEB)

The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) based on the final kilometer of the Stanford Linear Accelerator. Such an FEL requires a high energy, high brightness electron beam to drive the FEL instability to saturation. When fed by an RF-photocathode gun, and modified to include two bunch compressor chicanes, the SLAC linac will provide such a high quality beam at 14 GeV and 1-{micro}m normalized emittance. In this paper, we report on recent linac studies, including beam stability and tolerances, longitudinal and transverse feedback systems, conventional and time-resolved diagnostics, and beam collimation systems. Construction and installation of the injector through first bunch compressor will be completed by December 2006, and electron commissioning is scheduled to begin in January of 2007.

Energy Technology Data Exchange (ETDEWEB)

Recently, the public has become aware of keywords like ''Quantum computer'' or ''Quantum cryptography''. Regarding their potential application in solid state based quantum information processing and their overall benefit in fundamental research quantum dots have gained more and more public interest. In this context, quantum dots are often referred to as ''artificial atoms'', a term subsuming their physical properties quite nicely and emphasizing the huge potential for further investigations. The basic mechanism to be considered is the theoretical model of a two-level system. A quantum dot itself represents this kind of system quite nicely, provided that only the presence or absence of a single exciton in the ground state of that structure is regarded. This concept can also be expanded to the presence of two excitons (bi-exciton). Transitions between the relevant levels can be ...

DEFF Research Database (Denmark)

We suggest and study designed defects in an otherwise periodic potential modulation of a two-dimensional electron gas as an alternative approach to electron spin based quantum information processing in the solid-state using conventional gate-defined quantum dots. We calculate the band structure and density of states for a periodic potential modulation, referred to as an antidot lattice, and find that localized states appear, when designed defects are introduced in the lattice. Such defect states may form the building blocks for quantum computing in a large antidot lattice, allowing for coherent electron transport between distant defect states in the lattice, and for a tunnel coupling of neighboring defect states with corresponding electrostatically controllable exchange coupling between different electron spins.

International Nuclear Information System (INIS)

Atomic ensembles, comprising clouds of atoms addressed by laser fields, provide an attractive system for both the storage of quantum information and the coherent conversion of quantum information between atomic and optical degrees of freedom. We describe a scheme for full-scale quantum computing with atomic ensembles, in which qubits are encoded in symmetric collective excitations of many atoms. We consider the most important sources of error-imperfect exciton-photon coupling and photon losses-and demonstrate that the scheme is extremely robust against these processes: the required photon emission and collection efficiency threshold is #approx#>86%. Our scheme uses similar methods to those already demonstrated experimentally in the context of quantum repeater schemes and yet has information processing capabilities far beyond those proposals.

Energy Technology Data Exchange (ETDEWEB)

Long before possible organic effects, exposure to ionizing radiations can provoke anxiety. In front of invisibility, the imagination quickly ignites. The terrorists have perfectly understood it. They are ready to use ionizing radiations as a weapon to remind traumatic images deeply rooted in people's memory. These images induce anxiety with all the clinical expressions connected to it. These symptoms require to be treated because of a possible anarchic development. For that purpose, plans have been elaborated to coordinate the different professional's actions. The coherence of medical management and communication aims to allow the most implicated people to find the way to face the events. When it is not possible, medico-psychological cells permit a specialized care. (author)

British Library Electronic Table of Contents (United Kingdom)

PurposeTo evaluate pathologic features of the photoreceptors in myopic foveoschisis with the Fourier-domain optical coherence tomography (FD-OCT).DesignObservational case series.MethodsSeventeen eyes of 15 patients with myopic foveoschisis (foveal detachment type, six eyes; foveoschisis type, 11 eyes) were included. We observed the photoreceptor inner and outer segments (IS/OS) and evaluated the morphologic status using FD-OCT. Fundus photographs and time-domain OCT (TD-OCT) images also were obtained.ResultsIS/OS defects, which are uncommon in retinal detachments in eyes with myopia, were seen clearly in five eyes (three eyes [50%] with the foveal detachment type; two eyes [18%] with the foveal schisis type). Fundus photographs showed myopic chorioretinal atrophy in eight study eyes (47%),...

International Nuclear Information System (INIS)

A photoacoustic (PA) imaging system based on an ultrasonic Fresnel zone plate (FZP) transducer is developed for the purpose of imaging biological tissue. This FZP transducer has a two-zone negative zone plate piezoelectric material pattern, and an optical fibre is integrated with the transducer on the symmetric axis of the zone plates to deliver laser pulses to the sample. The focal characteristic of the FZP transducer is analysed by theoretical prediction and experimental measurement, and the measured results are in good agreement with the predicted results. The limited-field back-projection deconvolution algorithm combined with the coherence-factor weighting technique is used to reconstruct the optical absorption distribution. The experiments were performed with phantoms and the blood vessels of chicken embryo chorioallantoic membrane. The results demonstrate that PA imaging using the FZP transducer has the ability to image biological tissue and has potential ...

International Nuclear Information System (INIS)

The dynamical decoupling (DD) aims at suppressing the decoherence by means of coherent control pulses. Even if devices exist where instantaneous pulses are an adequate approximation, experimentally a finite duration #tau#_p and a bounded amplitude are inevitable. They are the cause of additional errors which can be corrected by designing the pulse shape appropriately. The new pulse has the overall effect of an ideal, instantaneous pulse with the advantage of decoupling the spin (or qubit) from the bath up to the order O(#tau#_p"3). The limitation of the no-go theorem for #pi# pulses is avoided. Hence, the Uhrig sequence (UDD), originally thought for ideal #pi# pulses, works also for bounded control Hamiltonians. Numerical simulations show that concatenated sequences of real pulses are effective against general decoherence.

Energy Technology Data Exchange (ETDEWEB)

The detection of explosives is a notoriously difficult problem, especially at stand-off distances, due to their (generally) low vapor pressure, environmental and matrix interferences, and packaging. We are exploring optimal dynamic detection to exploit the best capabilities of recent advances in laser technology and recent discoveries in optimal shaping of laser pulses for control of molecular processes to significantly enhance the standoff detection of explosives. The core of the ODD-Ex technique is the introduction of optimally shaped laser pulses to simultaneously enhance sensitivity of explosives signatures while reducing the influence of noise and the signals from background interferents in the field (increase selectivity). These goals are being addressed by operating in an optimal nonlinear fashion, typically with a single shaped laser pulse inherently containing within it coherently locked control and probe sub-pulses. With sufficient bandwidth, the ...

Energy Technology Data Exchange (ETDEWEB)

We present sufficient conditions that imply duality for the algebras of local observables in all Abelian sectors of all locally normal, irreducible representations of a field algebra if twisted duality obtains in one of these representations. It is verified that the Yukawa/sub 2/ model satisfies these conditions, yielding the first proof of duality for the observable algebra in all coherent charge sectors in this model. This paper also constitutes the first verification of the assumptions of the axiomatic study of the structure of superselection sectors by Doplicher, Haag and Roberts in an interacting model with nontrivial sectors. The existence of normal product states for the free Fermi field algebra and, thus, the verification of the funnel property for the associated net of local algebras are demonstrated.

CERN Document Server

Solid-state single-photon sources have many desirable features that make them attractive for applications in quantum information processing. However, the phase coherence of such devices can be severely compromised by coupling to the solid-state environment. Here, we study the effects of realistic dephasing environments on a pair of solid-state single photon sources in the context of quantum interference effects such as the Hong-Ou-Mandel dip. By means of exact solutions for the non-Markovian dynamics of the sources, we show that the resulting loss of visibility depends crucially on the timing of photon detection events. Our results demonstrate that the effective visibility can be improved via temporal post-selection, and also that time-resolved interference can be a useful probe of the interaction between the emitter and its host environment.

British Library Electronic Table of Contents (United Kingdom)

MINER?A is a high resolution, fully active detector designed to study neutrino interactions on nuclei in the NuMI beam at Fermi National Accelerator Laboratory. The active volume of the detector consists of 3 tons of plastic scintillator and includes embedded targets of 4He, C, H2O, Fe and Pb. The MINER?A collaboration expects to perform precision, A-dependent neutrino cross section measurements in the 1?10 GeV region, measure the axial form factor, and study nuclear shadowing of F2, quark-hadron duality and coherent pion production, among other topics. MINER?A began data taking in the fall of 2009. This paper describes the MINER?A experiment and provides an overview of the physics objectives along with estimated uncertainties of the measurements and the tentative projected schedule of dat...

British Library Electronic Table of Contents (United Kingdom)

Perceptions of sensation and pain in healthy people are believed to be the net result of sensory input and descending modulation from brainstem and cortical regions depending on emotional and cognitive factors. Here, the influence of attention on neural activity in the spinal cord during thermal sensory stimulation of the hand was investigated with functional magnetic resonance imaging by systematically varying the participants' attention focus across and within repeated studies. Attention states included (1) attention to the stimulus by rating the sensation and (2) attention away from the stimulus by performing various mental tasks of watching a movie and identifying characters, detecting the direction of coherently moving dots within a randomly moving visual field and answering mentally-...

Energy Technology Data Exchange (ETDEWEB)

Dynamic stability enhancement of composite mode oscillations of interconnected power systems by means of a hybrid power system stabilizer is discussed here. The proposed Hybrid PSS is of a two-level structure composed of a local PSS for local mode and a global PSS for inter-area mode damping. Here, the input of the global stabilizer is the center of inertia speed deviation of slow-coherent generators. The paper is focused on the practical considerations in implementation of the proposed stabilizer. First, the optimum allocation of this stabilizer is discussed. The authors introduce an index of mode-input-assignability, by which the best sites of the stabilizer can be identified. Next, for practical applications, an estimation method for the approximation of the input of the global PSS is introduced. An approximated value of the center of inertia speed is obtained from a suitable combination of the rotor speed data of a few properly selected key generators.

International Nuclear Information System (INIS)

A beam of 3.6 MeV electrons has been used to study the generation of radiation in far infra-red (FIR) by the Smith-Purcell mechanism. The dependence of wavelength on angle of emission, over angles from 56 deg to 150 deg and wavelengths from 350 #mu#m to 1860 #mu#m, is in excellent agreement with the Smith-Purcell dispersion relation. Comparison of the yield with that from a 5000 K source suggests that the spontaneous Smith-Purcell effect offers an easily tunable alternative to the synchrotron as a coherent FIR source, and could form the basis of a cheap, compact Free Electron Laser (FEL). (author) 6 refs.; 5 figs.

Energy Technology Data Exchange (ETDEWEB)

By ab-initio calculation we show that the (Ga,Fe)N ground state may be changed from anti-ferromagnetic to ferromagnetic by acceptor defect like Ga vacancies. The electronic structures are calculated by using the Korringa-Kohn-Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that we can increase the magnetic moment of Fe in p-type GaN by oxygen co-doping. Mechanism of exchange interactions between magnetic ions in p-type (Ga,Fe)N is also studied. The effect of external magnetic field on the electronic structure of (Ga, Fe)N and p-type (Ga, Fe)N is investigated.

Energy Technology Data Exchange (ETDEWEB)

Effect of Al and AlP particles on the microstructure of near eutectic Mn-Si alloy (Mn-30 wt.%Si) was studied by Electron Probe Micro-analyzer (EPMA) and Differential Scanning Calorimeter (DSC). Crystal lattice correspondence analyses show that both Al and AlP have good lattice matching coherence relationships with MnSi phase, and the addition of Al and AlP particles results in an abnormal eutectic structure, i.e. the eutectic constitution MnSi and Mn{sub 5}Si{sub 3} precipitate separately: MnSi precipitates firstly, and then the Mn{sub 5}Si{sub 3} phase.

CERN Document Server

We investigate decoherence in quantum systems coupled via dephasing-type interactions to an arbitrary environment with chaotic underlying classical dynamics. The coherences of the reduced state of the central system written in the preferential energy eigenbasis are quantum Loschmidt echoes, which in the strong coupling regime are characterized at long times scales by fluctuations around a constant mean value. We show that due to the chaotic dynamics of the environment, the mean value and the width of the Loschmidt echo fluctuations are inversely proportional to the quantity we define as the effective Hilbert space dimension of the environment, which in general is smaller than the dimension of the entire available Hilbert space. Nevertheless, in the semiclassical regime this effective Hilbert space dimension is in general large, in which case even a chaotic environment with few degrees of freedom produces decoherence without revivals. Moreover we show that in this ...

Energy Technology Data Exchange (ETDEWEB)

Gamma-aminobutyric acid type A receptor-associated protein (GABARAP) belongs to a family of small ubiquitin-like adaptor proteins implicated in intracellular vesicle trafficking and autophagy. We have used diffusion-ordered nuclear magnetic resonance spectroscopy to study the temperature and concentration dependence of the diffusion properties of GABARAP. Our data suggest the presence of distinct conformational states and provide support for self-association of GABARAP molecules. Assuming a monomer-dimer equilibrium, a temperature-dependent dissociation constant could be derived. Based on a temperature series of {sup 1}H{sup 15}N heteronuclear single quantum coherence nuclear magnetic resonance spectra, we propose residues potentially involved in GABARAP self-interaction. The possible biological significance of these observations is discussed with respect to alternative scenarios of oligomerization.

International Nuclear Information System (INIS)

Stimulated bremsstrahlung in an undulating electric field in the lasing beam direction (electric wiggler) was shown to be possible from the quantum- mechanical viewpoint. Herein, this possibility is scrutinized from the viewpoint of classical electrodynamics. It is found that if stimulated bremsstrahlung in a transverse undulating magnetic field (magnetic wiggler) occurs, stimulated bremsstrahlung in the electric wiggler must also occur. We further show that a free electron laser (FEL) using a magnetic wiggler to provide a catalyzer field for stimulated bremsstrahlung cannot serve as a practical FEL operating in the soft x-ray region from both theoretical and experimental viewpoints. On the other hand, the authors demonstrate that the FEL using a traveling wake field in a two-beam elliptical pill-box cavity is well suited as a source of coherent radiation in the soft x-ray region.

International Nuclear Information System (INIS)

We present accurate tight-binding parametrizations of the first-principles augmented-plane-wave or linear-augmented-plane-wave band structures of LaCuO_3, La_2CuO_4, Ba_2CuO_4, and the high-temperature superconductor YBa_2Cu_3O_7. We discuss the methodology and efficient application of these fits, including as an example our tight-binding coherent-potential-approximation (CPA) calculations of the effects of disorder on the electronic structure of La/sub 2-//sub x/Ba/sub x/CuO/sub 4-//sub y/. Our CPA calculations support the hypothesis of a rigid-band lowering of the Fermi level for La/sub 2-//sub x/Ba/sub x/CuO_4, enhancing the density of states there. However, for La_2BaCuO/sub 4-//sub y/ they yield the interesting result that oxygen vacancies also lower E/sub F/ and raise N(E/sub F/). This is a significant result for the theory of superconductivity in these materials. In addition to CPA calculations, our parametrizations of the band structures should prove to be ...

Energy Technology Data Exchange (ETDEWEB)

In this work tests of quality control in beams of X rays have been carried out, at diagnostic level, of two radiological services equipments of Brazilian hospitals (Aracaju, SE). We obtained the air kerma and kerma rate values, the beams efficiency, the coherence between the luminous fields and the referring fields of irradiation and half-value layer to each equipment and set of parameters. The measures of direct form have been obtained using two ionization chambers, one cylindrical and another one with parallel plates. An optional method for accomplishment some of the tests were carried out with CaSO{sub 4}:Dy + Teflon thermoluminescent dosimeters. The values of air kerma were evaluated for three tube voltage, 40, 60 and 81 kV at 1.0 m from the focus of the equipments. For each one of the voltages three distinct current values were chosen besides a fixed value of exposition time. The results showed that the values of air kerma varied between 8.0 {mu}Gy and 0.35 ...

Science.gov (United States)

We attempt to image the rupture propagation of the 2004 M6.0 Parkfield earthquake by analyzing records from the USGS Parkfield seismic array (UPSAR) and other strong-motion stations. The UPSAR array consists of 12 stations distributed over about one square kilometer at a distance of 10~km from the San Andreas fault near Parkfield, California. We employ a method that uses reverse time migration to stack the seismograms at back-projected locations along the fault. We use waveform cross-correlation to align the initial P-wave arrivals and correct for small static time shifts in the records. This forces a coherent image at the hypocenter at the quake origin time. Initial results at later time steps show some evidence of the expected rupture propagation to the north. However, the resolution of the back-projection is limited by the small aperture of the UPSAR array. Records from other strong-motion stations can improve the theoretical resolution kernels but are less ...

Energy Technology Data Exchange (ETDEWEB)

The FEL electron linac consists of three buncher cavities: two accelerator cavities and a deflection cavity, each with its own phase-coherent rf source. All sources will be pulsed for 100 ..mu..s at a 1-pps rate. The phase and amplitude stability requirements are +-1/2/sup 0/, and +-1/2%. There are two subharmonic bunchers, each requiring 5 kW at 108.33 MHz. All remaining cavities operate at 1300 MHz. The fundamental buncher requires 5 kW, whereas each of the accelerating cavities requires at least 3 MW. The deflection cavity requires up to 100 kW, which is coupled from one of the accelerator cavity rf sources. Prominent features of the rf system are the phase and amplitude control circuits and the multimegawatt klystron amplifiers. Three L3707 klystrons were obtained from the AMRAD radar site at White Sands, which was decommissioned in the early 1970s. The tubes originally were designed to produce 10-MW, 10-..mu..s pulses. Each tube has delivered over 3.6-MW, ...

Energy Technology Data Exchange (ETDEWEB)

X-ray scattering from lyophilized proteins or protein-rich samples is characterized by the presence of two characteristic broad peaks at scattering angles equivalent to momentum transfer values of 0.27 and 0.6 nm{sup -1}, respectively. These peaks arise from the interference of coherently scattered photons. Once the conformation of a protein is changed, these two peaks reflect such change with considerable sensitivity. The present work examines the possibility of characterizing the most common cause of hemolytic anaemia in Egypt and many Mediterranean countries; {beta}-thalassemia, from its X-ray scattering profile. This disease emerges from a genetic defect causing reduced rate in the synthesis of one of the globin chains that make up hemoglobin. As a result, structurally abnormal hemoglobin molecules are formed. In order to detect such molecular disorder, hemoglobin samples of {beta}-thalassemia patients are collected, lyophilized and measured using a ...

International Nuclear Information System (INIS)

We report on the first measurements of the z-dependent evolution of electron-beam microbunching as revealed through coherent transition radiation (CTR) measurements in a visible self-amplified spontaneous emission free-electron laser experiment. The increase in microbunching was detected by tracking the growth of the visible CTR signals as generated from insertable metal mirrors/foils after each of the last three undulators. The same optical imaging diagnostics that were used to track the z-dependent intensity of the undulator radiation (UR) were also used to track the electron beam/CTR information. Angular distribution, beam size, and intensity data were obtained after each of the last three undulators in the five-undulator series, and spectral information was obtained after the last undulator. The exponential growth rate of the CTR was found to be very similar to that of the UR and consistent with simulations using the code GENESIS.

International Nuclear Information System (INIS)

A number of systems which can elucidate physics beyond the standard model are investigated. The production of axions by a network of cosmic strings in the early universe is calculated. This allows an upper bound to be placed on the axion decay constant, and provides the preferred Peccei-Quinn symmetry breaking scale for axions to make up the dark matter of the universe. Models of neutrino mass arising from strong interactions are investigated. These models possess a massless up quark, thereby solving the strong CP problem. A systematic analysis of the contributions to time reversal violating atomic and molecular electric dipole moments is presented. Specific contributions from the supersymmetric standard model are calculated. The contributions arising from the QCD vacuum angle are also discussed. Prospects for detecting the axion by its long range coherent force are related to measurable electron dipole moments. A method for measuring neutrino mass by nuclear ...

International Nuclear Information System (INIS)

Basic studies of the oxidation resistance of Fe-Cr binary and Fe-Cr-Ni ternary alloys in pure oxygen have shown that the excellent corrosion resistance of Alloy 800 is explicable in terms of the low defect concentrations and diffusion rates in the oxide forming on alloys of this composition in sufficiently oxidising environments. The performance of Alloy 800 in environments of particular importance to nuclear power generation is briefly reviewed to determine to what extent ideas derived from the basic studies of Fe-Cr-Ni ternary alloys are borne out in practice. The good corrosion resistance of Alloy 800 in steam and CO_2 and, to some extent, in molten salt environments is in agreement with the behaviour of ternary alloys in oxygen. Minor aliovalent alloying additions are only expected to have a significant effect on the oxidation resistance of Alloy 800 if they favour the formation of breakthrough duplex oxidation. In impure helium and liquid sodium dense coherent ...

International Nuclear Information System (INIS)

The FEL rf system was designed for 3.6-MW rf pulses from two klystrons to drive two linacs and one deflection cavity at 1300 MHz. Two 108.33-MHz subharmonic buncher cavities and one fundamental buncher were also built, each powered by a 5-kW amplifier. A single phase-coherent source drives the various amplifiers as well as the grid of the electron gun, which is pulsed at 21.67 MHz. The initial buncher system did not work as well as expected, and the first linac tank required more rf power than anticipated. The light output was extremely sensitive to amplitude and phase errors. More powerful klystrons were developed and installed, and a method was discovered for operating a single subharmonic buncher and allowing the first linac to complete the bunching process. This paper shows the actual configuration used to operate the laser and discusses future improvements.

Energy Technology Data Exchange (ETDEWEB)

Pumped storage plants participate in two structurally different markets: the market for scheduled energy (also known as spot market) and the reserve market. In order to achieve the best possible plant scheduling in terms of revenues the marketing of the available capacity from pumped storage plants needs to be optimised in both markets. Moreover, due to the abilities for providing reserve, pumped storage capacities within an existing power plant portfolio can lead to synergies for the whole portfolio. The optimised combined participation of a power plant in both spot and reserve market as well as the coherent portfolio effect are considered as particular challenges in energy economic assessments, e.g. in the light of investment decisions. Based on an extension project and in cooperation with RWTH Aachen University an optimised combined participation of a power plant in both markets was simulated for the first time, thereby applying an integrated optimisation ...

Energy Technology Data Exchange (ETDEWEB)

Multilayer mirrors for the extreme ultraviolet (EUV) are keyelements for numerous applications of coherent EUV sources such as newtabletop lasers and free-electron lasers. However the field ofapplications is limited by the radiation and thermal stability of themultilayers. Taking into account the growing power of EUV sources thestability of the optics becomes crucial. To overcome this problem it isnecessary to study the degradation of multilayers and try to increasetheir temporal and thermal stability. In this paper we report the resultsof detailed study of structural changes in Sc/Simultilayers when exposedto intense EUV laser pulses. Various types of surface damage such asmelting, boiling, shockwave creation and ablation were observed asirradiation fluencies increase. Cross-sectional TEM study revealed thatthe layer structure was completely destroyed in the upper part ofmultilayer, but still survived below. The layers adjacent tothe substrateremained intact even ...

Science.gov (United States)

The millimeter microwave source of gyrotron-traveling-wave amplifier (gyro-TWT) is capable of generating high power coherent radiation in a broad bandwidth, while its performance is severely deteriorated by the stability problems. This paper focuses on modeling and the stability analysis of the Naval Research Laboratory (NRL) Ka-band TE{sub 01} mode gyro-TWT based on an interaction circuit alternately loaded with lossy ceramic shells and metal rings. The propagation characteristics of the interaction circuit is analyzed first, based on which the boundary impedance method is employed to build an equivalent uniform lossy circuit. Then the stability of the interaction system is studied using linear and nonlinear theories. The analysis reveals that, due to the special waveguide structure and the dielectric loss, the propagation characteristics of the complex waveguide are similar to that of a uniform lossy circuit. The analysis of the absolute instabilities ...

International Nuclear Information System (INIS)

Recent experimental and theoretical studies of two-dimensional (2D) turbulence reveal that spectrally condensed turbulence which is a system of coupled large-scale coherent flow and broadband turbulence, is similar to plasma turbulence near the L-H transition threshold. Large condensate vortices fed via the turbulent inverse energy cascade, can control both the level of the broadband turbulence by shear decorrelation, and the energy injected into turbulence at the forcing scale via sweeping of the forcing-scale vortices. The interaction between these ingredients of spectrally condensed fluid turbulence is in many aspects similar to the interactions in the zonal flow-GAMs-turbulence system in plasma. In this paper we overview recent results on condensed 2D turbulence and present evidence of interaction between its three components: condensate structures, turbulence and forcing-scale vortices. This is compared with the modifications in the spectra of plasma ...

International Nuclear Information System (INIS)

The oscillation experiment of free-electron laser (FEL) was carried at the wave length 488 nm. The space and time properties and power of FEL were investigated. The typical macropulse structure indicated the time interval 20 ms and the pulse width 2 to 3 ms. About 1 ns was necessary to build up FEL. The space distribution of FEL showed beautiful TEM_0_0 mode, TEM_0_1 and TEM_0_2 mode. On the basis of data, 39 #mu#W average power was calculated at 2.9 mA accumulated current per bunch by integrating each response of pixel of CCD camera. The peak power was 1.2 W. In the oscillator, FEL power was average 1.2 W, peak 38 kW. On the electron beam, the stability of head tail was controlled by 6-pole-Quadrupole-6-pole (SQS) system made by an experimental basis. We succeeded the single set test, setting up single set in the ring. The characteristic properties of electron beam evaporation mirror of photo oscillator were studied and then new type photo oscillator to obtain large peak power was ...

Energy Technology Data Exchange (ETDEWEB)

The canonical quantum theory of gravity-quantum geometrodynamics (QG)-is applied to the homogeneous Bianchi type IX cosmological model. As a result, a framework for the quantum theory of homogeneous cosmologies is developed. We show that the theory is internally consistent and prove that it possesses the correct classical limit (the theory of general relativity). To emphasize the special role that the constraints play in this new theory, we compare it to the traditional ADM square-root and Wheeler-DeWitt quantization schemes. We show that, unlike traditional approaches, QG leads to a well-defined Schroedinger equation for the wavefunction of the universe that is inherently coupled to the expectation value of the constraint equations. This coupling to the constraints is responsible for the appearance of a coherent spacetime picture. Thus, the physical meaning of the constraints of the theory is quite different from Dirac's interpretation. In light of this ...

CERN Document Server

We study an exactly solvable model where an uniformly accelerated detector is linearly coupled to a massless scalar field initially in the Minkowski vacuum. Using the exact correlation functions we show that as soon as the coupling is switched on one can see information flowing from the detector to the field and propagating with the radiation into null infinity. By expressing the reduced density matrix of the detector in terms of the two-point functions, we calculate the purity function in the detector and study the evolution of quantum entanglement between the detector and the field. Only in the ultraweak coupling regime could some degree of recoherence in the detector appear at late times, but never in full restoration, as an earlier work seems to suggest. We explicitly show that under the most general conditions the detector never recovers its quantum coherence and the entanglement between the detector and the field remains large at late times. To the extent ...

Energy Technology Data Exchange (ETDEWEB)

The {sup 252}Cf-source-driven noise analysis method is a versatile measurements tool that has been applied to measurements for initial loading of reactors, quality assurance of reactor fuel elements, fuel processing facilities, fuel reprocessing facilities, fuel storage facilities, zero-power testing of reactors, verification of calculational methods, process monitoring, characterization of storage vaults, and nuclear weapons identification. This method`s broad range of application is due to the wide variety of time- and frequency domain signatures, each with unique properties, obtained from the measurement. The following parameters are obtained from this measurement: average detector count rates, detector multiplicities, detector autocorrelations, cross-correlation between detectors, detector autopower spectral densities, cross-power spectral densities between detectors, coherences, and ratios of spectral densities. All of these measured parameters can also be ...

Energy Technology Data Exchange (ETDEWEB)

Examination of a chloroform extract of Dracaena loureiri Gagnep (Agavaceae), a Thia medicinal plant possessing antibacterial activity, has led to the isolation of fifteen flavenoids. The biogenic relationships among these flavenoids isolated were briefly discussed. Definition of the skeleton and the unambiguous assignment of all of the protons of the isolates was achieved through extensive 2D-homonuclear chemical shift correlation, nuclear Overhauser effect (NOE) difference spectroscopy and 2D-NOE experiments. The {sup 1}H and {sup 13}C NMR spectra of staurosporine, a potent biologically active agent from Streptomyces staurosporeus, were unambiguously assigned by using 2D homonuclear chemical shift correlation, NOE, {sup 1}H-detected heteronuclear multiple-quantum coherence via direct coupling and via multiple-bond coupling for resonance assignments of protonated and nonprotonated carbons, respectively. S. Staurosporeus was found to utilize endogenous and exogenous ...

Energy Technology Data Exchange (ETDEWEB)

In order to predict the effect of a fuel-coolant interaction after a hypothetical core-melt-down accident, a phenomenological model has been developed to describe the thermal and hydrodynamic behavior of a high-temperature molten jet when it interacts with saturated or subcooled water in a film boiling regime. The mechanisms of jet-material erosion were analyzed by Kelvin-Helmholtz instabilities on the coherent column and by boundary layer stripping on the leading edge. The heat transfer coefficient, vapor-film thickness, and net steam generation, all of which strongly affect the jet-breakup behavior, were solved analytically. It was found that the jet breakup (or erosion) depends strongly on the steam generation from the jet/water interaction. The jet-breakup length (i.e., penetration distance) was found to be sensitive to the initial jet temperature, water subcooling, and the physical state of the ambient water. The jet-breakup length and leading-edge velocity of ...

British Library Electronic Table of Contents (United Kingdom)

The retinal degeneration 10 (rd10) mouse is a well-characterized model of autosomal recessive retinitis pigmentosa (RP), which carries a spontaneous mutation in the ? subunit of rod cGMP-phosphodiesterase (PDE?). Rd10 mouse exhibits photoreceptor dysfunction and rapid rod photoreceptor degeneration followed by cone degeneration and remodeling of the inner retina. Here, we evaluate whether gene replacement using the fast-acting tyrosine-capsid mutant AAV8 (Y733F) can provide long-term therapy in this model. AAV8 (Y733F)-smCBA-PDE? was subretinally delivered to postnatal day 14 (P14) rd10 mice in one eye only. Six months after injection, spectral domain optical coherence tomography (SD-OCT), electroretinogram (ERG), optomotor behavior tests, and immunohistochemistry showed tha...

International Nuclear Information System (INIS)

Laser frequency stabilization giving a 500-Hz Allan deviation for a 2-ms integration time with drift reduced to 7 kHz/min over several minutes was achieved at 1536 nm in the optical communication band. A continuously regenerated spectral hole in the inhomogeneously broadened "4I_1_5_/_2(1)#->#"4I_1_3_/_2(1) optical absorption of an Er"3"+:Y_2SiO_5 crystal was used as the short-term frequency reference, while a variation on the locking technique allowed simultaneous use of the inhomogeneously broadened absorption line as a long-term reference. The reported frequency stability was achieved without vibration isolation. Spectral hole burning frequency stabilization provides ideal laser sources for high-resolution spectroscopy, real-time optical signal processing, and a range of applications requiring ultra-narrow-band light sources or coherent detection; the time scale for stability and the compatibility with spectral hole burning devices make this technique ...

Energy Technology Data Exchange (ETDEWEB)

An International Workshop on Metrology for X-ray and Neutron Optics has been held March 16-17, 2000, at the Advanced Photon Source, Argonne National Laboratory, near Chicago, Illinois (USA). The workshop gathered engineers and scientists from both the U.S. and around the world to evaluate metrology instrumentation and methods used to characterize surface figure and finish for long grazing incidence optics used in beamlines at synchrotrons radiation sources. This two-day workshop was motivated by the rapid evolution in the performance of x-ray and neutron sources along with requirements in optics figure and finish. More specifically, the performance of future light sources, such as free-electron laser (FEL)-based x-ray sources, is being pushed to new limits in term of both brilliance and coherence. As a consequence, tolerances on surface figure and finish of the next generation of optics are expected to become tighter. The timing of the workshop provided an ...

International Nuclear Information System (INIS)

The present article outlines major features of the free electron laser (FEL) and reviews research and development of FEL. Relations among the oscillation frequency, electron beam parameters and wiggler parameters, the physical mechanism of amplification and the physical process of saturation are discussed to identify the difference between FEL and other lasers. The report also outlines techniques for accelerators which are used to generate high-quality, high-energy electron beams required for FEL experiments. Techniques to achieve a short wavelength, high output and high efficiency, and applications of FEL are also discussed. FEL consists of an electron accelerator, wiggler and optical resonator. In FEL, electron beams with a relativistic energy interact resonantly with an electromagnetic field to generate coherent electromagnetic waves. Unlike conventional lasers, FEL does not surfer from restrictions on its oscillation frequency associated with atomic, molecular ...

International Nuclear Information System (INIS)

Computer simulated small-angle neutron scattering curves of spherical poly disperse extruded unilamellar liposomes from saturated 1,2-diacylphosphatidylcholines in the aqueous phase are evaluated by using a multi shell model, which divides the lipid bilayer of liposomes into the polar head group region, and the nonpolar hydrocarbon region consisting of the chains of methylene groups and of the region of methyl groups. In the each of these regions, the coherent neutron scattering length density is supposed to by homogeneous. The evaluation is based on obtaining of radius of gyration from Kratky-Porod plot of small-angle neutron scattering data in the Guinier region of small scattering vector values. From radii of gyration obtained at several different molar fractions N_D_2_O/(N_D-2_O + N_H_2_O) in the aqueous phase (contrasts) and independent volumetric data, the lipid surface area A_L (or the bilayer thickness d_L) and the number of water molecules N_L penetrated ...

Energy Technology Data Exchange (ETDEWEB)

In the upgrade project of the Beijing Electron-Positron Collider (BEPCII), a novel Detector-Control System (DCS) for the Beijing Spectrometer (BESIII) has been built and started its successful operation for the BESIII Commissioning. The main task of the DCS is to monitor and control the status of the BESIII detector and to guarantee a safe operation of the detector. The DCS must provide a uniform and coherent interface to detector operators even though there are a large number of distributed I/O channels from a large variety of equipments. For this reason, the DCS is hierarchically organized and divided into three layers: front-end layer (FEL), local control layer (LCL) and global control layer (GCL). In the FEL, devices ranging from simple sensors up to complex computer-based devices like embedded systems and programmable logical controllers (PLC) are utilized. A LabVIEW-based software framework has been developed for the LCL. Network communication and web server ...

CERN Document Server

We consider network coding for networks experiencing worst-case bit-flip errors, and argue that this is a reasonable model for highly dynamic wireless network transmissions. We demonstrate that in this setup prior network error-correcting schemes can be arbitrarily far from achieving the optimal network throughput. We propose a new metric for errors under this model. Using this metric, we prove a new Hamming-type upper bound on the network capacity. We also show a commensurate lower bound based on GV-type codes that can be used for error-correction. The codes used to attain the lower bound are non-coherent (do not require prior knowledge of network topology). The end-to-end nature of our design enables our codes to be overlaid on classical distributed random linear network codes. Further, we free internal nodes from having to implement potentially computationally intensive link-by-link error-correction.

Energy Technology Data Exchange (ETDEWEB)

We review the recent development of bendable x-ray optics used for focusing of beams of soft and hard x-rays at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory and at the Linac Coherent Light Source (LCLS) x-ray free electron laser (FEL) at the Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory. For simultaneous focusing in the tangential and sagittal directions, two elliptically cylindrical reflecting elements, a Kirkpatrick-Baez (KB) pair, are used. Because fabrication of elliptical surfaces is complicated, the cost of directly fabricated tangential elliptical cylinders is often prohibitive. Moreover, such optics cannot be easily readjusted for use in multiple, different experimental arrangements, e.g. at different focal distances. This is in contrast to flat optics that are simpler to manufacture and easier to measure by conventional interferometry. The tangential figure of a flat substrate is changed by placing ...

Energy Technology Data Exchange (ETDEWEB)

Three popular imaging methods were used to carry out seismic migration from the Alberta foothills: Kirchhoff integral, reverse-time and explicit finite-difference migration methods. The imaging comparisons of reverse-time, Kirchhoff and f-x post-stack depth migration leads to the following conclusions. All of the three migration methods can provide acceptable and well-imaged intermediate results on the simplest model. Post-stack migration was not very sensitive to the accuracy of the velocity field once a reliable structural stack was available. With respect to the imaging accuracy and calculation cost, the Kirchhoff migration method seemed to be superior to reverse-time and f-x migration algorithms because its results on different kinds of velocity cases were basically kept coherent and consistent with the velocity model given by Mobil. Because of the lack of an accurate velocity field, reverse-time migration was less stable than the other two imaging methods, ...

Energy Technology Data Exchange (ETDEWEB)

Since information has been regarded os a physical entity, the field of quantum information theory has blossomed. This brings novel applications, such as quantum computation. This field has attracted the attention of numerous researchers with backgrounds ranging from computer science, mathematics and engineering, to the physical sciences. Thus, we now have an interdisciplinary field where great efforts are being made in order to build devices that should allow for the processing of information at a quantum level, and also in the understanding of the complex structure of some physical processes at a more basic level. This thesis is devoted to the theoretical study of structures at the nanometer-scale, 'nanostructures', through physical processes that mainly involve the solid-state and quantum optics, in order to propose reliable schemes for the processing of quantum information. Initially, the main results of quantum information theory and quantum computation are ...

Science.gov (United States)

Two branches of research are conducted in this thesis. The first deals with nonlinear combustion response as a mechanism for triggering combustion instabilities in solid rocket motors. A nonlinear wave equation is developed to study a wide class of combustion response functions to second-order in fluctuation amplitude. Conditions for triggering are derived from analysis of limit cycles, and regions of triggering are found in parametric space. Introduction of linear cross-coupling and quadratic self-coupling among the acoustic modes appears to be how the nonlinear combustion response produces triggering to a stable limit cycle. Regions of initial conditions corresponding to stable pulses were found, suggesting that stability depends on initial phase angle and harmonic content, as well as the composite amplitude, of the pulse. Also, dependence of nonlinear stability upon system parameters is considered. The second part of this thesis presents research for a controller to improve the ...

Energy Technology Data Exchange (ETDEWEB)

The work reported here concerns the evolution of the shape of a coherent, cubic precipitate as it grows by coarsening. The work was motivated by the need to explain recent experimental observations that show that cuboidal ..gamma.. Ni/sub 3/Al precipitates in Ni-Al alloys resist coarsening and decompose into doublets of parallel rectangular plates and octets of small cubes. The theoretical model assumes a precipitate of cubic phase with negative elastic anisotropy, and neglects any difference between the elastic constants of the precipitate and the matrix. The elastic energy of the precipitate is then calculated as a function of its morphology, including the possibility of decomposition into doublets or octets of discrete particles. The results show that a cuboidal precipitate with (100) faces and edge length, 2a, is metastable with respect to transition to a doublet of discrete plates, with dimensions a x 2a x 2a, that are separated by the distance ..mu.. - a, ...

International Nuclear Information System (INIS)

The simplest high gain free electron laser (FEL) amplifier concept is proposed. A klystron amplifier has the useful property that the various electronic processes take place in separate portions of the amplifier, rather than overlapping as in FEL amplifier with an uniform undulator. The klystron consists of two fundamental parts: succession of 2-3 cascades (modulator), and an output undulator (radiator) in which the modulated electron beam coherently radiates. Each cascade consists of uniform undulator and dispersion section. Unlike distributed optical klystrons, we have a high gain per cascade pass. This has a few consequences. First, klystron gain does not depend on the bunch compression in the injector linac, i.e. maximum gain per cascade pass at high peak beam current is the same at low peak beam current, without compression. Conventional, short-wavelength FEL amplifier and distributed optical klystron require electron beam peak current of a few kA. Second, ...

Energy Technology Data Exchange (ETDEWEB)

In the two decades since the presentation of the first experimental results, the study of high-power microwaves (HPM) has aimed at the production of microwave pulses with ever higher peak power and ever larger energy content. Drawing on the electrical pulsed power and relativistic electron beam technologies, a mix of sources have produced power levels in excess of 1 GW and pulse energies of tens to a thousand joules in both the centimeter and millimeter wavelength ranges. The potential for military applications of such powerful bursts became a major driving force for substantial research programs -- and considerable advancements -- in the United States and the former Soviet Union. The end of the Cold War and a reexamination of national priorities has diminished the momentum of military HPM development in these countries. Nevertheless, the field hasn`t reached its limits, in capability or applicability, and one sees at present a diffusion of the technology across national borders. As ...

Energy Technology Data Exchange (ETDEWEB)

Individual nanoscale building blocks exhibit a wide range of size-dependent properties, since their size can be tuned over known characteristic length scales of bulk materials. In the last several years, the possibility of combining different materials in the form of two and three component nanoparticles (NPs) has been extensively explored. Also multi-component materials can be obtained via self-assembly of NPs from their binary colloidal mixtures. These new nanocrystal solids may possess tunable collective properties that originate from interactions between size and composition controlled building blocks. Exchange coupling between neighboring NPs of magnetically soft and hard materials enhances the magnetic energy product of the nanocomposite material. Randomly mixed solids of small and large semiconducting CdSe NPs revealed enhancement of photoluminescence intensity of large semiconductor particles accompanied by quenching of photoluminescence of the small particles because of ...

International Nuclear Information System (INIS)

This topical review provides an overview of quantum dot micropillars and their application in cavity quantum electrodynamics (cQED) experiments. The development of quantum dot micropillars is motivated by the study of fundamental cQED effects in solid state and their exploitation in novel light sources. In general, light-matter interaction occurs when the dipole of an emitter couples to the ambient light field. The corresponding coupling strength is strongly enhanced in the framework of cQED when the emitter is located inside a low mode volume microcavity providing three-dimensional photon confinement on a length scale of the photon wavelength. In addition, coherent coupling between light and matter, which is essential for applications in quantum information processing, can be achieved when dissipative losses, predominantly due to photon leakage out of the cavity, are strongly reduced. In this paper, we will demonstrate that high-quality, low mode volume quantum ...

Science.gov (United States)

Decadal-scale climate variations over the Pacific Ocean and its surroundings are strongly related to the so-called Pacific decadal oscillation (PDO) which is coherent with wintertime climate over North America and Asian monsoon, and have important impacts on marine ecosystems and fisheries. In a near-term climate prediction covering the period up to 2030, we require knowledge of the future state of internal variations in the climate system such as the PDO as well as the global warming signal. We perform sets of ensemble hindcast and forecast experiments using a coupled atmosphere-ocean climate model to examine the predictability of internal variations on decadal timescales, in addition to the response to external forcing due to changes in concentrations of greenhouse gases and aerosols, volcanic activity, and solar cycle variations. Our results highlight that an initialization of the upper-ocean state using historical observations is effective for successful ...

Energy Technology Data Exchange (ETDEWEB)

Measurements of temperature and NO concentration in laminar, partially premixed methane-air flames stabilized on a ceramic burner in coflow are reported. The NO concentration and temperature were determined by laser-induced fluorescence (LIF) and coherent anti-Stokes Raman scattering (CARS), respectively. Upstream heat loss to the burner was varied by changing the exit velocity of the fuel-air mixture at a constant equivalence ratio of 1,3; this alters the structure of the flame from an axisymmetric Bunsen-type to a strongly stabilized flat flame. To facilitate analysis of the results, a method is derived for separating the effects of dilution from those of chemical reaction based on the relation between the measured temperature and the local mixture fraction, including the effects of upstream heat loss. Using this method, the amount of NO formed during burnout of the hot, fuel-rich combustion products can be ascertained. In the Bunsen-type flame, it is seen that ...

Energy Technology Data Exchange (ETDEWEB)

In order to make it easy for the reader to see the specific research carried out and the progress made, the following report of progress is done by topic. Each item has a format layout of Topic, Investigators, Objective, Significance, and Description of Progress, followed at the end by the relevant references. As is clear from the topics listed, the emphasis of the GW nuclear theory group has been on the structure and electromagnetic interactions of few-body nuclei. Both low- and intermediate-energy electromagnetic disintegration of these nuclei is considered, including coherent photoproduction of {pi} mesons. When the excitation energy of the target nucleus is low, the aim has been to handle the continuum part of the theoretical work numerically with no approximations, that is, by means of full three- or four-body dynamics. When structure questions are the issue, numerically accurate calculations are always carried through, limited only by the underlying two-body ...

International Nuclear Information System (INIS)

I present an exact calculation of free-electron-laser (FEL) eigenmodes (fundamental as well as higher order modes) in the exponential-gain regime. These eigenmodes specify transverse profiles and exponential growth rates of the laser field, and they are self-consistent solutions of the coupled Maxwell-Vlasov equations describing the FEL interaction taking into account the effects due to energy spread, emittance and betatron oscillations of the electron beam, and diffraction and guiding of the laser field. The unperturbed electron distribution is assumed to be of Gaussian shape in four dimensional transverse phase space and in the energy variable, but uniform in longitudinal coordinate. The focusing of the electron beam is assumed to be matched to the natural wiggler focusing in both transverse planes. With these assumptions the eigenvalue problem can be reduced to a numerically manageable integral equation and solved exactly with a kernel iteration method. An approximate, but more ...

International Nuclear Information System (INIS)

The paper discusses recent results on the development of localized arc filament plasma actuators and their use in controlling high-speed and high Reynolds number jet flows. Multiple plasma actuators (up to 8) are controlled using a custom-built 8-channel high-voltage pulsed plasma generator. The plasma generator independently controls pulse repetition rate (0-200 kHz), duty cycle and phase for each individual actuator. Current and voltage measurements demonstrated the power consumption of each actuator to be quite low (20 W at 20% duty cycle). Emission spectroscopy temperature measurements in the pulsed arc filament showed rapid temperature increase over the first 10-20 ?s of arc operation, from below 1000 deg. C to up to about 2000 deg. C. At longer discharge pulse durations, 20-100 ?s, the plasma temperature levels off at approximately 2000 deg. C. Modelling calculations using an unsteady, quasi-one-dimensional arc filament model showed that rapid localized heating in the arc ...

Energy Technology Data Exchange (ETDEWEB)

Decay processes of H{sub 2}{sup -} anions in {gamma}-rays-irradiated solid parahydrogen were studied by using ESR spectrometer. The following interesting results were obtained. First, the initial amount of ortho-H{sub 2}{sup -} anions in the {gamma}-irradiated solid parahydrogen was three times as large as those of para-H{sub 2}{sup -} anions. Second, the amount of para-H{sub 2}{sup -} anions decreases faster than that of ortho-H{sub 2}{sup -} anions upon storage of the irradiated samples at 4.2 K. Third, the decay rate of H{sub 2}{sup -} anions is accelerated by the addition of D{sub 2} molecules. Forth, H{sub 2}{sup -} anions at 2.2 K decay faster than at 4.2 K. According to the parity conservation rule in a homonuclear diatomic molecule, the energy of ortho-H{sub 2}{sup -} anions at the ground state is lower than that of para-H{sub 2}{sup -} anions, whereas that of ortho-H{sub 2} molecules is higher than that of para-H{sub 2} molecules at low temperatures. The first and second ...

Energy Technology Data Exchange (ETDEWEB)

The traditional process for developing large-scale simulations is cumbersome, time consuming, costly, and in some cases, inadequate. The topics of software components and component-based software engineering are being explored by software professionals in academic and industrial settings. A component is a well-delineated, relatively independent, and replaceable part of a software system that performs a specific function. Many researchers have addressed the potential to derive a component-based approach to simulations in general, and a few have focused on military simulations in particular. In a component-based approach, functional or logical blocks of the simulation entities are represented as coherent collections of components satisfying explicitly defined interface requirements. A simulation is a top-level aggregate comprised of a collection of components that interact with each other in the context of a simulated environment. A component may represent a ...

Energy Technology Data Exchange (ETDEWEB)

This paper presents a real-time wavelet-Fuzzy combined approach for digital relaying. The algorithm for fault classification employs wavelet multi resolution analysis (MRA) to overcome the difficulties associated with conventional voltage and current based measurements due to effect of factors such as fault inception angle, fault impedance and fault distance. The proposed algorithm for fault location, different from conventional algorithms that are based on deterministic computations on a well-defined model to be protected, employs wavelet transform together with fuzzy logic. The wavelet transform captures the dynamic characteristics of the non-stationary transient fault signals using wavelet MRA coefficients. The fuzzy logic is employed to incorporate expert evaluation through fuzzy inference system (FIS) so as to extract important features from wavelet MRA coefficients for obtaining coherent conclusions regarding fault location. Computer simulations using MATLAB ...

Energy Technology Data Exchange (ETDEWEB)

The in-plane resistivity, in-plane absolute thermopower, and upper critical field measurements are reported for single-crystal samples of YNi{sub 2}B{sub 2}C and LuNi{sub 2}B{sub 2}C superconductors. The in-plane resistivity shows metallic behavior and varies approximately linearly with temperature near room temperature (RT) but shows nearly quadratic behavior in temperature at low temperatures. The YNi{sub 2}B{sub 2}C and LuNi{sub 2}B{sub 2}C single-crystal samples exhibit large transverse magnetoresistance ({approx}6{endash}8{percent} at 45 kOe) in the ab plane. The absolute thermopower S(T) is negative from RT to the superconducting transition temperature T{sub c}. Its magnitude at RT is a few times of the value for a typical good metal. S(T) is approximately linear in temperature between {approx}150 K and RT. Extrapolation to T=0 gives large intercepts (few {mu}V/K) for both samples suggesting the presence of a much larger {open_quotes}knee{close_quotes} than would be expected from ...

Science.gov (United States)

Available from UMI in association with The British Library. Requires signed TDF. Design of time and correlation windows for non -parametric frequency response estimates. The thesis deals with problems that arise in the field of spectral analysis due to finite observations of input and output records. In particular, it is concerned with the method of applying time and correlation windows in spectral analysis procedures to obtain non-parametric frequency response estimates of open-loop time invariant systems. The thesis reviews and develops the sources of error that arise when frequency response techniques are applied directly to windowed records of input and output data to estimate the frequency response of open loop systems. Having identified the cause of these errors, methods of eliminating or reducing them are studied. The techniques introduced involve the use of differing time windows for the input and output data records. It is shown that windows can be designed on the basis of ...

Science.gov (United States)

The critical currents of A-15 phase Nb(,3)Sn, V(,3)Si, Nb(,3)Ge, V(,3)Ga, and Nb-Sn with a few at.% Ga and Al(,2)O(,3) have been measured at temperatures up to T(,c) and in magnetic fields up to 8T to study fundamental flux pinning interactions as a function of defect size and density. The samples are electron beam evaporated films typically 2 (mu)m thick. Their particular usefulness for this study is that they span the clean to dirty limits and their normal state resistivity and grain size can be controlled by deposition parameters. The grain boundaries are the defects most responsible for flux pinning. The electron scattering mechanism is based on the local change in the coherence length due to increased conduction electron scattering and is chosen from among several possible mechanisms to calculate the elementary pinning force at a grain boundary. A direct summation of the elementary pinning force of each boundary is compared with the experimental results. ...

International Nuclear Information System (INIS)

This document - IAEA Safeguards: Implementation Blueprint of Commercial Satellite Imagery - constitutes the second report from SSC Satellitbild giving a structured view and solid guidelines on how to proceed with a conceivable implementation of satellite imagery to support Safeguards activities of the Agency. This Phase 2 report presents a large number of concrete recommendations regarding suggested management issues, work organisation, imagery purchasing and team building. The study has also resulted in several lists of actions and preliminary project plans with GANT schedules concerning training, hardware and software, as well as for the initial pilot studies. In both the Phase 1 and Phase 2 studies it is confirmed that the proposed concept of a relatively small Imagery Unit using high-resolution data will be a sound and feasible undertaking. Such a unit capable of performing advanced image processing as a tool for various safeguard tasks will give the Agency an effective instrument ...